Electrochemical devices and electronic devices

Abstract

An electrochemical device includes an electrode assembly and a conductive plate. The electrode assembly is a wound structure and includes a first electrode plate. The first electrode plate includes a first conductive layer and a first conductive material layer. The first conductive layer includes a first surface and a second surface, with the first conductive material layer being disposed on the first surface. The first surface includes a first region. The conductive plate connects to the first region and extends beyond the first electrode plate. The conductive plate includes a third region and a fourth region connected to each other. The third region includes a connection region, and the conductive plate is connected to the first region via the connection region. The third region includes a first side, a second side, a third side, and a fourth side. The first region includes a fifth side, a sixth side, and a seventh side. The dimension of the third region in the third direction is defined as T1, the dimension of the third region in the second direction is defined as T2, the area of the third region is defined as S1, the area of the connection region is defined as S2, the distance between the first side and the fifth side is defined as J1, the distance between the second side and the sixth side is defined as J2, and the distance between the third side and the seventh side is defined as J3, where S2 / S1+(J1+J2+J3) / (T1+T2)≥30%. The present application also provides an electronic device.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to an electrochemical device and an electronic device having the electrochemical device. Background Art

[0002] Electrochemical devices (such as batteries) are widely used in electronic products such as electronic mobile devices, power tools and electric vehicles, and people have increasingly higher requirements for the safety performance of electrochemical devices.

[0003] When electrochemical devices are charged at high rates, they are prone to continuous heat generation and temperature rise due to factors such as their own internal resistance and polarization accumulation caused by charging. This may accelerate the aging of the electrochemical device, leading to a decline in capacity and power performance, and may also cause volume expansion and deformation, thereby affecting the life of the product. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, it is necessary to propose an electrochemical device that can improve the temperature rise problem during the charging process.

[0005] In addition, it is also necessary to provide an electronic device having the electrochemical device.

[0006] The present application provides an electrochemical device comprising an electrode assembly and a first conductive plate. The electrode assembly has a wound structure and includes a first electrode plate. The first electrode plate includes a first conductive layer and a first conductive material layer. The first conductive layer includes a first surface and a second surface facing each other, with the first conductive material layer disposed on the first surface. The first surface includes a first region, and the first conductive material layer includes a first recess, with the first region exposed in the first recess. The first conductive plate connects to the first region and extends beyond the first electrode plate. The first conductive plate includes a third region and a fourth region connected to each other. A direction perpendicular to the third region is defined as a first direction. In the first direction, the projection of the third region lies within the projection of the first region, and the projection of the fourth region lies outside the projection of the first region. The third region includes a connection region, through which the first conductive plate connects to the first region. Viewed from the first direction, the third region includes a first side, a second side, a third side, and a fourth side. The first side and the second side are opposite, the third side and the fourth side are opposite, and the fourth side connects to the fourth region. The first region includes a fifth side, a sixth side, and a seventh side. The third region extends in a second direction. In the second direction, the seventh side and the third side are sequentially arranged. In the third direction, the fifth side, the first side, the second side, and the sixth side are sequentially arranged. The first, second, and third directions are mutually perpendicular. The dimension of the third region in the third direction is defined as T1, the dimension of the third region in the second direction is defined as T2, the area of the projection of the third region in the first direction is defined as S1, the area of the projection of the connection region in the first direction is defined as S2, the distance between the first and fifth sides is defined as J1, the distance between the second and sixth sides is defined as J2, and the distance between the third and seventh sides is defined as J3. Therefore, S2 / S1+(J1+J2+J3) / (T1+T2) is ≥ 30%.

[0007] In the present application, S2 / S1 can reflect the proportion of the flow area of the first conductive plate. When S2 / S1 is large, the flow area of the first conductive plate increases, and the current distribution on the first conductive plate during charging of the electrochemical device is more dispersed and uniform, thereby making the heat generated at the first conductive plate during high-current charging more dispersed, reducing the risk of local overheating of the first conductive plate. Furthermore, (J1+J2+J3) / (T1+T2) can reflect the proportion of the area available for heat dissipation in the first zone. When (J1+J2+J3) / (T1+T2) is large, the heat dissipation area of the first conductive plate increases, thereby reducing the temperature rise during high-current charging. Therefore, the present application defines the sum of S2 / S1 and (J1+J2+J3) / (T1+T2) as ≥30%, thereby improving the safety and reliability of the electrochemical device.

[0008] In some possible implementations, the first electrode plate further includes a second conductive material layer disposed on the second surface. The second surface includes a second region, the second conductive material layer includes a second recess, and the second region is exposed in the second recess. In the first direction, the projection of the first region and the projection of the second region at least partially overlap. Thus, heat generated by the first conductive plate can be dissipated not only through the first region exposed to the first conductive plate but also through the overlap between the first and second regions to the second region, where it can be dissipated, further improving heat dissipation efficiency.

[0009] In some possible implementations, the electrochemical device further includes a first layer bonded to the third region, the first layer comprising an insulating material. In the first direction, the projection of the third region lies within the projection of the first layer. The first layer can reduce the risk of burrs or weld marks in the connection region piercing the separator and causing a short circuit. It can also compensate for the reduced thickness of the first conductive material layer at that location due to the provision of the first recess, thereby achieving a more uniform thickness across the electrochemical device.

[0010] In some possible implementations, the first conductive material layer includes a first conductive material region, the first conductive material region enclosing a first recess. The first layer is further bonded to the first conductive material region. In the first direction, a projection of the first region is located within a projection of the first layer.

[0011] In some possible implementations, the electrochemical device further includes a second layer comprising an insulating material. The second conductive material layer includes a second conductive material region, which surrounds a second recess. The second layer is bonded to the second conductive material region. In the first direction, a projection of the second region lies within a projection of the second layer. The second layer can be used to compensate for a thickness reduction at the location of the second conductive material layer caused by the second recess.

[0012] In some possible implementations, when viewed from the first direction, the first layer includes an eighth side. In the second direction, the seventh side is located between the eighth side and the third side. The distance between the edge of the first region in the second direction and the eighth side is defined as L1, and the distance between the seventh side and the eighth side is defined as L3, where L3 / L1 ≤ 30%. Consequently, in the second direction, the size of the first conductive material region covered by the first layer is reduced, meaning that less active material is covered by the first layer and less likely to contribute to capacity, thereby reducing the impact of the first layer on the capacity of the electrochemical device.

[0013] In some possible implementations, a third recess is provided at an edge of the first region in the second direction. The first conductive material region includes a first extension region and a second extension region extending toward the third recess. When viewed from the first direction, the first extension region and the second extension region are located on either side of the third recess. Consequently, when the electrode piece is striped, the uniform thickness of the electrode piece at the cut reduces the risk of wavy edges at the cut.

[0014] In some possible implementation manners, define the distance between the edge of the first region in the second direction and the eighth side as L1, the sizes of the first extension region and the second extension region in the second direction are the same and both are L2, and the distance between the seventh side and the eighth side is L3, then (L2 + L3) / L1 ≤ 30%. Thus, in the second direction, the size of the first conductive material region covered by the first layer is reduced, that is, the active material that cannot play a capacity role and is covered by the first layer is reduced, thereby reducing the influence of the first layer on the capacity of the electrochemical device.

[0015] In some possible implementation manners, define the size of the first extension region in the third direction as W1, the size of the second extension region in the third direction as W2, then (W1 + W2) / T1 ≥ 20%. Thus, the situation that the area available for heat dissipation in the first region is reduced due to the setting of the third recess is improved.

[0016] In some possible implementation manners, define the size of the first extension region in the third direction as W1, the size of the second extension region in the third direction as W2, the distance between the first extension region and the first conductive plate in the third direction as W3, and the distance between the second extension region and the first conductive plate in the third direction as W4. In some possible implementation manners, W3 < W1. In some possible implementation manners, W2 < W4. In some possible implementation manners, W3 < W4.

[0017] In some possible implementation manners, in the third direction, the first extension region and the second extension region respectively include a ninth side and a tenth side. The first region connects the ninth side and the tenth side. The ninth side and the tenth side are linear or arc-shaped.

[0018] In some possible implementation manners, in the second direction, the size of the first extension region and / or the second extension region is L2, the distance between the ninth side and the fourth side is L4, then L2 < L4. Since L4 is relatively large, it is beneficial to further increase the heat dissipation area of the first conductive plate, thereby reducing the temperature rise during high-current charging.

[0019] In some possible implementation manners, the range of L1 is 10 mm to 50 mm. When L1 is relatively large, the size of the first conductive material layer covered by the first layer in the second direction is relatively large, so the influence on the capacity of the electrochemical device is increased; when L1 is relatively small, the size of the first region in the second direction is also small, so the distance J3 between the third side and the seventh side is also small, and thus the heat dissipation capacity of the first region will be reduced.

[0020] In some possible implementations, the electrochemical device further includes a third layer and a fourth layer, both of which contain insulating materials. In the first direction, the first layer is arranged between the first conductive plate and the third layer, and the second layer is arranged between the first conductive plate and the fourth layer. The third layer and the fourth layer can further compensate for the reduction in thickness of the electrode at the first recess and the second recess. When the first electrode is a negative electrode and the second electrode is a positive electrode, the third layer can also be used to prevent the lithium ions released from the portion of the third conductive material layer corresponding to the third layer in the first direction from moving to the second recess, thereby reducing the risk of excessive lithium ion accumulation and the generation of lithium dendrites due to the lack of lithium ions embedded in the second recess. Similarly, the fourth layer can also reduce the risk of generating lithium dendrites.

[0021] In some possible implementations, the electrode assembly further includes a second electrode sheet, and at least one of the third layer or the fourth layer is bonded to the second electrode sheet, thereby securing the third layer and the fourth layer in the electrochemical device and compensating for thickness or reducing the risk of lithium dendrite formation.

[0022] In some possible implementations, in the second direction, an edge of at least one of the first layer or the second layer exceeds an edge of the first pole piece.

[0023] In some possible implementations, the connection region is welded to the first region, thereby achieving a high connection strength between the first conductive plate and the first region. The connection region includes multiple welding points. Area S2 is the sum of the projection areas of the multiple welding points in the first direction.

[0024] In some possible implementations, the electrode assembly further includes a second electrode sheet and a separator, and the first electrode sheet, separator, and second electrode sheet are stacked and wound to form the electrode assembly. In the winding direction, the electrode assembly includes a first section, a first bend section, a second section, and a second bend section, which are sequentially connected. The first conductive plate is located in the first section, thereby improving the flatness of the first conductive plate when connected to the first region.

[0025] In some possible implementations, the housing includes a main body for accommodating the electrode assembly and a sealing edge connected to the main body, wherein the sealing edge includes a polymer layer, and the fourth region extends out of the housing from the polymer layer.

[0026] The present application also provides an electronic device comprising the above electrochemical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the overall structure of an electrochemical device provided in one embodiment of the present application.

[0028] Figure 2 for Figure 1 Schematic diagram of the structure of the electrochemical device before packaging.

[0029] Figure 3A for Figure 1 A top view of an electrode assembly of an electrochemical device is shown.

[0030] Figure 3B for Figure 1 Schematic diagram of the preparation of the edge sealing of the casing of the electrochemical device shown.

[0031] Figure 4 for Figure 3A An enlarged view of the electrode assembly at IV is shown.

[0032] Figure 5 for Figure 3A An enlarged view of the electrode assembly at position V is shown.

[0033] Figure 6 for Figure 3A The diagram shows the front and back structures of the first electrode sheet of the electrode assembly after unfolding.

[0034] Figure 7 for Figure 3A A front view of the connection between the first pole piece and the first conductive plate is shown.

[0035] Figure 8A To remove Figure 7 A front view of the first layer on the first pole piece is shown.

[0036] Figure 8B In some other embodiments, Figure 7 A front view of the first layer on the first pole piece is shown.

[0037] Figure 8C for Figure 8B Schematic diagram of the projection of the third region of the first conductive plate is shown.

[0038] Figure 8D for Figure 8B A schematic projection diagram of the connection area of the third zone is shown.

[0039] Figure 9 This is a front view of the connection between the first electrode and the first conductive plate in an electrochemical device according to another embodiment of the present application.

[0040] Figure 10A To remove Figure 9 A front view of the first layer on the first pole piece is shown.

[0041] Figure 10B In some other embodiments, Figure 9 A front view of the first layer on the first pole piece is shown.

[0042] Figure 10C In some other embodiments, Figure 9A front view of the first layer on the first pole piece is shown.

[0043] Figure 10D In some other embodiments, Figure 9 A front view of the first layer on the first pole piece is shown.

[0044] Figure 10E In some other embodiments, Figure 9 A front view of the first layer on the first pole piece is shown.

[0045] Figure 11 It is a front view of the connection between the first electrode and the first conductive plate in some other embodiments.

[0046] Figure 12 To remove Figure 11 A front view of the first layer on the first pole piece is shown.

[0047] Figure 13 This is a front view of the connection between the first electrode and the first conductive plate in an electrochemical device according to another embodiment of the present application.

[0048] Figure 14 This is a schematic diagram of the overall structure of an electronic device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application are described clearly and in detail below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present application. The terms used 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.

[0050] Below, embodiments of the present application will be described in detail. However, the present application may be embodied in many different forms and should not be construed as limited to the exemplary embodiments illustrated herein. Rather, these exemplary embodiments are provided to make the present application thorough and detailed for those skilled in the art.

[0051] In addition, for the sake of brevity and clarity, the size or thickness of various components or layers may be exaggerated in the accompanying drawings. Throughout the text, the same numerical value refers to the same element. As used herein, the terms "and / or" and "and / or" include any and all combinations of one or more related enumerated items. In addition, it should be understood that when element A is referred to as "connecting" element B, element A can be directly connected to element B, or there may be an intermediate element C and element A and element B can be indirectly connected to each other.

[0052] Further, when describing embodiments of the present application, the use of “may” refers to “one or more embodiments of the present application.”

[0053] The technical terms used herein are for the purpose of describing specific embodiments and are not intended to limit this application. As used herein, the singular is intended to include the plural, unless the context clearly indicates otherwise. It should be further understood that the term "comprising", when used in this specification, refers to the presence of the described features, values, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, values, steps, operations, elements, components and / or combinations thereof.

[0054] Spatial related terms, such as "on" etc., can be used herein for convenient description, to describe the relationship between an element or feature and another element (multiple elements) or feature (multiple features) as illustrated in the figure. It should be understood that, in addition to the directions described in the figure, spatial related terms are intended to include different directions of equipment or devices in use or operation. For example, if the equipment in the figure is turned over, the elements described as "above" or "on" other elements or features will be oriented "below" or "below" other elements or features. Therefore, the exemplary term "on" can include the direction above and below. It should be understood that although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are used to distinguish an element, component, region, layer or part from another element, component, region, layer or part. Therefore, the first element, component, region, layer or part discussed below can be referred to as the second element, component, region, layer or part, without departing from the teachings of the exemplary embodiments.

[0055] See also Figure 1 and Figure 2 In one embodiment of the present application, an electrochemical device 100 is provided, comprising a housing 10, an electrode assembly 20, a first conductive plate 30, and a second conductive plate 40. The electrode assembly 20 is located within the housing 10 and has a wound structure. The first conductive plate 30 and the second conductive plate 40 are both electrically connected to the electrode assembly 20 and extend from the interior of the housing 10 out of the housing 10. Figure 2 The number of electrode assemblies 20 is shown as one. In other embodiments, the number of electrode assemblies 20 can also be multiple, and multiple electrode assemblies 20 are located in the housing 10 and are electrically connected in parallel or in series. Figure 3A The electrode assembly 20 includes a first electrode 21, a second electrode 22 and a separator 23, wherein the separator 23 is disposed between the first electrode 21 and the second electrode 22. The first electrode 21, the separator 23 and the second electrode 22 are sequentially stacked and wound to form the electrode assembly 20. Figure 3AAs shown, the electrode assembly 20 has a winding center axis C perpendicular to the paper. The winding direction D is Figure 3A The direction shown is a counterclockwise rotation direction around the winding center axis C. In some embodiments, the winding direction D can also be a counterclockwise rotation direction.

[0056] In the present application, a first three-dimensional coordinate system is established based on a first direction D1, a second direction D2, and a third direction D3 that are perpendicular to each other. The first direction D1 is a direction perpendicular to the third area 31 of the first conductive plate 30. The second direction D2 is an extension direction of the third area 31 of the first conductive plate 30. When the pole piece is unfolded, a second three-dimensional coordinate system is established by defining the first direction D1, the second direction D2, and the fourth direction D4 that are perpendicular to each other. The fourth direction D4 is the direction from the winding start end to the winding end end before the pole piece is wound, such as the fourth direction D4 is the direction from the first winding start end 21a to the first winding end end 21b of the first pole piece 21 before winding, and is also the direction from the second winding start end 22a to the second winding end end 22b of the second pole piece 22 before winding.

[0057] In some embodiments, in the winding direction D, the electrode assembly 20 includes a first segment 201, a first bent segment 202, a second segment 203, and a second bent segment 204 connected in sequence. The first direction D1 is the stacking direction of the first electrode sheet 21 in the first segment 201 or the second segment 203. The electrode assembly 20 may have a plurality of first segments 201, a plurality of first bent segments 202, a plurality of second segments 203, and a plurality of second bent segments 204. In some embodiments, the first segment 201 and the second segment 203 may be straight segments. In other embodiments, in the winding direction D, the electrode assembly 20 may also include four bent segments connected in sequence.

[0058] The first segment 201 has a first outer surface 201a, and the second segment 203 has a second outer surface 203a. The connection between the first segment 201 located at the outermost side of the electrode assembly 20 and the first bent segment 202 located at the outermost side of the electrode assembly 20 is the first end 205. The first end 205 is Figure 3A The first end 205 is also the portion where the dotted line BB formed by the rightmost bending edge of the first bending section 202 located at the innermost and right side of the electrode assembly 10 intersects with the first outer surface 201a in the first direction D1. The connection between the first bending section 202 located at the outermost side of the electrode assembly 20 and the second section 203 located at the outermost side of the electrode assembly 20 is the second end 206. The second end 206 is Figure 3AThe second end 206 is the portion where the rightmost bending edge of the first bending section 202 in the winding direction D ends, and the second end 206 is the portion where the dotted line BB formed by the bending edge located at the innermost and right side of the electrode assembly 10 and extending in the first direction D1 intersects with the second outer surface 203a. The connection between the second section 203 located at the outermost side of the electrode assembly 20 and the second bending section 204 located at the outermost side of the electrode assembly 20 is the third end 207. The third end 207 is Figure 3A The third end 207 is also the portion where the dotted line AA formed by the leftmost curved edge of the electrode assembly 10 extending in the first direction D1 intersects with the second outer surface 203a. The connection between the outermost second curved segment 204 of the electrode assembly 20 and the outermost first segment 201 of the electrode assembly 20 is the fourth end 208. The fourth end 208 is Figure 3A The fourth end 208 is the portion where the leftmost curve of the second bent section 204 ends in the winding direction D. The fourth end 208 is also the portion where the dashed line AA extending from the innermost and left-side bent edge of the electrode assembly 10 intersects the first outer surface 201a in the first direction D1. In the first direction D1, the first end 205 and the second end 206 are aligned, and the third end 207 and the fourth end 208 are aligned.

[0059] Please refer to Figure 3A 、 Figures 4 and 5 The first pole piece 21 includes a first conductive layer 210, a first conductive material layer 211, and a second conductive material layer 212. The first conductive layer 210 includes a first surface 210a and a second surface 210b facing each other in the first direction D1, the first conductive material layer 211 is provided on the first surface 210a, and the second conductive material layer 212 is provided on the second surface 210b. The second pole piece 22 includes a second conductive layer 220, a third conductive material layer 221, and a fourth conductive material layer 222. The second conductive layer 220 includes a third surface 220a and a fourth surface 220b facing each other in the first direction D1, the third material layer 221 is provided on the third surface 220a, and the fourth conductive material layer 222 is provided on the fourth surface 220b. The second conductive material layer 212 and the third conductive material layer 221 face each other in the first direction D1 via the isolation film 23. In some embodiments, as Figure 3AAs shown, after being stacked and wound, the first surface 210a of the first conductive layer 210 is away from the winding center axis C, and the second surface 210b is toward the winding center axis C. The third surface 220a of the second conductive layer 220 is away from the winding center axis C, and the fourth surface 220b is toward the winding center axis C. It will be understood that in other embodiments, the first surface 210a of the first conductive layer 210 may be toward the winding center axis C, and the second surface 210b is away from the winding center axis C. In this case, the third surface 220a of the second conductive layer 220 is toward the winding center axis C, and the fourth surface 220b is away from the winding center axis C.

[0060] The first electrode sheet 21 can be a positive electrode sheet or a negative electrode sheet. Correspondingly, the first conductive layer 210 can be a positive electrode conductive layer or a negative electrode conductive layer, and the first conductive material layer 211 and the second conductive material layer 212 can both be positive electrode active material layers or negative electrode active material layers. The first conductive layer 210 can have the function of collecting current. The second electrode sheet 22 can be a negative electrode sheet or a positive electrode sheet. Correspondingly, the second conductive layer 220 can be a negative electrode conductive layer or a positive electrode conductive layer, and the third conductive material layer 221 and the fourth conductive material layer 222 can both be negative electrode active material layers or positive electrode active material layers. The second conductive layer 220 can have the function of collecting current. In some embodiments, the first electrode sheet 21 is a positive electrode sheet, and the second electrode sheet 22 is a negative electrode sheet. The positive electrode conductive layer can be made of aluminum foil or nickel foil, and the negative electrode conductive layer can be made of at least one of copper foil, nickel foil, or a carbon-based conductive layer.

[0061] The positive electrode active material layer contains a positive electrode active material, which includes a compound that reversibly intercalates and deintercalates lithium ions (i.e., a lithiated intercalation compound). In some embodiments, the positive electrode active material may include a lithium transition metal composite oxide. The lithium transition metal composite oxide contains lithium and at least one element selected from cobalt, manganese, and nickel. In some embodiments, the positive electrode active material is selected from lithium cobalt oxide (LiCoO2), lithium nickel manganese cobalt ternary material (NCM), lithium manganese oxide (LiMn2O4), lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) or at least one of lithium iron phosphate (LiFePO4).

[0062] The negative electrode active material layer contains a negative electrode active material, which is a negative electrode active material known in the art that can reversibly deintercalate active ions, and is not limited in this application. For example, it can be a combination of one or more of graphite, soft carbon, hard carbon, carbon fiber, mesophase carbon microspheres, silicon-based materials, tin-based materials, lithium titanate, or other metals that can form alloys with lithium. Among them, graphite can be selected from a combination of one or more of artificial graphite, natural graphite, and modified graphite; silicon-based materials can be selected from a combination of one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, and silicon alloys; tin-based materials can be selected from a combination of one or more of elemental tin, tin oxide compounds, and tin alloys.

[0063] The separator 23 includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid. For example, the polyethylene includes at least one selected from high-density polyethylene, low-density polyethylene, or ultra-high molecular weight polyethylene. Polyethylene and polypropylene are particularly effective in improving short circuits and can improve battery stability through a shutdown effect.

[0064] Please refer to Figure 4 、 Figures 6 to 8AThe first surface 210a of the first conductive layer 210 includes a first region 2100. The first conductive material layer 211 includes a first recess 2110. The first recess 2110 can be formed by extending inward from the first end 211a of the first conductive material layer 211 in the direction of the winding center axis C. The first recess 2110 does not extend through the second end 211b of the first conductive material layer 211 in the direction of the winding center axis C. The first region 2100 is exposed in the first recess 2110 and is separated from the first conductive material layer 211. Specifically, laser cleaning can be used to remove the first recess 2110 from the first conductive material layer 211, thereby exposing the first region 2100. Alternatively, foam glue can be applied to the first region 2100 in advance, and then heated after coating the active material to remove the foam glue, thereby exposing the first region 2100. Alternatively, the active material on the first region 2100 can be directly scraped off with a scraper, thereby exposing the first region 2100. However, it is understandable that after laser cleaning or scraping with a scraper, a small amount of active material may remain on the surface of the first area 2100, and this application does not limit this. Observed along the first direction D1, the first conductive plate 30 connects to the first area 2100 and extends from the first area 2100 to outside the first area 2100 beyond the first end edge 211a, so that external components (not shown) can be connected. In order to meet the needs of high-current charging, the first area 2100 can be provided in an area of the first pole piece 21 other than the winding head and the winding tail. In some embodiments, the projections of the first area 2100 and the first recess 2110 in the first direction D1 may both be rectangular. In some specific embodiments, the projections of the first area 2100 and the first recess 2110 in the first direction D1 are both rectangular.

[0065] In some embodiments, the housing 10 may be a packaging bag encapsulated with a packaging film (such as an aluminum-plastic film), that is, the electrochemical device 100 may be a soft-pack battery. Figure 1 and Figure 2The shell 10 includes a main body 11 for accommodating the electrode assembly 20 and a sealing edge 12 connected to the main body 11. The main body 11 includes a first wall 111 and a second wall 112 facing each other in the second direction D2. The sealing edge 12 is connected to the first wall 111 and also includes a third wall 113 and a second wall 114 facing each other in the second direction D2. In the second direction D2, the third wall 113 is arranged between the first wall 111 and the second wall 112, and the fourth wall 114 is also arranged between the first wall 111 and the second wall 112. The first conductive plate 30 and the second conductive plate 40 extend from the inside of the shell 10 to the outside of the shell 10 from the sealing edge 12 respectively. The shell 10 includes a first shell 13 and a second shell 14 arranged opposite to each other. The shell 10 can be heat-sealed by the first shell 13 and the second shell 14. The first shell 13 is provided with a first space 130, and the second shell 14 is a flat plate structure. Thus, after the first shell 13 and the second shell 14 are heat-sealed, the first space 130 is enclosed by the second shell 14 to form a storage space for accommodating the electrode assembly 20. Of course, the first shell 14 may also have a second space (not shown). After the first shell 13 and the second shell 14 are heat-sealed, the first space 130 and the second space cooperate to form a storage space for accommodating the electrode assembly 20.

[0066] See also Figure 3B, the first shell 13 and the second shell 14 can be obtained by folding a packaging film. That is, the first shell 13 and the second shell 14 are both multi-layer sheets, and the multi-layer sheet includes a protective layer 131, a metal layer 132 and a packaging layer 133 stacked in sequence. The material of the protective layer 131 can be a polymer material, which can be used to protect the metal layer 132, reduce the risk of damage to the metal layer 132 due to external force, and at the same time delay the air infiltration of the external environment, and maintain the electrochemical device 100 in a normal operating environment. The polymer material of the protective layer 131 can be selected from at least one of polyethylene terephthalate, polybutylene terephthalate, polyvinylidene fluoride, polytetrafluoroethylene, polypropylene, polyamide, and polyimide. The metal layer 132 can be used to delay the moisture infiltration of the external environment and reduce the damage to the electrode assembly 20 caused by external force. In some embodiments, the metal layer 132 can be an aluminum foil layer or a steel foil layer. The encapsulation layer 133 can be used for encapsulation, which can reduce the risk of the multilayer sheet being dissolved or swelled by the organic solvent in the electrolyte. The encapsulation layer 133 can also be used to reduce the risk of the electrolyte in the electrolyte contacting the metal layer 132 and causing the metal layer to corrode. The encapsulation layer 133 includes a polymer material with the property of melting when heated. The polymer material can be selected from at least one of polypropylene, propylene copolymer, polyethylene, and polymethyl methacrylate. When preparing the shell 10, a certain temperature and pressure can be applied to the edges of the first shell 13 and the second shell 14 using an encapsulation head at the same time, so that the encapsulation layer 133 of the first shell 13 and the encapsulation layer 133 of the second shell 14 melt and bond together to obtain a polymer layer 134. Therefore, after the edge seal 12 is formed by heat sealing, the edge seal 12 may include a protective layer 131, a metal layer 132, a polymer layer 134, a metal layer 132, and a protective layer 131 stacked in sequence.

[0067] In other embodiments, the electrochemical device 100 is not limited to a soft-pack battery, and may also be a steel-shell battery or an aluminum-shell battery, etc., which is not limited in this application.

[0068] An electrochemical device 200 includes an electrode assembly 20 and a first conductive plate 30. The electrode assembly 20 includes a first electrode plate 21. The first electrode plate 21 includes a first conductive layer 210 and a first conductive material layer 212.

[0069] The first conductive layer 210 includes a first surface 210a and a second surface 210b facing opposite to the first surface 210a. When viewed along a first direction D1 perpendicular to the first surface 210a, the first conductive layer 210 further includes a first end side 211b in a second direction D2 perpendicular to the first direction D1, and a second end side 211a located on the opposite side of the first end side 211b in the second direction D2 and having a third recess R when viewed along the second direction D2.

[0070] The first conductive material layer 211 is disposed on the first surface 210a of the first conductive layer 210, separated from at least a portion of the fourth recess 4, and disposed from the second end side 211a to the first end side 211b;

[0071] The first conductive plate 30 is disposed on the first surface 210 a of the first conductive layer 210 , is separated from the first conductive material layer 210 , and overlaps with the third recess R when viewed along the first direction D1 .

[0072] As described above, in the electrochemical device, when viewed along the first direction D1 , the first conductive material layer 210 includes a portion connected to the second end side 210 a and the side of the third recess R.

[0073] As the electrochemical device described above, when viewed along the first direction D1 , in a third direction D3 perpendicular to the second direction D2 , the first conductive material layer 210 includes a first side R1 connected to the second end 211 a and opposite to the first conductive plate 30 .

[0074] As the electrochemical device described above, when viewed along the first direction D1 , in the third direction D3 , the first conductive material layer 210 includes a fifth edge 2101 separated from the first side edge R1 and opposite to the first conductive plate 30 .

[0075] As described above, in the electrochemical device, the first conductive material layer 210 includes a ninth side 2114 connected to the first side R1 and the fifth side 2101 .

[0076] As described above, in the electrochemical device, in the third direction D3 , the distance W3 from the first conductive plate 30 to the first side R1 is shorter than the distance W1 from the first side R1 to the fifth side 2101 in the third direction D3 .

[0077] As described above, the electrochemical device, wherein: when viewed along the first direction D1, the first conductive material layer 210 includes a portion connected to the second end edge 210a and the third recess R, and when viewed along the first direction D1, in a third direction D3 perpendicular to the second direction D2, further includes a second side edge R2 connected to the second end edge 211a and opposite to the first conductive plate 30, and a sixth side 2102 separated from the second side edge R2 and opposite to the first conductive plate 30.

[0078] As described above, in the electrochemical device, the first conductive material layer 210 includes a tenth side 2115 connected to the second side R2 and the sixth side 2102 .

[0079] As described above, in the electrochemical device, in the third direction D3 , the distance W4 from the first conductive plate 30 to the second side R2 is longer than the distance W2 from the second side R2 to the tenth side 2115 .

[0080] As described above, in the electrochemical device, in the third direction D3 , the distance W3 from the first conductive plate 30 to the first side R1 is shorter than the distance W4 from the first conductive plate 30 to the second side R2 .

[0081] In the electrochemical device described above, a distance L2 from the second end side 211a to the ninth side 2114 in the second direction D2 is shorter than a distance L4 from the ninth side 2114 to the bottom side R3 of the third recess R in the second direction D2.

[0082] As the electrochemical device described above, the third recess R includes a slope edge R extending from the second end edge 211a to the bottom edge R3 of the third recess. 11 .

[0083] As described above, the electrochemical device, wherein the electrode assembly 20 includes a first layer 50 that covers at least a portion of the first electrode plate 30 and the first side R1 and includes an insulating material.

[0084] like Figure 7 and Figure 8A As shown, the first conductive plate 30 includes a third area 31 and a fourth area 32 connected to the third area 31. In the first direction D1, the projection of the third area 31 is located within the projection of the first area 2100, that is, the projection of the third area 31 coincides with at least a portion of the projection of the first area 2100, while the projection of the fourth area 32 is located outside the projection of the first area 2100. Figure 1 , the fourth area 32 extends out of the housing 10. Figure 1 and Figure 3B When the electrochemical device 100 is a pouch cell, the fourth region 32 extends out of the housing 10 from the polymer layer 134 within the edge seal 12. In some embodiments, the surface of the edge seal 12 is perpendicular to the surface of the first wall 111. In this case, the second direction D2 not only defines the extension direction of the third region 31 but also the extension direction of the entire first conductive plate 30. However, in other embodiments, the edge seal 12 can be folded over the first wall 111, thereby reducing the size of the electrochemical device 100 in the second direction D2 and improving space utilization and energy density. In this case, the second direction D2 is the extension direction of the third region 31, while the extension direction of the fourth region 32 within the edge seal 12 is perpendicular to the second direction D2.

[0085] The third region 31 includes a connection region 311 and an edge region 312 surrounding the connection region 311. The first conductive plate 30 is connected to the first region 2100 via the connection region 311. Specifically, the connection region 311 is where current flows during charging of the electrochemical device 100. In some embodiments, the first conductive plate 30 is welded to the first region 2100 via the connection region 311, thereby providing a high connection strength between the first conductive plate 30 and the first region 2100. The welding of the connection region 311 and the first region 2100 forms a plurality of welds 3110, securing the connection region 311 to the first region 2100 via the welds 3110. A large number of welds 3110 can reduce the contact resistance between the first conductive plate 30 and the first electrode 21, thereby reducing heat generation during charging of the electrochemical device 100. In other embodiments, the first conductive plate 30 can also be connected to the first region 2100 using conductive adhesive or other methods.

[0086] In some embodiments, as Figure 7 and Figure 8A As shown, when viewed from the first direction D1, the plurality of solder joints 3110 may be arranged in a single matrix. In this case, the edge region 312 is the region outside the outermost circle of solder pads 3110 in the third region 31. In other embodiments, such as Figure 8B As shown, the plurality of solder joints 3110 may also be arranged in a plurality of matrices, so that the connection region 311 includes a plurality of separated regions. In this case, the edge region 312 further includes regions in the third region 31 located between adjacent matrices.

[0087] like Figure 7 and Figure 8A As shown, when viewed from the first direction D1, the third area 31 may be roughly rectangular. The third area 31 includes a first side 3101, a second side 3102, a third side 3103, and a fourth side 3104. The first side 3101 and the second side 3102 are opposite to each other in the third direction D3. The third side 3103 and the fourth side 3104 are opposite to each other in the second direction D2. The third side 3103 connects the two ends where the first side 3101 and the second side 3102 are connected, and the fourth side 3104 connects the two ends where the first side 3101 and the second side 3102 are connected. Moreover, the fourth side 3104 is the dividing line between the third area 31 and the fourth area 32. In some embodiments, the first side 3101 and the second side 3102 extend along the second direction D2, respectively, and the third side 3103 and the fourth side 3104 extend along the third direction D3, respectively.

[0088] The first area 2100 includes a fifth side 2101, a sixth side 2102, and a seventh side 2103. The fifth side 2101 and the sixth side 2102 are opposite to each other in the third direction D3. The seventh side 2103 connects the two ends of the fifth side 2101 and the sixth side 2102. When viewed from the first direction D1, the seventh side 2103 faces the third end side 2104 of the first area 2100 in the second direction D2. It can be understood that the first recess 2110 is a three-dimensional structure. However, when viewed from the first direction D1, the first recess 2100 includes multiple edges connected in sequence (not shown in the figure). Moreover, when viewed from the first direction D1, the fifth side 2101, the sixth side 2102, and the seventh side 2103 of the first area 2100 respectively coincide with the edges of the first recess 2110. In some embodiments, the fifth side 2101 and the sixth side 2102 extend along the second direction D2, respectively, and the seventh side 2103 extends along the third direction D3. In the second direction D2, the seventh side 2103 and the third side 3103 are arranged in sequence, and the seventh side 2103 and the third side 3103 are at least partially opposite each other. In some embodiments, the seventh side 2103 and the third side 3103 may be parallel to each other. In the third direction D3, the fifth side 2101, the first side 3101, the second side 3102, and the sixth side 2102 are arranged in sequence, and the fifth side 2101 and the first side 3101 are at least partially opposite each other, and the second side 3102 and the sixth side 2102 are at least partially opposite each other. In some embodiments, the fifth side 2101, the first side 3101, the second side 3102, and the sixth side 2102 may be parallel to each other.

[0089] In the second direction D2, the seventh side 2103 and the third side 3103 are sequentially arranged, which means that a virtual straight line along the second direction D2 passes through the seventh side 2103 and the third side 3103 in sequence. In the third direction D3, the fifth side 2101, the first side 3101, the second side 3102, and the sixth side 2102 are sequentially arranged, which means that a virtual straight line along the third direction D3 passes through the fifth side 2101, the first side 3101, the second side 3102, and the sixth side 2102 in sequence. In some embodiments, the second direction D2 is the direction of the winding center axis C, and the third direction D3 is perpendicular to the second direction D2.

[0090] In some embodiments, as Figure 7 and Figure 8A As shown, the fifth side 2101, the sixth side 2102, and the seventh side 2103 are all straight lines. In other embodiments, when the first region 2100 is formed by laser cleaning or other methods, at least one of the fifth side 2101, the sixth side 2102, and the seventh side 2103 may also be concave or convex, which is not a limitation of the present application.

[0091] like Figure 7 and Figure 8AAs shown, in the third direction D3 , the first conductive plate 30 is disposed approximately in the middle of the first region 2100 .

[0092] The size of the third area 31 in the third direction D3 is defined as T1, the size of the third area 31 in the second direction D2 is defined as T2, and the area of the projection of the third area 31 in the first direction D1 is defined as S1 (in Figure 8C ), the projection area of the connection area 311 in the first direction D1 is S2 (in Figure 8D As shown in FIG, the distance between the first side 3101 and the fifth side 2101 is J1, the distance between the second side 3102 and the sixth side 2102 is J2, and the distance between the third side 3103 and the seventh side 2103 is J3, then the heat dissipation coefficient of the first zone 2100 is K=S2 / S1+(J1+J2+J3) / (T1+T2)≥30%.

[0093] Here, S2 / S1 reflects the area ratio of the connection region 311 to the third region 31, i.e., the ratio of the current flow area of the first conductive plate 30. When S2 / S1 is large, the current flow area of the first conductive plate 30 increases, and the current distribution on the first conductive plate 30 during charging of the electrochemical device 100 is more dispersed and uniform. This, in turn, disperses the heat generated on the first conductive plate 30 during high-current charging, reducing the risk of localized overheating of the first conductive plate 30. Furthermore, J1 reflects the length of the first region 2100 exposed from the first side 3101 of the first conductive plate 30, J2 reflects the length of the first region 2100 exposed from the second side 3102 of the first conductive plate 30, and J3 reflects the length of the first region 2100 exposed from the third side 3103 of the first conductive plate 30. Therefore, (J1+J2+J3) / (T1+T2) reflects the area ratio of the first region 2100 exposed from the first conductive plate 30, i.e., the area ratio of the first region 2100 available for heat dissipation. When (J1+J2+J3) / (T1+T2) is large, the heat dissipation area of the first conductive plate 30 increases, thereby reducing the temperature rise during high-current charging. Therefore, this application defines the heat dissipation coefficient K of the first region 2100 as the sum of S2 / S1 and (J1+J2+J3) / (T1+T2), and sets the heat dissipation coefficient K to ≥ 30%, thereby improving the safety and reliability of the electrochemical device 100.

[0094] Among them, J1, J2, J3, T1, and T2 can be measured respectively by direct measurement method, and the test steps include: disassembling the electrochemical device 100 and taking the first electrode piece 21 as a test sample; using a caliper or other suitable measuring tool to directly measure the values of J1, J2, J3, T1, and T2, or collecting an image of the first electrode piece 21 and performing measurements in the image.

[0095] S1 can be calculated based on T1, T2 and the specific shape of the third region 31. It can be understood that when the third region 31 is a rectangle, S1 is the product of T1 and T2.

[0096] In some embodiments, when the connection area 311 is welded to the first area 2100, S2 is the sum of the projection areas of the plurality of welding points 3110 in the first direction D1. Figure 8D As shown, if the number of solder joints 3110 is n (n is a natural number greater than 1), the projection areas of the n solder joints 3110 in the first direction D1 are S 21 、S 22 ,…S 2n , then S2=S 21 +S 22 +…+S 2n . Among them, S2 can be measured by the image method, and the test steps include: disassembling the electrochemical device 100, taking the first electrode 21 as the test sample, and collecting an image including the connection area 311 from the first direction D1, which is the first image; collecting an image of a reference target with a known area of S0, which is the second image; calculating the number n1 of pixels corresponding to the solder joint 3110 in the first image, and calculating the number n0 of pixels corresponding to the reference target in the second image; calculating the area S2 of the solder joint 3110 based on the area A0, the number n1 and the number n0, that is, S2 = (S0×n0) / n1. It can be understood that the test of S2 is not limited to the above method. In other embodiments, when the connection area 311 is connected to the first area 2100 in other ways, S1 can also be calculated based on the dimensions of each dimension of the connection area 311 and the specific shape of the connection area 311.

[0097] See also Figure 4 In some embodiments, the second surface 210b of the first conductive layer 210 includes a second region 2105. The second conductive material layer 212 includes a second recess 2120. The second region 2105 is exposed in the second recess 2120 and is separated from the second conductive material layer 212. However, it is understood that a small amount of active material may remain on the surface of the second region 2105, and this is not a limitation of the present application. In the first direction D1, the projection of the first region 2100 and the projection of the second region 2105 at least partially overlap. Therefore, heat generated by the first conductive plate 30 can not only be dissipated through the first region 2100 exposed in the first conductive plate 30, but can also be conducted to the second region 2105 through the overlap between the first region 2100 and the second region 2105, where it is dissipated, thereby further improving heat dissipation efficiency. In some specific embodiments, to further improve heat dissipation efficiency, the projection of the first region 2100 and the projection of the second region 2105 can be completely overlapped in the first direction D1.

[0098] It is understood that when the first conductive plate 30 is welded to the first area 2100 through the connection area 311, burrs or weld marks may be formed at the connection area 311, and the burrs or weld marks may pierce the isolation film 23, thereby causing a short circuit. Figure 4 、 Figure 6 and Figure 7 As shown, in some embodiments, the electrochemical device 100 further includes a first layer 50 bonded to at least the third region 31. The first layer 50 comprises an insulating material. In the first direction D1, the projection of the first region 2100 lies within the projection of the first layer 50. That is, the first layer 50 at least completely covers the third region 31. Furthermore, the first layer 50 can at least completely cover the first region 2100. The first layer 50 can reduce the risk of burrs or weld marks in the connection region 311 piercing the separator 23 and causing a short circuit. Furthermore, the first layer 50 can also compensate for the reduced thickness of the first conductive material layer 211 at that location due to the provision of the first recess 2110, thereby achieving a more uniform thickness across the electrochemical device 100. The first layer 50 can be single-sided or double-sided adhesive tape, and the specific material can be selected from at least one of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, or polyethylene glycol. In other embodiments, the first layer 50 can also be a ceramic coating.

[0099] In some embodiments, the first layer 50 may also extend beyond the first region 2100 and cover and adhere to a portion of the first conductive material layer 211. Specifically, the first conductive material layer 211 includes a first conductive material region 2111, which surrounds and forms a first recess 2110. The first layer 50 also adheres to the first conductive material region 2111. Figure 7 and Figure 8A The first conductive material region 2111 and other regions of the first conductive material layer 211 are shown as being filled in different ways. However, it should be understood that this does not mean that the first conductive material region 2111 and other regions of the first conductive material layer 211 are made of different active materials, and there is no clear boundary between the two.

[0100] like Figure 7As shown, when viewed from the first direction D1, the first layer 50 includes an eighth side 51. In the second direction D2, the seventh side 2103 is located between the eighth side 51 and the third side 3103. The distance between the third end side 2104 of the first region 2100, which is opposite the seventh side 2103 in the second direction D2, and the eighth side 51 can be defined as L1, and the distance between the seventh side 2103 and the eighth side 51 can be defined as L3, with L3 / L1 ≤ 30%. It can be understood that because the first conductive material region 2111 is covered by the first layer 50, the material within the first conductive material region 2111 is less likely to contribute to the capacity during charge and discharge. By satisfying the L3 / L1 ratio, the size of the first conductive material region 2111 covered by the first layer 50 in the second direction D2 is reduced. This means that the amount of active material covered by the first layer 50, which is less likely to contribute to the capacity, is reduced, thereby reducing the impact of the first layer 50 on the capacity of the electrochemical device 100.

[0101] In some embodiments, L1 ranges from 10 mm to 50 mm. When L1 is large, the first conductive material layer 211 covered by the first layer 50 in the second direction D2 is relatively large, thereby increasing the impact on the capacity of the electrochemical device 100. When L1 is small, the first region 2100 is also small in the second direction D2, and thus the distance J3 between the third side 3103 and the seventh side 2103 is also small. As a result, the heat dissipation coefficient K of the first region 2100 is reduced, and the heat dissipation capacity is relatively reduced.

[0102] like Figure 6 and Figure 7 As shown, in some embodiments, in the second direction D2 , the edge 52 of the first layer 50 may exceed the edge of the first pole piece 21 .

[0103] like Figure 4 As shown, in some embodiments, the second conductive material layer 212 includes a second conductive material region 2121, which encloses a second recess 2120. The electrochemical device 100 also includes a second layer 60, which comprises an insulating material. The second layer 60 covers the second region 2105 and adheres to the second conductive material region 2121. That is, in the first direction D1, the projection of the second region 2105 is located within the projection of the second layer 60. The second layer 60 can be used to compensate for the reduced thickness of the second conductive material layer 212 at that location due to the provision of the second recess 2120. In some embodiments, the second layer 60 can be a single-sided adhesive tape, a double-sided adhesive tape, or a ceramic coating.

[0104] like Figure 6 As shown, in some embodiments, in the second direction D2 , the edge 61 of the second layer 60 may exceed the edge of the first pole piece 21 .

[0105] like Figure 4As shown, in some embodiments, the electrochemical device 100 may further include a third layer 70 and a fourth layer 80, both comprising insulating materials. In the first direction D1, the first layer 50 is disposed between the first conductive plate 30 and the third layer 70, and the second layer 60 is disposed between the first conductive plate 30 and the fourth layer 80. The third layer 70 and the fourth layer 80 can further compensate for the reduced thickness of the electrode at the first recess 2110 and the second recess 2120. Furthermore, if a burr or weld mark in the connection region 311 pierces the separator 23, the third layer 70 can cover the burr or weld mark, further reducing the risk of a short circuit. When the first electrode sheet 21 is a positive electrode sheet and the second electrode sheet 22 is a negative electrode sheet, in the first direction D1, the projection of the third layer 70 is located within the projection of the first layer 50 (i.e., in the third direction D1, the end of the third layer 70 does not extend beyond the end of the first layer 50). This allows lithium ions released from the portion of the first conductive material layer 211 surrounding the first layer 50 in the first direction D1 to be fully received by the third conductive material layer 221, reducing the risk of excessive lithium ion accumulation and the generation of lithium dendrites, thereby improving safety. Similarly, in the first direction D1, the projection of the fourth layer 80 is located within the projection of the second layer 60 (i.e., in the third direction D1, the end of the third layer 70 does not extend beyond the end of the first layer 50). This allows lithium ions released from the portion of the second conductive material layer 212 surrounding the second layer 60 in the first direction D1 to be fully received by the fourth conductive material layer 222, reducing the risk of excessive lithium ion accumulation and the generation of lithium dendrites, thereby improving safety. In some embodiments, the third layer 70 and the fourth layer 80 may be single-sided tape, double-sided tape, or ceramic coating.

[0106] In other embodiments, when the first electrode 21 is a negative electrode and the second electrode 22 is a positive electrode, the third layer 70 can also be used to prevent lithium ions released from a portion of the third conductive material layer 221 corresponding to the third layer 70 in the first direction D1 from moving toward the second recess 2120, thereby reducing the risk of excessive lithium ion accumulation and the generation of lithium dendrites due to a lack of lithium ions capable of being embedded in the second recess 2120. Similarly, the fourth layer 80 can also be used to prevent lithium ions released from a portion of the fourth conductive material layer 222 corresponding to the fourth layer 80 in the first direction D1 from moving toward the first recess 2110, thereby reducing the risk of excessive lithium ion accumulation and the generation of lithium dendrites due to a lack of lithium ions capable of being embedded in the first recess 2110.

[0107] like Figure 4As shown, in some specific embodiments, the third layer 70 can be bonded to the third conductive material layer 221 of the second electrode 22, and the fourth layer 80 can be bonded to the fourth conductive material layer 222 of the second electrode 22, thereby fixing the third layer 70 and the fourth layer 80 in the electrochemical device 100 and compensating for thickness or reducing the risk of lithium dendrite formation. Of course, in other embodiments, the third layer 70 and the fourth layer 80 can also be bonded to the isolation film 23.

[0108] like Figure 5 As shown, in some embodiments, the second electrode 22 may also adopt a design similar to that of the first electrode 21, that is, the second conductive plate 40 is connected to the blank area of the second electrode 22 and the heat dissipation coefficient of the blank area is limited to be greater than or equal to 30%, thereby further improving the safety and reliability of the electrochemical device 100.

[0109] like Figures 3A to 5 As shown, in some embodiments, when the first segment 201 and the second segment 203 are straight segments, the first conductive plate 30 and the second conductive plate 40 can both be located in the first segment 201 , thereby improving the flatness of the first conductive plate 30 when connected to the first region 2100 .

[0110] Please refer to Figure 9 and Figure 10A , another embodiment of the present application also provides an electrochemical device 200. The difference from the electrochemical device 100 is at least that the third end edge 2104 of the first area 2100 in the second direction D2 (that is, the edge of the first area 2100 opposite to the seventh side 2103) is provided inwardly with a third recess R. The third recess R includes a first side edge R1, a second side edge R2 and a bottom edge R3. In the third direction D3, the first side edge R1 and the second side edge R2 face each other. When viewed from the first direction D1, the first side edge R1 and the second side edge R2 are both connected to the first end edge 211a of the first conductive material layer 211. The two ends of the bottom edge R3 are respectively connected to the first side edge R1 and the second side edge R2. When viewed from the first direction D1, the first side edge R1 has a slope edge R away from the first end edge 211a of the first conductive material layer 211. 11 , slope edge R 11 The second side R2 has a slope edge R3 away from the first end edge 211a of the first conductive material layer 211. 21 , slope edge R 21 Connecting the bottom edge R3. When viewed in the first direction D1, the bottom edge R3 at least partially overlaps with the fourth side 3104 of the third region 31. In some embodiments, in the third direction D3, the third recess R can be located approximately in the middle of the first region 2100, and the corners of the third recess R can be curved. That is, the bottom edge R3 is a straight line; the first side edge R1 is close to the sloped edge R3 of the bottom edge R3. 11 is an arc, and the rest is a straight line; the slope edge R of the second side R221 In other embodiments, the shape of the third notch R can also be changed when viewed from the first direction D1. Figure 10C As shown, the bottom edge R3 is an arc. 11 The slope edge R of the second side R2 is an arc, and the rest is a straight line. 21 is an arc, and the rest are straight lines. Figure 10D As shown, the corners of the third recess R may be right angles, in which case the bottom edge R3, the first side edge R1 and the second side edge R2 are all straight lines.

[0111] The first conductive material region 2111 includes a first extension region 2112 and a second extension region 2113 extending in the third direction D3 toward the third recess R. When viewed from the first direction D1, the first extension region 2112 and the second extension region 2113 are disposed on both sides of the third recess R and connect the third recess R. When viewed from the first direction D1, the first extension region 2112 is connected between the fifth side 2101 and the first side R1 of the third recess R, and the second extension region 2113 is connected between the sixth side 2102 and the second side R2 of the third recess R. In other embodiments, such as Figure 10B As shown, when viewed from the first direction D1, the first extension region 2112 and the second extension region 2113 can also be separated from the third recess R in the third direction D3. By providing the first extension region 2112 and the second extension region 2113, the thickness reduction at this location caused by the provision of the first recess 2110 in the first conductive material layer 211 can be compensated, thereby making the overall thickness of the electrochemical device 100 more uniform. Furthermore, when the first layer 50 is provided, the presence of the first extension region 2112 and the second extension region 2113 can also increase the contact area between the first layer 50 and the first conductive material layer 211, reducing the risk of wrinkles in the first layer 50. In addition, the preparation process of the electrode generally includes processes such as stirring the positive and negative electrode slurries, electrode coating, electrode rolling, and electrode stripping. In this application, since the third recess R is provided in the first area 2100 and the first conductive material area 2111 extends toward the third recess R to form the first extension area 2112 and the second extension area 2113, when the electrode is divided into strips (cutting the electrode along the third direction D3), the electrode thickness at the cut is uniform, which helps to reduce the risk of wavy edges at the cut of the electrode. Figure 9 and Figure 10A The first extension region 2112 and the second extension region 2113 are shown as being filled differently than other regions of the first conductive material layer 211. However, it should be understood that this does not mean that the first extension region 2112 and the second extension region 2113 are made of different active materials than other regions of the first conductive material layer 211, and there is no clear boundary between the two.

[0112] Furthermore, the size of the first extension area 2112 in the third direction D3 is defined as W1, the size of the second extension area 2113 in the third direction D3 is defined as W2, and (W1+W2) / T1≥20%. Among them, (W1+W2) / T1 can reflect the size ratio of the third recess R in the third direction D3. The larger (W1+W2) / T1 is, the smaller the size ratio of the third recess R is. Therefore, by limiting the ratio of (W1+W2) / T1, the situation in which the area available for heat dissipation in the first area 2100 is reduced due to the provision of the third recess R can be improved. Figure 9 and Figure 10A As shown, in some embodiments, since the third recess R is located approximately in the middle of the first region 2100 in the third direction D3, W1 is also approximately equal to W2. In other embodiments, the third recess R may also be biased toward one side of the first region 2100.

[0113] Since the first conductive material region 2111 of this embodiment also includes a first extension region 2112 and a second extension region 2113, if the size of the first conductive material region 2111 covered by the first layer 50 needs to be limited, in some embodiments, in addition to defining the distance between the third end edge 2104 of the first region 2100 and the eighth edge 51 in the second direction D2 as L1, and the distance between the seventh edge 2103 and the eighth edge 51 as L3, the sizes of the first extension region 2112 and the second extension region 2113 covered by the first layer 50 may also be further limited. Therefore, the sizes of the first extension region 2112 and the second extension region 2113 in the second direction D2 are further defined as being the same, L2, and (L2 + L3) / L1 is set to ≤ 30%. By defining (L2 + L3) / L1, the size of the first conductive material region 2111 covered by the first layer 50 in the second direction D2 is reduced. This means that the amount of active material covered by the first layer 50 that cannot contribute to the capacity is reduced, thereby reducing the impact of the first layer 50 on the capacity of the electrochemical device 200.

[0114] like Figure 10E As shown, in another embodiment, the first extension area 2112 and the second extension area 2113 have different sizes in the second direction D2. Specifically, the size of the first extension area 2112 in the second direction D2 is L2, and the size of the second extension area 2113 in the second direction D2 is L2'. In this case, it can be defined as (0.5L2+0.5L2'+L3) / L1≤30%. Figure 9 and Figure 10AAs shown, in some embodiments, defined in the third direction D3, the distance between the first extension area 2112 and the first conductive plate 30 is W3, and the distance between the second extension area 2113 and the first conductive plate 30 is W4, W1>W3, W2>W4. In this way, the size of the third recess R in the third direction D3 can also be reduced, thereby improving the situation where the area available for heat dissipation in the first area 2100 is reduced due to the provision of the third recess R. Figure 9 and Figure 10A As shown, in some embodiments, W1 is approximately equal to W2, and W3 is approximately equal to W4.

[0115] like Figure 9 and Figure 10A As shown, in some embodiments, in the third direction D3, the first extension region 2112 includes a ninth side 2114, and the second extension region 2113 includes a tenth side 2115. The ninth side 2114 is the inner edge of the first extension region 2112, with its two ends connecting the first side R1 and the fifth side 2101. The tenth side 2115 is the inner edge of the second extension region 2113, with its two ends connecting the second side R2 and the sixth side 2102, respectively. That is, when viewed from the first direction D1, the first region 2100 connects the ninth side 2114 and the tenth side 2115. The ninth side 2114 and the tenth side 2115 are straight lines.

[0116] like Figure 11 and Figure 12 As shown, in other embodiments, the ninth side 2114 and the tenth side 2115 may also be arc-shaped, convex away from the first region 2100. In this case, one end of the ninth side 2114 is connected to the first side edge R1. Compared to the embodiment shown in FIG10 , the other end of the ninth side 2114 connected to the fifth side 2101 can be moved downward in the opposite direction of the second direction D2. At the same time, the area between the two ends of the ninth side 2114 convex away from the first region 2100, resulting in the ninth side 2114 being arc-shaped. Similarly, one end of the tenth side 2115 is connected to the second side edge R2. Compared to the embodiment shown in FIG10 , the other end of the tenth side 2115 connected to the sixth side 2102 can be moved downward in the opposite direction of the second direction D2. At the same time, the area between the two ends of the tenth side 2115 convex away from the first region 2100, resulting in the tenth side 2115 being arc-shaped.

[0117] In some embodiments, in the second direction D2, the dimensions of both the first extension region 2112 and the second extension region 2113 are L2, and the distance between the ninth side 2114 and the fourth side 3104 is L4, where L2 < L4. Here, L4 represents the distance between the end of the ninth side 2114 connecting to the first side R1 and the fourth side 3104. L4 can reflect the length of the first region 2100 exposed from the side of the fourth side 3104 of the first conductive plate 30. By defining L2 < L4, that is, L4 is relatively large, it is beneficial to further increase the heat dissipation area of the first conductive plate 30, thereby reducing the temperature rise during high-current charging.

[0118] Please refer to Figure 13 , another embodiment of the present application further provides an electrochemical device 300. The difference from the electrochemical device 200 is that in the third direction D3, the first conductive plate 30 deviates from the middle position of the first region 2100. At this time, W3 < W4. In some embodiments, W3 < W1. In some embodiments, W2 < W4.

[0119] Among them, the electrochemical device 100 (or electrochemical devices 200, 300) of the present application includes all devices capable of undergoing electrochemical reactions. Specifically, the electrochemical device 100 includes all types of primary batteries, secondary batteries, fuel cells, solar cells, and capacitors (such as supercapacitors). Optionally, the electrochemical device 100 can be a lithium secondary battery, including lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, and lithium-ion polymer secondary batteries.

[0120] Please refer to Figure 14 , an embodiment of the present application further provides an electronic device 1, and the electronic device 1 includes an electrochemical device 100 (or electrochemical devices 200, 300).

[0121] Among them, the electrochemical device 100 of the present application is applicable to electronic devices 1 in various fields. In one embodiment, the electronic device 1 of the present application can be, but is not limited to, laptop computers, pen-input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, liquid crystal TVs, portable cleaners, portable CD players, mini-discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, motorized bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and lithium-ion capacitors, etc.

[0122] The following will describe the present application in detail through specific examples and comparative examples. Among them, the present application will be described by taking the electrochemical device as a battery and combining specific test methods.

[0123] Examples 1-4 and Comparative Example 1

[0124] After the cold pressing process, laser cleaning is used to create a first recess in the first conductive material layer on the first electrode piece, exposing the first region within the first recess. No third recess is provided in the first region. Next, a first conductive plate is welded to the first region, with one weld point, the area of which is S2. The specific values of T1, T2, S1, S2, J1, J2, J3, and L3 / L1 are recorded in Table 1. Conventional designs can be used for the second electrode piece, isolation membrane, and electrolyte.

[0125] The first pole piece, separator, and second pole piece of Examples 1-4 and Comparative Example 1 were stacked and wound, placed in a housing, and then injected with electrolyte to produce a battery with a size of 5.2mm×65.4mm×82.5mm and a capacity of 5.0Ah. Then, each battery was fast charged. Specifically, the charging process included: (1) charging to 4.25V at a constant current of 2.0C, and discharging to 1.5C at a constant voltage; (2) standing for 5 minutes; (3) charging to 4.38V at a constant current of 1.5C, and discharging to 1.0C at a constant voltage; (4) standing for 5 minutes; (5) charging to 4.43V at a constant current of 1.0C, and discharging to 0.05C at a constant voltage; (6) standing for 5 minutes. Before charging, the temperature near the position of the first conductive plate was measured using a multi-channel thermometer as t1. After charging was completed, the temperature near the position of the first conductive plate was measured using a multi-channel thermometer as t2. The temperature rise Δt = t2-t1, and the results are recorded in Table 1. Another thing to note is that the battery charging current is generally referenced by the rate C, where C is the value corresponding to the battery capacity. For example, if the battery capacity is 5.0Ah, the corresponding 1C is 5.0A, and 2C is equal to 10.0A.

[0126] Table 1

[0127]

[0128] As can be seen from the data in Table 1, compared to Comparative Example 1, the batteries of Examples 1-4 have a smaller temperature rise after fast charging because they meet the heat dissipation coefficient K ≥ 30%. Furthermore, the larger the heat dissipation coefficient, the smaller the battery temperature rise. Meanwhile, while Examples 2-3 have the same heat dissipation coefficient, the ratio L3 / L1 is relatively small in Example 2, resulting in a relatively lower temperature rise.

[0129] Examples 5-11

[0130] The difference from Examples 1-4 is that the first zone in Examples 5-9 is provided with a third recess, and the specific values of T1, T2, S1, S2, J1, J2, J3, and (L2+L3) / L1 are also different, which are recorded in Table 2 respectively.

[0131] The difference from Example 5 is that the values of (L2+L3) / L1 of Examples 10-11 are different, which are recorded in Table 3 respectively.

[0132] The first electrode, separator, and second electrode of Examples 5-9 were stacked and wound, placed in a housing, and then injected with electrolyte to produce a battery with a size of 5.40 mm × 80.3 mm × 70.7 mm and a capacity of 5.2 Ah. Each battery was then fast charged. Specifically, the charging process included: (1) charging at a constant current of 2.0 C to 4.25 V, and discharging at a constant voltage of 1.5 C; (2) standing for 5 minutes; (3) charging at a constant current of 1.5 C to 4.38 V, and discharging at a constant voltage of 1.0 C; (4) standing for 5 minutes; (5) charging at a constant current of 1.0 C to 4.43 V, and discharging at a constant voltage of 0.05 C; (6) standing for 5 minutes. The temperature rise Δt near the position of the first conductive plate was measured before and after charging, and the results are recorded in Table 2.

[0133] Table 2

[0134]

[0135] From the data in Table 2, it can be seen that since the batteries of Examples 5-9 meet the heat dissipation coefficient K ≥ 30%, the batteries have a smaller temperature rise after fast charging, and the larger the heat dissipation coefficient, the smaller the battery temperature rise.

[0136] The first electrode, separator, and second electrode of Examples 5, 10-11 were stacked and wound, placed in a housing, and then injected with electrolyte to produce a battery with a size of 5.2 mm × 65.4 mm × 82.5 mm and a capacity of 5.0 Ah. Each battery was then fast charged. Specifically, the charging process included: (1) charging at a constant current of 2.0 C to 4.05 V, and discharging at a constant voltage of 1.6 C; (2) standing for 5 min; (3) charging at a constant current of 1.6 C to 4.25 V, and discharging at a constant voltage of 1.2 C; (4) standing for 5 min; (5) charging at a constant current of 1.2 C to 4.35 V, and discharging at a constant voltage of 0.8 C; (6) standing for 5 min; (7) charging at a constant current of 0.8 C to 4.45 V, and discharging at a constant voltage of 0.05 C; (8) standing for 5 min. The temperature rise Δt near the position of the first conductive plate was measured before and after charging, and the results are recorded in Table 3.

[0137] Table 3

[0138]

[0139] From the data in Table 3, it can be seen that the heat dissipation coefficients of Examples 5, 10-11 are the same. However, compared with Example 10, Examples 5 and 11 satisfy (L2+L3) / L1≤30%, so the temperature rise is relatively lower. In Example 5, the value of (L2+L3) / L1 is the smallest, so the temperature rise is also the smallest.

[0140] Examples 12-14

[0141] The difference from Example 5 is that the specific values of T1, T2, S1, S2, J1, J2, J3, (L2+L3) / L1, and (W1+W2) / T1 of Examples 12-14 are different and are recorded in Table 4 respectively.

[0142] The first electrode sheets, separators, and second electrode sheets of Examples 5, 12-14 were stacked and wound, placed in a housing, and then injected with electrolyte to produce batteries with dimensions of 3.77 mm × 62.0 mm × 141.0 mm and a capacity of 5.2 Ah. Each battery was then rapidly charged. Specifically, the charging process included: (1) charging at a constant current of 1.8 C to 4.2 V, and discharging at a constant voltage of 0.7 C; (2) allowing the battery to rest for 5 minutes; (3) charging at a constant current of 0.7 C to 4.4 V, and discharging at a constant voltage of 0.05 C; and (4) allowing the battery to rest for 5 minutes. The temperature rise Δt near the position of the first conductive plate was measured before and after charging, and the results are recorded in Table 4.

[0143] Table 4

[0144]

[0145] As can be seen from the data in Table 4, compared to Example 12, while the heat dissipation coefficient K and (L2+L3) / L1 values are the same in Example 5, the value of (W1+W2) / T1 is relatively larger, resulting in a lower temperature rise. Compared to Example 14, while the heat dissipation coefficient K and (L2+L3) / L1 values are the same in Example 13, the value of (W1+W2) / T1 is relatively larger, resulting in a lower temperature rise.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. An electrochemical device comprising an electrode assembly and a first conductive plate, wherein the electrode assembly is a wound structure and includes a first electrode sheet, wherein: The first pole piece includes a first conductive layer and a first conductive material layer, the first conductive layer includes a first surface and a second surface opposite to each other, the first conductive material layer is provided on the first surface, the first surface includes a first area, the first conductive material layer includes a first conductive material area, the first conductive material area is surrounded by a first recess, the first area is exposed in the first recess, and the first conductive plate is connected to the first area and extends out of the first pole piece; The first conductive plate includes a third region and a fourth region connected to each other, a direction perpendicular to the third region is defined as a first direction, in which a projection of the third region is located within a projection of the first region, and a projection of the fourth region is located outside a projection of the first region, the third region includes a connection region, and the first conductive plate is connected to the first region via the connection region; When viewed from the first direction, the third area includes a first side, a second side, a third side, and a fourth side, the first side and the second side are opposite, the third side and the fourth side are opposite, and the fourth side is connected to the fourth area; the first area includes a fifth side, a sixth side, and a seventh side; an extension direction of the third area is defined as a second direction, and in the second direction, the seventh side and the third side are arranged in sequence; in the third direction, the fifth side, the first side, the second side, and the sixth side are arranged in sequence, and the first direction, the second direction, and the third direction are perpendicular to each other; Define the size of the third area in the third direction as T1, the size of the third area in the second direction as T2, the area of the projection of the third area in the first direction as S1, the area of the projection of the connection area in the first direction as S2, the distance between the first side and the fifth side as J1, the distance between the second side and the sixth side as J2, and the distance between the third side and the seventh side as J3, then S2 / S1+(J1+J2+J3) / (T1+T2)≥30%; A third recess is provided at the edge of the first region in the second direction, and the first conductive material region includes a first extension region and a second extension region extending toward the third recess. When viewed from the first direction, the first extension region and the second extension region are provided on both sides of the third recess.

2. The electrochemical device according to claim 1, wherein The first pole piece also includes a second conductive material layer arranged on the second surface; the second surface includes a second area, the second conductive material layer includes a second conductive material area, the second conductive material area is surrounded to form a second recess, the second area is exposed in the second recess, and in the first direction, the projection of the first area and the projection of the second area at least partially overlap.

3. The electrochemical device according to claim 2, wherein The electrochemical device further includes a first layer bonded to the third region, the first layer comprising an insulating material, and in the first direction, a projection of the third region is located within a projection of the first layer.

4. The electrochemical device according to claim 3, wherein The first layer also adheres to the first conductive material area, and in the first direction, the projection of the first area is located within the projection of the first layer.

5. The electrochemical device according to claim 4, wherein The electrochemical device further includes a second layer comprising an insulating material, the second layer being bonded to the second conductive material region, and a projection of the second region being located within a projection of the second layer in the first direction.

6. The electrochemical device according to claim 4, wherein When viewed from the first direction, the first layer includes an eighth side, and in the second direction, the seventh side is provided between the eighth side and the third side; The distance between the edge of the first region in the second direction and the eighth side is defined as L1, and the distance between the seventh side and the eighth side is defined as L3, and L3 / L1≤30%.

7. The electrochemical device according to claim 4, wherein When viewed from the first direction, the first layer includes an eighth side, and in the second direction, the seventh side is provided between the eighth side and the third side; Define the distance between the edge of the first zone in the second direction and the eighth side as L1, the sizes of the first extension zone and the second extension zone in the second direction are the same and are both L2, the distance between the seventh side and the eighth side is L3, then (L2+L3) / L1≤30%.

8. The electrochemical device according to claim 1, wherein It is defined that the dimension of the first extension area in the third direction is W1, and the dimension of the second extension area in the third direction is W2, then (W1+W2) / T1≥20%.

9. The electrochemical device according to claim 1, wherein Define the size of the first extension area in the third direction as W1, the size of the second extension area in the third direction as W2, the distance between the first extension area and the first conductive plate in the third direction as W3, and the distance between the second extension area and the first conductive plate in the third direction as W4, then at least one of the following conditions is met: W3 <W1;W2<W4;W3<W4。 10. The electrochemical device according to claim 1, wherein In the third direction, the first extension area and the second extension area include a ninth side and a tenth side respectively, and the first area connects the ninth side and the tenth side; The ninth side and the tenth side are straight lines or arcs.

11. The electrochemical device according to claim 10, wherein In the second direction, the size of the first extension area and / or the second extension area is L2, and the distance between the ninth side and the fourth side is L4, then L2 <L4。 12. The electrochemical device according to claim 6 or 7, wherein: The range of L1 is 10mm to 50mm.

13. The electrochemical device according to claim 5, wherein The electrochemical device further includes a third layer and a fourth layer, both of which include insulating materials. In the first direction, the first layer is disposed between the first conductive plate and the third layer, and the second layer is disposed between the first conductive plate and the fourth layer.

14. The electrochemical device according to claim 13, wherein The electrode assembly further includes a second electrode sheet, and at least one of the third layer or the fourth layer is bonded to the second electrode sheet.

15. The electrochemical device according to claim 5, wherein In the second direction, an edge of at least one of the first layer or the second layer exceeds an edge of the first pole piece.

16. The electrochemical device according to claim 1, wherein The connection area is welded to the first area, and the connection area includes a plurality of welding points. The area S2 is the sum of the areas of projections of the plurality of welding points in the first direction.

17. The electrochemical device according to claim 1, wherein The electrode assembly also includes a second electrode sheet and an isolation membrane. The first electrode sheet, the isolation membrane and the second electrode sheet are stacked and wound to form the electrode assembly. In the winding direction, the electrode assembly includes a first section, a first bending section, a second section and a second bending section connected in sequence, and the first conductive plate is located in the first section.

18. The electrochemical device according to claim 1, wherein The electrochemical device further includes a shell, which includes a main body for accommodating the electrode assembly and a sealing edge connected to the main body. The sealing edge includes a polymer layer, and the fourth region extends out of the shell from the polymer layer.

19. An electronic device comprising the electrochemical device according to any one of claims 1 to 18.

Images