Electrochemical devices and electronic devices

Abstract

The present application proposes an electrochemical device and an electronic device, wherein the electrochemical device includes an electrode assembly, and the electrode assembly includes a first electrode sheet, a first diaphragm, and a second electrode sheet stacked in sequence. The first electrode sheet includes a first current collector, a first active material layer, and a first insulating layer, wherein the first active material layer is stacked on the first current collector, and the first insulating layer is stacked on the first surface of the first active material layer facing away from the first current collector; along the first direction, the first electrode sheet has a first end and a second end, at least one of the first end or the second end is connected to the first pole ear, and the first insulating layer is located at the first end; the width w1 of the first insulating layer satisfies: 2mm≤w1≤10mm. By arranging the first insulating layer on the surface of the first active layer and limiting the width of the first insulating layer, the risk of short circuit between the first electrode sheet and the second electrode sheet due to the contraction of the first diaphragm is reduced, and a good interface between the first electrode sheet and the first diaphragm can be maintained to meet the requirements for electrochemical performance.

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. Background Art

[0002] An electrochemical device is a device that converts external energy into electrical energy and stores it inside to power external electronic devices (such as portable electronic devices, etc.) when needed. At present, electrochemical devices are widely used in electronic devices such as drones, mobile phones, tablets, and laptops. In general, an electrochemical device includes an electrode assembly, and the electrode assembly includes a first pole piece, a first diaphragm, and a second pole piece. Among them, the first pole piece and the second pole piece have opposite polarities, and the first diaphragm is separated between the first pole piece and the second pole piece. At present, when the first diaphragm separated between the first pole piece and the second pole piece shrinks, it is easy for the first pole piece and the second pole piece to contact and short-circuit. Summary of the invention

[0003] The embodiments of the present application aim to provide an electrochemical device and an electronic device to solve the problem in the prior art that when the first diaphragm between the first pole piece and the second pole piece shrinks, the first pole piece and the second pole piece are easily in contact and short-circuited.

[0004] According to one aspect of an embodiment of the present application, an electrochemical device is provided, the electrochemical device comprising an electrode assembly. The electrode assembly comprises a first pole piece, a first diaphragm and a second pole piece stacked in sequence. The first pole piece comprises a first current collector, a first active material layer and a first insulating layer, the first active material layer is stacked on a surface of the first current collector, and the first insulating layer is stacked on the first surface of the first active material facing the back of the first current collector. Along the first direction, the first pole piece has a first end and a second end, at least one of the first end or the second end is connected to the first pole ear, and the first insulating layer is located at the first end. Along the first direction, the width w1 of the first insulating layer satisfies: 2mm≤w1≤10mm.

[0005] By setting the first insulating layer at the first end of the first pole piece and limiting the width of the first insulating layer to be no less than 2 mm, when the first diaphragm shrinks, the first insulating layer is spaced between the first pole piece and the second pole piece, reducing the risk of short circuit between the first pole piece and the second pole piece. In addition, by limiting the width of the first insulating layer to be no more than 10 mm, the influence of the setting of the first insulating layer on the interface performance of the first pole piece is reduced, and then the influence of the setting of the first insulating layer on the migration of lithium ions between the first pole piece and the second pole piece is reduced, and the overall performance of the electrochemical device is excellent.

[0006] In an optional manner, the first pole piece, the first diaphragm and the second pole piece are stacked in sequence along the second direction, and the first direction is perpendicular to the second direction. In some embodiments, the second direction is referred to as the thickness direction of the electrochemical device.

[0007] In an optional manner, the first electrode tab is connected to the first current collector, and the first electrode tab extends out of the first current collector along a first direction to facilitate connection of the electrochemical device with an external circuit.

[0008] In an optional manner, the first end and the second end are two opposite ends of the first pole piece in a direction in which the first pole ear extends out of the first current collector, that is, the first end and the second end are two opposite ends of the first pole piece along the first direction.

[0009] In an optional manner, along the first direction, the edge of the first current collector away from the second end is flush with the edge of the first active material layer away from the second end, that is, the first active material layer is provided on a surface of the first current collector facing the first diaphragm, and the first current collector is fully utilized, thereby improving the energy density of the electrochemical device.

[0010] In an optional manner, due to limitations of the processing technology for forming the first pole piece, the first current collector is arranged along the first direction away from the edge of the second end, beyond the edge of the first active material layer away from the second end, and the size of the exceeding part is not greater than 1 mm.

[0011] In an optional manner, the first surface includes a first region and a second region, the first region is located at the first end, the first insulating layer is stacked on the first region, and a surface of the first insulating layer facing away from the first region is flush with the second region, so that the interface of the first pole piece facing the first diaphragm is flat, thereby facilitating the migration of lithium ions between the first pole piece and the second pole piece. In an optional manner, the width w1 of the first insulating layer satisfies: 3mm≤w1≤5mm.

[0012] In an optional manner, the first pole piece further includes a second insulating layer, the second insulating layer is stacked on the first surface, and the second insulating layer is located at the second end. In an optional manner, along the first direction, a width w2 of the second insulating layer satisfies: 2mm≤w2≤10mm.

[0013] By setting a second insulating layer at the second end of the first pole piece and limiting the width of the second insulating layer to be no less than 2 mm, when the first diaphragm shrinks, the second insulating layer is spaced between the first pole piece and the second pole piece, reducing the risk of short circuit between the first pole piece and the second pole piece. In addition, by limiting the width of the second insulating layer to no more than 10 mm, the influence of the setting of the second insulating layer on the interface performance of the first pole piece can be reduced, and then the influence of the setting of the second insulating layer on the migration of lithium ions between the first pole piece and the second pole piece can be reduced, and the overall performance of the electrochemical device is excellent.

[0014] In an optional manner, the first surface further includes a third region, the third region is located at the second end, and a surface of the second insulating layer facing away from the third region is flush with the second region, so that the interface of the first pole piece facing the first diaphragm is flat, thereby facilitating the migration of lithium ions between the first pole piece and the second pole piece. In an optional manner, along the first direction, the width w2 of the second insulating layer satisfies: 3mm≤w2≤5mm.

[0015] In an optional manner, the first pole piece further includes a second active material layer, and the second active material layer is stacked on the other surface of the first current collector. The first pole piece further includes a third insulating layer, and the third insulating layer is stacked on the second surface of the second active material layer facing away from the first current collector, and the third insulating layer is located at the first end. In an optional manner, along the first direction, the width w3 of the third insulating layer satisfies: 2mm≤w3≤10mm. By setting the third insulating layer, the risk of internal short circuit of the electrode assembly is further reduced.

[0016] In an optional manner, along the first direction, the third insulating layer and the first insulating layer are arranged at the first end portion opposite to each other. In an optional manner, along the first direction, a width w3 of the third insulating layer satisfies: 3mm≤w3≤5mm.

[0017] In an optional manner, the first pole piece further includes a fourth insulating layer, the fourth insulating layer is stacked on the second surface, and the fourth insulating layer is located at the second end. In an optional manner, along the first direction, the width w4 of the fourth insulating layer satisfies: 2mm≤w4≤10mm. By providing the fourth insulating layer, the risk of internal short circuit of the electrode assembly is further reduced.

[0018] In an optional manner, along the first direction, the fourth insulating layer and the second insulating layer are arranged opposite to each other at the second end. In an optional manner, along the first direction, the width w4 of the fourth insulating layer satisfies: 3mm≤w4≤5mm.

[0019] In an optional manner, the first pole piece further includes a first layer, and the first layer is stacked between the first current collector and the first active material layer. The first layer bonds the first current collector and the first active material layer, thereby reducing the risk of the first active material layer falling off from the first current collector, reducing the first insulating layer and the second insulating layer disposed on the first active material layer, and the risk of the first active material layer falling off from the first current collector at the same time, so that when the first diaphragm shrinks, there is a first insulating layer and / or a second insulating layer between the first pole piece and the second pole piece. In an optional manner, the first layer includes a binder and a conductive agent.

[0020] In an optional manner, the first pole piece, the first diaphragm and the second pole piece are wound together into a winding structure, and the winding center axis of the winding structure is arranged along the first direction. The outermost circle of the first pole piece is closer to the winding center axis than the outermost circle of the second pole piece. The first insulating layer extends from the winding end of the first pole piece toward the winding start end of the first pole piece, and the first insulating layer is arranged around the outermost circle of the first pole piece away from the winding center axis. When the electrochemical device is damaged due to falling or other reasons, the outermost circle of the first diaphragm shrinks severely at the first end or the second end, the first insulating layer is located at the first end, the first insulating layer extends from the winding end of the first pole piece toward the winding start end of the first pole piece, and the first insulating layer is arranged around the outermost circle of the first pole piece, then the first insulating layer acts as a spacing between the first pole piece and the second pole piece, reducing the risk of short circuit between the first pole piece and the second pole piece due to the shrinkage of the first diaphragm.

[0021] In an optional manner, the first insulating layer extends from the winding end of the first pole piece to the winding starting end of the first pole piece, thereby strengthening the spacing effect of the first insulating layer on the first pole piece and the second pole piece.

[0022] In an optional manner, the electrode assembly further includes a second diaphragm, a third pole piece, a third diaphragm and a fourth pole piece stacked in sequence, the second diaphragm is stacked on the first pole piece, and the second diaphragm is spaced between the first pole piece and the third pole piece. The number of the second diaphragm, the third pole piece, the third diaphragm and the fourth pole piece is multiple groups, and the multiple groups of the second diaphragm, the third pole piece, the third diaphragm and the fourth pole piece are stacked along the second direction, thereby increasing the external charging and discharging capability of the electrochemical device.

[0023] According to one aspect of an embodiment of the present application, there is provided an electronic device, comprising a load and any one of the above electrochemical devices, wherein the electrochemical device supplies power to the load.

[0024] The beneficial effects of the embodiments of the present application include that by setting the first insulating layer at the first end of the first pole piece and limiting the width of the first insulating layer to be no less than 2 mm, when the first diaphragm shrinks, the first insulating layer is spaced between the first pole piece and the second pole piece, reducing the risk of short circuit between the first pole piece and the second pole piece. In addition, by limiting the width of the first insulating layer to be no more than 10 mm, the influence of the setting of the first insulating layer on the interface performance of the first pole piece is reduced, and then the influence of the setting of the first insulating layer on the migration of lithium ions between the first pole piece and the second pole piece is reduced, and the overall performance of the electrochemical device is excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0026] Figure 1 is a three-dimensional schematic diagram of an electrochemical device provided in an embodiment of the present application;

[0027] Figure 2 The embodiment of the present application provides Figure 1 A cross-sectional view of the AA line;

[0028] Figure 3 The embodiment of the present application provides Figure 1 A cross-sectional view of the middle BB line;

[0029] Figure 4 The embodiment of the present application provides Figure 1 A cross-sectional view of the mid-CC line;

[0030] Figure 5 The embodiment of this application provides Figure 2 Enlarged view of the middle D1 section;

[0031] Figure 6 The embodiment of the present application provides Figure 1 Another cross-sectional view of the middle BB line;

[0032] Figure 7 The embodiment of the present application provides Figure 1 Another cross-sectional view of the AA line;

[0033] Figure 8 The embodiment of this application provides Figure 7 Enlarged view of the middle D2 section;

[0034] Fig. 9 The embodiment of the present application provides Figure 1 Another cross-sectional view of the mid-CC line;

[0035] Fig.10 The embodiment of the present application provides Figure 1 Another cross-sectional view of the AA line;

[0036] Fig.11 The embodiment of the present application provides Figure 1 Another cross-sectional view of the AA line;

[0037] Fig.12 The embodiment of this application provides Fig.11 Enlarged view of the middle D3 section;

[0038] Fig.13 The embodiment of this application provides Fig.11 A magnified view of the middle D4 section;

[0039] Fig.14 The embodiment of the present application provides Figure 1 Another cross-sectional view of the middle BB line;

[0040] Fig.15 The embodiment of the present application provides Figure 1 Another cross-sectional view of the middle BB line;

[0041] Fig.16 The embodiment of the present application provides Figure 1 Another cross-sectional view of the middle AA line;

[0042] Fig.17 The embodiment of the present application provides Figure 1 Two more cross-sectional views along line AA. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field belong to the scope of protection of this application.

[0044] It should be noted that when an element is described as being "fixed to" another element, it may be directly on the other element, or one or more elements may be located therebetween. When an element is described as being "connected to" another element, it may be directly connected to the other element, or one or more elements may be located therebetween. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this specification are for illustrative purposes only.

[0045] In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0046] See also Figure 1 and Figure 2 , Figure 1 It is a three-dimensional schematic diagram of the electrochemical device provided in the embodiment of the present application. Figure 2 The embodiment of the present application provides Figure 1 A cross-sectional view along line AA in FIG. 1 . The electrochemical device 100 includes an electrode assembly 1 , which is a charge-discharge element in the electrochemical device 100 .

[0047] In some embodiments, the electrochemical device 100 further includes a packaging case 2, a first pole tab 3 and a second pole tab 4, and the electrode assembly 1 is accommodated in the packaging case 2. The first pole tab 3 and the second pole tab 4 are respectively connected to the electrode assembly 1, and the first pole tab 3 and the second pole tab 4 are respectively extended from the packaging case 2 to realize power supply to an external electronic device and to charge the electrode assembly 1 when the energy of the electrode assembly 1 is insufficient.

[0048] For the electrode assembly 1 above, see Figure 2 , Figure 2 1 shows a partial structure of the electrode assembly 1. The electrode assembly 1 includes a first pole piece 11, a first diaphragm 12, and a second pole piece 13. The first pole piece 11, the first diaphragm 12, and the second pole piece 13 are stacked in sequence. The first pole piece 11, the first diaphragm 12, and the second pole piece 13 are stacked in sequence along the second direction L2. The second direction L2 is the thickness direction of the electrochemical device 100.

[0049] In some embodiments, when the first electrode sheet 11, the first separator 12 and the second electrode sheet 13 are only stacked in sequence but not wound, the electrode assembly 1 is a laminated structure, such as Figure 2 As shown, at this time, Figure 1 The electrode assembly 1 in the electrochemical device 100 is a laminate structure.

[0050] In some embodiments, when the first electrode sheet 11, the first separator 12 and the second electrode sheet 13 are stacked and wound in sequence, the electrode assembly 1 forms a winding structure, such as Figure 3 As shown, Figure 3 The embodiment of the present application provides Figure 1 A cross-sectional view of the BB line. At this time, Figure 1 The electrode assembly 1 in the electrochemical device 100 is a wound structure.

[0051] For the first pole piece 11, no matter the electrode assembly 1 is a laminated structure or a wound structure, the following structure and function of the first pole piece 11 are applicable. Figure 4 , Figure 4 The embodiment of the present application provides Figure 1A cross-sectional view along the CC line in FIG. Along the first direction L1, the first pole sheet 11 has a first end 111s and a second end 112s. Among them, the first direction L1 is the extension direction of the first pole tab 3 or the second pole tab 4, and the first direction L1 is perpendicular to the second direction L2. In some embodiments, the first direction L1 can be the length direction of the electrochemical device 100. The first pole tab 3 is connected to the first end 111s, and the first pole tab 3 extends the first end 111s along the first direction L1. Alternatively, the first pole tab 3 is connected to the second end 112s, and the first pole tab 3 extends the second end 112s along the first direction L1. That is, the first end 111s and the second end 112s are two opposite ends of the first pole sheet 11 along the direction in which the first pole tab 3 extends out of the first current collector 111, that is, the first end 111s and the second end 112s are two opposite ends of the first pole sheet 11 along the first direction L1.

[0052] See also Figure 2 or Figure 3 The first electrode sheet 11 includes a first current collector 111 , a first active material layer 112 and a first insulating layer 113 .

[0053] The first active material layer 112 is stacked on a surface of the first current collector 111 facing the first separator 12 .

[0054] Among them, see Figure 4 , the first current collector 111 is connected to the first pole tab 3 of the electrochemical device 100. In some embodiments, the first pole tab 3 is connected to the first current collector 111, and the first pole tab 3 extends out of the first current collector 111 along the first direction L1, so as to facilitate the connection of the electrochemical device 100 with an external circuit. The first pole tab 3 is connected to the first current collector 111, and the first current collector 111 is electrically connected to the external circuit. In some embodiments, the connection method of the first pole tab 3 and the first current collector 111 can be welding or conductive adhesive connection. In some embodiments, the first pole tab 3 and the first current collector 111 can be an integrated structure, that is, the first pole tab 3 extends from the first current collector 111.

[0055] Among them, see Figure 2 or Figure 3 The first insulating layer 113 is stacked on the first surface 1121 of the first active material layer 112 facing the first diaphragm 12, and the first insulating layer 113 is located at the first end 111s. Figure 5 , Figure 5 The embodiment of this application provides Figure 2 The enlarged view of the D1 portion in the middle. Along the first direction L1, the width w1 of the first insulating layer 113 satisfies: 2mm≤w1≤10mm, Figure 5The first insulating layer 113 is entirely superimposed on the first active material layer 112, that is, the width w1 of the first insulating layer 113 and the first active material layer 112 satisfies: 2mm≤w1≤10mm. In some embodiments, along the first direction L1, the width w1 of the first insulating layer 113 satisfies: 3mm≤w1≤5mm, that is, the width w1 of the first insulating layer 113 and the first active material layer 112 satisfies 3mm≤w1≤5mm. By providing the first insulating layer 113 at the first end 111s of the first pole piece 11, and limiting the width of the first insulating layer 113 to not less than 2mm, when the first diaphragm 12 shrinks at the first end 111s, the first insulating layer 113 is spaced between the first pole piece 11 and the second pole piece 13, thereby reducing the risk of short circuit between the first pole piece 11 and the second pole piece 13. In addition, by limiting the width of the first insulating layer 113 to no more than 10 mm, the influence of the setting of the first insulating layer 113 on the interface performance of the first pole piece 11 is reduced, thereby reducing the influence of the setting of the first insulating layer 113 on the migration of lithium ions between the first pole piece 11 and the second pole piece 13, and the overall performance of the electrochemical device 100 is excellent.

[0056] It should be noted that, in the first direction L1, the first insulating layer 113 extends from the edge of the first pole piece 11 away from the second end 112s to the second end 112s. The dimension of the first insulating layer 113 extending from the edge of the first pole piece 11 away from the second end 112s to the second end 112s is the width w1 of the first insulating layer 113.

[0057] In some embodiments, along the first direction L1, the edge of the first current collector 111 away from the second end 112s is flush with the edge of the first active material layer 112 away from the second end 112s, or the edge of the first current collector 111 away from the second end 112s exceeds the edge of the first active material layer 112 away from the second end 112s by no more than 1 mm. Since the width w1 of the first insulating layer 113 is not less than 2 mm, the first insulating layer 113 is at least partially located in the first active material layer 112. That is, along the first direction L1, when the edge of the first current collector 111 away from the second end 112s is flush with the edge of the first active material layer 112 away from the second end 112s, the first insulating layer 113 is entirely located in the first active material layer 112; along the first direction L1, when the size of the edge of the first current collector 111 away from the second end 112s and the portion exceeding the edge of the first active material layer 112 away from the second end 112s is not greater than 1 mm, a portion of the first insulating layer 113 is located in the first active material layer 112, and another portion of the first insulating layer 113 is located in the exposed first current collector 111. By limiting the width of the first insulating layer 113 to be not less than 2 mm, along the first direction L1, regardless of whether the edge of the first current collector 111 away from the second end 112s exceeds the edge of the first active material layer 112 away from the second end 112s, the provision of the first insulating layer 113 can reduce the risk of short circuit between the first active material layer 112 and the second electrode sheet 13, thereby reducing the risk of short circuit between the first electrode sheet 11 and the second electrode sheet 13.

[0058] It is worth noting that the structure and function of the second end portion 112s may refer to the first end portion 111s, and will not be described in detail here.

[0059] In some embodiments, the first insulating layer 113 includes an inorganic material. In some embodiments, the inorganic material includes a ceramic material. In some embodiments, the ceramic material includes at least one of titanium dioxide, aluminum oxide, boehmite, zirconium oxide, lithium fluoride, silicon oxide, calcium oxide, magnesium oxide, tantalum oxide, silicon nitride, cubic boron nitride, aluminum nitride, chromium nitride, titanium nitride, silicon carbide, boron carbide, titanium carbide, and chromium carbide.

[0060] It is worth noting that the above definition of the first insulating layer 113 is also applicable to the electrode assembly 1 with a laminate structure or the electrode assembly 1 with a wound structure.

[0061] When the electrode assembly 1 is a laminated structure, in some embodiments, refer to Figure 4, along the third direction L3, the first insulating layer 113 extends from the third end 113s of the first pole piece 11 to the fourth end 114s. The third direction L3 is perpendicular to the first direction L1, and the third direction L3 is perpendicular to the second direction L2. In some embodiments, the third direction L3 is referred to as the width direction of the electrochemical device 100. The third end 113s and the fourth end 114s are two ends of the first pole piece 11 that are oppositely arranged along the third direction L3. When the first pole piece 11 is observed along the second direction L2 and the first pole piece 11 is rectangular, the first end 111s, the third end 113s, the second end 112s and the fourth end 114s are connected in sequence, or the first end 111s, the fourth end 114s, the second end 112s and the third end 113s are connected in sequence.

[0062] When the electrode assembly 1 is a wound structure, in some embodiments, refer to Figure 3 , along the direction opposite to the winding direction C2, the first insulating layer 113 extends from the winding end of the first pole piece 11 toward the winding start end of the first pole piece 11, and the first insulating layer 113 is arranged around the surface of the outermost circle of the first pole piece 11 that is away from the winding center axis C1. In some embodiments, the winding start end of the first pole piece 11 is located at the winding start end of the electrode assembly 1 of the winding structure, and the winding end end of the first pole piece 11 is located at the winding end end of the electrode assembly 1 of the winding structure.

[0063] In some other embodiments, see Figure 6 , Figure 6 The embodiment of the present application provides Figure 1 Another cross-sectional view of the BB line. At this time, Figure 1 The electrode assembly 1 in the electrochemical device 100 is a winding structure. In the direction opposite to the winding direction C2, the first insulating layer 113 extends from the winding end of the first pole piece 11 to the winding start end of the first pole piece 11. It is worth noting that, in some embodiments, the winding start end of the first pole piece 11 is provided with a first pole lug 3, and in the direction opposite to the winding direction C2, the first insulating layer 113 extends from the winding end of the first pole piece 11 to the first pole lug 3.

[0064] It is worth noting that the electrode assembly 1 is a winding structure. In some embodiments, the outermost circle of the first pole piece 11 is closer to the winding center axis C1 than the outermost circle of the second pole piece 13. When the electrochemical device 100 is impacted due to falling or other reasons, the outermost circle of the first diaphragm 12 shrinks severely at the first end 111s or the second end 112s. The first insulating layer 113 is located at the first end 111s. The first insulating layer 113 extends from the winding end of the first pole piece 11 toward the winding start end of the first pole piece 11. The first insulating layer 113 is arranged around the outermost circle of the first pole piece 11. The first insulating layer 113 acts as a spacing between the first pole piece 11 and the second pole piece 13, reducing the risk of short circuit between the first pole piece 11 and the second pole piece 13 due to the contraction of the first diaphragm 12. Among them, the outermost circle of the first diaphragm 12 is the circle of the first diaphragm 12 farthest from the winding center axis C1 in the winding structure.

[0065] In the present application, one circle refers to a point on the wound battery cell as the starting end, and one circle along the winding direction to another point as the ending end. The ending end is in a straight line with the starting end and the center of the circle, and the starting end is between the ending end and the center of the circle. Half a circle is half of the above-mentioned one circle.

[0066] In some embodiments, see Figure 5 The first surface 1121 of the first active material layer 112 facing the first diaphragm 12 includes a first region 1121a and a second region 1121b, the first region 1121a is located at the first end 111s, the first insulating layer 113 is superimposed on the first region 1121a, and a surface of the first insulating layer 113 facing away from the first region 1121a is flush with the second region 1121b, so that the interface of the first electrode 11 close to the first diaphragm 12 is smooth, which is beneficial to the migration of lithium ions between the first electrode 11 and the second electrode 12.

[0067] It is worth noting that, in some embodiments, the first region 1121 a is formed by the first surface 1121 being recessed toward the first current collector 111 .

[0068] It is worth noting that, in some embodiments, the preparation method of the first pole piece 11 is to coat the first active material on the first current collector 111 to form a first active material layer 112, and then stack the first insulating layer 113 on the first area 1121a, and then extrude the product through a roller to form a first pole piece 11 with a smooth interface.

[0069] It should be understood that the flatness described in the present application refers to that a surface of the first insulating layer 113 facing away from the first region 1121a forms a relatively flat interface with the surface of the second region 1121b. It can be understood that the part with the first insulating layer 113 and the part without the first insulating layer 113 show that the thickness of the material layer arranged on the first current collector 111 is relatively uniform.

[0070] In some embodiments, see Figure 7 and Figure 8 , Figure 7 The embodiment of the present application provides Figure 1 Another cross-sectional view of the AA line, Figure 8 The embodiment of this application provides Figure 7 The first electrode 11 includes, in addition to the first current collector 111, the first active material layer 112 and the first insulating layer 113, a second insulating layer 114, which is disposed at the second end 112s of the first electrode 11. The second insulating layer 114 is superimposed on the first surface 1121, and the second insulating layer 114 is located at the second end 112s. Along the first direction L1, the width w2 of the second insulating layer 114 satisfies: 2mm≤w2≤10mm, Figure 8 The second insulating layer 114 is entirely superimposed on the first surface 1121 of the first active material layer 112, that is, the width w2 of the second insulating layer 114 and the first active material layer 112 satisfies: 2mm≤w2≤10mm. In some embodiments, along the first direction L1, the width w2 of the second insulating layer 114 satisfies: 3mm≤w2≤5mm, that is, the width w2 of the second insulating layer 114 and the first active material layer 112 satisfies: 3mm≤w2≤5mm. By providing the second insulating layer 114 at the second end 112s of the first electrode sheet 11, and limiting the width of the second insulating layer 114 to be not less than 2mm, when the first diaphragm 12 shrinks at the second end 112s, the second insulating layer 114 is spaced between the first electrode sheet 11 and the second electrode sheet 13, thereby reducing the risk of short circuit between the first electrode sheet 11 and the second electrode sheet 13. In addition, by limiting the width of the second insulating layer 114 to no more than 10 mm, the influence of the second insulating layer 114 on the interface performance of the first pole piece 11 is reduced, thereby reducing the influence of the second insulating layer 114 on the migration of lithium ions between the first pole piece 11 and the second pole piece 13, and the overall performance of the electrochemical device 100 is excellent.

[0071] It is worth noting that the above definition of the second insulating layer 114 is also applicable to the electrode assembly 1 with a laminate structure or the electrode assembly 1 with a wound structure.

[0072] When the electrode assembly 1 is a laminated structure, please refer to Fig. 9 , Fig. 9The embodiment of the present application provides Figure 1 Another cross-sectional view of the CC line. In some embodiments, along the third direction L3, the second insulating layer 114 extends from the third end 113s to the fourth end 114s of the first pole piece 11.

[0073] When the electrode assembly 1 is a winding structure, in some embodiments, the second insulating layer 114 extends from the winding end of the first pole piece 11 toward the winding starting end of the first pole piece 11 along the direction opposite to the winding direction C2, and the second insulating layer 114 is arranged around the outermost circle of the first pole piece 11 away from the winding center axis C1.

[0074] In other embodiments, along the direction opposite to the winding direction C2, the second insulating layer 114 extends from the winding end of the first pole piece 11 to the winding start end of the first pole piece 11. It is worth noting that, in some embodiments, the winding start end of the first pole piece 11 is provided with the first pole lug 3, and along the direction opposite to the winding direction C2, the second insulating layer 114 extends from the winding end of the first pole piece 11 to the first pole lug 3.

[0075] The second insulating layer 114 can have the same material and function as the first insulating layer 113, which will not be described in detail here. By providing the first insulating layer 113 at the first end 111s and the second insulating layer 114 at the second end 112s, when the first diaphragm 12 contracts, the first insulating layer 113 and the second insulating layer 114 are spaced between the first pole piece 11 and the second pole piece 13, thereby reducing the risk of short circuit between the first pole piece 11 and the second pole piece 13.

[0076] In some embodiments, see Fig.10 , Fig.10 The embodiment of the present application provides Figure 1 Another cross-sectional view of the AA line. A first layer 118 is also sandwiched between the first current collector 111 of the first pole piece 11 and the first active material layer 112. The first layer 118 includes a binder and a conductive agent. The first layer 118 bonds the first current collector 111 and the first active material layer 112, thereby reducing the risk of the first active material layer 112 falling off from the first current collector 111, reducing the above-mentioned first insulating layer 113 and the second insulating layer 114 disposed on the first active material layer 112, and reducing the risk of the first active material layer 112 falling off from the first current collector 111 at the same time, so that when the first diaphragm 12 shrinks, there is a first insulating layer 113 and / or a second insulating layer 114 between the first pole piece 11 and the second pole piece 13.

[0077] In some embodiments, the binder comprises a polymer. In some embodiments, the polymer comprises at least one of polyethylene oxide, polypropylene oxide, polydimethylsiloxane, polymethyl methacrylate, polyvinyl chloride, polyvinylidene fluoride, polyethyleneimine, polyphenylene terephthalamide, polymethoxy polyethylene glycol methacrylate, poly-2-methoxyethyl glycidyl ether, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polyethylene carbonate, polytrimethylene carbonate, or polypropylene carbonate.

[0078] In some embodiments, the conductive agent includes at least one of conductive carbon black, conductive graphite, acetylene black, Ketjen black, porous carbon, graphene, conductive carbon fiber, or carbon nanotubes.

[0079] It is worth noting that, in some embodiments, the first electrode 11 is a negative electrode. When the electrochemical device 100 is charged and discharged, the first active material layer 112 is used for lithium removal or lithium insertion. When the first active material layer 112 inserts lithium, the thickness of the first active material layer 112 increases along the first direction L1. When the first active material layer 112 is delithium, the thickness of the first active material layer 112 decreases. When the first active material layer 112 is delithium or lithium insertion, the first active material layer 112 is easy to fall off from the first current collector 111. By setting the first layer 118, the first layer 118 bonds the first active material layer 112 and the first current collector 111, thereby reducing the risk of the first active material layer 112 falling off from the first current collector 111 when the first active material layer 112 is delithium or lithium insertion. Therefore, by setting the first layer 118, the spacing effect of the first insulating layer 113 and / or the second insulating layer 114 on the first electrode 11 and the second electrode 13 is guaranteed.

[0080] In some embodiments, see Figure 5 and Figure 8 In addition to the first area 1121a and the second area 1121b, the first surface 1121 of the first active material layer 112 facing the first diaphragm 12 also includes a third area 1121c, and the third area 1121c is located at the second end 112s. The second insulating layer 114 is superimposed on the third area 1121c, and a surface of the second insulating layer 114 facing away from the third area 1121c is flush with the second area 1121b. The interface of the first electrode 11 close to the first diaphragm 12 is smooth, which is beneficial to the migration of lithium ions between the first electrode 11 and the second electrode 12.

[0081] It is worth noting that the third region 1121 c is formed by the first surface 1121 being recessed toward the first current collector 111 .

[0082] It is worth noting that, in some embodiments, the preparation method of the first pole piece 11 is to coat the first active material on the first current collector 111 to form a first active material layer 112, and then stack the first insulating layer 113 on the first area 1121a, and stack the second insulating layer 114 on the third area 1121c, and then extrude the product through a roller to form a first pole piece 11 with a smooth interface.

[0083] In some embodiments, see Figure 11-13 , Fig.11 The embodiment of the present application provides Figure 1 Another cross-sectional view of the AA line, Fig.12 The embodiment of this application provides Fig.11 The enlarged view of D3 in the middle. Fig.13 The embodiment of this application provides Fig.11 The first electrode sheet 11 includes, in addition to the first current collector 111, the first active material layer 112 and the first insulating layer 113, a second active material layer 115. The second active material layer 115 is stacked on a surface of the first current collector 111 facing away from the first diaphragm 12, that is, the first active material layer 112 and the second active material layer 115 are respectively arranged on two opposite surfaces of the first current collector 111.

[0084] See also Figure 11-13 , the first electrode sheet 11 further includes a third insulating layer 116 and / or a fourth insulating layer 117. The third insulating layer 116 and the fourth insulating layer 117 are both stacked on the second surface 1151 of the second active material layer 115 facing away from the first diaphragm 12, the third insulating layer 116 is located at the first end 111s, and the fourth insulating layer 117 is located at the second end 112s, that is, along the first direction L1, the third insulating layer 116 and the first insulating layer 113 are arranged relatively at the first end 111s, and the fourth insulating layer 117 and the second insulating layer 114 are arranged relatively at the second end 112s. Along the first direction L1, the width w3 of the third insulating layer 116 satisfies: 2mm≤w3≤10mm, Fig.12 The third insulating layer 116 is entirely overlapped with the second active material layer 115, that is, the overlapped width w3 of the third insulating layer 116 and the second active material layer 115 satisfies: 2mm≤w3≤10mm. In some embodiments, the width w3 of the third insulating layer 116 satisfies: 3mm≤w3≤5mm, that is, the overlapped width w3 of the third insulating layer 116 and the second active material layer 115 satisfies: 3mm≤w3≤5mm. Along the first direction L1, the width w4 of the fourth insulating layer 117 satisfies: 2mm≤w4≤10mm, Fig.13The fourth insulating layer 117 is entirely overlapped with the second active material layer 115, that is, the overlapped width w4 of the fourth insulating layer 117 and the second active material layer 115 satisfies: 2mm≤w4≤10mm. In some embodiments, the width w4 of the fourth insulating layer 117 satisfies: 3mm≤w4≤5mm, that is, the overlapped width w4 of the fourth insulating layer 117 and the second active material layer 115 satisfies: 3mm≤w4≤5mm.

[0085] It is worth noting that the above-mentioned definition of the third insulating layer 116 or the fourth insulating layer 117 is also applicable to the electrode assembly 1 of a laminated structure or the electrode assembly 1 of a wound structure.

[0086] When the electrode assembly 1 is a laminated structure, in some embodiments, along the third direction L3, the third insulating layer 116 may extend from the third end 113s of the first electrode sheet 11 to the fourth end 114s, and the fourth insulating layer 117 may extend from the third end 113s of the first electrode sheet 11 to the fourth end 114s.

[0087] When the electrode assembly 1 is a wound structure, in some embodiments, refer to Fig.14 , Fig.14 The embodiment of the present application provides Figure 1 Another cross-sectional view of the BB line. In the direction opposite to the winding direction C2, the third insulating layer 116 extends from the winding end of the first pole piece 11 toward the winding start end of the first pole piece 11, and the third insulating layer 116 is arranged around the outermost circle of the first pole piece 11 away from the winding center axis C1.

[0088] It can be understood that, along the direction opposite to the winding direction C2, the fourth insulating layer 117 can also extend from the winding end of the first pole piece 11 toward the winding starting end of the first pole piece 11, and the fourth insulating layer 117 is arranged around the outermost circle of the first pole piece 11 away from the winding center axis C1.

[0089] In some other embodiments, see Fig.15 , Fig.15 The embodiment of the present application provides Figure 1 Another cross-sectional view of the BB line. Along the direction opposite to the winding direction C2, the third insulating layer 116 extends from the winding end of the first pole piece 11 to the winding start end of the first pole piece 11. It is worth noting that, in some embodiments, the winding start end of the first pole piece 11 is provided with the first pole lug 3, and along the direction opposite to the winding direction C2, the third insulating layer 116 extends from the winding end of the first pole piece 11 to the first pole lug 3.

[0090] It can be understood that, along the direction opposite to the winding direction C2 , the fourth insulating layer 117 extends from the winding end of the first pole piece 11 to the winding start end of the first pole piece 11 .

[0091] When the electrode assembly 1 is a winding structure, by providing the third insulating layer 116 at the first end 111s and the fourth insulating layer 117 at the second end 112s, when the penultimate circle of the first diaphragm 12 is contracted, the third insulating layer 116 and the fourth insulating layer 117 are spaced between the outermost circle of the first pole piece 11 and the penultimate circle of the second pole piece 13, thereby reducing the risk of short circuit between the first pole piece 11 and the second pole piece 13, and reducing the risk of short circuit inside the electrode assembly 1. The penultimate circle of the first diaphragm 12 is connected to the outermost circle of the first diaphragm 12. The penultimate circle of the first pole piece 11 is connected to the outermost circle of the first pole piece 11.

[0092] It should be noted that the third insulating layer 116 and / or the fourth insulating layer 117 may have the same material and function as the first insulating layer 113 , which will not be described in detail herein.

[0093] In some embodiments, see Fig.12 and Fig.13 , the second surface 1151 of the second active material layer 115 facing away from the first diaphragm 12 includes a first area 1151a, a second area 1151b and a third area 1151c. The first area 1151a is located at the first end 111s, and the third area 1151c is located at the second end 112s. The third insulating layer 116 is stacked on the first area 1151a. The fourth insulating layer 117 is stacked on the third area 1151c. A surface of the third insulating layer 116 facing away from the first area 1151a is flush with the second area 1151b, and / or a surface of the fourth insulating layer 117 facing away from the third area 1151c is flush with the second area 1151b, so that the interface of the first electrode 11 facing away from the first diaphragm 12 is flat.

[0094] It is worth noting that the first region 1151 a is formed by the second surface 1151 being recessed toward the first current collector 111 , and the third region 1151 c is formed by the second surface 1151 being recessed toward the first current collector 111 .

[0095] It is worth noting that, in some embodiments, the preparation method of the first pole piece 11 is to respectively coat the first active material on the two opposite sides of the first current collector 111 to form a first active material layer 112, and the second active material to form a second active material layer 115, and then stack the first insulating layer 113 on the first area 1121a, stack the second insulating layer 114 on the third area 1121c, stack the third insulating layer 116 on the first area 1151a, and stack the fourth insulating layer 117 on the third area 1151c, and then extrude the product through a roller to form a first pole piece 11 with a smooth interface.

[0096] In some embodiments, see Fig.16 , Fig.16The embodiment of the present application provides Figure 1 Another cross-sectional view of the AA line. A second layer 119 is also sandwiched between the first current collector 111 and the second active material layer 115 of the first electrode 11. The second layer 119 includes a binder and a conductive agent. The second layer 119 bonds the first current collector 111 and the second active material layer 115, thereby reducing the risk of the second active material layer 115 falling off from the first current collector 111, reducing the third insulating layer 116 and the fourth insulating layer 117 disposed on the second active material layer 115, and reducing the risk of the second active material layer 115 falling off from the first current collector 111 at the same time. The second layer 119 can have the same material, structure and function as the first layer 118, which will not be repeated here.

[0097] For the second pole piece 13, please refer to Figure 2 , the second electrode sheet 13 has an opposite polarity to the first electrode sheet 11, for example, the first electrode sheet 11 is a negative electrode and the second electrode sheet 13 is a positive electrode, or the first electrode sheet 11 is a positive electrode and the second electrode sheet 13 is a negative electrode. The second electrode sheet 13 may have the same structure and function as the first electrode sheet 11, for example, the second electrode sheet 13 includes a second current collector 131, a third active material layer 132 and a fourth active material layer (not shown), the third active material layer 132 and the fourth active material layer are respectively arranged on two opposite surfaces of the second electrode sheet 13, or the second electrode sheet 13 includes a second current collector 131 and a third active material layer 132, or the second electrode sheet 13 includes a second current collector 131. The structure of the first electrode sheet 11 and the structure of the second electrode sheet 13 may form any combination, for example, the first electrode sheet 11 includes a first current collector 111, a first active material layer 112 and a second active material layer 115, and the second electrode sheet 13 includes a second current collector 131 and a third active material layer 132. For example, the first pole piece 11 includes a first current collector 111 and a first active material layer 112, and the second pole piece 13 includes a second current collector 131 and a third active material layer 132. The structure and function of the second pole piece 13 may refer to the first pole piece 11, and will not be described again.

[0098] For the first pole piece 11 and the second pole piece 13, the second pole piece 13 and the first pole piece 11 may have the same structure and function, but the second pole piece 13 has opposite polarity to the first pole piece 11, and the second pole piece 13 and the first pole piece 11 are made of different materials. In some embodiments, the first current collector 111 of the first pole piece 11 includes copper foil, and the first active material layer 112 and the second active material layer 115 of the first pole piece 11 include graphite. In some embodiments, the second current collector 131 of the second pole piece 13 includes aluminum foil, and the third active material layer 132 and the fourth active material layer of the second pole piece 13 include lithium cobalt oxide.

[0099] In some embodiments, see Fig.17 , Fig.17 The embodiment of the present application provides Figure 1 Another cross-sectional view of the AA line. The electrode assembly 1 also includes a second diaphragm 14, a third pole piece 15, a third diaphragm 16 and a fourth pole piece 17 stacked in sequence along the second direction L2, the second diaphragm 14 is stacked on the first pole piece 11, and the second diaphragm 14 is separated from the first pole piece 11 and the third pole piece 15. Among them, the third pole piece 15 has the same polarity as the second pole piece 13, and the fourth pole piece 17 has the same polarity as the first pole piece 11. Among them, the third pole piece 15 can have the same structure as the second pole piece 13, and the material of the third pole piece 15 can also be the same as that of the second pole piece 13. Among them, the fourth pole piece 17 can have the same structure as the first pole piece 11, and the material of the fourth pole piece 17 can be the same as that of the first pole piece 11.

[0100] When a third insulating layer 116 is provided at the first end 111s of the first pole piece 11 and a fourth insulating layer 117 is provided at the second end 112s, when the second diaphragm 14 contracts, the third insulating layer 116 and the fourth insulating layer 117 are spaced between the first pole piece 11 and the third pole piece 15, thereby reducing the risk of short circuit between the first pole piece 11 and the third pole piece 15 and reducing the risk of short circuit inside the electrode assembly 1.

[0101] It is worth noting that when the electrode assembly 1 further includes the second diaphragm 14, the third electrode piece 15, the third diaphragm 16 and the fourth electrode piece 17, in some embodiments, in the first direction L1, the second electrode piece 13 is arranged closer to the packaging shell 2 containing the electrochemical device 111 than the first electrode piece 11. When the electrochemical device 100 is damaged due to falling or other reasons, the first diaphragm 12 shrinks severely at the first end 111s or the second end 112s, and the first insulating layer 1 is located at the first end 111s. The first insulating layer 1 acts as a spacing between the first electrode piece 11 and the second electrode piece 13, thereby reducing the short circuit between the first electrode piece 11 and the second electrode piece 13 caused by the shrinkage of the first diaphragm 12.

[0102] It is worth noting that when the electrode assembly 1 also includes a second diaphragm 14, a third electrode sheet 15, a third diaphragm 16 and a fourth electrode sheet 17, when a third insulating layer 116 and / or a fourth insulating layer 117 are provided, and the interface of the first electrode sheet 11 facing away from the first diaphragm 12 is smooth, it is beneficial to the migration of lithium ions between the first electrode sheet 11 and the third electrode sheet 15.

[0103] It is worth mentioning that please refer to Figure 2 When the second electrode 13 is disposed close to the packaging shell 2, the second electrode 13 includes a second current collector 131 and a third active material layer 132. The third active material layer 132 is stacked on a surface of the second current collector 131 facing the first diaphragm 12. The surface of the second electrode 131 facing the packaging shell 2 does not need to be provided with a fourth active material layer. Fig.17When the fourth pole piece 17 is disposed next to the packaging shell 2 , the side of the fourth pole piece 17 facing away from the third diaphragm 16 does not need to be provided with an active material layer.

[0104] It can be understood that the second diaphragm 14 is used to separate the first electrode sheet 11 and the third electrode sheet 15, and the first diaphragm 12 is used to separate the first electrode sheet 11 and the second electrode sheet 13. The first electrode sheet 11 includes the above-mentioned first current collector 111, the first active material layer 112 and the second active material layer 115, and the second electrode sheet 13 includes the above-mentioned second current collector 131 and the third active material layer 132, wherein the third active material layer 132 is superimposed on a surface of the second current collector 131 facing the first diaphragm 12.

[0105] It is worth noting that, in some embodiments, the number of the second diaphragm 14, the third pole piece 15, the third diaphragm 16 and the fourth pole piece 17 is multiple groups, and the multiple groups of the second diaphragm 14, the third pole piece 15, the third diaphragm 16 and the fourth pole piece 17 are stacked in a direction opposite to the second direction L2, thereby increasing the external charging and discharging capability of the electrochemical device 100.

[0106] It is worth noting that the second diaphragm 14 and the third diaphragm 16 can have the same material and structure as the first diaphragm 12 .

[0107] In order to facilitate the reader to understand the inventive concept of the present application, 8 specific electrochemical devices provided by the present application are listed below as embodiments, Example 1, Example 2, Example 3, Example 4, Example 5, Example 6, Example 7 and Example 8 for reference, and 2 electrochemical devices in the prior art are listed below as Comparative Examples 1 and Comparative Examples 2. Performance tests were performed on the embodiments and comparative examples, and relevant parameters of the embodiments and comparative examples and the results of the performance tests are shown in Table 1 below.

[0108] Among them, Examples 1-8, Comparative Examples 1 and 2 have the same structure that the electrochemical device includes an electrode assembly, and the electrode assembly is a winding structure. The dimensions of the electrochemical device along the first direction, the second direction and the third direction are 90 mm, 4.8 mm and 66 mm respectively.

[0109] Among them, the different structures of Examples 1-8, Comparative Examples 1 and 2 are that the first electrode sheet of the electrode assembly in Examples 1-8 and Comparative Examples 2 also includes a first insulating layer and a second insulating layer. Along the first direction, that is, along the length direction of the electrochemical device, the width w1 of the first insulating layer and the width w2 of the second insulating layer are equal. In the direction opposite to the winding direction, the first insulating layer extends from the winding end of the first electrode sheet toward the winding start end of the first electrode sheet, and the first insulating layer surrounds the outermost circle of the first electrode sheet away from the winding center axis. The second insulating layer extends from the winding end of the first electrode sheet toward the winding start end of the first electrode sheet, and the second insulating layer surrounds the outermost circle of the first electrode sheet away from the winding center axis.

[0110] The different structures of Examples 1-8 and Comparative Example 2 are that in Examples 1-8, along the first direction, i.e., along the length direction of the electrochemical device, the width w1 of the first insulating layer is 2 mm ≤ w1 ≤ 10 mm, and the width w2 of the second insulating layer is 2 mm ≤ w2 ≤ 10 mm. In Comparative Example 2, along the first direction, i.e., along the length direction of the electrochemical device, the width w1 of the first insulating layer is 12 mm, and the width w2 of the second insulating layer is 12 mm.

[0111] A drop test was performed on Examples 1-8, Comparative Example 1 and Comparative Example 2. The drop test was performed by freely dropping the electrochemical device from a height of 1.8 meters to the surface of a steel plate, dropping for 3 rounds, and dropping 6 times in each round, including dropping the two surfaces of the electrochemical device toward the steel plate respectively along the thickness direction of the electrochemical device, and dropping the four corners of the electrochemical device toward the steel plate respectively. Among them, the drop test was performed on 10 electrochemical devices of each embodiment or Comparative Example 1 or Comparative Example 2. After the drop test, the voltage drop failure ratio of the electrochemical device of Examples 1-8 or Comparative Example 1 or Comparative Example 2 was tested. After the drop test, the interface performance of the first pole piece in the electrochemical device was detected, for example, observing the presence of purple spots, lithium precipitation and other phenomena, or, for example, counting the number of short-circuit points of the first pole piece, so as to evaluate the interface performance of the electrochemical device, and the test results are recorded in Table 1.

[0112] Table 1

[0113]

[0114]

[0115] From Table 1, along the first direction, that is, along the length direction of the electrochemical device, the value of the width w1 of the first insulating layer is: 2mm≤w1≤10mm, and along the first direction, the value of the width w2 of the second insulating layer is: 2mm≤w2≤10mm. The voltage drop failure ratio of the electrochemical device provided in the embodiment of the present application is lower than that of the electrochemical device in Comparative Example 1 without the first insulating layer or the second insulating layer, indicating that the voltage drop failure ratio of the electrochemical device can be effectively reduced by setting the first insulating layer and the second insulating layer, that is, the risk of internal short circuit of the electrode assembly is reduced. When the value of the width w1 of the first insulating layer along the first direction is: 3mm≤w1≤10mm. When the value of the width w2 of the second insulating layer along the first direction is: 3mm≤w2≤10mm, the voltage drop failure ratio of the electrochemical device provided in the embodiment of the present application is zero.

[0116] From Table 1, along the first direction, that is, along the length direction of the electrochemical device, the value of the width w1 of the first insulating layer is: 2mm≤w1≤10mm, and along the first direction, the value of the width w2 of the second insulating layer is: 2mm≤w2≤10mm. Compared with the comparative example 1 in which the first insulating layer or the second insulating layer is not provided, the interface performance of the electrochemical device provided by the embodiment of the present application is basically not affected by the provision of the first insulating layer and the second insulating layer. Along the first direction, when the value of the width w1 of the first insulating layer is 12mm and the value of the width w2 of the second insulating layer is 12mm, the interface performance of the electrochemical device is seriously deteriorated, indicating that when the value of the width w1 of the first insulating layer is 12mm and the value of the width w2 of the second insulating layer is 12mm, the adhesion between the first electrode sheet and the first diaphragm may be affected, thereby affecting the electrical performance of the electrochemical device.

[0117] In summary, along the first direction, the value of the width w1 of the first insulating layer is: 2mm≤w1≤10mm, and along the first direction, the value of the width w2 of the second insulating layer is: 2mm≤w2≤10mm, the overall performance of the electrochemical device provided by the embodiment of the present application is excellent. When 3mm≤w1≤5mm is set, the electrochemical device has good safety performance, electrochemical performance and energy density.

[0118] In the embodiment of the present application, the electrochemical device 100 includes an electrode assembly 1, and the electrode assembly 1 includes a first electrode sheet 11, a first diaphragm 12, and a second electrode sheet 13 stacked in sequence. The first electrode sheet 11 includes a first current collector 111, a first active material layer 112, and a first insulating layer 113. The first active material layer 112 is stacked on a surface of the first current collector 111 facing the first diaphragm 12, and the first insulating layer 113 is stacked on a first surface 1121 of the first active material layer 112 facing the first diaphragm 12. Along the first direction L1, the first electrode sheet 11 has a first end 111s and a second end 112s, and the first end 111s or the second end 112s is connected to the first electrode ear 3, and the first insulating layer 113 is located at the first end 111s; along the first direction L1, the width w1 of the first insulating layer 113 satisfies: 2mm≤w1≤10mm. By providing the first insulating layer 113 at the first end 111s of the first pole piece 11, and limiting the width of the first insulating layer 113 to be no less than 2 mm, when the first diaphragm 12 shrinks, the first insulating layer 113 is spaced between the first pole piece 11 and the second pole piece 13, thereby reducing the risk of short circuit between the first pole piece 11 and the second pole piece 13. In addition, by limiting the width of the first insulating layer 113 to be no more than 10 mm, the influence of the provision of the first insulating layer 113 on the interface performance of the first pole piece 11 is reduced, thereby reducing the influence of the provision of the first insulating layer 113 on the migration of lithium ions between the first pole piece 11 and the second pole piece 13, and the overall performance of the electrochemical device 100 is excellent.

[0119] The embodiment of the present application further provides an electronic device, which includes a load and the electrochemical device 100. The electrochemical device 100 is connected to the load, and the electrochemical device 100 is used to supply power to the load.

[0120] The electronic device may be an energy storage product, a mobile phone, a tablet, a drone, a one-wheeled or two-wheeled electric vehicle, or an electric cleaning tool, etc.

[0121] For example, for the above-mentioned drone, the electrochemical device 100 is mounted on the drone, and the electrochemical device 100 is used to supply power to loads on the drone including a flight system, a control system, and a camera system.

[0122] It should be noted that the preferred embodiments of the present application are given in the specification and drawings of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described in the specification. These embodiments are not used as additional limitations on the content of the present application. The purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. In addition, the above-mentioned technical features continue to be combined with each other to form various embodiments not listed above, which are all regarded as the scope of the description of the present application; further, for ordinary technicians in this field, they can be improved or transformed according to the above description, and all these improvements and transformations should belong to the scope of protection of the claims attached to the present application.

Claims

1. An electrochemical device, comprising an electrode assembly, wherein the electrode assembly comprises a first electrode sheet, a first separator, and a second electrode sheet stacked in sequence; the first electrode sheet comprises a first current collector and a first active material layer, the first active material layer is stacked on a surface of the first current collector, characterized in that: The first pole piece further includes a first insulating layer, which is stacked on a first surface of the first active material layer facing away from the first current collector, and the first insulating layer and the first active material layer extend in the same direction and extend to at least one edge of the first current collector that is oppositely disposed in the first direction; Along the first direction, the first pole piece has a first end and a second end, at least one of the first end or the second end is connected to the first pole ear, and the first insulating layer is located at the first end; Along the first direction, a width w1 of the first insulating layer satisfies: 2mm≤w1≤10mm.

2. The electrochemical device according to claim 1, characterized in that The width w1 of the first insulating layer satisfies: 3mm≤w1≤5mm.

3. The electrochemical device according to claim 1, characterized in that The first surface includes a first area and a second area, the first area is located at the first end, the first insulating layer is stacked on the first area, and a surface of the first insulating layer facing away from the first area is flush with the second area.

4. The electrochemical device according to claim 3, characterized in that The first pole piece further includes a second insulating layer, which is stacked on the first surface and located at the second end.

5. The electrochemical device according to claim 4, characterized in that The first surface further includes a third region, the third region is located at the second end, and a surface of the second insulating layer facing away from the third region is flush with the second region.

6. The electrochemical device according to any one of claims 1 to 5, characterized in that: The first pole piece further includes a second active material layer, and the second active material layer is stacked on the other surface of the first current collector; The first pole piece further includes a third insulating layer, which is stacked on a second surface of the second active material layer facing away from the first current collector, and is located at the first end.

7. The electrochemical device according to claim 6, characterized in that The first pole piece further includes a fourth insulating layer, which is stacked on the second surface and located at the second end.

8. The electrochemical device according to any one of claims 1 to 5, characterized in that: The first pole piece further includes a first layer, and the first layer is stacked between the first current collector and the first active material layer.

9. The electrochemical device according to claim 8, characterized in that The first layer includes a binder and a conductive agent.

10. The electrochemical device according to any one of claims 1 to 5, characterized in that: The first pole piece, the first diaphragm and the second pole piece are wound together into a winding structure, and the winding center axis of the winding structure is arranged along the first direction; The outermost circle of the first pole piece is closer to the winding central axis than the outermost circle of the second pole piece; The first insulating layer extends from the winding end of the first pole piece toward the winding start end of the first pole piece, and the first insulating layer is arranged around the outermost circle of the first pole piece away from the winding center axis.

11. The electrochemical device according to claim 10, characterized in that The first insulating layer extends from a winding end of the first pole piece to a winding start end of the first pole piece.

12. The electrochemical device according to any one of claims 1 to 5, characterized in that: The electrode assembly further includes a second diaphragm, a third pole piece, a third diaphragm and a fourth pole piece stacked in sequence, the second diaphragm is stacked on the first pole piece, and the second diaphragm is spaced between the first pole piece and the third pole piece.

13. An electronic device, characterized in that: The invention comprises a load and the electrochemical device according to any one of claims 1 to 12, wherein the electrochemical device is used to supply power to the load.

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