Cathode sheet and electrode assembly having the same

Abstract

The present application provides a cathode sheet, the cathode sheet including a first winding end and a second winding end along the length direction. The cathode sheet also includes a cathode current collector and a first cathode active layer. The first cathode active layer is arranged on the surface of the cathode current collector, the first cathode active layer includes a first end portion located at the first winding end, and a first cutout or a first barrier layer is arranged at the corner of the first end portion. The present application also provides an electrode assembly having the cathode sheet.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a cathode sheet and an electrode assembly having the cathode sheet. Background Art

[0002] Lithium-ion batteries have the advantages of high specific energy, high operating voltage, low self-discharge rate, small size and light weight, and are widely used in the field of consumer electronics. However, with the rapid development of electric vehicles and mobile electronic devices, people are paying more and more attention to and requiring more battery safety.

[0003] As we all know, the anode sheet usually includes a current collector (such as aluminum foil) and an active material layer coated on the surface of the current collector, and the active material layer is usually prepared by a gap coating process. Due to the mutual misalignment between the ends of the current collector and the active material layer, the slurry of the active material layer will shrink and form a missing corner during the curing process, resulting in the risk of lithium deposition in the anode sheet and causing battery capacity decay. Summary of the invention

[0004] In view of the above, it is necessary to propose a cathode sheet that can avoid lithium plating, so as to solve the above problems.

[0005] In addition, it is also necessary to provide an electrode assembly having the cathode sheet.

[0006] A preferred embodiment of the present application provides a cathode sheet, wherein the cathode sheet includes a first winding end and a second winding end along the length direction. The cathode sheet also includes: a cathode current collector; and a first cathode active layer, which is disposed on the surface of the cathode current collector. The first cathode active layer includes a first end portion located at the first winding end, and a first cutout or a first barrier layer is disposed at a corner of the first end portion.

[0007] Optionally, the first cathode active layer further includes a second end portion located at the second winding end, and a second cutout or a second barrier layer is provided at a corner of the second end portion.

[0008] Optionally, the cathode sheet further includes a second cathode active layer, and the cathode current collector is disposed between the first cathode active layer and the second cathode active layer. The second cathode active layer includes a third end portion located at the first winding end and a fourth end portion located at the second winding end, a third cutout or a third barrier layer is provided at a corner of the third end portion, and / or a fourth cutout or a fourth barrier layer is provided at a corner of the fourth end portion.

[0009] Optionally, one end of the cathode current collector extends beyond the first end and the third end to form a first blank area at the first winding end.

[0010] Optionally, the first end portion is offset from the third end portion to form a first single-sided region on the cathode current collector.

[0011] Optionally, the first end is flush with the third end to form a first double-sided region on the cathode current collector.

[0012] Optionally, the other end of the cathode current collector extends beyond the second end and the fourth end to form a second blank area at the second winding end.

[0013] Optionally, the second end is offset from the fourth end to form a second single-sided region on the cathode current collector, or the second end is flush with the fourth end to form a second double-sided region on the cathode current collector.

[0014] Optionally, the cathode sheet further comprises a plurality of tabs, wherein the tabs are arranged at the edge of the cathode current collector, and the edge of the cathode current collector provided with the tabs extends out of the first cathode active layer to form an extension portion, and an insulating layer is arranged on the extension portion.

[0015] The present application also provides an electrode assembly, comprising an anode sheet, the electrode assembly further comprising the cathode sheet as described above, the electrode assembly being formed by winding the anode sheet and the cathode sheet. The anode sheet comprises an anode current collector and an anode active layer disposed on the surface of the anode current collector, and the corners of the ends of the anode active layer comprise notches. The first incision or the first barrier layer corresponds to the notch.

[0016] The present application provides a first incision or a first barrier layer at the first end of the first cathode active layer, so that even if a notch is formed at the first end of the first anode active layer, lithium deposition at the corners of the first end of the first anode active layer can be avoided, thereby improving energy density. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1A This is a schematic diagram of the structure of the cathode sheet provided in Example 1 of the present application (including a top view, a front view and a bottom view).

[0018] Figure 1B This is a schematic diagram of the structure of the anode sheet provided in Example 1 of the present application (including a top view, a front view and a bottom view).

[0019] Figure 1C It is a top view of an electrode assembly formed by winding the cathode sheet shown in FIG. 1 and the anode sheet shown in FIG. 2 .

[0020] Figure 2A This is a schematic diagram of the structure of the cathode sheet provided in Example 2 of the present application.

[0021] Figure 2B This is a schematic diagram of the structure of the anode sheet provided in Example 2 of the present application.

[0022] Figure 3A This is a schematic diagram of the structure of the cathode sheet provided in Example 3 of the present application.

[0023] Figure 3B This is a schematic diagram of the structure of the anode sheet provided in Example 3 of the present application.

[0024] Figure 4A This is a schematic diagram of the structure of the cathode sheet provided in Example 4 of the present application.

[0025] Figure 4B This is a schematic diagram of the structure of the anode sheet provided in Example 4 of the present application.

[0026] Figure 5A This is a schematic diagram of the structure of the cathode sheet provided in Example 5 of the present application.

[0027] Figure 5B This is a schematic diagram of the structure of the anode sheet provided in Example 5 of the present application.

[0028] Fig. 6A This is a schematic diagram of the structure of the cathode sheet provided in Example 6 of the present application.

[0029] Figure 6B This is a schematic diagram of the structure of the anode sheet provided in Example 6 of the present application.

[0030] Explanation of symbols

[0031] Cathode current collector 11

[0032] The first cathode active layer 12

[0033] The second cathode active layer 13

[0034] Tab 14

[0035] Anode current collector 21

[0036] First anode active layer 22

[0037] Second anode active layer 23

[0038] Cathode sheet 100-105

[0039] First winding end 100a, 200a

[0040] Second winding end 100b, 200b

[0041] Extension 111

[0042] First insulating layer 112

[0043] First end 121, 221

[0044] First incision 122

[0045] Second end 123, 223

[0046] Second incision 124

[0047] First blank area 125

[0048] First single-sided area 126

[0049] First double-sided area 127

[0050] Second blank area 128

[0051] Second single-sided area 129

[0052] The second double-sided area 130

[0053] The third end 131, 231

[0054] The third incision 132

[0055] Fourth end 133, 233

[0056] Fourth incision 134

[0057] Anode sheet 200-205

[0058] First Gap 222

[0059] Second gap 224

[0060] Anode blank area 225, 228

[0061] Anode double-sided area 227

[0062] Anode single-sided area 229

[0063] Second insulating layer 230

[0064] Electrode assembly 400

[0065] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0066] Example 1

[0067] See also Figure 1A, an embodiment of the present application provides a cathode sheet 100, wherein the cathode sheet 100 includes a first winding end 100a and a second winding end 100b along the length direction. The cathode sheet 100 also includes a cathode current collector 11 and a first cathode active layer 12, wherein the first cathode active layer 12 is disposed on the surface of the cathode current collector 11. The first cathode active layer 12 includes a first end 121 located at the first winding end 100a, and a first incision 122 is provided at the corner of the first end 121. The first incision 122 may be a triangle, a square or other shapes. For example, the first incision 122 is approximately an isosceles right triangle, and the length of the right angle side is less than 10 mm. For another example, the shape of the hypotenuse of the first incision 122 may also be changed to an arc shape accordingly.

[0068] In another embodiment, the first cutout 122 may also be replaced by a first barrier layer (not shown) disposed at the corner of the first end portion 121. The first barrier layer may be an adhesive layer.

[0069] Please refer to Figure 1B and Figure 1C , the embodiment of the present application also provides an electrode assembly 400, including an anode sheet 200 and the cathode sheet 100. More specifically, the electrode assembly 400 may also include a separator 300 disposed between the anode sheet 200 and the cathode sheet 100. The electrode assembly 400 is formed by winding the anode sheet 200, the separator 300 and the cathode sheet 100. The anode sheet 200 includes a first winding end 200a and a second winding end 200b along the length direction. The anode sheet 200 also includes an anode current collector 21 and a first anode active layer 22 and a second anode active layer 23 disposed on the surface of the anode current collector 21, and the anode current collector 21 is located between the first anode active layer 22 and the second anode active layer 23. The first anode active layer 22 includes a first end 221 located at the first winding end 200a and a second end 223 located at the second winding end 200b. The second anode active layer 23 includes a third end 231 located at the first winding end 200a and a fourth end 233 located at the second winding end 200b. The first anode active layer 22 is formed on the anode current collector 21 by a gap coating process, resulting in the first end 221, the second end 223, the third end 231 and / or the fourth end 233 being misaligned with one end of the anode current collector 21 after cutting, so that a gap is generated at the first end 221, the second end 223, the third end 231 and / or the fourth end 233 when the slurry shrinks.

[0070] In the present embodiment, when the first end portion 221 of the first anode active layer 22 includes a first notch 222 at a corner, after the anode sheet 200 and the cathode sheet 100 are wound with the first winding ends 100a and 200a as the winding starting ends and the second winding ends 100b and 200b as the winding ending ends, the first cathode active layer 12 corresponds to the first anode active layer 22, and the first incision 122 or the first barrier layer corresponds to the first notch 222.

[0071] In this way, by providing a first incision 122 or a first barrier layer at the first end 121 of the first cathode active layer 12, even if a first notch 222 is formed at the first end 221 of the first anode active layer 22, lithium deposition at the corners of the first end 221 of the first anode active layer 22 can be avoided, thereby improving energy density.

[0072] In this embodiment, the first cathode active layer 10 further includes a second end 123 located at the second winding end 100b, and a second cutout 124 or a second barrier layer (not shown) is provided at the corner of the second end 123. The second cutout 124 and the second barrier layer may be in a triangular, square or other shape. The second barrier layer may be an adhesive layer.

[0073] When the second end 223 of the first anode active layer 22 includes a second notch 224 at a corner, after the anode sheet 200 and the cathode sheet 100 are wound, the second cutout 124 or the second barrier layer corresponds to the second notch 224 .

[0074] In this way, by providing a second incision 124 or a second barrier layer at the second end 123 of the first cathode active layer 12, even if a second notch 224 is formed at the second end 223 of the first anode active layer 22, lithium deposition at the corners of the second end 223 of the first anode active layer 22 can be avoided, thereby improving energy density.

[0075] In this embodiment, the cathode sheet 100 further includes a second cathode active layer 13, the cathode current collector 11 is disposed between the first cathode active layer 12 and the second cathode active layer 13, the second cathode active layer 13 includes a third end 131 located at the first winding end 100a and a fourth end 133 located at the second winding end 100b, the third end 131 is provided with a third cut 132 or a third barrier layer (not shown) at the corner, and / or the fourth end 133 is provided with a fourth cut 134 or a fourth barrier layer (not shown) at the corner. The third cut 132 and the third barrier layer may be in a triangular, square or other shape. The third barrier layer may be an adhesive layer. In an actual process, the first cut 122 and the third cut 132 may be formed in the same cutting step. The second cut 124 and the fourth cut 134 may be formed in the same cutting step.

[0076] In this embodiment, one end of the cathode current collector 11 extends out from the first end 121 and the third end 131 to form a first blank area 125 at the first winding end 100a, that is, the cathode current collector 11 is not coated with active material on both sides at the first winding end 100a. Further, the first end 121 is flush with the third end 131 to form a first double-sided area 127 on the cathode current collector 11.

[0077] The other end of the cathode current collector 11 extends out from the second end 123 and the fourth end 133 to form a second blank area 128 at the second winding end 100b. Further, the second end 123 and the fourth end 133 are offset to form a second single-sided area 129 on the cathode current collector 11.

[0078] Among them, the first winding end 200a and the second winding end 200b of the anode sheet 200 are also formed with an anode blank area 225 and an anode blank area 228, respectively. The anode sheet 200 is also provided with an anode single-sided area 229 and an anode double-sided area 227 in sequence adjacent to the anode blank area 225 and the anode blank area 228. After the anode sheet 200 and the cathode sheet 100 are wound, the anode blank area 225 of the anode sheet 200 is located at the innermost circle of the electrode assembly and is opposite to the first blank area 125 of the cathode sheet 100. The first double-sided area 127 and the second blank area 128 of the cathode sheet 100 are located at the outermost circle of the electrode assembly and the second blank area 128 is opposite to the anode blank area 228 of the anode sheet 200. The second blank area 128 and the anode blank area 228 together form a vest (MJ) structure. When abuse occurs, the second blank area 128 and the anode blank area 228 can quickly short-circuit or make a nail-through contact, thereby avoiding problems such as combustion or explosion, and improving the safety performance of the battery.

[0079] In this embodiment, the cathode sheet 100 further includes a plurality of tabs 14 (see Figure 1A ), the tab 14 is arranged at the edge of the cathode current collector 11, the edge of the cathode current collector 11 provided with the tab 14 extends out from the first cathode active layer 12 to form an extension portion 111, and a first insulating layer 112 is arranged on the extension portion 111. The first insulating layer 112 is used to prevent burrs from being generated on the cathode current collector 11 during the cutting process, thereby preventing the burrs from piercing the separator 300 and causing a short circuit.

[0080] Example 2

[0081] See also Figure 2A The embodiment of the present invention further provides a cathode sheet 101. Different from the cathode sheet 100, the cathode sheet 101 does not have a first blank area 125 at the first winding end 100a, thereby reducing the amount of the first insulating layer 112 and improving the energy density.

[0082] The embodiment of the present invention further provides an electrode assembly (not shown), the electrode assembly comprising the cathode sheet 101 and the anode sheet 201 (see Figure 2B The structure of the anode sheet 201 is the same as that of the anode sheet 200 in Example 1.

[0083] Example 3

[0084] See also Figure 3AThe embodiment of the present invention further provides a cathode sheet 102. Different from the cathode sheet 100, the cathode sheet 102 does not form a first blank area 125 at the first winding end 100a, and does not form a second blank area 128 at the second winding end 100b, thereby further reducing the amount of the first insulating layer 112 and improving the energy density.

[0085] The embodiment of the present invention further provides an electrode assembly (not shown), the electrode assembly comprising the cathode sheet 102 and the anode sheet 202 (see Figure 3B The structure of the anode sheet 202 is the same as that of the anode sheet 200 in Example 1.

[0086] Example 4

[0087] See also Figure 4A The embodiment of the present invention further provides a cathode sheet 103. The structure of the cathode sheet 103 is the same as that of the cathode sheet 100 in the first embodiment.

[0088] The embodiment of the present invention further provides an electrode assembly (not shown), the electrode assembly comprising the cathode sheet 103 and the anode sheet 203 (see Figure 4B ) is wound. Different from the anode sheet 200, the anode sheet 203 does not form an anode blank area 225 at the first winding end 200a, and does not form an anode blank area 228 at the second winding end 200b. In this way, the energy density can be improved with the same active material.

[0089] Example 5

[0090] See also Figure 5A The embodiment of the present invention further provides a cathode sheet 104. Different from the cathode sheet 100, in the cathode sheet 104, the first end 121 and the third end 131 are offset to form a first single-sided area 126 at the first winding end 100a. The second end 123 and the fourth end 133 are flush to form a second double-sided area 130 at the second winding end 100b.

[0091] The embodiment of the present invention further provides an electrode assembly (not shown), the electrode assembly comprising the cathode sheet 104 and the anode sheet 204 (see Figure 5B) is wound. Different from the anode sheet 200, the anode single-sided area 229 and the anode double-sided area 227 in the anode sheet 204 are located oppositely, that is, the anode single-sided area 229 and the anode double-sided area 227 are respectively arranged adjacent to the anode blank area 228 and the anode blank area 225. At this time, the anode blank area 228 and the anode single-sided area 229 of the anode sheet 204 are located at the outermost circle of the electrode assembly, and the anode blank area 228 is opposite to the second blank area 128 of the cathode sheet 104. The first blank area 125 of the cathode sheet 104 is located at the innermost circle of the electrode assembly.

[0092] In this embodiment, the anode blank area 228 and the anode single-sided area 229 of the anode sheet 202 are both provided with an insulating layer 230 on the exposed surface of the anode current collector 21, and the insulating layer 230 is used to prevent the metal foil from contacting with the battery outer packaging film and causing a short circuit. The single-sided area foil can be prevented from breaking by increasing the winding radius of the anode single-sided area 229 of the anode sheet 202.

[0093] Example 6

[0094] See also Fig. 6A The embodiment of the present invention further provides a cathode sheet 105. Different from the cathode sheet 104 of Example 5, the cathode sheet 105 does not form a first blank area 125 at the first winding end 100a, and does not form a second blank area 128 at the second winding end 100b.

[0095] The embodiment of the present invention further provides an electrode assembly (not shown), the electrode assembly comprising the cathode sheet 105 and the anode sheet 205 (see Figure 6B ) is wound. Different from the anode sheet 204 of Example 5, the anode sheet 205 does not have an anode blank area 225 formed at the first winding end 200a, and does not have an anode blank area 228 formed at the second winding end 200b.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the preferred embodiments, a person of ordinary skill in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application.

Claims

1. An electrode assembly, comprising a cathode sheet and an anode sheet, wherein the electrode assembly is formed by winding the anode sheet and the cathode sheet, wherein the cathode sheet comprises a first winding end and a second winding end along a length direction, and the anode sheet comprises a first winding end and a second winding end along the length direction, wherein: The cathode sheet also includes: cathode current collector; a first cathode active layer, disposed on the surface of the cathode current collector, the first cathode active layer comprising a first end portion located at the first winding end of the cathode sheet, a first cutout or a first barrier layer being disposed at a corner of the first end portion of the first cathode active layer, the first cutout penetrating the first cathode active layer along a thickness direction of the cathode sheet; and A plurality of tabs, wherein the tabs are arranged at the edge of the cathode current collector; along the width direction of the cathode sheet, the cathode tabs and the first cutout or the first barrier layer are located on the same side of the cathode sheet; The anode sheet also includes: an anode current collector; and A first anode active layer is arranged on the surface of the anode current collector, the first anode active layer includes a first end portion located at the first winding end of the anode sheet, the first end portion of the first anode active layer includes a first notch at a corner, a portion of the anode current collector is exposed in the first notch, the first incision or the first barrier layer corresponds to the first notch, the first barrier layer is an adhesive layer, and the first incision or the first barrier layer is used to avoid lithium deposition at the corner of the first end portion of the first anode active layer.

2. The electrode assembly according to claim 1, characterized in that The first cathode active layer further comprises a second end portion located at the second winding end of the cathode sheet, a second cutout or a second barrier layer is provided at a corner of the second end portion of the first cathode active layer, the second cutout penetrates the first cathode active layer along the thickness direction of the cathode sheet, and the second barrier layer is an adhesive layer; The first anode active layer also includes a second end portion located at the second winding end of the anode sheet, the second end portion of the first anode active layer includes a second notch at a corner, a portion of the anode current collector is exposed in the second notch, and the second incision or the second barrier layer corresponds to the second notch, so as to avoid lithium deposition at the corner of the second end portion of the first anode active layer.

3. The electrode assembly according to claim 2, characterized in that The cathode sheet further includes a second cathode active layer, the cathode current collector is disposed between the first cathode active layer and the second cathode active layer, and the second cathode active layer includes a third end portion located at the first winding end of the cathode sheet and a fourth end portion located at the second winding end of the cathode sheet; A third incision or a third barrier layer is provided at the corner of the third end, and the third incision penetrates the second cathode active layer along the thickness direction of the cathode sheet, and the third barrier layer is an adhesive layer, and / or a fourth incision or a fourth barrier layer is provided at the corner of the fourth end, and the fourth incision penetrates the second cathode active layer along the thickness direction of the cathode sheet.

4. The electrode assembly according to claim 3, characterized in that One end of the cathode current collector extends beyond the first end and the third end of the first cathode active layer to form a first blank area at the first winding end of the cathode sheet.

5. The electrode assembly according to claim 3, characterized in that: The first end and the third end of the first cathode active layer are offset to form a first single-sided region on the cathode current collector.

6. The electrode assembly according to claim 3, characterized in that The first end of the first cathode active layer is flush with the third end to form a first double-sided region on the cathode current collector.

7. The electrode assembly according to claim 4, characterized in that The other end of the cathode current collector extends beyond the second end and the fourth end of the first cathode active layer to form a second blank area at the second winding end of the cathode sheet.

8. The electrode assembly according to claim 3, characterized in that The second end of the first cathode active layer is offset from the fourth end to form a second single-sided region on the cathode current collector, or the second end of the first cathode active layer is flush with the fourth end to form a second double-sided region on the cathode current collector.

9. The electrode assembly according to claim 1, characterized in that: The edge of the cathode current collector provided with the electrode ear extends out of the first cathode active layer to form an extension portion, and an insulating layer is provided on the extension portion.

Images