Electrode components, batteries and electrical equipment

Abstract

An electrode assembly, a battery and an electrical device, wherein the electrode assembly comprises a first pole piece, a separator and a second pole piece arranged in sequence. The electrode assembly also comprises a pole lug, a first insulating layer and a second insulating layer. The first pole piece comprises a first current collector and a first active material layer coated on both sides of the first current collector. The first active material layer is provided with a pole lug groove, and a pole lug is provided in the pole lug groove. At least one surface of the first active material layer is provided with a thinning area connected to the pole lug groove, and the thinning area comprises a first recessed portion spaced apart from the pole lug groove in a first direction, and a second recessed portion arranged between the first recessed portion and the pole lug groove. The first insulating layer is arranged in the second recessed portion. The second insulating layer is connected to the side of the second pole piece facing the first recessed portion, and the projection of the second insulating layer in the first direction is located in the first recessed portion. The above-mentioned electrode assembly can improve the energy density of the electrode and reduce the risk of lithium plating.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to an electrode assembly, a battery and an electrical device. Background Art

[0002] In the existing battery structure, there are protruding adhesive tapes on both the tabs and the pole pieces. After winding, the overlapping adhesive tapes will affect the flatness of the battery. The intersection of the adhesive tapes and the active materials on the pole pieces is prone to lithium deposition during the charge and discharge process, affecting the battery cycle. At the same time, the protruding adhesive tapes will affect the energy density of the battery. Summary of the invention

[0003] In view of the above situation, it is necessary to provide an electrode assembly that can solve the above problems.

[0004] An embodiment of the present application provides an electrode assembly, which includes a first pole piece, a separator and a second pole piece arranged in sequence. The electrode assembly also includes a pole tab, a first insulating layer and a second insulating layer. The first pole piece includes a first current collector and a first active material layer coated on both sides of the first current collector in a first direction, and the first direction is the thickness direction of the first current collector. The first active material layer is provided with a pole tab groove exposing the first current collector, and a pole tab connected to the first current collector is provided in the pole tab groove. At least one surface of the first active material layer is provided with a thinning area connected to the pole tab groove, and the thinning area includes a first recessed portion spaced apart from the pole tab groove in the first direction, and a second recessed portion provided between the first recessed portion and the pole tab groove. The second direction is defined as the width direction of the first current collector. When viewed along the second direction, the bottom wall of the second recessed portion is separated by the pole tab groove to form two first step surfaces spaced apart, and the bottom wall of the first recessed portion is separated by the second recessed portion to form two second step surfaces spaced apart. The first insulating layer is provided in the second recessed portion, and the two ends of the first insulating layer are respectively located on the two first step surfaces. The second insulating layer is connected to the side of the second pole piece facing the first recessed portion, and the projection of the second insulating layer in the first direction is located in the first recessed portion. Along the first direction, the relationship between the depth T1 of the first recess, the depth T2 of the second recess, the thickness L1 of the first insulating layer and the thickness L2 of the second insulating layer satisfies: T1≤L2, T2≥L1, T1≤5μm, 5μm≤L2≤20μm.

[0005] In the above electrode assembly, the first insulating layer is accommodated by the second recess, and the first recess accommodates at least part of the second insulating layer, thereby improving the flatness of the electrode assembly, thereby improving the energy density of the battery provided with the electrode assembly. The thickness difference between the first active material layer located at both ends of the second insulating layer and the active material layer on the corresponding second pole piece is limited by the depth T1 of the first recess ≤ 5 μm, thereby reducing the risk of lithium deposition.

[0006] In some embodiments of the present application, 1 μm≤T1≤3 μm, so as to further limit the thickness difference between the first active material layer located at both ends of the second insulating layer and the active material layer on the corresponding second electrode sheet, thereby reducing the risk of lithium plating.

[0007] The embodiment of the present application also provides an electrode assembly, which includes a first pole piece, a separator and a second pole piece arranged in sequence. The electrode assembly also includes a pole ear, a first insulating layer and a second insulating layer. The first pole piece includes a first current collector and a first active material layer coated on both sides of the first current collector in a first direction, and the first direction is the thickness direction of the first current collector. The first active material layer is provided with a pole ear groove exposing the first current collector, and the pole ear connected to the first current collector is provided in the pole ear groove. At least one surface of the first active material layer is provided with a thinning area connected to the pole ear groove, and the thinning area includes a first recessed portion spaced apart from the pole ear groove in the first direction, and a second recessed portion provided between the first recessed portion and the pole ear groove. The second direction is defined as the width direction of the first current collector. When viewed along the second direction, the bottom wall of the second recessed portion is separated by the pole ear groove to form two first step surfaces spaced apart, and the bottom wall of the first recessed portion is separated by the second recessed portion to form two second step surfaces spaced apart. The first insulating layer is provided in the second recessed portion, and the two ends of the first insulating layer are respectively located on the two first step surfaces. The second insulating layer is connected to the side of the second electrode piece facing the first concave portion, and the projection of the second insulating layer in the first direction is located in the first concave portion. When viewed along the second direction, the first active material layer is further provided with flat coating areas located on both sides of the thinning area, and the electrode assembly further comprises two third insulating layers connected to both ends of the second insulating layer, and the projection of each third insulating layer in the first direction extends from the first concave portion to the flat coating area.

[0008] In the above electrode assembly, the first insulating layer is accommodated by the second recess, and the first recess accommodates at least part of the second insulating layer, thereby improving the flatness of the electrode assembly, thereby improving the energy density of the battery provided with the electrode assembly. The cathode impedance is increased by the third insulating layer to reduce the risk of lithium deposition due to the large thickness difference between the first active material layer at both ends of the second insulating layer and the active material layer on the corresponding second pole piece.

[0009] In some embodiments of the present application, along the first direction, the relationship between the depth T1 of the first recess, the depth T2 of the second recess, the thickness L1 of the first insulating layer, and the thickness L2 of the second insulating layer satisfies: T1≥L2, T2≥L1, T1>5μm, so that the second insulating layer is completely embedded in the middle of the first recess and the first insulating layer is completely contained in the second recess, so as to eliminate the influence of the second insulating layer and the first insulating layer on the flatness of the electrode assembly.

[0010] In some embodiments of the present application, the third insulating layer is formed by coating polyvinyl alcohol or polyacrylic acid or a mixture of the two on the second pole piece.

[0011] In some embodiments of the present application, along the first direction, the thickness L3 of the third insulating layer satisfies: 2 μm≤L3≤5 μm, so as to reduce the influence of the third insulating layer on the flatness of the electrode assembly while maintaining stable insulation performance.

[0012] In some embodiments of the present application, the third direction is defined as the length direction of the first current collector. Along the third direction, the length D3 of the third insulating layer satisfies: 4mm≤D3≤8mm, so that the projection of the third insulating layer in the first direction extends from the first recessed portion to the flat coating area.

[0013] In some embodiments of the present application, along the third direction, the relationship among the length W1 of the first recess, the length W2 of the second recess, the length D1 of the first insulating layer, and the length D2 of the second insulating layer satisfies: W1≥D2, W2≥D1, W1>W2, D2>D1, so that the second recess can accommodate the first insulating layer in the third direction, and the first recess can accommodate the second insulating layer in the third direction.

[0014] In some embodiments of the present application, the first active material layer includes a first surface and a second surface arranged opposite to each other in a first direction. The thinning area includes a first thinning area and a second thinning area, the first thinning area is arranged on the first surface, and the second thinning area is arranged on the second surface. Along the first direction, the projection of the first recess in the first thinning area overlaps with the projection of the first recess in the second thinning area, and the projection of the second recess in the first thinning area overlaps with the projection of the second recess in the second thinning area. The first thinning area and the second thinning area cooperate to reduce the influence of the first insulating layer and the second insulating layer on the flatness of the electrode assembly, thereby reducing the risk of lithium deposition.

[0015] In some embodiments of the present application, the first current collector in the tab groove is provided with a third recessed portion along the first direction, and the tab is accommodated in the third recessed portion. The third recessed portion is used to reduce the effect of the tab on the thickness of the first pole sheet 10 in the first direction.

[0016] In some embodiments of the present application, the first active material layer includes a first surface and a second surface arranged opposite to each other in a first direction. The first active material layer is provided with a thinning area, and the thinning area is provided on one of the first surface and the second surface. The electrode assembly also includes a fourth insulating layer and a fifth insulating layer, the fourth insulating layer is connected to the other of the first surface and the second surface, the fourth insulating layer covers the end of the pole ear groove away from the thinning area, and the fifth insulating layer is connected to the side of the second pole piece facing the fourth insulating layer. Along the first direction, the projection of the first insulating layer overlaps with the projection of the fourth insulating layer, and the projection of the second insulating layer overlaps with the projection of the fifth insulating layer.

[0017] In some embodiments of the present application, along the first direction, the relationship between the depth T1 of the first recess, the depth T2 of the second recess, the thickness L1 of the first insulating layer, the thickness L2 of the second insulating layer, the thickness L4 of the fourth insulating layer, and the thickness L5 of the fifth insulating layer satisfies: L1+L4≤T2, L2+L5≤T1. The first recess can eliminate the influence of the second insulating layer and the fifth insulating layer on the flatness of the electrode assembly, and the second recess can eliminate the influence of the first insulating layer and the fourth insulating layer on the flatness of the electrode assembly, thereby reducing the risk of lithium deposition.

[0018] An embodiment of the present application further provides a battery, comprising the electrode assembly in any of the above embodiments.

[0019] An embodiment of the present application further provides an electrical device, comprising the battery in any of the above embodiments.

[0020] In the battery and electrical equipment of the present application, the first insulating layer is accommodated by the second recess, and the first recess accommodates at least part of the second insulating layer, so as to improve the flatness of the electrode assembly, thereby improving the energy density of the battery provided with the electrode assembly. On the one hand, the thickness difference between the first active material layer at both ends of the second insulating layer and the corresponding active material layer on the second pole piece is limited by the depth T1≤5μm of the first recess, thereby reducing the risk of lithium deposition. On the other hand, the cathode impedance is increased by the third insulating layer to reduce the risk of lithium deposition due to the large thickness difference between the first active material layer at both ends of the second insulating layer and the corresponding active material layer on the second pole piece. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a first structural schematic diagram of an electrode assembly in one embodiment of the present application.

[0022] Figure 2 It is a schematic diagram of the dimensions of an electrode assembly in one embodiment of the present application.

[0023] Figure 3 It is a second structural schematic diagram of an electrode assembly in one embodiment of the present application.

[0024] Figure 4 This is a comparison chart of cyclic thickness expansion data of a battery in one embodiment of the present application.

[0025] Figure 5 It is a third structural schematic diagram of an electrode assembly in one embodiment of the present application.

[0026] Figure 6 It is a schematic diagram of the structure of a battery and an electrical device in one embodiment of the present application.

[0027] Main component symbols

[0028] Electrode assemblies 100, 100a, 100b, 100c

[0029] Battery 200

[0030] Electrical equipment 300

[0031] The first pole piece 10

[0032] The first current collector 11

[0033] Third recess 111

[0034] First active material layer 12

[0035] Thinning area 12a

[0036] first recess 121

[0037] Second step surface 121a

[0038] Second recess 122

[0039] First step surface 122a

[0040] First surface 123

[0041] Second surface 124

[0042] Flat coating area 12b

[0043] First thinned area 12c

[0044] Second thinned area 12d

[0045] Tab slot 13

[0046] Isolation film 20

[0047] Part 21

[0048] The second pole piece 30

[0049] Second fluid collector 31

[0050] The second active material layer 32

[0051] Tab 40

[0052] First insulating layer 51

[0053] Second insulating layer 52

[0054] The third insulating layer 53

[0055] Fourth insulating layer 54

[0056] Fifth insulating layer 55

[0057] First direction Z

[0058] Second direction X

[0059] The third direction Y

[0060] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0061] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0062] It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be a centrally disposed element at the same time. When an element is considered to be "disposed on" another element, it may be directly disposed on the other element or there may be a centrally disposed element at the same time.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0064] It should be understood that, considering the actual processing tolerance factors, in the technical solution of the present application, when the two elements are arranged parallel / vertically and in the same direction, there may be a certain angle between the two elements, and a tolerance of 0-±10% is allowed between the two elements. The tolerance of the two elements greater than, equal to or less than 0-±10% is allowed.

[0065] The embodiments of the present application are further described with reference to the accompanying drawings.

[0066] Please also read Figure 1 The embodiment of the present application provides an electrode assembly 100, which includes a first electrode sheet 10, a separator 20, and a second electrode sheet 30 arranged in sequence. Optionally, the first electrode sheet 10, the separator 20, and the second electrode sheet 30 are wound or stacked.

[0067] The electrode assembly 100 further includes a tab 40, a first insulating layer 51 and a second insulating layer 52. The first pole piece 10 includes a first current collector 11 and a first active material layer 12 coated on both sides of the first current collector 11 in a first direction Z, and the first direction Z is the thickness direction of the first current collector 11. The first active material layer 12 is provided with a tab groove 13 exposing the first current collector 11, and the tab groove 13 is provided with a tab 40 connected to the first current collector 11. The first active material layer 12 can allow lithium ions to be extracted and embedded. The first current collector 11 conducts the current generated by the electrochemical reaction to the external circuit through the tab 40, thereby realizing the process of converting chemical energy into electrical energy.

[0068] The second direction X is defined as the width direction of the first current collector 11, and the third direction Y is defined as the length direction of the first current collector 11. The length direction and the width direction of the first current collector 11 refer to two dimensions of the surface of the first current collector 11, respectively. The length direction refers to the main dimension direction (i.e., the direction of the larger size), and the width direction refers to the secondary dimension direction (i.e., the direction of the smaller size). Generally, the length direction is consistent with the coating direction of each material layer (e.g., the first active material layer 12) during the processing of the first pole piece 10, and is also consistent with the winding direction of the first pole piece 10, the isolation film 20, and the second pole piece 30. The width direction is perpendicular to the length direction.

[0069] At least one surface of the first active material layer 12 is provided with a thinned area 12a connected to the tab groove 13, and the thinned area 12a includes a first recess 121 spaced apart from the tab groove 13 in the first direction Z, and a second recess 122 disposed between the first recess 121 and the tab groove 13. When viewed along the second direction X, the bottom wall of the second recess 122 is divided by the tab groove 13 to form two spaced apart first step surfaces 122a, and the bottom wall of the first recess 121 is divided by the second recess 122 to form two spaced apart second step surfaces 121a.

[0070] The first insulating layer 51 is disposed in the second concave portion 122 , and two ends of the first insulating layer 51 are respectively located on the two first step surfaces 122 a . The first insulating layer 51 is used to separate the electrode tab 40 and the second electrode sheet 30 .

[0071] The second insulating layer 52 is connected to the side of the second pole piece 30 facing the first recess 121, and the projection of the second insulating layer 52 in the first direction Z is located in the first recess 121. The second insulating layer 52 is used to further separate the pole tab 40 and the second pole piece 30. Specifically, the isolation film 20 includes a first portion 21 adjacent to the second insulating layer 52, and along the first direction Z, the projection of the second insulating layer 52 overlaps with the projection of the first portion 21. In the first direction Z, at least part of the second insulating layer 52 is embedded in the first recess 121, and the first portion 21 is embedded in the first recess 121 driven by the second insulating layer 52, and the two ends of the projection of the second insulating layer 52 in the first direction Z are respectively located on the two second step surfaces 121a.

[0072] The first insulating layer 51 is accommodated by the second recess 122 , and the first recess 121 accommodates at least a portion of the second insulating layer 52 , thereby improving the flatness of the electrode assembly 100 and further improving the energy density of the battery provided with the electrode assembly 100 .

[0073] Please also read Figure 2 Along the third direction Y, the relationship between the length W1 of the first recess, the length W2 of the second recess, the length D1 of the first insulating layer and the length D2 of the second insulating layer satisfies: W1≥D2, W2≥D1, W1>W2, D2>D1, so that the second recess 122 can accommodate the first insulating layer 51 in the third direction Y, and the first recess 121 can accommodate the second insulating layer 52 in the third direction Y.

[0074] Please also read Figure 1 and Figure 2 , in some embodiments, along the first direction Z, the relationship between the depth T1 of the first recess 121, the depth T2 of the second recess 122, the thickness L1 of the first insulating layer 51, and the thickness L2 of the second insulating layer 52 satisfies: T1≤L2, T2≥L1, T1≤5μm, 5μm≤L2≤20μm. Specifically, in the first direction Z, the second insulating layer 52 is at least partially embedded in the first recess 121 to eliminate the influence of at least part of the second insulating layer 52 on the flatness of the electrode assembly 100. Optionally, when T1=L2, the second insulating layer 52 is completely embedded in the first recess 121; when T1<L2, the second insulating layer 52 is partially embedded in the first recess 121. The first insulating layer 51 is completely embedded in the second recess 122 to eliminate the influence of the first insulating layer 51 on the flatness of the electrode assembly 100. By limiting T1≤5 μm, the thickness difference between the first active material layer 12 located at both ends of the second insulating layer 52 and the corresponding active material layer on the second electrode 30 is limited, thereby reducing the risk of lithium deposition.

[0075] It can be understood that the second pole piece 30 includes a second current collector 31 and a second active material layer 32 coated on both sides of the second current collector 31. Along the first direction Z, the thickness of the second active material layer 32 is the same as the thickness of the first active material layer 12 where the thinning area 12a is not set.

[0076] Optionally, T1 may be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, and any other value within the range of T1 ≤ 5 μm.

[0077] Furthermore, 1 μm≤T1≤3 μm, so as to further limit the thickness difference between the first active material layer 12 located at both ends of the second insulating layer 52 and the corresponding active material layer on the second electrode 30 , thereby reducing the risk of lithium deposition.

[0078] Furthermore, T1 is 1 μm, so as to further limit the thickness difference between the first active material layer 12 located at both ends of the second insulating layer 52 and the corresponding active material layer on the second electrode 30 , thereby reducing the risk of lithium deposition.

[0079] Optionally, L2 may be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, or any other value within the range of 5 μm≤L2≤20 μm.

[0080] See also Figure 3 In some embodiments, along the first direction Z, the relationship between the depth T1 of the first recess 121, the depth T2 of the second recess 122, the thickness L1 of the first insulating layer 51, and the thickness L2 of the second insulating layer 52 satisfies: T1≥L2, T2≥L1, T1>5μm. Specifically, in the first direction Z, the second insulating layer 52 is completely embedded in the first recess 121 to eliminate the influence of the second insulating layer 52 on the flatness of the electrode assembly 100. The first insulating layer 51 is completely contained in the second recess 122 to eliminate the influence of the first insulating layer 51 on the flatness of the electrode assembly 100.

[0081] Observing along the second direction X, the first active material layer 12 is also provided with a flat coating area 12b located on both sides of the thinning area 12a. The electrode assembly 100 also includes two third insulating layers 53 connected to the two ends of the second insulating layer 52, and the projection of each third insulating layer 53 in the first direction Z extends from the first recess 121 to the flat coating area 12b. Specifically, each third insulating layer 53 extends from the end of the second insulating layer 52 to the outside of the first recess 121, and the third insulating layer 53 is used to separate the first active material layer 12 at both ends of the second insulating layer 52 and the corresponding active material layer on the second pole piece 30, so as to reduce the risk of lithium deposition due to the large difference in thickness between the first active material layer 12 at both ends of the second insulating layer 52 and the corresponding active material layer on the second pole piece 30.

[0082] It is understandable that when T1≤5 μm, two third insulating layers 53 may be provided at both ends of the second insulating layer 52 to further reduce the risk of lithium plating.

[0083] See also Figure 4 Optionally, the third insulating layer 53 is formed by coating polyvinyl alcohol (PVA) or polyacrylic acid (PAA) or a mixture of the two on the second electrode 30. After coating, the cathode impedance at the coating position can be increased, and the amount of lithium ions released at the corresponding position can be reduced, thereby reducing the risk of lithium deposition at the coating position.

[0084] In some embodiments, along the first direction Z, the thickness L3 of the third insulating layer 53 satisfies: 2 μm≤L3≤5 μm, so as to reduce the influence of the third insulating layer 53 on the flatness of the electrode assembly 100 while maintaining stable insulation performance.

[0085] Optionally, L3 may be 2 μm, 3 μm, 4 μm, 5 μm, and any other value in the range of 2 μm≤L3≤5 μm.

[0086] In some embodiments, along the third direction Y, the length D3 of the third insulating layer 53 satisfies: 4 mm≤D3≤8 mm, so that the projection of the third insulating layer 53 in the first direction Z extends from the first recess 121 to the flat coating area 12 b.

[0087] Optionally, L3 may be 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, and any other value within the range of 4 mm ≤ D3 ≤ 8 mm.

[0088] In some embodiments, the first active material layer 12 includes a first surface 123 and a second surface 124 disposed opposite to each other in the first direction Z, and the first surface 123 and the second surface 124 are respectively located on both sides of the first current collector 11. The skived region 12a includes a first skived region 12c and a second skived region 12d, the first skived region 12c is disposed on the first surface 123, and the second skived region 12d is disposed on the second surface 124.

[0089] The first thinning area 12c and the second thinning area 12d are respectively provided with a first recess 121 and a second recess 122. Along the first direction Z, the projection of the first recess 121 in the first thinning area 12c overlaps with the projection of the first recess 121 in the second thinning area 12d, and the projection of the second recess 122 in the first thinning area 12c overlaps with the projection of the second recess 122 in the second thinning area 12d. Correspondingly, the first thinning area 12c and the second thinning area 12d are respectively provided with a first insulating layer 51 and a second insulating layer 52, and the first thinning area 12c and the second thinning area 12d cooperate to reduce the influence of the first insulating layer 51 and the second insulating layer 52 on the flatness of the electrode assembly 100, thereby reducing the risk of lithium deposition.

[0090] It can be understood that the first thinned area 12c and the second thinned area 12d may be selectively provided with a third insulating layer 53 according to the depth T1 of each first concave portion 121. Specifically, when the depth T1 of the first concave portion 121 of both the first thinned area 12c and the second thinned area 12d is ≤5μm, the first thinned area 12c and the second thinned area 12d are not provided with the third insulating layer 53. When the depth T1 of the first concave portion 121 of both the first thinned area 12c and the second thinned area 12d is greater than 5μm, the first thinned area 12c and the second thinned area 12d are respectively provided with a third insulating layer 53, and the projections of the two third insulating layers 53 on one side of the tab 40 in the third direction Y in the first direction Z overlap. When the depth T1 of the first concave portion 121 of the first thinned region 12c is ≤5μm, and the depth T1 of the first concave portion 121 of the second thinned region 12d is >5μm, the first thinned region 12c is not provided with the third insulating layer 53, and the second thinned region 12d is provided with the third insulating layer 53. When the depth T1 of the first concave portion 121 of the first thinned region 12c is >5μm, and the depth T1 of the first concave portion 121 of the second thinned region 12d is ≤5μm, the first thinned region 12c is provided with the third insulating layer 53, and the second thinned region 12d is not provided with the third insulating layer 53.

[0091] See also Figure 5 In some embodiments, the first active material layer 12 is provided with a thinning region 12a, and the thinning region 12a is provided on one of the first surface 123 and the second surface 124. The electrode assembly 100 further includes a fourth insulating layer 54 and a fifth insulating layer 55, the fourth insulating layer 54 is connected to the other of the first surface 123 and the second surface 124, the fourth insulating layer 54 covers one end of the pole tab groove 13 away from the thinning region 12a, and the fifth insulating layer 55 is connected to the side of the second pole piece 30 facing the fourth insulating layer 54. The fourth insulating layer 54 and the fifth insulating layer 55 are used to separate the pole tab 40 and the second pole piece 30 on the side away from the thinning region 12a.

[0092] Along the first direction Z, the projection of the first insulating layer 51 overlaps with the projection of the fourth insulating layer 54 , and the projection of the second insulating layer 52 overlaps with the projection of the fifth insulating layer 55 , so that the insulation areas on both sides of the tab 40 are roughly the same, thereby improving the stability of insulation.

[0093] Along the first direction Z, the relationship among the depth T1 of the first recess 121, the depth T2 of the second recess 122, the thickness L1 of the first insulating layer 51, the thickness L2 of the second insulating layer 52, the thickness L4 of the fourth insulating layer 54, and the thickness L5 of the fifth insulating layer 55 satisfies: L1+L4≤T2, L2+L5≤T1. Specifically, in the first direction Z, the second insulating layer 52 is completely embedded in the first recess 121, the first insulating layer 51 is completely contained in the second recess 122, the fourth insulating layer 54 and the fifth insulating layer 55 can protrude toward the thinning area 12a, the first recess 121 can eliminate the influence of the second insulating layer 52 and the fifth insulating layer 55 on the flatness of the electrode assembly 100, and the second recess 122 can eliminate the influence of the first insulating layer 51 and the fourth insulating layer 54 on the flatness of the electrode assembly 100, thereby reducing the risk of lithium plating.

[0094] In some embodiments, the first current collector 11 in the tab groove 13 is provided with a third recess 111 sunken along the first direction Z, and the third recess 111 is used to reduce the influence of the tab 40 in the first direction Z on the thickness of the first pole sheet 10 .

[0095] See also Figure 6 , an embodiment of the present application further provides a battery 200, and the battery 200 includes the electrode assembly 100 in any of the above embodiments.

[0096] See also Figure 6 The embodiment of the present application also provides an electric device 300, which includes the battery 200 in any of the above embodiments. The electric device 300 can be an electronic device such as a mobile phone, a tablet computer, or a mobile device such as a drone or an electric car.

[0097] In summary, in the above-mentioned electrode assembly 100, battery 200 and electrical equipment 300, the first insulating layer 51 is accommodated by the second recess 122, and the first recess 121 accommodates at least part of the second insulating layer 52, thereby improving the flatness of the electrode assembly 100, and further improving the energy density of the battery provided with the electrode assembly 100. On the one hand, the thickness difference between the first active material layer 12 at both ends of the second insulating layer 52 and the corresponding active material layer on the second pole piece 30 is limited by the depth T1≤5μm of the first recess 121, thereby reducing the risk of lithium deposition. On the other hand, the cathode impedance is increased by the third insulating layer 53 to reduce the risk of lithium deposition due to the large thickness difference between the first active material layer 12 at both ends of the second insulating layer 52 and the corresponding active material layer on the second pole piece 30.

[0098] The following is a further detailed description of Examples 1-3 of the present application with reference to the accompanying drawings.

[0099] Embodiment 1

[0100] See also Figure 1 , Embodiment 1 of the present application provides an electrode assembly 100a, wherein the thinned area 12a includes a first thinned area 12c and a second thinned area 12d, wherein the first thinned area 12c is disposed on the first surface 123, and the second thinned area 12d is disposed on the second surface 124. The first thinned area 12c and the second thinned area 12d are respectively provided with a first recess 121 and a second recess 122. Along the first direction Z, the projection of the first recess 121 in the first thinned area 12c overlaps with the projection of the first recess 121 in the second thinned area 12d, and the projection of the second recess 122 in the first thinned area 12c overlaps with the projection of the second recess 122 in the second thinned area 12d. Correspondingly, the first thinned area 12c and the second thinned area 12d are respectively provided with a first insulating layer 51 and a second insulating layer 52. The depth T1 of the first concave portion 121 of both the first thinned region 12 c and the second thinned region 12 d is ≤5 μm, and the third insulating layer 53 is not provided in the first thinned region 12 c and the second thinned region 12 d .

[0101] Along the third direction Y, the length of the tab groove 13 is 9 mm, and the width of the tab 40 is 6 mm.

[0102] In the first thinning zone 12c, the length D1 of the first insulating layer 51 is 11 mm, the thickness L1 of the first insulating layer 51 is 16 μm, the length W2 of the second recess 122 is 13 mm, the depth T2 of the second recess 122 is 18 μm, the length D2 of the second insulating layer 52 is 20 mm, the thickness L2 of the second insulating layer 52 is 10 μm, the length W1 of the first recess 121 is 26 mm, and the depth T1 of the first recess 121 is 5 μm.

[0103] In the second thinning zone 12d, the length D1 of the first insulating layer 51 is 11 mm, the thickness L1 of the first insulating layer 51 is 16 μm, the length W2 of the second recess 122 is 13 mm, the depth T2 of the second recess 122 is 18 μm, the length D2 of the second insulating layer 52 is 20 mm, the thickness L2 of the second insulating layer 52 is 10 μm, the length W1 of the first recess 121 is 26 mm, and the depth T1 of the first recess 121 is 5 μm.

[0104] In the above-mentioned electrode assembly 100a, in the first direction Z, the second insulating layer 52 is embedded in the first recess 121 from outside the first recess 121 to eliminate the influence of part of the second insulating layer 52 on the flatness of the electrode assembly 100. The first insulating layer 51 is completely contained in the second recess 122 to eliminate the influence of the first insulating layer 51 on the flatness of the electrode assembly 100. The thickness difference between the first active material layer 12 located at both ends of the second insulating layer 52 and the corresponding active material layer on the second pole piece 30 is limited by T1≤5μm, thereby reducing the risk of lithium deposition.

[0105] Embodiment 2

[0106] See also Figure 4 , Embodiment 1 of the present application provides an electrode assembly 100b, wherein the thinned area 12a includes a first thinned area 12c and a second thinned area 12d, wherein the first thinned area 12c is disposed on the first surface 123, and the second thinned area 12d is disposed on the second surface 124. The first thinned area 12c and the second thinned area 12d are respectively provided with a first recess 121 and a second recess 122. Along the first direction Z, the projection of the first recess 121 in the first thinned area 12c overlaps with the projection of the first recess 121 in the second thinned area 12d, and the projection of the second recess 122 in the first thinned area 12c overlaps with the projection of the second recess 122 in the second thinned area 12d. Correspondingly, the first thinned area 12c and the second thinned area 12d are respectively provided with a first insulating layer 51 and a second insulating layer 52. The depth T1 of the first concave portion 121 of both the first thinned region 12 c and the second thinned region 12 d is greater than 5 μm, and the third insulating layer 53 is disposed in both the first thinned region 12 c and the second thinned region 12 d.

[0107] Along the third direction Y, the length of the tab groove 13 is 9 mm, and the width of the tab 40 is 6 mm.

[0108] In the first thinning zone 12c, the length D1 of the first insulating layer 51 is 11 mm, the thickness L1 of the first insulating layer 51 is 16 μm, the length W2 of the second recess 122 is 13 mm, the depth T2 of the second recess 122 is 18 μm, the length D2 of the second insulating layer 52 is 20 mm, the thickness L2 of the second insulating layer 52 is 10 μm, the length W1 of the first recess 121 is 26 mm, and the depth T1 of the first recess 121 is 12 μm. In the second thinning area 12d, the third insulating layer 53 has a length D1 of the first insulating layer 51 of 11 mm, a thickness L1 of the first insulating layer 51 of 16 μm, a length W2 of the second recess 122 of 13 mm, a depth T2 of the second recess 122 of 18 μm, a length D2 of the second insulating layer 52 of 20 mm, a thickness L2 of the second insulating layer 52 of 10 μm, a length W1 of the first recess 121 of 26 mm, and a depth T1 of the first recess 121 of 12 μm.

[0109] The thickness L3 of the third insulating layer 53 satisfies: 2 μm≤L3≤5 μm, and the length D3 of the third insulating layer 53 satisfies: 4 mm≤D3≤8 mm.

[0110] In the above-mentioned electrode assembly 100b, in the first direction Z, the second insulating layer 52 is completely embedded in the first recess 121 to eliminate the influence of the second insulating layer 52 on the flatness of the electrode assembly 100. The first insulating layer 51 is completely contained in the second recess 122 to eliminate the influence of the first insulating layer 51 on the flatness of the electrode assembly 100. The cathode impedance is increased by the third insulating layer 53 to reduce the risk of lithium deposition due to the large thickness difference between the first active material layer 12 at both ends of the second insulating layer 52 and the corresponding active material layer on the second pole piece 30.

[0111] Embodiment 3

[0112] See also Figure 5 , Embodiment 1 of the present application provides an electrode assembly 100c, wherein the first active material layer 12 is provided with a thinning region 12a, and the thinning region 12a is provided on the first surface 123. The first thinning region 12c is provided with a first recess 121 and a second recess 122. Correspondingly, the first thinning region 12c and the second thinning region 12d are provided with a first insulating layer 51 and a second insulating layer 52, respectively. The electrode assembly 100 also includes a fourth insulating layer 54 and a fifth insulating layer 55,

[0113] The fourth insulating layer 54 is connected to the second surface 124 and covers one end of the electrode tab groove 13 away from the thinned region 12 a . The fifth insulating layer 55 is connected to a side of the second electrode piece facing the fourth insulating layer 54 .

[0114] Along the third direction Y, the length of the tab groove 13 is 9 mm, and the width of the tab 40 is 6 mm.

[0115] In the thinning area 12a, the length D1 of the first insulating layer 51 is 11 mm, the thickness L1 of the first insulating layer 51 is 16 μm, the length W2 of the second recess 122 is 13 mm, the depth T2 of the second recess 122 is 36 μm, the length D2 of the second insulating layer 52 is 20 mm, the thickness L2 of the second insulating layer 52 is 10 μm, the length W1 of the first recess 121 is 26 mm, and the depth T1 of the first recess 121 is 24 μm.

[0116] Along the third direction Y, the length of the fourth insulating layer 54 is 11 mm, the length of the fifth insulating layer 55 is 20 mm, and along the first direction Z, the thickness L4 of the fourth insulating layer 54 is 16 mm, and the thickness L5 of the fifth insulating layer 55 is 10 mm.

[0117] In the above-mentioned electrode assembly 100b, in the first direction Z, the second insulating layer 52 is completely embedded in the first recess 121, the first insulating layer 51 is completely contained in the second recess 122, the fourth insulating layer 54 and the fifth insulating layer 55 can protrude toward the thinned area 12a, the first recess 121 can eliminate the influence of the second insulating layer 52 and the fifth insulating layer 55 on the flatness of the electrode assembly 100, and the second recess 122 can eliminate the influence of the first insulating layer 51 and the fourth insulating layer 54 on the flatness of the electrode assembly 100. The cathode impedance is increased by the third insulating layer 53 to reduce the risk of lithium deposition due to the large thickness difference between the first active material layer 12 at both ends of the second insulating layer 52 and the corresponding active material layer on the second pole piece 30.

[0118] In addition, those skilled in the art may also make other changes within the spirit of the present application. Of course, these changes made according to the spirit of the present application should be included in the scope disclosed in the present application.

Claims

1. An electrode assembly, comprising a first pole piece, a separator and a second pole piece arranged in sequence, the electrode assembly further comprising a pole ear, a first insulating layer and a second insulating layer, the first pole piece comprising a first current collector and a first active material layer coated on both sides of the first current collector in a first direction, the first direction being the thickness direction of the first current collector, the first active material layer being provided with a pole ear groove exposing the first current collector, the pole ear groove being provided with a pole ear connected to the first current collector, characterized in that: The first active material layer includes a first surface and a second surface arranged opposite to each other in the first direction, the first surface and the second surface are away from the first current collector in the first direction, at least one of the first surface and the second surface is provided with a thinning area connected to the pole lug groove, the thinning area includes a first recessed portion spaced apart from the pole lug groove in the first direction, and a second recessed portion arranged between the first recessed portion and the pole lug groove, the second direction is defined as the width direction of the first current collector, and when viewed along the second direction, the bottom wall of the second recessed portion is separated by the pole lug groove to form two first step surfaces spaced apart, and the bottom wall of the first recessed portion is separated by the second recessed portion to form two second step surfaces spaced apart; The first insulating layer is disposed in the second recess, and two ends of the first insulating layer are respectively located on the two first step surfaces; The second insulating layer is connected to a side of the second pole piece facing the first concave portion, and a projection of the second insulating layer in the first direction is located in the first concave portion; Along the first direction, the relationship between the depth T1 of the first recess, the depth T2 of the second recess, the thickness L1 of the first insulating layer, and the thickness L2 of the second insulating layer satisfies: T1≤L2, T2≥L1, T1≤5μm, 5μm≤L2≤20μm.

2. The electrode assembly according to claim 1, characterized in that 1μm≤T1≤3μm.

3. An electrode assembly, comprising a first pole piece, a separator and a second pole piece arranged in sequence, the electrode assembly further comprising a pole ear, a first insulating layer and a second insulating layer, the first pole piece comprising a first current collector and a first active material layer coated on both sides of the first current collector in a first direction, the first direction being the thickness direction of the first current collector, the first active material layer being provided with a pole ear groove exposing the first current collector, the pole ear groove being provided with a pole ear connected to the first current collector, characterized in that: The first active material layer includes a first surface and a second surface arranged opposite to each other in the first direction, the first surface and the second surface are away from the first current collector in the first direction, at least one of the first surface and the second surface is provided with a thinning area connected to the pole lug groove, the thinning area includes a first recessed portion spaced apart from the pole lug groove in the first direction, and a second recessed portion arranged between the first recessed portion and the pole lug groove, the second direction is defined as the width direction of the first current collector, and when viewed along the second direction, the bottom wall of the second recessed portion is separated by the pole lug groove to form two first step surfaces spaced apart, and the bottom wall of the first recessed portion is separated by the second recessed portion to form two second step surfaces spaced apart; The first insulating layer is disposed in the second recess, and two ends of the first insulating layer are respectively located on the two first step surfaces; The second insulating layer is connected to a side of the second pole piece facing the first concave portion, and along the first direction, a projection of the second insulating layer in the first direction is located in the first concave portion; Observing along the second direction, the first active material layer is also provided with flat coating areas located on both sides of the thinning area, and the electrode assembly also includes two third insulating layers connected to the two ends of the second insulating layer, and the projection of each of the third insulating layers in the first direction extends from the first recess to the flat coating area.

4. The electrode assembly according to claim 3, characterized in that Along the first direction, the relationship between the depth T1 of the first recess, the depth T2 of the second recess, the thickness L1 of the first insulating layer, and the thickness L2 of the second insulating layer satisfies: T1≥L2, T2≥L1, T1>5μm.

5. The electrode assembly according to claim 3, characterized in that: The third insulating layer is formed by coating polyvinyl alcohol or polyacrylic acid or a mixture of the two on the second pole piece.

6. The electrode assembly according to claim 3, characterized in that Along the first direction, a thickness L3 of the third insulating layer satisfies: 2 μm≤L3≤5 μm.

7. The electrode assembly according to claim 3, characterized in that The third direction is defined as the length direction of the first current collector. Along the third direction, the length D3 of the third insulating layer satisfies: 4 mm ≤ D3 ≤ 8 mm.

8. The electrode assembly according to claim 1 or 3, characterized in that: The third direction is defined as the length direction of the first current collector. Along the third direction, the relationship among the length W1 of the first recess, the length W2 of the second recess, the length D1 of the first insulating layer and the length D2 of the second insulating layer satisfies: W1≥D2, W2≥D1, W1>W2, D2>D1.

9. The electrode assembly according to claim 1 or 3, characterized in that: The thinning zone includes a first thinning zone and a second thinning zone, the first thinning zone is arranged on the first surface, and the second thinning zone is arranged on the second surface. Along the first direction, the projection of the first recess in the first thinning zone overlaps with the projection of the first recess in the second thinning zone, and the projection of the second recess in the first thinning zone overlaps with the projection of the second recess in the second thinning zone.

10. The electrode assembly according to claim 1 or 3, characterized in that: The first current collector located in the electrode tab groove is provided with a third recessed portion sunken along a first direction, and the electrode tab is accommodated in the third recessed portion.

11. The electrode assembly according to claim 1 or 3, characterized in that: The first active material layer includes a first surface and a second surface disposed opposite to each other in the first direction, the first active material layer is provided with a thinning area, and the thinning area is disposed on one of the first surface and the second surface. The electrode assembly further includes a fourth insulating layer and a fifth insulating layer, wherein the fourth insulating layer is connected to the other of the first surface and the second surface, the fourth insulating layer covers an end of the pole lug groove away from the thinning area, and the fifth insulating layer is connected to a side of the second pole piece facing the fourth insulating layer. Along the first direction, a projection of the first insulating layer overlaps with a projection of the fourth insulating layer, and a projection of the second insulating layer overlaps with a projection of the fifth insulating layer.

12. The electrode assembly according to claim 11, characterized in that Along the first direction, the relationship among the depth T1 of the first recess, the depth T2 of the second recess, the thickness L1 of the first insulating layer, the thickness L2 of the second insulating layer, the thickness L4 of the fourth insulating layer, and the thickness L5 of the fifth insulating layer satisfies: L1+L4≤T2, L2+L5≤T1.

13. A battery, characterized in that: The battery comprises the electrode assembly according to any one of claims 1 to 12.

14. An electrical device, characterized in that: The electrical device further comprises a battery as claimed in claim 13.

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