This application claims the benefit of priority based on Korean Patent Application No. 10-2018-0118868 dated October 05, 2018, and all contents disclosed in the documents of the Korean patent application are incorporated as a part of this specification.
technical field
The present invention relates to a secondary battery.
background
[5]
Secondary batteries, unlike primary batteries, are rechargeable, and have been widely researched and developed in recent years due to their small size and large capacity. As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing.
[6]
Secondary batteries are classified into coin cells, cylindrical cells, prismatic cells, and pouch cells according to the shape of the battery case. In a secondary battery, an electrode assembly mounted inside a battery case is a charging/discharging power generating element having a stacked structure of an electrode and a separator.
[7]
The electrode assembly is a jelly-roll type in which a separator is interposed between a positive electrode and a negative electrode of a sheet-type sheet coated with an active material, and a stack type in which a plurality of positive and negative electrodes are sequentially stacked with a separator interposed therebetween. , and stacked unit cells can be roughly classified into a stack/folding type in which a long-length separation film is wound. The double jelly roll type electrode assembly is widely used because it is easy to manufacture and has the advantage of high energy density per weight.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[8]
One aspect of the present invention is to provide a secondary battery capable of securing reliability such as airtightness while reducing a manufacturing process.
[9]
Another aspect of the present invention is to provide a secondary battery in which the connection between the can and the electrode assembly can be cut when the internal pressure of the battery reaches a critical point or more.
means of solving the problem
[10]
A secondary battery according to an embodiment of the present invention includes an electrode assembly in which a first electrode, a separator, and a second electrode are alternately stacked and wound; A can having an accommodating portion accommodating the electrode assembly therein, the can including first and second cans formed in a tubular shape opened in opposite directions, and an overlapping portion between the first and second cans an insulator to insulate, wherein the first can is in direct contact with an end of the first electrode to form a first electrode terminal, and the second can is in direct contact with an end of the second electrode to form a second electrode terminal can form.
Effects of the Invention
[11]
According to the present invention, by assembling two cans in an interference fit form and connecting the positive and negative electrodes respectively, the two cans become positive and negative terminals, simplifying assembly, and ensuring reliability such as airtightness. And it is possible to easily manufacture a large-capacity medium-large battery. Accordingly, there is an effect that high productivity and low manufacturing cost are generated.
[12]
In addition, according to the present invention, when the internal pressure of the battery reaches a critical point or more, the coupling of the two cans coupled to the press-fitting can be released, and the connection of the electrode assembly coupled to the two cans can be broken. Accordingly, when there is a rapid increase in temperature and pressure inside the battery due to overcharging of the secondary battery or an external short circuit without additional safety devices, the coupling of the two cans with the force fit is released and the safety device function to perform the current blocking function. can perform
Brief description of the drawing
[13]
1 is a perspective view showing a secondary battery according to an embodiment of the present invention.
[14]
2 is an exploded perspective view illustrating a secondary battery according to an embodiment of the present invention.
[15]
3 is a cross-sectional view illustrating a secondary battery according to an embodiment of the present invention.
[16]
4 is an exploded perspective view showing a secondary battery according to another embodiment of the present invention.
[17]
5 is a cross-sectional view showing a secondary battery according to another embodiment of the present invention.
[18]
6 is a diagram illustrating a temperature analysis of a can in a secondary battery according to an embodiment of the present invention.
[19]
7 is a diagram illustrating a temperature analysis of a can in a secondary battery of a conventional secondary battery, which is a comparative example.
Modes for carrying out the invention
[20]
The objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings and preferred embodiments. In the present specification, in adding reference numbers to the components of each drawing, it should be noted that only the same components are given the same number as possible even though they are indicated on different drawings. In addition, the present invention may be embodied in several different forms and is not limited to the embodiments described herein. And, in describing the present invention, detailed descriptions of related known technologies that may unnecessarily obscure the gist of the present invention will be omitted.
[21]
[22]
1 is a perspective view illustrating a secondary battery according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view showing a secondary battery according to an embodiment of the present invention.
[23]
1 to 3 , the secondary battery 100 according to an embodiment of the present invention includes an electrode assembly 110 , and a first can 121 and a second can accommodating the electrode assembly 110 therein. A can 120 including 122 , and an insulator 123 insulating an overlapping portion between the first can 121 and the second can 122 .
[24]
[25]
3 is a cross-sectional view illustrating a secondary battery according to an embodiment of the present invention.
[26]
Hereinafter, a secondary battery according to an embodiment of the present invention will be described in more detail with reference to FIGS. 1 to 3 .
[27]
Referring to FIGS. 2 and 3 , the electrode assembly 110 is a power generating element capable of charging and discharging, and the electrode 113 and the separator 114 are assembled to form a structure in which they are alternately stacked. Here, the electrode assembly 110 may have a wound shape.
[28]
The electrode 113 may include a first electrode 111 and a second electrode 112 . The separator 114 separates and electrically insulates the first electrode 111 and the second electrode 112 . Here, the first electrode 111 and the second electrode 112 may be formed in a sheet shape, wound together with the separator 114 , and formed in a jelly roll shape. In this case, the electrode assembly 110 may be wound in a cylindrical shape, for example.
[29]
The first electrode 111 may include a first electrode current collector 111a and a first electrode active material 111b applied to the first electrode current collector 111a. In addition, the first electrode 111 may include the first electrode uncoated region 111c on which the first electrode active material 111b is not coated.
[30]
Here, the first electrode 111 is made of, for example, a positive electrode, and includes a positive electrode current collector (not shown) and a positive electrode active material (not shown) coated on the positive electrode current collector, and a positive electrode uncoated region on which the positive electrode active material is not coated is formed. can be
[31]
The positive electrode current collector may be made of, for example, aluminum foil, and the positive electrode active material may include, for example, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or at least one of these. It may consist of compounds and mixtures, and the like.
[32]
The second electrode 112 may include a second electrode current collector 112a and a second electrode active material 112b applied to the second electrode current collector 112a. In addition, the second electrode 112 may include the second electrode uncoated region 112c on which the second electrode active material 112b is not coated.
[33]
Here, the second electrode 112 is made of, for example, a negative electrode, and includes a negative electrode current collector (not shown) and a negative electrode active material (not shown) applied to the negative electrode current collector, and a negative electrode uncoated region on which the negative electrode active material is not coated is formed. can be
[34]
The negative electrode current collector may be made of, for example, a foil made of a copper (Cu) or nickel (Ni) material. The anode active material may be made of, for example, artificial graphite, lithium metal, lithium alloy, carbon, petroleum coke, activated carbon, graphite, a silicon compound, a tin compound, a titanium compound, or an alloy thereof. In this case, the negative active material may further include, for example, non-graphite-based SiO (silica, silica) or SiC (silicon carbide, silicon carbide).
[35]
The separator 114 is made of an insulating material and is alternately stacked with the first electrode 111 and the second electrode 112 . Here, the separator 114 may be positioned between the first electrode 111 and the second electrode 112 and on the outer surface of the first electrode 111 and the second electrode 112 . In this case, the separator 114 may be positioned at the outermost side in the width direction when the electrode assembly 110 is wound.
[36]
In addition, the separator 114 may be made of a flexible material. In this case, the separator 114 may be formed of, for example, a polyolefin-based resin film such as polyethylene or polypropylene having microporosity.
[37]
[38]
The can 120 may include a first can 121 and a second can 122 in which an accommodating part for accommodating the electrode assembly 110 is formed therein, and formed in a cylindrical shape opened in a direction opposite to each other.
[39]
Here, the first can 121 may be electrically connected to the first electrode 111 , and the second can 122 may be electrically connected to the second electrode 112 . The first can 121 is in direct contact with the end of the first electrode 111 to form a first electrode terminal, and the second can 122 is in direct contact with the end of the second electrode 112 to form a second electrode terminal can form.
[40]
In addition, the first can 121 and the second can 122 may be formed to correspond to each other.
[41]
In addition, the first can 121 and the second can 122 are formed in a cylindrical shape, and the inner peripheral surface of the first can 121 is formed to be larger than the outer peripheral surface of the second can 122 , so that the second can 122 is formed in a cylindrical shape. It may be inserted into the first can 121 .
[42]
In addition, in the first can 121 , a first connection portion 121a closed in one direction C1 is formed on one side portion 121b , and a first opening opened in the other direction C2 on the other side portion 121c . (121d) may be formed. The second can 122 has a second connection portion 122a closed in the other direction C2 on the other side portion 122c, and a second opening (not shown) that is opened on the one side portion 122b in the one direction C1. city) can be formed. In this case, one end of the first electrode 111 may be connected to the first connection part 121a , and the other end of the second electrode 112 may be connected to the second connection part 122a . Here, for example, the first electrode uncoated region 111c of the first electrode 111 is in direct contact with the first connection portion 121a, and the second electrode uncoated region 112c of the second electrode 112 is connected to the second It may be in direct contact with the connection part 122a.
[43]
And, for example, the first can 121 positioned on the outside may include aluminum (Al), and the second can 122 positioned on the inside may include steel. In this case, the second can 122 may be made of nickel (Ni) coated steel.
[44]
In this case, the first electrode 111 may be formed of an anode, and the second electrode 112 may be formed of a cathode.
[45]
Meanwhile, the length L1 of the electrode assembly 110 in the longitudinal direction L may be longer than the length L2 of the second can 122 in the longitudinal direction L. Accordingly, there is an effect that the end of the second can 122 does not come into contact with the first connection portion 121a. Therefore, it is possible to easily prevent a short circuit, and the insulator 123 surrounds the end of the second can 122 in order to prevent the end of the second can 122 from coming into contact with the first connection part 121a. there will be no need
[46]
Meanwhile, the length V of the overlapping section between the first can 121 and the second can 122 is greater than the diameter r1 of the first can 121 and the diameter r2 of the second can 122 . It can be formed long. Accordingly, reliability such as confidentiality can be secured.
[47]
Also, for example, the length of the first can 121 may be 70% or more of the length of the second can 122 . Here, for example, the length of the overlapping section between the first can 121 and the second can 122 may be 70% or more and less than 100% of the total length of the can 120 .
[48]
At this time, more specifically, for example, the lengths L1 and L2 in the longitudinal direction L of the first can 121 and the second can 122 have a range of 100 mm to 250 mm, respectively, and the first can 121 . A length L3 in the longitudinal direction L of the can 120 to which the second can 122 and the second can 122 are coupled may also have a range of 100 mm to 250 mm. In addition, the diameters r1 and r2 of the first can 121 and the second can 122 may be in a range of 40 mm to 60 mm, respectively. If such a range is satisfied, effective heat dissipation is possible, and it may be easy to secure reliability such as airtightness.
[49]
[50]
The insulator 123 may include an insulating material to insulate an overlapping portion between the first can 121 and the second can 122 .
[51]
In addition, the insulator 123 may include an insulating polymer. In this case, the insulating polymer may be, for example, a polymer. In this case, the polymer may be specifically made of, for example, any one of polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET).
[52]
In addition, the insulator 123 may be provided on the outer peripheral surface of the second can 122 in the form of any one of tubing, wrapping, and coating.
[53]
Here, for example, in the form of tubing, the insulator 123 may be provided on the outer circumferential surface of the second can 122 in the form of a tube, and in the form of wrapping, the insulator 123 as the second can ( 122) may be in the form of surrounding the outer peripheral surface. In addition, the coating may be in the form of forming a coating layer by coating an insulating material on the outer peripheral surface of the second can 122 .
[54]
In this case, the first can 121 and the second can 122 may be coupled to each other in the form of an interference fit. That is, the second can 122 provided with the insulator 123 on the outer circumferential surface may be press-fitted to the inner circumferential surface of the first can 121 .
[55]
[56]
The secondary battery 100 according to an embodiment of the present invention configured as described above is assembled by assembling the first can 121 and the second can 122 in the form of an interference fit to form the first electrode 111 and the second electrode 112 . ), the first can 121 and the second can 122 become the first electrode terminal and the second electrode terminal, so assembly is simplified, reliability such as airtightness can be secured, and large capacity A medium and large-sized battery can be easily manufactured. Accordingly, there is an effect that high productivity and low manufacturing cost are generated.
[57]
In addition, when the internal pressure of the secondary battery 100 reaches a critical point or more, the coupling of the first can 121 and the second can 122 that are press-fitted is released, and the first can 121 and the second can are released. The connection of the electrode assembly 110 coupled to the 122 may be cut off. That is, when the internal pressure of the battery reaches the critical point or more, the first can 121 and the second can 122 receive pressure to be spaced apart from each other, the first can 121 moves in one direction C1, and the second can 121 The can 122 may be moved in the other direction C2 and the interference fit between the first can 121 and the second can 122 may be released. In this case, the ends of the first electrode 111 and the second electrode 112 of the electrode assembly 110 in direct contact with the first can 121 and the second can 122 and the first can 121 or the second can Since the contact of the can 122 is dropped, the current may be cut off. Therefore, when there is a rapid increase in the temperature and pressure inside the battery due to overcharging and external short circuit of the secondary battery 100 without an additional safety device, the first can 121 and the second can 122 that are press-fitted cannot be combined. It is released and a safety device function that performs a current blocking function can be exerted.
[58]
[59]
Hereinafter, a secondary battery according to another embodiment will be described.
[60]
4 is an exploded perspective view showing a secondary battery according to another embodiment of the present invention, and FIG. 5 is a cross-sectional view showing a secondary battery according to another embodiment of the present invention.
[61]
Referring to FIG. 4 , a secondary battery 200 according to another embodiment of the present invention includes an electrode assembly 210 , and a first can 221 and a second can 222 accommodating the electrode assembly 210 therein. and an insulator 223 that insulates an overlapping portion between the can 120 including the can 120 and the first can 221 and the second can 222 .
[62]
The secondary battery 200 according to another embodiment of the present invention has a material of the first can 221 and the second can 222 and a first electrode ( 211) and the second electrode 212 have a difference in polarity. Accordingly, in this embodiment, content overlapping with the embodiment will be briefly described, and differences will be mainly described.
[63]
[64]
In more detail, referring to FIGS. 4 and 5 , in the secondary battery 200 according to another embodiment of the present invention, the electrode assembly 210 has a structure in which the electrodes 213 and the separator 214 are assembled and alternately stacked. to form Here, the electrode assembly 210 may have a wound shape.
[65]
The electrode 213 may include a first electrode 211 and a second electrode 212 .
[66]
The first electrode 211 may include a first electrode current collector 211a and a first electrode active material 211b applied to the first electrode current collector 211a. In addition, the first electrode 211 may include the first electrode uncoated region 211c on which the first electrode active material 211b is not coated.
[67]
The second electrode 212 may include a second electrode current collector 212a and a second electrode active material 212b applied to the second electrode current collector 212a. In addition, the second electrode 212 may include the second electrode uncoated region 212c on which the second electrode active material 212b is not coated.
[68]
The can 220 may include a first can 221 and a second can 222 that are formed in a tubular shape having an accommodating portion accommodating the electrode assembly 210 therein and open in opposite directions.
[69]
Here, the first can 221 may be electrically connected to the first electrode 211 , and the second can 222 may be electrically connected to the second electrode 212 .
[70]
In addition, the first can 221 and the second can 222 are formed in a cylindrical shape, and the inner peripheral surface of the first can 221 is formed to be larger than the outer peripheral surface of the second can 222 , so that the second can 222 is formed in a cylindrical shape. It may be inserted into the first can 221 .
[71]
In addition, in the first can 221 , a first connection part 221a closed in one direction C1 is formed on one side part 221b , and a first opening part opened in the other direction C2 on the other side part 221c . (221d) may be formed. The second can 222 has a second connection portion 222a closed in the other direction C2 on the other side portion 222c, and a second opening (not shown) that is opened on one side portion 222b in the one direction C1. ) can be formed. In this case, one end of the first electrode 211 may be connected to the first connection part 221a , and the other end of the second electrode 212 may be connected to the second connection part 222a. Here, for example, the first electrode uncoated region 211c of the first electrode 211 directly contacts the first connection portion 221a, and the second electrode uncoated region 212c of the second electrode 212 is connected to the second It may be in direct contact with the connection part 222a.
[72]
Meanwhile, for example, the first can 221 positioned on the outside may include steel, and the second can 222 positioned on the inside may include aluminum. In this case, the first can 221 may be made of nickel (Ni) coated steel.
[73]
In this case, the first electrode 211 may be formed as a cathode, and the second electrode 212 may be formed as an anode.
[74]
The insulator 223 may include an insulating material to insulate an overlapping portion between the first can 221 and the second can 222 .
[75]
[76]
< Preparation example >
[77]
6 is a diagram illustrating a temperature analysis of a can in a secondary battery according to an embodiment of the present invention.
[78]
Referring to FIG. 6( a ), a can including a first can and a second can, which are formed in a cylindrical shape opened in mutually facing directions, was manufactured. Here, the first can positioned outside was formed to include aluminum, and the second can positioned to the inside was formed to include steel. Here, the thickness of the first can is 0.2t (t=0.1mm), and the thickness of the second can is 0.2t.
[79]
In addition, an insulator was included to insulate the overlapping portion between the first can and the second can. At this time, the insulator was made of a PP polymer material and formed to a thickness of 0.1t (t=0.1mm).
[80]
In addition, the length of the outer can as the first can is 200 mm, the length of the inner can as the second can is 199 mm, and the length of the insulator is 195 mm. In Fig. 6(a), blue is the inner can (second can), purple is the outer can (first can), and gray is the insulator.
[81]
[82]
< Comparative Example >
[83]
7 is a diagram illustrating a temperature analysis of a can in a secondary battery of a conventional secondary battery, which is a comparative example.
[84]
Referring to FIG. 7( a ), a can was manufactured in the same manner as in Preparation Example, except that the outer can had a length of 120 mm, the inner can had a length of 120 mm, and the insulator had a length of 50 mm. In Fig. 7(a), blue is the inner can, purple is the outer can, and gray is the insulator.
[85]
[86]

[87]
The temperature analysis was shown in FIGS. 6(b) and 7(b) by setting the initial temperature to 50°C.
[88]
Here, natural convection conditions were applied only to the circumference (purple) of the outer can to compare the temperature over time.
[89]
As a result of the experiment, after 3600 sec, the maximum temperature of the can with the structure presented in Preparation Example was 39°C, but the maximum temperature of the can of Comparative Example was 43°C. Accordingly, it can be confirmed that the can structure presented in the manufacturing example is excellent in terms of heat dissipation characteristics.
[90]
[91]
Although the present invention has been described in detail through specific examples, it is intended to describe the present invention in detail, and the secondary battery according to the present invention is not limited thereto. It will be said that various implementations are possible by those of ordinary skill in the art within the technical spirit of the present invention.
[92]
In addition, the specific protection scope of the invention will be made clear by the appended claims.
Claims
[Claim 1]
an electrode assembly in which a first electrode, a separator, and a second electrode are alternately stacked and wound; a can having an accommodating portion accommodating the electrode assembly therein, the can including a first can and a second can formed in a tubular shape opened in a direction opposite to each other; and an insulator insulating an overlapping portion between the first can and the second can, wherein the first can is in direct contact with an end of the first electrode to form a first electrode terminal, and the second can is in direct contact with an end of the second electrode to form a second electrode terminal.
[Claim 2]
The secondary battery according to claim 1, wherein the insulator comprises an insulating polymer.
[Claim 3]
The secondary battery of claim 1 , wherein the first can and the second can are formed in a shape corresponding to each other.
[Claim 4]
The method according to claim 1, wherein the first can and the second can are formed in a cylindrical shape, and an outer circumferential surface of the first can is formed to be larger than an inner circumferential surface of the second can, so that the second can is inserted into the first can. secondary battery.
[Claim 5]
The secondary battery according to claim 4, wherein the insulator is provided on an outer circumferential surface of the second can in the form of any one of tubing, wrapping, and coating.
[Claim 6]
The secondary battery according to claim 5, wherein the first can and the second can are coupled to each other in an interference fit.
[Claim 7]
The method according to claim 4, wherein the first can has a first opening opened in the other direction on the other side, a first connection part closed in one direction is formed on one side of the can, and the second can is formed on one side in one direction. a second opening is formed, a second connection part closed in the other direction is formed on the other side, one end of the first electrode is directly connected to the first connection part, and the other end of the second electrode is A secondary battery directly connected to the second connection part.
[Claim 8]
The secondary battery of claim 4 , wherein the first can includes aluminum, and the second can includes steel.
[Claim 9]
The secondary battery according to claim 8, wherein the first electrode is formed of a positive electrode, and the second electrode is formed of a negative electrode.
[Claim 10]
The rechargeable battery of claim 4 , wherein the first can includes steel, and the second can includes aluminum.
[Claim 11]
The secondary battery according to claim 10, wherein the first electrode is formed of a negative electrode, and the second electrode is formed of a positive electrode.
[Claim 12]
The rechargeable battery of claim 7 , wherein a length of the electrode assembly in a longitudinal direction is longer than a length of the second can in a longitudinal direction.
[Claim 13]
The rechargeable battery of claim 7 , wherein a length of a section overlapping between the first can and the second can is longer than diameters of the first can and the second can.
[Claim 14]
The secondary battery of claim 7 , wherein the length of the first can is 70% or more of the length of the second can.
[Claim 15]
The secondary battery of claim 14 , wherein a length of an overlapping section between the first can and the second can is 70% or more and less than 100% of the total length of the can.
[Claim 16]
The method according to claim 15, wherein the longitudinal length of the first can and the second can range from 100 mm to 250 mm, respectively, and the longitudinal length of the can to which the first can and the second can are combined is also 100 mm to 250 mm. A secondary battery having a range of, and the diameter of the first can and the second can each having a range of 40mm to 60mm.