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

Abstract

The present invention 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, the negative electrode sheet includes a negative electrode current collector and a first negative electrode active material layer, the first negative electrode active material layer includes a lithium replenishment region and a lithium non-replenishment region, the lithium non-replenishment region is a region whose area does not overlap with the lithium replenishment region, and the lithium non-replenishment region is provided in the edge region of the negative electrode sheet. The present invention can reduce the risk of lithium precipitation on the negative electrode sheet and improve the safety and reliability of the electrochemical device by adjusting the dimensions of the lithium non-replenishment region in the edge region of the negative electrode sheet.

Description

Cross-Reference to Related Applications

[0001] The present invention claims priority from the Chinese Patent Application filed with the China National Intellectual Property Administration on July 1, 2022, with application number 202210763436.0 and the title of invention "Electrochemical Device, Manufacturing Method Thereof, and Electronic Device", the entire content of which is incorporated into the present application by reference. Technical Field

[0002] The present invention relates to the field of electrochemical technology, and in particular to an electrochemical device, a manufacturing method thereof, and an electronic device. Background Art

[0003] Lithium-ion batteries have characteristics such as high operating voltage, high energy density, long cycle life, and wide operating temperature range. Based on these excellent characteristics, lithium-ion batteries are widely applied in three fields: consumer electronics, power batteries, and energy storage.

[0004] To further improve the energy density of lithium-ion batteries, this can be achieved by replenishing lithium on the surface of the negative electrode sheet. However, lithium precipitation is prone to occur on the negative electrode sheet after the above-mentioned lithium replenishment, and in particular, lithium precipitation is prone to occur at the edges, which affects the safety of lithium-ion batteries. Summary of the Invention Problem to be Solved by the Invention

[0005] An object of the present invention is to provide an electrochemical device, a manufacturing method thereof, and an electronic device, so as to reduce the risk of lithium precipitation on a negative electrode sheet and improve the safety and reliability of the electrochemical device. Specific technical measures are as follows. Means for Solving the Problem

[0006] A first aspect of the present invention provides an electrochemical apparatus comprising an electrode assembly, the electrode assembly comprising a positive electrode piece and a negative electrode piece, the positive electrode piece comprising a positive electrode current collector and a first positive electrode active material layer provided on the surface of the positive electrode current collector, the negative electrode piece comprising a negative electrode current collector and a first negative electrode active material layer provided on the surface of the negative electrode current collector, the first negative electrode active material layer comprising a lithium-replenished region and a lithium-unreplenished region, the lithium-unreplenished region being a region of the first negative electrode active material layer whose area does not overlap with that of the lithium-replenished region, the width dimension of the first negative electrode active material layer being B1 mm, the width dimension of the first positive electrode active material layer being B2 mm, and the distance between one edge of the first negative electrode active material layer extending along the longitudinal direction and the adjacent edge of the lithium-replenished region extending along the longitudinal direction being B4 mm, the equation 0.15 ≤ B4 ≤ 1 / 2 × (B1 - B2) + 1 is satisfied.

[0007] The beneficial effects of the embodiments of the present invention are as follows. The present invention reduces the risk of lithium deposition on the negative electrode piece by providing a lithium-unreplenished region in the first negative electrode active material layer at the edge region of the negative electrode piece. During the cycle process of the electrochemical apparatus, the lithium-unreplenished region can absorb more lithium ions from the positive electrode than the lithium-replenished region, increasing the local capacity ratio of the edge region of the negative electrode piece and allowing it to accommodate more lithium ions from the edge of the opposing positive electrode piece. This reduces the risk of lithium deposition at the widthwise edge of the negative electrode piece, improves the safety reliability of the electrochemical apparatus, and balances the energy density of the electrochemical apparatus.

[0008] In one embodiment of the present invention, when the longitudinal dimension of the first negative electrode active material layer is A1 mm, the longitudinal dimension of the first positive electrode active material layer is A2 mm, and the distance between one edge extending along the width direction in the first negative electrode active material layer and the adjacent edge of the lithium replenishment region extending along the width direction is A4 mm, the following condition is met: 0.15 ≤ A4 ≤ 1 / 2 × (A1 - A2) + 1. By adjusting A4 to within the above range, the risk of lithium deposition at the longitudinal edges of the negative electrode piece can be reduced, and the safety and reliability of the electrochemical apparatus can be improved.

[0009] In one embodiment of the present invention, when the width dimension of the lithium replenishment area is B3 mm, the condition B4 = (B1 - B3) / 2 is satisfied. By the above technical means, the risk of the positive electrode piece exceeding the negative electrode piece in the width direction can be reduced, the risk of lithium deposition on the negative electrode piece can be reduced, and the safety reliability of the electrochemical apparatus can be improved.

[0010] In one embodiment of the present invention, when the longitudinal dimension of the lithium replenishment area is A3 mm, the condition A4 = (A1 - A3) / 2 is satisfied. By the above technical means, the risk of the positive electrode piece protruding from the negative electrode piece in the longitudinal direction is reduced, the risk of lithium deposition on the negative electrode piece is reduced, and the safety reliability of the electrochemical apparatus can be improved.

[0011] In one embodiment of the present invention, when viewed from the thickness direction of the negative electrode piece, the lithium replenishment region has striped portions, the dimensions of the striped portions are 0.1 mm to 2 mm along the arrangement direction of the multiple striped portions, and / or the thickness of the striped portions is 0.04 μm to 0.5 μm in the thickness direction of the negative electrode piece. The negative electrode piece having the above characteristics can improve the initial Coulomb efficiency of the negative electrode piece, is advantageous for improving the energy density of the electrochemical apparatus, and is also advantageous for improving the manufacturing efficiency of the lithium replenishment region.

[0012] In one embodiment of the present invention, the material of the lithium replenishment region comprises at least one of lithium carbonate, lithium oxide, lithium nitride, or lithium fluoride. During the lithium replenishment process of the negative electrode piece, the lithium metal is highly reactive and reacts with air, and then reacts in the chemical conversion process of the electrochemical apparatus, so that a lithium-containing compound is formed on the surface of the first negative electrode active material layer, and the main component of the lithium-containing compound comprises at least one of lithium carbonate, lithium oxide, lithium nitride, or lithium fluoride. The negative electrode piece having the above characteristics can improve the initial Coulomb efficiency of the negative electrode piece and is advantageous in improving the energy density of the electrochemical apparatus. Furthermore, it can improve the surface resistance of the negative electrode piece and is advantageous in reducing the risk of short circuits and short-circuit currents. In addition, the material of the lithium replenishment region covering the surface of the negative electrode active material can reduce the risk of solid electrolyte interface film fracture.

[0013] In one embodiment of the present invention, the first negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes a silicon-based material, which is advantageous for improving the energy density of the electrochemical apparatus.

[0014] In one embodiment of the present invention, the electrode assembly has a wound structure, where the width direction is the direction of extension of the short side after the electrode piece has been unfolded, the longitudinal direction is the direction of extension of the long side after the electrode piece has been unfolded, and the electrode piece includes a positive electrode piece and a negative electrode piece. The wound structure is advantageous for large-scale, high-speed manufacturing of electrode assemblies.

[0015] In one embodiment of the present invention, the conditions 0.15 ≤ A4 ≤ 5 and 0.15 ≤ B4 ≤ 1.75 are satisfied. Setting A4 and B4 within these ranges allows for a large and appropriate margin in the longitudinal direction and a small and appropriate margin in the width direction, which is advantageous in improving manufacturing efficiency and meeting manufacturing requirements, further reducing the risk of lithium deposition on the negative electrode piece and reducing the impact on the capacity of the electrochemical apparatus.

[0016] In one embodiment of the present invention, the electrode assembly has a laminated structure, where the width direction is the direction of extension of the short side of the electrode piece, the longitudinal direction is the direction of extension of the long side of the electrode piece, and the electrode piece includes a positive electrode piece and a negative electrode piece. The laminated structure is advantageous for the spatial utilization of the electrode assembly and improves the design capacity of the electrochemical apparatus.

[0017] In one embodiment of the present invention, the conditions 0.15 ≤ A4 ≤ 1.75 and 0.15 ≤ B4 ≤ 1.6 are satisfied. Setting A4 and B4 within these ranges allows for appropriate margins in the longitudinal and width directions, thereby reducing the risk of lithium deposition on the negative electrode piece and minimizing the impact on the capacity of the electrochemical apparatus.

[0018] A second aspect of the present invention provides a method for manufacturing an electrochemical apparatus provided in the first aspect of the present invention, A negative electrode piece is obtained by providing a first negative electrode active material layer on the surface of a negative electrode current collector, and providing a lithium-supplied region and a lithium-unsupplied region in the first negative electrode active material layer. By providing a first positive electrode active material layer on the surface of the positive electrode current collector, a positive electrode piece is obtained. The method involves assembling a negative electrode piece and a positive electrode piece to obtain an electrode assembly, and packaging the electrode assembly to obtain an electrochemical apparatus, wherein the first negative electrode active material layer and the first positive electrode active material layer are facing each other.

[0019] An electrochemical apparatus manufactured by the method provided in a second aspect of the present invention can reduce the risk of lithium deposition on the negative electrode piece and improve the safety reliability of lithium-ion batteries.

[0020] In one embodiment of the present invention, the process of assembling an electrode assembly includes stacking a negative electrode piece and a positive electrode piece to obtain an electrode assembly, or stacking a negative electrode piece and a positive electrode piece and winding them together to obtain an electrode assembly.

[0021] In one embodiment of the present invention, a lithium replenishment region is provided in the first negative electrode active material layer on the surface of the first negative electrode active material layer using at least one of lithium foil or lithium powder. Providing the lithium replenishment region by the above method can improve the initial coulombic efficiency of the negative electrode tab, which is advantageous for increasing the energy density of the electrochemical device.

[0022] A third aspect of the present invention provides an electronic device, which comprises the electrochemical device provided in the first aspect of the present invention. Since the electrochemical device provided by the present invention has excellent safety and reliability, the electronic device provided by the present invention has excellent safety and reliability. [Effects of the Invention]

[0023] The present invention provides an electrochemical device, a method for manufacturing the same, and an electronic device. By providing a lithium unreplenished region in the first negative electrode active material layer in the edge region of the negative electrode tab, the risk of lithium precipitation on the negative electrode tab is reduced. The lithium unreplenished region can occlude more lithium ions from the positive electrode than the lithium replenished region. During the cycling process of the electrochemical device, the local capacity ratio in the edge region of the negative electrode tab increases, and can accommodate more lithium ions from the opposite edge of the positive electrode tab, thereby reducing the risk of lithium precipitation at the edge in the width direction of the negative electrode tab and improving the safety and reliability of the electrochemical device. Of course, implementation of any product or method of the present invention does not necessarily require simultaneous achievement of all of the above advantages. [Brief Description of the Drawings]

[0024] Hereinafter, in order to more clearly describe the technical means of the present invention, the drawings required for the embodiments are briefly described, and it is obvious that the drawings described below are only some embodiments of the present invention.

[0025] [Figure 1] Figure 1 is a schematic structural diagram of an electrode assembly according to an embodiment of the present invention. [Figure 2]Figure 2 is a schematic diagram of a positive electrode piece according to one embodiment of the present invention. [Figure 3] Figure 3 is a schematic diagram of a negative electrode piece according to one embodiment of the present invention. [Figure 4] Figure 4 is a schematic diagram of the positive electrode piece as viewed along the thickness direction according to one embodiment of the present invention. [Figure 5] Figure 5 is a cross-sectional view AA along the thickness direction of the negative electrode piece according to one embodiment of the present invention, and the location of the AA cross-section is shown in Figure 3. [Figure 6] Figure 6 is a schematic diagram of a positive electrode piece viewed along the thickness direction according to another embodiment of the present invention. [Figure 7] Figure 7 is a cross-sectional view AA along the thickness direction of the negative electrode piece according to another embodiment of the present invention, the location of the AA cross-section is shown in Figure 3. [Figure 8] Figure 8 is a scanning electron microscope (SEM) image of the lithium-replenished region of the negative electrode piece fabricated in Example 1-1 of the present invention. [Figure 9] Figure 9 is an SEM image of the lithium-unreplenished region in the edge region along the longitudinal direction (x direction) of the negative electrode piece fabricated in Example 1-1 of the present invention. [Figure 10] Figure 10 is an SEM image of the lithium-containing compound layer on the surface of the negative electrode piece fabricated in Example 1-1 of the present invention. [Modes for carrying out the invention]

[0026] The present invention will be described in more detail below with reference to the drawings and examples in order to further clarify its objectives, technical means, and advantages. It is clear that the examples described are only some, and not all, examples of the present invention. All other examples obtained by those skilled in the art based on the present invention are included within the scope of protection of the present invention.

[0027] In the detailed embodiments of the present invention, a lithium-ion battery is given as an example of an electrochemical apparatus, but the electrochemical apparatus of the present invention is not limited to a lithium-ion battery.

[0028] Electrochemical apparatuses are typically designed so that the area of ​​the negative electrode is larger than that of the positive electrode to reduce the risk of lithium deposition during use. The portion where the negative electrode extends beyond the positive electrode is called the negative electrode edge extension. Since the negative electrode edge extension cannot be subjected to pressure during the chemical formation and capacitance stages of the electrochemical apparatus, the adhesive force between the separator and the negative electrode weakens in this region, and the gap at the interface between the separator and the negative electrode increases. During the electrochemical apparatus cycle, as the electrolyte is consumed, the electrolyte bridge at the negative electrode edge becomes more prone to breaking, leading to lithium deposition problems at the negative electrode edge.

[0029] Furthermore, the electrochemical apparatus undergoes expansion during the cycle process, causing the electrode pieces to stretch in both the width and length directions, resulting in the electrode assembly continuously pressing against the case and causing deformation of the electrochemical apparatus. Therefore, it is necessary to design and secure a certain gap between the electrode assembly and the case. However, since there is a large amount of electrolyte at the edges of the electrode assembly after injection, the content of film-forming additives in the electrolyte at the edges increases, and the film-forming impedance at the edges of the electrode pieces becomes large during the chemical conversion and capacitance stages. As a result, lithium deposition is more likely to occur at the edges of the negative electrode piece during the cycle process.

[0030] To increase the capacity of an electrochemical apparatus, the initial Coulomb efficiency of the negative electrode is typically improved by supplementing the negative electrode with lithium.

[0031] In view of the above, a first aspect of the present invention provides an electrochemical apparatus, which, as shown in Figures 1, 2, and 3, comprises an electrode assembly 10, the electrode assembly 10 including a positive electrode piece 11 and a negative electrode piece 12, the schematic configuration of the positive electrode piece 11 as seen along the thickness direction is shown in Figure 4, and the AA cross section of the negative electrode piece 12 shown in Figure 3 along its own thickness direction is shown in Figure 5. The positive electrode piece 11 includes a positive electrode current collector 110 and a first positive electrode active material layer 111 provided on the surface of the positive electrode current collector 110, the negative electrode piece 12 includes a negative electrode current collector 120 and a first negative electrode active material layer 121 provided on the surface of the negative electrode current collector 120, the first negative electrode active material layer 121 includes a lithium replenished region 122 and a lithium unreplenished region 123, the lithium unreplenished region 123 is a region in the first negative electrode active material layer 121 whose area does not overlap with the lithium replenished region 122. Referring to Figure 3, if the width (y-direction) dimension of the first negative electrode active material layer 121 is B1 mm, the width (y-direction) dimension of the first positive electrode active material layer 111 is B2 mm, and the distance between one edge 1211 extending along the longitudinal direction (x-direction) of the first negative electrode active material layer 121 and the adjacent edge 1221 of the lithium replenishment region extending along the longitudinal direction (x-direction) is B4 mm, then the condition 0.15 ≤ B4 ≤ 1 / 2 × (B1 - B2) + 1 is satisfied.

[0032] The present invention achieves uniform lithium replenishment in the normal region of the negative electrode piece 12 without replenishing lithium at the edge of the negative electrode piece 12 by adjusting the amount of lithium replenishment in different regions of the surface of the negative electrode piece 12. Because lithium replenishment is not performed at the edge of the negative electrode piece 12, the local capacity ratio at that location is large, and more lithium ions from the positive electrode piece 11 can be accommodated. In electrochemical apparatuses, during the formation and capacity stages, lithium ions from the opposing positive electrode piece 11 are received at the edge of the negative electrode piece 12 to form a solid electrolyte membrane and silicate, etc. These lithium ions become inert lithium and cannot return to the positive electrode piece 11, resulting in a decrease in reversible lithium ions at the edge of the positive electrode piece 11. Therefore, even if the electrolyte bridge is broken at the edge of the negative electrode piece 12, or if the film deposition impedance at the edge of the negative electrode piece 12 becomes large, the capacitance ratio at this position is large and there is little active lithium at the edge of the opposing positive electrode piece 11. As a result, the reception of lithium ions from the edge of the opposing positive electrode piece 11 can be completed at the edge of the negative electrode piece 12, thus reducing the risk of lithium deposition occurring at the edge of the negative electrode piece 12 during the cycle process.

[0033] In one embodiment of the present invention, as shown in Figure 3, when the longitudinal dimension (x-direction) of the first negative electrode active material layer 121 is A1 mm, the longitudinal dimension (x-direction) of the first positive electrode active material layer 111 is A2 mm, and the distance between one edge 1212 extending along the width direction (y-direction) of the first negative electrode active material layer 121 and the adjacent edge 1222 of the lithium replenishment region extending along the width direction (y-direction) is A4 mm, the following condition is met: 0.15 ≤ A4 ≤ 1 / 2 × (A1 - A2) + 1. By adjusting A4 to within the above range, the risk of lithium deposition at the longitudinal edge of the negative electrode piece 12 can be reduced, and the safety reliability of the electrochemical apparatus can be improved.

[0034] In one embodiment of the present invention, when the width (y-direction) dimension of the lithium replenishment area 122 is B3 mm, the condition B4 = (B1 - B3) / 2 is satisfied. By the above technical means, the risk of the positive electrode piece 11 exceeding the negative electrode piece 12 in the width direction is reduced, the risk of lithium deposition on the negative electrode piece 12 is reduced, and the safety reliability of the electrochemical apparatus can be improved.

[0035] In one embodiment of the present invention, when the longitudinal dimension (x-direction) of the lithium replenishment region 122 is A3 mm, the condition A4 = (A1 - A3) / 2 is satisfied. By the above technical means, the risk of the positive electrode piece 11 exceeding the negative electrode piece 12 in the longitudinal direction is reduced, the risk of lithium deposition on the negative electrode piece 12 is reduced, and the safety reliability of the electrochemical apparatus can be improved.

[0036] In one embodiment of the present invention, the electrode assembly 10 has a wound structure and satisfies 0.15 ≤ A4 ≤ 5 and 0.15 ≤ B4 ≤ 1.75. By adjusting the dimensions of the lithium-unreplenished region 123 to satisfy the above relationship, the risk of lithium deposition on the negative electrode piece 12 can be reduced, improving the safety reliability of the electrochemical apparatus, and reducing the impact on the capacity of the electrochemical apparatus due to the dimensions of the lithium-unreplenished region 123 being too large.

[0037] In one embodiment of the present invention, the electrode assembly 10 has a stacked structure and satisfies 0.15 ≤ A4 ≤ 1.75 and 0.15 ≤ B4 ≤ 1.6. By adjusting the dimensions of the lithium-unreplenished region 123 to satisfy the above relationship, the impact on the capacity of the electrochemical apparatus due to the dimensions of the lithium-unreplenished region 123 being too large can be further reduced.

[0038] In one embodiment of the present invention, a schematic diagram of the positive electrode piece 11 as viewed along the thickness direction is shown in Figure 6, and a cross-sectional view AA along the thickness direction of the negative electrode piece (as shown in Figure 3) is shown in Figure 7. The positive electrode piece 11 includes a positive electrode current collector 110 and a first positive electrode active material layer 111 provided on one surface of the positive electrode current collector 110, and the negative electrode piece 12 includes a negative electrode current collector 120 and a first negative electrode active material layer 121 provided on one surface of the negative electrode current collector 120, thereby achieving the objectives of the present invention.

[0039] In one embodiment, when viewed from the thickness direction (z direction) of the negative electrode piece 12, the lithium replenishment region 122 has striped portions, and along the arrangement direction of the multiple striped portions, the dimensions of the striped portions are 0.1 mm to 2 mm, and / or in the thickness direction of the negative electrode piece 12, the thickness of the striped portions is 0.04 μm to 0.5 μm. The negative electrode piece having the above characteristics can improve the initial Coulomb efficiency of the negative electrode piece 12 and is advantageous in improving the energy density of the electrochemical apparatus. Specifically, in one embodiment, in the first direction, the width of the striped portions is 0.1 mm to 2 mm, and in the thickness direction, the thickness of the striped portions is 0.04 μm to 0.5 μm. In one embodiment, in the first direction, the width of the striped portions is 0.1 mm to 2 mm. In one embodiment, in the thickness direction, the thickness of the striped portions is 0.04 μm to 0.5 μm.

[0040] It should be understood that the striped portion is a lithium strip with stripe gaps formed during the rolling process of lithium metal when lithium is replenished using metallic lithium foil. During the process of the lithium foil being combined with the negative electrode piece 12, the lithium strip with stripe gaps formed as described above can be maintained, so the striped portion can be seen from the thickness direction (z direction) of the negative electrode piece 12. After the negative electrode piece 12 and positive electrode piece 11 are assembled in the electrochemical apparatus after lithium replenishment, lithium metal is absorbed into the negative electrode piece 12, and the striped portion on the surface of the negative electrode piece 12 remains as is during the subsequent chemical conversion and capacitance processing. After the electrochemical apparatus undergoes a cycle process, the lithium replenishment region 122 of the negative electrode piece 12 has a striped portion as shown in Figure 8, while the lithium unreplenished region 123 at the edge region of the negative electrode piece 12 does not have a striped portion as shown in Figure 9.

[0041] In one embodiment of the present invention, the material of the lithium replenishment region 122 includes at least one of lithium carbonate, lithium oxide, lithium nitride, and lithium fluoride. In the process of lithium replenishment for the negative electrode tab 12, since lithium metal has high activity, it reacts with air (for example, oxygen gas and trace moisture) and reacts with fluorine-containing substances in the electrolyte during the formation process of the electrochemical device, so a lithium-containing compound is formed on the surface of the first negative electrode active material layer 121, and the main component of the formed lithium-containing compound includes at least one of lithium carbonate, lithium oxide, lithium nitride, and lithium fluoride. After the electrode assembly 10 is assembled and the electrolyte is injected, lithium metal rapidly reacts with the negative electrode active material, while 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 tab 12. A lithium-containing compound layer is formed in the lithium replenishment region 122 on the surface of the negative electrode active material. Referring to the layered structure shown between the two black dotted lines in FIG. 10, the thickness of the lithium-containing compound layer is 0.04 μm to 0.5 μm. The negative electrode tab 12 having the above features can improve the initial coulombic efficiency of the negative electrode tab 12, which is advantageous for improving the energy density of the electrochemical device. In addition, the resistance on the surface of the negative electrode tab 12 can be increased, which is also advantageous for reducing the risk of short circuit and the short circuit current. Furthermore, the material of the lithium replenishment region 122 covering the surface of the negative electrode active material can reduce the risk of solid electrolyte interface film breakage.

[0042] In one embodiment of the present invention, the first negative electrode active material layer 121 includes a negative electrode active material, and the negative electrode active material includes a silicon-based material. The silicon-based material is silicon, a silicon oxide compound (SiO x , 0<x≤2), at least one of silicon alloys, or silicon-carbon composites. The negative electrode active material of the present invention further includes graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, lithium titanate Li4Ti5O with spinel structure 12It may further contain at least one of the following: Li-Al alloy or metallic lithium. Selecting a material within the above range is advantageous for improving the energy density of the electrochemical apparatus.

[0043] It should be understood that a wound electrode assembly typically has a long side and a short side after the electrode pieces have been unfolded. In one embodiment of the present invention, if the electrode assembly is a wound structure, the width direction is the direction in which the short side extends after the electrode pieces have been unfolded, and the longitudinal direction is the direction in which the long side extends after the electrode pieces have been unfolded. The electrode pieces of the present invention include a positive electrode piece 11 and a negative electrode piece 12.

[0044] It should be understood that in a laminated electrode assembly, the electrode pieces are typically arranged in layers. In one embodiment of the present invention, the electrode assembly is a laminated structure, where the width direction is the direction of the extension of the short side of the electrode piece, and the longitudinal direction is the direction of the extension of the long side of the electrode piece. The electrode piece includes a positive electrode piece 11 and a negative electrode piece 12.

[0045] In one embodiment of the present invention, in a laminated electrode assembly, if the dimensions of each side of the electrode pieces are the same, the width direction is the direction in which one side of the electrode piece extends, and the longitudinal direction is the direction perpendicular to the width direction in the plane in which the electrode pieces are located.

[0046] In the present invention, the electrochemical apparatus is not particularly limited and may include any apparatus that causes an electrochemical reaction. In one embodiment of the present invention, the electrochemical apparatus may include, 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 invention, the structure of the electrode assembly of the lithium-ion battery of the present invention includes a wound structure or a stacked structure. The structure of the lithium-ion battery of the present invention includes, but is not limited to, a soft-pack type lithium-ion battery, a prismatic hard-shell battery, a cylindrical hard-shell battery, etc.

[0047] In the present invention, the negative electrode current collector 120 may not be particularly limited as long as the objectives of the present invention are achieved. For example, the negative electrode current collector 120 may include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or a composite current collector. In the present invention, the thickness of the negative electrode current collector 120 is not particularly limited as long as the objectives of the present invention are achieved. For example, the thickness of the negative electrode current collector 120 is 4 μm to 10 μm. In the present invention, the first negative electrode active material layer 121 may be provided on one surface in the thickness direction of the negative electrode current collector 120, or on two surfaces in the thickness direction of the negative electrode current collector 120. Here, "surface" may refer to the entire area of ​​the negative electrode current collector 120, or a part of the area of ​​the negative electrode current collector 120, but is not particularly limited as long as the objectives of the present invention are achieved.

[0048] In the present invention, the negative electrode current collector 120 has a first negative electrode active material layer 121 on its surface, or a functional layer is further included between the negative electrode current collector 120 and the first negative electrode active material layer 121. For example, the functional layer includes, but is not limited to, a conductive adhesive layer. Here, the conductive adhesive layer may include a conductive agent and a binder.

[0049] In the present invention, the thickness of the first negative electrode active material layer 121 is not particularly limited, as long as the objectives of the present invention can be achieved. For example, the thickness of the first negative electrode active material layer on one side is 30 μm to 160 μm.

[0050] In the present invention, the conductive agent is not particularly limited as long as it can achieve the objectives of the present invention, and may, for example, include at least one of carbon-based materials, metallic materials, or conductive polymers. The carbon-based material includes at least one selected from the group consisting of natural graphite, artificial graphite, conductive carbon black, acetylene black, Ketjen black, or carbon fibers. The metallic material may, but is not limited to, metal powder and / or metal fibers, and the metal may, specifically, include at least one of copper, nickel, aluminum, and silver. The conductive polymer may, but is not limited to, polyphenylene derivatives, polyaniline, polythiophene, polyacetylene, and polypyrrole.

[0051] In the present invention, the binder is not particularly limited as long as it can achieve the objectives of the present invention. The binder may, but is not limited to, at least one of the following: polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylic acid, styrene-butadiene rubber, acrylic (esterified) styrene-butadiene rubber, epoxy resin, or nylon.

[0052] In the present invention, the positive electrode current collector 110 is not particularly limited as long as it can achieve the objectives of the present invention. For example, the positive electrode current collector 110 may include aluminum foil, aluminum alloy foil, or a composite current collector. In the present invention, the thickness of the positive electrode current collector 110 is not particularly limited as long as it can achieve the objectives of the present invention. For example, the thickness of the positive electrode current collector 110 is preferably 5 μm to 20 μm, and preferably 6 μm to 18 μm.

[0053] The first positive electrode active material layer 111 according to the present invention may contain a positive electrode active material. In the present invention, the type of positive electrode active material is not particularly limited as long as the objectives of the present invention can be achieved. For example, the positive electrode active material may contain at least one of the following: lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium iron phosphate, lithium-rich manganese-based material, lithium cobalt oxide, lithium manganese oxide, or lithium iron manganese phosphate. In the present invention, the positive electrode active material may contain a nonmetallic element, and the nonmetallic element may contain at least one of the following: fluorine, phosphorus, boron, chlorine, silicon, or sulfur, and these elements can further improve the stability of the positive electrode active material.

[0054] In the present invention, the thickness of the first positive electrode active material layer 111 is not particularly limited, as long as the objectives of the present invention can be achieved. For example, the thickness of the first positive electrode active material layer 111 on one side is 30 μm to 120 μm.

[0055] In the present invention, the first positive electrode active material layer 111 may be provided on one surface in the thickness direction of the positive electrode current collector 110, or on two surfaces in the thickness direction of the positive electrode current collector 110. Here, "surface" may refer to the entire area of ​​the positive electrode current collector 110, or a part of the area of ​​the positive electrode current collector 110, but is not particularly limited as long as the objective of the present invention is achieved.

[0056] In the present invention, the separator and electrolyte are not particularly limited as long as they achieve the objective of the present invention, and those skilled in the art may select them according to the actual situation.

[0057] A second aspect of the present invention provides a method for manufacturing an electrochemical apparatus provided in the first aspect of the present invention, A negative electrode piece 12 is obtained by providing a first negative electrode active material layer 121 on the surface of the negative electrode current collector 120, and providing a lithium-replenished region 122 and a lithium-unreplenished region 123 in the first negative electrode active material layer 121. By providing a first positive electrode active material layer 111 on the surface of the positive electrode current collector 110, a positive electrode piece 11 is obtained. The method involves assembling a negative electrode piece 12 and a positive electrode piece 11 to obtain an electrode assembly 10, and packaging the electrode assembly 10 to obtain an electrochemical apparatus, wherein the first negative electrode active material layer 121 and the first positive electrode active material layer 111 are facing each other.

[0058] In the present invention, the method for providing the first negative electrode active material layer 121 on the surface of the negative electrode current collector 120 is not particularly limited. For example, one method is to apply a negative electrode slurry to the surface of the negative electrode current collector 120 to form the first negative electrode active material layer 121. In the present invention, the method for providing the first positive electrode active material layer 111 on the surface of the positive electrode current collector 110 is not particularly limited. For example, one method is to apply a positive electrode slurry to the surface of the positive electrode current collector 110 to form the first positive electrode active material layer 111.

[0059] In the present invention, the method for adjusting the dimensions of the lithium-replenished region 122 and the lithium-unreplenished region 123 is not particularly limited, and known methods in the art may be used. For example, tape may be applied to the area on the surface of the negative electrode piece 12 that does not require lithium replenishment, and the dimensions of the tape can be adjusted according to the dimensions of the lithium-unreplenished region 123 to be designed. Then, lithium foil is compounded onto the surface of the negative electrode piece 12 and subjected to a rolling process, and after lithium replenishment is completed, the tape is removed to obtain a negative electrode piece 12 in which lithium has been replenished in a part of the area.

[0060] An electrochemical apparatus manufactured by the method provided in a second aspect of the present invention can reduce the risk of lithium deposition on the negative electrode piece 12 and improve the safety reliability of the electrochemical apparatus.

[0061] In one embodiment of the present invention, the process of assembling the electrode assembly 10 includes stacking the negative electrode piece 12 and the positive electrode piece 11 to obtain the electrode assembly 10, or stacking the negative electrode piece 12 and the positive electrode piece 11 and winding them together to obtain the electrode assembly 10.

[0062] In the present invention, the electrode assembly 10 is packaged to obtain an electrochemical apparatus, and in the present invention, the packaging process is not particularly limited as long as it achieves the objectives of the present invention.

[0063] In one embodiment of the present invention, a lithium replenishment region 122 is provided on the surface of the first negative electrode active material layer 121 using at least one of lithium foil or lithium powder. Providing the lithium replenishment region 122 in the above manner is advantageous in improving the initial Coulomb efficiency of the negative electrode piece 12 and improving the energy density of the electrochemical apparatus.

[0064] In the present invention, the method for replenishing lithium is not particularly limited as long as it achieves the objective of the present invention, and a person skilled in the art may select a method according to the actual situation. For example, the lithium foil may be rolled to a thickness of the order of microns in a drying chamber (ambient humidity <1.7%), and then the surface of the negative electrode piece 12 may be combined and rolled.

[0065] A third aspect of the present invention provides an electronic device comprising an electrochemical device provided in the first aspect of the present invention. Since the electrochemical device provided by the present invention has excellent safety reliability, the electronic device provided by the present invention has excellent safety reliability.

[0066] In the present invention, the electronic device is not particularly limited and may be any 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, a portable copier, a portable printer, a stereo headset, a video recorder, an LCD television, a portable cleaner, a portable CD player, a MiniDisc, a transceiver, an electronic organizer, a calculator, a memory card, a portable tape recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, an electric assist bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, a power tool, a strobe, a camera, a large household storage battery, or a lithium-ion capacitor.

[0067] Embodiments of the present invention will be described in more detail below with reference to examples and comparative examples. Various tests and evaluations will be carried out according to the methods described below. Unless otherwise specified, "parts" and "%" are based on mass.

[0068] Measurement method and device Measurement of the morphology of the negative electrode piece: The negative electrode pieces are decomposed in a drying chamber (humidity <1.7%) after cycling, washed three times with dimethyl carbonate (DMC), dried, and their morphology is observed using a scanning electron microscope (SEM). SEM images are taken, and the width of the stripe portion is measured.

[0069] Measurement of the morphology of a cross-section of the negative electrode: After decomposition, the negative electrode fragments are polished using argon ions to prepare samples. The cross-sectional morphology is then photographed using a scanning electron microscope (SEM), and the thickness of the stripe portion and the thickness of the lithium-containing compound layer on the surface of the negative electrode fragments are measured.

[0070] Cycle measurement: Environmental temperature: 25±5℃ Cycle measurement flow: Charge the lithium-ion battery to full capacity at the maximum rated current, let it stand for 5 minutes, discharge it at a constant current of 0.5C (rate) down to 3.0V, repeat the above charge-discharge process 500 times, and then charge it to full capacity at the maximum rated current for another 500 cycles. After that, disassemble each lithium-ion battery and observe the lithium deposition status on the edge of the negative electrode piece.

[0071] Assessment of the degree of lithium deposition: The negative electrode piece is disassembled after cycling in a drying chamber (humidity <1.7%), and the lithium deposition status is photographed and recorded on the edge of the negative electrode piece. If no lithium deposition is found or the lithium deposition area is <2%, it is called "no lithium deposition." If the lithium deposition area is between 2% and 20%, it is called "mild lithium deposition." If the lithium deposition area is >20%, it is called "severe lithium deposition." Here, the percentage of the lithium deposition area is calculated based on the area of ​​one side of the negative electrode piece.

[0072] Measurement of capacity: The lithium-ion battery is charged at a rate of 0.5C in a 25°C atmosphere until the upper voltage reaches 4.2V. Then, it is discharged at a constant current of 0.2C until the final voltage reaches 2.8V. The initial discharge capacity at 0.2C is calculated as the capacity of the lithium-ion battery.

[0073] Example 1-1 <Fabrication of negative electrode piece> Graphite and silicon oxygen compounds (SiO2) as negative electrode active materials x , x=1), carboxymethylcellulose sodium and styrene-butadiene rubber are mixed in a mass ratio of 96.7:10:1.3:1.0, then deionized water is added as a solvent to prepare a negative electrode slurry with a solid content of 70 wt%, and the mixture is stirred until homogeneous. The negative electrode slurry is uniformly applied to one surface of a copper foil negative electrode current collector with a thickness of 10 μm, and dried at 110°C to obtain a negative electrode piece with a first negative electrode active material layer applied to one side, with a coating layer thickness of 150 μm. The above steps are then repeated on the other surface of the negative electrode piece to obtain a negative electrode piece with the first negative electrode active material layer applied to both sides. After coating is complete, the negative electrode piece is cold-pressed and cut for use. Here, the dimension A1 in the x-direction of the first negative electrode active material layer is 1258 mm, and the dimension B1 in the y-direction is 73.8 mm.

[0074] Tape is applied to the area of ​​the negative electrode piece surface that does not require lithium replenishment, and the dimensions of the tape may be adjusted according to the dimensions of the lithium-unreplenished area designed; in other words, B4 is adjusted by adjusting the dimensions of the tape. Then, the lithium foil is rolled down to a thickness of the order of microns (2 μm) in a drying chamber (ambient humidity < 1%), and then rolled down in combination with the surface of the negative electrode piece prepared as described above, the tape on the surface of the negative electrode piece is removed, and a negative electrode piece with lithium replenished except for the edge area is obtained. The dimensions of the lithium-replenished area A3 are 1258 mm, B3 is 73.6 mm, the dimensions of the lithium-unreplenished area in the edge region of the negative electrode piece A4 are 0 mm, and B4 is 0.15 mm. The compressed density of the negative electrode piece is 1.76 g / cm³ 3 That is the case.

[0075] <Preparation of positive electrode piece> Lithium cobalt oxide (LiCoO2) as the positive electrode active material, conductive carbon black and polyvinylidene fluoride (PVDF) as conductive agents were mixed in a mass ratio of 97:1.4:1.6, and N-methylpyrrolidone (NMP) was added as a solvent to prepare a positive electrode slurry with a solid content of 75 wt%, which was stirred until homogeneous. The positive electrode slurry was uniformly applied to one surface of an aluminum foil, which served as a positive electrode current collector with a thickness of 10 μm, and dried at 110°C to obtain a positive electrode piece with the positive electrode active material coated on one side, with a first positive electrode active material layer thickness of 110 μm. Subsequently, the first positive electrode active material layer was applied to the other surface of the positive electrode piece, and a positive electrode piece with the positive electrode active material coated on both sides was obtained in the same manner as in the above step. After coating was completed, the positive electrode piece was cold-pressed and cut for use. Here, the x-direction dimension A2 of the first positive electrode active material layer is 1250 mm, and the y-direction dimension B2 is 72.3 mm. The compressed density of the positive electrode piece is 4.15 g / cm³. 3 That is the case.

[0076] <Preparation of Electrolyte> In a glove box under a dry argon gas atmosphere, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and ethyl propionate (EP) were mixed as organic solvents in a mass ratio of EC:PC:DEC:EP = 3:1:3:3. Then, lithium hexafluorophosphate (LiPF6) was added to the organic solvents as a lithium salt and dissolved, and the mixture was stirred until homogeneous to obtain an electrolyte with a lithium salt concentration of 1 mol / L.

[0077] <Separator fabrication> A slurry was prepared by mixing PVDF and alumina ceramics in a mass ratio of 9:1, adding deionized water as a solvent, and stirring until homogeneous. The slurry was then uniformly applied to one surface of a 15 μm thick polyethylene film substrate and dried to obtain a separator.

[0078] <Manufacturing of lithium-ion batteries> The positive electrode piece, separator, and negative electrode piece, prepared as described above, were stacked in order and wound up to obtain an electrode assembly, with the separator interposed between the positive electrode piece and the negative electrode piece to provide isolation. The electrode assembly was placed in an aluminum plastic film packaging bag, left in a vacuum oven at 85°C for 12 hours to remove moisture, and the electrolyte prepared as described above was injected. After vacuum packaging, standing, formation (constant current charging at 0.02C up to 3.5V, then constant current charging at 0.1C up to 3.9V), shaping, and capacity processing were performed to obtain a lithium-ion battery with a designed battery capacity of 4614mAh.

[0079] Examples 1-2 to 1-12 The procedure was the same as in Example 1-1, except that the dimensional parameters for the lithium-ion battery were adjusted according to Table 1.

[0080] Examples 2-1 to 2-12 The procedure was the same as in Example 1-1, except that the dimensional parameters for the lithium-ion battery were adjusted according to Table 2.

[0081] Example 3-1 In the <fabrication of the negative electrode piece>, the dimension A1 in the x-direction of the first negative electrode active material layer was 94.1 mm, the dimension B1 in the y-direction was 42.5 mm, the dimension A3 of the lithium replenishment region was 94.1 mm, B3 was 42.1 mm, and the dimension B4 of the lithium unreplenished region at the edge region of the negative electrode piece was 0.2 mm. In the <fabrication of the positive electrode piece>, the dimension A2 in the x-direction of the first positive electrode active material layer was 92.6 mm, the dimension B2 in the y-direction was 41.3 mm, and the <fabrication of the lithium-ion battery> was the same as in Example 1-1, except that it differed from Example 1.

[0082] <Manufacturing of lithium-ion batteries> The positive electrode piece, separator, and negative electrode piece were stacked in order so that the separator was interposed between the positive electrode piece and the negative electrode piece to provide isolation. The four corners of the entire stacked structure were secured with tape, and the stack was placed in an aluminum plastic film. After top sealing, liquid injection, and packaging, a lithium-ion battery was obtained.

[0083] The dimensional parameters of the fabricated lithium-ion battery are shown in Table 3, and the designed battery capacity is 2926mAh.

[0084] Examples 3-2 to 3-11 The procedure was the same as in Example 3-1, except that the dimensional parameters for the lithium-ion battery were adjusted according to Table 3.

[0085] Examples 4-1 to 4-11 The procedure was the same as in Example 3-1, except that the dimensional parameters for the lithium-ion battery were adjusted according to Table 4.

[0086] Comparative Examples 1 to 3 The procedure was the same as in Example 1-1, except that the dimensional parameters for the lithium-ion battery were adjusted according to Table 1.

[0087] Comparative Example 4 The procedure was the same as in Example 1-1, except that the dimensional parameters for the lithium-ion battery were adjusted according to Table 2.

[0088] Comparative Examples 5 to 7 The procedure was the same as in Example 3-1, except that the dimensional parameters for the lithium-ion battery were adjusted according to Table 3.

[0089] Comparative Examples 8-9 The procedure was the same as in Example 3-1, except that the dimensional parameters for the lithium-ion battery were adjusted according to Table 4.

[0090] The parameters and characteristics measured for Examples 1-1 to 1-12 and Comparative Examples 1 to 3 are shown in Table 1.

[0091] [Table 1]

[0092] As can be seen from Examples 1-1 to 1-12, Comparative Example 2, and Comparative Example 3, by adjusting B4 within the scope of the present invention, as the dimensions of the lithium-unfilled region provided in the edge region along the x-direction of the negative electrode piece increase, the local capacity ratio of the edge region along the x-direction of the negative electrode piece also increases further, allowing for effective accommodation of lithium ions from the edge of the opposing positive electrode piece. This improves the problem of lithium deposition in the edge region along the x-direction of the negative electrode piece, reduces the risk of lithium deposition on the negative electrode piece, and thus improves the safety and reliability of the lithium-ion battery.

[0093] As can be seen from Examples 1-1 to 1-12 and Comparative Example 1, as the area of ​​the lithium-unfilled region increases, the local capacity ratio of that region also increases. Because the initial Coulomb efficiency of silicon as the negative electrode active material is low, active lithium ions from the positive electrode are consumed during the initial charge and discharge, reducing the amount of lithium ions available on the positive electrode piece, and the lithium-ion battery capacity tends to decrease. However, if the area of ​​the lithium-unfilled region is too large (for example, Comparative Example 1), the phenomenon of lithium deposition does not occur in the edge region along the x-direction of the negative electrode piece, but the degree to which the lithium-ion battery capacity decreases is too great, which is detrimental to improving the capacity performance characteristics of the lithium-ion battery. As can be seen from this, adjusting B4 within the scope of the present invention makes it possible to obtain a lithium-ion battery with excellent capacity performance characteristics.

[0094] The parameters and characteristics measured for Examples 2-1 to 2-12, Comparative Example 2, and Comparative Example 4 are shown in Table 2.

[0095] [Table 2]

[0096] As can be seen from Examples 2-1 to 2-12 and Comparative Example 2, by coordinating A4 and B4 within the scope of the present invention, as the dimensions of the lithium-unfilled region in the edge region along the x and y directions of the negative electrode piece increase, the local capacity ratio in the edge region along the x and y directions of the negative electrode piece also increases further, allowing for effective accommodation of lithium ions from the edge of the opposing positive electrode piece. This improves the problem of lithium deposition in the edge region along the x and y directions of the negative electrode piece, reduces the risk of lithium deposition on the negative electrode piece, and thus improves the safety and reliability of the lithium-ion battery.

[0097] As can be seen from Examples 2-1 to 2-12 and Comparative Example 4, the capacity of the lithium-ion battery tends to decrease as the area of ​​the lithium-unfilled region increases. However, if the area of ​​the lithium-unfilled region is too large (for example, Comparative Example 4), the phenomenon of lithium deposition does not occur in the edge regions along the x and y directions of the negative electrode piece, but the degree to which the lithium-ion battery capacity decreases is too great, which is detrimental to improving the capacity performance characteristics of the lithium-ion battery. As can be seen from this, by coordinating A4 and B4 within the scope of the present invention, a lithium-ion battery with excellent capacity performance characteristics can be obtained.

[0098] The parameters and characteristics measured for Examples 3-1 to 3-11 and Comparative Examples 5 to 7 are shown in Table 3.

[0099] [Table 3]

[0100] As can be seen from Examples 3-1 to 3-11, Comparative Example 6, and Comparative Example 7, by adjusting B4 within the scope of the present invention, as the size of the lithium-unfilled region provided in the edge region along the x-direction of the negative electrode piece increases, the local capacity ratio of the edge region along the x-direction of the negative electrode piece increases further, allowing lithium ions from the edge of the opposing positive electrode piece to be effectively accommodated. This improves the lithium deposition problem in the edge region along the x-direction of the negative electrode piece, reduces the risk of lithium deposition on the negative electrode piece, and thus improves the safety and reliability of the lithium-ion battery.

[0101] As can be seen from Examples 3-1 to 3-11 and Comparative Example 5, the capacity of the lithium-ion battery tends to decrease as the area of ​​the lithium-unfilled region increases. However, if the area of ​​the lithium-unfilled region is too large (for example, Comparative Example 5), the phenomenon of lithium deposition does not occur in the edge region along the x-direction of the negative electrode piece, but the degree to which the lithium-ion battery capacity decreases is too great, which is detrimental to improving the capacity performance characteristics of the lithium-ion battery. As can be seen from this, adjusting B4 within the range of the present invention makes it possible to obtain a lithium-ion battery with excellent capacity performance characteristics.

[0102] The parameters and characteristics measured for Examples 4-1 to 4-11, Comparative Example 6, Comparative Example 8, and Comparative Example 9 are shown in Table 4.

[0103] [Table 4]

[0104] As can be seen from Examples 4-1 to 4-11, Comparative Example 6, and Comparative Example 9, by coordinating A4 and B4 within the scope of the present invention, as the dimensions of the lithium-unfilled region provided in the edge region along the x-direction of the negative electrode piece increase, the local capacity ratio of the edge region along the x-direction of the negative electrode piece also increases further, enabling effective accommodation of lithium ions from the edge of the opposing positive electrode piece. This improves the lithium deposition problem in the edge region along the x-direction of the negative electrode piece, reduces the risk of lithium deposition on the negative electrode piece, and thus improves the safety and reliability of the lithium-ion battery.

[0105] As can be seen from Examples 4-1 to 4-11 and Comparative Example 8, the capacity of the lithium-ion battery tends to decrease as the area of ​​the lithium-unfilled region increases. However, if the area of ​​the lithium-unfilled region is too large (for example, Comparative Example 8), the phenomenon of lithium deposition does not occur in the edge regions along the x and y directions of the negative electrode piece, but the degree to which the lithium-ion battery capacity decreases is too great, which is detrimental to improving the capacity performance characteristics of the lithium-ion battery. As can be seen from this, by coordinating A4 and B4 within the scope of the present invention, a lithium-ion battery with excellent capacity performance characteristics can be obtained.

[0106] As described above, the technical means provided in this invention can effectively reduce the risk of lithium deposition on the negative electrode piece, improve the safety and reliability of lithium-ion batteries, and improve the energy density of lithium-ion batteries while maintaining excellent cycle characteristics.

[0107] The above describes only preferred embodiments of the present invention and does not limit it. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should all be within the scope of protection of the present invention.

Claims

1. An electrochemical apparatus comprising an electrode assembly, the electrode assembly comprising a positive electrode piece and a negative electrode piece, the positive electrode piece comprising a positive electrode current collector and a first positive electrode active material layer provided on the surface of the positive electrode current collector, the negative electrode piece comprising a negative electrode current collector and a first negative electrode active material layer provided on the surface of the negative electrode current collector, the first negative electrode active material layer comprising a lithium-supplied region and a lithium-unsupplied region, the lithium-unsupplied region being a region of the first negative electrode active material layer whose area does not overlap with that of the lithium-supplied region. The width dimension of the first negative electrode active material layer is B １ Let the dimension of the first positive electrode active material layer be mm, and the dimension of the width direction be B ２ Let it be mm, The distance between one edge extending along the longitudinal direction in the first negative electrode active material layer and the adjacent edge of the lithium replenishment region extending along the longitudinal direction is B. ４ When set to mm, 0.15 ≤ B ４ ≤ 1 / 2 × (B １ -B ２ ) + 1 satisfying, Electrochemical apparatus.

2. The longitudinal dimension of the first negative electrode active material layer is A １ Let the length be mm, and the longitudinal dimension of the first positive electrode active material layer be A ２ Let it be mm, When the distance between one edge extending along the width direction in the first negative electrode active material layer and the adjacent edge of the lithium replenishment region extending along the width direction is A ４ mm, 0.15 ≦ A ４ ≦ 1 / 2 × (A １ - A ２ ) + 1 is satisfied, The electrochemical apparatus according to claim 1.

3. The width dimension of the lithium replenishment area is B ３ When set to mm, B ４ = (B １ -B ３ ) / 2 satisfies, The electrochemical apparatus according to claim 1.

4. The longitudinal dimension of the lithium replenishment area is A ３ When set to mm, A ４ = (A １ -A ３ ) / 2 satisfies, The electrochemical apparatus according to claim 2.

5. When viewed from the thickness direction of the negative electrode piece, the lithium replenishment region has a striped portion. Along the direction of arrangement of multiple stripe portions, the dimensions of the stripe portions are 0.1 mm to 2 mm, and / or In the thickness direction of the negative electrode piece, the thickness of the stripe portion is 0.04 μm to 0.5 μm. The electrochemical apparatus according to claim 1.

6. The material of the lithium-replenished region includes at least one of lithium carbonate, lithium oxide, lithium nitride, or lithium fluoride. The electrochemical apparatus according to claim 1.

7. 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 apparatus according to claim 1.

8. The electrode assembly has a wound structure, the width direction is the direction of the extension of the short side after the electrode piece is unfolded, the longitudinal direction is the direction of the extension of the long side after the electrode piece is unfolded, and the electrode piece includes a positive electrode piece and a negative electrode piece. The electrochemical apparatus according to claim 2.

9. 0.15 ≤ A ４ The condition ≤ 5 is satisfied, and 0.15 ≤ B ４ Satisfying ≤ 1.75, The electrochemical apparatus according to claim 8.

10. The electrode assembly has a laminated structure, the width direction is the direction in which the short side of the electrode piece extends, the longitudinal direction is the direction in which the long side of the electrode piece extends, and the electrode piece includes a positive electrode piece and a negative electrode piece. The electrochemical apparatus according to claim 2.

11. 0.15 ≤ A ４ The condition ≤ 1.75 is satisfied, and 0.15 ≤ B ４ Satisfying ≤ 1.6, The electrochemical apparatus according to claim 10.

12. A method for manufacturing an electrochemical apparatus according to any one of claims 1 to 11, The negative electrode piece is obtained by providing the first negative electrode active material layer on the surface of the negative electrode current collector and providing a lithium-supplied region and a lithium-unsupplied region in the first negative electrode active material layer. The positive electrode piece is obtained by providing the first positive electrode active material layer on the surface of the positive electrode current collector, The method involves assembling the negative electrode piece and the positive electrode piece to obtain the electrode assembly, and packaging the electrode assembly to obtain the electrochemical apparatus, wherein the first negative electrode active material layer and the first positive electrode active material layer are facing each other. A method for manufacturing an electrochemical apparatus.

13. The process of assembling the electrode assembly includes stacking the negative electrode piece and the positive electrode piece to obtain the electrode assembly, or stacking the negative electrode piece and the positive electrode piece and winding them together to obtain the electrode assembly. A method for manufacturing an electrochemical apparatus according to claim 12.

14. A lithium replenishment region is provided on the surface of the first negative electrode active material layer using at least one of lithium foil or lithium powder. A method for manufacturing an electrochemical apparatus according to claim 12.

15. An electronic device comprising an electrochemical apparatus as described in any one of claims 1 to 11.

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