An electrochemical device and an electronic device

Abstract

The application provides an electrochemical device and an electronic device, the electrochemical device comprising a positive electrode, the positive electrode comprising a positive electrode active material, the positive electrode active material comprising metal elements Co and Mn, wherein the mass percentage content of Mn is B% based on the total mass of the positive electrode active material; and an electrolyte, the electrolyte comprising a boron-containing lithium salt, wherein the mass percentage content of the boron-containing lithium salt is C% based on the total mass of the electrolyte; wherein 0.05≤C≤1, and 0.01≤C / 10B≤2. The electrochemical device provided by the application can simultaneously consider high-temperature stability and cycle stability under high voltage, and has excellent hot box performance.

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 have the characteristics of high specific energy, high working voltage, low self-discharge rate, small size, light weight, etc., and are widely used in various fields such as electric energy storage, portable electronic devices and electric vehicles. With the continuous expansion of the use of lithium ion batteries, the market has put forward higher requirements for lithium ion batteries, such as higher energy density and longer service life.

[0003] Increasing the working cut-off voltage of lithium ion batteries can significantly improve the energy density of the batteries, but as the voltage increases, the stability of the batteries, especially the high-temperature stability, deteriorates rapidly. The doping of the positive electrode can significantly improve the thermal stability of the positive electrode. However, with the increase of the doping elements, the positive electrode material gradually dissolves, and the thermal stability of the negative electrode is also greatly threatened. The present application mainly adjusts the positive electrode material and the electrolyte to achieve the balance of the thermal stability and the cycle stability of the positive electrode and the negative electrode. SUMMARY

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

[0005] In one embodiment, the present application provides an electrochemical device, which comprises a positive electrode, the positive electrode comprising a positive electrode active material, the positive electrode active material comprising metal elements Co and Mn, wherein the mass percentage content of Mn is B% based on the total mass of the positive electrode active material; and an electrolyte, the electrolyte comprising a boron-containing lithium salt, wherein the mass percentage content of the boron-containing lithium salt is C% based on the total mass of the electrolyte; wherein 0.05≤C≤1 and 0.01≤C / 10B≤2.

[0006] The present inventors found that the introduction of the doping element Mn has a significant effect on improving the high-temperature stability of the positive electrode material at high voltage. Without being limited by any theory, this can be due to the stability of Mn to O, which in turn improves the structural stability of the positive electrode material. However, it was also found that as the content of Mn element is further increased, the negative electrode thermal stability deteriorates, but by introducing a boron-containing lithium salt into the electrolyte, the thermal stability of the positive electrode and the negative electrode can be balanced, and it was found that when C / 10B is within the above range, the effect is most obvious. Without being limited by any theory, this can be due to the introduction of the above-mentioned boron-containing lithium salt, which inhibits the dissolution of manganese ions, and improves the thermal stability, hydrolysis stability and oxidation stability of the electrolyte, making up for the deterioration of metal element doping on the dissolution of the positive electrode material. In addition, the electrolyte containing lithium bis(oxalato)borate (LiBOB) has the following characteristics: it can form a stable and effective passivation film in propylene carbonate (PC) solution, does not corrode the aluminum foil current collector, and does not attenuate the discharge capacity under high temperature conditions, thereby achieving a balance between the thermal stability of the positive and negative electrodes.

[0007] In some embodiments, the electrochemical device satisfies at least one of the following conditions:

[0008] (a) 0.1≤C≤1;

[0009] (b) 0.05≤C / 10B≤1.

[0010] In some embodiments, the mass percentage content of Co is A% based on the total mass of the positive electrode active material, and A and B satisfy at least one of the following conditions: 0.05≤B≤0.5; 6≤A / 20B≤60. Without being limited by any theory, the content of Mn element within this range can further enhance the structural stability of the positive electrode material, thereby improving the thermal stability and high-temperature cycle stability of the battery at high voltage.

[0011] In some embodiments, the positive electrode active material comprises Li α Co 1-x-y Mn x M y O β , wherein M comprises one or more of Mg, Al, Ca, Ti, Zr, V, Cr, Fe, Ni, Cu, Zn, Ru or Sn, wherein 0.95≤α≤1.4, 0

[0012] In some embodiments, the boron-containing lithium salt comprises at least one of lithium bis(l,l-trifluoromethyl oxalate) borate, lithium bis(l-trifluoromethyl oxalate) borate, lithium difluoro(l,l-trifluoromethyl) oxalate borate, lithium difluoro oxalate borate, lithium dioxalate borate, lithium bis(l,l-trifluoromethyl malonate) borate, lithium fluoromalonate difluoroborate, or lithium bis(fluoromalonate) borate.

[0013] The boron-containing lithium salt can protect the cathode, inhibit the occurrence of related side reactions, further improve the high-temperature stability of the electrolyte and the cycle stability of the electrochemical device.

[0014] In some embodiments, the electrolyte satisfies at least one of the following:

[0015] (a) the electrolyte further comprises a carboxylic acid ester, wherein the mass percentage content of the carboxylic acid ester is X%, 10≤X≤60, based on the total mass of the electrolyte;

[0016] (b) the electrolyte further comprises vinyl carbonate and propylene carbonate, wherein the mass percentage content of the vinyl carbonate is D%, the mass percentage content of the propylene carbonate is E%, 5≤D+E≤40, and D≥E, based on the total mass of the electrolyte;

[0017] (c) the electrolyte further comprises at least one of 1,3-propane sultone, vinyl sulfate, vinylene carbonate, a bicyclic carbonate compound, a bicyclic sulfate compound, a tricyanide compound, or a dicyanide compound; or

[0018] (d) the electrolyte further comprises at least one of lithium hexafluorophosphate, lithium bis(trifluoromethane) sulfonimide, lithium bis(fluorosulfonyl) imide, or lithium difluorophosphate.

[0019] In some embodiments, the electrolyte satisfies at least one of the following conditions:

[0020] a) the mass percentage content of the 1,3-propane sultone is 0.5% to 5%, based on the total mass of the electrolyte;

[0021] b) the mass percentage content of the vinyl sulfate is 0.1% to 1%, based on the total mass of the electrolyte;

[0022] c) the mass percentage content of the vinylene carbonate is 0.1% to 1%, based on the total mass of the electrolyte;

[0023] d) the mass percentage content of the bicyclic carbonate compound is 0.1% to 30%, based on the total mass of the electrolyte;

[0024] e) a mass percentage of the bicyclic sulfate compound is 0.1% to 5% based on a total mass of the electrolyte;

[0025] f) a mass percentage of the trinitrile compound is 0.1% to 10% based on a total mass of the electrolyte; or

[0026] j) a mass percentage of the dinitrile compound is 0.1% to 10% based on a total mass of the electrolyte.

[0027] In some embodiments, the carboxylic acid ester comprises at least one of methyl acetate, ethyl acetate, propyl acetate, ethyl propionate, propyl propionate, butyl propionate, pentyl propionate, methyl halogenoacetate, ethyl halogenoacetate, propyl halogenoacetate, ethyl halogenopropionate, propyl halogenopropionate, butyl halogenopropionate, or pentyl halogenopropionate.

[0028] Without being limited by any theory, the introduction of the carboxylic acid ester can significantly reduce the viscosity of the electrolyte, improve the conductivity of the electrolyte, and thus improve the transmission rate of lithium ions in the battery, reduce the polarization of the battery, and compensate for the deterioration of the kinetics and room temperature performance of the doped elements of the positive electrode.

[0029] Without being limited by any theory, adjusting the amount of ethylene carbonate and propylene carbonate can strengthen the interface protection of the negative electrode, reduce the consumption rate of the electrolyte, and further enhance the thermal stability and high-temperature cycle stability of the lithium ion battery. Without being limited by any theory, by adjusting the content of the above electrolyte additives within the scope of the present application, the interface film can be further strengthened, and the thermal stability of the lithium ion battery can be further improved.

[0030] In some embodiments, the electrochemical device further comprises a separator, the separator comprising a porous substrate and a porous coating disposed on at least one surface of the porous substrate, wherein the porous coating comprises inorganic particles and a binder.

[0031] In some embodiments, the separator satisfies at least one of the following:

[0032] (a) the inorganic particles in the porous coating comprise at least one of magnesium hydroxide, boehmite, or aluminum trioxide;

[0033] (b) the binder in the porous coating comprises polyvinylidene fluoride; or

[0034] (c) a thickness of the porous coating is T pm, 1≤T≤5.

[0035] In another embodiment, the present application provides an electronic device comprising the electrochemical device according to embodiments of the present application.

[0036] The electrochemical device provided by the application has high thermal stability at high voltage, high temperature cycle stability and improved thermal box performance.

[0037] Additional layers and advantages of the embodiments of the application will be described and will become further apparent to those of ordinary skill in the art by the following detailed description, the appended claims, and the drawings. DETAILED DESCRIPTION

[0038] In order to make the objects, technical solutions, and advantages of the present application clearer, the following further describes the present application with reference to the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. Based on the embodiments in the present application, all other technical solutions obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0039] The embodiments of the present application will be described in detail in the following. The embodiments of the present application should not be interpreted as a limitation of the present application.

[0040] In addition, quantities, ratios, and other numerical values are sometimes presented in range format in this document. It should be understood that such range format is used for convenience and brevity and should be construed as having been followed had each value from the range was individually listed.

[0041] In the DETAILED DESCRIPTION and in the claims, a list of items joined by the term "one of" or "one of each" or other similar term means any single one of the listed items. For example, if A and B are listed, the phrase "one of A and B" means A alone or B alone. In another example, if A, B, and C are listed, the phrase "one of A, B, and C" means A alone; B alone; or C alone. Item A can include a single element or multiple elements. Item B can include a single element or multiple elements. Item C can include a single element or multiple elements.

[0042] In the DETAILED DESCRIPTION and in the claims, a list of items joined by the term "at least one of" or "at least one" or other similar term means any combination of the listed items. For example, if A and B are listed, the phrase "at least one of A and B" means A alone; B alone; or A and B. In another example, if A, B, and C are listed, the phrase "at least one of A, B, and C" means A alone; or B alone; or C alone; A and B (excluding C); A and C (excluding B); B and C (excluding A); or A, B, and C. Item A can include a single element or multiple elements. Item B can include a single element or multiple elements. Item C can include a single element or multiple elements.

[0043] I. Electrochemical device

[0044] In some embodiments, the present application provides an electrochemical device, comprising: a positive electrode comprising a positive electrode active material, the positive electrode active material comprising metal elements Co and Mn, wherein a mass percentage content of Mn is B% based on a total mass of the positive electrode active material; and an electrolyte comprising a boron-containing lithium salt, wherein a mass percentage content of the boron-containing lithium salt is C% based on a total mass of the electrolyte; wherein 0.05≤C≤1 and 0.01≤C / 10B≤2.

[0045] In some embodiments, the electrochemical device satisfies at least one of the following conditions: (a) 0.1≤C≤1; or (b) 0.05≤C / 10B≤1.

[0046] In some embodiments, C is 0.05, 0.08, 0.1, 0.3, 0.5, 0.8, 1, or a range between any two of these values.

[0047] In some embodiments, C / 10B is 0.01, 0.03, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4, 0.5, 0.8, 1, 1.5, 1.8, 2.0, or a range between any two of these values.

[0048] In some embodiments, 0.05≤B≤0.5. In some embodiments, B is 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.5, or a range between any two of these values.

[0049] In some embodiments, a mass percentage content of Co is A% based on a total mass of the positive electrode active material, and 10≤A≤90. In some embodiments, A is 10, 20, 30, 40, 50, 55, 58, 60, 62, 65, 70, 80, 90, or a range between any two of these values.

[0050] In some embodiments, 6≤A / 20B≤60. In some embodiments, A / 20B is 6, 8, 10, 12, 15, 18, 20, 25, 28, 30, 32, 35, 40, 45, 50, 55, 60, or a range between any two of these values.

[0051] In some embodiments, the positive electrode active material comprises Li α Co 1-x-y Mn x M y O βwherein M comprises one or more of Mg, Al, Ca, Ti, Zr, V, Cr, Fe, Ni, Cu, Zn, Ru, or Sn, wherein 0.95 < a < 1.4, 0 < x < 0.4, 0 < y < 0.3, and 1.90 < β < 2.10.

[0052] In some embodiments, the positive active material comprises lithium cobaltate.

[0053] In some embodiments, the boron-containing lithium salt comprises at least one of lithium bis(l,l-trifluoromethyl oxalate) borate, lithium bis(l-trifluoromethyl oxalate) borate, lithium difluoro(l,l-trifluoromethyl)oxalate borate, lithium difluoro oxalate borate, lithium dioxalate borate, lithium bis(l,l-trifluoromethyl malonate) borate, lithium fluoromalonate difluoroborate, or lithium bis(fluoromalonate) borate.

[0054] In some embodiments, the boron-containing lithium salt comprises at least one of LiDFOB or LiBOB.

[0055] In some embodiments, the electrolyte satisfies at least one of:

[0056] (a) the electrolyte further comprises a carboxylic acid ester, wherein the mass percentage content of the carboxylic acid ester is X% based on the total mass of the electrolyte, 10 < X < 60;

[0057] (b) the electrolyte further comprises vinyl carbonate and propylene carbonate, wherein the mass percentage content of the vinyl carbonate is D% and the mass percentage content of the propylene carbonate is E% based on the total mass of the electrolyte, wherein 5 < D + E < 40, and D > E;

[0058] (c) the electrolyte further comprises at least one of 1,3-propane sultone, vinyl sulfate, vinylene carbonate, a bicyclic carbonate compound, a bicyclic sulfate compound, a tricyanide compound, or a dicyanide compound; or

[0059] (d) the electrolyte further comprises at least one of lithium hexafluorophosphate, lithium bis(trifluoromethane)sulfonimide, lithium bis(fluorosulfonyl)imide, or lithium difluorophosphate.

[0060] In some embodiments, X is 10, 15, 20, 22, 28, 30, 32, 34, 36, 40, 50, 60, or a range between any two of these values.

[0061] In some embodiments, the electrolyte satisfies at least one of the following conditions:

[0062] a) the mass percentage content of the 1,3-propane sultone is 0.5% to 5% based on the total mass of the electrolyte;

[0063] b) a mass percentage of the vinylsulfate of 0.1% to 1% based on the total mass of the electrolyte;

[0064] c) a mass percentage of the vinylene carbonate of 0.1% to 1% based on the total mass of the electrolyte;

[0065] d) a mass percentage of the bicyclic carbonate compound of 0.1% to 30% based on the total mass of the electrolyte;

[0066] e) a mass percentage of the bicyclic sulfate compound of 0.1% to 5% based on the total mass of the electrolyte;

[0067] f) a mass percentage of the trinitrile compound of 0.1% to 10% based on the total mass of the electrolyte; or

[0068] j) a mass percentage of the dinitrile compound of 0.1% to 10% based on the total mass of the electrolyte.

[0069] In some embodiments, the mass percentage of the 1,3-propane sultone is 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or a range consisting of any two of these values, based on the total mass of the electrolyte.

[0070] In some embodiments, the mass percentage of the vinylsulfate is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or a range consisting of any two of these values, based on the total mass of the electrolyte.

[0071] In some embodiments, the mass percentage of the vinylene carbonate is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or a range consisting of any two of these values, based on the total mass of the electrolyte.

[0072] In some embodiments, the mass percentage of the bicyclic carbonate compound is 0.1%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, or a range consisting of any two of these values, based on the total mass of the electrolyte.

[0073] In some embodiments, the mass percent of the bicyclic sulfate compound is 0.1%, 0.5%, 1%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or a range of any two of these values, based on the total mass of the electrolyte. In some embodiments, the carboxylic acid ester comprises at least one of methyl acetate, ethyl acetate, propyl acetate, ethyl propionate, propyl propionate, butyl propionate, pentyl propionate, methyl haloacetate, ethyl haloacetate, propyl haloacetate, ethyl halo-propionate, propyl halo-propionate, butyl halo-propionate, or pentyl halo-propionate.

[0074] In some embodiments, the carboxylic acid ester comprises ethyl propionate and propyl propionate.

[0075] In some embodiments, the carboxylic acid ester comprises ethyl propionate, propyl propionate, and ethyl acetate.

[0076] In some embodiments, 5 < D < 40. In some embodiments, D is 5, 7, 10, 15, 18, 20, 25, 30, 35, 38, 40, or a range of any two of these values.

[0077] In some embodiments, 0 < E < 30. In some embodiments, E is 0, 5, 8, 10, 15, 18, 20, 25, 30, or a range of any two of these values.

[0078] In some embodiments, D > E.

[0079] In some embodiments, D + E is 5, 7, 10, 15, 18, 20, 25, 30, 35, 38, 40, or a range of any two of these values.

[0080] In some embodiments, the trinitrile compound comprises at least one of 1,3,5- pentanetricarbonitrile, 1,2,3-propanetricarbonitrile, 1,3,6-hexanetricarbonitrile, 1,2,6- hexanetricarbonitrile, 1,2,3-tris(2-cyanoethoxy)propane, 1,2,4-tris(2- cyanoethoxy)butane, or 1,2,5-tris(cyanoethoxy)pentane.

[0081] In some embodiments, the dinitrile compound comprises at least one of butanedinitrile, pentanedinitrile, hexanedinitrile, 1,5-dicyanopentane, 1,6- dicyanohexane, 1,7-dicyanoheptane, 1,8-dicyanoctane, 1,9- dicyanononane, 1,10-dicyanodecane, 1,12-dicyanododecane, tetramethyl butanedinitrile, 2-methylpentanedinitrile, 2,4-dimethylpentanedinitrile, 2,2,4,4- tetramethylpentanedinitrile.

[0082] In some embodiments, the tri-nitrile compound has a mass percentage content of 0-10% based on the total mass of the electrolyte. In some embodiments, the tri-nitrile compound has a mass percentage content of 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a range consisting of any two of these values.

[0083] In some embodiments, the di-nitrile compound has a mass percentage content of 0-10% based on the total mass of the electrolyte. In some embodiments, the di-nitrile compound has a mass percentage content of 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a range consisting of any two of these values.

[0084] In some embodiments, the lithium hexafluorophosphate, lithium bis(trifluoromethane)sulfonimide, lithium bis(fluorosulfonyl)imide, or lithium difluorophosphate has a mass percentage content of 0.1-15%. In some embodiments, the lithium hexafluorophosphate, lithium bis(trifluoromethane)sulfonimide, lithium bis(fluorosulfonyl)imide, or lithium difluorophosphate has a mass percentage content of 0.1%, 0.3%, 0.5%, 1%, 1.5%, 1.8%, 2.0%, 2.5%, 3%, 5%, 8%, 10%, 12%, 15%, or a range consisting of any two of these values.

[0085] In some embodiments, the electrolyte further includes diethyl carbonate (DEC). In some embodiments, the diethyl carbonate has a mass percentage content of 20-70% based on the total mass of the electrolyte. In some embodiments, the diethyl carbonate has a mass percentage content of 20%, 30%, 40%, 50%, 60%, 70%, or a range consisting of any two of these values, based on the total mass of the electrolyte.

[0086] In some embodiments, the positive electrode further includes a conductive agent. In some embodiments, the conductive agent includes at least one of carbon nanotubes, carbon fibers, acetylene black, graphene, ketjen black, or carbon black.

[0087] In some embodiments, the positive electrode further includes a binder. In some embodiments, the binder includes at least one of polyvinylidene fluoride, carboxymethyl cellulose, styrene butadiene rubber, polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1,1- difluoroethylene, polyethylene, polypropylene, acrylated styrene butadiene rubber, epoxy resin, or nylon.

[0088] In some embodiments, the current collector includes at least one of a copper foil or an aluminum foil.

[0089] In some embodiments, the cathode can be prepared by a preparation method known in the art. For example, the cathode can be obtained by mixing a cathode active material, a conductive agent, and a binder in a solvent to prepare an active material composition, and coating the active material composition on a current collector. In some embodiments, the solvent can include N-methylpyrrolidone, etc., but is not limited thereto.

[0090] In some embodiments, the electrochemical device includes any device in which an electrochemical reaction occurs.

[0091] In some embodiments, the electrochemical device is a lithium secondary battery.

[0092] In some embodiments, the lithium secondary battery includes, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery, a full solid-state secondary lithium battery.

[0093] negative electrode

[0094] In some embodiments, the material, the constitution, and the manufacturing method of the negative electrode used in the electrochemical device of the present application can include any of the techniques disclosed in the prior art. In some embodiments, the negative electrode is the negative electrode described in U.S. Patent Application US9812739B, which is incorporated herein by reference in its entirety.

[0095] In some embodiments, the negative electrode includes a current collector and a negative electrode active material layer on the current collector. In some embodiments, the negative electrode active material layer includes a negative electrode active material. In some embodiments, the negative electrode active material includes, but is not limited to, lithium metal, structured lithium metal, natural graphite, artificial graphite, meso-carbon microbe (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, silicon-oxygen material (e.g., SiO, SiO2), Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, spinel-structured lithiated TiO2-Li4Ti5O12, Li-Al alloy, or any combination thereof. 12

[0096] In some embodiments, the negative electrode active material layer includes a binder. In some embodiments, the binder includes, but is not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylated styrene butadiene rubber, epoxy resin, or nylon.

[0097] ​In some embodiments, the negative active material layer includes a conductive material. In some embodiments, the conductive material includes, but is not limited to, natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, metal powder, metal fiber, copper, nickel, aluminum, silver, or polyphenylene derivative.

[0098] In some embodiments, the current collector includes, but is not limited to, copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or polymer substrate coated with a conductive metal.

[0099] In some embodiments, the negative electrode can be obtained by mixing an active material, a conductive material, and a binder in a solvent to prepare an active material composition, and coating the active material composition on a current collector.

[0100] In some embodiments, the solvent can include, but is not limited to, deionized water, N-methylpyrrolidone.

[0101] In some embodiments, the negative electrode in the all-solid-state secondary lithium battery is a metal lithium foil.

[0102] separator

[0103] In some embodiments, the electrochemical device further includes a separator between the positive electrode and the negative electrode, the separator including a porous substrate and a porous coating layer disposed on at least one surface of the porous substrate, wherein the porous coating layer includes inorganic particles and a binder.

[0104] In some embodiments, one surface of the porous substrate is provided with a porous coating layer. In some embodiments, both surfaces of the porous substrate are provided with a porous coating layer.

[0105] In some embodiments, the separator satisfies at least one of the following conditions:

[0106] (a) the inorganic particles in the porous coating layer include at least one of magnesium hydroxide, boehmite, or aluminum trioxide;

[0107] (b) the binder in the porous coating layer includes polyvinylidene fluoride (PVDF); or

[0108] (c) the thickness of the porous coating layer is T μm, 1 ≤ T ≤ 5.

[0109] In some embodiments, T is 1, 2, 3, 4, 5, or a range consisting of any two of these values.

[0110] In some embodiments, the material and shape of the separator used in the electrochemical device of the present application are not particularly limited and can be any of the technologies disclosed in the prior art.

[0111] In some embodiments, the porous substrate can be selected from one or more of a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite membrane.

[0112] In some embodiments, the mass percentage of the fluorine-containing binder is 10-70%, based on the total mass of the inorganic particles and the fluorine-containing binder in the porous coating. In some embodiments, the mass percentage of the fluorine-containing binder is 10%, 20%, 30%, 40%, 50%, 60%, 70%, or a range consisting of any two of these values, based on the total mass of the inorganic particles and the fluorine-containing binder in the porous coating.

[0113] In some embodiments, the mass percentage of the inorganic particles is 30-90%, based on the total mass of the inorganic particles and the fluorine-containing binder in the porous coating. In some embodiments, the mass percentage of the inorganic particles is 30%, 40%, 50%, 60%, 70%, 80%, 90%, or a range consisting of any two of these values, based on the total mass of the inorganic particles and the fluorine-containing binder in the porous coating. The porous coating can improve the heat resistance, oxidation resistance, and electrolyte wettability of the separator film, and enhance the adhesion between the separator film and the electrode sheet.

[0114] In some embodiments, the binder is selected from one or more of a combination of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene, and polyhexafluoropropylene.

[0115] electrolyte

[0116] In some embodiments, the electrolyte used in the electrolyte of the embodiments of the present application can be an electrolyte known in the art, including, but not limited to, inorganic lithium salts such as LiClO4, LiPF6, LiBF4, LiSbF6, LiSO3F, LiN(FSO2)2, and the like; fluorine-containing organic lithium salts such as LiCF3SO3, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, cyclic 1,3-hexafluoropropanedisulfonimide lithium, cyclic 1,2-tetrafluoroethane disulfonimide lithium, LiN(CF3SO2)(C4F9SO2), LiC(CF3SO2)3, LiPF4(CF3)2, LiPF4(C2F5)2, LiPF4(CF3SO2)2, LiPF4(C2F5SO2)2, LiBF2(CF3)2, LiBF2(C2F5)2, LiBF2(CF3SO2)2, LiBF2(C2F5SO2)2; dicarboxylic acid complex-containing lithium salts such as lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tris(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, lithium tetrafluoro(oxalato)phosphate, and the like. In addition, the above electrolytes can be used singly, or two or more kinds can be used simultaneously. For example, in some embodiments, the electrolyte includes a combination of LiPF6and LiBF4. In some embodiments, the electrolyte includes a combination of an inorganic lithium salt such as LiPF6or LiBF4and a fluorine-containing organic lithium salt such as LiCF3SO3, LiN(CF3SO2)2, LiN(C2F5SO2)2, and the like. In some embodiments, the concentration of the electrolyte is in the range of 0.8 to 3 mol / L, such as in the range of 0.8 to 2.5 mol / L, in the range of 0.8 to 2 mol / L, in the range of 1 to 2 mol / L, 0.5 to 1.5 mol / L, 0.8 to 1.3 mol / L, 0.5 to 1.2 mol / L, and for example, 1 mol / L, 1.15 mol / L, 1.2 mol / L, 1.5 mol / L, 2 mol / L, or 2.5 mol / L.

[0117] The process of preparing the electrochemical device is well known to those skilled in the art, and the present application is not particularly limited. For example, a lithium ion battery can be manufactured by overlapping the positive electrode and the negative electrode via a separator film, and placing it in a case after performing operations such as winding, folding, and the like as necessary, injecting an electrolyte into the case and sealing. In addition, a current overflow prevention element, a guide plate, and the like can be placed in the case as necessary, thereby preventing the pressure inside the lithium ion battery from rising, overcharging, and overdischarging.

[0118] II. Electronic device

[0119] The electronic device of the present application can be any device that uses an electrochemical device according to the embodiments of the present application.

[0120] In some embodiments, the electronic device includes, 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 copying machine, a portable printer, a head-mounted stereo headphone, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic notebook, 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 timepiece, an electric tool, a flash, a camera, a household large storage battery, or a lithium ion capacitor, etc.

[0121] The preparation of the lithium ion battery will be described below with the lithium ion battery as an example and in connection with specific embodiments. Those skilled in the art will understand that the preparation methods described in the present application are only examples, and any other suitable preparation method is within the scope of the present application.

[0122] Embodiments

[0123] The following examples and comparative examples are given to more specifically explain the embodiments of the present application. Various tests and evaluations were performed according to the following methods. In addition, unless otherwise specified, "parts" and "%" are on a mass basis.

[0124] I. Test methods and equipment:

[0125] (1) Positive active material Co, Mn metal element content test:

[0126] The active material of the positive electrode sheet cleaned with DMC (dimethyl carbonate) is scraped off with a doctor blade, dissolved with a mixed solvent (for example, 0.4 g of positive active material is dissolved with 10 ml of aqua regia (nitric acid and hydrochloric acid mixed at 1:1) and 2 ml of HF), made up to 100 mL, and then the content of Co, Mn and other metal elements in the solution is tested using an ICP analyzer, with the unit being %.

[0127] (2) Lithium ion battery high-temperature cycle performance test:

[0128] At 45°C, the lithium ion battery is charged at 0.7C (rate) to 4.5V, then charged at constant voltage until the current is 0.05C, and then discharged at 1C to 3.0V. This process is one charge-discharge cycle, which is the first cycle at this time. The discharge capacity of the lithium ion battery in the first cycle is recorded. The lithium ion battery is subjected to charge-discharge cycles according to the above method, and the discharge capacity of each cycle is recorded until the discharge capacity of the lithium ion battery decays to 80% of the discharge capacity of the first cycle, and the number of charge-discharge cycles is recorded.

[0129] (3) Lithium ion battery room temperature cycle performance test:

[0130] The lithium ion battery was charged at 0.7 C (rate) to 4.5 V at 25 °C, then charged at constant voltage to the current of 0.05 C, and then discharged at 1 C to 3.0 V, which was one charge-discharge cycle. At this time, it was the first cycle, and the discharge capacity of the lithium ion battery in the first cycle was recorded. The lithium ion battery was charged and discharged according to the above method, and the discharge capacity of each cycle was recorded until the discharge capacity of the lithium ion battery decayed to 80% of the discharge capacity in the first cycle, and the number of charge-discharge cycles was recorded.

[0131] (4) Lithium ion battery hot box (Hotbox) safety test:

[0132] The full charge of the cell was completed before thermal shock, and the appearance was checked and photographed before and after the test. The temperature sensing wire was attached to the center of the cell surface. The sample was placed vertically in the box, and the temperature was raised to the required test temperature (130 / 135) ± 2 °C at a temperature rise rate of 2 ± 2 °C, and maintained for 60 min. Measurement frequency: 1 KHz specification was used for voltage and resistance measurement, and measurement was performed after pretreatment and after test. Test judgment standard: no fire, no explosion is passed. Among them, "5 / 10 Pass" means that 10 batteries are tested for each example, and five of them pass the test.

[0133] II. Preparation of lithium ion battery

[0134] Examples 1-9 and Comparative Examples 1-3

[0135] (1) Preparation of modified positive active material:

[0136] Commercial lithium cobalt oxide (LiCoO2) and trimanganese tetroxide (Mn3O4) were mixed, mixed in a high-speed mixer at 300 r / min for 20 min, and then placed in an air kiln furnace, heated to 820 °C at a rate of 5 °C / min, and kept for 24 h. After natural cooling, the modified positive active material (i.e. modified LiCoO2) was obtained by passing through a 300 mesh sieve. The total content of metal elements Mn and Co in the modified positive active material is shown in Table 1.

[0137] (2) Preparation of positive electrode sheet

[0138] The modified LiCoO2, conductive agent carbon nanotube (CNT), and binder polyvinylidene fluoride were mixed in a mass ratio of 95:2:3, N-methyl pyrrolidone (NMP) was added as a solvent, and the system was stirred in a vacuum stirrer until the positive electrode slurry was homogeneous and the solid content was 75 wt%. The positive electrode slurry was uniformly coated on a positive electrode current collector aluminum foil with a thickness of 12 μm, dried at 85°C, and cold-pressed to obtain a positive electrode tab with a positive electrode active material layer thickness of 100 μm. Then the above steps were repeated on the other surface of the positive electrode tab to obtain a positive electrode tab coated with positive electrode active material layers on both sides. The positive electrode tab was cut into a size of 74 mm x 867 mm and the tab was welded for use.

[0139] (3) Preparation of the negative electrode tab

[0140] The negative electrode active material artificial graphite, styrene butadiene rubber (SBR), and carboxymethyl cellulose (CMC) were mixed in a mass ratio of 95:2:3, and then deionized water was added as a solvent to prepare a slurry with a solid content of 70 wt% and stirred uniformly. The slurry was uniformly coated on one surface of a copper foil with a thickness of 8 μm, dried at 110°C, and cold-pressed to obtain a negative electrode tab with a single-side coated negative electrode active material layer with a thickness of 150 μm. Then the above coating steps were repeated on the other surface of the negative electrode tab to obtain a negative electrode tab coated with negative electrode active material layers on both sides. The negative electrode tab was cut into a size of (74 mm x 867 mm) and the tab was welded for use. The defect degree Id / Ig of the negative electrode tab was 0.17.

[0141] (4) Preparation of the electrolyte

[0142] In an argon atmosphere glove box with a water content of less than 10 ppm, ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) were uniformly mixed in a mass ratio of 20:20:60 as a base solvent, lithium hexafluorophosphate (LiPF6) and a lithium salt containing boron were added to the base solvent and stirred uniformly to form an electrolyte. The mass percentage of LiPF6 was 12.5% based on the total mass of the electrolyte, and the specific type and mass percentage of the lithium salt containing boron are shown in Table 1. The sum of the contents of each substance in the electrolyte was 100%.

[0143] LiDFOB in Table 1 represents lithium difluoro(oxalato)borate, and LiBOB represents lithium bis(oxalato)borate.

[0144] (5) Preparation of the separator

[0145] A polyethylene (PE) porous polymer film with a thickness of 12 μm is used as the separator, and a porous coating composed of Al2O3 and PVDF is coated on both surfaces of the base film, the thickness of the porous coating being 3 μm. The mass content of Al2O3 in the porous coating is 70%, and the content of PVDF in the porous coating is 30%.

[0146] (6) Preparation of the lithium ion battery

[0147] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order with the separator between the positive electrode sheet and the negative electrode sheet to play a role of isolation, and are wound to obtain an electrode assembly. The electrode assembly is put into an aluminum plastic film packaging bag, and is dehydrated at 80°C. The electrolyte solution prepared is injected, and the lithium ion battery is obtained through processes such as vacuum packaging, standing, formation, and shaping.

[0148] Examples 10-14

[0149] Preparation of the electrolyte solution:

[0150] In an argon glove box with a water content of less than 10 ppm, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and carboxylic acid ester are uniformly mixed in a mass ratio of 20:20:(60-X):X as a base solvent. LiPF6 and a lithium salt containing boron are added to the base solvent and stirred uniformly to form an electrolyte solution. The mass percentage content of the lithium salt containing boron is 0.5% and the mass percentage content of LiPF6 is 12.5% based on the total mass of the electrolyte solution. The types and mass percentage contents of the carboxylic acid esters and the changes in the related preparation parameters and properties are shown in Table 2. The content of the carboxylic acid ester in Table 2 is calculated based on the total mass of the base solvent. The sum of the contents of the substances in the electrolyte solution is 100%.

[0151] Except that the preparation of the electrolyte solution is different from that of Example 6, the rest is the same as that of Example 6.

[0152] Examples 15-20

[0153] Preparation of the electrolyte solution:

[0154] In an argon glove box with a water content of less than 10 ppm, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and / or propyl propionate (PP) are uniformly mixed as a base solvent. LiPF6 and a lithium salt containing boron are added to the base solvent and stirred uniformly to form an electrolyte solution. The mass percentage content of the lithium salt containing boron is 0.5% and the mass percentage content of LiPF6 is 12.5% based on the total mass of the electrolyte solution. The mass percentage contents of other substances and the changes in the related preparation parameters and properties are shown in Table 3. The contents of EC, PC, and PP in Table 3 are calculated based on the total mass of the base solvent. The sum of the contents of the substances in the electrolyte solution is 100%.

[0155] The preparation of the electrolyte is different from that of Example 6, and the rest is the same as that of Example 6.

[0156] Examples 21-23

[0157] Preparation of the electrolyte:

[0158] In an argon atmosphere glove box with water content less than 10 ppm, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC) and / or propyl propionate (PP) were uniformly mixed as a base solvent, LiPF6, lithium bis(oxalato)borate (LiBOB) and 1,3,6-hexanetricarbonitrile were added into the base solvent, and stirred uniformly to form an electrolyte, wherein the mass percentage of LiPF6 was 12.5% and the mass percentage of the lithium boron-containing salt was 0.5% based on the total mass of the electrolyte, and the specific mass percentage and performance of other substances were shown in Table 4. The content of EC, PC and PP in Table 4 was calculated based on the total mass of the base solvent. The mass content of 1,3,6-hexanetricarbonitrile in Table 4 was calculated based on the total mass of the electrolyte. The sum of the content of each substance in the electrolyte was 100%.

[0159] The preparation of the electrolyte is different from that of Example 6, and the rest is the same as that of Example 6.

[0160] Examples 24-27

[0161] In an argon atmosphere glove box with water content less than 10 ppm, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC) and / or propyl propionate (PP) were uniformly mixed as a base solvent, LiPF6, lithium bis(oxalato)borate (LiBOB) and / or 1,3,6-hexanetricarbonitrile were added into the base solvent, and stirred uniformly to form an electrolyte, wherein the mass percentage of LiPF6 was 12.5% and the mass percentage of the lithium boron-containing salt was 0.5% based on the total mass of the electrolyte, and the specific mass percentage and performance of other substances were shown in Table 5. The content of EC, PC and PP in Table 5 was calculated based on the total mass of the base solvent. The mass content of 1,3,6-hexanetricarbonitrile in Table 5 was calculated based on the total mass of the electrolyte. The sum of the content of each substance in the electrolyte was 100%.

[0162] Preparation of the separator:

[0163] A polyethylene (PE) porous polymer film with a thickness of 12 μm was used as the separator, and a porous coating layer composed of Al2O3 and PVDF was coated on both surfaces of the base film, and the thickness of the porous coating layer was shown in Table 5. The mass content of Al2O3 in the porous coating layer was 70%, and the content of PVDF in the porous coating layer was 30%.

[0164] The rest is the same as Example 6 except for the preparation of the separator and the electrolyte.

[0165] Table 1

[0166]

[0167]

[0168] As can be seen from Examples 1 to 9 and Comparative Examples 1 to 3 in Table 1, by adjusting C / 10B within the scope of the present application, the 130°C hot box passing rate and the 135°C hot box passing rate of the lithium ion battery are significantly improved. Without being limited to any theory, this can be due to the stability of Mn to O, which in turn improves the structural stability of the positive electrode material. However, it is found that with the further increase of the content of Mn element, the negative electrode thermal stability is deteriorated, but by introducing a boron-containing lithium salt into the electrolyte, the thermal stability of the positive electrode and the negative electrode can be considered, and it is found that when C / 10B is within the above range, the effect is most obvious. Without being limited to any theory, this can be due to the introduction of the above-mentioned boron-containing lithium salt, which inhibits the dissolution of manganese ions, and improves the thermal stability, hydrolysis stability and oxidation stability of the electrolyte, which makes up for the deterioration of the dissolution of the metal element doped positive electrode material. In addition, the electrolyte containing lithium bis(oxalato)borate (LiBOB) has the following characteristics: it can form a stable and effective passivation film in propylene carbonate (PC) solution, it does not corrode the aluminum foil current collector, and the discharge capacity does not decay under high temperature conditions, thereby achieving the balance of the thermal stability of the positive and negative electrodes.

[0169] Table 2

[0170]

[0171] As can be seen from Examples 10 to 14 in Table 2, the introduction of an appropriate amount of carboxylic acid ester into the electrolyte can improve the high-temperature cycle stability and room-temperature cycle stability of the lithium ion battery. Without being limited to any theory, the introduction of carboxylic acid ester can significantly reduce the viscosity of the electrolyte, improve the electrical conductivity of the electrolyte, and thus improve the transmission rate of lithium ions in the battery, reduce the polarization of the battery, and make up for the deterioration of the kinetics and room-temperature performance of the doped elements of the positive electrode.

[0172] Table 3

[0173]

[0174] As can be seen from Examples 15 to 20 in Table 3, when D, E are within the scope of the present application, the lithium ion battery can obtain better cycle performance. Without being limited to any theory, adjusting the amount of ethylene carbonate and propylene carbonate can strengthen the interface protection of the negative electrode, reduce the consumption rate of the electrolyte, and further enhance the thermal stability and high-temperature cycle stability of the lithium ion battery. Without being limited to any theory, by adjusting the above-mentioned electrolyte additives within the scope of the present application, the interface film can be further strengthened, and the thermal stability of the lithium ion battery can be further improved.

[0175] Table 4

[0176]

[0177] As can be seen from Examples 21 to 23 in Table 4, adding a nitrile additive such as 1,3,6-hexanetricarbonitrile to the electrolyte can further improve the cycle stability of the lithium ion battery. Without being limited to any theory, the cyano group in the nitrile additive has strong coordination ability and can be combined with active sites on the electrode surface, such as tetravalent cobalt ions in high valence state, to mask these active ions on the positive electrode surface, reduce the decomposition of the electrolyte by the electrode, reduce side reactions, and thus improve the cycle performance.

[0178] Table 5

[0179]

[0180] As can be seen from Examples 24-27 in Table 5, when the porous coating thickness of the separator is 1-5 μm, the high-temperature and room-temperature cycle performance of the lithium ion battery can be further improved.

[0181] Throughout this specification, the use of “some embodiments”, “particular embodiments”, “one embodiment”, “another embodiment”, “an embodiment”, “certain embodiments”, or “some embodiments” can mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. Therefore, the appearance of the phrases such as “in some embodiments”, “in embodiments”, “in one embodiment”, “in another embodiment”, “in an embodiment”, “in certain embodiments”, or “in some embodiments” appearing in various places throughout the specification is not necessarily referring to the same embodiment or example of the application. In addition, the specific features, structures, materials, or characteristics described herein can be combined in any suitable manner in one or more embodiments or examples.

[0182] Although the illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments cannot be interpreted as limiting the application, and changes, substitutions and modifications can be made to the embodiments without departing from the spirit, principles and scope of the application.

Claims

1. An electrochemical device comprising: A positive electrode, comprising a positive electrode active material, the positive electrode active material containing the metal elements Co and Mn, wherein, based on the total mass of the positive electrode active material, the mass percentage of Mn is B%, and 0.05 ≤ B ≤ 0.5; and The electrolyte comprises a boron-containing lithium salt, wherein the boron-containing lithium salt has a mass percentage content of C% based on the total mass of the electrolyte. The boron-containing lithium salt includes at least one of lithium di(1,1-trifluoromethyloxalic acid)borate, lithium di(1-trifluoromethyloxalic acid)borate, lithium difluoro(1,1-trifluoromethyl)oxalateborate, lithium difluorooxalateborate, lithium dioxalateborate, lithium dioxalateborate, lithium di(1,1-trifluoromethylmalonic acid)borate, lithium difluoromalonic acid difluoroborate, or lithium di(fluoromalonic acid)borate. Where 0.05≤C≤1, and 0.01≤C / 10B≤2.

2. The electrochemical device according to claim 1, wherein, The electrochemical device satisfies at least one of the following conditions: (a) 0.1 ≤ C ≤ 1; (b) 0.05≤C / 10B≤1.

3. The electrochemical device according to claim 1, wherein, Based on the total mass of the positive electrode active material, the mass percentage of Co is A%, 6≤A / 20B≤60.

4. The electrochemical device according to claim 1, wherein, The positive electrode active material includes Li α Co 1-x-y Mn x M y O β , where M includes one or more of Mg, Al, Ca, Ti, Zr, V, Cr, Fe, Ni, Cu, Zn, Ru or Sn, where 0.95 ≤ α ≤ 1.4, 0 < x ≤ 0.4, 0 ≤ y ≤ 0.3 and 1.90 ≤ β ≤ 2.

10.

5. The electrochemical device according to claim 1, wherein, The electrolyte satisfies at least one of the following: (a) The electrolyte further includes a carboxylic acid ester, wherein the mass percentage of the carboxylic acid ester is X% based on the total mass of the electrolyte, and 10 ≤ X ≤ 60; (b) The electrolyte further includes ethylene carbonate and propylene carbonate, wherein, based on the total mass of the electrolyte, the mass percentage of ethylene carbonate is D%, and the mass percentage of propylene carbonate is E%, wherein 5 ≤ D + E ≤ 40, and D ≥ E; (c) The electrolyte further comprises at least one of 1,3-propanesulfonyl lactone, vinyl sulfate, vinylene carbonate, bicyclic carbonate compound, bicyclic sulfate compound, trinitrile compound, or dinitrile compound; or (d) The electrolyte further includes at least one of lithium hexafluorophosphate, lithium bis(trifluoromethane)sulfonylimide, lithium bis(fluorosulfonylimide) or lithium difluorophosphate.

6. The electrochemical device according to claim 5, wherein the carboxylic acid ester comprises at least one of methyl acetate, ethyl acetate, propyl acetate, ethyl propionate, propyl propionate, butyl propionate, pentyl propionate, methyl haloacetate, ethyl haloacetate, propyl haloacetate, ethyl halopropionate, propyl halopropionate, butyl halopropionate, or pentyl halopropionate.

7. The electrochemical device according to claim 5, wherein the electrolyte satisfies at least one of the following conditions: a) Based on the total mass of the electrolyte, the mass percentage of the 1,3-propanesulfonyl lactone is 0.5% to 5%; b) Based on the total mass of the electrolyte, the mass percentage of the vinyl sulfate is 0.1% to 1%; c) Based on the total mass of the electrolyte, the mass percentage of vinylene carbonate is 0.1% to 1%; d) Based on the total mass of the electrolyte, the mass percentage of the bicyclic carbonate compound is from 0.1% to 30%; e) Based on the total mass of the electrolyte, the mass percentage of the bicyclic sulfate compound is 0.1% to 5%; f) Based on the total mass of the electrolyte, the mass percentage of the trinitrile compound is 0.1% to 10%; or j) Based on the total mass of the electrolyte, the mass percentage of the dinitrile compound is 0.1% to 10%.

8. The electrochemical device according to claim 1, further comprising a diaphragm, the diaphragm comprising a porous substrate and a porous coating disposed on at least one surface of the porous substrate, wherein, The porous coating comprises inorganic particles and a binder.

9. The electrochemical device according to claim 8, wherein, The diaphragm satisfies at least one of the following: (a) The inorganic particles in the porous coating include at least one of magnesium hydroxide, boehmite, or aluminum oxide; (b) The binder in the porous coating comprises polyvinylidene fluoride; or (c) The thickness of the porous coating is T μm, where 1≤T≤5.

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

Images