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

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 the priority of a Chinese patent application with an application number of 202210763436.0 and an invention title of "Electrochemical device, its manufacturing method, and electronic device", which was filed with the Chinese Patent Office on July 1, 2022, and the entire content thereof is incorporated herein by reference.

Technical field

[0002] The present invention relates to the field of electrochemical technology, and particularly to an electrochemical device, its manufacturing method, and an electronic device.

Background technology

[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] In order to further improve the energy density of lithium - ion batteries, it can be achieved by replenishing lithium on the surface of the negative electrode sheet. However, lithium precipitation is likely to occur on the negative electrode sheet after the above - mentioned lithium replenishment, especially on the edge, which affects the safety of lithium - ion batteries.

Summary of the invention

Problems to be solved by the invention

[0005] The purpose of the present invention is to provide an electrochemical device, its manufacturing method, and an electronic device to reduce the risk of lithium precipitation on the negative electrode sheet and improve the safety and reliability of the electrochemical device. The specific technical means are as follows.

Means for solving the problems

[0006] A first aspect of the present invention provides an electrochemical device, the electrochemical device comprising an electrode assembly, the electrode assembly including a positive electrode sheet and a negative electrode sheet, the positive electrode sheet including 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 sheet including 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 including a lithium replenishment region and a lithium non-replenishment region, the lithium non-replenishment region being a region in the region of the first negative electrode active material layer where the area does not overlap with the lithium replenishment region, when the dimension in the width direction of the first negative electrode active material layer is B1 mm, the dimension in the width direction of the first positive electrode active material layer is B2 mm, and the distance between one edge extending along the longitudinal direction in the first negative electrode active material layer and the edge of the lithium replenishment region adjacent thereto and extending along the longitudinal direction is B4 mm, 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 provides a lithium non-replenishment region in the first negative electrode active material layer in the edge region of the negative electrode sheet, thereby reducing the risk of lithium precipitation on the negative electrode sheet. In the cycle process of the electrochemical device, the lithium non-replenishment region can occlude more lithium ions from the positive electrode than the lithium replenishment region, increasing the local capacitance ratio in the edge region of the negative electrode sheet and enabling it to accommodate more lithium ions from the edge of the opposing positive electrode sheet. Thereby, the risk of lithium precipitation at the edge in the width direction of the negative electrode sheet is reduced, improving the safety and reliability of the electrochemical device and balancing the energy density of the electrochemical device.

[0008] In one embodiment of the present invention, when the dimension in the longitudinal direction of the first negative electrode active material layer is A1 mm, the dimension in the longitudinal direction 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 edge of the lithium replenishment region adjacent thereto and extending along the width direction is A4 mm, 0.15 ≦ A4 ≦ 1 / 2×(A1 - A2)+1 is satisfied. By adjusting A4 within the above range, the risk of lithium precipitation at the edge in the longitudinal direction of the negative electrode sheet can be reduced, and the safety and reliability of the electrochemical device can be improved.

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

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

[0011] In one embodiment of the present invention, when viewed from the thickness direction of the negative electrode sheet, the lithium replenishment region has a stripe portion, and along the arrangement direction of the plurality of stripe portions, the dimension of the stripe portion is 0.1 mm to 2 mm, and / or in the thickness direction of the negative electrode sheet, 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 Coulomb 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.

[0012] In one embodiment of the present invention, the material of the lithium replenishment region contains at least one of lithium carbonate, lithium oxide, lithium nitride, or lithium fluoride. In the process of lithium replenishment of the negative electrode sheet, since the activity of lithium metal is high, it reacts with air and reacts in the formation process of the electrochemical device, 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 contains at least one of lithium carbonate, lithium oxide, lithium nitride, or lithium fluoride. The negative electrode sheet having the above characteristics can improve the initial Coulombic efficiency of the negative electrode sheet, which is advantageous for improving the energy density of the electrochemical device. Furthermore, it can improve the resistance on the surface of the negative electrode sheet, which is also advantageous for reducing the risk of short circuit and the short-circuit current. Also, 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 breakdown.

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

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

[0015] In one embodiment of the present invention, 0.15 ≦ A4 ≦ 5 is satisfied, and 0.15 ≦ B4 ≦ 1.75 is satisfied. When A4 and B4 are set within this range, it is possible to provide an appropriate margin that is large in the longitudinal direction and an appropriate margin that is small in the width direction, which is advantageous for improving the manufacturing efficiency and meeting the manufacturing requirements, further reducing the risk of lithium precipitation in the negative electrode sheet, and reducing the influence on the capacity of the electrochemical device.

[0016] In one embodiment of the present invention, when the electrode assembly has a laminated structure, the width direction is the extending direction of the short side of the electrode sheet, the longitudinal direction is the extending direction of the long side of the electrode sheet, and the electrode sheet includes a positive electrode sheet and a negative electrode sheet. The laminated structure is advantageous for the space utilization of the electrode assembly and improves the design capacity of the electrochemical device.

[0017] In one embodiment of the present invention, 0.15 ≤ A4 ≤ 1.75 and 0.15 ≤ B4 ≤ 1.6 are satisfied. When A4 and B4 are set within this range, appropriate margins can be provided in the longitudinal direction and the width direction, thereby reducing the risk of lithium precipitation on the negative electrode sheet and reducing the impact on the capacity of the electrochemical device.

[0018] The second aspect of the present invention provides a method for manufacturing the electrochemical device provided in the first aspect of the present invention, providing a first negative electrode active material layer on the surface of the negative electrode current collector, and providing a lithium replenishment region and a lithium non-replenishment region in the first negative electrode active material layer to obtain a negative electrode sheet, providing a first positive electrode active material layer on the surface of the positive electrode current collector to obtain a positive electrode sheet, assembling the negative electrode sheet and the positive electrode sheet to obtain an electrode assembly, and packaging the electrode assembly to obtain an electrochemical device, wherein the first negative electrode active material layer and the first positive electrode active material layer face each other.

[0019] The electrochemical device manufactured by the method provided in the second aspect of the present invention can reduce the risk of lithium precipitation on the negative electrode sheet and improve the safety and reliability of the lithium ion battery.

[0020] In one embodiment of the present invention, the process of assembling the electrode assembly includes laminating the negative electrode sheet and the positive electrode sheet to obtain an electrode assembly, or laminating and winding the negative electrode sheet and the positive electrode sheet 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 by using at least one of a lithium foil and lithium powder on the surface of the first negative electrode active material layer. By providing the lithium replenishment region by the above method, the initial Coulombic efficiency of the negative electrode sheet can be improved, which is advantageous for improving the energy density of the electrochemical device.

[0022] A third aspect of the present invention provides an electronic device, and the electronic device includes 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 non-replenishment region in the first negative electrode active material layer in the edge region of the negative electrode sheet, the risk of lithium precipitation on the negative electrode sheet is reduced. The lithium non-replenishment region can occlude more lithium ions from the positive electrode than the lithium replenishment region. In the cycle process of the electrochemical device, the local capacitance ratio in the edge region of the negative electrode sheet increases, and more lithium ions from the edge of the opposing positive electrode sheet can be accommodated, thereby reducing the risk of lithium precipitation at the edge in the width direction of the negative electrode sheet and improving the safety and reliability of the electrochemical device. Of course, implementing any product or method of the present invention does not necessarily require all of the above advantages to be realized simultaneously.

Brief Description of the Drawings

[0024] Hereinafter, in order to more clearly explain the technical means of the present invention, the drawings necessary for the embodiments will be briefly described. It is obvious that the drawings described below are only a part of the embodiments of the present invention.

[0025]

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

[0026] Hereinafter, in order to make the object, technical means, and advantages of the present invention clearer, the present invention will be described in more detail with reference to the drawings and examples. It is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the present invention are included in the protection scope of the present invention.

[0027] In the detailed embodiments of the present invention, the present invention is described by taking a lithium-ion battery as an electrochemical device, but the electrochemical device of the present invention is not limited to a lithium-ion battery.

[0028] In order to reduce the risk of lithium precipitation during the use process, an electrochemical device is usually required to be designed such that the area of the negative electrode sheet is larger than that of the positive electrode sheet. The portion of the negative electrode sheet that exceeds the positive electrode sheet is called the portion beyond the negative electrode edge. Since the portion beyond the negative electrode edge cannot withstand pressure during the formation and capacity stages of the electrochemical device, the adhesion between the separator and the negative electrode sheet in this region becomes weak, and the gap at the interface between the separator and the negative electrode sheet becomes large. During the cycling process of the electrochemical device, as the electrolyte is consumed, the electrolyte bridge at the negative electrode edge is easily broken, leading to the problem of lithium precipitation at the negative electrode edge.

[0029] Moreover, since an expansion phenomenon occurs during the cycling process of the electrochemical device, the electrode sheets expand in the width direction and the longitudinal direction, continuously pressing the electrode assembly against the case, causing the problem of deformation of the electrochemical device. Therefore, it is necessary to design and ensure a certain gap between the electrode assembly and the case. However, since there is a large amount of electrolyte at the edge of the electrode assembly after liquid injection, the content of the film-forming additive in the electrolyte at the edge increases, and the film-forming impedance at the edge of the electrode sheet becomes large during the formation and capacity stages. As a result, lithium precipitation is likely to occur at the edge of the negative electrode sheet during the cycling process.

[0030] To increase the capacity of the electrochemical device, a method of replenishing lithium to the negative electrode sheet is usually used to improve the initial Coulombic efficiency of the negative electrode sheet.

[0031] In view of the above, a first aspect of the present invention provides an electrochemical device. As shown in FIGS. 1, 2, and 3, the electrochemical device includes an electrode assembly 10. The electrode assembly 10 includes a positive electrode sheet 11 and a negative electrode sheet 12. The schematic configuration of the positive electrode sheet 11 viewed along the thickness direction is shown in FIG. 4, and the A-A cross section shown in FIG. 3 along the thickness direction of the negative electrode sheet 12 itself is shown in FIG. 5. The positive electrode sheet 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 sheet 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 replenishment region 122 and a lithium non-replenishment region 123. The lithium non-replenishment region 123 is a region where the area does not overlap with the lithium replenishment region 122 in the region of the first negative electrode active material layer 121. Referring to FIG. 3, when the dimension of the first negative electrode active material layer 121 in the width direction (y direction) is B1 mm, the dimension of the first positive electrode active material layer 111 in the width direction (y direction) is B2 mm, and the distance between one edge 1211 extending along the longitudinal direction (x direction) in the first negative electrode active material layer 121 and the edge 1221 of the lithium replenishment region adjacent thereto and extending along the longitudinal direction (x direction) is B4 mm, 0.15 ≦ B4 ≦ 1 / 2×(B1 - B2)+1 is satisfied.

[0032] The present invention realizes uniform lithium replenishment in the normal region without performing lithium replenishment at the edge of the negative electrode sheet 12 by adjusting the amount of lithium replenishment in different regions on the surface of the negative electrode sheet 12. Since lithium replenishment is not performed at the edge of the negative electrode sheet 12, the local capacity ratio at this position is large, and more lithium ions from the positive electrode sheet 11 can be accommodated. During the formation and capacity stages of the electrochemical device, lithium ions from the opposing positive electrode sheet 11 for forming a solid electrolyte film, silicate, etc. at the edge of the negative electrode sheet 12 are received, and these lithium ions become inactive lithium and cannot return to the positive electrode sheet 11. Therefore, the reversible lithium ions at the edge of the positive electrode sheet 11 are reduced. As a result, even if the electrolyte bridge is broken at the edge of the negative electrode sheet 12 or the film formation impedance at the edge of the negative electrode sheet 12 increases, the capacity ratio at this position is large and the active lithium at the edge of the opposing positive electrode sheet 11 is small. Therefore, lithium ions can be received from the edge of the opposing positive electrode sheet 11 at the edge of the negative electrode sheet 12, and the electrochemical device can reduce the risk of lithium precipitation occurring at the edge of the negative electrode sheet 12 during the cycle process.

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

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

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

[0036] In one embodiment of the present invention, the electrode assembly 10 has a wound structure, and 0.15 ≤ A4 ≤ 5 is satisfied, and 0.15 ≤ B4 ≤ 1.75 is satisfied. By adjusting the dimension of the lithium non-replenishment region 123 so as to satisfy the above relationship, the risk of lithium precipitation on the negative electrode sheet 12 can be reduced, the safety and reliability of the electrochemical device can be improved, and the influence on the capacity of the electrochemical device due to the dimension of the lithium non-replenishment region 123 being too large can be reduced.

[0037] In one embodiment of the present invention, the electrode assembly 10 has a laminated structure, and 0.15 ≤ A4 ≤ 1.75 is satisfied, and 0.15 ≤ B4 ≤ 1.6 is satisfied. By adjusting the dimension of the lithium non-replenishment region 123 so as to satisfy the above relationship, the influence on the capacity of the electrochemical device due to the dimension of the lithium non-replenishment region 123 being too large can be further reduced.

[0038] In one embodiment of the present invention, a schematic configuration diagram viewed along the thickness direction of the positive electrode sheet 11 is shown in FIG. 6, and an A-A cross-sectional view (as shown in FIG. 3) along the thickness direction of the negative electrode sheet is shown in FIG. 7. The positive electrode sheet 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. The negative electrode sheet 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. Thus, the object of the present invention can also be achieved.

[0039] In one embodiment of the present invention, when viewed from the thickness direction (z direction) of the negative electrode sheet 12, the lithium replenishment region 122 has a stripe portion. Along the arrangement direction of the plurality of stripe portions, the dimension of the stripe portion is 0.1 mm to 2 mm, and / or in the thickness direction of the negative electrode sheet 12, 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 Coulomb efficiency of the negative electrode sheet 12 and is advantageous for improving the energy density of the electrochemical device. 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.

[0040] It should be understood that the stripe portion is a lithium strip having stripe gaps formed during the process of rolling lithium metal when replenishing lithium with a metallic lithium foil. In the process of the lithium foil being combined with the negative electrode sheet 12, since the lithium strip having the stripe gaps formed as described above can be maintained, the stripe portion can be seen from the thickness direction (z direction) of the negative electrode sheet 12. After assembling the negative electrode sheet 12 and the positive electrode sheet 11 after lithium replenishment into an electrochemical device, lithium metal is occluded in the negative electrode sheet 12, and with subsequent formation and capacity treatment, the stripe portion on the surface of the negative electrode sheet 12 remains as it is. After the electrochemical device has gone through the cycle process, in the lithium replenishment region 122 of the negative electrode sheet 12, as shown in FIG. 8, there is a stripe portion, and in the lithium non-replenishment region 123 in the edge region of the negative electrode sheet 12, as shown in FIG. 9, there is no stripe portion.

[0041] In one embodiment of the present invention, the material of the lithium replenishment region 122 contains at least one of lithium carbonate, lithium oxide, lithium nitride, or lithium fluoride. In the process of lithium replenishment of the negative electrode sheet 12, since lithium metal has high activity, it reacts with air (for example, oxygen gas and trace amounts of moisture), and reacts with the fluorine-containing substance of the electrolytic solution in the formation process of the electrochemical device. Therefore, 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 contains at least one of lithium carbonate, lithium oxide, lithium nitride, or lithium fluoride. After assembling the electrode assembly 10 and injecting the electrolytic solution, lithium metal quickly reacts 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. 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 sheet 12 having the above characteristics can improve the initial Coulombic efficiency of the negative electrode sheet 12, which is advantageous for improving the energy density of the electrochemical device. And it can improve the resistance on the surface of the negative electrode sheet 12, which is also advantageous for reducing the risk of short circuit and the short circuit current. In addition, 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 contains a negative electrode active material, and the negative electrode active material contains a silicon-based material. The silicon-based material contains at least one of silicon, silicon oxygen compound (SiO x , 0 < x ≤ 2), silicon alloy, or silicon-carbon composite. The negative electrode active material of the present invention includes graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, lithium titanate Li4Ti5O with a spinel structure 12It may further contain at least one of Li-Al alloy, metallic lithium, etc. Selecting the materials within the above range is advantageous for improving the energy density of the electrochemical device.

[0043] It should be understood that for a wound electrode assembly, after the electrode sheet is unfolded, it usually has a long side and a short side. In one embodiment of the present invention, when the electrode assembly has a wound structure, the width direction is the extending direction of the short side after the electrode sheet is unfolded, and the longitudinal direction is the extending direction of the long side after the electrode sheet is unfolded. The electrode sheet of the present invention includes a positive electrode sheet 11 and a negative electrode sheet 12.

[0044] It should be understood that for a laminated electrode assembly, the electrode sheets are usually provided by laminating one by one. In one embodiment of the present invention, when the electrode assembly has a laminated structure, the width direction is the extending direction of the short side of the electrode sheet, and the longitudinal direction is the extending direction of the long side of the electrode sheet. The above electrode sheet includes a positive electrode sheet 11 and a negative electrode sheet 12.

[0045] In one embodiment of the present invention, for a laminated electrode assembly, when the dimensions of each side of the electrode sheet are the same, the width direction is the extending direction of one side of the electrode sheet, and the longitudinal direction is the direction perpendicular to the width direction in the plane where the electrode sheet is located.

[0046] In the present invention, the electrochemical device is not particularly limited and may include any device that causes an electrochemical reaction. In one embodiment of the present invention, the electrochemical device may include, but is not limited to, a lithium-ion secondary battery (lithium-ion battery), a lithium polymer secondary battery, a lithium-ion polymer secondary battery, etc. 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, a laminated structure, etc. 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 object of the present invention can be achieved. For example, the negative electrode current collector 120 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. In the present invention, the thickness of the negative electrode current collector 120 is not particularly limited as long as the object of the present invention can be 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 may be provided on two surfaces in the thickness direction of the negative electrode current collector 120. Here, the "surface" may be the entire region of the negative electrode current collector 120 or a partial region of the negative electrode current collector 120, but is not particularly limited as long as the object of the present invention can be achieved.

[0048] In the present invention, the first negative electrode active material layer 121 is provided on the surface of the negative electrode current collector 120, or further includes a functional layer 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 object 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 the object of the present invention can be achieved. For example, it may contain at least one of a carbon-based material, a metal-based material, or a conductive polymer, but is not limited thereto. 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 fiber. The metal-based material may include metal powder and / or metal fiber, but is not limited thereto. Specifically, the metal may include at least one of copper, nickel, aluminum, and silver, but is not limited thereto. The conductive polymer may include at least one of a polyphenylene derivative, polyaniline, polythiophene, polyacetylene, and polypyrrole, but is not limited thereto.

[0051] In the present invention, the binder is not particularly limited as long as the object of the present invention can be achieved. The binder may include, for example, at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylic acid, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, or nylon, but is not limited thereto.

[0052] In the present invention, the positive electrode current collector 110 is not particularly limited as long as the object of the present invention can be achieved. For example, the positive electrode current collector 110 may include an aluminum foil, an aluminum alloy foil, a composite current collector, or the like. In the present invention, the thickness of the positive electrode current collector 110 is not particularly limited as long as the object of the present invention can be achieved. For example, the thickness of the positive electrode current collector 110 is 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 the positive electrode active material is not particularly limited as long as the object of the present invention can be achieved. For example, the positive electrode active material may contain 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 manganese iron phosphate. In the present invention, the positive electrode active material may contain a non-metallic element, and the non-metallic element contains at least one of, for example, 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 object 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 may be provided on two surfaces in the thickness direction of the positive electrode current collector 110. Here, the "surface" may be the entire region of the positive electrode current collector 110 or a partial region of the positive electrode current collector 110, but is not particularly limited as long as the object of the present invention can be achieved.

[0056] In the present invention, the separator and the electrolytic solution are not particularly limited as long as the object of the present invention can be achieved, and those skilled in the art may select according to the actual situation.

[0057] The second aspect of the present invention provides a method for manufacturing the electrochemical device provided in the first aspect of the present invention. By providing a first negative electrode active material layer 121 on the surface of the negative electrode current collector 120 and providing a lithium replenishment region 122 and a lithium non-replenishment region 123 in the first negative electrode active material layer 121, a negative electrode sheet 12 is obtained. By providing a first positive electrode active material layer 111 on the surface of the positive electrode current collector 110, a positive electrode sheet 11 is obtained. The method includes assembling a negative electrode sheet 12 and a positive electrode sheet 11 to obtain an electrode assembly 10, and packaging the electrode assembly 10 to obtain an electrochemical device, wherein a first negative electrode active material layer 121 and a first positive electrode active material layer 111 face 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, it is a method of applying a negative electrode slurry on 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, it is a method of applying a positive electrode slurry on 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 replenishment region 122 and the lithium non-replenishment region 123 is not particularly limited, and known methods in this field may be used. Exemplarily, a tape may be attached to a region on the surface of the negative electrode sheet 12 where lithium replenishment is not required, and the dimensions of the tape can be adjusted according to the dimensions of the designed lithium non-replenishment region 123. Then, a lithium foil is laminated on the surface of the negative electrode sheet 12 and a rolling pressure treatment is performed. After the lithium replenishment is completed, the tape is removed to obtain a negative electrode sheet 12 in which lithium is replenished in some regions.

[0060] The electrochemical device manufactured by the method provided in the second aspect of the present invention can reduce the risk of lithium precipitation in the negative electrode sheet 12 and improve the safety and reliability of the electrochemical device.

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

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

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

[0064] In the present invention, the method of replenishing lithium is not particularly limited as long as the object of the present invention can be achieved, and those skilled in the art can select according to the actual situation. For example, a lithium foil is roll-pressed to a thickness on the micron order in a drying chamber (environmental humidity < 1.7%), and then roll-pressed in combination with the surface of the negative electrode sheet 12.

[0065] The third aspect of the present invention provides an electronic device, and the electronic device includes 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.

[0066] In the present invention, the electronic device is not particularly limited, and any electronic device used in the prior art may be used. 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 disk, 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 assist bicycle, a bicycle, a lighting fixture, a toy, a game machine, a clock, a power tool, a strobe, a camera, a large household battery, or a lithium ion capacitor, etc.

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

[0068] Measurement Methods and Devices Measurement of the form of the negative electrode sheet: After disassembling the negative electrode sheet after cycling in a drying chamber (humidity < 1.7%), washing it three times with dimethyl carbonate (DMC), drying the negative electrode sheet, observing the form of the negative electrode sheet with a scanning electron microscope (SEM), taking an SEM photograph, and measuring the width of the stripe portion.

[0069] Measurement of the form of the cross-section of the negative electrode sheet: After disassembling the negative electrode sheet, a sample is prepared by polishing it under the action of argon ions, taking a photograph of the cross-sectional form with SEM, and measuring the thickness of the stripe portion and the thickness of the lithium-containing compound layer on the surface of the negative electrode sheet.

[0070] Cycle measurement: Ambient temperature: 25 ± 5 °C Flow of cycle measurement: The lithium-ion battery is charged to the fully charged state at the maximum rated current, left standing for 5 min, discharged at a constant current to 3.0 V at 0.5 C (rate), the above charge-discharge process is repeated 500 times, further charged to the fully charged state at the maximum rated current, after cycling up to 500 times, the lithium-ion batteries are disassembled respectively, and the lithium precipitation situation is observed at the edge of the negative electrode sheet.

[0071] Judgment of the degree of lithium precipitation: After disassembling the negative electrode sheet after cycling in a drying chamber (humidity < 1.7%), taking a photograph and recording the lithium precipitation situation at the edge of the negative electrode sheet. When no lithium precipitation is found or the area of lithium precipitation < 2%, it is called no lithium precipitation. When the area of lithium precipitation is 2% - 20%, it is called mild lithium precipitation. When the area of lithium precipitation > 20%, it is called severe lithium precipitation. Here, the percentage of the area of lithium precipitation is calculated based on the area of one side of the negative electrode sheet.

[0072] Measurement of capacity: In an atmosphere of 25 °C, charge is carried out with a charging current of 0.5 C (rate) until the upper limit voltage reaches 4.2 V, and then constant current discharge is carried out with a discharge current of 0.2 C until the final voltage reaches 2.8 V. The initial discharge capacity at 0.2 C is calculated as the capacity of the lithium-ion battery.

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

[0074] Tape is attached to the area on the surface of the negative electrode sheet where lithium replenishment is not required. The dimensions of the tape may be adjusted according to the dimensions of the designed lithium non-replenished area, that is, B4 is adjusted by adjusting the dimensions of the tape. Then, a lithium foil is roll-pressed to a thickness on the micron order (2 μm) in a drying chamber (environmental humidity <1%), and then it is combined with the surface of the negative electrode sheet fabricated as above to perform a roll-pressing process. The tape on the surface of the negative electrode sheet is removed to obtain a negative electrode sheet with lithium replenished except for the edge region. The dimension A3 of the lithium replenished area is 1258 mm, B3 is 73.6 mm, the dimension A4 of the lithium non-replenished area in the edge region of the negative electrode sheet is 0 mm, and B4 is 0.15 mm. The compression density of the negative electrode sheet is 1.76 g / cm 3 is.

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

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

[0077] <Fabrication of the separator> PVDF and alumina ceramics were mixed at a mass ratio of 9:1. Deionized water as the solvent was added to prepare a slurry with a solid content of 12 wt%, and it was stirred until uniform. The slurry was uniformly coated on one surface of a polyethylene film substrate with a thickness of 15 μm and dried to obtain a separator.

[0078] <Fabrication of the lithium-ion battery> The separator was interposed between the positive electrode plate and the negative electrode plate to achieve the isolation effect. The positive electrode plate, separator, and negative electrode plate prepared as described above were stacked in order and wound to obtain an electrode assembly. The electrode assembly was placed in a packaging bag made of aluminum plastic film, left in a vacuum oven at 85 °C, dried for 12 hours to remove moisture, the electrolyte prepared as described above was injected, vacuum packaged, left standing, formed (constant current charged to 3.5 V at 0.02 C and then constant current charged to 3.9 V at 0.1 C), shaped, and capacity processed to obtain a lithium-ion battery, and the designed battery capacity was 4614 mAh.

[0079] Examples 1-2 to 1-12 It was the same as Example 1-1 except that the dimensional parameters related to the lithium-ion battery were adjusted according to Table 1.

[0080] Examples 2-1 to 2-12 It was the same as Example 1-1 except that the dimensional parameters related to the lithium-ion battery were adjusted according to Table 2.

[0081] Example 3-1 <Fabrication of Negative Electrode Plate> In the fabrication of the negative electrode plate, 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 supplement region was 94.1 mm, B3 was 42.1 mm, the dimension B4 of the lithium non-supplemented region in the edge region of the negative electrode plate was 0.2 mm, <Fabrication of Positive Electrode Plate> In the fabrication of the positive electrode plate, 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 it was the same as Example 1-1 except that <Fabrication of Lithium-Ion Battery> was different from Example 1.

[0082] <Fabrication of Lithium-Ion Battery> The separator was interposed between the positive electrode plate and the negative electrode plate to achieve the isolation effect. The positive electrode plate, separator, and negative electrode plate were stacked in order, the four corners of the entire laminated structure were fixed with tape, placed in an aluminum plastic film, upper sealed, liquid injected, and packaged to obtain a lithium-ion battery.

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

[0084] Examples 3-2 to 3-11 It was the same as Example 3-1 except that the dimensional parameters related to the lithium-ion battery were adjusted according to Table 3.

[0085] Examples 4-1 to 4-11 It was the same as Example 3-1 except that the dimensional parameters related to the lithium-ion battery were adjusted according to Table 4.

[0086] Comparative Examples 1 to 3 It was the same as Example 1-1 except that the dimensional parameters related to the lithium-ion battery were adjusted according to Table 1.

[0087] Comparative Example 4 It was the same as Example 1-1 except that the dimensional parameters related to the lithium-ion battery were adjusted according to Table 2.

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

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

[0090] The measurements of the parameters and characteristics related to 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 size of the lithium non-supplemented region provided in the edge region along the x-direction of the negative electrode sheet increases, the local capacitance ratio of the edge region along the x-direction of the negative electrode sheet also further increases, and lithium ions from the edge of the opposing positive electrode sheet can be effectively accommodated. Thereby, the problem of lithium precipitation in the edge region along the x-direction of the negative electrode sheet is improved, the risk of lithium precipitation on the negative electrode sheet is reduced, and thus the safety and reliability of the lithium-ion battery are improved.

[0093] As can be seen from Examples 1-1 to 1-12 and Comparative Example 1, as the area of the lithium non-supplemented region increases, the local capacitance ratio of the region also increases. Since 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 first charge and discharge, the available lithium ions in the positive electrode sheet decrease, and the capacity of the lithium-ion battery tends to decrease. However, if the area of the lithium non-supplemented region is too large (for example, Comparative Example 1), although the phenomenon of lithium precipitation does not occur in the edge region along the x-direction of the negative electrode sheet, the degree of decrease in the capacity of the lithium-ion battery is too large, which is disadvantageous for improving the capacity performance characteristics of the lithium-ion battery. As can be understood from this, adjusting B4 within the scope of the present invention can obtain a lithium-ion battery having excellent capacity performance characteristics.

[0094] The measurement of the parameters and characteristics regarding 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 cooperatively adjusting A4 and B4 within the scope of the present invention, as the size of the lithium non-supplemented region in the edge regions along the x-direction and y-direction of the negative electrode sheet increases, the local capacity ratio in the edge regions along the x-direction and y-direction of the negative electrode sheet also further increases, and lithium ions from the edge of the opposing positive electrode sheet can be effectively accommodated. Thereby, the problem of lithium precipitation in the edge regions along the x-direction and y-direction of the negative electrode sheet is improved, the risk of lithium precipitation in the negative electrode sheet is reduced, and thus the safety and reliability of the lithium ion battery are improved.

[0097] As can be seen from Examples 2-1 to 2-12 and Comparative Example 4, as the area of the lithium non-supplemented region increases, the capacity of the lithium ion battery tends to decrease. However, if the area of the lithium non-supplemented region is too large (for example, Comparative Example 4), although the phenomenon of lithium precipitation does not occur in the edge regions along the x-direction and y-direction of the negative electrode sheet, the degree of decrease in the capacity of the lithium ion battery is too large, which is disadvantageous for improving the capacity performance characteristics of the lithium ion battery. As can be understood from this, cooperatively adjusting A4 and B4 within the scope of the present invention can obtain a lithium ion battery having excellent capacity performance characteristics.

[0098] The measurement of parameters and characteristics regarding 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 non-supplemented region provided in the edge region along the x-direction of the negative electrode sheet increases, the local capacitance ratio of the edge region along the x-direction of the negative electrode sheet further increases, and lithium ions from the edge of the opposing positive electrode sheet can be effectively accommodated. Thereby, the problem of lithium precipitation in the edge region along the x-direction of the negative electrode sheet is improved, the risk of lithium precipitation in the negative electrode sheet is reduced, and thus the safety and reliability of the lithium-ion battery are improved.

[0101] As can be seen from Examples 3-1 to 3-11 and Comparative Example 5, as the area of the lithium non-supplemented region increases, the capacity of the lithium-ion battery tends to decrease. However, if the area of the lithium non-supplemented region is too large (for example, Comparative Example 5), the phenomenon of lithium precipitation does not occur in the edge region along the x-direction of the negative electrode sheet, but the degree of decrease in the capacity of the lithium-ion battery is too large, which is disadvantageous for improving the capacity performance characteristics of the lithium-ion battery. As can be understood from this, adjusting B4 within the scope of the present invention can obtain a lithium-ion battery having excellent capacity performance characteristics.

[0102] The measurement of parameters and characteristics regarding 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 coordinately adjusting A4 and B4 within the scope of the present invention, as the dimension of the lithium non-supplemented region provided in the edge region along the x-direction of the negative electrode sheet increases, the local capacitance ratio of the edge region along the x-direction of the negative electrode sheet also further increases, and lithium ions from the edge of the opposing positive electrode sheet can be effectively accommodated. Thereby, the problem of lithium precipitation in the edge region along the x-direction of the negative electrode sheet is improved, the risk of lithium precipitation in the negative electrode sheet is reduced, and thus the safety and reliability of the lithium-ion battery are improved.

[0105] As can be seen from Examples 4-1 to 4-11 and Comparative Example 8, as the area of the lithium non-supplemented region increases, the capacity of the lithium-ion battery tends to decrease. However, if the area of the lithium non-supplemented region is too large (for example, Comparative Example 8), the phenomenon of lithium precipitation does not occur in the edge regions along the x-direction and y-direction of the negative electrode sheet, but the degree of decrease in the capacity of the lithium-ion battery is too large, which is disadvantageous for improving the capacity performance characteristics of the lithium-ion battery. As can be understood from this, coordinately adjusting A4 and B4 within the scope of the present invention can obtain a lithium-ion battery having excellent capacity performance characteristics.

[0106] As described above, by the technical means provided by the present invention, the risk of lithium precipitation in the negative electrode sheet can be effectively reduced, the safety and reliability of the lithium-ion battery can be improved, the energy density of the lithium-ion battery can be improved, and excellent cycle characteristics can also be maintained.

[0107] The above is only a preferred embodiment of the present invention and does not limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principle scope of the present invention should all be included within the protection scope of the present invention.

Claims

1. An electrochemical device comprising an electrode assembly, the electrode assembly including a positive electrode sheet and a negative electrode sheet, the positive electrode sheet including 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 sheet including 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 including a lithium replenishment region and a lithium non-replenishment region, the lithium non-replenishment region being a region in the region of the first negative electrode active material layer that does not overlap in area with the lithium replenishment region, The width direction dimension of the first negative electrode active material layer is B １ mm, and the dimension of the first positive electrode active material layer in the width direction is B ２ mm, Let the distance between one edge extending along the longitudinal direction in the first negative electrode active material layer and the edge of the lithium replenishment region adjacent thereto and extending along the longitudinal direction be B ４ When it is mm, 0.15 ≤ B ４ ≤ 1 / 2 × (B １ − B ２ ) + 1 is satisfied An electrochemical device.

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

3. When the dimension in the width direction of the lithium replenishment region is B ３ mm, B ４ = (B １ - B ３ ) / 2 is satisfied, The electrochemical device according to claim 1.

4. When the dimension in the longitudinal direction of the lithium replenishment region is A ３ mm, A ４ = (A １ - A ３ ) / 2 is satisfied. The electrochemical device according to claim 2.

5. When viewed from the thickness direction of the negative electrode sheet, the lithium replenishment region has a stripe portion, Along the arrangement direction of the plurality of stripe portions, the dimension of the stripe portion is 0.1 mm to 2 mm, and / or In the thickness direction of the negative electrode sheet, the thickness of the stripe portion is 0.04 μm to 0.5 μm, The electrochemical device according to claim 1.

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

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

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

9. 0.15 ≤ A ４ ≤ 5, and 0.15 ≤ B ４ ≤ 1.75 The electrochemical device according to claim 8.

10. The electrode assembly has a laminated structure, the width direction is the extending direction of the short side of the electrode sheet, the longitudinal direction is the extending direction of the long side of the electrode sheet, and the electrode sheet includes a positive electrode sheet and a negative electrode sheet, The electrochemical device according to claim 2.

11. 0.15 ≤ A ４ ≤ 1.75, and 0.15 ≤ B ４ ≤ 1.6 The electrochemical device according to claim 10.

12. A method for manufacturing the electrochemical device according to any one of claims 1 to 11, By providing the first negative electrode active material layer on the surface of the negative electrode current collector and providing a lithium replenishment region and a lithium non-replenishment region in the first negative electrode active material layer, obtaining the negative electrode sheet, By providing the first positive electrode active material layer on the surface of the positive electrode current collector, the positive electrode sheet is obtained. Assembling the negative electrode sheet and the positive electrode sheet to obtain the electrode assembly, and packaging the electrode assembly to obtain the electrochemical device, wherein the first negative electrode active material layer and the first positive electrode active material layer face each other. A method for manufacturing an electrochemical device.

13. The process of assembling the electrode assembly includes obtaining the electrode assembly by laminating the negative electrode sheet and the positive electrode sheet, or obtaining the electrode assembly by laminating and winding the negative electrode sheet and the positive electrode sheet. The method for manufacturing an electrochemical device according to claim 12.

14. Providing a lithium replenishment region in the first negative electrode active material layer by using at least one of lithium foil or lithium powder on the surface of the first negative electrode active material layer. The method for manufacturing an electrochemical device according to claim 12.

15. An electronic device comprising the electrochemical device according to any one of claims 1 to 11.

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