An electrochemical device and an electronic device

Abstract

The application provides an electrochemical device and an electronic device. The electrochemical device comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, the positive electrode active material layer comprises conductive particles, the conductive particles comprise at least one of antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 , wherein the ratio of x1:x2 ranges from 80:20 to 95:5, and the ratio of y1:y2 ranges from 85:15 to 99:1. The antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 and the aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 have good conductivity and poor adsorption capacity, and can improve the conductivity of the conductive particles. Through the above arrangement, the conductivity of the conductive particles is improved, thereby improving the cycle performance of the electrochemical device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemistry, and in particular to an electrochemical device and an electronic device. BACKGROUND

[0002] Lithium ion batteries (electrochemical devices) have the advantages of high energy density, high open-circuit voltage, low self-discharge rate, long cycle life, good safety, etc., and are widely used in various fields such as portable energy storage, electronic devices, electric vehicles, etc. With the wide application of lithium ion batteries in the above fields, the market has increasingly high requirements for the electrochemical performance of lithium ion batteries.

[0003] In the prior art, conductive carbon is usually used to improve the conductivity of the positive electrode sheet, but during the charging and discharging process of the lithium ion battery, due to the strong adsorption of the conductive carbon, the byproduct is enriched on the surface of the conductive carbon, which causes the diameter of the conductive carbon to increase, affecting the conductivity of the conductive carbon, and thus affecting the cycle performance of the lithium ion battery. SUMMARY

[0004] The purpose of the present application is to provide an electrochemical device and an electronic device to improve the cycle performance of the electrochemical device. The specific technical solutions are as follows:

[0005] The first aspect of the present application provides an electrochemical device, which comprises a positive electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, the positive electrode active material layer comprising conductive particles, the conductive particles comprising at least one of doped antimony tin oxide (SnO) x1 (Sb2O3) x2 or doped aluminum zinc oxide (ZnO) y1 (Al2O3) y2 , wherein the ratio of x1:x2 ranges from 80:20 to 95:5, and the ratio of y1:y2 ranges from 85:15 to 99:1. The doped antimony tin oxide (SnO) x1 (Sb2O3) x2 and the doped aluminum zinc oxide (ZnO) y1 (Al2O3) y2 have good conductivity and poor adsorption capacity, which can improve the conductivity of the conductive particles. The conductive particles comprise at least one of doped antimony tin oxide (SnO) x1 (Sb2O3) x2 or doped aluminum zinc oxide (ZnO) y1 (Al2O3) y2 , and the values of x1:x2 and y1:y2 are controlled within the range of the present application, which is beneficial to improve the conductivity of the conductive particles, thereby improving the cycle performance of the electrochemical device.

[0006] In some embodiments of the present application, the antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 and / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 is located on at least part of the surface of the conductive particles, the antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 and / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 The ratio of the coverage area of the antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 and / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 to the total surface area of the conductive particles is Z, Z≥50%. By adjusting the ratio Z of the coverage area of the antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 and / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 to the total surface area of the conductive particles within the scope of the present application, the conductivity of the conductive particles can be improved, and the cycle performance of the electrochemical device can be improved.

[0007] In some embodiments of the present application, the antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 and / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 has a thickness of 0.5nm to 70nm on the surface of the conductive particles. By adjusting the thickness of the antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 and / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 on the surface of the conductive particles within the scope of the present application, the conductivity of the conductive particles can be improved, and the cycle performance of the electrochemical device can be improved.

[0008] In some embodiments of the present application, the diameter of the conductive particles is d nm, 2≤d≤150, preferably 20≤d≤70. By adjusting the diameter of the conductive particles within the scope of the present application, the conductivity of the conductive particles can be improved, and the cycle performance of the electrochemical device can be improved.

[0009] In some embodiments of the present application, the plurality of conductive particles is in the form of a string, and the length of the string composed of the conductive particles is L μm, 0.05≤L≤5. By adjusting the length of the string in which the conductive particles are in the form of a string within the scope of the present application, the long-range conductivity of the conductive particles can be increased, and at the same time, it is also beneficial for the storage of electrolyte between the conductive particles, thereby improving the ionic conductivity of the positive electrode sheet and further improving the cycle performance of the electrochemical device.

[0010] In some embodiments of the present application, the specific surface area BET of the string-shaped conductive particle is 150 m 2 / g to 1000 m 2 / g. By adjusting the specific surface area of the string-shaped conductive particle, the conductivity of the conductive particle is improved, and the cycle performance of the electrochemical device is further improved.

[0011] In some embodiments of the present application, the internal part of the conductive particle is carbon element, antimony-doped tin oxide (SnO x1 (Sb2O3) x2 or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 By the above arrangement, the conductive particle has good conductivity, and the cycle performance of the electrochemical device is improved.

[0012] In some embodiments of the present application, the positive electrode active material layer comprises a positive electrode active material, and the particle size of the positive electrode active material satisfies at least one of the following characteristics: (1) 5 μm≤Dv50≤20 μm, 25 μm≤Dv99≤50 μm; (2) 80≤Dv50 / d≤6000; (3) 5≤Dv99 / L≤1000. The particle size of the positive electrode active material satisfies at least one of the above characteristics, which is beneficial to the gradation of the conductive particle and the positive electrode active material, improves the compaction density of the positive electrode sheet, and enables the lithium ion battery to have a higher energy density.

[0013] In some embodiments of the present application, the mass percentage of the conductive particle is 0.1% to 3% based on the mass of the positive electrode active material layer. By adjusting the mass percentage of the conductive particle within the scope of the present application, the conductivity of the positive electrode sheet is improved, and the cycle performance of the electrochemical device is improved.

[0014] In some embodiments of the present application, the diameter growth rate of the conductive particle is ≤15% after the electrochemical device is cycled for 501 times at 45°C. The diameter growth rate of the conductive particle is small, the conductive particle still maintains good conductivity, and the electrochemical device has good cycle performance.

[0015] The second aspect of the present application provides an electronic device comprising the electrochemical device provided by the first aspect of the present application. The electrochemical device provided by the first aspect of the present application has good cycle performance, so that the electronic device provided by the second aspect of the present application has a longer service life.

[0016] The beneficial effects of the present application are:

[0017] The application provides an electrochemical device and an electronic device. The electrochemical device comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, and the positive electrode active material layer comprises conductive particles, the conductive particles comprise at least one of doped antimony tin oxide (SnO) x1 (Sb2O3) x2 or doped aluminum zinc oxide (ZnO) y1 (Al2O3) y2 , wherein the ratio of x1:x2 ranges from 80:20 to 95:5, and the ratio of y1:y2 ranges from 85:15 to 99:1. The doped antimony tin oxide (SnO) x1 (Sb2O3) x2 and the doped aluminum zinc oxide (ZnO) y1 (Al2O3) y2 have good conductivity and poor adsorption capacity, and can improve the conductivity of the conductive particles. The conductive particles comprise at least one of doped antimony tin oxide (SnO) x1 (Sb2O3) x2 or doped aluminum zinc oxide (ZnO) y1 (Al2O3) y2 , and the values of x1:x2 and y1:y2 are regulated within the range of the application, which is beneficial to improving the conductivity of the conductive particles, thereby improving the cycle performance of the electrochemical device.

[0018] Of course, implementing any product or method of the present application does not necessarily require achieving all the advantages described above at the same time. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described below. Obviously, the described embodiments are only some of the embodiments of the present application, not all. All other embodiments obtained by those skilled in the art based on the present application are within the scope of protection of the present application.

[0020] It should be noted that in the specific embodiments of the present application, lithium ion batteries are used as examples of electrochemical devices to explain the present application, but the electrochemical devices of the present application are not limited to lithium ion batteries.

[0021] The first aspect of the present application provides an electrochemical device, which comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, and the positive electrode active material layer comprises conductive particles, the conductive particles comprise at least one of doped antimony tin oxide (SnO) x1 (Sb2O3) x2 or doped aluminum zinc oxide (ZnO) y1 (Al2O3) y2At least one of the following, wherein the ratio of x1:x2 ranges from 80:20 to 95:5, and the ratio of y1:y2 ranges from 85:15 to 99:1. For example, antimony-doped tin oxide (SnO). x1 (Sb2O3) x2 In the ratio x1:x2, it can be 80:20, 83:17, 85:15, 87:13, 90:10, 93:7, 95:5, or a range of any two of these values; aluminum-doped zinc oxide (ZnO). y1 (Al2O3) y2 In the range y1:y2, it can be 85:15, 87:13, 90:10, 93:7, 95:5, 99:1, or any two of these values.

[0022] The researchers in this application discovered that antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 And aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 It possesses good conductivity and poor adsorption capacity, which is beneficial for improving the conductivity of conductive particles, reducing the accumulation of by-reaction products on the surface of conductive particles, decreasing the diameter growth rate of conductive particles, and promoting the uniform distribution of binders and conductive particles in the positive electrode sheet. This, in turn, improves the conductivity of the positive electrode sheet and reduces cell polarization. Conductive particles include antimony-doped tin oxide (SnO). x1 (Sb2O3) x2 Or it can be zinc oxide (ZnO) with aluminum added. y1 (Al2O3) y2 Using at least one of the following, and adjusting the values ​​of x1:x2 and y1:y2 within the scope of this application, is beneficial to improving the conductivity of conductive particles and improving the cycle performance of electrochemical devices.

[0023] In some embodiments of this application, antimony-doped tin oxide (SnO) is used. x1 (Sb2O3) x2 And / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 Antimony-doped tin oxide (SnO) is located on at least a portion of the surface of the conductive particles. x1 (Sb2O3) x2 And / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 The ratio of the coverage area to the total surface area of ​​the conductive particles is Z, where Z ≥ 50%. For example, the value of Z can be 50%, 60%, 70%, 80%, 90%, 100%, or a range of any two of these values. This can be achieved by adjusting the antimony-doped tin oxide (SnO). x1 (Sb2O3) x2and / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 The ratio Z of the coverage area of the conductive particles to the total surface area of the conductive particles in the range of the present application is conducive to improving the conductivity of the conductive particles, improving the accumulation of byproduct on the surface of the conductive particles, reducing the polarization of the battery, and improving the cycle performance of the electrochemical device.

[0024] In some embodiments of the present application, the tin oxide (SnO) x1 (Sb2O3) x2 and / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 The thickness of the conductive particle surface is 0.5 nm to 70 nm. For example, the tin oxide (SnO) x1 (Sb2O3) x2 and / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 The thickness of the conductive particle surface can be 0.5 nm, 1 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, or a range formed by any two of the above values. By adjusting the thickness of the tin oxide (SnO) x1 (Sb2O3) x2 and / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 The thickness of the conductive particle surface in the range of the present application is conducive to improving the conductivity of the conductive particles and improving the cycle performance of the electrochemical device.

[0025] In some embodiments of the present application, the diameter of the conductive particle is d nm, 2≤d≤150, preferably 20≤d≤70. For example, the diameter of the conductive particle can be 2 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 120 nm, 140 nm, 150 nm, or a range formed by any two of the above values. By adjusting the diameter of the conductive particle in the range of the present application, it is conducive to improving the conductivity of the conductive particles and improving the cycle performance of the electrochemical device.

[0026] In some embodiments of the present application, the plurality of conductive particles is in the form of a string, and the length of the string formed by the plurality of conductive particles is L μm, and 0.05≤L≤5. For example, the length of the string formed by the plurality of conductive particles can be 0.05 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or a range defined by any two of the above values. The plurality of conductive particles is in the form of a string and the length of the string is regulated within the scope of the present application, which can enable the plurality of conductive particles to exhibit long-range conductivity, improve the conductivity of the plurality of conductive particles, and facilitate the storage of electrolyte between the plurality of conductive particles and the transport of active metal ions (e.g., Li + ) to improve the ionic conductivity of the positive electrode sheet and further improve the cycle performance of the electrochemical device. In the present application, the plurality of conductive particles is in the form of a string, which means that the plurality of conductive particles is linked to form a string.

[0027] In some embodiments of the present application, the specific surface area BET of the string formed by the plurality of conductive particles is 150 m 2 / g to 1000 m 2 / g, for example, the specific surface area BET of the string formed by the plurality of conductive particles can be 150 m 2 / g, 300 m 2 / g, 350 m 2 / g, 400 m 2 / g, 450 m 2 / g, 500 m 2 / g, 550 m 2 / g, 600 m 2 / g, 800 m 2 / g, 900 m 2 / g, 1000 m 2 / g, or a range defined by any two of the above values. By regulating the specific surface area of the string formed by the plurality of conductive particles within the scope of the present application, the conductivity of the plurality of conductive particles can be improved, and the cycle performance of the electrochemical device can be further improved.

[0028] In some embodiments of the present application, the interior of the plurality of conductive particles is carbon, antimony-doped tin oxide (SnO x1 (Sb2O3) x2 , or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 . By the above arrangement, the plurality of conductive particles can have good conductivity and improve the cycle performance of the electrochemical device. The carbon includes at least one of graphene, Ketjen black, or conductive carbon black (Super P).

[0029] In some embodiments of the present application, the positive electrode active material layer comprises a positive electrode active material, and the particle size of the positive electrode active material satisfies at least one of the following characteristics: (1) 5 μm≤Dv50≤20 μm, 25 μm≤Dv99≤50 μm; (2) 80≤Dv50 / d≤6000; (3) 5≤Dv99 / L≤1000. The particle size of the positive electrode active material satisfying at least one of the above characteristics is beneficial to the gradation of the conductive particles and the positive electrode active material, improves the compaction density of the positive electrode sheet, can make the lithium ion battery have a higher energy density, and is beneficial to the conductivity of the conductive particles and improves the cycle performance of the lithium ion battery. "Dv50" refers to the particle size reaching 50% of the volume accumulation in the particle size distribution of the material on the volume basis, from the small particle size. "Dv99" refers to the particle size reaching 99% of the volume accumulation in the particle size distribution of the material on the volume basis, from the small particle size.

[0030] In some embodiments of the present application, the mass percentage of the conductive particles is 0.1% to 3% based on the mass of the positive electrode active material layer. For example, the mass percentage of the conductive particles can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, or a range between any two of the above values. By adjusting the mass percentage of the conductive particles within the range of the present application, the conductivity of the positive electrode sheet is improved, and the cycle performance of the electrochemical device is improved.

[0031] In some embodiments of the present application, the diameter growth rate of the conductive particles is ≤15% after the electrochemical device is cycled for 501 cycles at 45°C. The small diameter growth rate of the conductive particles indicates that the conductive particles still maintain good conductivity, and the electrochemical device has good cycle performance.

[0032] In some embodiments of the present application, the capacity retention rate of the electrochemical device is ≥80% after the electrochemical device is cycled for 501 cycles at 45°C. The electrochemical device has good cycle performance.

[0033] The preparation method of the conductive particles is not particularly limited in the present application, as long as the purpose of the present application can be achieved. For example, the preparation method of the conductive particles with carbon elements inside can include but is not limited to the following steps: first, pyrolysis and purification of a hydrocarbon substance at high temperature to obtain high-purity nano conductive carbon particles, and the hydrocarbon substance can include but is not limited to at least one of acetylene or methane. Commercially available conductive carbon particles can also be used.

[0034] Nanoscale conductive carbon particles are used as a carbon source and dissolved in water with metal salts, oxidants, precipitants, and surfactants to form an aqueous solution. This solution is transferred to a hydrothermal reactor, sealed, and allowed to react under specific temperature and pressure for a period of time. After filtration, washing, and calcination, conductive particles with an internal carbon element are obtained. These are then sintered at high temperature to obtain conductive particles in a string-like form. The internal structure of these conductive particles is antimony-doped tin oxide (SnO). x1 (Sb2O3) x2 Or it can be zinc oxide (ZnO) with aluminum added. y1 (Al2O3) y2 The preparation method may include, but is not limited to, the following steps: dissolving metal salts, oxidants, precipitants, surfactants, etc. in water to form an aqueous solution, transferring the aqueous solution to a hydrothermal reactor, sealing it, allowing it to react for a period of time under a certain temperature and pressure, and then filtering, washing, and calcining to obtain antimony-doped tin oxide (SnO). x1 (Sb2O3) x2 Or it can be zinc oxide (ZnO) with aluminum added. y1 (Al2O3) y2 The conductive particles are then sintered at high temperature to obtain conductive particles in the form of strings.

[0035] Synthesis of (SnO) x1 (Sb2O3) x2 Metal salts include tin salts and antimony salts. Tin salts may include, but are not limited to, at least one of tin dichloride, tin nitrate, and tin sulfate. Antimony salts may include, but are not limited to, at least one of antimony trichloride, antimony nitrate, and antimony sulfate. Synthesis of (ZnO) y1 (Al2O3) y2 The metal salts include zinc salts and aluminum salts. Zinc salts may include, but are not limited to, at least one of zinc dichloride, zinc sulfate, and zinc acetate. Aluminum salts may include, but are not limited to, at least one of aluminum trichloride, aluminum nitrate, and aluminum sulfate. The oxidizing agents mentioned above may include, but are not limited to, at least one of nitric acid and hydrogen peroxide. The precipitating agents may include, but are not limited to, at least one of ammonium hydroxide and sodium hydroxide. The surfactants mentioned above may include, but are not limited to, at least one of sodium nitrate and sodium dodecyl sulfate.

[0036] The temperature of the reaction in the autoclave, the pressure of the reaction in the autoclave, the time of the reaction in the autoclave, the calcination temperature, the calcination time, the high-temperature sintering temperature, and the high-temperature sintering time are not particularly limited as long as the object of the present application can be achieved, for example, the temperature of the reaction in the autoclave can be 100°C to 200°C, the pressure of the reaction in the autoclave can be 1 MPa to 5 MPa, the time of the reaction in the autoclave can be 3 h to 10 h, the calcination temperature can be 130°C to 250°C, the calcination time can be 22 h to 26 h, the high-temperature sintering temperature can be 700°C to 1100°C, and the high-temperature sintering time can be 1 h to 5 h.

[0037] The positive electrode tab is not particularly limited in the present application, as long as the object of the present application can be achieved. For example, the positive electrode tab includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. The positive electrode current collector is not particularly limited in the present application, as long as the object of the present application can be achieved. For example, the positive electrode current collector can include an aluminum foil or an aluminum alloy foil, etc. The positive electrode active material layer of the present application includes a positive electrode active material. The type of the positive electrode active material is not particularly limited in the present application, as long as the object of the present application can be achieved. For example, the positive electrode active material can include at least one of nickel cobalt manganese acid lithium (NCM811, NCM622, NCM523, NCM111), nickel cobalt aluminum acid lithium, iron lithium phosphate, lithium-rich manganese-based material, lithium cobaltate (LiCoO2), lithium manganate, lithium manganese iron phosphate, or lithium titanate, etc., preferably at least one of nickel cobalt manganese acid lithium (NCM811, NCM622, NCM523, NCM111), lithium cobaltate (LiCoO2), lithium manganate. The mass percentage of the positive electrode active material can be 93% to 99% based on the mass of the positive electrode active material layer, for example, the mass percentage of the positive electrode active material is 93%, 94%, 95%, 96%, 97%, 98%, 99%, or a range composed of any two of the above values. In the present application, the thickness of the positive electrode current collector and the positive electrode active material layer is not particularly limited, as long as the object of the present application can be achieved. For example, the thickness of the positive electrode current collector is 5 μm to 20 μm, preferably 6 μm to 18 μm. The thickness of the single-sided positive electrode active material layer is 30 μm to 120 μm. In the present application, the positive electrode active material layer can be disposed on one surface in the thickness direction of the positive electrode current collector, or on both surfaces in the thickness direction of the positive electrode current collector. It should be noted that the "surface" here can be the entire area of the positive electrode current collector, or a partial area of the positive electrode current collector, which is not particularly limited in the present application, as long as the object of the present application can be achieved. The positive electrode active material layer of the present application can further include a positive electrode conductive agent and a positive electrode binder, which are not particularly limited in the present application, as long as the object of the present application can be achieved. For example, the conductive agent can include at least one of graphene, carbon nanotubes, Ketjen black, graphite fibers, or conductive carbon black (Super P), and the mass percentage of the positive electrode conductive agent can be 0.1% to 3% based on the mass of the positive electrode active material layer, for example, the mass percentage of the positive electrode conductive agent is 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, or a range composed of any two of the above values.The positive electrode binder can include at least one of polyacrylic acid, polyvinylidene fluoride (PVDF), polytetrafluoroethylene-hexafluoropropylene, sodium polyacrylate, nitrile rubber, or polyacrylic acid ester, and the mass percentage of the positive electrode binder can be 0.5% to 4% based on the mass of the positive electrode active material layer, for example, the mass percentage of the positive electrode binder is 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or a range between any two of them.

[0038] The negative electrode tab is not particularly limited in the present application as long as the purpose of the present application can be achieved. For example, the negative electrode tab includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector. In the present application, the negative active material layer can be disposed on one surface in the thickness direction of the negative current collector, or can be disposed on both surfaces in the thickness direction of the negative current collector. It should be noted that the "surface" here can be the entire area of the negative current collector, or can be a partial area of the negative current collector, and the present application is not particularly limited as long as the purpose of the present application can be achieved. The negative current collector is not particularly limited in the present application as long as the purpose of the present application can be achieved. For example, the negative current collector can include, but is not limited to, a copper foil, a copper alloy foil, a nickel foil, a titanium foil, a foamed nickel, a foamed copper, or a composite current collector, etc. The negative active material layer of the present application contains a negative active material. The type of negative active material is not particularly limited in the present application as long as the purpose of the present application can be achieved. For example, the negative active material can include, but is not limited to, natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO x The negative electrode tab is not particularly limited in the present application as long as the purpose of the present application can be achieved. For example, the negative electrode tab includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector. In the present application, the negative active material layer can be disposed on one surface in the thickness direction of the negative current collector, or can be disposed on both surfaces in the thickness direction of the negative current collector. It should be noted that the "surface" here can be the entire area of the negative current collector, or can be a partial area of the negative current collector, and the present application is not particularly limited as long as the purpose of the present application can be achieved. The negative current collector is not particularly limited in the present application as long as the purpose of the present application can be achieved. For example, the negative current collector can include, but is not limited to, a copper foil, a copper alloy foil, a nickel foil, a titanium foil, a foamed nickel, a foamed copper, or a composite current collector, etc. The negative active material layer of the present application contains a negative active material. The type of negative active material is not particularly limited in the present application as long as the purpose of the present application can be achieved. For example, the negative active material can include, but is not limited to, natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO

[0039] The electrochemical device of the present application further includes an electrolyte, which can include a lithium salt and an organic solvent. The kind of the lithium salt is not particularly limited in the present application as long as the object of the present application is achieved, for example, the lithium salt can include, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(oxalato)borate (LiBOB), or lithium difluoro(oxalato)borate (LiDFOB). The content of the lithium salt in the electrolyte is not limited in the present application as long as the object of the present application is achieved. The kind of the above-mentioned organic solvent is not particularly limited in the present application as long as the object of the present application is achieved, for example, can include, but is not limited to, at least one of a carbonate compound, a carboxylic acid ester compound, an ether compound, or other organic solvents. The above-mentioned carbonate compound can include, but is not limited to, at least one of a chain carbonate compound or a cyclic carbonate compound. The above-mentioned chain carbonate compound can include, but is not limited to, at least one of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, or methyl ethyl carbonate. The above-mentioned cyclic carbonate compound can include, but is not limited to, at least one of vinyl carbonate, propylene carbonate, butylene carbonate, or vinyl ethylene carbonate. The above-mentioned carboxylic acid ester compound can include, but is not limited to, at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanolactone, valerolactone, or hexanolactone. The above-mentioned ether compound can include, but is not limited to, at least one of dimethyl ether of ethylene glycol, dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy-1-methoxyethane, 2-methyltetrahydrofuran, or tetrahydrofuran. The above-mentioned other organic solvents can include, but is not limited to, at least one of dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidinone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, or trioctyl phosphate.

[0040] The electrochemical device of the present application further includes a separator for separating the positive electrode sheet and the negative electrode sheet, preventing internal short circuit of the electrochemical device, allowing electrolyte ions to pass freely, and not affecting the electrochemical charging and discharging process. The separator of the present application is not particularly limited as long as the purpose of the present application can be achieved, for example, the material of the separator can include, but is not limited to, at least one of polyethylene (PE), polypropylene (PP), polyolefin (PO) separator mainly including polytetrafluoroethylene, polyester film (for example, polyethylene terephthalate (PET) film), cellulose film, polyimide film (PI), polyamide film (PA), spandex or aramid film, etc. The type of the separator can include, but is not limited to, at least one of a woven film, a non-woven film (non-woven fabric), a microporous film, a composite film, a calendered film, or a spunlaced film, etc. The separator of the present application can have a porous structure, a porous layer is provided on at least one surface of the separator, the porous layer includes inorganic particles and a binder, the inorganic particles can include at least one of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate. The binder can include at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, carboxymethyl cellulose na, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, or polyhexafluoropropylene. The size of the pore diameter of the porous structure is not particularly limited in the present application as long as the purpose of the present application can be achieved, for example, the size of the pore diameter can be 0.01 μm to 1 μm. In the present application, the thickness of the separator is not particularly limited as long as the purpose of the present application can be achieved, for example, the thickness can be 3 μm to 500 μm.

[0041] The electrochemical device of the present application further includes a packaging bag for containing the positive electrode sheet, the separator, the negative electrode sheet, and the electrolyte, and other components in the electrochemical device known in the art, and the present application does not limit the above-mentioned other components. The packaging bag of the present application is not particularly limited and can be a packaging bag known in the art as long as the purpose of the present application can be achieved. For example, an aluminum plastic film packaging bag can be used.

[0042] The electrochemical device of the present application is not particularly limited and can include any device in which an electrochemical reaction occurs. In an embodiment of the present application, the electrochemical device can include, but is not limited to, a lithium ion battery, a sodium ion battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery, etc.

[0043] The preparation process of the electrochemical device of the present application is well known to those skilled in the art, and the present application is not particularly limited, for example, can include but is not limited to the following steps: stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and winding, folding, etc. as needed to obtain a wound electrode assembly, placing the electrode assembly into a packaging bag, injecting an electrolyte into the packaging bag and sealing to obtain an electrochemical device; or stacking the positive electrode sheet, the separator and the negative electrode sheet in order, then fixing the four corners of the entire stack structure with adhesive tape to obtain a stack structure electrode assembly, placing the electrode assembly into a packaging bag, injecting an electrolyte into the packaging bag and sealing to obtain an electrochemical device. In addition, a current protection element, a guide plate, etc. can also be placed in the packaging bag as needed to prevent the pressure inside the electrochemical device from rising and overcharging and discharging.

[0044] The second aspect of the present application provides an electronic device comprising the electrochemical device provided by the first aspect of the present application. The electrochemical device provided by the present application has good cycle performance, so that the electronic device provided by the present application has a longer service life.

[0045] The electronic device of the present application is not particularly limited, and can be any electronic device known in the prior art. In some embodiments, the electronic device can include but is not limited to a notebook computer, a pen input computer, a mobile computer, an electronic book player, a portable telephone, a portable facsimile machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable recorder, a radio, a backup power supply, an electric motor, an automobile, a motorcycle, a power-assisted bicycle, a bicycle, a lighting appliance, a toy, a game machine, a clock, a power tool, a flashlight, a camera, a household large storage battery or a lithium ion capacitor, etc.

[0046] Embodiments

[0047] Hereinafter, embodiments and comparative examples are given to more specifically describe the embodiments of the present application. Various tests and evaluations were carried out according to the following methods. In addition, unless otherwise specified, "parts" and "%" are on a mass basis.

[0048] Test methods and apparatus:

[0049] Test of each characteristic amount of the conductive particles

[0050] (1) The lithium ion battery was disassembled to obtain a positive electrode sheet, which was soaked in dimethyl carbonate (DMC) at 25±5°C for 30 min, and then taken out and naturally dried.

[0051] (2) The positive electrode tab obtained in (1) is observed and tested for the diameter of 15 conductive particles and the length of a string of 15 conductive particles using a scanning electron microscope (instrument model ZEISS SEM), and the average values are recorded as the diameter d of the conductive particles and the length L of the string of conductive particles. The surface elements of the positive electrode tab are tested using EDS, and the obtained Sn element content is x1, the 1 / 2 of the Sb element content is x2, and the Zn element content is y1, and the 1 / 2 of the Al element content is y2.

[0052] (3) The positive electrode tab obtained in (1) is cut under plasma to obtain a cross section of the positive electrode tab, and the internal elements and antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 / aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 The coverage and thickness of the conductive particle surface are averaged and recorded as the antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 / aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 The coverage Z and thickness of the conductive particle surface are averaged and recorded as the antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 / aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 The coverage of the conductive particle surface is tested using statistical software.

[0053] Test of specific surface area of conductive particles

[0054] The specific surface area analyzer (Tristar II 3020M) is used to test the specific surface area of the conductive particles by nitrogen adsorption method. The specific test is carried out in accordance with the national standard GB / T 19587-2017 "Gas adsorption BET method for determination of specific surface area of solid materials".

[0055] Test of particle size of positive electrode active material

[0056] (1) The lithium ion battery is disassembled to obtain a positive electrode tab, which is soaked in dimethyl carbonate (DMC) at 25±5°C for 30 min, and then naturally dried.

[0057] (2) The positive electrode tab obtained in (1) is placed in concentrated sulfuric acid for corrosion, and the remaining particles are the positive electrode active material.

[0058] (3) The positive electrode active material particles obtained in (2) were washed and dispersed by stirring using deionized water, and then tested using a Malvern laser particle size analyzer to obtain the Dv50 and Dv99 of the positive electrode active material.

[0059] Test of the volume density of the positive electrode active material layer

[0060] (1) A lithium ion battery was disassembled to obtain a positive electrode sheet.

[0061] (2) The electrolyte on the surface of the positive electrode sheet was absorbed using a dust-free paper, and then the thickness of the sheet in the double-sided area or single-sided area was tested using a micrometer (one kind of area was uniformly selected, and the double-sided area referred to the area where the two sides of the positive electrode current collector were coated with the positive electrode active material layer, and the single-sided area referred to the area where one side of the positive electrode current collector was coated with the positive electrode active material layer); 15 positions were tested, and the average value was recorded as T.

[0062] (3) The positive electrode sheet obtained in (2) was soaked in dimethyl carbonate (DMC) at 25±5°C for 30 min, then taken out and naturally dried, and the sheet was cut into 5 pieces with a fixed area of S using a cutter, the weight of the sheet was measured, and the average value was recorded as W1.

[0063] (4) The sheet with an area of S obtained in (3) was soaked in deionized water until the positive electrode active material layer was separated from the current collector, the obtained current collector was dried, and then the weight of the current collector was measured and the average value was recorded as W2.

[0064] The volume density of the active material layer = (W1-W2) / (S×T), unit: g / cm 3 .

[0065] Test of the cycle performance

[0066] The lithium ion battery was placed in a 45°C environment for 60 min, and then discharged at a constant current of 0.5C to 3V, and then rested for 5 min.

[0067] {

charged at a constant current of 1.5C to 4.5V, then charged at a constant voltage of 4.5V to 0.05C, rested for 5 min, then discharged at a constant current of 0.7C to 3V, and rested for 5 min

[0068] The cycle 【】 was repeated 49 times, and the discharge capacity of the battery was recorded as C1, C2, C3…C 49 ; the 50th week was charged at a constant current of 0.5C to 4.5V, then charged at a constant voltage of 4.5V to 0.05C, rested for 5 min, then discharged at a constant current of 0.2C to 3V, and the discharge capacity of the lithium ion battery was recorded as C 50}

[0069] The process in the cycle {} is repeated 10 times, the process in the recycle 【】 is repeated 1 time, and the discharge capacity of the lithium ion battery at this time is recorded as C 501 The capacity retention rate of the lithium ion battery after 501 cycles is C 501 / C1 x 100%.

[0070] Conductive particle diameter growth rate test

[0071] The unused lithium ion battery is disassembled, the positive electrode sheet is taken out, washed with dimethyl carbonate (DMC), and then 50 conductive particles are observed and tested for diameter using a scanning electron microscope (instrument model ZEISS SEM). The average value is calculated and recorded as d0. The lithium ion battery under the same conditions is subjected to the above cycle performance test, and the lithium ion battery after 501 cycles at 45°C is disassembled, the positive electrode sheet is taken out, washed with DMC, and then 50 conductive particles are observed and tested for diameter using a scanning electron microscope. The average value is calculated and recorded as d 501 The conductive particle diameter growth rate is [(d 501 -d0) / d0] x 100%.

[0072] Example 1

[0073] <Preparation of positive electrode sheet>

[0074] The positive electrode active material lithium cobaltate (LiCoO2), the positive electrode binder polyvinylidene fluoride (PVDF), the conductive particles, and the positive electrode conductive agent carbon nanotube (CNT) are mixed in a mass ratio of 97.8:1.2:0.5:0.5, wherein the Dv50 of the positive electrode active material is 12 μm, the Dv99 of the positive electrode active material is 30 μm, the diameter d of the conductive particles is 0.03 μm, the length L of the conductive particle string is 1 μm, and the BET of the conductive particle string is 453 m 2 / g, (SnO) x1 (Sb2O3) x2 The thickness of the conductive particle surface is 6 nm, and x1:x2=90:10. Then N-methyl pyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75 wt%, and the slurry is stirred uniformly. The positive electrode slurry is uniformly coated on one surface of the positive electrode current collector aluminum foil with a thickness of 10 μm, and dried at 110°C to obtain a single-sided coated positive electrode active material positive electrode sheet with a positive electrode active material layer thickness of 60 μm. Then, the above steps are repeated on the other surface of the positive electrode sheet to obtain a double-sided coated positive electrode active material positive electrode sheet. After coating, the positive electrode sheet is cold-pressed and cut into a sheet with a size of 74 mm x 867 mm for use.

[0075] <Preparation of negative electrode sheet>

[0076] The negative active material graphite, butadiene styrene rubber, sodium carboxymethyl cellulose were mixed in a mass ratio of 97.5:1.3:1.2, then deionized water was added as a solvent to prepare a negative electrode slurry with a solid content of 70wt%, and stirred uniformly. The negative electrode slurry was uniformly coated on one surface of a copper foil with a thickness of 6μm, dried at 95℃, and after cold pressing, a negative electrode sheet with a single-side coated negative active material layer with a thickness of 120μm was obtained. The negative electrode sheet was cut into a sheet with a size of 74mm×875mm for use.

[0077] <Preparation of the separator>

[0078] A polyethylene film with a thickness of 5μm (provided by Celgard) was used.

[0079] <Preparation of the electrolyte>

[0080] In a dry argon glove box, the organic solvents ethylene carbonate (EC), methyl ethyl carbonate (EMC) and diethyl carbonate (DEC) were mixed in a mass ratio of 30:50:20, then lithium salt LiPF6 was added to the organic solvents to dissolve and mix uniformly, to obtain an electrolyte with a lithium salt concentration of 1.15mol / L.

[0081] <Preparation of the lithium ion battery>

[0082] The positive electrode sheet, the separator, and the negative electrode sheet were sequentially stacked in order, with the separator in the middle of the positive electrode sheet and the negative electrode sheet to play a separating role, and the electrode assembly was obtained by winding. The electrode assembly was placed in an aluminum plastic film packaging bag, and after removing the moisture at 80℃, the above electrolyte was injected and packaged, and after the processes of formation, degassing, shaping, etc., a lithium ion battery was obtained.

[0083] Examples 2 to 24

[0084] Except that the <Preparation of the positive electrode sheet> adjusted the parameters of the conductive particles according to Table 1, the rest was the same as Example 1.

[0085] Example 23

[0086] Except that the <Preparation of the positive electrode sheet> adjusted the parameters of the conductive particles according to Table 1, the conductive particles were (SnO) x1 (Sb2O3) x2 (ATO), the rest was the same as Example 1.

[0087] Example 24

[0088] Except that the <Preparation of the positive electrode sheet> adjusted the parameters of the conductive particles according to Table 1, the conductive particles were (ZnO) y1 (Al2O3) y2 (AZO), the rest was the same as Example 1.

[0089] Examples 25 to 28

[0090] Except that the relevant parameters in the <Preparation of positive electrode sheet> are adjusted according to Table 1, the rest is the same as Example 1.

[0091] Examples 29 to 30

[0092] Except that the mass percentage of the conductive particles in the <Preparation of positive electrode sheet> is adjusted according to Table 1, the mass percentage of the positive active material changes accordingly, the rest is the same as Example 1.

[0093] Comparative Example 1

[0094] Except that the <Preparation of positive electrode sheet> uses conductive carbon as the conductive particles, the rest is the same as Example 1.

[0095]

[0096]

[0097]

[0098]

[0099] The researchers of the present application found that the value of x1:x2 in the conductive particles containing at least one of antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 and the value of y1:y2 in the conductive particles containing at least one of aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 will affect the cycle performance of the lithium ion battery. As can be seen from Examples 1 to 6 and Comparative Example 1, the conductive particles contain at least one of antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 , and the values of x1:x2 and y1:y2 are controlled within the scope of the present application, which is conducive to improving the conductivity of the conductive particles, and can make the lithium ion battery have a lower increase rate of conductive particle diameter and a higher capacity retention rate, indicating that the lithium ion battery has good cycle performance.

[0100] The researchers of the present application found that the value of x1:x2 in the conductive particles containing at least one of antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 and / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2The ratio Z of the coverage area to the total surface area of ​​the conductive particles affects the cycle performance of lithium-ion batteries. As can be seen from Examples 1, 4, 7 to 10, the doping of antimony tin oxide (SnO) into the conductive particles can be controlled. x1 (Sb2O3) x2 And / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 The ratio Z of the coverage area to the total surface area of ​​conductive particles is within the scope of this application. This ratio is beneficial to improving the conductivity of conductive particles, which can enable lithium-ion batteries to have a lower conductive particle diameter growth rate and a higher capacity retention rate, indicating that lithium-ion batteries have good cycle performance.

[0101] The researchers in this application discovered that antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 And / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 The thickness of conductive particles on the surface affects the cycle performance of lithium-ion batteries. As can be seen from Examples 1, 4, 11 to 13, and 14 to 16, the thickness of antimony-doped tin oxide (SnO) can be controlled. x1 (Sb2O3) x2 And / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 Within the range specified in this application, the thickness of the conductive particle surface is beneficial to improving the conductivity of the conductive particles, which can enable the lithium-ion battery to have a lower conductive particle diameter growth rate and a higher capacity retention rate, indicating that the lithium-ion battery has good cycle performance.

[0102] The researchers of this application discovered that the diameter d of conductive particles affects the cycle performance of lithium-ion batteries. As can be seen from Examples 1, 17 to 19, by adjusting the diameter d of conductive particles within the range of this application, it is beneficial to improve the conductivity of conductive particles, which can make lithium-ion batteries have a lower conductive particle diameter growth rate and a higher capacity retention rate, indicating that lithium-ion batteries have good cycle performance.

[0103] The researchers of this application discovered that the length L of the string formed by conductive particles affects the cycle performance of lithium-ion batteries. As can be seen from Examples 1, 20 to 22, by controlling the length L of the string formed by conductive particles within the range of this application, it is beneficial to improve the conductivity of conductive particles, which can make lithium-ion batteries have a lower conductive particle diameter growth rate and a higher capacity retention rate, indicating that lithium-ion batteries have good cycle performance.

[0104] The present inventors found that the specific surface area BET of the string-shaped conductive particles affects the cycle performance of the lithium ion battery. As can be seen from Examples 1 to 30, by adjusting the specific surface area BET of the string-shaped conductive particles within the range of the present application, the conductivity of the conductive particles can be improved, the lithium ion battery can have a lower increase rate of the diameter of the conductive particles and a higher capacity retention rate, indicating that the lithium ion battery has good cycle performance.

[0105] The present inventors found that the internal substance of the conductive particles affects the cycle performance of the lithium ion battery. As can be seen from Examples 1, 4, 23 and 24, the internal substance of the conductive particles is one of carbon element, antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 , which is conducive to improving the conductivity of the conductive particles, and the lithium ion battery can have a lower increase rate of the diameter of the conductive particles and a higher capacity retention rate, indicating that the lithium ion battery has good cycle performance.

[0106] The present inventors found that the particle size Dv50 of the positive electrode active material affects the cycle performance of the lithium ion battery. As can be seen from Examples 1, 25 and 26, by adjusting the particle size Dv50 of the conductive particle positive electrode active material within the range of the present application, the lithium ion battery can have a lower increase rate of the diameter of the conductive particles and a higher capacity retention rate, indicating that the lithium ion battery has good cycle performance.

[0107] The present inventors found that the particle size Dv99 of the positive electrode active material affects the cycle performance of the lithium ion battery. As can be seen from Examples 1, 27 and 28, by adjusting the particle size Dv99 of the conductive particle positive electrode active material within the range of the present application, the lithium ion battery can have a lower increase rate of the diameter of the conductive particles and a higher capacity retention rate, indicating that the lithium ion battery has good cycle performance.

[0108] The present inventors found that the mass percentage content of the conductive particles in the positive electrode active material layer affects the cycle performance of the lithium ion battery. As can be seen from Examples 1, 29 and 30, by adjusting the mass percentage content of the conductive particles in the positive electrode active material layer within the range of the present application, the lithium ion battery can have a lower increase rate of the diameter of the conductive particles and a higher capacity retention rate, indicating that the lithium ion battery has good cycle performance.

[0109] The above description is only the preferred embodiment of the present application, and is not used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of protection of the present application.

Claims

1. An electrochemical device comprising a positive electrode, the positive electrode comprising a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector, the positive active material layer comprising conductive particles, the conductive particles comprising antimony-doped tin oxide (SnO). x1 (Sb2O3) x2 Or it can be zinc oxide (ZnO) with aluminum added. y1 (Al2O3) y2 At least one of them, wherein The ratio of x1:x2 ranges from 80:20 to 95:5, and the ratio of y1:y2 ranges from 85:15 to 99:1; the antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 And / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 Located on at least a portion of the surface of the conductive particles, the interior of the conductive particles is composed of carbon.

2. The electrochemical device according to claim 1, wherein, The antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 And / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 The ratio of the coverage area to the total surface area of ​​the conductive particles is Z, where Z ≥ 50%.

3. The electrochemical device according to claim 1, wherein, The antimony-doped tin oxide (SnO) x1 (Sb2O3) x2 And / or aluminum-doped zinc oxide (ZnO) y1 (Al2O3) y2 The thickness of the conductive particles on the surface is 0.5 nm to 70 nm.

4. The electrochemical device according to claim 1, wherein, The diameter of the conductive particles is d nm, where 2≤d≤150.

5. The electrochemical device according to claim 1, wherein, The diameter of the conductive particles is d nm, where 20 ≤ d ≤ 70.

6. The electrochemical device according to claim 1, wherein, The conductive particles are arranged in a string-like structure, and the length of the string-like structure is Lμm, where 0.05≤L≤5.

7. The electrochemical device according to claim 6, wherein, The specific surface area (BET) of the string-like structure composed of conductive particles is 150 m². 2 / g to 1000m 2 / g.

8. The electrochemical device according to claim 1, wherein, The positive electrode active material layer includes a positive electrode active material, and the particle size of the positive electrode active material satisfies at least one of the following characteristics: (1) 5μm≤Dv50≤20μm, 25μm≤Dv99≤50μm; (2) 80≤Dv50 / d≤6000; (3)5≤Dv99 / L≤1000.

9. The electrochemical device according to claim 1, wherein, Based on the mass of the positive electrode active material layer, the mass percentage of the conductive particles is 0.1% to 3%.

10. An electronic device comprising the electrochemical device according to any one of claims 1 to 9.

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