Title of Invention: Secondary Battery and Device Containing Same
technical field
[One]
Cross-Citation with Related Application(s)
[2]
This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0129946 dated October 18, 2019, and all contents disclosed in the literature of the Korean patent application are incorporated as a part of this specification.
[3]
The present invention relates to a secondary battery and a device including the same, and more particularly, to a secondary battery including a jelly roll electrode assembly and a device including the same.
background
[4]
Recently, an increase in the price of an energy source due to the depletion of fossil fuels, interest in environmental pollution is increasing, and the demand for an eco-friendly alternative energy source is becoming an indispensable factor for future life. Accordingly, research on various power production technologies such as nuclear power, solar power, wind power, and tidal power continues, and power storage devices for using the generated energy more efficiently are also of great interest.
[5]
In particular, as technology development and demand for mobile devices increase, the demand for batteries as an energy source is rapidly increasing, and accordingly, a lot of research on batteries capable of meeting various needs is being conducted.
[6]
Typically, there is a high demand for lithium secondary batteries, such as lithium ion batteries and lithium ion polymer batteries, which have advantages such as high energy density, discharge voltage, and output stability.
[7]
In addition, depending on the shape of the battery case, the secondary battery consists of a cylindrical battery and a prismatic battery in which the electrode assembly is embedded in a cylindrical or prismatic metal can, and a pouch-type battery in which the electrode assembly is embedded in a pouch-type case of an aluminum laminate sheet. are classified
[8]
In addition, secondary batteries are classified according to the structure of the electrode assembly in which a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode are stacked.
[9]
Typically, a jelly roll (winding type) electrode assembly in which a long sheet-shaped anode and anode are wound in a state in which a separator is interposed, and a plurality of cathodes and anodes cut in units of a predetermined size are interposed with a separator and a stack-type (stacked-type) electrode assembly that is sequentially stacked in one state.
[10]
Recently, in order to solve the problems of the jelly roll type electrode assembly and the stack type electrode assembly, it is an electrode assembly having an advanced structure, which is a mixture of the jelly roll type and the stack type. A stack/folding electrode assembly having a structure in which the unit cells stacked in a state of being placed on a separation film are sequentially wound has been developed.
[11]
1 is an exploded perspective view showing a state before the conventional jelly roll electrode assembly 10 is wound.
[12]
Referring to FIG. 1 , a conventional jelly roll electrode assembly 10 inserted into a secondary battery includes a first electrode sheet 20 , a second electrode sheet 30 , and a first electrode sheet 20 and a second electrode sheet ( 30) and a separation membrane 40 interposed therebetween. In addition, in order to prevent the first electrode sheet 20 and the second electrode sheet 30 from contacting each other when wound in the form of a jelly roll, a separator 40 is additionally disposed under the second electrode sheet 30 it is preferable
[13]
Here, the first electrode sheet 20 and the second electrode sheet 30 may correspond to a positive electrode sheet and a negative electrode sheet, respectively.
[14]
The active material layer 22 is formed on the first electrode sheet 20 , and the first electrode tab 21 may be bonded to the uncoated region 23 in which the active material layer 22 is not formed by welding or the like.
[15]
Similarly, the active material layer 32 is formed on the second electrode sheet 30 , and the second electrode tab 31 may be bonded to the uncoated region 33 in which the active material layer 32 is not formed by welding or the like. there is.
[16]
FIG. 2 is a perspective view showing a state in which the electrode assembly 10 of FIG. 1 is wound.
[17]
Referring to FIG. 2 , the first electrode tab 21 and the second electrode tab 31 extend in an upper direction (Z-axis direction) and a lower direction (opposite to the Z-axis direction) of the wound electrode assembly 10 .
[18]
At this time, when the wound electrode assembly 10 is viewed from above, the first electrode tab 21 and the second electrode tab 31 are inevitably positioned on either side with respect to the central axis of the electrode assembly 10 . . In particular, in FIG. 2 , it is illustrated that the first electrode tabs 21 are deviated in a direction opposite to the X-axis with respect to the central axis of the electrode assembly 10 .
[19]
As such, the outer diameter of the electrode assembly 10 when viewed from above is increased by the electrode tabs 21 and 31 , and inevitably takes an asymmetrical shape.
[20]
When an impact test is performed on the secondary battery in which the electrode assembly 10 is accommodated, results are derived differently depending on the positions of the electrode tabs 21 and 31, and the electrode tabs 21 and 31 are positioned There is a problem that the electrode assembly 10 is pushed in a direction not to do so. This is a problem that may appear when the secondary battery is exposed to an external shock as well as an impact test.
[21]
In addition, during charging and discharging of the electrode assembly 10, a phenomenon in which the electrode assembly 10 swells may occur. Due to this asymmetric shape, the shape is based on the portion where the electrode tabs 21 and 31 are not located. A problem of distortion may occur.
[22]
Although the first electrode tab 21 and the second electrode tab 31 are thin, the first electrode sheet 20, the second electrode sheet 30, and the separator 40 are usually wound several tens of times. Since the above is made, the asymmetry and distortion of the electrode assembly 10 become more prominent, and eventually, a problem that cannot be ignored may be caused.
[23]
Accordingly, there is a very high need for a technology capable of solving these problems.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[24]
Embodiments of the present invention are proposed to solve the above problems of the previously proposed methods, and even when the electrode assembly is wound, it is an object of the present invention to prevent asymmetry or distortion of the shape due to the electrode tab from occurring.
[25]
However, the problems to be solved by the embodiments of the present invention are not limited to the above-described problems and may be variously expanded within the scope of the technical idea included in the present invention.
means of solving the problem
[26]
A secondary battery according to an embodiment of the present invention includes: a jelly roll electrode assembly in which a first electrode sheet, a second electrode sheet, and a separator interposed between the first electrode sheet and the second electrode sheet are wound together; and a first electrode tab bonded to the uncoated portion of the first electrode sheet and positioned at a central portion of the jelly roll electrode assembly, wherein the first electrode tab includes a joint portion bonded to the uncoated portion and an external portion from the joint portion. It includes an extended extension, the width of the junction is wider than the width of the extension, and the junction is wound at least 3/4 times and not more than once in the center of the jelly roll electrode assembly.
[27]
The uncoated portion of the first electrode sheet may be formed at one end of the first electrode sheet.
[28]
The first electrode sheet may be wound in a direction in which the first electrode tab is located.
[29]
The joint may be wound once.
[30]
One end of the joint portion may be in contact with the other end opposite to the one end.
[31]
A stepped portion may be formed at the one end of the bonding portion, and a protrusion engaged with the stepped portion may be formed at the other end of the bonding portion.
[32]
An indentation groove may be formed at the one end of the junction part, and an indentation groove insertion part inserted into the indentation groove may be formed at the other end of the junction part.
[33]
The indentation groove and the indentation groove insertion part may be spaced apart from a surface to which the joint part is joined to the uncoated part and a surface opposite thereto.
[34]
The joint portion may include a trimming portion formed on at least one of corners of the joint portion.
[35]
The extension portion may extend in a direction of an upper side of the uncoated portion, and the junction portion may be spaced apart from an upper side of the uncoated portion.
[36]
The jelly roll electrode assembly may be wound in a circular shape on a plane.
Effects of the Invention
[37]
According to embodiments of the present invention, it is possible to prevent asymmetry or distortion of the shape of the electrode assembly from occurring when the electrode assembly is wound through the junction of the electrode tab wound 3/4 times or more and 1 time or less.
[38]
In addition, since the electrode tab is bonded to the uncoated region in a large area, it is easy to discharge heat generated from the electrode tab to the outside.
Brief description of the drawing
[39]
1 is an exploded perspective view showing a conventional jelly roll electrode assembly before it is wound.
[40]
FIG. 2 is a perspective view showing a state in which the electrode assembly of FIG. 1 is wound.
[41]
3 is an exploded perspective view illustrating an electrode assembly according to an embodiment of the present invention before being wound.
[42]
4 is a partial view showing an enlarged portion "A" of FIG.
[43]
5 is a view viewed from the opposite direction of the X-axis with respect to the electrode assembly of FIG.
[44]
6 is a view showing a state in which the electrode assembly of FIG. 5 is wound in the E direction.
[45]
7 is a view showing an electrode assembly having a stepped portion and a protruding portion.
[46]
8 is a view showing an electrode assembly having a recessed groove and a recessed groove insertion part.
[47]
9 is a partial view of an electrode assembly having a trimming part.
Modes for carrying out the invention
[48]
Hereinafter, with reference to the accompanying drawings, various embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. The present invention may be embodied in several different forms and is not limited to the embodiments described herein.
[49]
In order to clearly explain the present invention, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar elements throughout the specification.
[50]
In addition, since the size and thickness of each component shown in the drawings are arbitrarily indicated for convenience of description, the present invention is not necessarily limited to the illustrated bar. In order to clearly express various layers and regions in the drawings, the thicknesses are enlarged. And in the drawings, for convenience of description, the thickness of some layers and regions is exaggerated.
[51]
Also, when a part of a layer, film, region, plate, etc. is said to be “on” or “on” another part, this includes not only cases where it is “directly on” another part, but also cases where another part is in between. . Conversely, when we say that a part is "just above" another part, we mean that there is no other part in the middle. In addition, to be "on" or "on" the reference part means to be located above or below the reference part, and to necessarily mean to be located "on" or "on" in the direction opposite to gravity not.
[52]
In addition, throughout the specification, when a part "includes" a certain component, this means that other components may be further included, rather than excluding other components, unless otherwise stated.
[53]
In addition, throughout the specification, when referring to "planar", it means when the target part is viewed from above, and "in cross-section" means when viewed from the side when a cross-section of the target part is vertically cut.
[54]
3 is an exploded perspective view showing a state before the jelly roll electrode assembly 100 is wound according to an embodiment of the present invention.
[55]
Referring to FIG. 3 , a secondary battery according to an embodiment of the present invention includes a first electrode sheet 200 , a second electrode sheet 300 , and between the first electrode sheet 200 and the second electrode sheet 300 . The separator 400 interposed therein includes a jelly roll electrode assembly 100 wound together.
[56]
The active material layer 220 is formed on the first electrode sheet 200 , and the first electrode tab 210 may be bonded to the uncoated region 230 in which the active material layer 220 is not formed by welding or the like.
[57]
Similarly, the active material layer 320 is formed on the second electrode sheet 300 , and the second electrode tab 310 may be bonded to the uncoated region 330 in which the active material layer 320 is not formed by welding or the like. there is.
[58]
The first electrode sheet 200 and the second electrode sheet 300 may each correspond to one of the positive electrode sheet and the negative electrode sheet, and accordingly, the first electrode tab 210 and the second electrode tab 310 are the positive electrode sheets. It may correspond to one of a tab and a negative electrode tab, respectively.
[59]
The following will be described with reference to the first electrode tab 210 . In this case, the second electrode tab 310 may have a configuration of a conventional electrode tab unlike the first electrode tab 210 as shown in FIG. 3 . Alternatively, the second electrode tab in the present embodiment may have the same or similar configuration to the first electrode tab 210 .
[60]
4 is a partial view showing an enlarged portion "A" of FIG.
[61]
Referring to FIG. 4 , the first electrode tab 210 includes a junction portion 211 bonded to the uncoated region 230 and an extension portion 212 extending outwardly from the junction portion 211 .
[62]
The width C of the joint portion 211 is wider than the width D of the extension portion 212 . In FIG. 4 , the extension part 212 extends from the center of the upper side of the joint part 211 , but if the width C of the joint part 211 is wider than the width D of the extension part 212 , the extension part 212 . Since there is no limitation on the position of , the extension 212 may extend from any one end of the upper side of the junction 211 .
[63]
The reason that the width C of the junction 211 in this embodiment is wide is that when the first electrode sheet 200 including the junction 211 is wound, the junction 211 is 3/4 from the center of the electrode assembly. This is to ensure that it is wound more than once and not more than once. Hereinafter, it will be described in detail.
[64]
5 is a front view of the jelly roll electrode assembly 100 of FIG. 3 viewed from the opposite direction of the X axis.
[65]
Referring to FIG. 5 , in winding the first electrode sheet 200 , the second electrode sheet 300 , and the separator 400 , the first electrode tab 210 is formed based on the first electrode sheet 200 . It may be wound in the location direction (Z-axis direction), that is, in the E direction.
[66]
6 is a view showing a state in which the jelly roll electrode assembly of FIG. 5 is wound in the E direction.
[67]
Referring to FIG. 6 , the bonding portion 211 is wound at least 3/4 times and not more than once in the center of the jelly roll electrode assembly 100 , and more preferably, may be wound once.
[68]
As described above, in this embodiment, the width C of the junction 211 is widened as shown in FIG. 4 so that the junction 211 is wound at least 3/4 times and not more than once, unlike the conventional jelly roll electrode assembly. A symmetrical shape can be maintained. That is, the jelly roll electrode assembly 100 may be wound in a circular shape when viewed on a plane, that is, from above.
[69]
Therefore, consistent results can be obtained regardless of the positions of the electrode tabs 210 and 310 even when the secondary battery housing the jelly roll electrode assembly 100 is subjected to an impact test, and during the impact process, the jelly roll electrode assembly The problem of (100) being pushed can be solved.
[70]
In addition, even when the jelly roll electrode assembly 100 is charged and discharged, the problem that the shape is distorted can be minimized.
[71]
When the bonding portion 211 is wound less than 3/4 times, it is impossible to effectively prevent the wound jelly roll electrode assembly 100 from being asymmetric or from being distorted. On the other hand, when the bonding portion 211 is wound more than once, overlapping portions of the bonding portion 211 may occur, which may rather cause an asymmetrical shape of the jelly roll electrode assembly 100 , which is not preferable.
[72]
In addition, in the case of the electrode tab, excessive heat is generated, and the junction 211 bonded over a large area facilitates discharging the heat generated by the first electrode tab 210 to the outside. That is, the heat dissipation performance of the first electrode tab 210 may be improved through the bonding portion 211 bonded to a large area.
[73]
On the other hand, as shown in FIGS. 3 to 5 , the first electrode tab 210 including the bonding part 211 may be positioned at the center of the jelly roll electrode assembly 100 , and the first electrode sheet 200 is uncoated. The part 230 may be formed at one end of the first electrode sheet 200 .
[74]
On the other hand, in order to implement the symmetrical shape of the jelly roll electrode assembly 100, it is preferable that the bonding portion 211 is wound once. For this purpose, referring to FIGS. 4 and 6 together, one end 211a and the other end 211b of the bonding portion 211 may be in contact with each other. Also, as mentioned above, the first electrode sheet 200 may be wound in the E direction of FIG. 5 in order to bring the one end 211a and the other end 211b into contact with each other.
[75]
7 is a view showing an electrode assembly having a stepped portion 500 and a protruding portion 600 as a modified embodiment of the present invention, as viewed from the same direction as in FIG. 6 .
[76]
Referring to FIG. 7 , a stepped portion 500 may be formed at one end 211a-1 of the junction portion 211-1, and a stepped portion 500 may be formed at the other end 211b-1 of the junction portion 211-1. A protrusion 600 engaged with the 500 may be formed.
[77]
The stepped portion 500 and the protrusion 600 are configured to more easily implement one-time winding of the joint portion 211-1, and the protrusion 600 is fitted to the step formed by the step portion 500, One-time winding of the joint portion 211-1 can be effectively achieved. That is, it is possible to prevent the overlapping portion from being wound more than once through the step portion 500 and the protrusion portion 600 , the joint portion 211-1 being wound more than once.
[78]
In addition, since there is no limitation on the position of the protrusion 600 engaged with the step 500, the protrusion is formed at one end 211a-1 and the step portion is formed at the other end 211b-1, unlike FIG. 7 . can also
[79]
8 is a view showing an electrode assembly having a recessed groove 700 and a recessed groove insertion part 800 as a modified embodiment of the present invention, as viewed from the same direction as FIG. 6 .
[80]
Referring to FIG. 8 , an indentation groove 700 may be formed at one end 211a-2 of the junction portion 211-2, and an indentation groove 700 at the other end 211b-2 of the junction portion 211-2 ( An indentation groove insert 800 that can be inserted into the 700 may be formed.
[81]
The indentation groove 700 and the indentation groove insertion part 800 are configured to more easily implement one-time winding of the junction part 211-2, and the indentation groove insertion part 800 is inserted into the indentation groove 700, , it is possible to effectively achieve one-time winding of the joint 211-2. That is, it is possible to prevent the overlapping portion from being wound more than once through the indentation groove 700 and the indentation groove insertion portion 800 , the bonding portion 211-2.
[82]
In more detail, the indentation groove 700 and the indentation groove insertion part 800 may be located in the center of one end 211a-2 and the other end 211b-2, respectively. In other words, both the indentation groove 700 and the indentation groove insertion part 800 may be positioned to be spaced apart from the surface to which the joint part 211 - 2 is joined to the uncoated part and the surface opposite thereto.
[83]
By inserting the indentation groove insertion part 800 into the indentation groove 700 , a more robust coupling between the one end 211a-2 and the other end 211b-2 is possible.
[84]
In addition, since there is no limitation on the positions of the indentation groove 700 and the indentation groove insertion part 800, the indentation groove insertion part is formed at one end 211a-2, unlike FIG. A groove may be formed.
[85]
Meanwhile, referring to FIG. 4 , the extension 212 of the first electrode tab 210 extends in the direction of the upper side 231 of the uncoated area 230 , and the junction 211 is the upper side of the uncoated area 230 . (231) may be spaced apart. Although there is no particular limitation on the spaced distance (B), it is preferable that it is 2.0 mm or more and 3.0 mm or less.
[86]
If the bonding portion 211 is not spaced apart from the upper side 231 of the uncoated region 230 or the distance B is less than 2.0 mm, in the first electrode sheet to be wound, the first electrode tab 210 is formed of jelly. It can rise above the roll electrode assembly, and accordingly, the junction part 211 having a wide width C is exposed to the outside of the jelly roll electrode assembly, thereby rapidly increasing the possibility of problems such as short circuit.
[87]
9 is a partial view of an electrode assembly having a trimming part 900 .
[88]
Referring to FIG. 9 , the bonding portion 211-3 may include a trimming portion 900 formed on at least one of the corners of the bonding portion 211-3 bonded to the uncoated area 230 .
[89]
As in the present embodiment, by forming the trimming portion 900 , it is possible to prevent the electrode sheet or the separator from being torn due to the edges of the bonding portion 211-3 during winding.
[90]
Meanwhile, the secondary battery according to the embodiments of the present invention may include a battery case for accommodating the jelly roll electrode assembly. The battery case may be a cylindrical case, a prismatic case, or a pouch-type case, but is preferably a cylindrical case.
[91]
One or more secondary batteries according to the present embodiment described above may be applied to various devices. Such a device may be applied to a transportation means such as an electric bicycle, an electric vehicle, or a hybrid, but is not limited thereto, and may be applied to various devices capable of using a secondary battery.
[92]
Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the
[93]
Explanation of symbols
[94]
100: electrode assembly
[95]
200: first electrode sheet
[96]
210: first electrode tab
[97]
211: junction
[98]
212: extension
[99]
300: second electrode sheet
[100]
400: separator
[101]
500: step part
[102]
600: protrusion
[103]
700: indentation groove
[104]
800: indentation groove insertion part
[105]
Claims
[Claim 1]
a jelly roll electrode assembly in which a first electrode sheet, a second electrode sheet, and a separator interposed between the first electrode sheet and the second electrode sheet are wound together; and a first electrode tab bonded to the uncoated portion of the first electrode sheet and positioned at a central portion of the jelly roll electrode assembly, wherein the first electrode tab includes a joint portion bonded to the uncoated portion and an external portion from the joint portion. A secondary battery comprising an extended extension, wherein a width of the junction is wider than a width of the extension, and the junction is wound at least 3/4 times and not more than once in the center of the jelly roll electrode assembly.
[Claim 2]
The secondary battery of claim 1 , wherein the uncoated portion of the first electrode sheet is formed at one end of the first electrode sheet.
[Claim 3]
The secondary battery of claim 1 , wherein the first electrode sheet is wound in a direction in which the first electrode tab is positioned.
[Claim 4]
The secondary battery of claim 1 , wherein the junction part is wound once.
[Claim 5]
The secondary battery of claim 1 , wherein one end of the junction part is in contact with the other end opposite to the one end.
[Claim 6]
The secondary battery of claim 5 , wherein a step portion is formed at the one end of the junction portion, and a protrusion portion engaged with the step portion is formed at the other end of the junction portion.
[Claim 7]
The rechargeable battery of claim 5 , wherein a recessed groove is formed at the one end of the junction part, and an indentation groove insertion part inserted into the indentation groove is formed at the other end of the junction part.
[Claim 8]
The rechargeable battery of claim 7 , wherein the indentation groove and the indentation groove insertion part are spaced apart from a surface to which the joint part is joined to the uncoated part and a surface opposite to the surface to which the joint part is joined to the uncoated part.
[Claim 9]
The secondary battery of claim 1 , wherein the junction part includes a trimming part formed on at least one of corners of the junction part.
[Claim 10]
The rechargeable battery of claim 1 , wherein the extension portion extends in a direction of an upper side of the uncoated portion, and the junction portion is spaced apart from an upper side of the uncoated portion.
[Claim 11]
The secondary battery of claim 1, wherein the jelly roll electrode assembly is wound in a circular shape on a plane.
[Claim 12]
A device comprising at least one secondary battery according to claim 1 .