Electrochemical device and electronic device

Abstract

An electrochemical device and an electronic device. The electrochemical device comprises an electrolyte, a positive electrode, a negative electrode and a separator, wherein the electrolyte comprises a first additive; the first additive is a mixed additive; and the mixed additive comprises the following additives at the following mass ratios: (1) a cyclic compound containing a carbonate group, LiBF4 and LiPO2F2 at a ratio of 1:0.01:0.01 to 1:20:30; and / or (2) a cyclic compound containing a sulfonic acid group, LiBF4 and LiPO2F2 at a ratio of 1:0.05:0.01 to 1:5:20. Based on the mass of the electrolyte, the mass percentage content of the mixed additive is x%, wherein 0.04≤x≤10.5. The positive electrode comprises a positive electrode current collector. The elongation at break of the positive electrode current collector is A%, the elongation at break of the separator is B%, and 5≤B / A≤150. The above configuration enables the electrochemical device to have an increased pass rate in nail penetration tests, and therefore the safety performance of the electrochemical device is improved.

Description

Electrochemical device and electronic device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 28, 2024, with application number 202410370489.5 and invention name “An electrochemical device and electronic device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of electrochemical technology, and in particular to an electrochemical device and an electronic device. Background Art

[0003] Lithium-ion batteries are widely used in automotive and consumer applications due to their high energy density, lack of memory effect, and high operating voltage. Currently, increasing the energy density of lithium-ion batteries requires continuously increasing their voltage. However, higher voltages result in higher electrode potentials for the positive electrode active material, making it more oxidizing, which can reduce the safety of lithium-ion batteries. Therefore, improving the safety of lithium-ion batteries has become a pressing issue. Summary of the Invention

[0004] The purpose of this application is to provide an electrochemical device and an electronic device to improve the safety performance of the electrochemical device. The specific technical solution is as follows:

[0005] The first aspect of the present application provides an electrochemical device comprising an electrolyte, a positive electrode, a negative electrode and a separator, wherein the electrolyte comprises a first additive, the first additive being a mixed additive, the mixed additive comprising additives in the following mass ratios: (1) a carbonate-containing cyclic compound: LiBF4:LiPO2F2=1:0.01:0.01 to 1:20:30, preferably, a carbonate-containing cyclic compound: LiBF4:LiPO2F2=1:0.1:0.1 to 1:10:20; and / or (2) a sulfonic acid-containing Cyclic compound: LiBF4:LiPO2F2=1:0.05:0.01 to 1:5:20, preferably, cyclic compound containing sulfonic acid group: LiBF4:LiPO2F2=1:0.1:0.05 to 1:2:10; based on the mass of the electrolyte, the mass percentage of the mixed additive is x%, 0.04≤x≤10.5; the positive electrode includes a positive electrode collector, wherein the elongation at break of the positive electrode collector is A%, the elongation at break of the isolation membrane is B%, 5≤B / A≤150, preferably, 10≤B / A≤90. By regulating the value of the ratio B / A of the elongation at break of the isolation membrane and the elongation at break of the positive electrode current collector within the scope of the present application, the electrochemical device can have better puncture resistance, and the penetration test pass rate of the electrochemical device can be improved, thereby improving the safety performance of the electrochemical device; by regulating the type, mass ratio and mass percentage of the compounds in the mixed additives within the scope of the present application, it is beneficial to the formation of ester, boron and phosphorus passivation layers at the positive and negative electrode interfaces of the electrochemical device, among which the ester organic passivation layer is beneficial to improving the cycle stability of the electrochemical device, and the boron and phosphorus inorganic passivation layers can reduce the probability of side reactions occurring during the puncture process of the electrochemical device, reduce heat generation, and further improve the puncture pass rate of the electrochemical device, thereby giving the electrochemical device good cycle performance while further improving the safety performance of the electrochemical device.

[0006] In some embodiments of the present application, based on the mass of the electrolyte, the mass percentage of the carbonate-containing cyclic compound is a%, the mass percentage of the sulfonic acid-containing cyclic compound is b%, the mass percentage of LiBF4 is c%, and the mass percentage of LiPO2F2 is d%, which satisfies at least one of the following characteristics: (1) 0.01≤a≤2; (2) 0.05≤b≤3.5; (3) 0.01≤c≤2; (4) 0.02≤d≤3. When the electrolyte satisfies at least one of (1) to (4), it is beneficial to improve the pass rate of the puncture test of the electrochemical device and further improve the safety performance of the electrochemical device.

[0007] In some embodiments of the present application, the carbonate-containing cyclic compound includes at least one of vinylene carbonate or fluoroethylene carbonate. The electrolyte containing the carbonate-containing cyclic compound within the scope of the present application can form an ester-based organic passivation layer at the interface between the positive and negative electrodes, which is beneficial for improving the cycling stability of the electrochemical device.

[0008] In some embodiments of the present application, the sulfonic acid group-containing cyclic compound includes at least one of 1,3-propane sultone, 2,4-butane sultone, or 1,4-butane sultone. The electrolyte containing the sulfonic acid group-containing cyclic compound within the scope of the present application can form an ester-based organic passivation layer at the interface between the positive and negative electrodes, which is beneficial for improving the cycling stability of the electrochemical device.

[0009] In some embodiments of the present application, the positive electrode current collector satisfies at least one of the following characteristics: (1) the positive electrode current collector includes aluminum; (2) the thickness of the positive electrode current collector is 5 μm to 20 μm; (3) the positive electrode current collector includes trace elements, the trace elements including at least one of silicon, copper, manganese, iron, zinc, magnesium, titanium, and vanadium, and the mass percentage of the trace elements is ≤ 2% based on the mass of the positive electrode current collector. When the positive electrode current collector satisfies at least one of (1) to (3), it is beneficial to improve the elongation at break of the positive electrode current collector and at the same time make the positive electrode current collector have better electron transport capability.

[0010] In some embodiments of the present application, 1.5 ≤ A ≤ 8, preferably 1.8 ≤ A ≤ 7.8. The elongation at break A% of the positive electrode current collector within the range of the present application can provide the electrochemical device with good puncture resistance, increase the pass rate of the electrochemical device's penetration test, and further improve the safety performance of the electrochemical device.

[0011] In some embodiments of the present application, 9≤B≤270, preferably 45≤B≤250. When the elongation at break B% of the separator is within the range of the present application, the electrochemical device can have good puncture resistance, increase the pass rate of the electrochemical device's penetration test, and further improve the safety performance of the electrochemical device.

[0012] In some embodiments of the present application, the isolation membrane includes a substrate and a coating disposed on at least one surface of the substrate, the coating including at least one of inorganic particles and / or polymers; the inorganic particles include at least one of silicon oxide, aluminum oxide, titanium oxide, zinc oxide, magnesium oxide, boehmite, magnesium hydroxide, calcium titanate, barium titanate, lithium phosphate, lithium titanium phosphate, or lithium lanthanum titanate; the polymer includes at least one of polymethyl methacrylate, polyvinylidene fluoride, polytetrafluoroethylene, a copolymer of vinylidene fluoride and hexafluoropropylene, polyhexafluoropropylene, or polyacrylonitrile. The isolation membrane includes a coating, the coating including at least one of the inorganic particles or polymers within the scope of the present application, the presence of the coating is conducive to isolating electrons, reducing the probability of side reactions, thereby reducing heat generation, reducing the risk of thermal runaway inside the electrochemical device, further improving the pass rate of the puncture test of the electrochemical device, and thus further improving the safety performance of the electrochemical device.

[0013] In some embodiments of the present application, the electrolyte further includes a second additive, which is a silicon-containing additive. The silicon-containing additive includes methyl orthosilicate, ethyl silicate, methyltrimethoxysilane, tetrapropoxysilane, isopropyl silicate, tetraallyl silicate, tetra(2-methoxyethoxy)silane, isopropyl silicate, butyl orthosilicate, tetra(isopropenyloxy)silane, allyltriethoxysilane, allyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, 1,2-bistrimethoxysilylethane, propyltrimethoxysilane, n-hexyltrimethoxysilane, butyltrimethoxysilane, 1,6-bis(triethoxysilyl)hexane, 1,6-bistrimethoxysilylhexane, 1,10-bis(trimethoxysilyl)octane, 6-ethyl-6-(2-methoxyethoxy)-2,5,7,10-tetraoxa-6 - at least one of silaundecane, trimethoxy(1,1,2-trimethylpropyl)-silane, bis(trimethoxysilylmethyl)ethylene, (3,3-dimethylbutyl)triethoxysilane, 3-butenetriethoxysilane, allyltriacetoxysilane, 1-(triethoxysilyl)-2-pentene, 10-alkenylundecanyltrimethoxysilane, diallyldiethoxysilane, 2-butenyltriethoxysilane, cyclopentanetrimethoxysilane, 11-cyanoundecyltrimethoxysilane, hexadecyltriethoxysilane, cyanohexyltrimethoxysilane, isobutyltriethoxysilane, isobutyltrimethoxysilane, tert-butyltrimethoxysilane or 3-cyanopropyltrimethoxysilane; based on the mass of the electrolyte, the mass percentage of the silicon-containing additive is e%, 0.04≤e≤3.0, preferably 0.1≤e≤1.2. The electrolyte includes silicon-containing additives within the scope of this application and regulates the mass percentage of the silicon-containing additives within the scope of this application, which is conducive to the formation of a silicon-containing inorganic passivation layer at the negative electrode interface, reducing the probability of side reactions, reducing heat generation, and further improving the pass rate of the electrochemical device puncture test, thereby further improving the safety performance of the electrochemical device.

[0014] The second aspect of the present application provides an electronic device comprising the electrochemical device provided in the first aspect of the present application. The electrochemical device provided in the first aspect of the present application has good safety performance, and thus the electronic device provided in the second aspect of the present application has good safety performance.

[0015] Beneficial effects of this application:

[0016] The present application provides an electrochemical device and an electronic device, the electrochemical device comprising an electrolyte, a positive electrode, a negative electrode and an isolation membrane, wherein the electrolyte comprises a first additive, the first additive being a mixed additive, the mixed additive comprising additives in the following mass ratios: (1) a carbonate-containing cyclic compound: LiBF4:LiPO2F2=1:0.01:0.01 to 1:20:30; and / or (2) a sulfonic acid-containing cyclic compound: LiBF4:LiPO2F2=1:0.05:0.01 to 1:5:20; based on the mass of the electrolyte, the mass percentage of the mixed additive is x%, 0.04≤x≤10.5; the positive electrode comprises a positive electrode current collector, wherein the elongation at break of the positive electrode current collector is A%, and the elongation at break of the isolation membrane is B%, 5≤B / A≤150. By regulating the value of the ratio B / A of the elongation at break of the isolation membrane and the elongation at break of the positive electrode current collector within the scope of the present application, the electrochemical device can have better puncture resistance, and the penetration test pass rate of the electrochemical device can be improved, thereby improving the safety performance of the electrochemical device; by regulating the type, mass ratio and mass percentage of the compounds in the mixed additives within the scope of the present application, it is beneficial to the formation of ester, boron and phosphorus passivation layers at the positive and negative electrode interfaces of the electrochemical device, among which the ester organic passivation layer is beneficial to improving the cycle stability of the electrochemical device, and the boron and phosphorus inorganic passivation layers can reduce the probability of side reactions occurring during the puncture process of the electrochemical device, reduce heat generation, and further improve the puncture pass rate of the electrochemical device, thereby giving the electrochemical device good cycle performance while further improving the safety performance of the electrochemical device.

[0017] Of course, it is not necessary to achieve all the advantages described above at the same time when implementing any product or method of the present application. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. 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.

[0019] It should be noted that, in the specific embodiments of the present application, a lithium-ion battery is used as an example of an electrochemical device to explain the present application, but the electrochemical device of the present application is not limited to a lithium-ion battery.

[0020] A first aspect of the present application provides an electrochemical device comprising an electrolyte, a positive electrode, a negative electrode and a separator, wherein the electrolyte comprises a first additive, the first additive being a mixed additive, the mixed additive comprising additives in the following mass ratios: (1) a carbonate-containing cyclic compound: LiBF4:LiPO2F2=1:0.01:0.01 to 1:20:30, preferably, a carbonate-containing cyclic compound: LiBF4:LiPO2F2=1:0.1:0.1 to 1:10:20; and / or (2) a sulfonic acid-containing cyclic compound: LiBF4:LiPO2F2=1:0.05:0.01 to 1:5:20, preferably, a sulfonic acid-containing cyclic compound: LiBF4:LiPO2F2=1:0.05:0.01 to 1:5:20. :0.1:0.05 to 1:2:10; based on the mass of the electrolyte, the mass percentage of the mixed additive is x%, 0.04≤x≤10.5, for example, the value of x% can be 0.04%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 8.4%, 9%, 10%, 10.5%, or a range consisting of any two values ​​therein; the positive electrode includes a positive current collector, wherein the elongation at break of the positive current collector is A%, and the elongation at break of the separator is B%, 5≤B / A≤150, preferably 10≤B / A≤90, for example, the value of B / A can be 5, 10, 30, 50, 80, 90, 100, 130, 150, or a range consisting of any two values ​​therein. It should be noted that the positive current collector and separator substrate were purchased from commercial products, and their elongation at break was tested after purchase.

[0021] The inventors have found that by regulating the ratio of the elongation at break of the isolation membrane to the elongation at break of the positive electrode current collector (B / A) within the scope of the present application, the puncture test pass rate of the electrochemical device can be improved, thereby improving the safety performance of the electrochemical device; by regulating the types, mass ratios and mass percentages of the compounds in the mixed additives within the scope of the present application, it is beneficial to the formation of ester, boron and phosphorus passivation layers at the positive and negative electrode interfaces of the electrochemical device, among which the ester organic passivation layer is beneficial to improving the cycle stability of the electrochemical device, and the boron and phosphorus inorganic passivation layers can reduce the probability of side reactions occurring during the puncture process of the electrochemical device, reduce heat generation, and further improve the puncture pass rate of the electrochemical device, thereby enabling the electrochemical device to have good cycle performance while further improving the safety performance of the electrochemical device.

[0022] In some embodiments of the present application, the mass percentage of the carbonate-containing cyclic compound is a%, based on the mass of the electrolyte, and 0.01≤a≤2. For example, the mass percentage a% of the carbonate-containing cyclic compound can be 0.01%, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, or a range consisting of any two of these values. By regulating the mass percentage a% of the carbonate-containing cyclic compound within the scope of the present application, an ester organic passivation layer can be formed at the interface between the positive electrode and the negative electrode, which is beneficial to improving the cycle stability of the electrochemical device.

[0023] In some embodiments of the present application, based on the mass of the electrolyte, the mass percentage of the cyclic compound containing a sulfonic acid group is b%, and 0.05≤b≤3.5. For example, the mass percentage of the cyclic compound containing a sulfonic acid group b% can be 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, or a range consisting of any two of these values. By regulating the mass percentage of the cyclic compound containing a sulfonic acid group b% within the scope of the present application, an ester organic passivation layer can be formed at the interface between the positive electrode and the negative electrode, which is beneficial to improving the cycle stability of the electrochemical device.

[0024] In some embodiments of the present application, based on the mass of the electrolyte, the mass percentage of LiBF4 is c%, 0.01≤c≤2. The value of the mass percentage c% of LiBF4 can be 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.5%, 2% or a range consisting of any two values ​​therein. By regulating the value of the mass percentage c% of LiBF4 within the scope of the present application, it is beneficial to form a boron-based inorganic passivation layer at the interface of the positive and negative electrodes, reduce the probability of side reactions occurring during the puncture process of the electrochemical device, reduce the generation of heat, further improve the puncture pass rate of the electrochemical device, and thus further improve the safety performance of the electrochemical device.

[0025] In some embodiments of the present application, based on the mass of the electrolyte, the mass percentage of LiPO2F2 is d%, 0.02≤d≤3. For example, the mass percentage of LiPO2F2 d% can be 0.02%, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3% or a range consisting of any two values ​​therein. By regulating the value of the mass percentage of LiPO2F2 d% within the scope of the present application, it is beneficial to form a phosphorus-based inorganic passivation layer at the interface of the positive and negative electrodes, reduce the probability of side reactions occurring during the puncture of the electrochemical device, reduce heat generation, further improve the puncture pass rate of the electrochemical device, and thus further improve the safety performance of the electrochemical device.

[0026] In some embodiments of the present application, the carbonate-containing cyclic compound includes at least one of vinylene carbonate (VC) or fluoroethylene carbonate (FEC). The electrolyte including the carbonate-containing cyclic compound within the scope of the present application can form an ester-based organic passivation layer at the interface between the positive and negative electrodes, which is beneficial for improving the cycling stability of the electrochemical device.

[0027] In some embodiments of the present application, the sulfonic acid group-containing cyclic compound includes at least one of 1,3-propane sultone, 2,4-butane sultone, or 1,4-butane sultone. The electrolyte containing the sulfonic acid group-containing cyclic compound within the scope of the present application can form an ester-based organic passivation layer at the interface between the positive and negative electrodes, which is beneficial for improving the cycling stability of the electrochemical device.

[0028] In some embodiments of the present application, the positive electrode current collector includes aluminum. The aluminum-containing positive electrode current collector may include aluminum foil, aluminum alloy foil, aluminum-carbon composite current collector, etc. The inclusion of aluminum in the positive electrode current collector facilitates the formation of an aluminum oxide passivation layer on the surface of the positive electrode current collector, thereby inhibiting corrosion of the positive electrode current collector.

[0029] In some embodiments of the present application, the thickness of the positive electrode current collector is 5 μm to 20 μm. For example, the thickness of the positive electrode current collector can be 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, or a range consisting of any two of these values.

[0030] In some embodiments of the present application, the positive electrode current collector includes trace elements, and the trace elements include at least one of silicon, copper, manganese, iron, zinc, magnesium, titanium, and vanadium. The mass percentage of the trace elements is ≤ 2% based on the mass of the positive electrode current collector. For example, the mass percentage of the trace elements can be 0.001%, 0.01%, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, or a range consisting of any two of these values. The inclusion of trace elements within the scope of the present application in the positive electrode current collector is beneficial to improving the elongation at break or the conductivity of the positive electrode current collector.

[0031] In some embodiments of the present application, 1.5≤A≤8, preferably 1.8≤A≤7.8. For example, the elongation at break A% of the positive electrode current collector can be 1.5%, 1.8%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.8%, 8%, or a range consisting of any two of these values. The elongation at break A% of the positive electrode current collector within the range of the present application can improve the pass rate of the penetration test of the electrochemical device and further improve the safety performance of the electrochemical device.

[0032] In some embodiments of the present application, 9≤B≤270, preferably 45≤B≤250. For example, the elongation at break B% of the separator can be 9%, 15%, 30%, 40%, 45%, 80%, 100%, 130%, 150%, 180%, 200%, 230%, 250%, 260%, 270%, or a range consisting of any two of these values. When the elongation at break B% of the separator is within the range of the present application, the pass rate of the penetration test of the electrochemical device can be increased, thereby further improving the safety performance of the electrochemical device.

[0033] In some embodiments of the present application, the isolation membrane material may include, but is not limited to, at least one of polyethylene (PE), polypropylene (PP)-based polyolefins (PO), polyesters (e.g., polyethylene terephthalate (PET) film), cellulose, polyimide (PI), polyamide (PA), spandex, or aramid. The type of isolation membrane may include at least one of a woven membrane, a non-woven membrane, a microporous membrane, a composite membrane, a rolled membrane, or a spun membrane. The thickness of the isolation membrane may be 3 μm to 30 μm. The porosity of the isolation membrane may be 20% to 65%.

[0034] In some embodiments of the present application, the isolation membrane includes a substrate and a coating disposed on at least one surface of the substrate, the coating including at least one of inorganic particles and / or polymers; the inorganic particles include at least one of silicon oxide, aluminum oxide, titanium oxide, zinc oxide, magnesium oxide, boehmite, magnesium hydroxide, calcium titanate, barium titanate, lithium phosphate, lithium titanium phosphate, or lithium lanthanum titanate; the polymer includes at least one of polymethyl methacrylate, polyvinylidene fluoride, polytetrafluoroethylene, a copolymer of vinylidene fluoride and hexafluoropropylene, polyhexafluoropropylene, or polyacrylonitrile. The coating may also include a thickener and a wetting agent. The present application does not particularly limit the types of thickeners and wetting agents, as long as they can achieve the purpose of the present application. For example, the thickener may include but is not limited to at least one of sodium carboxymethyl cellulose or lithium carboxymethyl cellulose; the wetting agent may include but is not limited to at least one of dimethylsiloxane, sodium lauryl sulfate, trialkyl phosphate, methyl decanoate, or lauryl acetate. The isolation membrane includes a coating, which includes at least one of the inorganic particles and / or polymers within the scope of this application. The presence of the coating is beneficial to isolating electrons, reducing the probability of side reactions, thereby reducing heat generation, reducing the risk of thermal runaway inside the electrochemical device, and further improving the puncture test pass rate of the electrochemical device, thereby further improving the safety performance of the electrochemical device.

[0035] In some embodiments of the present application, the electrolyte further includes a second additive, which is a silicon-containing additive. The silicon-containing additive includes methyl orthosilicate, ethyl silicate, methyltrimethoxysilane, tetrapropoxysilane, isopropyl silicate, tetraallyl silicate, tetra(2-methoxyethoxy)silane, isopropyl silicate, butyl orthosilicate, tetra(isopropenyloxy)silane, allyltriethoxysilane, allyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, 1,2-bistrimethoxysilylethane, propyltrimethoxysilane, n-hexyltrimethoxysilane, butyltrimethoxysilane, 1,6-bis(triethoxysilyl)hexane, 1,6-bistrimethoxysilylhexane, 1,10-bis(trimethoxysilyl)octane, 6-ethyl-6-(2-methoxyethoxy)-2,5,7,10-tetraoxa-6 - at least one of silaundecane, trimethoxy(1,1,2-trimethylpropyl)-silane, bis(trimethoxysilylmethyl)ethylene, (3,3-dimethylbutyl)triethoxysilane, 3-butenetriethoxysilane, allyltriacetoxysilane, 1-(triethoxysilyl)-2-pentene, 10-alkenylundecanyltrimethoxysilane, diallyldiethoxysilane, 2-butenyltriethoxysilane, cyclopentanetrimethoxysilane, 11-cyanoundecyltrimethoxysilane, hexadecyltriethoxysilane, cyanohexyltrimethoxysilane, isobutyltriethoxysilane, isobutyltrimethoxysilane, tert-butyltrimethoxysilane or 3-cyanopropyltrimethoxysilane; based on the mass of the electrolyte, the mass percentage of the silicon-containing additive is e%, 0.04≤e≤3.0, preferably 0.1≤e≤1.2. For example, the mass percentage e% of the silicon-containing additive can be 0.04%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.3%, 1.5%, 1.8%, 2.0%, 2.3%, 2.5%, 2.8%, 3%, or a range consisting of any two of these values. The electrolyte includes the silicon-containing additive within the scope of this application and regulates the mass percentage of the silicon-containing additive within the scope of this application, which is conducive to forming a silicon-containing inorganic passivation layer at the negative electrode interface, reducing the probability of side reactions, reducing heat generation, and further improving the puncture pass rate of the electrochemical device, thereby further improving the safety performance of the electrochemical device.

[0036] The electrolyte of the present application includes a lithium salt and a non-aqueous organic solvent. The present application has no particular restrictions on the lithium salt, as long as the purpose of the present application can be achieved. For example, the lithium salt may include but is not limited to at least one of LiPF6, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, Li2SiF6, lithium bis(oxalatoborate) (LiBOB) or lithium difluoroborate. The present application has no particular restrictions on the content of the lithium salt in the electrolyte, as long as the purpose of the present application can be achieved. For example, based on the mass of the electrolyte, the mass percentage of the lithium salt is 8% to 15%. The present application has no particular restrictions on the type of the above-mentioned non-aqueous organic solvent, as long as the purpose of the present application can be achieved, for example, it may include but is not limited to at least one of a carbonate compound, a carboxylate compound, an ether compound or other organic solvents. The above-mentioned carbonate compound may include but is not limited to at least one of a chain carbonate compound or a cyclic carbonate compound. The above-mentioned linear carbonate compound may include but is not limited to at least one of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate or methylethyl carbonate. The above-mentioned cyclic carbonate compound may include but is not limited to at least one of ethylene carbonate, propylene carbonate, butylene carbonate or vinylethylene carbonate. The above-mentioned carboxylate compound may include but is not limited to at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanoic acid, valerolactone or caprolactone. The above-mentioned ether compound may include but is not limited to at least one of ethylene glycol dimethyl ether, 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 may include but are not limited to at least one of dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate or trioctyl phosphate.

[0037] The positive electrode sheet of the present application includes a positive electrode current collector and a positive electrode material layer provided on at least one surface of the positive electrode current collector. In the present application, the positive electrode material layer can be provided 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. This application is not particularly limited, as long as the purpose of this application can be achieved. The positive electrode material layer of the present application includes a positive electrode active material. This application does not particularly limit the type of positive electrode active material, as long as the purpose of this application can be achieved. For example, the positive electrode active material can include but is not limited to lithium nickel cobalt manganese oxide (such as NCM811, NCM622, NCM523, NCM111), lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based material, lithium cobalt oxide (LiCoO2), lithium manganese oxide, lithium iron manganese phosphate or lithium titanate. In the present application, there is no particular limitation on the thickness of the positive electrode material layer, as long as the purpose of this application can be achieved. For example, the thickness of the single-sided positive electrode material layer is 30μm to 120μm. The positive electrode material layer of the present application may also include a conductive agent and a binder. The present application has no particular restrictions on the conductive agent and the binder, as long as the purpose of the present application can be achieved. For example, the conductive agent may include but is not limited to at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fibers, flake graphite, graphene, metal materials or conductive polymers, and the conductive carbon black may include but is not limited to at least one of acetylene black or Ketjen black. The above-mentioned carbon nanotubes may include but are not limited to single-walled carbon nanotubes and / or multi-walled carbon nanotubes. The above-mentioned carbon fibers may include but are not limited to vapor-grown carbon fibers (VGCF) and / or nano-carbon fibers. The above-mentioned metal materials may include but are not limited to metal powder and / or metal fibers. Specifically, the metal may include but is not limited to at least one of copper, nickel, aluminum or silver. The above-mentioned conductive polymers may include but are not limited to at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene or polypyrrole. For example, the binder may include, but is not limited to, at least one of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyvinyl alcohol, carboxymethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, polyimide, polyamide-imide, styrene-butadiene rubber, or polyvinylidene fluoride. The present application does not particularly limit the mass ratio of the positive electrode active material, conductive agent, and binder in the positive electrode material layer. Those skilled in the art may select the binder according to actual needs, as long as the purpose of the present application can be achieved.

[0038] This application places no particular restrictions on the negative electrode sheet, as long as the purpose of this application can be achieved. For example, the negative electrode sheet includes a negative electrode current collector and a negative electrode material layer provided on at least one surface of the negative electrode current collector. In this application, the negative electrode material layer can be provided on one surface in the thickness direction of the negative electrode current collector, or can be provided on both surfaces in the thickness direction of the negative electrode current collector. It should be noted that the "surface" here can be the entire area of the negative electrode current collector or a partial area of the negative electrode current collector. This application places no particular restrictions, as long as the purpose of this application can be achieved. This application places no particular restrictions on the negative electrode current collector, as long as the purpose of this application can be achieved. For example, the negative electrode current collector can include, but is not limited to, copper foil, copper alloy foil, nickel foil, titanium foil, nickel foam, copper foam, or composite current collector, etc. The negative electrode material layer of this application includes negative electrode active materials. This application places no particular restrictions on the types of negative electrode active materials, as long as the purpose of this application can be achieved. For example, the negative electrode active materials can include, but are not limited to, natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO x (0 < x ≤ 2), or metallic lithium, etc., at least one of which. In this application, there are no particular restrictions on the thicknesses of the negative electrode current collector and the negative electrode active material layer, as long as the purpose of this application can be achieved. For example, the thickness of the negative electrode current collector is 4 μm to 15 μm, and the thickness of the single-sided negative electrode active material layer is 30 μm to 130 μm. The negative electrode active material layer of this application can also include a conductive agent, a binder, and a thickening agent. This application places no particular restrictions on the types of the conductive agent, the binder, and the thickening agent, as long as the purpose of this application can be achieved. For example, the conductive agent and the binder can be at least one of the above-mentioned conductive agents and the above-mentioned binders. The thickening agent can include, but is not limited to, at least one of sodium carboxymethyl cellulose or lithium carboxymethyl cellulose. This application places no particular restrictions on the mass ratio of the negative electrode active material, the conductive agent, the binder, and the thickening agent in the negative electrode material layer. Those skilled in the art can select according to actual needs, as long as the purpose of this application can be achieved can be achieved.

[0039] The electrochemical device of this application further includes a housing for accommodating the positive electrode sheet, the separator, the negative electrode sheet, and the electrolyte, as well as other components known in the field of electrochemistry. This application places no limitations on the above-mentioned other components. This application places no particular restrictions on the housing, which can be a housing well-known in the art, as long as the purpose of this application can be achieved. For example, the housing can be a hard-shell housing or a flexible housing. The material of the hard-shell housing can be metal. This application places no limitations on the type of metal, and a known metal hard-shell housing in the art can be used, as long as the purpose of this application can be achieved. The flexible housing can be a metal plastic film, such as an aluminum plastic film, a steel plastic film, etc.

[0040] The electrochemical device of the present application is not particularly limited and may include any device that undergoes an electrochemical reaction. In one embodiment of the present application, the electrochemical device may 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.

[0041] The preparation process of the electrochemical device of the present application is well known to those skilled in the art and is not particularly limited in the present application. For example, it may 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 and other operations as needed to obtain an electrode assembly with a wound structure, placing the electrode assembly in a packaging bag, injecting an electrolyte into the packaging bag and sealing it to obtain an electrochemical device; or stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and then fixing the four corners of the entire stacked structure with tape to obtain an electrode assembly with a stacked structure, placing the electrode assembly in a packaging bag, injecting an electrolyte into the packaging bag and sealing it to obtain an electrochemical device. In addition, an overcurrent protection element, a guide plate, etc. may also be placed in the packaging bag as needed to prevent pressure rise and overcharging and discharging inside the electrochemical device.

[0042] The second aspect of the present application provides an electronic device comprising the electrochemical device provided in the first aspect of the present application. The electrochemical device provided in the first aspect of the present application has good safety performance, and thus the electronic device provided in the second aspect of the present application has good safety performance.

[0043] The electronic device of the present application is not particularly limited and can be any electronic device known in the art. In some embodiments, the electronic device can include, but is not limited to, a laptop computer, a pen-type computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a headset, a video recorder, an LCD television, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, a power tool, a flashlight, a camera, a large household battery or a lithium-ion capacitor, etc.

[0044] Example

[0045] The following examples and comparative examples are provided to more specifically illustrate the embodiments of the present invention. Various tests and evaluations were performed according to the following methods. In addition, unless otherwise specified, "parts" and "%" are based on mass.

[0046] Test methods and equipment:

[0047] Cathode current collector and separator elongation test

[0048] A tensile testing machine (model: JHY-5000) was used for the test. The test sample length was 200±0.5mm, the width was 15±0.25mm, the tensile speed was set to 50mm / min, the chuck distance of the testing machine was 125±0.1mm, 5 parallel samples were tested, and the average value was taken as the test result. During the test, the length direction of the sample was parallel to the axis of the fixture, and the sample was kept straight. The experimental temperature was 20±5℃; elongation at break = stretched length / original length.

[0049] Lithium-ion battery puncture test

[0050] At 25°C, charge the lithium-ion battery at 0.5C to 4.45V, then charge it at 4.45V to 0.02C. Place the battery on a test bench at 20±5°C. Use a 4mm diameter steel nail at a speed of 20mm / s to completely pierce the battery from the center. If there is no fire or explosion, it is considered a successful puncture. 20 batteries are tested in each group.

[0051] Puncture test pass rate = number of lithium-ion batteries that passed the puncture test / 20. The higher the puncture test pass rate, the better the safety performance of the lithium-ion battery.

[0052] Example 1-1

[0053] <Preparation of Electrolyte>

[0054] In an argon atmosphere glove box with a water content of less than 10 ppm, ethylene carbonate and ethyl methyl carbonate were mixed in a mass ratio of 3:7 to obtain a non-aqueous organic solvent, and then lithium salt lithium hexafluorophosphate (LiPF6) and mixed additives (fluoroethylene carbonate, LiBF 4、 LiPO2F2 is mixed in a mass ratio of 1:0.01:0.01 to obtain an electrolyte. The electrolyte comprises 12.5% ​​by mass of lithium hexafluorophosphate, 2.04% by mass of the mixed additive, and the balance being a non-aqueous organic solvent.

[0055] <Preparation of Separator>

[0056] A polyethylene (PE) film (provided by Celgard) with a thickness of 10 μm was used as the separator, wherein the elongation at break of the separator was 45%.

[0057] <Preparation of positive electrode sheet>

[0058] The positive electrode active material is lithium nickel cobalt manganese oxide LiNi 0.8 Co 0.1 Mn 0.1O2 (NCM811), positive electrode binder polyvinylidene fluoride (PVDF), and conductive agent conductive carbon black (Super P) are mixed in a mass ratio of 96:2:2, N-methylpyrrolidone (NMP) is added, and the mixture is stirred evenly under the action of a vacuum mixer to obtain a positive electrode slurry with a solid content of 70wt%. The positive electrode slurry is evenly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 14μm, and baked at 120°C for 1 hour to obtain a positive electrode sheet with a single-sided positive electrode material layer coated with a coating thickness of 110μm. Repeat the above steps on the other surface of the positive electrode current collector aluminum foil to obtain a positive electrode sheet with a double-sided positive electrode material layer coated. Then, after drying under vacuum conditions at 120°C for 1 hour, a positive electrode sheet with a specification of 74mm×867mm is obtained by cold pressing, cutting, and slitting. Among them, the compaction density of the positive electrode material layer is 3.4g / cm 3 , the elongation at break of the positive electrode current collector is 1.8%.

[0059] <Preparation of negative electrode sheet>

[0060] The negative electrode active material artificial graphite, sodium carboxymethyl cellulose (CMC), and the negative electrode binder styrene-butadiene rubber are mixed in a mass ratio of 96:2:2, deionized water is added, and the mixture is stirred evenly under the action of a vacuum mixer to obtain a negative electrode slurry with a solid content of 65wt%. The negative electrode slurry is evenly coated on one surface of a negative electrode current collector copper foil with a thickness of 12μm, and baked at 120°C for 1 hour to obtain a negative electrode sheet with a single-sided coating of a negative electrode material layer with a coating thickness of 100μm. The above steps are repeated on the other surface of the negative electrode current collector copper foil to obtain a negative electrode sheet with a double-sided coating of a negative electrode material layer. Then, after drying under vacuum conditions at 120°C for 1 hour, a negative electrode sheet with a specification of 76mm×875mm is obtained by cold pressing, cutting, and slitting. Among them, the compaction density of the negative electrode material layer is 1.6g / cm 3 .

[0061] <Preparation of lithium-ion batteries>

[0062] The positive electrode sheet, separator, and negative electrode sheet prepared above are stacked in order, with the separator positioned between the positive and negative electrodes to provide insulation, and then wound to form an electrode assembly. The electrode assembly is placed in an aluminum-plastic film packaging bag, dehydrated at 80°C, and then injected with the electrolyte prepared above. The lithium-ion battery is produced through vacuum packaging, standing, forming, degassing, and trimming. The upper limit of the formation voltage is 4.15V, the formation temperature is 70°C, and the formation standing time is 2 hours.

[0063] Example 1-2 to Example 1-7

[0064] Except that the mass ratio of the carbonate-containing cyclic compound, LiBF4, and LiPO2F2 in the mixed additives and the mass percentage of the mixed additives are adjusted as shown in Table 1 in <Preparation of Electrolyte>, and the mass percentage of the non-aqueous organic solvent is changed accordingly, the rest is the same as Example 1-1.

[0065] Example 1-8 to Example 1-13

[0066] Except for adjusting the elongation at break of the separator as shown in Table 1, the other procedures were the same as those in Example 1-2.

[0067] Example 1-14 to Example 1-21

[0068] The following procedures were the same as those in Example 1-2, except that the elongation at break of the positive electrode current collector was adjusted as shown in Table 1; and the elongation at break of the separator was adjusted as shown in Table 1.

[0069] Examples 1-22

[0070] Except that the type of the carbonate-containing cyclic compound in the mixed additive was adjusted as shown in Table 1 in the <Preparation of Electrolyte>, the rest was the same as in Example 1-20.

[0071] Example 1-23 to Example 1-29

[0072] Except that the mass ratio of the sulfonic acid group-containing cyclic compound, LiBF4, and LiPO2F2 in the mixed additive and the mass percentage of the mixed additive are adjusted as shown in Table 1 in <Preparation of Electrolyte>, the mass percentage of the non-aqueous organic solvent is changed accordingly, and the carbonate group-containing cyclic compound is not added to the electrolyte, the rest is the same as Example 1-1.

[0073] Example 1-30 to Example 1-32

[0074] Except for adjusting the mass ratio of the carbonate-containing cyclic compound, LiBF4, and LiPO2F2 and the mass ratio of the sulfonic acid-containing cyclic compound, LiBF4, and LiPO2F2 in the mixed additives as shown in Table 1 in <Preparation of Electrolyte>, the mass percentage of the non-aqueous organic solvent is changed accordingly, and the rest is the same as Example 1-1.

[0075] Example 2-1

[0076] <Preparation of Separator>

[0077] The inorganic particles of aluminum oxide, the thickener sodium carboxymethyl cellulose and the wetting agent dimethylsiloxane were mixed in a mass ratio of 95:0.5:4.5, deionized water was added, and the mixture was stirred evenly under the action of a vacuum mixer to obtain a porous coating slurry with a viscosity of 40mPa·s and a solid content of 5%. The porous coating slurry was evenly coated on one surface of a polyethylene porous substrate with a thickness of 10μm, and dried in an oven at 85°C for 4h to obtain a single-sided porous coating isolation membrane with a thickness of 2μm. The porous coating slurry was evenly coated on the other surface of the polyethylene porous substrate and dried in an oven at 85°C for 4h to obtain a double-sided porous coating isolation membrane.

[0078] Except that the isolation film was prepared according to the above steps, the rest was the same as in Example 1-11.

[0079] Example 2-2, Example 2-3

[0080] Except that the types of inorganic particles were adjusted as shown in Table 2, the rest of the process was the same as in Example 2-1.

[0081] Examples 2-4

[0082] <Preparation of Separator>

[0083] The polymer polymethyl methacrylate, the thickener sodium carboxymethyl cellulose and the wetting agent dimethylsiloxane were mixed in a mass ratio of 95:0.5:4.5, deionized water was added, and the mixture was stirred evenly under the action of a vacuum mixer to obtain a porous coating slurry with a viscosity of 50mPa·s and a solid content of 5%. The porous coating slurry was evenly coated on one surface of a polyethylene porous substrate with a thickness of 10μm, and dried in an oven at 85°C for 4h to obtain an isolation membrane with a single-sided porous coating. The thickness of the single-sided porous coating was 2μm. The porous coating slurry was evenly coated on the other surface of the polyethylene porous substrate, and dried in an oven at 85°C for 4h to obtain an isolation membrane with a double-sided porous coating.

[0084] Except that the isolation film was prepared according to the above steps, the rest was the same as in Example 1-11.

[0085] Examples 2-5

[0086] Except that the type of polymer was adjusted as shown in Table 2 in the "Preparation of Separator", the rest was the same as in Example 2-4.

[0087] Example 3-1 to Example 3-11

[0088] Except that the type and mass percentage of the silicon-containing additives in the preparation of the electrolyte were adjusted as shown in Table 3, and the mass percentage of the non-aqueous organic solvent was changed accordingly, the rest was the same as in Example 2-1.

[0089] Example 3-12, Example 3-13

[0090] Except that the type and mass percentage of the silicon-containing additives in the preparation of the electrolyte were adjusted as shown in Table 3, and the mass percentage of the non-aqueous organic solvent was changed accordingly, the rest was the same as in Examples 1-11.

[0091] Comparative Example 1

[0092] Except for the fact that no mixed additives were added in the preparation of the electrolyte and the mass percentage of the non-aqueous organic solvent was changed, the rest was the same as in Example 1-1.

[0093] Comparative Example 2, Comparative Example 3

[0094] In addition to adjusting the carbonate-containing cyclic compound and LiBF in the mixed additives as shown in Table 1, the electrolyte solution was prepared. 4、 Except for the changes in the mass ratio of LiPO2F2, the mass percentage of the mixed additives, and the mass percentage of the non-aqueous organic solvent, the rest is the same as Example 1-1.

[0095] Comparative Example 4

[0096] The same procedures as in Example 1-1 were followed except that the elongation at break of the positive electrode current collector was adjusted as shown in Table 1 in the preparation of the positive electrode sheet and the elongation at break of the separator was adjusted as shown in Table 1 in the preparation of the separator.

[0097] Comparative Example 5

[0098] The same procedures as in Example 1-2 were used except that the elongation at break of the positive electrode current collector was adjusted as shown in Table 1 in the preparation of the positive electrode sheet and the elongation at break of the separator was adjusted as shown in Table 1 in the preparation of the separator.

[0099] Comparative Example 6, Comparative Example 7

[0100] In addition to adjusting the sulfonic acid group-containing cyclic compound and LiBF in the mixed additives as shown in Table 1, the electrolyte solution was prepared. 4、 The mass ratio of LiPO2F2 and the mass percentage of the mixed additives, and the mass percentage of the non-aqueous organic solvent are changed accordingly. Except that the carbonate-containing cyclic compound is not added to the electrolyte, the rest is the same as Example 1-1.

[0101] The preparation parameters and performance parameters of each embodiment and comparative example are shown in Tables 1 to 3.

[0102] It can be seen from Examples 1-1 to 1-32 and Comparative Examples 1 to 7 that the lithium-ion battery electrolytes of each embodiment of the present application include mixed additives within the scope of the present application, and the mass ratio of each compound in the mixed additive, the mass percentage x% of the mixed additive, and the ratio B / A of the elongation at break of the isolation membrane and the elongation at break of the positive electrode current collector are regulated within the scope of the present application, while the lithium-ion batteries in the comparative examples do not meet the above characteristics at the same time. The lithium-ion batteries in each embodiment have a higher puncture test pass rate, indicating that the safety performance of the lithium-ion battery is improved.

[0103] The mass ratio of the carbonate-containing cyclic compound, LiBF4, and LiPO2F2 in a mixed additive typically affects the safety performance of lithium-ion batteries. As shown in Examples 1-1 to 1-7 and Comparative Examples 1 to 3, by adjusting the mass ratio of the carbonate-containing cyclic compound, LiBF4, and LiPO2F2 within the range of this application, lithium-ion batteries achieve a higher puncture test pass rate, demonstrating improved safety performance.

[0104] The mass ratio of the sulfonic acid group-containing cyclic compound, LiBF4, and LiPO2F2 in a mixed additive typically affects the safety performance of lithium-ion batteries. As shown in Examples 1-23 to 1-27, Comparative Examples 1, 6, and 7, by adjusting the mass ratio of the sulfonic acid group-containing cyclic compound, LiBF4, and LiPO2F2 within the range of this application, lithium-ion batteries achieve a higher puncture test pass rate, demonstrating improved safety performance.

[0105] The weight percentage of a mixed additive (x%), a carbonate-containing cyclic compound (a%), a sulfonic acid-containing cyclic compound (b%), LiBF4 (c%), and LiPO2F2 (d%) generally affects the safety performance of lithium-ion batteries. As can be seen from Examples 1 to 32, by adjusting the values ​​of x%, a%, b%, and d% within the ranges of this application, lithium-ion batteries achieve a higher puncture test pass rate, indicating improved safety performance.

[0106] The ratio (B / A) of the separator's elongation at break to the positive electrode current collector's elongation at break generally affects the safety performance of lithium-ion batteries. As can be seen from Examples 1-2, 1-8, 1-21, Comparative Examples 4, and 5, by adjusting the B / A value within the range of this application, the lithium-ion battery achieves a higher puncture test pass rate, indicating improved lithium-ion battery safety.

[0107] The positive electrode current collector elongation at break (A%) typically affects the safety performance of lithium-ion batteries. As can be seen from Examples 1-2, 1-14, and 1-17, by adjusting the value of A% within the range of this application, lithium-ion batteries achieve a higher puncture test pass rate, indicating further improved safety performance.

[0108] The elongation at break (B%) of the positive electrode current collector typically affects the safety performance of lithium-ion batteries. As can be seen from Examples 1-2, 1-8 to 1-13, and 1-18 to 1-21, by adjusting the B% value within the range of this application, the lithium-ion batteries achieved a higher puncture test pass rate, indicating that the safety performance of the lithium-ion batteries has been further improved.

[0109] The type of carbonate-containing cyclic compound generally affects the safety performance of lithium-ion batteries. As can be seen from Examples 1-20 and 1-22, lithium-ion batteries containing carbonate-containing cyclic compounds within the scope of this application exhibit higher puncture test pass rates, demonstrating further improved safety performance.

[0110] The type of sulfonic acid group-containing cyclic compound generally affects the safety performance of lithium-ion batteries. As can be seen from Examples 1-25, 1-28, and 1-29, lithium-ion batteries containing a sulfonic acid group-containing cyclic compound within the scope of this application exhibit a higher puncture test pass rate, indicating that the safety performance of lithium-ion batteries is further improved.

[0111] Table 2 Note: “ / ” in Table 2 indicates no relevant parameters.

[0112] It can be seen from Examples 1-11 and 2-1 to 2-5 that the isolation membrane further includes a coating within the scope of the present application, which can further improve the pass rate of the lithium-ion battery puncture test, indicating that the safety performance of the lithium-ion battery is further improved.

[0113] The type of inorganic particles in the coating usually affects the safety performance of the lithium-ion battery. From Example 2-1 to Example 2-3, it can be seen that the coating includes inorganic particles within the scope of this application, and the lithium-ion battery has a higher puncture test pass rate, indicating that the safety performance of the lithium-ion battery is further improved.

[0114] The type of polymer in the coating usually affects the safety performance of the lithium-ion battery. From Example 2-4 to Example 2-5, it can be seen that the coating includes a polymer within the scope of this application, and the lithium-ion battery has a higher puncture test pass rate, indicating that the safety performance of the lithium-ion battery is further improved.

[0115] Table 3 Note: “ / ” in Table 3 indicates no relevant parameters.

[0116] It can be seen from Examples 1-11, 3-12, and 3-13 that further introducing silicon-containing additives into the electrolyte can further improve the pass rate of the lithium-ion battery puncture test, indicating that the safety performance of the lithium-ion battery is further improved.

[0117] It can be seen from Examples 2-1 and 3-1 to 3-11 that, on the basis of the isolation membrane including the coating within the scope of this application, further introducing silicon-containing additives into the electrolyte can further improve the pass rate of the lithium-ion battery puncture test, indicating that the safety performance of the lithium-ion battery is further improved.

[0118] The mass percentage e% of silicon-containing additives usually affects the safety performance of lithium-ion batteries. It can be seen from Examples 3-1 to 3-8 that by regulating the mass percentage e% of silicon-containing additives within the scope of this application, the lithium-ion battery has a higher puncture test pass rate, indicating that the safety performance of the lithium-ion battery is further improved.

[0119] The type of silicon-containing additives usually affects the safety performance of lithium-ion batteries. It can be seen from Examples 3-3, 3-9 to 3-11 that when the electrolyte includes silicon-containing additives within the scope of this application, the lithium-ion battery has a higher puncture test pass rate, indicating that the safety performance of the lithium-ion battery is further improved.

[0120] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. An electrochemical device comprising an electrolyte, a positive electrode, a negative electrode and a separator, wherein: The electrolyte includes a first additive, which is a mixed additive. The mixed additive includes additives in the following mass ratios: (1) a carbonate-containing cyclic compound: LiBF4:LiPO2F2 = 1:0.01:0.01 to 1:20:30; and / or (2) Cyclic compounds containing sulfonic acid groups: LiBF4:LiPO2F2 = 1:0.05:0.01 to 1:5:20; Based on the mass of the electrolyte, the mass percentage of the mixed additive is x%, and 0.04≤x≤10.5; The positive electrode includes a positive electrode current collector, wherein the positive electrode current collector has an elongation at break of A%, the separator has an elongation at break of B%, and 5≤B / A≤150.

2. The electrochemical device according to claim 1, which satisfies at least one of the following characteristics: (1) Cyclic compound containing carbonate group: LiBF4:LiPO2F2=1:0.1:0.1 to 1:10:20; (2) Cyclic compounds containing sulfonic acid groups: LiBF4:LiPO2F2 = 1:0.1:0.05 to 1:2:10; (3)10≤B / A≤90.

3. The electrochemical device according to claim 1 , wherein, based on the mass of the electrolyte, the mass percentage of the carbonate group-containing cyclic compound is a%, the mass percentage of the sulfonic acid group-containing cyclic compound is b%, the mass percentage of LiBF 4 is c%, and the mass percentage of LiPO 2 F 2 is d%, which satisfies at least one of the following characteristics: (1)0.01≤a≤2； (2)0.05≤b≤3.5； (3)0.01≤c≤2； (4)0.02≤d≤3。 4 . The electrochemical device according to claim 1 , wherein the carbonate group-containing cyclic compound comprises at least one of vinylene carbonate and fluoroethylene carbonate. 5 . The electrochemical device according to claim 1 , wherein the sulfonic acid group-containing cyclic compound comprises at least one of 1,3-propane sultone, 2,4-butane sultone, or 1,4-butane sultone.

6. The electrochemical device according to any one of claims 1 to 3, wherein The positive electrode current collector satisfies at least one of the following characteristics: (1) The positive electrode current collector includes aluminum foil; (2) The thickness of the positive electrode current collector is 5 μm to 20 μm; (3) The positive electrode current collector includes trace elements, and the trace elements include at least one of silicon, copper, manganese, iron, zinc, magnesium, titanium, and vanadium. Based on the mass of the positive electrode current collector, the mass percentage of the trace elements is ≤2%.

7. The electrochemical device according to any one of claims 1 to 3, which satisfies at least one of the following characteristics: (1)1.5≤A≤8 (2)9≤B≤270。 8. The electrochemical device according to any one of claims 1 to 3, which satisfies at least one of the following characteristics: (1)1.8≤A≤7.8； (2)45≤B≤250。 9. The electrochemical device according to any one of claims 1 to 3, wherein the separator comprises a substrate and a coating provided on at least one surface of the substrate, the coating comprising at least one of inorganic particles and / or a polymer; The inorganic particles include at least one of silicon oxide, aluminum oxide, titanium oxide, zinc oxide, magnesium oxide, boehmite, magnesium hydroxide, calcium titanate, barium titanate, lithium phosphate, lithium titanium phosphate or lithium lanthanum titanate; The polymer includes at least one of polymethyl methacrylate, polyvinylidene fluoride, polytetrafluoroethylene, a copolymer of vinylidene fluoride and hexafluoropropylene, polyhexafluoropropylene or polyacrylonitrile.

10. The electrochemical device according to any one of claims 1 to 3, wherein the electrolyte further comprises a second additive, the second additive being a silicon-containing additive, the silicon-containing additive comprising methyl orthosilicate, ethyl silicate, methyltrimethoxysilane, tetrapropoxysilane, isopropyl silicate, tetraallyl silicate, tetra(2-methoxyethoxy)silane, isopropyl silicate, butyl orthosilicate, tetra(isopropenyloxy)silane, allyltriethoxysilane, allyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, 1,2-bistrimethoxysilylethane, propyltrimethoxysilane, n-hexyltrimethoxysilane, butyltrimethoxysilane, 1,6-bis(triethoxysilyl)hexane, 1,6-bistrimethoxysilylhexane, 1,10-bis(trimethoxysilyl)octane, 6-ethyl-6-(2-methoxyethoxy)-2 ,5,7,10-tetraoxa-6-silaundecane, trimethoxy(1,1,2-trimethylpropyl)-silane, bis(trimethoxysilylmethyl)ethylene, (3,3-dimethylbutyl)triethoxysilane, 3-butenetriethoxysilane, allyltriacetoxysilane, 1-(triethoxysilyl)-2-pentene, 10-alkenylundecanyltrimethoxysilane, diallyldiethoxysilane, 2-butenyltriethoxysilane, cyclopentanetrimethoxysilane, 11-cyanoundecyltrimethoxysilane, hexadecyltriethoxysilane, cyanohexyltrimethoxysilane, isobutyltriethoxysilane, isobutyltrimethoxysilane, tert-butyltrimethoxysilane or at least one of 3-cyanopropyltrimethoxysilane; based on the mass of the electrolyte, the mass percentage of the silicon-containing additive is e%, 0.04≤e≤3.

0.

11. The electrochemical device according to claim 9, wherein 0.1≤e≤1.2。 12 . An electronic device comprising the electrochemical device according to claim 1 .

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