An electrochemical device and an electronic device

Abstract

The application provides an electrochemical device and an electronic device. The electrochemical device comprises an electrode assembly and an electrolyte. The electrolyte comprises a fluorine-containing compound. The electrode assembly comprises a positive electrode sheet, a negative electrode sheet and a separator. The separator is arranged between the positive electrode sheet and the negative electrode sheet. The electrode assembly is arranged in a stack mode of the positive electrode sheet, the separator and the negative electrode sheet. The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer. The positive electrode current collector is an aluminum foil and further comprises silicon. The positive electrode current collector comprises a first surface and a second surface. The positive electrode current collector has a single surface area. The first surface of the single surface area is provided with the positive electrode active material layer. The second surface of the single surface area is not provided with the positive electrode active material layer. The single surface area comprises a first part. The second surface of the first part is located on an outer surface of the electrode assembly. The first part is provided with a through hole extending in a direction from the second surface to the first surface. Through the above design, the risk of failure of the electrochemical device during the charge and discharge cycle can be reduced.

Description

Technical Field

[0001] This application relates to the field of electrochemical technology, and in particular to an electrochemical device and an electronic device. Background Technology

[0002] Most existing secondary batteries (such as lithium-ion batteries) have exposed positive electrode current collectors (usually aluminum foil), such as wound structures with the positive electrode current collector ending, wound structures with die-cut aluminum tabs, or stacked structures with the positive electrode ending on one side. As the voltage of lithium-ion batteries continues to increase, the oxidation capacity of the positive electrode sheet to the electrolyte during full charging also increases. To reduce the oxidation of the electrolyte by the positive electrode sheet, existing technologies often improve the protection of both the positive and negative electrode sheets under high voltage by continuously increasing the content of fluorine compounds in the electrolyte.

[0003] However, fluorinated compounds, such as fluorinated additives and fluorinated lithium salts, are prone to undergoing a defluorination reaction under the influence of Lewis acids (such as PF5) produced by electrolyte decomposition, generating HF. In this situation, after the lithium-ion battery is filled with electrolyte, the electrolyte comes into contact with the exposed positive electrode current collector. The HF in the electrolyte and the positive electrode current collector easily react to generate impurities. These impurities diffuse within the lithium-ion battery along with the electrolyte and accumulate in specific areas of the positive electrode (e.g., at the edge of the positive active material layer on one side of the positive electrode current collector), causing abnormalities in the positive electrode. This affects the lithium plating on the negative electrode, leading to lithium-ion battery failure during charge-discharge cycles. Therefore, how to reduce the risk of lithium-ion battery failure during charge-discharge cycles has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this application is to provide an electrochemical device and an electronic device to reduce the risk of failure of the electrochemical device during charge-discharge cycles.

[0005] It should be noted that while this application uses lithium-ion batteries as an example of an electrochemical device to explain the invention, the electrochemical device described herein is not limited to lithium-ion batteries. The specific technical solution is as follows:

[0006] A first aspect of the present application provides an electrochemical device, which includes an electrode assembly and an electrolyte, the electrolyte includes a fluorine-containing compound, the electrode assembly includes a positive electrode plate, a negative electrode plate and a separator, the separator is disposed between the positive electrode plate and the negative electrode plate, and the electrode assembly is formed by stacking the positive electrode plate, the separator and the negative electrode plate. The positive electrode plate includes a positive current collector and a positive active material layer, the positive current collector is an aluminum foil and further includes a silicon element; the positive current collector includes a first surface and a second surface opposite to each other, the positive current collector has a single-sided region, the first surface of the single-sided region is provided with the positive active material layer, and the second surface of the single-sided region is not provided with the positive active material layer. The single-sided region includes a first portion, the second surface of the first portion is located on the outer surface of the electrode assembly, and the first portion is provided with through holes extending in the direction from the second surface to the first surface. Through the above design, during the electrolyte injection and formation process or the charge-discharge cycle process of the electrochemical device, by-products generated by the reaction between the electrolyte and the positive current collector or the positive active material layer are directly attached to the through holes, and can react with the positive electrode plate in situ, which reduces the risk of by-products accumulating in a specific region or other regions of the positive electrode plate. In this way, the risk of abnormality occurring in the positive electrode plate is reduced, thereby reducing the risk of failure of the electrochemical device during the charge-discharge cycle process.

[0007] In one embodiment of the present application, the mass percentage content of the silicon element in the positive current collector is e%, and 0.03<e≤0.13. The fluorine-containing compound includes a fluorine-containing additive, the mass percentage content of the fluorine-containing additive in the electrolyte is f%, and 0.1≤f≤40.0. When the electrolyte includes the fluorine-containing additive and the mass percentage content of the fluorine-containing additive in the electrolyte is adjusted within the above range, by selecting the positive current collector with the silicon element content in the above range, the protection ability of the electrolyte to the negative electrode plate can be enhanced, and a uniform and dense protective film can be formed on the surface of the negative electrode plate, thereby improving the cycle performance of the electrochemical device; at the same time, the content of the fluorosilicon compound, which is a by-product generated by the reaction of HF in the electrolyte with the silicon element in the positive current collector, is reduced. In this way, the risk of abnormality occurring in the positive electrode plate is reduced, thereby reducing the risk of failure of the electrochemical device during the charge-discharge cycle process.

[0008] In one embodiment of the present application, 0.5≤fe≤3.6. Preferably, 0.5≤fe≤2.4. By adjusting the value of fe within the above range, the mass percentage content of the silicon element in the positive current collector and the mass percentage content of the fluorine-containing additive in the electrolyte are matched, which is more conducive to reducing the risk of failure of the electrochemical device during the charge-discharge cycle process.

[0009] In one embodiment of the present application, the cross-sectional area of the through hole is b mm 20.1≤b≤1.0. By controlling the cross-sectional area of ​​the through-hole within the above range, the risk of abnormality in the positive electrode is reduced, thereby reducing the risk of failure of the electrochemical device during charge-discharge cycles.

[0010] In one embodiment of this application, the number of through holes is multiple, and the number of through holes per unit area is d holes / cm, calculated based on the area of ​​the second surface of the first part. 2 2≤d≤10. Preferably, 6≤d≤10. By controlling the number of through holes per unit area of ​​the second surface of the first part within the above range, the risk of abnormality of the positive electrode is reduced, thereby reducing the risk of failure of the electrochemical device during charge-discharge cycles.

[0011] In one embodiment of this application, 0 < f / (db) ≤ 100. Preferably, 0 < f / (db) ≤ 60. By controlling the value of f / (db) within the above range, the risk of abnormality of the positive electrode is reduced, thereby further reducing the risk of failure of the electrochemical device during charge-discharge cycles.

[0012] In one embodiment of this application, the fluorinated additive includes at least one of fluoroethylene carbonate, bis(fluoromethyl)ethylene carbonate, bis(difluoromethyl)ethylene carbonate, bis(trifluoromethyl)ethylene carbonate, bis(2-fluoroethyl)ethylene carbonate, bis(2,2-difluoroethyl)ethylene carbonate, bis(2,2,2-trifluoroethyl)ethylene carbonate, 2-fluoroethylmethylethylene carbonate, 2,2-difluoroethylmethylethylene carbonate, or 2,2,2-trifluoroethylmethylethylene carbonate. Using the above-mentioned types of fluorinated additives is more effective in reducing the oxidizing power of the positive electrode sheet on the electrolyte, forming a uniform and dense protective film on the surfaces of both the positive and negative electrode sheets, thus protecting them.

[0013] In one embodiment of this application, the fluorinated compound further includes a fluorinated lithium salt, which includes at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium bis(trifluoromethane)sulfonylimide, lithium bisfluorosulfonylimide, lithium tetrafluoroborate, lithium difluorooxalate borate, lithium hexafluoroantimonyate, lithium hexafluoroarsenate, lithium perfluorobutylsulfonate, lithium bissulfonylimide, or lithium fluoride. The addition of the fluorinated lithium salt further facilitates the provision of high ionic conductivity, resulting in a faster lithium-ion transport rate.

[0014] In one embodiment of this application, the electrode assembly has a stacked structure; or, the electrode assembly has a wound structure, and the positive current collector further includes a double-sided region, with the double-sided region and the single-sided region connected sequentially along the winding direction.

[0015] In one embodiment of this application, the through-hole is formed by punching from the second surface to the first surface. This reduces the risk of burrs coming into contact with the packaging bag, preventing the packaging bag from being punctured by the burrs generated by the through-hole, thereby improving the encapsulation performance and safety performance of the electrochemical device.

[0016] In one embodiment of this application, the electrochemical device further includes a packaging bag containing electrode components and electrolyte, with a first portion connected to the packaging bag.

[0017] A second aspect of this application provides an electronic device that includes the electrochemical device provided in the first aspect of this application. Therefore, the beneficial effects of the electrochemical device provided in the first aspect of this application can be obtained.

[0018] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.

[0020] Figure 1 This is a schematic diagram of the electrode assembly structure of some embodiments of this application;

[0021] Figure 2 for Figure 1 A schematic diagram of the cross-sectional structure of the positive electrode sheet in the electrode assembly in its unfolded state along its own thickness direction;

[0022] Figure 3 for Figure 2 A schematic diagram of the structure of the positive electrode sheet as viewed along its own thickness direction;

[0023] Figure 4 for Figure 3 Enlarged view of the figure marked with dashed box 301 in the attached drawing;

[0024] Figure 5 This is a schematic diagram of the electrode assembly structure of some embodiments of this application;

[0025] Figure 6 for Figure 5 A schematic diagram of the cross-sectional structure of the positive electrode sheet in the electrode assembly in its unfolded state along its own thickness direction;

[0026] Figure 7 This is a schematic diagram of the structure of the positive electrode sheet in some embodiments of this application;

[0027] Figure 8 This is a schematic diagram of the cross-sectional structure of the positive electrode sheet of Comparative Example 1 in its unfolded state along its own thickness direction. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0029] It should be noted that, in the specific embodiments of this application, lithium-ion batteries are used as an example of electrochemical devices to explain this application, but the electrochemical devices of this application are not limited to lithium-ion batteries.

[0030] Electrochemical devices (such as lithium-ion batteries) typically have exposed positive electrode current collectors. Current technologies often use aluminum foil with a silicon content of 0.06% to 0.18% by mass, with most silicon existing as silicon dioxide or silicates. As the voltage of electrochemical devices increases, the oxidation of the electrolyte by the positive electrode at full charge also increases. To reduce this oxidation, current technologies often increase the content of fluorine compounds in the electrolyte to improve protection of both the positive and negative electrodes at high voltages.

[0031] However, fluorinated compounds, such as fluorinated additives and fluorinated lithium salts, are prone to undergoing de-fluorination reactions under the action of Lewis acids (such as PF5) produced by electrolyte decomposition, generating HF. In this case, after the electrochemical device is filled with electrolyte, the electrolyte comes into contact with the bare aluminum foil. The HF in the electrolyte may react with components in the aluminum foil, such as silicon dioxide or silicates, to generate byproduct fluorosilicone compounds. These byproduct fluorosilicone compounds diffuse inside the electrochemical device and accumulate in specific areas of the positive electrode (e.g., at the edge of the positive active material layer in the single-sided area of ​​the positive current collector), causing abnormalities in the positive electrode (e.g., significant color difference in local areas due to increased silicon content). The abnormal areas of the positive electrode cannot properly delithiate, and lithium ions escape from the edges of these abnormal areas, resulting in insufficient lithium intercalation sites on the corresponding negative electrode, leading to lithium plating and ultimately causing the electrochemical device to fail during charge-discharge cycles. To solve the problem of electrochemical device failure during charge-discharge cycles, this application provides an electrochemical device and an electronic device.

[0032] This application provides an electrochemical device comprising an electrode assembly and an electrolyte, the electrolyte comprising a fluorinated compound. The electrode assembly comprises a positive electrode, a negative electrode, and a separator, the separator being disposed between the positive and negative electrode. The electrode assembly is composed of a positive electrode, a separator, and a negative electrode stacked together. The positive electrode comprises a positive current collector and a positive active material layer. The positive current collector is an aluminum foil and also includes silicon. The positive current collector comprises a first surface and a second surface opposite to each other. The positive current collector has a single-sided region. The first surface of the single-sided region is provided with the positive active material layer, and the second surface of the single-sided region is not provided with the positive active material layer. The single-sided region includes a first portion, the second surface of which is located on the outer surface of the electrode assembly. The first portion is provided with a through-hole extending in a direction from the second surface to the first surface.

[0033] It can be understood that a single-sided region is a segment of the positive electrode current collector; therefore, the first surface of the single-sided region is the first surface of the positive electrode current collector, and the second surface of the single-sided region is the second surface of the positive electrode current collector. A first part is either a segment or the entirety of the single-sided region, which is also a segment of the positive electrode current collector; therefore, the first surface of the first part is the first surface of the positive electrode current collector, and the second surface of the first part is the second surface of the positive electrode current collector. It should be noted that, unless otherwise specified, the areas of the first and second surfaces are the same.

[0034] By placing part or all of the second surface of the first part, i.e., the single-sided area, on the outer surface of the electrode assembly, the possibility of direct contact between the negative electrode current collector (such as copper foil) and the packaging bag is reduced, thus lowering the risk of corrosion from contact between the copper foil and the aluminum foil in the packaging bag. This improves the encapsulation performance and safety of the electrochemical device. Simultaneously, the first part being a single-sided area, located at the end of the electrode assembly, saves on the amount of positive electrode active material layer used, reducing the production cost of the electrochemical device. The vias allow byproducts generated during the electrolyte reaction with the positive electrode current collector or positive electrode active material layer during electrolyte injection or charge-discharge cycles to adhere directly to the vias, reacting in situ with the positive electrode sheet. This reduces the risk of byproduct accumulation in specific or other areas of the positive electrode sheet. This reduces the risk of abnormalities in the positive electrode sheet, thereby lowering the risk of device failure during charge-discharge cycles.

[0035] Exemplary examples, in some embodiments of this application, such as Figures 1 to 6As shown, the electrode assembly 001 has a wound structure, with the winding direction indicated by W. The electrode assembly 001 includes a positive electrode 100, a negative electrode 200, and a separator 300 disposed between the positive electrode 100 and the negative electrode 200. The positive electrode 100 includes a positive current collector 10 and a positive active material layer 20 disposed on the positive current collector 10. The positive current collector 10 includes opposing first surfaces 10a and second surfaces 10b, and includes a single-sided region 30. The first surface 10a of the single-sided region 30 is provided with the positive active material layer 20, while the second surface 10b of the single-sided region 30 is not provided with the positive active material layer 20. The single-sided region 30 includes a first portion 301, and the second surface 10b of the first portion 301 is located on the outer surface of the electrode assembly 001. The first portion 301 has a through hole 50 extending in the direction from the second surface 10b to the first surface 10a. Figures 1 to 4 As shown, the positive current collector 10 also includes a double-sided region 40, a first double-sided empty foil region 61 and a second double-sided empty foil region 62. The portion of the single-sided region 30 other than the first part 301 is not located on the outer surface of the electrode assembly 001. The second surface 10b of the first part 301 is located on the outer surface of the electrode assembly 001. The first part 301 is provided with a through hole 50 extending in the direction from the second surface 10b to the first surface 10a. Figure 5 The positive current collector in the electrode assembly shown does not include the second double-sided empty foil region 62, which includes a double-sided region 40, a single-sided region 30, and a first double-sided empty foil region 61, as shown. Figure 5 and Figure 6 As shown, the first part 301 can be understood as a single-sided area 30, and the second surface 10b of the first part 301 can also be understood as the second surface 10b of the single-sided area 30. That is, the second surface 10b of the single-sided area 30 is located on the outer surface of the electrode assembly 001, and the single-sided area 30 is provided with a through hole 50 extending in the direction from the second surface 10b to the first surface 10a.

[0036] Exemplary, in some embodiments of this application, the electrode assembly has a stacked structure, consisting of a positive electrode, a negative electrode, and a separator between the positive and negative electrode layers. The two outermost layers of the electrode assembly along its thickness direction are both single-sided positive electrode sheets. Specifically, as shown... Figure 7As shown, the single-sided positive electrode includes a positive current collector 10, which includes a first surface 10a and a second surface 10b opposite to each other. The positive current collector 10 includes a single-sided region 30. The first surface 10a of the single-sided region 30 is provided with a positive active material layer 20, while the second surface 10b of the single-sided region 30 is not provided with a positive active material layer 20. The single-sided region 30 includes a first portion 301, and the second surface 10b of the first portion 301 is located on the outer surface of the electrode assembly 001. The first portion 301 is provided with a through hole 50 extending in the direction from the second surface 10b to the first surface 10a. The first portion 301 can be understood as the single-sided region 30, and the second surface 10b of the first portion 301 can also be understood as the second surface 10b of the single-sided region 30, that is, the second surface 10b of the single-sided region 30 is located on the outer surface of the electrode assembly, and the single-sided region 30 is provided with a through hole 50 extending in the direction from the second surface 10b to the first surface 10a. Typically, the positive electrode sheet not located on the outer surface of the electrode assembly is a double-sided positive electrode sheet. The double-sided positive electrode sheet includes a positive current collector, which includes a first surface and a second surface opposite to each other. Both the first surface and the second surface are provided with a positive active material layer.

[0037] This application does not impose any particular limitation on the area of ​​the second surface of the first part. It can vary depending on the size of the ratio of the first to the second surface area of ​​the positive current collector. Those skilled in the art can choose according to actual needs, as long as the purpose of this application is achieved. For example, the area of ​​the second surface of the positive current collector can be 500 mm². 2 At that time, the area of ​​the second surface of the first part is 50 mm². 2 Up to 2000mm 2 .

[0038] In one embodiment of the present application, the mass percentage of silicon element in the positive current collector is e%, where 0.03<e≤0.13. The fluorine-containing compound includes a fluorine-containing additive, and the mass percentage of the fluorine-containing additive in the electrolyte is f%, where 0.1≤f≤40.0. Preferably, 5≤f≤25. For example, the value of e is 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13 or any value within the range between any two of the aforesaid values. For example, the value of f is 0.1, 2.0, 5.0, 10.0, 15.0, 20.0, 25.0, 30.0, 35.0, 40.0 or any value within the range between any two of the aforesaid values. Controlling the mass percentage of silicon element in the positive current collector within the aforesaid range can reduce manufacturing abnormalities of the positive current collector (such as cold pressing fracture and winding fracture), enable the strength and ductility of the positive current collector to meet the requirements of its preparation process, and provide good electrical conductivity. When the electrolyte includes the fluorine-containing additive, and the mass percentage of the fluorine-containing additive in the electrolyte is controlled within the aforesaid range, by selecting the positive current collector with the aforesaid silicon element content range, the protection capability of the electrolyte for the negative electrode sheet can be enhanced, and a uniform and dense protective film can be formed on the surface of the negative electrode sheet, thereby improving the cycle performance of the electrochemical device; at the same time, the content of the by-product fluorosilicon compound generated by the reaction between HF in the electrolyte and the silicon element in the positive current collector is reduced. In this way, the risk of abnormality occurring in the positive electrode sheet is reduced, thereby lowering the risk of failure of the electrochemical device during the charge-discharge cycle process.

[0039] In one embodiment of the present application, 0.5≤fe≤3.6. Preferably, 0.5≤fe≤2.4. For example, the value of fe can be 0.5, 1.0, 1.5, 2.0, 2.4, 2.8, 3.2, 3.6 or any value within the range between any two of the aforesaid values. Controlling the value of fe within the aforesaid range enables the mass percentage of silicon element in the positive current collector and the mass percentage of the fluorine-containing additive in the electrolyte to be matched, which is more conducive to reducing the content of the by-product fluorosilicon compound generated by the reaction between HF in the electrolyte and the silicon element in the positive current collector. In this way, the risk of abnormality occurring in the positive electrode sheet is reduced, thereby lowering the risk of failure of the electrochemical device during the charge-discharge cycle process.

[0040] In one embodiment of the present application, the cross-sectional area of the through hole is b mm 20.1 ≤ b ≤ 1.0. For example, the value of b can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, or any value within any two of the above ranges. By controlling the cross-sectional area of ​​the through-hole within the above range, the through-hole is less likely to be blocked by the positive electrode slurry, the coating weight of the first part is less likely to decrease due to leakage of the positive electrode slurry into the through-hole during coating, and the strength of the first part is not affected. The size of the through-hole can expose the amount of positive electrode active material required for the in-situ reaction of by-products. In this way, during the electrolyte formation or charge-discharge cycle, by-products generated by the reaction between the electrolyte and the positive electrode current collector or positive electrode active material layer directly adhere to the through-hole and can react with the positive electrode in situ, reducing the risk of by-products accumulating in specific areas or other areas of the positive electrode. This reduces the risk of abnormalities in the positive electrode, thereby reducing the risk of failure of the electrochemical device during charge-discharge cycles.

[0041] This application does not impose any particular limitation on the shape of the through hole; those skilled in the art can choose according to the actual situation, as long as the purpose of this application can be achieved. For example, the shape of the through hole can be circular, elliptical, or polygonal, wherein the number of sides of the polygon is any one of 3 to 12. When the through hole is circular, the cross-sectional area of ​​the through hole is b mm by adjusting the radius r. 2 The change occurs; specifically, b = πr 2 .

[0042] In one embodiment of this application, the number of through holes is multiple, and the number of through holes per unit area is d holes / cm, calculated based on the area of ​​the second surface of the first part. 2 2≤d≤10. Preferably, 6≤d≤10. For example, the number of through holes per unit area on the second surface of the first part is 2, 3, 4, 5, 6, 7, 8, 9, or 10. By controlling the number of through holes per unit area on the second surface of the first part within the above range, without affecting the strength of the first part, the number of through holes provided in the first part can expose the amount of positive electrode active material required for the in-situ reaction of by-products. In this way, during the liquid injection formation or charge-discharge cycle, by-products generated by the reaction between the electrolyte and the positive electrode current collector or positive electrode active material layer are directly attached to the through holes and can react with the positive electrode in situ, reducing the risk of by-products accumulating in specific areas or other areas of the positive electrode. This reduces the risk of abnormalities in the positive electrode, thereby reducing the risk of failure of the electrochemical device during charge-discharge cycles.

[0043] For example, Figure 4The first part 301 is shown to have a through hole 50 extending along the direction from the second surface 10b to the first surface 10a, and the through hole 50 is circular in shape. It should be noted that the number of through holes 50 in the accompanying drawings of this application is only schematic illustration and is not intended to limit the number of through holes.

[0044] In this application, the "multiple" in "multiple through holes" is not subject to any specific quantity limit, as long as the number of through holes is between 2 and 10 per unit area of ​​the second surface of the first part.

[0045] This application does not specifically limit the type of aluminum foil; it can be any aluminum foil known in the art, as long as it can achieve the purpose of this application.

[0046] This application does not impose any particular restrictions on the method for controlling the mass percentage of silicon in the positive electrode current collector, as long as the purpose of this application can be achieved. For example, it can be achieved by adjusting the types of raw materials used to prepare the positive electrode current collector and the proportions of each raw material.

[0047] In one embodiment of this application, 0 < f / (db) ≤ 100. Preferably, 0 < f / (db) ≤ 60. For example, the value of f / (db) is 0.01, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, or any value between any two of the above ranges. By adjusting the value of f / (db) within the above range, the area of ​​the through-holes in the second surface of the first part is matched with the mass percentage of the fluorinated additive in the electrolyte. The proportion of the total area of ​​the through-holes in the first part within the total area of ​​the first part can expose the amount of positive electrode active material required for the in-situ reaction of by-products. In this way, during the electrolyte injection formation or charge-discharge cycle, by-products generated by the reaction between the electrolyte and the positive electrode current collector or the positive electrode active material layer directly adhere to the through-holes and can react with the positive electrode sheet in situ, reducing the risk of by-products accumulating in specific areas or other areas of the positive electrode sheet. This reduces the risk of abnormalities in the positive electrode, thereby further reducing the risk of failure of the electrochemical device during charge-discharge cycles.

[0048] In one embodiment of this application, the fluorinated additive includes at least one of fluoroethylene carbonate (FEC), bis(fluoromethyl)ethylene carbonate (DFEC), bis(difluoromethyl)ethylene carbonate, bis(trifluoromethyl)ethylene carbonate, bis(2-fluoroethyl)ethylene carbonate, bis(2,2-difluoroethyl)ethylene carbonate, bis(2,2,2-trifluoroethyl)ethylene carbonate, 2-fluoroethylmethylethylene carbonate, 2,2-difluoroethylmethylethylene carbonate, or 2,2,2-trifluoroethylmethylethylene carbonate. Using the above-mentioned types of fluorinated additives is more effective in reducing the oxidizing power of the positive electrode sheet on the electrolyte, forming a uniform and dense protective film on the surfaces of both the positive and negative electrode sheets, thus protecting them.

[0049] In one embodiment of this application, the electrolyte further includes a fluorinated lithium salt, including lithium hexafluorophosphate (LiPF6), lithium difluorophosphate (LiPF2), lithium bis(trifluoromethane)sulfonylimide (LiTFSI), lithium bis(fluorosulfonylimide) (LiTSI), lithium tetrafluoroborate (LiBF4), lithium difluorooxalate borate (LiBF2(C2O4), LiDFOB), lithium hexafluoroantimonyate (LiSbF6), lithium hexafluoroarsenate (LiAsF6), lithium perfluorobutyl sulfonate (LiC4F9SO3), and lithium bis(sulfonylimide) (LiN(C x F 2x+ 1SO2)(C y F 2y+1 SO2), where x and y are positive integers and x≤10, y≤10), or at least one of lithium fluoride (LiF). The addition of fluorinated lithium salts is more conducive to providing high ionic conductivity, resulting in faster lithium-ion transport rates. Preferably, the fluorinated lithium salt includes at least one of LiPF6, LiTFSI, or LiTSI, which is more conducive to reducing the production cost of electrochemical devices.

[0050] This application does not impose any particular limitation on the mass percentage of fluorinated lithium salt in the electrolyte, as long as the purpose of this application is achieved. For example, the mass percentage of fluorinated lithium salt in the electrolyte can be 8% to 20%.

[0051] In one embodiment of this application, the electrode assembly has a stacked structure.

[0052] In one embodiment of this application, such as Figure 1 and Figure 2 As shown, the electrode assembly has a wound structure, and the positive electrode current collector 10 also includes a double-sided region 40. Along the winding direction W, the double-sided region 40 is sequentially connected to the single-sided region 30. A positive electrode active material layer 20 is disposed on both the first surface 10a and the second surface 10b of the double-sided region 40.

[0053] In one embodiment of this application, the through-hole is formed by punching holes from the second surface to the first surface. The burrs generated during the creation of the through-hole are covered by the positive electrode active material layer disposed on the first surface, reducing the risk of burrs on the second surface of the first portion. This reduces the risk of burrs contacting the packaging bag, preventing the packaging bag from being punctured by the burrs generated by the through-hole, thereby improving the encapsulation performance and safety performance of the electrochemical device.

[0054] In one embodiment of this application, the electrochemical device further includes a packaging bag containing the electrode assembly and the electrolyte, with a first portion in contact with the packaging bag. In this application, "in contact" can mean that the second surface of the first portion is in direct contact with the inner side of the packaging bag near the electrode assembly, or that a separator, such as adhesive tape or a diaphragm, is provided between the second surface of the first portion and the inner side of the packaging bag near the electrode assembly.

[0055] This application does not impose any particular limitation on the thickness of the positive electrode current collector, as long as it achieves the purpose of this application. For example, the thickness of the positive electrode current collector can be from 8 μm to 20 μm.

[0056] This application does not impose any particular restrictions on the preparation method of the positive electrode current collector. Any preparation method known in the art can be used, as long as it can achieve the purpose of this application.

[0057] This application does not impose any particular limitation on the compaction density of the positive and negative electrode sheets after cold pressing, as long as the purpose of this application can be achieved. For example, the compaction density of the positive and negative electrode sheets after cold pressing is 3.9 g / cm³. 3 Up to 4.3 g / cm 3 .

[0058] The positive electrode active material layer of this application includes a positive electrode active material. This application does not impose any particular limitation on the type of positive electrode active material, as long as it achieves the purpose of this application. For example, the positive electrode active material may include at least one of lithium nickel cobalt manganese oxide (e.g., common NCM811, NCM622, NCM523, NCM111), lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide (LiCoO2), lithium manganese oxide, lithium manganese iron phosphate, or lithium titanate. In this application, the positive electrode active material may also include non-metallic elements, such as fluorine, phosphorus, boron, chlorine, silicon, sulfur, etc., which can further improve the stability of the positive electrode active material. Optionally, the positive electrode active material layer also includes a conductive agent and a binder. This application does not impose any particular limitation on the types of conductive agents and binders in the positive electrode active material layer, as long as they achieve the purpose of this application. This application does not impose any particular limitation on the mass ratio of the positive electrode active material, conductive agent, and binder in the positive electrode active material layer; those skilled in the art can choose according to actual needs, as long as the purpose of this application is achieved. For example, the mass ratio of positive electrode active material, conductive agent and binder in the positive electrode active material layer is (97.5~97.9):(0.9~1.7):(1.0~2.0).

[0059] This application does not impose any particular limitation on the thickness of the positive electrode active material layer, as long as it achieves the purpose of this application. For example, the thickness of the positive electrode active material layer can be from 30 μm to 120 μm.

[0060] The negative electrode sheet of this application includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector. The aforementioned "negative electrode active material layer disposed on at least one surface of the negative electrode current collector" means that the negative electrode active material layer can be disposed on one surface of the negative electrode current collector along its thickness direction, or on two surfaces of the negative electrode current collector along its thickness direction. It should be noted that the "surface" here can be the entire area of ​​the negative electrode current collector or only a part of it; this application has no particular limitation, as long as the purpose of this application is achieved. This application has no particular limitation on the negative electrode current collector, as long as the purpose of this application is achieved. For example, the negative electrode current collector can include copper foil, copper alloy foil, nickel foil, titanium foil, nickel foam, or copper foam, etc. The negative electrode active material layer includes a negative electrode active material. This application has no particular limitation on the type of negative electrode active material, as long as the purpose of this application is achieved. For example, the negative electrode active material may include at least one of natural graphite, artificial graphite, soft carbon, hard carbon, mesophase carbon microspheres, tin-based materials, silicon-based materials, lithium titanate, transition metal nitrides, or natural flake graphite. Optionally, the negative electrode active material layer may also include at least one of a conductive agent, a stabilizer, and a binder. This application does not impose any particular limitation on the types of conductive agents, stabilizers, and binders in the negative electrode active material layer, as long as the purpose of this application is achieved. This application does not impose any particular limitation on the mass ratio of the negative electrode active material, conductive agent, stabilizer, and binder in the negative electrode active material layer, as long as the purpose of this application is achieved. For example, the mass ratio of the negative electrode active material, conductive agent, stabilizer, and binder in the negative electrode active material layer may be (97–98):(0.5–1.5):(0.5–1.5):(1.0–1.9).

[0061] This application does not impose any particular limitations on the thickness of the negative electrode current collector and the negative electrode active material layer, as long as the purpose of this application can be achieved. For example, the thickness of the negative electrode current collector can be 5 μm to 20 μm, and the thickness of the negative electrode active material layer can be 30 μm to 120 μm.

[0062] The electrolyte of this application also includes non-aqueous solvents. This application does not have any particular limitation on non-aqueous solvents, as long as they can achieve the purpose of this application. For example, the non-aqueous solvent may include, but is not limited to, at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, or propyl propionate.

[0063] This application does not impose any particular limitation on the mass percentage of non-aqueous solvents in the electrolyte, as long as the purpose of this application can be achieved. For example, the mass percentage of non-aqueous solvents in the electrolyte can be 70% to 99%.

[0064] This application does not impose any particular restrictions on the diaphragm and packaging bag; they can be any diaphragm and packaging bag known in the art, as long as they can achieve the purpose of this application.

[0065] The electrochemical device described in this application is not particularly limited and may include any device in which an electrochemical reaction occurs. In some embodiments, the electrochemical device may include, but is not limited to, lithium metal secondary batteries, lithium-ion secondary batteries, sodium-ion secondary batteries, lithium polymer secondary batteries, or lithium-ion polymer secondary batteries.

[0066] This application does not impose any particular restrictions on the preparation method of the electrochemical device; any preparation method known in the art can be used, as long as it can achieve the purpose of this application.

[0067] A second aspect of this application provides an electronic device that includes the electrochemical device provided in the first aspect of this application. Therefore, the beneficial effects of the electrochemical device provided in the first aspect of this application can be obtained.

[0068] The electronic device described in this application is not particularly limited and can be any electronic device known in the prior art. In some embodiments, the electronic device may include, but is not limited to: laptop computers, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, lithium-ion capacitors, etc.

[0069] Example

[0070] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below.

[0071] Test methods and equipment:

[0072] Detection of different element contents:

[0073] The lithium-ion batteries of each embodiment and comparative example were fully discharged and disassembled. The positive electrode active material layer on the surface of the positive electrode current collector was washed away with N-methylpyrrolidone, and finally the positive electrode current collector was cleaned with DMC. After cleaning, the positive electrode current collector was tested by inductively coupled plasma optical emission spectrometry (ICP) to obtain the content of aluminum and silicon elements.

[0074] Detection of fluorine additive content:

[0075] Lithium-ion batteries from each example and comparative example were centrifuged to obtain 10 mL of electrolyte. The mass percentage of fluorinated additives in the electrolyte could be obtained by gas chromatography.

[0076] Detection of abnormalities in the positive electrode:

[0077] After fully discharging and disassembling the lithium-ion batteries of each embodiment and comparative example, the positive electrode was visually inspected. An abnormal appearance was observed, specifically a noticeable color difference between the localized area and its surrounding area. X-ray energy dispersive spectroscopy (EDS) was performed on the positive electrode in the abnormal area. If the silicon content in the abnormal area was >2 wt%, the positive electrode was considered abnormal. If no abnormal appearance of discolored markings was observed, the positive electrode was considered normal, and EDS testing was not performed.

[0078] An abnormal appearance of the positive electrode and a silicon content >2wt% in the abnormal area are used to characterize the failure of the electrochemical device during charge-discharge cycles.

[0079] Determining whether there are any abnormalities in the manufacturing of the positive electrode sheet:

[0080] In the <Preparation of Positive Electrode> of each embodiment or comparative example, during the cold pressing process of the positive electrode, it is determined whether the positive current collector breaks or the electrode band breaks.

[0081] Example 1

[0082] <Preparation of the positive electrode>

[0083] The positive electrode active material LiCoO2, conductive agent conductive carbon black, and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 96:2:2. N-methylpyrrolidone (NMP) was added, and the mixture was stirred evenly under vacuum to obtain a positive electrode slurry with a solid content of 70 wt%. The positive electrode slurry was then uniformly coated onto a substrate such as… Figure 6 The positive electrode current collector 10 is applied to the first surface 10a of the double-sided region 40 and the single-sided region 30, and then dried at 120°C for 1 hour. The above steps are repeated on the second surface 10b of the double-sided region 40 of the positive electrode current collector 10 to obtain the desired result. Figure 6The positive electrode sheet shown is dried at 120°C for 1 hour, and then cold-pressed, slit, and cut to obtain a positive electrode sheet with dimensions of 78mm × 875mm. The dimensions of the first surface 10a of the double-sided region 40 are 78mm × 780mm, the dimensions of the first surface 10a of the single-sided region 30 are the same as those of the first surface 10a of the first part 31, which is 78mm × 80mm, and the dimensions of the first empty foil region 61 are 78mm × 15mm. The first part 301 (which can also be understood as the single-sided region 30) is provided with a through hole 50 extending along the direction from the second surface 10b to the first surface 10a. The through hole 50 is circular in shape, and its cross-sectional area is b mm². 2 =0.13mm 2 Part 1: Number of through holes (d units / cm) per unit area (301) 2 =6 pieces / cm 2 The thickness of the positive electrode active material layer 20 is 100 μm, and the thickness of the positive electrode current collector 10 is 12 μm. The mass percentage of silicon in the positive electrode current collector 10 is m% = 0.08%.

[0084] <Preparation of Negative Electrode Sheets>

[0085] Graphite (anode active material), styrene-butadiene rubber (binder), and sodium carboxymethyl cellulose (thickener) were mixed in a mass ratio of 97.4:1.4:1.2. Deionized water was added, and the mixture was stirred evenly under vacuum to obtain a cathode slurry with a solid content of 75 wt%. The cathode slurry was uniformly coated onto one surface of a 12 μm thick copper foil current collector, and then dried at 120 °C for 1 hour to obtain a cathode with a single-sided coating of 130 μm thick and a cathode active material layer. The above steps were repeated on the other surface of the cathode current collector to obtain a cathode sheet with a double-sided coating of cathode active material. After drying at 120 °C for 1 hour, the cathode sheet was cold-pressed, slit, and cut to size to obtain a cathode sheet with dimensions of 74 mm × 867 mm.

[0086] <Preparation of Electrolyte>

[0087] In an argon-atmospheric glove box with a water content of <10 ppm, EC, PC, and DEC were mixed in a mass ratio of 1:1:1 to obtain an organic solvent. Then, a fluorinated lithium salt, LiPF6, was added to the organic solvent to obtain a basic electrolyte. A fluorinated additive, FEC, was added to the basic electrolyte to obtain the final electrolyte. The mass percentage of the fluorinated lithium salt, LiPF6, in the electrolyte was 13.8%, and the mass percentage of the fluorinated additive, FEC, was f% = 20%.

[0088] <Preparation of the diaphragm>

[0089] A porous polyethylene film with a thickness of 7μm is used.

[0090] <Preparation of Lithium-ion Batteries>

[0091] The positive electrode, separator, and negative electrode prepared above are stacked in sequence, with the separator positioned between the positive and negative electrode to provide separation. The electrodes are then wound to obtain the desired shape. Figure 5 The electrode assembly with the spiral wound structure shown is then placed in an aluminum-plastic film packaging bag, dried, and injected with electrolyte. After vacuum sealing, settling, formation, degassing, and edge trimming, a lithium-ion battery is obtained.

[0092] Examples 2 to 24

[0093] Except for adjusting the relevant preparation parameters according to Table 1, everything else is the same as in Example 1.

[0094] Comparative Example 1

[0095] Besides the positive electrode sheet preparation, the positive current collector, such as... Figure 8 As shown in Figure 8, the positive current collector is in the first part 301, i.e., the single-sided region 30, which does not have through holes. The resulting positive electrode sheet is as follows. Figure 8 Except for the above, the rest is the same as in Example 1.

[0096] The relevant preparation parameters and performance tests for each embodiment and comparative example are shown in Table 1.

[0097]

[0098]

[0099] As can be seen from Examples 1 to 25 and Comparative Example 1, when a positive electrode sheet with through holes extending from the second surface to the first surface in the first part of Examples 1 to 24 is applied to a lithium-ion battery, the risk of abnormal appearance of the positive electrode sheet is reduced after charge-discharge cycles, and the Si content in the abnormal area of ​​the positive electrode sheet is less than 2 wt%, indicating that the risk of failure of the lithium-ion battery during charge-discharge cycles is reduced, and there are no abnormalities in the manufacturing of the positive electrode sheet. However, in Comparative Example 1, when a positive electrode sheet without through holes in the first part is applied to a lithium-ion battery, the risk of abnormal appearance of the positive electrode sheet is not reduced, and the Si content in the abnormal area of ​​the positive electrode sheet is greater than 2 wt%, indicating that the risk of failure of the lithium-ion battery during charge-discharge cycles is not reduced.

[0100] The cross-sectional area of ​​the through-hole typically affects the probability of lithium-ion battery failure during charge-discharge cycles. As can be seen from Examples 1 to 5, when the cross-sectional area of ​​the through-hole in the positive electrode sheet is selected within the scope of this application, the risk of abnormal appearance of the positive electrode sheet is reduced after charge-discharge cycles, and the Si content in the abnormal area of ​​the positive electrode sheet is less than 2wt%. This indicates that the risk of lithium-ion battery failure during charge-discharge cycles is reduced, and there are no abnormalities in the fabrication of the positive electrode sheet.

[0101] The number of vias per unit area on the second surface of the first part typically affects the probability of lithium-ion battery failure during charge-discharge cycles. As can be seen from Examples 3, 6 to 9, by selecting a number of vias per unit area on the second surface of the first part of the positive electrode sheet within the scope of this application, the risk of abnormal appearance of the positive electrode sheet is reduced after charge-discharge cycles, and the Si content in the abnormal areas of the positive electrode sheet is less than 2 wt%. This indicates that the risk of lithium-ion battery failure during charge-discharge cycles is reduced, and there are no abnormalities in the fabrication of the positive electrode sheet.

[0102] The mass percentage (e%) of silicon in the positive electrode current collector and the mass percentage (f%) of fluorine-containing additives in the electrolyte typically affect the probability of lithium-ion battery failure during charge-discharge cycles. As can be seen from Examples 3, 10 to 17, lithium-ion batteries using silicon content (e%) in the positive electrode current collector and fluorine-containing additive content (f%) in the electrolyte within the scope of this application exhibit reduced risk of abnormal appearance of the positive electrode after charge-discharge cycles, and the Si content in abnormal areas of the positive electrode is less than 2 wt%. This indicates that the risk of lithium-ion battery failure during charge-discharge cycles is reduced, and the positive electrode fabrication is free of abnormalities.

[0103] Furthermore, the value of fe also typically affects the probability of lithium-ion battery failure during charge-discharge cycles. As can be seen from Examples 3, 10 to 17, when lithium-ion batteries with fe values ​​within the scope of this application are selected, the risk of abnormal appearance of the positive electrode is reduced after charge-discharge cycles, and the Si content in the abnormal area of ​​the positive electrode is less than 2 wt%. This indicates that the risk of lithium-ion battery failure during charge-discharge cycles is reduced, and there are no abnormalities in the fabrication of the positive electrode.

[0104] The value of f / (db) also typically affects the probability of lithium-ion battery failure during charge-discharge cycles. As can be seen from Examples 18 to 22, lithium-ion batteries using f / (db) values ​​within the scope of this application exhibit a reduced risk of abnormal appearance in the positive electrode after charge-discharge cycles, and the Si content in abnormal areas of the positive electrode is less than 2wt%. This indicates that the risk of lithium-ion battery failure during charge-discharge cycles is reduced, and there are no abnormalities in the fabrication of the positive electrode.

[0105] The type of fluorinated additives also typically affects the probability of lithium-ion battery failure during charge-discharge cycles. As can be seen from Examples 3 and 23, when fluorinated additives are selected for lithium-ion batteries within the scope of this application, the risk of abnormal appearance of the positive electrode is reduced after charge-discharge cycles, and the Si content in abnormal areas of the positive electrode is less than 2 wt%. This indicates that the risk of lithium-ion battery failure during charge-discharge cycles is reduced, and there are no abnormalities in the positive electrode fabrication.

[0106] The type of fluorinated lithium salt also typically affects the probability of lithium-ion battery failure during charge-discharge cycles. As can be seen from Examples 3 and 24, when the type of fluorinated lithium salt used is within the scope of this application, the risk of abnormal appearance of the positive electrode is reduced after charge-discharge cycles, and the Si content in the abnormal area of ​​the positive electrode is less than 2 wt%. This indicates that the risk of lithium-ion battery failure during charge-discharge cycles is reduced, and there are no abnormalities in the fabrication of the positive electrode.

[0107] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity from another, and do not necessarily require or imply any such actual relationship or order between these entities. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0108] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0109] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. An electrochemical device, comprising an electrode assembly and an electrolyte, the electrolyte comprising a fluorine-containing compound, the electrode assembly comprising a positive electrode plate, a negative electrode plate and a separator, the separator being disposed between the positive electrode plate and the negative electrode plate, the electrode assembly being formed by laminating the positive electrode plate, the separator and the negative electrode plate; The positive electrode plate comprises a positive current collector and a positive active material layer, the positive current collector is an aluminum foil and further comprises a silicon element; the positive current collector comprises a first surface and a second surface opposite to each other, the positive current collector has a single-sided region, the first surface of the single-sided region is provided with the positive active material layer, the second surface of the single-sided region is not provided with the positive active material layer, the single-sided region comprises a first part, the second surface of the first part is located on the outer surface of the electrode assembly, and the first part is provided with through holes extending in the direction from the second surface to the first surface.

2. The electrochemical device according to claim 1, wherein, The mass percentage content of the silicon element in the positive current collector is e%, and 0.03<e≤0.13; the fluorine-containing compound comprises a fluorine-containing additive, the mass percentage content of the fluorine-containing additive in the electrolyte is f%, and 0.1≤f≤40.

0.

3. The electrochemical device according to claim 2, wherein, 0.5≤fe≤3.

6.

4. The electrochemical device according to claim 3, wherein, 0.5≤fe≤2.

4.

5. The electrochemical device according to claim 2, wherein, The cross-sectional area of ​​the through hole is b mm. 2 , 0.1≤b≤1.

0.

6. The electrochemical device according to claim 5, wherein, 0.5≤b≤1.0。 7. The electrochemical device according to claim 5, wherein, The number of through holes is multiple, and the number of through holes per unit area is d_holes / cm, calculated based on the area of ​​the second surface of the first part. 2 , 2≤d≤10.

8. The electrochemical device according to claim 7, wherein, 6≤d≤10。 9. The electrochemical device according to claim 7, wherein, 0<f / (db)≤100.

10. The electrochemical device according to claim 9, wherein, 0<f / (db)≤60.

11. The electrochemical device according to claim 2, wherein, The fluorine-containing additive comprises at least one of fluoroethylene carbonate, bis(fluoromethyl) ethylene carbonate, bis(difluoromethyl) ethylene carbonate, bis(trifluoromethyl) ethylene carbonate, bis(2-fluoroethyl) ethylene carbonate, bis(2,2-difluoroethyl) ethylene carbonate, bis(2,2,2-trifluoroethyl) ethylene carbonate, 2-fluoroethyl methyl ethylene carbonate, 2,2-difluoroethyl methyl ethylene carbonate or 2,2,2-trifluoroethyl methyl ethylene carbonate.

12. The electrochemical device according to claim 1, wherein, The fluorine-containing compound comprises a fluorine-containing lithium salt, and the fluorine-containing lithium salt comprises at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium bis(trifluoromethane)sulfonimide, lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium difluorooxalate borate, lithium hexafluoroantimonate, lithium hexafluoroarsenate, lithium perfluorobutyl sulfonate, lithium bissulfonimide or lithium fluoride.

13. The electrochemical device according to claim 1, wherein, The electrode assembly has a stacked structure; or, The electrode assembly has a wound structure, the positive current collector further comprises a double-sided region, and along the winding direction, the double-sided region and the single-sided region are connected in sequence.

14. The electrochemical device according to claim 1, wherein, The through holes are formed by punching in the direction from the second surface to the first surface.

15. The electrochemical device according to claim 1, wherein, The electrochemical device further comprises a packaging bag for accommodating the electrode assembly and the electrolyte, and the first part is in contact with the packaging bag.

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

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