Specification
Title of invention: secondary battery and insulating plate for secondary battery
Technical field
[One]
Mutual citation with related applications
[2]
This application claims the interests of priority based on Korean Patent Application No. 10-2018-0010900 filed on January 29, 2018 and Korean Patent Application No. 10-2018-0125529 filed on October 19, 2018. All contents disclosed in the literature are included as part of this specification.
[3]
Technical field
[4]
The present invention relates to an insulating plate for a secondary battery and a method of manufacturing the same, and more particularly, to an insulating plate for a secondary battery and a secondary battery that improves properties such as heat resistance and chemical resistance, and suppresses dust generation during punching.
Background
[5]
In general, types of secondary batteries include nickel cadmium batteries, nickel hydride batteries, lithium ion batteries, and lithium ion polymer batteries. These secondary batteries are not only small products such as digital cameras, P-DVDs, MP3Ps, mobile phones, PDAs, portable game devices, power tools, and E-bikes, but also large-scale products requiring high output such as electric vehicles and hybrid vehicles, and surplus power generation. It is also applied and used in power storage devices for storing electric power or renewable energy and power storage devices for backup.
[6]
In order to manufacture such a secondary battery, first, an electrode active material slurry is coated on a positive electrode current collector and a negative electrode current collector to prepare a positive electrode and a negative electrode, and then stacked on both sides of a separator to form an electrode assembly. To form. Then, the electrode assembly is accommodated in the battery case, and the electrolyte is injected and then sealed.
[7]
Secondary batteries are classified into pouch type and can type, depending on the material of the case accommodating the electrode assembly. The pouch type accommodates the electrode assembly in a pouch made of a flexible polymer material having a non-uniform shape. And, the can type accommodates the electrode assembly in a case made of a material such as metal or plastic having a uniform shape.
[8]
The can type secondary battery is classified into a prismatic type in which the case has a polygonal shape, a cylinder type in which the case has a cylindrical shape, and the like, according to the shape of the battery case.
[9]
1 is a partial cross-sectional view of a conventional cylindrical secondary battery 2.
[10]
In general, as shown in FIG. 1, the cylindrical secondary battery 2 includes a cylindrical battery can 12, a jelly-roll electrode assembly 13 accommodated in the battery can 12, and a battery can 12. The cap assembly 11 coupled to the top of the cap assembly 11, the beading portion 14 provided at the front end of the battery can 12 to mount the cap assembly 11, and the crimping portion 15 for sealing the battery can 12. Include.
[11]
The cap assembly 11 is a top cap 111 that seals the open portion of the battery can 12 and forms a positive terminal, a PTC element 112 that blocks current by increasing resistance when the temperature inside the battery increases, and an abnormal current. Due to the safety vent 113 that cuts off the current when the pressure inside the battery rises and exhausts the gas inside, the CID gasket 114 electrically separates the safety vent 113 from the CID filter 115 except for a specific part, A positive electrode lead 131 connected to the positive electrode is connected, and a CID filter 115 that blocks current when a high voltage occurs in the battery is sequentially stacked.
[12]
In addition, the cap assembly 11 is installed on the beading portion 14 of the battery can 12 while being mounted on the crimping gasket 116. Therefore, under normal operating conditions, the anode of the electrode assembly 13 is connected to the top cap 111 via the anode lead 131, the CID filter 115, the safety vent 113, and the PTC element 112 to prevent electricity. Achieve.
[13]
An insulating plate 26 is disposed at the top and bottom of the electrode assembly 13, respectively. At this time, the upper insulating plate 26 disposed at the top insulates between the electrode assembly 13 and the cap assembly 11, and the lower insulating plate (not shown) disposed at the bottom is the electrode assembly 13 and the battery can 12 Insulate between the bottoms of.
[14]
However, in the case of the conventional cylindrical secondary battery 2, the material of the insulating plate 26 is made of a thermoplastic resin such as polyethylene or polypropylene, which has an insulating property, an electrolyte resistance, and excellent punching processability. . However, the melting point of this thermoplastic resin was considerably low, ranging from 200°C to 250°C. In addition, since it is made of a thermoplastic resin, when the internal temperature of the secondary battery 2 rapidly rises and exceeds 250° C., the insulating plate 26 melts and a short circuit occurs. To solve this problem, a technique for increasing the thickness of the insulating plate 26 has also been proposed, but there is a problem in that the capacity and efficiency of the battery decrease due to the decrease in the internal space of the secondary battery 2.
[15]
Recently, a technology for manufacturing the insulating plate 26 by coating phenol, which is a thermosetting resin, has been proposed on a fabric of glass fiber. However, the melting point of phenol itself was very low at 40° C., and even if it was coated on a glass fiber fabric, there was a problem in that it was oxidized to carbon dioxide or carbon monoxide at 600° C., thereby reducing the mass. In addition, when phenol is coated on a glass fiber fabric and then punched into a round disk shape, a lot of dust is generated and continuous production is difficult, and there is a problem in that the production amount decreases and the manufacturing cost increases.
Detailed description of the invention
Technical challenge
[16]
The problem to be solved by the present invention is to provide a secondary battery and an insulating plate for a secondary battery that improves properties such as heat resistance and chemical resistance, and suppresses dust generation during punching.
[17]
The problems of the present invention are not limited to the problems mentioned above, and other problems that are not mentioned will be clearly understood by those skilled in the art from the following description.
Means of solving the task
[18]
In the insulating plate for a secondary battery according to an embodiment of the present invention for solving the above problem, in the insulating plate inserted into the case of the secondary battery, the glass fiber yarns formed by crossing each other by weft and warp; It includes a silicone rubber coated on at least one side of the glass fiber.
[19]
In addition, the silicone rubber may include a first silicone rubber attached to the glass fiber yarns; It may include a second silicone rubber inserted into the voids formed between the glass fiber yarns.
[20]
In addition, the glass fiber yarns cross each other in an orthogonal shape, and the second silicone rubber may be inserted into a void formed between the orthogonal glass fiber yarns.
[21]
In addition, the thickness may be the same as the thickness of the glass fiber.
[22]
In addition, the silicone rubber may include a first silicone rubber coated on at least one surface of the glass fiber first; It may include a second silicone rubber coated on the first silicone rubber.
[23]
In addition, the first silicone rubber may be laminated on at least one side of the glass fiber, and the second silicone rubber may be laminated on the first silicone rubber.
[24]
In addition, the silicone rubber may be laminated on at least one side of the glass fiber.
[25]
In addition, the glass fiber may be formed in a disk shape.
[26]
In addition, the silicone rubber may be coated on both sides of the glass fiber.
[27]
In addition, the glass fiber may have a composition ratio of 70 to 80 wt%, and the silicone rubber may have a composition ratio of 20 to 30 wt%.
[28]
In addition, the silicone rubber may include a silicone polymer and a flame retardant.
[29]
In addition, the silicone polymer may have a composition ratio of 10 to 20 wt%, and the flame retardant may have a composition ratio of 10 to 15 wt%.
[30]
In addition, the silicone rubber may further contain a pigment.
[31]
In addition, the pigment may have a composition ratio of 5 wt% or less.
[32]
A secondary battery according to an embodiment of the present invention for solving the above problem includes a cylindrical battery can; A jelly-roll type electrode assembly accommodated in the battery can; A cap assembly coupled to an upper portion of the battery can; A beading portion provided at the front end of the battery can to mount the cap assembly; A crimping part for sealing the battery can; And an insulating plate insulating the electrode assembly, wherein the insulating plate includes: glass fibers formed by intersecting each other by means of a weft and a warp yarn; And a silicone rubber coated on at least one side of the glass fiber.
[33]
In addition, the insulating plate may be an upper insulating plate disposed between the electrode assembly and the cap assembly.
[34]
In addition, the insulating plate may be a lower insulating plate disposed between the electrode assembly and the bottom portion of the battery can.
[35]
Other specific details of the present invention are included in the detailed description and drawings.
Effects of the Invention
[36]
According to the embodiments of the present invention, there are at least the following effects.
[37]
By coating a silicone rubber on a glass fiber fabric to prepare an insulating plate for a secondary battery, properties such as heat resistance and chemical resistance can be improved.
[38]
In addition, when manufacturing an insulating plate for a secondary battery by punching out the fabric of the insulating plate, dust generation is suppressed, enabling continuous production, increasing production, and reducing manufacturing cost.
[39]
In addition, since the fabric of the insulating plate has flexibility, by winding it up to easily form a mother-roll, an insulating plate for a secondary battery can be easily manufactured.
[40]
The effect according to the present invention is not limited by the contents illustrated above, and more various effects are included in the present specification.
Brief description of the drawing
[41]
1 is a partial cross-sectional view of a conventional cylindrical secondary battery.
[42]
2 is a flow chart showing a method of manufacturing an insulating plate according to an embodiment of the present invention.
[43]
3 is a partial cross-sectional view of a cylindrical secondary battery according to an embodiment of the present invention.
[44]
4 is a plan view of an insulating plate according to an embodiment of the present invention.
[45]
5 is a side view of an insulating plate according to an embodiment of the present invention.
[46]
6 is a flow chart showing a method of manufacturing an insulating plate according to another embodiment of the present invention.
[47]
7 is a partial cross-sectional view of a cylindrical secondary battery according to another embodiment of the present invention.
[48]
8 is a side view of an insulating plate according to another embodiment of the present invention.
[49]
9 is a partial cross-sectional view of a cylindrical secondary battery according to another embodiment of the present invention.
[50]
10 is a schematic diagram of a first silicone rubber coated on a glass fiber fabric according to another embodiment of the present invention.
[51]
11 is a schematic diagram of a second silicone rubber coated on a glass fiber fabric according to another embodiment of the present invention.
[52]
12 is a cross-sectional view taken along line A-A′ of an insulating plate according to another embodiment of the present invention in FIG. 11.
[53]
13 is a SEM photograph taken at 1500 times magnification by actually manufacturing an insulating plate according to another embodiment of the present invention.
[54]
14 is a SEM photograph taken at 1000 times magnification by actually manufacturing an insulating plate according to another embodiment of the present invention.
[55]
15 is a SEM photograph taken 200 times magnification by actually manufacturing an insulating plate according to another embodiment of the present invention.
[56]
16 is a SEM photograph taken at 40 times magnification by actually manufacturing an insulating plate according to another embodiment of the present invention.
[57]
17 is a graph showing a result of a heat resistance test for an insulating plate according to a manufacturing example of the present invention.
[58]
18 is a graph showing results of a heat resistance test for an insulating plate according to Comparative Example 2.
[59]
19 is a photograph showing the appearance of each electrolyte sample after a chemical resistance test.
[60]
20 is a graph showing results of a GC-MS experiment for each of the electrolyte samples.
[61]
21 is a photograph showing an exploded view of a secondary battery assembled with an insulating plate according to a Preparation Example of the present invention after a stability test.
[62]
22 is a photograph showing an exploded view of a secondary battery in which the insulating plate of Comparative Example 1 is assembled after a stability test.
[63]
23 is a photograph showing an exploded state of a secondary battery in which the insulating plate of Comparative Example 2 is assembled after a stability test.
Mode for carrying out the invention
[64]
Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in a variety of different forms. It is provided to completely inform the scope of the invention to those who have, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification.
[65]
Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used as meanings that can be commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in a commonly used dictionary are not interpreted ideally or excessively unless explicitly defined specifically.
[66]
The terms used in the present specification are for describing exemplary embodiments and are not intended to limit the present invention. In this specification, the singular form also includes the plural form unless specifically stated in the phrase. As used in the specification, “comprises” and/or “comprising” do not exclude the presence or addition of one or more other elements other than the mentioned elements.
[67]
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[68]
2 is a flowchart illustrating a method of manufacturing an insulating plate 16 according to an embodiment of the present invention.
[69]
The insulating plate 16 according to an embodiment of the present invention is manufactured by coating a silicone rubber 162 on a glass fiber fabric 161. Thereby, properties such as heat resistance and chemical resistance can be improved, and when the insulation plate 16 for secondary batteries is manufactured by punching out the insulation plate fabric, dust generation is suppressed, enabling continuous production, increasing production, and reducing manufacturing cost. Can be reduced. In addition, since the fabric of the insulating plate has flexibility, by winding it up to easily form a mother-roll, the insulating plate 16 for a secondary battery can be easily manufactured.
[70]
Hereinafter, detailed contents of each step shown in the flowchart of FIG. 2 will be described with reference to FIGS. 3 to 5.
[71]
3 is a partial cross-sectional view of a cylindrical secondary battery 1 according to an embodiment of the present invention.
[72]
Cylindrical secondary battery 1 according to an embodiment of the present invention, as shown in Figure 3, the battery can 12, a jelly-roll type electrode assembly 13 accommodated in the inside of the battery can 12 , For sealing the beading portion 14 and the battery can 12 provided at the front end of the battery can 12 to mount the cap assembly 11, the cap assembly 11 coupled to the top of the battery can 12 It includes a crimping portion 15. The cylindrical secondary battery 1 may be used as a power source for mobile phones, notebook computers, electric vehicles and the like stably providing a constant output.
[73]
The battery can 12 is made of a lightweight conductive metal material such as aluminum, nickel, stainless steel, or an alloy thereof, and may have an open portion having an open top and a closed bottom portion opposed thereto. An electrolyte solution is accommodated together with the electrode assembly 13 in the inner space of the battery can 12. The battery can 12 may be formed in a cylindrical shape, but may be formed in various shapes other than a cylindrical shape, such as a square.
[74]
The electrode assembly 13 includes two electrode plates such as a positive electrode plate and a negative electrode plate having a wide plate shape in a roll shape, and a separator interposed between the electrode plates to insulate the electrode plates from each other, or disposed on the left or right side of any one electrode plate. It may be a laminate structure having a. The laminated structure may be wound in the form of a jelly roll, and may be in various forms without limitation, such as a positive electrode plate and a negative electrode plate of a predetermined standard may be stacked with a separator interposed therebetween. Each of the two electrode plates has a structure in which an active material slurry is applied to a current collector in the form of a metal foil or metal mesh including aluminum and copper. The slurry may be formed by stirring a particulate active material, an auxiliary conductor, a binder, a plasticizer, and the like in a state in which a solvent is added. The solvent is removed in a subsequent process. In the direction in which the electrode plate is wound, uncoated portions to which the slurry is not applied may exist at the start and end of the current collector. A pair of leads corresponding to each electrode plate is attached to the uncoated portion. The positive electrode lead 131 attached to the upper end of the electrode assembly 13 is electrically connected to the cap assembly 11, and the negative electrode lead (not shown) attached to the lower end of the electrode assembly 13 is It is connected to the lower surface. However, the present invention is not limited thereto, and both the positive lead 131 and the negative lead may be drawn in a direction toward the cap assembly 11.
[75]
An insulating plate 16 insulating the electrode assembly 13 is disposed at the top and bottom of the electrode assembly 13, respectively. At this time, the upper insulating plate 16 disposed at the top is disposed between the electrode assembly 13 and the cap assembly 11 to insulate the electrode assembly 13, and the lower insulating plate (not shown) disposed at the bottom is an electrode assembly ( 13) and the bottom of the battery can 12 to insulate the electrode assembly 13. The insulating plate 16 according to an embodiment of the present invention may be an upper insulating plate 16 disposed above the electrode assembly, as shown in FIG. 3, but is not limited thereto, and a lower insulating plate disposed below the electrode assembly It may be (not shown). A detailed description of the insulating plate 16 according to an embodiment of the present invention will be described later.
[76]
In the center of the battery can 12, a center pin (not shown) that prevents the electrode assembly 13 wound in the form of a jelly roll from being unwound and serves as a passage for gas inside the secondary battery 1 is inserted. May be.
[77]
The electrolyte filled in the battery can 12 is to move lithium ions generated by the electrochemical reaction of the electrode plate during charging and discharging of the secondary battery 1, and is a non-aqueous mixture of lithium salts and high-purity organic solvents. It may include a polymer using a system organic electrolyte or a polymer electrolyte.
[78]
The cap assembly 11 is coupled to an opening formed at the top of the battery can 12 to seal the opening of the battery can 12. The cap assembly 11 may be formed in various shapes such as a circular shape or a square shape according to the shape of the battery can 12. According to an embodiment of the present invention, since the battery can 12 is formed in a cylindrical shape, in this case, it is preferable that the cap assembly 11 is also formed in a disk shape corresponding thereto.
[79]
According to an embodiment of the present invention, the cap assembly 11 seals the open portion of the battery can 12 and forms a positive terminal, and blocks the current when the pressure inside the battery increases due to an abnormal current. A safety vent 113 for exhausting internal gas and a positive electrode lead 131 connected to the positive electrode of the electrode assembly 13 are connected, and a current blocking member that blocks current when a high voltage occurs in the battery is sequentially stacked. I can. In addition, the cap assembly 11 is installed on the beading portion 14 of the battery can 12 while being mounted on the crimping gasket 116. Accordingly, under normal operating conditions, the positive electrode of the electrode assembly 13 is connected to the top cap 111 via the positive electrode lead 131, the current blocking member, the safety vent 113, and the PTC element 112 to form electricity.
[80]
The top cap 111 is disposed on the uppermost portion of the cap assembly 11 to protrude upwardly to form a positive terminal. Accordingly, the top cap 111 may be electrically connected to an external device such as a load or a charging device. A gas hole 1111 through which gas generated inside the secondary battery 1 is discharged may be formed in the top cap 111. Therefore, when gas is generated from the electrode assembly 13 side and the internal pressure increases due to a cause such as overcharging, the CID filter 115 and the safety vent 113 of the current blocking member rupture, and the internal gas is ruptured. It can be discharged to the outside through the portion and gas hole 1111. Accordingly, charging and discharging may no longer proceed, and safety of the secondary battery 1 may be ensured. The top cap 111 may be made of a metal material such as stainless steel or aluminum.
[81]
The thickness of the portion of the top cap 111 in contact with the safety vent 113 is not particularly limited as long as it is a range capable of protecting various components of the cap assembly 11 from external pressure, for example, It may be 0.3 to 0.5 mm. If the thickness of the top cap 111 is too thin, it is difficult to exhibit mechanical stiffness, and if it is too thick, the capacity of the battery compared to the same standard may be reduced by increasing the size and weight.
[82]
The safety vent 113 serves to block current or exhaust gas when the pressure inside the battery increases due to an abnormal current, and may be made of a metal material. The thickness of the safety vent 113 may vary depending on the material and structure, and is not particularly limited as long as it is capable of discharging gas or the like while bursting when a predetermined high pressure occurs inside the battery, and may be, for example, 0.2 to 0.6 mm.
[83]
A current interrupt device (CID) is positioned between the safety vent 113 and the electrode assembly 13 to electrically connect the electrode assembly 13 and the safety vent 113. The current blocking member is a CID gasket that spatially separates and insulates the CID filter 115 and the safety vent 113 except for a part of the CID filter 115 and a portion of the CID filter 115 that transmits current by contacting the safety vent 113 It includes (114).
[84]
Accordingly, in a normal state, the current generated from the electrode assembly 13 flows through the positive electrode lead 131 through the CID filter 115 to the safety vent 113, thereby discharging the secondary battery 1. However, when the internal pressure of the secondary battery 1 increases due to the abnormal current, and the internal pressure of the battery increases due to gas generated inside the secondary battery 1 due to the abnormal current, the safety vent 113 and the CID filter 114 ), the connection between them is detached, or the CID filter 114 is ruptured. As a result, electrical connection between the safety vent 113 and the electrode assembly 13 is cut off, thereby ensuring safety.
[85]
The cap assembly 11 may further include a positive temperature coefficient element (PTC) 112 between the safety vent 113 and the top cap 111. The PTC element 112 blocks current by increasing the battery resistance when the temperature inside the battery increases. That is, the PTC element 112 electrically connects the top cap 111 and the safety vent 113 in a normal state. However, in an abnormal state, for example, when the temperature rises abnormally, the PTC element 112 blocks the electrical connection between the top cap 111 and the safety vent 113. The thickness of the PTC element 112 may also vary depending on the material and structure, and may be, for example, 0.2 to 0.4 mm. When the thickness of the PTC element 112 is thicker than 0.4 mm, the internal resistance increases, and the battery capacity may be reduced compared to the same standard by increasing the size of the battery. Conversely, if the thickness of the PTC element 112 is thinner than 0.2 mm, it is difficult to exert a current blocking effect at a high temperature and may be destroyed by a weak external impact. Accordingly, the thickness of the PTC element 112 may be appropriately determined within the above thickness range in consideration of these points in combination.
[86]
The rechargeable battery 1 including the cap assembly 11 can provide instantaneous high output when used as a power source for a power tool such as an electric drill, and also against external physical shocks such as vibrations and drops. It can be stable.
[87]
A beading portion 14 bent from the outside to the inside is formed on the upper portion of the battery can 12. The beading part 14 places the top cap 111, the PTC element 112, the safety vent 113, and the cap assembly 11 in which the current blocking member is stacked on the top of the battery can 12, and the electrode assembly (13) to prevent the vertical movement.
[88]
As described above, the cap assembly 11 is installed on the beading portion 14 of the battery can 12 while being mounted on the crimping gasket 116. The crimping gasket 116 has a cylindrical shape with both ends open, and one end facing the inside of the battery can 12 is first bent substantially vertically toward the central axis as shown in FIG. 2, and then again It is secondly bent substantially vertically toward the inside of the battery can 12 and seated on the beading portion 14. And the other end of the crimping gasket 116 initially extends in a direction parallel to the central axis. However, when the process of forming the crimping portion 15 by bonding the cap assembly 11 and pressing the upper outer wall of the battery can 12 in the future proceeds, it is substantially vertically bent together along the shape of the crimping portion 15. To the central axis. Accordingly, the inner circumferential surface of the crimping gasket 116 is in close contact with the cap assembly 11 and the outer circumferential surface of the battery can 12.
[89]
4 is a plan view of an insulating plate 16 according to an embodiment of the present invention.
[90]
In the insulating plate 16 for a secondary battery 1 according to an embodiment of the present invention, in the insulating plate 16 inserted into the case of the secondary battery 1, the yarns of the glass fiber 161 cross each other by weft and warp Disc-shaped glass fibers 161 formed by; It includes a silicone rubber 162 coated on at least one surface of the glass fiber 161. In addition, the silicone rubber 162 is laminated on at least one surface of the glass fiber 161.
[91]
Glass Fiber (161) is manufactured in the form of a long fiber by melting glass in a platinum furnace and then drawing it through a hole with a small diameter. It has excellent heat resistance, durability, sound absorption, and electrical insulation, does not rust, and is easy to process, so it is mainly used as a building insulation, air filter, and electrical insulation. According to an embodiment of the present invention, a fabric of the glass fiber 161 in the form of a fabric in which the yarns of the glass fiber 161 are intersected by weft and warp yarns are prepared, and the glass fiber 161 The rubber 162 is coated. It is preferable that the diameter of the cross-section of one strand of the glass fiber 161 from which the yarn is unwound is approximately 4 to 15 μm.
[92]
Silicone rubber (Si Rubber, 162) is a rubber containing silicone. It is excellent in heat resistance and cold resistance, and even if left at 250°C for 3 days, the change in strength or elongation can be maintained within 10%, and elasticity can be maintained even at -45°C. Since the electrical properties do not change sensitively to temperature, they are widely used in electric, electronic, and communication fields that require heat resistance. In this silicone rubber 162, various materials are mixed and manufactured. For example, silicone polymers such as organopolysiloxane used as main raw materials, silica-based fillers, extenders to increase volume and improve oil resistance, vulcanization agents such as organic peroxides, processing aids such as low-volume silicone oligomers, or BaO, CaO , MgO, ZnO, such as various property enhancers may be mixed. Furthermore, in order to increase the flame retardancy, a flame retardant such as Al(OH) 3 , Mg(OH) 2 , BH 3 O 3 may be further included, or a pigment may be further included in order to easily inspect the quality with the naked eye. In addition, after mixing and heating the materials, the silicone rubber 162 may be manufactured by going through a vulcanization process and drying. In the vulcanization process, peroxides such as benzoyl peroxide and dicumyl peroxide may be used.
[93]
In order to manufacture the insulating plate 16 for a secondary battery according to an embodiment of the present invention, a solution is prepared by first mixing the various materials including a silicone polymer and then dissolving in a specific solvent before curing. The solvent is preferably an organic solvent capable of easily dissolving the above substances, for example, toluene, xylene, MEK, and the like.
[94]
Meanwhile, the prepared solution has a different viscosity depending on the concentration in which the silicone polymer is dissolved. In this case, if the viscosity is too low, the weft and warp threads of the fabric of the glass fiber 161 may be unwound from each other, and the coating effect may not be remarkable. Conversely, if the viscosity is too high, it does not penetrate into the voids 3 between the weft and warp yarns of the fabric of the glass fiber 161, so that the voids 3 may not be filled. The viscosity of such a solution can be experimentally selected as the optimum viscosity.
[95]
Then, the prepared solution is applied to the fabric of the glass fiber 161 (S201), and dried (S202). When applying the solution, the solution may be sprayed onto the fabric of the glass fiber 161 using a spray or the like, but it is preferable to immerse the fabric of the glass fiber 161 in a container containing the solution. Thereby, a large amount of the solution can be quickly applied to the fabric of the glass fiber 161. When the solution is applied and dried, the solvent evaporates and the silicone rubber 162 is coated on the fabric of the glass fiber 161 to form an insulating plate fabric (S203). And when the insulating plate fabric is punched into a specific shape, the insulating plate 16 according to an embodiment of the present invention is manufactured (S204). At this time, if the insulating plate 16 is installed in the cylindrical secondary battery 1, in order to be easily inserted into the battery can 12 of the cylindrical secondary battery 1, as shown in FIG. It is preferable to punch in shape. As a result, the insulating plate 16 is formed by coating the silicon rubber 162 on the glass fiber 161 having a disk shape as a whole.
[96]
5 is a side view of an insulating plate 16 according to an embodiment of the present invention.
[97]
As shown in FIG. 5, the insulating plate 16 according to an embodiment of the present invention is coated with a silicon rubber 162 on at least one surface of a glass fiber 161, so that a plurality of It has a layered form.
[98]
The solution may be applied only to one side of the fabric of the glass fiber 161, but according to an embodiment of the present invention, it is preferable to apply it to both sides. Accordingly, silicone rubber 162 is coated on both surfaces of the glass fiber 161, so that the insulating plate 16 according to an embodiment of the present invention may have a shape in which a plurality of layers are stacked. In FIG. 5, three layers are shown as being stacked, but the present invention is not limited thereto, and a separate layer may be further included between the glass fiber 161 and the silicone rubber 162.
[99]
6 is a flowchart illustrating a method of manufacturing an insulating plate 16a according to another embodiment of the present invention.
[100]
The insulating plate 16 according to an embodiment of the present invention is manufactured by coating a silicone rubber 162 on at least one surface of the glass fiber 161 once. On the other hand, the insulating plate 16a according to another embodiment of the present invention is manufactured by coating a silicone rubber 162a a plurality of times on at least one surface of the glass fiber 161a.
[101]
Hereinafter, detailed contents of each step shown in the flowchart of FIG. 6 will be described with reference to FIGS. 7 to 8.
[102]
7 is a partial cross-sectional view of a cylindrical secondary battery 1a according to another embodiment of the present invention.
[103]
Hereinafter, descriptions of the cylindrical secondary battery 1a and the insulating plate 16a according to another exemplary embodiment of the present invention will be omitted. This is for convenience of explanation and is not intended to limit the scope of rights.
[104]
An insulating plate 16a insulating the electrode assembly 13 is disposed at the top and bottom of the electrode assembly 13, respectively. The insulating plate 16a according to another embodiment of the present invention may be an upper insulating plate 16a disposed above the electrode assembly, as shown in FIG. 7, but is not limited thereto, and a lower insulating plate disposed below the electrode assembly It may be (not shown).
[105]
Insulating plate 16a according to another embodiment of the present invention is an insulating plate inserted into a case of a secondary battery 1a, comprising: a glass fiber 161a in which yarns are formed by crossing each other by weft and warp yarns; It includes a silicone rubber (162a) coated on at least one surface of the glass fiber (161a). And the silicone rubber (162a), the first silicone rubber (1621a) and first coated on at least one surface of the glass fiber (161a); And a second silicone rubber 1622a coated on the first silicone rubber 1621a. In order to manufacture the insulating plate 16a according to another embodiment of the present invention, first and second solutions are prepared by first mixing the various materials including a silicone polymer and then dissolving them in a specific solvent before curing.
[106]
Specifically, a first solution is prepared by dissolving a first silicone polymer in a first solvent, and a second solution is prepared by dissolving a second silicone polymer in a second solvent. The prepared solution has a different viscosity depending on the concentration in which the silicone polymer is dissolved. In this case, it is preferable that the viscosity of the first solution is lower than that of the second solution.
[107]
Then, the prepared first solution is applied to at least one surface of the fabric of the glass fiber 161a (S601), and dried (S602). The first solution may be applied only to one side of the fabric of the glass fiber 161a, but according to another embodiment of the present invention, it is preferable to apply it to both sides. When the first solution is applied and dried, the first solvent is evaporated and the first silicone rubber 1621a is coated on the fabric of the glass fiber 161a (S603). Thereafter, the prepared second solution is applied to at least one surface coated with the first silicone rubber 1621a (S604) and dried (S605). When the second solution is applied and dried, the second solvent is evaporated and the second silicone rubber 1622a is coated on the first silicone rubber 1621a (S606). Thereby, an insulating plate fabric is produced.
[108]
Since the first solution has a low viscosity, it can easily penetrate into the void 3 between the weft and warp yarns of the fabric of the glass fiber 161a to fill the void 3. On the other hand, the second solution has a high viscosity, so that the weft and warp yarns of the fabric of the glass fiber 161a are fixed so as not to be unwound, thereby increasing the holding force. Therefore, in the insulating plate 16a according to another embodiment of the present invention, the silicone rubber 162a is better mixed with the glass fiber 161a, and the holding force may increase.
[109]
When the insulating plate fabric is punched into a specific shape, an insulating plate 16a according to another embodiment of the present invention is manufactured (S607). At this time, if the insulating plate 16a is installed in the cylindrical secondary battery 1a, in order to be easily inserted into the battery can of the cylindrical secondary battery 1a, the insulating plate fabric is preferably punched into a disk shape.
[110]
8 is a side view of an insulating plate 16a according to another embodiment of the present invention.
[111]
In the insulating plate 16a according to another embodiment of the present invention manufactured as described above, as shown in FIG. 8, the first silicone rubber 1621a is laminated on at least one surface of the glass fiber 161a, and the first silicone A second silicone rubber 1622a is laminated on the rubber 1621a. That is, the first and second silicone rubbers 1621a and 1622a are sequentially coated to have a form in which a plurality of layers are stacked.
[112]
The first and second solutions may be applied only to one side of the fabric of the glass fiber 161a, but according to another embodiment of the present invention, it is preferable to apply both to both sides. Thus, the first and second silicone rubbers 1621a and 1622a are coated on both sides of the glass fiber 161a, so that the insulating plate 16a according to another embodiment of the present invention has a shape in which a plurality of layers are stacked. I can. In particular, since the first silicone rubber 1621a is coated before the second silicone rubber 1622a, the first silicone rubber 1621a is more laminated inside, and the second silicone rubber 1622a is more laminated outside. do. FIG. 8 shows that five layers are stacked, but the present invention is not limited thereto, and a separate layer may be further included between the glass fibers 161a and the first and second silicone rubbers 1621a and 1622a.
[113]
9 is a partial cross-sectional view of a cylindrical secondary battery 1b according to still another embodiment of the present invention.
[114]
The insulating plate 16 according to an embodiment of the present invention and the insulating plate 16a according to another embodiment of the present invention are coated with silicone rubber 162 and 162a on at least one surface of the glass fibers 161 and 161a. Thus, a plurality of layers have a laminated shape. However, in the insulating plate 16b according to another embodiment of the present invention, since the silicone rubber 162b is not laminated on the glass fiber 161a, the thickness is the same as the thickness of the glass fiber 161b.
[115]
However, since the manufacturing method of the insulating plate 16b according to another embodiment of the present invention is similar to the manufacturing method of the insulating plate 16a according to another embodiment of the present invention, the steps shown in the flowchart of FIG. Detailed contents will be described again with reference to FIGS. 9 to 16. Hereinafter, descriptions of the cylindrical secondary battery 1b and the insulating plate 16b according to another exemplary embodiment of the present invention will be omitted. This is for convenience of explanation and is not intended to limit the scope of rights.
[116]
Insulating plate 16b according to another embodiment of the present invention is an insulating plate inserted into a case of a secondary battery, comprising: a glass fiber 161b formed by crossing each other with a weft and a warp yarn; It includes a silicone rubber (162b) coated on at least one surface of the glass fiber (161b). And the silicone rubber (162b), the first silicone rubber (1621b) attached to the yarns of the glass fiber (161b); The glass fiber 161b includes a second silicone rubber 1622b inserted into the void 3 formed between the yarns.
[117]
In order to manufacture the insulating plate 16b according to another embodiment of the present invention, the first solution is applied to at least one side of the fabric of the glass fiber 161b (S601), and dried (S602). According to another embodiment of the present invention, it is preferable to apply both surfaces of the glass fiber 161b fabric.
[118]
10 is a schematic diagram of a first silicone rubber 1621b coated on a fabric of a glass fiber 161b according to another embodiment of the present invention.
[119]
Meanwhile, the glass fiber 161b is formed by crossing each other in a form in which the yarns of the glass fiber 161b are orthogonal, and a void 3 is formed between the yarns of the orthogonal glass fiber 161b. In this case, the viscosity of the first solution is lower than that of the second solution, and is much lower than that of the first solution according to another embodiment of the present invention. Accordingly, the first solution is adhered only to the peripheries of the glass fiber 161b yarns forming the fabric of the glass fiber 161b.
[120]
After applying the first solution, the surface of the fabric of the glass fiber 161b is scraped using a knife or the like. Thereby, the thickness of the original fabric of the glass fiber 161b can be adjusted, and the surface of the original fabric of the glass fiber 161b can be made smooth. When the first solution is dried (S602), the first solvent is evaporated, and as shown in FIG. 10, the first silicone rubber 1621b is coated on the fabric of the glass fiber 161b (S603). At this time, according to another embodiment of the present invention, since the first silicone rubber 1621b is in close contact with and attached only to the yarn of the glass fiber 161b, the void 3 formed between the yarns of the orthogonal glass fiber 161b ) Does not fill.
[121]
11 is a schematic diagram of a second silicone rubber 1622b coated on a fabric of a glass fiber 161b according to another embodiment of the present invention.
[122]
After that, the second solution is applied to at least one side of the fabric of the glass fiber 161b (S604), and dried (S605). At this time, the second solution has a higher viscosity than the first solution, but has a lower viscosity than the second solution according to another embodiment of the present invention. Accordingly, the second solution is inserted into the void 3 formed between the yarns of the glass fiber 161b.
[123]
After applying the second solution, the surface of the fabric of the glass fiber 161b is scraped off again using a knife or the like. Thereby, the thickness of the original fabric of the glass fiber 161b can be adjusted, and the surface of the original fabric of the glass fiber 161b can be made smooth. When the second solution is dried (S605), the second solvent is evaporated, and as shown in FIG. 11, the second silicone rubber 1622b is coated on the fabric of the glass fiber 161b (S606). At this time, according to another embodiment of the present invention, the second silicone rubber 1622b is inserted into the void 3 formed between the yarns of the orthogonal glass fiber 161b, so that the void 3 may be filled. . Thereby, an insulating plate fabric is produced.
[124]
When the insulating plate fabric is punched into a specific shape, the insulating plate 16b according to another embodiment of the present invention is manufactured (S607). At this time, if the insulating plate 16b is installed in the cylindrical secondary battery 1b, in order to be easily inserted into the battery can 12 of the cylindrical secondary battery 1b, the insulating plate fabric is preferably punched into a disk shape.
[125]
12 is a cross-sectional view taken along line A-A' of the insulating plate 16b according to another embodiment of the present invention in FIG. 11.
[126]
In the insulating plate 16b according to another embodiment of the present invention, as shown in FIG. 12, the first and second silicone rubbers 162b do not form separate layers. That is, the first silicone rubber 1621b is adhered in close contact with only the yarns of the glass fiber 161b, and the second silicone rubber 1622b is inserted into the void 3 formed between the yarns of the orthogonal glass fiber 161b. do. Therefore, since the first and second silicone rubbers 162b do not have separate layers, the thickness of the finished insulating plate 16b is the same as the thickness of the glass fibers 161b when the silicone rubber 162b is not coated. Or almost similar.
[127]
Meanwhile, as described above, an insulating plate 16b insulating the electrode assembly 13 is disposed at the upper and lower ends of the electrode assembly 13, respectively. The insulating plate 16b according to another embodiment of the present invention may be an upper insulating plate 16b disposed above the electrode assembly, as shown in FIG. 9, but is not limited thereto, and a lower part disposed below the electrode assembly. It may be an insulating plate (not shown).
[128]
When the insulating plate 16b according to another embodiment of the present invention is used as an upper insulating plate, properties such as heat resistance and chemical resistance are improved, so that thermal and chemical stability can be secured. On the other hand, when used as a lower insulating plate, not only can heat and chemical stability be ensured, but also a heat transfer path spreading out from the lower portion of the electrode assembly 13 is blocked. Conventionally, the lower separator of the electrode assembly 13 may be lost due to heat spreading through the negative electrode tab of the electrode assembly 13, and accordingly, an edge short of the lower portion of the electrode assembly 13 occurs. Could. However, since the insulating plate 16b according to another embodiment of the present invention is used as the lower insulating plate to block the heat transfer path spreading out from the lower portion of the electrode assembly 13, the edge of the lower portion of the electrode assembly 13 is shorted. Short) can be prevented.
[129]
13 is a SEM photograph taken at 1500 times magnification by actually manufacturing an insulating plate 16b according to another embodiment of the present invention, and FIG. 14 is a result of actually manufacturing an insulating plate 16b according to another embodiment of the present invention. , Is a SEM photograph taken at 1000 times magnification, and FIG. 15 is an SEM photograph taken at 200 times magnification by actually manufacturing an insulating plate 16b according to another embodiment of the present invention, and FIG. 16 is another embodiment of the present invention It is a SEM photograph taken at 40 times magnification by actually manufacturing the insulating plate 16b according to.
[130]
In FIGS. 13 and 14, large and round shapes are cross-sections of the yarns of the glass fiber 161b, and materials attached around the yarns of the glass fiber 161b are the silicone rubber 162b.
[131]
13 and 14, a first silicone rubber 1621b is adhered in close contact between the yarns of the glass fiber 161b. And, as shown in FIGS. 15 and 16, the silicone rubber 162b does not form a separate layer.
[132]
In FIGS. 13 to 16, the gap 3 between the yarns of the glass fiber 161b and the second silicone rubber 1622b are not taken in the SEM photograph until the state that the gap 3 is inserted. However, considering that the silicone rubber 162b does not form a separate layer even though the second silicone rubber 1622b is coated on the glass fiber 161b, the second silicone rubber 1622b is not in the void 3 It can be determined that it is inserted.
[133]
On the other hand, after actually manufacturing the insulating plate (16b) according to another embodiment of the present invention, the composition ratio is measured as follows.
[134]
[135]
[Table 1]
Substance name Composition ratio (wt%)
Glass Fiber (Fabric) 70 to 80
Siloxanes and silicones, di-Me, vinyl group-terminated 10 to 15
Dimethylvinylated and trimethylated silica 0 to 5
Aluminum trihydroxide 10 to 15
Titanium dioxide 0 to 5
[136]
[137]
Table 1 shows the composition ratio of the insulating plate of the manufacturing example.
[138]
As shown in Table 1, the composition ratio of the glass fiber is 70 to 80 wt%, and the composition ratio of the silicone rubber is 20 to 30 wt%. In particular, the main chains of silicone polymers such as Siloxanes and silicones, di-Me, and vinyl group-terminated are 10 to 15 wt%, and dimethylvinylated and trimethylated silica are 0 to 5 wt%. That is, when these are combined, the composition ratio of the silicone polymer is 10 to 20 wt%. In addition, aluminum trihydroxide, a flame retardant, is 10 to 15 wt%, and titanium dioxide, a pigment, is 0 to 5 wt%. In other words, since the minimum values ​​of dimethylvinylated and trimethylated silica and titanium dioxide are 0 wt%, they do not need to be included at all.
[139]
[140]
In an insulating plate for a secondary battery according to an embodiment of the present invention, in the insulating plate inserted into a case of a secondary battery, the glass fiber yarns are formed by crossing each other by weft and warp; It includes a silicone rubber coated on at least one side of the glass fiber.
[141]
Even when the insulating plate for a secondary battery is heated to a temperature of 600° C. or higher, even 950° C. or higher, the mass loss due to thermal decomposition may be 10 to 15 wt%, preferably 12 to 14 wt%. Therefore, the insulating plate for a secondary battery according to an embodiment of the present invention has excellent heat resistance.
[142]
In addition, when the insulating plate for a secondary battery is impregnated in an electrolyte containing 10 wt% or more of lithium bis (fluorosulfonyl) imide (LIFSI), and stored at 72° C. for 1 week or more, the above The reduction amount of lithium bis(fluorosulfonyl)imide (LIFSI) may be 1 to 3 wt% or less, preferably 1.5 to 2.5 wt% or less. Therefore, the insulating plate for a secondary battery according to an embodiment of the present invention has excellent chemical resistance.
[143]
In addition, when a secondary battery is manufactured using the insulating plate for a secondary battery according to an exemplary embodiment of the present invention, when the secondary battery explodes by heating at a temperature of 600° C. or higher, a pin hole may not be formed in the battery case. Therefore, the insulating plate for a secondary battery according to an embodiment of the present invention is also excellent in safety.
[144]
In addition, when the insulating plate for a secondary battery according to an embodiment of the present invention is stretched to both sides, the tensile strength is 120 to 150 N/mm 2 , preferably the tensile strength is 130 to 140 N/mm 2 , and the elongation is 5 to 10%, preferably the elongation may be 7 to 8%. Therefore, the insulating plate for a secondary battery according to an embodiment of the present invention has excellent tensile strength and elongation.
[145]
[146]
[147]
Manufacturing example
[148]
A glass fiber fabric having a width of 1,040 mm, a length of 300,000 mm, and a thickness of 0.3 mm was prepared. In addition, Siloxanes and silicones, di-Me, vinyl group-terminated 12 kg, and Dimethylvinylated and trimethylated silica 4 kg were added to 20 kg of toluene solvent as the main chain of the silicone polymer, and aluminum trihydroxide 13 as a flame retardant. kg was added. In addition, by adding 3 kg of titanium dioxide as a dye, 52 kg of the first solution was prepared.
[149]
After each roller was placed on both sides of the glass fiber fabric, a knife was placed on the top of each roller. Then, the first solution was put in the barrel, and the roller was rotated to immerse the glass fiber fabric in the first solution. While rotating the roller in reverse to take out the glass fiber fabric, the knife scraped off the first solution remaining on the surface of the glass fiber fabric. Then, a glass fiber fabric was inserted into the drying furnace, and the first solution was dried at 170° C. for 5 minutes.
[150]
Meanwhile, to 10 kg of toluene solvent, Siloxanes and silicones, di-Me, 12 kg of vinyl group-terminated, and 3 kg of dimethylvinylated and trimethylated silica were added as the main chain of the silicone polymer, and aluminum trihydroxide 13 was added as a flame retardant. kg was added. In addition, 3 kg of titanium dioxide was further added as a colorant to prepare 41 kg of a second solution.
[151]
After each roller was placed on both sides of the glass fiber fabric, a knife was placed on the top of each roller. Then, the second solution was put in the container, and the roller was rotated to immerse the glass fiber fabric in the second solution. While rotating the roller in reverse to take out the glass fiber fabric, the knife scraped off the second solution remaining on the surface of the glass fiber fabric. Then, a glass fiber fabric was inserted into the drying furnace, and the second solution was dried at 170° C. for 5 minutes.
[152]
When the insulating plate fabric was prepared in this way, it was inserted into a punching equipment, and punched into a disk shape having a diameter of 20 mm to prepare the insulating plate of the preparation example.
[153]
[154]
Comparative Example 1
[155]
Using the electrospinning method, PET was prepared as a raw material for PET with a nonwoven fabric size of 30 mm in width, 30 mm in length, and 0.3 mm in thickness.
[156]
When the insulating plate fabric was prepared in this way, it was inserted into a punching equipment, and punched into a disk shape having a diameter of 20 mm, thereby manufacturing the insulating plate of Comparative Example 1.
[157]
[158]
Comparative Example 2
[159]
A glass fiber fabric having a width of 270 mm, a length of 270 mm, and a thickness of 0.3 mm was prepared. In addition, a solution of 20 kg was prepared by adding 5 kg of phenol resin and 5 kg of aluminum trihydroxide to 10 kg of a toluene solvent.
[160]
Heat and pressure were applied using a hot press in the state of overlapping the three impregnated fabrics, and through this, a phenolic insulating plate, which had been cured, was manufactured.
[161]
When the insulating plate fabric was prepared in this way, it was inserted into a punching equipment, and punched into a disk shape having a diameter of 20 mm to prepare the insulating plate of Comparative Example 2.
[162]
[163]
[164]
Method of measuring physical properties
[165]
1. Heat resistance
[166]
The insulating plates of Preparation Example, Comparative Example 1, and Comparative Example 2 were respectively inserted into a heat resistance tester (model: TGA Q500) of TA instruments, and heat was gradually applied at a temperature range of 25 to 950°C and a temperature increase rate of 10°C/min. And, by measuring the mass of each insulating plate in real time, the amount of mass loss due to pyrolysis was confirmed.
[167]
[168]
2. Chemical resistance
[169]
An electrolyte is prepared by mixing a salt and an additive in a solvent. The solvent is prepared by mixing EC (ethylene carbonate, Ethylene Carbonate), DMC (dimethyl carbonate, Dimethyl Carbonate), and EMC (ethyl methyl carbonate, Ethyl Methyl Carbonate), and as a salt LiPF6 (lithium hexafluorophosphate, Lithium hexafluorophosphate), LiFSI (Lithium bis(fluorosulfonyl)imide, Lithium bis(fluorosulfonyl)imide) and various additives were mixed.
[170]
The insulating plates of Preparation Example, Comparative Example 1, and Comparative Example 2 were respectively impregnated in the prepared electrolyte solution, and stored at 72° C. for one week. And, after removing the respective insulating plates, NMR and GC analysis by injecting the electrolyte samples into NMR equipment (manufacturer Varian, model name EQC-0279) and GC-MS equipment (manufacturer SHIMADZU, model GC2010 Plus/QP2020, EQC-0291) By performing, the composition ratio and reaction by-products of each electrolyte solution sample were analyzed.
[171]
[172]
3. Flame propagation
[173]
In this experiment, the insulating plates of Comparative Examples 1 and 2 were not tested, but only the insulating plates of Preparation Example were tested. Thereby, it was confirmed whether the insulating plate of the manufacturing example satisfies the flame propagation performance standard. The test criteria are in accordance with IMO RESOLUTION MSC.307(88).
[174]
Specifically, the insulating plate of the manufacturing example is installed in the equipment having the main heat source and the auxiliary heat source, and the flame is applied. As the main heat source, a 483 mm wide by 284 mm long radiant heat plate is used to generate a flame using 99.99% pure methane gas as fuel. At this time, the heat quantity is 50.5 kW/m 2 at the 50 mm point and 23.9 kW/m 2 at the 350 mm point . And as an auxiliary heat source, the length of the pilot flame is about 230 mm, and the flame is generated using propane gas as a fuel.
[175]
First, in order to standardize the operation of the equipment, after installing the adjustment test piece, the radiant heat plate and the pilot flame were ignited, and the chimney signal value was continuously stable for at least 180 seconds. When the signal value stabilized, the adjustment test piece was removed, and the insulating plate of the above preparation example was installed within 10 seconds. Then, the chimney signal value was continuously measured, and the time at which the tip of the flame reached every 50 mm point of the insulating plate of Preparation Example, the point at which the flame extinguished, and the time at that time were recorded, respectively.
[176]
If, after 600 seconds of the start of the test, it was not ignited, or 180 seconds passed after the flame was extinguished, the insulating plate of the preparation example was removed and a standard test piece was installed again. A total of three insulating plates of Preparation Example were manufactured, and this process was repeated a total of three times.
[177]
[178]
4. Stability
[179]
A secondary battery was manufactured using the insulating plates of Preparation Example, Comparative Example 1, and Comparative Example 2, and all were fully charged. In addition, when the secondary batteries are placed in a heating furnace maintained at 600° C. and heated for 3 to 5 minutes, the secondary batteries explode. In addition, after cooling the exploded secondary batteries at room temperature, the cap assembly was disassembled to check whether a pinhole occurred in the upper edge of the battery can.
[180]
[181]
5. Tensile strength and elongation
[182]
Instron's Universal Testing Machine (UTM, Model 3340) is fixed to the insulating plates of the above Manufacturing Example, Comparative Example 1, and Comparative Example 2 to the upper and lower jig. Then, the required force was measured while stretching at a speed of 300 mm/min, and this force was evaluated as tensile strength. In addition, the ratio of the length stretched by this tensile strength was evaluated as the elongation rate. These experiments were conducted twice, and the average of each result was calculated.
[183]
[184]
Physical property measurement result
[185]
1. Heat resistance
[186]
[Table 2]
Temperature range 0 ~ 320 ℃ 320 ~ 600 ℃ 600 ~ 700 ℃ Residue
Manufacturing example 3.8 wt% 9.3 wt% 0.3 wt% 86.6 wt%
Comparative Example 1 - 100 wt% - 0 wt%
Comparative Example 2 40.5 wt% - 59.5 wt%
[187]
[188]
17 is a graph showing a result of a heat resistance test for an insulating plate according to Preparation Example of the present invention, and FIG. 18 is a graph showing a result of a heat resistance test for an insulating plate according to Comparative Example 2. In addition, Table 2 shows the mass loss and remaining mass of each insulating plate according to the temperature section.
[189]
As shown in Fig. 17, the mass of the insulating plate of the manufacturing example gradually decreased step by step. In addition, the reduced mass width was expressed as a numerical value, and is shown in Table 2 above. As shown in Table 2, the insulating plate of the Preparation Example was found to have a mass loss of 3.8 wt% in the 0 ~ 320 ℃ section, 9.3 wt% in the 320 ~ 600 ℃ section, and 0.3 wt% in the 600 ~ 700 ℃ section.
[190]
On the other hand, as shown in FIG. 18, the mass of the insulating plate of Comparative Example 2 continuously decreased up to 600° C., and in particular, the mass decreased rapidly in the 320 ~ 600° C. section. As shown in Table 2, the insulating plate of Comparative Example 2 was found to have a mass loss of 40.5 wt% in the range of 0 ~ 600 ℃.
[191]
On the other hand, when the insulating plate of Comparative Example 1 reaches 600° C., all of them are burned and 100 wt% of the mass is lost, and since they are burned rapidly, the graph could not be shown.
[192]
Therefore, it was confirmed that the insulating plate of Preparation Example had the least amount of mass loss due to thermal decomposition at 600°C or higher, 13.4 wt%, and even had thermal stability up to 950°C.
[193]
[194]
2. Chemical resistance
[195]
[Table 3]
LiPF6 LiFSI Remaining ingredients
Ref. 9.5 11.4 79.1
Manufacturing example 6.5 9.3 84.2
Comparative Example 1 9.4 11.1 79.5
Comparative Example 2 7.8 0.8 91.4
[196]
[197]
19 is a photograph showing the appearance of each electrolyte sample after a chemical resistance test, and FIG. 20 is a graph showing the results of a GC-MS experiment for each electrolyte sample. And Table 3 is a composition ratio of the components of each electrolyte sample.
[198]
As shown in Table 3, LiPF6 and LiFSI were relatively decreased in all samples, and the remaining components had a strong tendency to increase relatively. However, this does not mean that the absolute mass has not changed, and thus LiPF6 and LiFSI have been decomposed to change into the remaining components of the electrolyte. Since the numerical values ​​in Table 3 are relative mass ratios, it simply means that LiPF6 and LiFSI have been decomposed relatively more than the rest of the components.
[199]
As shown in Table 3, the insulating plate according to the manufacturing example of the present invention is Ref. Compared with the electrolyte, LiPF6 decreased by 3 wt% and LiFSI decreased by 2.1 wt%. However, the insulating plate according to Comparative Example 1 reduced LiPF6 by 0.1 wt% and LiFSI by 0.3 wt%, and the insulating plate according to Comparative Example 2 decreased LiPF6 by 1.7 wt% and LiFSI by 10.6 wt%. That is, the LiFSI decreased the most in the insulating plate of Comparative Example 2, which indicates that the insulating plate of Comparative Example 2 exhibited the most active chemical reaction.
[200]
Even with reference to the photograph of FIG. 19, it can be confirmed visually that the color of the electrolyte contained in the insulating plate of Comparative Example 2 changed the most, and also in the graph of FIG. 20, in the electrolyte solution containing the insulating plate of Comparative Example 2, Since many by-products that did not exist in the initial stage were detected, it was confirmed that the insulating plate of Comparative Example 2 was the most vulnerable to chemical resistance.
[201]
Therefore, it was confirmed that the insulating plate of Preparation Example was more excellent in chemical resistance than the insulating plate of Comparative Example 2.
[202]
However, the insulating plate of Comparative Example 1 was the most excellent in chemical resistance. However, in the heat resistance test, since the insulating plate of Comparative Example 1 was the most weak in heat resistance, it was confirmed that the insulating plate of Preparation Example was excellent in both heat resistance and chemical resistance.
[203]
[204]
3. Flame propagation
[205]
[Table 4]
Specimen number Manufacturing Example 1 Manufacturing Example 2 Manufacturing Example 3 Average standard
Average continuous heat of combustion (MJ/m 2 ) - - - - ≥1.5
Critical radiant heat flux during fire extinguishing (kW/m 2 ) 48.7 49.1 47.9 48.6 ≥20.0
Total heat release (MJ) 0.01 0.06 0.02 0.03 ≤0.7
Heat release rate (kW) 0.01 0.33 0.29 0.21 ≤4.0
Fireworks fall none none none none Will not be
[206]
[207]
[Table 5]
Specimen number Manufacturing Example 1 Manufacturing Example 2 Manufacturing Example 3
Measurement item Elapsed time (minutes:seconds) Average continuous heat of combustion (MJ/m 2 ) Elapsed time (minutes:seconds) Average continuous heat of combustion (MJ/m 2 ) Elapsed time (minutes:seconds) Average continuous heat of combustion (MJ/m 2 )
Flame reach (mm) 50 00:16 0.81 00:14 0.71 00:15 0.76
100 00:28 1.39 00:20 0.99 00:21 1.04
150 - - - - - -
Ignition time (minutes:seconds) 00:13 00:12 00:13
Digestion time (minutes:seconds) 00:54 00:31 00:50
Test time (minutes:seconds) 10:00 10:00 10:00
[208]
[209]
Table 4 shows the results of the critical radiant heat flux, total heat release, maximum heat release rate, and whether or not the flame falls when extinguishing the insulating plate of Preparation Example, and Table 5 is the result of average continuous heat of combustion for the insulating plate of Preparation Example.
[210]
The sustained heat of combustion is the time from the initial exposure of the test object until the tip of the flame reaches each point and the amount of radiant heat flow seen through the non-combustible calibration plate at the same point. And the average continuous heat of combustion is the average of the characteristic values ​​measured at different locations by the continuous continuous heat. As shown in Table 5, the average continuous heat of combustion of the insulating plate of the manufacturing example did not reach the standard of 1.5 when the flame reaching distance was 50 mm and 100 mm.
[211]
However, the insulating plates of Preparation Examples 1 to 3 started to ignite at 13 seconds, 12 seconds and 13 seconds, respectively, but were extinguished at 54 seconds, 31 seconds, and 50 seconds, respectively, and thereafter, no more ignition was performed. . Therefore, it was confirmed that the flame was not maintained in the insulating plate since it was immediately extinguished within a short time, although the average sustained heat of combustion may be low when burning. In other words, it was confirmed that the flame does not easily propagate around, so that safety can be secured.
[212]
The critical radiant heat flux during fire extinguishing refers to the heat flux at the position where the flame propagates to the farthest point on the center line of the burning test object. The recorded heat flow is the value obtained by the calibration test of the testing machine conducted using the calibration plate. As shown in Table 4, the average of the critical radiant heat flux when extinguishing the insulating plate of the manufacturing example is 48.6 kW/m 2 , which is greater than the standard 20.0 kW/m 2 , thus satisfying the standard.
[213]
The total heat release amount means the total heat release amount during the test period, and the maximum heat release rate refers to the maximum heat release amount during the test period. As shown in Table 4, the average of the total heat dissipation amount of the insulating plate of the manufacturing example is 0.03 MJ, less than the standard 0.7 MJ, and the average of the maximum heat release rate is 0.21 kW, less than the standard 4.0 kW, so the standard is satisfied. .
[214]
[215]
4. Stability
[216]
[Table 6]
Total count Number of pinhole occurrences Pinhole occurrence rate
Manufacturing example 41 0 0 %
Comparative Example 1 15 3 20%
Comparative Example 2 15 0 0 %
[217]
[218]
FIG. 21 is a photograph showing an exploded view of a secondary battery assembled with an insulating plate according to Preparation Example of the present invention after a stability test, and FIG. 22 is a view showing an exploded view of a secondary battery assembled with an insulating plate of Comparative Example 1 after a stability test. It is a photograph, and FIG. 23 is a photograph showing an exploded state of a secondary battery in which the insulating plate of Comparative Example 2 is assembled after a stability test. In addition, Table 6 shows the number and ratio of pinholes in each of the insulating plates.
[219]
As shown in FIG. 22, pinholes were generated in the secondary battery to which the insulating plate of Comparative Example 1 was assembled. Specifically, as described in Table 6, of a total of 15 secondary batteries to which the insulating plate of Comparative Example 1 was assembled, pinholes were generated in three secondary batteries.
[220]
On the other hand, as shown in FIGS. 21 and 23, it was confirmed that the insulating plate of Preparation Example and the insulating plate of Comparative Example 2 did not generate pinholes at all, so that the stability of the battery was the best.
[221]
However, since the insulating plate of Comparative Example 2 has weaker heat resistance and chemical resistance than the insulating plate of Preparation Example, it was confirmed that the insulating plate of Preparation Example was excellent in both heat resistance, chemical resistance, and stability.
[222]
[223]
5. Tensile strength and elongation
[224]
[Table 7]
Tensile strength (N/mm 2 ) Elongation (%)
One 2 Average One 2 Average
Manufacturing example 130.12 137.16 133.64 6.89 7.37 7.13
Comparative Example 1 60.3 53.4 56.9 47.0 51.0 49.0
Comparative Example 2 - - - 0 0 0
[225]
[226]
Table 7 shows the tensile strength and elongation of each insulating plate.
[227]
As shown in Table 7 , fracture occurred in the insulating plate of the production example at an average tensile strength of 133.64 N/mm 2 . And the elongation at this time was 7.13% on average.
[228]
However, the insulating plate of Comparative Example 1 was fractured at an average tensile strength of 56.9 N/mm 2 . And the elongation at this time was an average of 49.0%.
[229]
In addition, the insulating plate of Comparative Example 2 was not stretched at all to 1000 N, which is the maximum allowable weight of the universal material testing machine. Therefore, the tensile strength could not be measured, and the resulting elongation was an average of 0%.
[230]
Therefore, the insulating plate of Comparative Example 1 has a problem of low tensile strength and high elongation, and is easily deformed even with a small force. In addition, since the insulating plate of Comparative Example 2 does not have elongation properties, it is impossible to manufacture in a roll type, and accordingly, it cannot be put into a line, so continuous production is impossible, and the production speed may be lowered. However, the insulating plate of the manufacturing example can be manufactured in a roll type wound to one side because of its high tensile strength and low elongation and can be stretched to some extent.
[231]
[232]
[233]
When the silicone rubber 162 is coated on the glass fiber 161 as described above, properties such as heat resistance and chemical resistance are improved by manufacturing the insulating plate 16 for a secondary battery compared to coating with a conventional thermoplastic resin or phenol. Can be improved. In particular, phenol has a chain bond form in which the central element is carbon (C), but the silicon polymer, which is the main raw material of the silicone rubber 162, has a chain bond form in which the central element is silicon (Si). Therefore, it can have high thermal stability. In addition, dust generation is suppressed when the insulating plate 16 for a secondary battery is punched, enabling continuous production, increasing production, and reducing manufacturing cost. Furthermore, the fabric of the insulating plate before punching of the insulating plate 16 for a secondary battery has flexibility, and by winding it up to easily form a mother-roll, the insulating plate 16 for a secondary battery can be easily manufactured.
[234]
Those of ordinary skill in the art to which the present invention pertains will appreciate that the present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, it should be understood that the embodiments described above are illustrative and non-limiting in all respects. The scope of the present invention is indicated by the claims to be described later rather than the detailed description, and various embodiments derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention.
Claims
[Claim 1]
In the insulating plate inserted into a case of a secondary battery, the glass fiber yarns formed by crossing each other by weft and warp; An insulating plate for a secondary battery comprising a silicone rubber coated on at least one surface of the glass fiber.
[Claim 2]
The method of claim 1, wherein the silicone rubber comprises: a first silicone rubber attached to the glass fiber yarns; An insulating plate for a secondary battery comprising a second silicone rubber inserted into the voids formed between the glass fiber yarns.
[Claim 3]
The insulating plate for a secondary battery according to claim 2, wherein the glass fiber yarns cross each other in an orthogonal shape, and the second silicone rubber is inserted into a void formed between the orthogonal glass fiber yarns.
[Claim 4]
The insulating plate for a secondary battery according to claim 2, wherein the thickness is the same as that of the glass fiber.
[Claim 5]
The method of claim 1, wherein the silicone rubber comprises: a first silicone rubber coated on at least one side of the glass fiber; An insulating plate for a secondary battery comprising a second silicone rubber coated on the first silicone rubber.
[Claim 6]
The insulating plate for a secondary battery according to claim 5, wherein the first silicone rubber is laminated on at least one surface of the glass fiber, and the second silicone rubber is laminated on the first silicone rubber.
[Claim 7]
The insulating plate for a secondary battery according to claim 1, wherein the silicone rubber is laminated on at least one surface of the glass fiber.
[Claim 8]
The insulating plate for a secondary battery according to claim 1, wherein the glass fiber is formed in a disk shape.
[Claim 9]
The insulating plate for a secondary battery according to claim 1, wherein the silicone rubber is coated on both surfaces of the glass fiber.
[Claim 10]
The insulating plate of claim 1, wherein the glass fiber has a composition ratio of 70 to 80 wt%, and the silicone rubber has a composition ratio of 20 to 30 wt%.
[Claim 11]
The insulating plate for a secondary battery according to claim 10, wherein the silicone rubber contains a silicone polymer and a flame retardant.
[Claim 12]
The insulating plate of claim 11, wherein the silicone polymer has a composition ratio of 10 to 20 wt%, and the flame retardant has a composition ratio of 10 to 15 wt%.
[Claim 13]
The insulating plate for secondary batteries according to claim 12, wherein the silicone rubber further contains a dye.
[Claim 14]
The insulating plate for a secondary battery according to claim 13, wherein the dye has a composition ratio of 5 wt% or less.
[Claim 15]
Cylindrical battery cans; A jelly-roll type electrode assembly accommodated in the battery can; A cap assembly coupled to an upper portion of the battery can; A beading portion provided at the front end of the battery can to mount the cap assembly; A crimping part for sealing the battery can; And an insulating plate insulating the electrode assembly, wherein the insulating plate includes: glass fibers formed by intersecting each other by means of a weft and a warp yarn; And a silicone rubber coated on at least one surface of the glass fiber.
[Claim 16]
The secondary battery of claim 15, wherein the insulating plate is an upper insulating plate disposed between the electrode assembly and the cap assembly.
[Claim 17]
The secondary battery of claim 15, wherein the insulating plate is a lower insulating plate disposed between the electrode assembly and a bottom portion of the battery can.