Electrochemical device, method for manufacturing the same, and electronic device

Abstract

The present application provides an electrochemical device, a method for manufacturing the same, and an electronic device. The electrochemical device includes an electrode assembly, the electrode assembly includes a positive electrode sheet and a negative electrode sheet, the positive electrode sheet includes a positive electrode current collector and a first positive electrode active material layer disposed on the surface of the positive electrode current collector, the negative electrode sheet includes a negative electrode current collector and a first negative electrode active material layer disposed on the surface of the negative electrode current collector, the first negative electrode active material layer includes a lithium replenishment region and a lithium non-replenishment region, the negative electrode sheet is provided with a first groove that penetrates the first negative electrode active material layer and exposes the surface of the negative electrode current collector, the positive electrode sheet further includes a first insulating layer attached to the first positive electrode active material layer facing the first groove, and the lithium non-replenishment region is located within the orthographic projection of the first insulating layer onto the negative electrode sheet. The technical solution provided by the present application can reduce the risk of lithium precipitation in the negative electrode sheet and improve the safety of the electrochemical device by adjusting the dimensions of the lithium non-replenishment region around the position of the first groove.

Description

Cross-reference to related applications

[0001] This application claims priority based on a Chinese patent application filed with the China National Intellectual Property Administration on July 1, 2022, with an application number of 202210763419.7 and an invention title of "Electrochemical Device, Its Manufacturing Method, and Electronic Device". Herein, all of its contents are incorporated into this application by reference.

Technical Field

[0002] This application relates to the field of electrochemical technology, and particularly to electrochemical devices, their manufacturing methods, and electronic devices.

Background Art

[0003] Lithium-ion batteries have characteristics such as high energy density, high operating voltage, low self-discharge rate, small size, and light weight, so they are widely applied in the field of consumer electronics products. With the rapid development of portable electronic devices, the requirements for the energy density, cycle performance, etc. of lithium-ion batteries are becoming increasingly high. In order to further increase the energy density of lithium-ion batteries, lithium can be replenished to the negative electrode sheet. However, lithium precipitation is likely to occur on the negative electrode sheet replenished with lithium, which is disadvantageous for improving the safety of lithium-ion batteries.

Summary of the Invention

[0004] The purpose of this application is to provide an electrochemical device, its manufacturing method, and an electronic device so as to reduce the risk of lithium precipitation on the negative electrode sheet and improve the safety of the electrochemical device. The specific technical solutions are as follows.

[0005] A first aspect of the present application provides an electrochemical device including an electrode assembly. The electrode assembly includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet includes a positive electrode current collector and a first positive electrode active material layer disposed on the surface of the positive electrode current collector. The negative electrode sheet includes a negative electrode current collector and a first negative electrode active material layer disposed on the surface of the negative electrode current collector. The first negative electrode active material layer includes a lithium replenishment region and a lithium non-replenishment region. The negative electrode sheet includes a first groove that penetrates the first negative electrode active material layer and exposes the surface of the negative electrode current collector. The lithium non-replenishment region includes a first edge disposed along a first direction and a second edge disposed along a second direction and connected to the first edge. The first direction is the length direction of the negative electrode sheet, and the second direction is the width direction of the negative electrode sheet. The distance between the first edge and the edge of the first groove adjacent thereto is A1 mm, the dimension of the first groove in the second direction is B1 mm. The positive electrode sheet further includes a first insulating layer attached to the first positive electrode active material layer facing the first groove. The lithium non-replenishment region is located within the orthographic projection of the first insulating layer on the negative electrode sheet. The dimension of the first insulating layer in the second direction is C1 mm, and 0.5 ≦ A1 ≦ C1 - B1 + 1.

[0006] The beneficial effects of the embodiments of the present application are as follows. In the present application, by providing a lithium non-replenishment region in the first negative electrode active material layer around the position of the first groove in the negative electrode sheet, the risk of lithium precipitation in the negative electrode sheet is reduced. Compared with the lithium replenishment region, the lithium non-replenishment region can occlude more lithium ions from the positive electrode. The positive electrode sheet further includes a first insulating layer attached to the first positive electrode active material layer facing the first groove. During the cycling process of the electrochemical device, the adhesion force of the first insulating layer becomes weak due to the expansion and contraction of the first positive electrode active material layer and / or the influence of the electrolyte. Lithium ions in the first positive electrode active material layer covered by the first insulating layer move and precipitate and are occluded in the corresponding negative electrode sheet. Since a lithium non-replenishment region is provided around the position of the first groove in the negative electrode sheet, the local capacity increases, and lithium ions escaping from the region covered by the opposing first insulating layer can be accommodated. Thereby, by replenishing lithium, the capacity of the entire electrochemical device can be improved, the risk of lithium precipitation around the first groove in the negative electrode sheet can be reduced, and the safety of the electrochemical device can be improved.

[0007] In one embodiment of the present application, the distance between the edge of the first groove adjacent to the second edge is A2 mm, the dimension of the first groove in the first direction is B2 mm, the dimension of the first insulating layer in the first direction is C2 mm, and 0.5 ≦ A2 ≦ 0.5×(C2 - B2) + 1. By adjusting A2 within the above range, the risk of lithium precipitation around the first groove in the negative electrode tab can be further reduced, and the safety of the electrochemical device can be improved.

[0008] In one embodiment of the present application, 0.5 ≦ A1 ≦ 9 and 0.5 ≦ A2 ≦ 9. By adjusting the dimension of the lithium non-supplemented region to satisfy the above relationship, the risk of lithium precipitation in the negative electrode tab can be reduced, the safety of the electrochemical device can be improved, and an electrochemical device with a high capacity can be obtained.

[0009] In one embodiment of the present application, 18 ≦ B1 ≦ 22 and 9 ≦ B2 ≦ 13. By adjusting the dimension of the first groove to satisfy the above relationship, it is advantageous for the manufacture of the first groove and the influence on the capacity of the electrochemical device due to an excessive dimension can be reduced.

[0010] In one embodiment of the present application, 25 ≦ C1 ≦ 29 and 23 ≦ C2 ≦ 27. By adjusting the dimension of the first insulating layer to satisfy the above relationship, it is advantageous for improving the accuracy of pasting on the first insulating layer, and the risk of lithium precipitation at the position of the first groove in the negative electrode tab can be reduced, the safety of the electrochemical device can be improved, and the influence on the capacity of the electrochemical device due to an excessive dimension of the first insulating layer can be reduced.

[0011] In one embodiment of the present application, 1.25 ≦ A1 ≦ 9 and 1.25 ≦ A2 ≦ 9. By adjusting the dimension of the lithium non-supplemented region to satisfy the above relationship, the risk of lithium precipitation in the negative electrode tab can be reduced, and the safety and cycle capacity retention rate of the electrochemical device can be improved.

[0012] In one embodiment of the present application, when observed from the thickness direction of the negative electrode sheet, the lithium replenishment region includes a stripe portion. In the first direction, the width of the stripe portion is 0.1 mm to 2 mm, and / or in the thickness direction, the thickness of the stripe portion is 0.04 μm to 0.5 μm. The negative electrode sheet having the above characteristics can improve the initial Coulombic efficiency of the negative electrode sheet, is advantageous for improving the energy density of the electrochemical device, and is also advantageous for improving the manufacturing efficiency of the lithium replenishment region.

[0013] In one embodiment of the present application, the material of the lithium replenishment region includes at least one of lithium carbonate, lithium oxide, lithium nitride, or lithium fluoride. In the process of replenishing lithium to the negative electrode sheet, due to the high activity of lithium metal, it reacts in an air environment and reacts in the formation process of the electrochemical device, forming a layer of lithium-containing compound on the surface of the first negative electrode active material layer. The main components of the lithium-containing compound include at least one of lithium carbonate, lithium nitride, lithium fluoride, or lithium oxide. The negative electrode sheet having the above characteristics can improve the initial Coulombic efficiency of the negative electrode sheet, is advantageous for improving the energy density of the electrochemical device, can improve the resistance on the surface of the negative electrode sheet, is advantageous for reducing the risk of short circuit and short-circuit current, and also, the material of the lithium replenishment region covering the surface of the negative electrode active material can reduce the risk of the solid electrolyte interface film being damaged.

[0014] In one embodiment of the present application, the first insulating layer includes at least one of a single-sided tape, a double-sided tape, or a hot melt tape. By selecting the first insulating layer within the above range, it is advantageous for reducing the risk of lithium precipitation at the position of the first groove in the negative electrode sheet and improving the safety of the electrochemical device.

[0015] In one embodiment of the present application, the negative electrode sheet further includes a negative electrode tab installed in the first groove and electrically connected to the negative electrode current collector. By installing such a structure, the internal resistance of the electrochemical device can be reduced and the charging rate of the electrochemical device can be improved.

[0016] In one embodiment of the present application, the negative electrode sheet further includes a second insulating layer disposed on the negative electrode tab, and the orthographic projection of the second insulating layer onto the negative electrode sheet is located within the lithium non-supplemented region. Thereby, the risk of short circuit between the positive and negative electrodes caused by the burrs on the edge of the negative electrode tab and the connection between the negative electrode tab and the negative electrode current collector can be reduced, and the safety of the electrochemical device can be improved.

[0017] In one embodiment of the present application, the first negative electrode active material layer contains a negative electrode active material, and the negative electrode active material contains a silicon-based material. Thereby, it is advantageous for improving the energy density of the electrochemical device.

[0018] In one embodiment of the present application, in the second direction, the first groove does not penetrate the first negative electrode active material layer. By providing such a structure, the influence of the groove on the capacitance of the electrochemical device can be reduced.

[0019] The second aspect of the present application provides an electronic device including the electrochemical device provided in the first aspect of the present application. Since the electrochemical device provided in the present application has good safety performance, the electronic device provided in the present application has good safety performance.

[0020] The third aspect of the present application provides a method for manufacturing the electrochemical device provided in the first aspect of the present application. Install the first negative electrode active material layer on the surface of the negative electrode current collector. The negative electrode sheet includes a first groove penetrating the first negative electrode active material layer. Lithium-supplemented regions and lithium non-supplemented regions are provided in the first negative electrode active material layer, Install the first positive electrode active material layer on the surface of the positive electrode current collector, and attach the first insulating layer to the first positive electrode active material layer, Stacking the negative electrode sheet and the positive electrode sheet and winding them as an electrode assembly, wherein the first negative electrode active material layer faces the first positive electrode active material layer, and the orthographic projection of the first insulating layer onto the negative electrode sheet covers the lithium non-supplemented region.

[0021] The electrochemical device manufactured by the method provided in the third aspect of the present application can reduce the risk of lithium precipitation in the negative electrode sheet and improve the safety of the electrochemical device.

[0022] In one embodiment of the present application, at least one of a lithium foil or lithium powder is used on the surface of the first negative electrode active material layer to provide a lithium replenishment region in the first negative electrode active material layer. By providing the lithium replenishment region in the above manner, the initial Coulombic efficiency of the negative electrode sheet can be improved, which is advantageous for improving the energy density of the electrochemical device.

[0023] The present application provides an electrochemical device, a method for manufacturing the same, and an electronic device. By providing a lithium non-replenished region in the first negative electrode active material layer around the position of the first groove in the negative electrode sheet, the risk of lithium precipitation on the negative electrode sheet is reduced. Compared with the lithium replenishment region, the lithium non-replenished region can occlude more lithium ions from the positive electrode. The positive electrode sheet further includes a first insulating layer attached to the first positive electrode active material layer facing the first groove. During the cycling process of the electrochemical device, the adhesion force of the first insulating layer becomes weak due to the expansion and contraction of the first positive electrode active material layer and / or the influence of the electrolyte. Lithium ions in the first positive electrode active material layer covered by the first insulating layer move and precipitate and are occluded in the corresponding negative electrode sheet. Since a lithium non-replenished region is provided around the position of the first groove in the negative electrode sheet, the local capacity increases, and lithium ions escaping from the region covered by the opposing insulating layer can be accommodated. Thereby, by replenishing lithium, the capacity of the entire electrochemical device can be improved, and the risk of lithium precipitation around the first groove in the negative electrode sheet can be reduced. According to the technical solution of the present application, the risk of lithium precipitation in the negative electrode sheet can be reduced, and the safety of the electrochemical device can be improved. Of course, when implementing any embodiment of the present application, it is not necessary to achieve all of the above advantages simultaneously.

Brief Description of the Drawings

[0024] To more clearly explain the technical solutions of the present application and the prior art, the following briefly describes the embodiments and the drawings required for the prior art. Of course, the drawings described below are only a part of the embodiments of the present application.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0025] To make the purpose, technical solution, and advantages of the present application clearer, the present application will be described in more detail below with reference to the drawings and examples. Of course, the described examples are only some of the examples of the present application, not all of them. All other technical solutions obtained by those skilled in the art based on the examples in the present application are included in the protection scope of the present application.

[0026] In the specific embodiment of the present application, the lithium-ion battery is used as an example of the electrochemical device to describe the present application, but the electrochemical device of the present application is not limited to the lithium-ion battery.

[0027] In a negative electrode sheet replenished with lithium according to the prior art, a lithium precipitation phenomenon is likely to occur, which is disadvantageous for improving the safety of a lithium ion battery. The inventor has found that when replenishing lithium, by replenishing lithium to a certain region of the negative electrode sheet and not replenishing lithium to a certain region, when improving the capacity of the lithium ion battery, the risk of lithium precipitation in the negative electrode sheet can be reduced, and the safety of the lithium ion battery can be improved.

[0028] In view of this, the first aspect of the present application provides an electrochemical device including an electrode assembly 10. As shown in FIG. 1, the electrode assembly 10 includes a positive electrode sheet 11 and a negative electrode sheet 12. FIG. 2 is a schematic configuration diagram of the positive electrode sheet in an embodiment of the present application, FIG. 3 is a schematic configuration diagram of the negative electrode sheet in an embodiment of the present application, FIG. 4 is a cross-sectional view along the thickness direction of the positive electrode sheet in an embodiment of the present application, and FIG. 5 is a cross-sectional view along the thickness direction of the negative electrode sheet in the A-A cross-section shown in FIG. 3 in an embodiment of the present application. The positive electrode sheet 11 includes a positive electrode current collector 111 and a first positive electrode active material layer 112 provided on the surface of the positive electrode current collector 111. The negative electrode sheet 12 includes a negative electrode current collector 122 and a first negative electrode active material layer 121 provided on the surface of the negative electrode current collector 122. The first negative electrode active material layer 121 includes a lithium replenishment region 123 and a lithium non-replenishment region 124. The lithium non-replenishment region 124 is a region that does not overlap the lithium replenishment region 123 in the region of the first negative electrode active material layer 121. The negative electrode sheet 12 includes a first groove 13 that penetrates the first negative electrode active material layer 121 and exposes the surface of the negative electrode current collector 122. In the embodiment of the present application, the thickness direction perpendicular to the negative electrode sheet 12 is defined as the z direction, the two directions perpendicular to the z direction are defined as the first direction (x direction) and the second direction (y direction), and the first direction (x direction) and the second direction (y direction) are perpendicular to each other. The lithium non-replenishment region 124 includes a first edge 1241 installed along the first direction (x direction) and a second edge 1242 installed along the second direction (y direction) and connected to the first edge 1241. The first direction (x direction) is the length direction of the negative electrode sheet 12, and the second direction (y direction) is the width direction of the negative electrode sheet 12. Referring to FIG. 3, the distance between the first edge 1241 and the edge 131 of the first groove 13 adjacent thereto is defined as A1 mm, that is, the distance between the first edge 1241 and the edge extending along the first direction (x direction) of the first groove 13 and closest to the first edge 1241 is defined as A1 mm, and the dimension of the first groove 13 in the second direction (y direction) is defined as B1 mm. The positive electrode sheet 11 further includes a first insulating layer 14 attached to the first positive electrode active material layer 112 facing the first groove 13. The lithium non-replenishment region 124 is located within the positive projection of the first insulating layer 14 onto the negative electrode sheet 12. The dimension of the first insulating layer 14 in the second direction (y direction) is defined as C1 mm, and 0.5 ≦ A1 ≦ C1 - B1 + 1.

[0029] By providing a lithium non-supplemented region 124 around the position of the first groove 13 in the negative electrode sheet 12, the risk of lithium precipitation in the negative electrode sheet 12 is reduced. Compared with the lithium-supplemented region 123, the lithium non-supplemented region 124 can occlude more lithium ions from the positive electrode. The positive electrode sheet 11 further includes a first insulating layer 14 attached to the first positive electrode active material layer 112 facing the first groove 13. During the cycling process of the electrochemical device, the adhesive force of the first insulating layer 14 becomes weak due to the expansion and contraction of the first positive electrode active material layer 112 and / or the influence of the electrolyte. Lithium ions in the first positive electrode active material layer 112 covered by the first insulating layer 14 move and precipitate, and are occluded in the corresponding negative electrode sheet 12. Since the lithium non-supplemented region 124 is provided around the position of the first groove 13 in the negative electrode sheet 12, the local capacity increases, and the lithium ions escaping from the region covered by the first insulating layer 14 can be accommodated. Thereby, by supplementing lithium, the capacity of the entire electrochemical device is improved, the risk of lithium precipitation around the first groove 13 of the negative electrode sheet 12 is reduced, and the safety of the electrochemical device can be improved.

[0030] In one embodiment of the present application, as shown in FIGS. 6 and 7, a cross-sectional view along the thickness direction of the positive electrode sheet 11 and the negative electrode sheet 12 is shown. The positive electrode sheet 11 includes a positive electrode current collector 111 and a first positive electrode active material layer 112 provided on one surface of the positive electrode current collector 111, and the negative electrode sheet 12 includes a negative electrode current collector 122 and a first negative electrode active material layer 121 provided on one surface of the negative electrode current collector 122. This can also achieve the object of the present application.

[0031] In one embodiment of the present application, the distance between the second edge 1242 and the edge 132 of the first groove 13 adjacent thereto is A2 mm, that is, the distance between the second edge 1242 and the edge that extends along the second direction (y direction) of the first groove 13 and is the closest to the second edge 1242 is A2 mm. The dimension of the first groove 13 in the first direction (x direction) is B2 mm, and the dimension of the first insulating layer 14 in the first direction (x direction) is C2 mm, and 0.5 ≦ A2 ≦ 0.5×(C2 - B2) + 1. By adjusting A2 within the above range, the risk of lithium precipitation around the first groove 13 in the negative electrode sheet 12 can be further reduced, and the safety of the electrochemical device can be improved.

[0032] In one embodiment of the present application, 0.5 ≦ A1 ≦ 9 and 0.5 ≦ A2 ≦ 9. By adjusting the dimension of the lithium non-supplemented region 124 to satisfy the above relationship, the risk of lithium precipitation in the negative electrode sheet 12 can be reduced, the safety of the electrochemical device can be improved, and an electrochemical device with high capacity can be obtained.

[0033] In one embodiment of the present application, 18 ≦ B1 ≦ 22 and 9 ≦ B2 ≦ 13. For example, B1 may be 18, 19, 20, 21, 22 or any range therebetween, and B2 may be 9, 10, 11, 12, 13 or any range therebetween. By adjusting the dimension of the first groove 13 to satisfy the above relationship, it is advantageous for the manufacture of the first groove 13, and the influence on the capacity of the electrochemical device due to an excessive dimension can be reduced.

[0034] In one embodiment of the present application, 25 ≦ C1 ≦ 29 and 23 ≦ C2 ≦ 27. For example, C1 may be 25, 26, 27, 28, 29 or any range therebetween, and C2 may be 23, 24, 25, 26, 27 or any range therebetween. By adjusting the dimension of the first insulating layer 14 to satisfy the above relationship, it is advantageous for improving the accuracy of pasting the first insulating layer 14, and the risk of lithium precipitation at the position of the first groove 13 in the negative electrode sheet 12 can be reduced, the safety of the electrochemical device can be improved, and the influence on the capacity of the electrochemical device due to an excessive dimension of the first insulating layer 14 can be reduced.

[0035] In one embodiment of the present application, 1.25 ≤ A1 ≤ 9 and 1.25 ≤ A2 ≤ 9. By adjusting the dimensions of the lithium non-supplemented region 124 to satisfy the above relationship, the risk of lithium precipitation in the negative electrode sheet 12 can be reduced, and the safety and cycle capacity retention rate of the electrochemical device can be improved.

[0036] In one embodiment of the present application, when observed from the thickness direction (z direction) of the negative electrode sheet 12, the lithium-supplemented region 123 is provided with a stripe portion. In the first direction (x direction), the width of the stripe portion is 0.1 mm to 2 mm, and / or in the thickness direction, the thickness of the stripe portion is 0.04 μm to 0.5 μm. The negative electrode sheet 12 having the above characteristics can improve the initial Coulombic efficiency of the negative electrode sheet 12, is advantageous for improving the energy density of the electrochemical device, and is also advantageous for improving the manufacturing efficiency of the lithium-supplemented region. Specifically, in one embodiment, in the first direction, the width of the stripe portion is 0.1 mm to 2 mm, and in the thickness direction, the thickness of the stripe portion is 0.04 μm to 0.5 μm. In one embodiment, in the first direction, the width of the stripe portion is 0.1 mm to 2 mm. In one embodiment, in the thickness direction, the thickness of the stripe portion is 0.04 μm to 0.5 μm.

[0037] Here, the stripe portion refers to a lithium ribbon having a stripe-shaped gap formed during the process of rolling lithium metal when lithium is supplemented with a lithium metal foil. In the process of laminating the lithium foil to the negative electrode sheet 12, the lithium ribbon having the formed stripe-shaped gap can be retained, so that the stripe portion can be observed from the thickness direction (z direction) of the negative electrode sheet 12. After assembling the electrochemical device with the lithium-supplemented negative electrode sheet 12 and the positive electrode sheet 11, with the absorption of lithium metal by the negative electrode sheet 12 and subsequent formation and capacity treatment, the stripe portion on the surface of the negative electrode sheet 12 is always retained. After the electrochemical device has undergone a cycle process, the lithium-supplemented region 123 in the negative electrode sheet 12 is provided with a stripe portion, and its SEM photograph is shown in FIG. 8, while the lithium non-supplemented region 124 around the position of the first groove 13 is not provided with a stripe portion, and its SEM photograph is shown in FIG. 9.

[0038] In one embodiment of the present application, the material of the lithium replenishment region 123 includes at least one of lithium carbonate, lithium oxide, lithium nitride, or lithium fluoride. In the process of replenishing lithium to the negative electrode sheet 12, since lithium metal is highly active, it reacts with air (for example, oxygen and trace amounts of moisture) and reacts with fluorine-containing substances in the electrolyte during the formation process of the electrochemical device, forming a layer of lithium-containing compound on the surface of the first negative electrode active material layer 121. The main components of the lithium-containing compound include at least one of lithium carbonate, lithium nitride, lithium fluoride, or lithium oxide. After assembling the electrode assembly and injecting the electrolyte, lithium metal reacts rapidly with the negative electrode active material, but the lithium-containing compound layer does not react with the negative electrode active material. After the active lithium metal reacts with the negative electrode active material, the lithium-containing compound layer remains on the surface of the negative electrode sheet 12. As shown in FIG. 10, the lithium replenishment region 123 forms a layer of lithium-containing compound layer (between the two black dashed lines) on the surface of the negative electrode active material, and the thickness of the lithium-containing compound layer is 0.04 μm to 0.5 μm. The negative electrode sheet 12 having the above characteristics can improve the initial coulombic efficiency of the negative electrode sheet 12, is advantageous for improving the energy density of the electrochemical device, can improve the resistance on the surface of the negative electrode sheet 12, and is advantageous for reducing the risk of short circuit and the short-circuit current. In addition, the material of the lithium replenishment region 123 covering the surface of the negative electrode active material can reduce the risk of its solid electrolyte interface film being damaged.

[0039] In one embodiment of the present application, the first insulating layer 14 includes at least one of a single-sided tape, a double-sided tape, or a hot melt tape. By selecting the insulating layer within the above range, it is advantageous to reduce the risk of lithium precipitation at the position of the first groove 13 in the negative electrode sheet 12 and improve the safety of the electrochemical device. In the present application, there is no particular limitation on the material of the first insulating layer 14, as long as the object of the present application can be achieved. For example, the single-sided tape includes a base material layer and an adhesive layer. The material of the base material layer includes at least one of polyfluoroolefin, polyethylene terephthalate (PET), polyimide (PI), polyamideimide (PAI), polyvinyl chloride (PVC), or polyolefin (POF, such as a biaxially stretched polyolefin heat shrinkable film), but is not limited thereto. The polyfluoroolefin includes polytetrafluoroethylene or polyvinylidene fluoride, but is not limited thereto. The adhesive layer includes a binder, and the binder includes at least one of carboxymethyl cellulose, styrene butadiene rubber, polyvinylidene fluoride, polytetrafluoroethylene, fluororubber, polyamide, polypropylene alcohol, sodium polyacrylate, polyetherimide, or acrylate, but is not limited thereto.

[0040] In one embodiment of the present application, the negative electrode sheet 12 further includes a negative electrode tab installed in the first groove 13 and electrically connected to the negative electrode current collector 122. Electrically connected means that it is conductive between the negative electrode tab and the negative electrode current collector 122. As shown in FIG. 5, in one embodiment, the first grooves 13 are installed on both sides of the negative electrode current collector 122, and the negative electrode tab is installed in at least one of the first grooves 13. By providing such a structure, the internal resistance of the electrochemical device can be reduced and the charging rate of the electrochemical device can be improved.

[0041] In one embodiment of the present application, the negative electrode tab 12 further includes a second insulating layer disposed on the negative electrode tab, and the orthographic projection of the second insulating layer onto the negative electrode tab 12 is located within the lithium non-supplemented region 124. The second insulating layer includes, but is not limited to, tapes such as single-sided tapes. By disposing the second insulating layer as described above, the risk of short circuit between the positive and negative electrodes caused by the burrs at the edge of the negative electrode tab and the connection between the negative electrode tab and the negative electrode current collector 122 can be reduced, and the safety of the electrochemical device can be improved.

[0042] In one embodiment of the present application, the first negative electrode active material layer 121 contains a negative electrode active material, the negative electrode active material contains a silicon-based material, and the silicon-based material contains at least one of silicon, silicon oxide (SiO x , 0 < x ≤ 2), silicon alloy, or silicon-carbon composite. The negative electrode active material of the present application may include at least one of graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, lithium titanate Li4Ti5O 12 with a spinel structure, Li-Al alloy, or metallic lithium. By selecting materials within the above range, it is advantageous for improving the energy density of the electrochemical device.

[0043] In one embodiment of the present application, in the second direction, the first groove 13 does not penetrate the first negative electrode active material layer 121. By providing such a structure, the influence on the capacity of the electrochemical device due to the installation of the groove can be reduced.

[0044] The electrochemical device of the present application is not particularly limited and may include any device that generates an electrochemical reaction. In one embodiment of the present application, the electrochemical device includes, but is not limited to, a lithium-ion secondary battery (lithium-ion battery), a lithium polymer secondary battery, or a lithium-ion polymer secondary battery. In one embodiment of the present application, the lithium-ion battery structure of the present application includes a wound structure or a stacked structure. The lithium-ion battery structure of the present application includes, but is not limited to, a soft-pack lithium-ion battery, a square hard-shell battery, or a cylindrical hard-shell battery.

[0045] The present application is not particularly limited with respect to the negative electrode current collector 122, as long as the object of the present application can be achieved. For example, the negative electrode current collector 122 may include a copper foil, a copper alloy foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foam, a copper foam, a composite current collector, or the like. The present application is not particularly limited with respect to the thickness of the negative electrode current collector, as long as the object of the present application can be achieved. For example, the thickness of the negative electrode current collector is 4 μm to 10 μm.

[0046] In the present application, the first negative electrode active material layer 121 may be provided on one surface in the thickness direction of the negative electrode current collector 122, or may be provided on two surfaces in the thickness direction of the negative electrode current collector 122. Here, the "surface" may be all regions of the negative electrode current collector 122, or may be a part of the regions of the negative electrode current collector 122. The present application is not particularly limited, as long as the object of the present application can be achieved.

[0047] The present application is not particularly limited with respect to the thickness of the first negative electrode active material layer 121, as long as the object of the present application can be achieved. For example, the thickness of the first negative electrode active material layer on one side may be 30 μm to 160 μm.

[0048] In the present application, a first negative electrode active material layer 121 is provided on the surface of the negative electrode current collector 122, or a functional layer is further included between the negative electrode current collector 122 and the first negative electrode active material layer 121. For example, the functional layer includes, but is not limited to, a conductive adhesive layer. The conductive adhesive layer may include a conductive agent and a binder. The present application is not particularly limited to the conductive agent, and it is sufficient if the object of the present application can be achieved. For example, it includes, but is not limited to, at least one of a carbon-based material, a metal-based material, or a conductive polymer. The above carbon-based material is at least one selected from natural graphite, artificial graphite, conductive carbon black, acetylene black, ketjen black, or carbon fiber. The above metal-based material may include, but is not limited to, metal powder and / or metal fiber. Specifically, the metal may include, but is not limited to, at least one of copper, nickel, aluminum, or silver. The conductive polymer includes, but is not limited to, at least one of a polyphenylene derivative, polyaniline, polythiophene, polyacetylene, or polypyrrole.

[0049] The present application is not particularly limited to the binder, and it is sufficient if the object of the present application can be achieved. For example, it may include, but is not limited to, at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an ethylene oxide-containing polymer, polyvinyl pyrrolidone, polyamide, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylic acid, styrene butadiene rubber, acrylated styrene butadiene rubber, epoxy resin, or nylon.

[0050] The present application is not particularly limited to the positive electrode current collector 111, and it is sufficient if the object of the present application can be achieved. For example, the positive electrode current collector 111 may include an aluminum foil, an aluminum alloy foil, a composite current collector, or the like. The present application is not particularly limited to the thickness of the positive electrode current collector 111, and it is sufficient if the object of the present application can be achieved. For example, the thickness of the positive electrode current collector 111 is 5 μm to 20 μm, preferably 6 μm to 18 μm.

[0051] The first positive electrode active material layer 112 of the present application may contain a positive electrode active material. The present application is not particularly limited with respect to the type of the positive electrode active material, as long as the object of the present application can be achieved. For example, the positive electrode active material may include at least one of lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide, lithium manganate, or lithium iron manganese phosphate. In the present application, the positive electrode active material may further contain a non-metallic element. For example, the non-metallic element may include at least one of fluorine, phosphorus, boron, chlorine, silicon, or sulfur, and these elements can further improve the stability of the positive electrode active material.

[0052] The present application is not particularly limited with respect to the thickness of the first positive electrode active material layer 112, as long as the object of the present application can be achieved. For example, the thickness of the first positive electrode active material layer on one side may be 30 μm to 120 μm.

[0053] In the present application, the first positive electrode active material layer 112 may be disposed on one surface in the thickness direction of the positive electrode current collector 111, or may be disposed on two surfaces in the thickness direction of the positive electrode current collector 111. Here, the "surface" may be all regions of the positive electrode current collector, or may be a part of the regions of the positive electrode current collector. The present application is not particularly limited, as long as the object of the present application can be achieved.

[0054] The present application is not particularly limited with respect to the separator and the electrolyte, and those skilled in the art may select according to actual needs, as long as the object of the present application can be achieved.

[0055] The method for adjusting the dimensions of the lithium replenishment region 123 and the non-lithium-replenished region 124 is not particularly limited, and methods in this field may be adopted. Exemplarily, a tape may be attached to a region on the surface of the negative electrode sheet 12 where lithium replenishment is not necessary, and the dimensions of the tape may be adjusted according to the dimensions of the planned non-lithium-replenished region 124. Then, a lithium foil is subjected to a composite or rolling process on the surface of the negative electrode sheet 12, and the tape is removed after the lithium replenishment is completed. In this way, a negative electrode sheet 12 with lithium replenished in some regions is obtained.

[0056] The second aspect of the present application provides an electronic device including the electrochemical device provided in the first aspect of the present application. Since the electrochemical device provided in the present application has good safety performance, the electronic device provided in the present application has good safety performance.

[0057] The present application is not particularly limited to an electronic device, and it may be any known electronic device used in the prior art. In some embodiments, the electronic device may include, but is not limited to, a notebook computer, a pen-input computer, a mobile computer, an e-book player, a mobile phone, a portable facsimile machine, a portable copier, a portable printer, a stereo headset, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini CD, a transceiver, an electronic notebook, a calculator, a memory card, a portable tape recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, an auxiliary bicycle, a bicycle, a lighting fixture, a toy, a game machine, a clock, a power tool, a flash, a camera, a large household storage battery, or a lithium-ion capacitor, etc.

[0058] The third aspect of the present application provides a method for manufacturing the electrochemical device provided in the first aspect of the present application. A first negative electrode active material layer 121 is provided on the surface of the negative electrode current collector 122, the negative electrode sheet 12 is provided with a first groove 13 penetrating the first negative electrode active material layer 121, and a lithium replenishment region 123 and a non-lithium-replenished region 124 are provided in the first negative electrode active material layer 121, A first positive electrode active material layer 112 is provided on the surface of the positive electrode current collector 111, and a first insulating layer 14 is attached to the first positive electrode active material layer 112. The negative electrode sheet 12 and the positive electrode sheet 11 are laminated and wound to form an electrode assembly 10, wherein the first negative electrode active material layer 121 faces the first positive electrode active material layer 112, and the positive projection of the first insulating layer 14 onto the negative electrode sheet 12 covers the lithium non-supplemented region 124.

[0059] By adopting the electrochemical device manufactured by the method provided in the third aspect of the present application, the risk of lithium precipitation in the negative electrode sheet 12 can be reduced, and the safety of the electrochemical device can be improved.

[0060] In the present application, the first insulating layer 14 includes at least one of a single-sided tape, a double-sided tape, or a hot melt tape. The present application is not particularly limited to the material of the first insulating layer 14, and it may be, for example, at least one of polyethylene, polypropylene, or polyvinylidene fluoride, as long as the object of the present application can be achieved.

[0061] The present application is not particularly limited to the method of supplementing lithium, and those skilled in the art may select according to actual needs, as long as the object of the present application can be achieved. For example, in a drying chamber (environmental humidity < 1.7%), a lithium foil is rolled to a thickness on the micron order, and a composite or rolling treatment is performed on the surface of the negative electrode sheet 12.

[0062] In the present application, the electrode assembly 10 is packaged to obtain an electrochemical device, and the present application is not particularly limited to the packaging process, as long as the object of the present application can be achieved.

[0063] In an embodiment of the present application, at least one of a lithium foil or lithium powder is used on the surface of the first negative electrode active material layer 121 to provide a lithium supplementation region 123 in the first negative electrode active material layer 121. By providing the lithium supplementation region 123 as described above, the initial Coulombic efficiency of the negative electrode sheet 12 can be improved, which is advantageous for improving the energy density of the electrochemical device.

[0064] Hereinafter, embodiments of the present application will be described in more detail with reference to examples and comparative examples. Each test and evaluation is conducted according to the following methods. Unless otherwise specified, "parts" and "%" are based on mass.

[0065] Measurement methods and equipment: Measurement of the morphology of the negative electrode sheet: The negative electrode sheet that has been cycled in a drying chamber (humidity < 1.7%) is disassembled, washed three times with dimethyl carbonate (DMC), then dried, and the morphology of the negative electrode sheet is observed with a scanning electron microscope (SEM), an SEM photograph is taken, and the width of the stripe portion is measured.

[0066] Measurement of the cross-sectional morphology of the negative electrode sheet: The disassembled negative electrode sheet is polished with argon ions to prepare a sample, the cross-sectional morphology is photographed with SEM, and the thickness of the stripe portion and the thickness of the lithium-containing compound layer on the surface of the negative electrode sheet are measured.

[0067] High-temperature cycle acceleration measurement: Measurement environmental temperature: 45 ± 5 °C Cycle measurement flow: The lithium-ion battery is charged to the full charge state at the maximum rated current, left standing for 5 min, discharged to 3.0 V at a constant current of 0.5 C (rate), and the above charge-discharge flow is repeated 500 cycles, then charged to the full charge state at the maximum rated current and circulated up to 500 cycles. Then, each lithium-ion battery is disassembled, and the lithium precipitation situation around the first groove is observed.

[0068] Judgment of the degree of lithium precipitation: The lithium-ion battery that has been cycled in a drying chamber (humidity < 1.7%) is disassembled, and the lithium precipitation situation around the first groove is photographed and recorded. The situation where no lithium precipitation is found or the area of lithium precipitation < 2% is regarded as no lithium precipitation, the situation where the area of lithium precipitation is 2% - 20% is regarded as slight lithium precipitation, the situation where the area of lithium precipitation > 20% is regarded as serious lithium precipitation, and the fraction of the area of lithium precipitation is calculated based on the area of the first insulating layer on the first positive electrode active material layer.

[0069] Measurement of Capacity: In an environment of 25 °C, charge with a charging current of 0.5C (rate) until the upper limit voltage reaches 4.2V, and then perform constant current discharge with a discharge current of 0.2C until the final voltage reaches 2.8V. Calculate the initial discharge capacity of 0.2C and use it as the capacity of the lithium-ion battery.

[0070] Example 1-1 <Fabrication of Negative Electrode Sheet> Graphite, silicon oxide (SiO x , x = 1), carboxymethyl cellulose and styrene-butadiene rubber are mixed at a mass ratio of 96.7:10:1.3:1.0, and then deionized water is added as a solvent to prepare a negative electrode slurry with a solid content of 60 wt%, and stirred uniformly. The negative electrode slurry is uniformly coated on one surface of a copper foil of a negative electrode current collector with a thickness of 10 μm, dried under the condition of 110 °C, and a negative electrode sheet with a first negative electrode active material layer coated on one side and a coating thickness of 150 μm is obtained. Then, the above process is repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet with a first negative electrode active material layer coated on both sides. After the coating is completed, the negative electrode sheet is cold-pressed, and tab forming, stripping treatment, laser cleaning, etc. are performed to obtain a negative electrode sheet with a first groove at the tab. The first groove is for welding the negative electrode tab, and a negative electrode sheet of 83.3 mm × 1494 mm is obtained. The dimensions B1 of the first groove at the tab are 20 mm, and B2 is 9 mm.

[0071] Tape is attached to the area on the surface of the negative electrode sheet where lithium supplementation is not required. The dimensions of the tape can be adjusted according to the dimensions of the planned lithium non-supplemented area, that is, by adjusting the dimensions of the tape, A1 and A2 can be adjusted. Then, in a drying chamber (environmental humidity < 1.7%), the lithium foil is rolled to a thickness on the micron order (2 μm), and composite or rolling treatment is performed on the surface of the fabricated negative electrode sheet to remove the tape on the surface of the negative electrode sheet, and a negative electrode sheet with lithium not supplemented around the first groove is obtained. The dimension A1 of the lithium non-supplemented area around the first groove is 0.5 mm, and A2 is 5 mm.

[0072] <Fabrication of Positive Electrode Sheet> Lithium cobalt oxide (LiCoO₂) as the positive electrode active material, conductive carbon black as the conductive agent, and polyvinylidene fluoride (PVDF) are mixed at a mass ratio of 97:1.4:1.6, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a positive electrode slurry with a solid content of 75 wt%, and it is uniformly stirred. The positive electrode slurry is uniformly coated on one surface of an aluminum foil positive electrode current collector with a thickness of 10 μm, dried under the condition of 110 °C, and a positive electrode sheet with the positive electrode active material coated on one side and the thickness of the first positive electrode active material layer being 110 μm is obtained. Then, except for pre-setting an empty foil area at one end of the positive electrode current collector for welding the positive electrode tab, the same operations as above are performed to obtain a positive electrode sheet with the positive electrode active material coated on both sides. After the coating is completed, the positive electrode sheet is cold-pressed and then subjected to strip treatment to obtain and prepare a positive electrode sheet of 81.9 mm × 1490 mm.

[0073] <Preparation of Electrolyte> In a glove box with a dry argon gas atmosphere, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and ethyl propionate (EP) as organic solvents are mixed at a mass ratio of EC:PC:DEC:EP = 3:1:3:3, and lithium hexafluorophosphate (LiPF₆) as a lithium salt is added to the organic solvent, dissolved and uniformly mixed to obtain an electrolyte with a lithium salt concentration of 1 mol / L.

[0074] <Preparation of Separator> PVDF and aluminum oxide ceramics are mixed at a mass ratio of 9:1, deionized water is added as a solvent to prepare a slurry with a solid content of 12 wt%, uniformly stirred, and the slurry is uniformly coated on one surface of a polyethylene thin film substrate with a thickness of 15 μm and dried to obtain a separator.

[0075] <Fabrication of Lithium-Ion Battery> Weld a tab to the first groove in the fabricated negative electrode sheet described above, and weld a positive electrode tab to the empty foil area previously provided at one end of the positive electrode sheet. Stack the positive electrode sheet, the separator, and the negative electrode sheet in this order so that the separator is interposed between the positive electrode sheet and the negative electrode sheet to play a role of isolation. Then, attach a first insulating layer (single-sided tape, the dimensions of the first insulating layer are C1 = 29 mm and C2 = 27 mm) to the first positive electrode active material layer facing the first groove where the negative electrode tab is welded, so that the lithium non-supplemented area around the first groove is positioned within the orthographic projection of the insulating layer onto the negative electrode sheet. Then, start winding from one end away from the positive electrode tab to obtain an electrode assembly. Place the electrode assembly in an aluminum packaging material, put it into a vacuum oven at 85 °C, dry it for 12 hours to remove moisture, inject the prepared electrolyte, perform vacuum packaging, static placement, formation (charge to 3.5 V at a constant current of 0.02 C and then charge to 3.9 V at a constant current of 0.1 C), shaping, and capacity treatment, and then obtain a lithium-ion battery. The designed battery capacity of the lithium-ion battery is 5000 mAh.

[0076] Examples 1-2 to Examples 1-6 It is the same as Example 1-1 except that the dimensions A1 and A2 of the lithium non-supplemented area around the first groove are adjusted as shown in Table 1.

[0077] Examples 2-1 to Examples 2-24 It is the same as Example 1-1 except that the dimensions A1 and A2 of the lithium non-supplemented area around the first groove are adjusted as shown in Table 2.

[0078] Comparative Examples 1 to Comparative Examples 4 It is the same as Example 1-1 except that the dimensions A1 and A2 of the lithium non-supplemented area around the first groove are adjusted as shown in Table 2.

[0079] The relevant parameters and performance measurements of each example and comparative example are shown in Table 1 and Table 2.

[0080]

Table 1

[0081]

Table 2

[0082] As can be seen from Examples 1-1 to 1-6, when the dimensions of the lithium non-supplemented region around the first groove are set within the scope of the present application, the local capacity ratio of the negative electrode sheet and the positive electrode sheet is large, and the negative electrode sheet can effectively store the lithium ions escaping from the positive electrode sheet covered by the opposing insulating layer. As a result, the problem of lithium precipitation around the first groove in the negative electrode sheet is improved, the risk of lithium precipitation in the negative electrode sheet is reduced, and the safety of the lithium ion battery can be improved.

[0083] As can be seen from Examples 2-1 to 2-24 and Comparative Example 2, within the scope of the present application, as the dimensions of the lithium non-supplemented region increase, the local capacity ratio of the negative electrode sheet and the positive electrode sheet increases, and the negative electrode sheet can effectively store the lithium ions escaping from the positive electrode sheet covered by the opposing insulating layer. As a result, the problem of lithium precipitation around the first groove in the negative electrode sheet is improved, the risk of lithium precipitation in the negative electrode sheet is reduced, and the safety of the lithium ion battery can be improved.

[0084] As can be seen from Comparative Example 1, when lithium was supplemented around all the first grooves, a serious lithium precipitation phenomenon occurred around the position of the first groove in the negative electrode sheet. The reason is as follows. During the cycling process, the adhesion of the first insulating layer in the positive electrode sheet corresponding to the position of the first groove in the negative electrode sheet becomes weak due to the expansion and contraction of the positive electrode active layer and the immersion of the electrolyte, and the surface layer lithium ions at the position covered by the first insulating layer move and precipitate, resulting in excessive lithium intercalation and precipitation in the opposing negative electrode sheet, and a serious lithium precipitation phenomenon occurs, which is disadvantageous to the safety of the lithium ion battery.

[0085] As can be seen from Examples 2-1 to 2-24 and Comparative Examples 3 to 4 above, when the dimensions of the lithium non-supplemented region around the first groove are set to be too large, the influence on the capacity of the battery becomes significant.

[0086] The technical solution provided in this application can effectively reduce the risk of lithium precipitation in the negative electrode sheet, improve the safety of lithium-ion batteries, improve the energy density of lithium-ion batteries, and at the same time maintain good cycle performance.

[0087] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of this application should be included within the protection scope of this application.

Claims

1. An electrochemical device including an electrode assembly, wherein the electrode assembly includes a positive electrode sheet and a negative electrode sheet, the positive electrode sheet includes a positive electrode current collector and a first positive electrode active material layer disposed on the surface of the positive electrode current collector, the negative electrode sheet includes a negative electrode current collector and a first negative electrode active material layer disposed on the surface of the negative electrode current collector, the first negative electrode active material layer includes a lithium replenishment region and a lithium non-replenishment region, and the negative electrode sheet is provided with a first groove that penetrates the first negative electrode active material layer and exposes the surface of the negative electrode current collector. The lithium non-replenishment region includes a first edge disposed along a first direction and a second edge disposed along a second direction and connected to the first edge, the first direction is the length direction of the negative electrode sheet, and the second direction is the width direction of the negative electrode sheet. Let the distance between the first edge and the edge of the first groove adjacent to the first edge be A １ mm, and let the dimension of the first groove in the second direction be B １ mm The positive electrode sheet further includes a first insulating layer attached to the first positive electrode active material layer facing the first groove, the lithium uncomplemented region is located within the orthographic projection of the first insulating layer onto the negative electrode sheet, and the dimension of the first insulating layer in the second direction is C １ mm, and 0.5 ≤ A １ ≤ C １ -B １ +1, Electrochemical device.

2. Let the distance between the edge of the first groove adjacent to the second edge be A ２ mm, let the dimension of the first groove in the first direction be B ２ mm, let the dimension of the first insulating layer in the first direction be C ２ mm, and 0.5 ≤ A ２ ≤ 0.5 × (C ２ − B ２ ) + 1 The electrochemical device according to claim 1.

3. 0.5 ≤ A １ ≤ 9, and 0.5 ≤ A ２ ≤ 9 The electrochemical device according to claim 2.

4. 18 ≤ B １ ≤ 22, and 9 ≤ B ２ ≤ 13 The electrochemical device according to claim 2.

5. 25 ≤ C １ ≤ 29, and 23 ≤ C ２ ≤ 27 The electrochemical device according to claim 2.

6. 1.25 ≤ A １ ≤ 9, and 1.25 ≤ A ２ ≤ 9 The electrochemical device according to claim 2.

7. When observed from the thickness direction of the negative electrode sheet, the lithium replenishment region includes a stripe portion. In the first direction, the width of the stripe portion is 0.1 mm to 2 mm, and / or In the thickness direction, the thickness of the stripe portion is 0.04 μm to 0.5 μm. The electrochemical device according to claim 1.

8. The material of the lithium replenishment region includes at least one of lithium carbonate, lithium oxide, lithium nitride, or lithium fluoride. The electrochemical device according to claim 1.

9. The first insulating layer includes at least one of a single-sided tape, a double-sided tape, or a hot melt tape. The electrochemical device according to claim 1.

10. The negative electrode sheet further includes a negative electrode tab disposed in the first groove and electrically connected to the negative electrode current collector. The electrochemical device according to claim 1.

11. The negative electrode sheet further includes a second insulating layer disposed on the negative electrode tab, and the orthographic projection of the second insulating layer on the negative electrode sheet is located within the lithium non-replenishment region. The electrochemical device according to claim 10.

12. The first negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes a silicon-based material. The electrochemical device according to claim 1.

13. In the second direction, the first groove does not penetrate the first negative electrode active material layer. The electrochemical device according to claim 1.

14. An electronic device comprising the electrochemical device according to any one of Claims 1 to 13. Electronic device.

15. A method for manufacturing the electrochemical device according to any one of Claims 1 to 13, comprising: placing the first negative electrode active material layer on the surface of the negative electrode current collector, the negative electrode sheet including a first groove penetrating the first negative electrode active material layer, and providing a lithium replenishment region and a lithium non-replenishment region in the first negative electrode active material layer; placing the first positive electrode active material layer on the surface of the positive electrode current collector, and attaching the first insulating layer to the first positive electrode active material layer; laminating the negative electrode sheet and the positive electrode sheet and winding them to form the electrode assembly, wherein the first negative electrode active material layer faces the first positive electrode active material layer, and a positive projection of the first insulating layer onto the negative electrode sheet covers the lithium non-replenishment region. Method.

16. The manufacturing method according to Claim 15, wherein a lithium replenishment region is provided in the first negative electrode active material layer by using at least one of a lithium foil and lithium powder on the surface of the first negative electrode active material layer. The manufacturing method according to Claim 15.

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