Non-aqueous electrolyte, lithium-ion battery, battery module, battery pack, and electrical device

Abstract

The present invention relates to the technical field of batteries, and particularly to a non-aqueous electrolyte, a lithium-ion battery, a battery module, a battery pack, and an electrical device. The non-aqueous electrolyte includes a non-aqueous organic solvent, a lithium salt, and a functional additive, and the functional additive includes a compound having the structure shown in Formula I. When the electrolyte additive of the present invention is used in a lithium-ion battery, it can effectively reduce the internal resistance of the battery, inhibit the decomposition and gas generation of the electrolyte, effectively improve the high-temperature storage and high-temperature cycling performance of the battery, and at the same time can take into account the rate and low-temperature performance.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a non-aqueous electrolyte, a lithium-ion battery, a battery module, a battery pack, and an electrical device. Background Art

[0002] Since the commercialization of lithium-ion batteries, due to their advantages such as high energy density, high power density, long cycle life, and environmental friendliness, they have been widely used in the field of power batteries. At the same time, due to the diverse application environments of terminal devices, consumers have put forward higher and higher requirements for the performance of lithium-ion batteries, such as long cycle life and normal use under high and low temperature conditions. However, performance degradation (such as capacity loss and reduced cycle life) and safety hazards (such as short circuits caused by diaphragm melting) under high temperature environments are the core issues restricting their development. Specifically, high temperature accelerates battery aging. At the same time, due to the poor thermal stability of lithium salts and organic solvents at high temperatures, the battery performance also decreases accordingly. In this case, the electrolyte is prone to decomposition and generates a large amount of gas, resulting in battery swelling, which in turn affects its performance and safety. Therefore, it has become an urgent task to develop an electrolyte that can remain stable in high temperature environments to address this challenge.

[0003] Organic phosphate flame-retardant electrolytes are the earliest used and most studied flame-retardant electrolytes in lithium-ion batteries, which mainly prevent combustion through free radical elimination reactions, including alkyl phosphate esters (such as TMP, TEP, etc.), aryl phosphate esters, phosphite esters, phosphonitriles, phosphorus-fluorine compounds, etc. Among them, fluorine-substituted phosphate ester compounds may have unique physical and chemical properties due to the presence of both phosphorus atoms and fluorine atoms connected thereto and a cyclic structure. However, precisely because of the large number of functional groups, a large adjustment space for substitution groups and structures, and the interactions between various substances in the specific electrolyte formulation, the specific direction of improving the electrolyte performance by fluorine-substituted phosphate ester compounds is not clear. Coupled with the novel structure of fluorine-substituted compounds and being restricted by the preparation process, their application in electrolytes is not extensive.

[0004] As disclosed in the patent with the application publication number CN116063352A, trifluorinated cyclic phosphate compounds are disclosed, and the focus is on studying the preparation methods of such compounds. Although it is mentioned that such compounds can be used as additives for lithium battery electrolytes, no actual application conditions are given, nor any data is provided to illustrate their specific effects in improving the performance of electrolytes. CN116284140A discloses difluorinated cyclic phosphate compounds, and the emphasis is also on studying their preparation methods. Although it is mentioned that such fluorinated cyclic phosphate compounds can be used as a new type of additive for lithium-ion battery electrolytes, which helps to improve the cycle life of lithium-ion batteries and improve the high-temperature cycle performance of lithium-ion batteries, such as having higher safety, higher energy density, and higher rate performance, no experimental data is given to prove the actual effects of the above compounds in practical applications. Due to the influence of other functional groups and other substances in the electrolyte formulation on fluorine atoms, phosphorus atoms, and the cyclic structure, there are defects in the limited improvement of various properties of the electrolyte in practical applications. Summary of the Invention

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a non-aqueous electrolyte, a lithium-ion battery, a battery module, a battery pack, and an electrical device. When the electrolyte additive of the present invention is used in a lithium-ion battery, it can effectively reduce the internal resistance of the battery, inhibit the decomposition and gas generation of the electrolyte, effectively improve the high-temperature storage and high-temperature cycle performance of the battery, and at the same time can take into account the rate and low-temperature performance.

[0006] To achieve the above object and other related objects, the first aspect of the present invention provides a non-aqueous electrolyte, which includes a lithium salt, a non-aqueous organic solvent, and a functional additive, and the functional additive includes a compound having the structure shown in Formula I.

[0007] ;

[0008] Wherein, R1, R2, R3, and R4 are each independently selected from any one of hydrogen, carbonyl, substituted or unsubstituted C1-C10 straight-chain or branched-chain alkyl groups, substituted or unsubstituted C2-C10 alkenyl groups, substituted or unsubstituted C2-C10 alkynyl groups, and substituted or unsubstituted C1-C10 alkoxy groups; or R3 and R4 are bonded to form a bridged ring; A is selected from O or S.

[0009] The second aspect of the present invention provides a lithium-ion battery, which includes a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and the non-aqueous electrolyte of the first aspect of the present invention.

[0010] The third aspect of the present invention provides a battery module, which includes the lithium-ion battery described in the second aspect of the present invention.

[0011] The fourth aspect of the present invention provides a battery pack, which includes the battery module described in the third aspect of the present invention.

[0012] The fifth aspect of the present invention provides an electrical device, including the lithium-ion battery described in the second aspect of the present invention. The lithium-ion battery is used as the power source of the electrical device, and the electrical device includes a mobile device, an electric vehicle, an electric train, a satellite, a ship, and an energy storage system.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] (1) The present invention uses a cyclic fluorinated oxythiophosphate compound having the structure shown in Formula I as an electrolyte additive. It has good film-forming properties, can form a dense and stable passivation film on the positive and negative electrodes, and introduces P and S elements into the passivation film, improving the ionic conductivity, reducing the interfacial impedance, and effectively improving the cycle performance of the lithium-ion battery; and the cyclic fluorinated oxythiophosphate compound has a low oxidation potential and can preferentially polymerize on the surface of the positive electrode to form a stable solid electrolyte interface (CEI film), which can significantly reduce the interfacial impedance of the positive electrode, is beneficial to the migration of lithium ions, and the formed CEI film can effectively inhibit the side reaction between the electrolyte and the positive electrode, inhibit the dissolution of transition metal ions, and improve the stability of the positive electrode interface;

[0015] (2) In addition to preferentially forming a film on the positive electrode, the cyclic fluorinated oxythiophosphate compound also has a high reduction potential and can preferentially form a thin and stable solid electrolyte interface (SEI film) on the negative electrode. The SEI film is mainly composed of inorganic components and can provide high interfacial chemical stability and interfacial stability; the cyclic ether structure can decompose on the negative electrode to form a polymer structure similar to PEO, which is beneficial to the rapid transmission of lithium ions, thereby reducing the impedance. The formed SEI film can effectively isolate the contact between the electrolyte and the negative electrode material, inhibit the decomposition and gas generation of the electrolyte, and further improve the high-temperature performance;

[0016] (3) The cyclic fluorinated oxythiophosphate compound used in the present invention is used in combination with other additives, can regulate the reduction potential of other additives, inhibit the film-forming reaction of other additives, play a role in protecting other additives, and enable other additives to continuously act in the electrolyte, improving the long-cycle performance. The synergistic effect of these additives can reduce the impedance of the lithium-ion battery, improve the ionic conductivity, improve the initial efficiency, and improve the high-temperature storage performance and high-temperature cycle performance. Detailed Embodiments

[0017] Hereinafter, the embodiments of the non-aqueous electrolyte, lithium-ion battery, battery module, battery pack, and electrical device provided by the present invention will be described in detail.

[0018] The "range" disclosed in this application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, ranges of 60-110 and 80-120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise specified, the numerical range "a~b" represents an abbreviated representation of any real number combination between a and b, where both a and b are real numbers. For example, the numerical range "0~5" means that all real numbers between "0~5" have been fully listed herein, and "0~5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0019] The present invention provides a non-aqueous electrolyte, a lithium-ion battery, a battery module, a battery pack, and an electrical device. In the non-aqueous electrolyte of this application, the components of the additive cooperate with each other, can effectively reduce the internal resistance of the battery, inhibit the decomposition and gas generation of the electrolyte, effectively improve the high-temperature storage and high-temperature cycling performance of the battery, and at the same time can take into account the rate performance and low-temperature performance. On this basis, this application is completed.

[0020]

Non-aqueous electrolyte

[0021] The first aspect of the present invention provides a non-aqueous electrolyte, comprising a non-aqueous organic solvent, a lithium salt, and a functional additive, and the functional additive comprises a compound having the structure shown in Formula I.

[0022] The compound having the structure shown in Formula I is:

[0023] ;

[0024] Wherein, R1, R2, R3, and R4 are each independently selected from any one of hydrogen, carbonyl, substituted or unsubstituted C1-C10 straight-chain or branched-chain alkyl, substituted or unsubstituted C2-C10 alkenyl, substituted or unsubstituted C2-C10 alkynyl, and substituted or unsubstituted C1-C10 alkoxy; or R3 and R4 are bonded to form a bridged ring; A is selected from O or S.

[0025] The compound with the structure shown in Formula I of the present invention has good film-forming properties, can form a dense and stable passivation film on the positive and negative electrodes, and will introduce P and S elements into the passivation film, improve the ionic conductivity, reduce the interfacial impedance, and effectively improve the cycling performance of the lithium-ion battery; moreover, the cyclic fluorinated oxythiophosphorus compound with the structure shown in Formula I has a low oxidation potential, can preferentially polymerize on the surface of the positive electrode to form a stable solid electrolyte interface (CEI film), can significantly reduce the positive electrode interfacial impedance, is beneficial to the migration of lithium ions, and the formed CEI film can effectively inhibit the side reaction between the electrolyte and the positive electrode, inhibit the dissolution of transition metal ions, and improve the positive electrode interfacial stability.

[0026] In the compound with the structure shown in Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from hydrogen.

[0027] In the compound with the structure shown in Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from carbonyl groups.

[0028] In the compound with the structure shown in Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C1-C10 straight-chain or branched-chain alkyl groups. In specific embodiments, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C1-C8, C1-C6, C1-C4, or C1-C2 straight-chain or branched-chain alkyl groups. Optionally, R1, R2, R3, and R4 are each independently selected from methyl, ethyl, propyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, or sec-butyl, etc. Optionally, the alkyl group can be substituted, and the substituents can be, for example, fluorine, chlorine, bromine, iodine, methoxy, siloxanyl, trifluoromethyl, trifluoromethoxy, cyano, etc.

[0029] In the compound with the structure shown in Formula I of the present invention, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C2-C10 alkenyl groups. In specific embodiments, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C2-C8, C2-C6, or C2-C4 alkenyl groups. Optionally, R1, R2, R3, and R4 are each independently selected from vinyl, propenyl, isopropenyl, butenyl, isobutenyl, tert-butenyl, or sec-butenyl, etc. Optionally, the alkenyl group can be substituted, and the substituents can be, for example, fluorine, chlorine, bromine, iodine, methoxy, siloxanyl, trifluoromethyl, trifluoromethoxy, cyano, etc.

[0030] In the compound of the structure shown by Formula I according to the present invention, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C2-C10 alkynyl groups. In specific embodiments, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C2-C8, C2-C6, or C2-C4 alkynyl groups. Optionally, R1, R2, R3, and R4 are each independently selected from ethynyl, propynyl, isopropylpropynyl, butynyl, isobutynyl, tert-butynyl, or sec-butynyl, etc. Optionally, the alkynyl group can be substituted, and the substituents can be, for example, fluorine, chlorine, bromine, iodine, methoxy, siloxanyl, trifluoromethyl, trifluoromethoxy, cyano, etc.

[0031] In the compound of the structure shown by Formula I according to the present invention, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C1-C10 alkoxy groups. In specific embodiments, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted C1-C8, C1-C6, C1-C4, or C1-C2 alkoxy groups. Optionally, the alkoxy group can be substituted, and the substituents can be, for example, fluorine, chlorine, bromine, iodine, siloxanyl, trifluoromethyl, trifluoromethoxy, cyano, etc.

[0032] In the compound of the structure shown by Formula I according to the present invention, R3 and R4 are bonded to form a bridged ring.

[0033] In the compound of the structure shown by Formula I according to the present invention, A is selected from O or S.

[0034] The cyclic ether structure can decompose at the negative electrode to form a polymer structure similar to PEO, which is beneficial to the rapid transmission of lithium ions, thereby reducing the impedance. The formed SEI film can effectively isolate the electrolyte from contacting the negative electrode material, inhibit the decomposition of the electrolyte to generate gas, and further improve the high-temperature performance.

[0035] In some optional embodiments of the present invention, R1, R2, R3, and R4 are each independently selected from any one of hydrogen, carbonyl, substituted or unsubstituted C1-C4 straight-chain or branched-chain alkyl groups, substituted or unsubstituted C2-C4 alkenyl groups, substituted or unsubstituted C2-C4 alkynyl groups, and substituted or unsubstituted C1-C4 alkoxy groups; or R3 and R4 are bonded to form a bridged ring.

[0036] In some optional embodiments of the present invention, R1, R2, R3, and R4 are each independently selected from any one of hydrogen, carbonyl, substituted or unsubstituted C1-C2 straight-chain or branched-chain alkyl groups, substituted or unsubstituted C2-C3 alkenyl groups, substituted or unsubstituted C2-C3 alkynyl groups, and substituted or unsubstituted C1-C2 alkoxy groups; or R3 and R4 are bonded to form a bridged ring.

[0037] In some alternative embodiments of the present invention, R1, R2, R3, and R4 are each independently selected from any one of hydrogen, carbonyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, methoxy-substituted methyl, vinyl, allyl, ethynyl, propynyl, methoxy, and ethoxy; or R3 and R4 are bonded to form a bridged ring.

[0038] In some alternative embodiments of the present invention, R1, R2, R3, and R4 are each independently selected from hydrogen, carbonyl, methyl, ethyl, vinyl, ethynyl, methoxy, methoxy-substituted methyl, or R3 and R4 are bonded to form a bridged ring.

[0039] In the non-aqueous electrolyte provided by the present invention, further, the compound of the structure shown in Formula I is selected from the following structures:

[0040] ;

[0041] ;

[0042] 。

[0043] In the non-aqueous electrolyte provided by the present invention, the functional additive in the non-aqueous electrolyte may include the compound shown in Formula I, or may include any one or a combination of more than one of the compounds shown in the above Compounds 1 to Compound 17.

[0044] In the non-aqueous electrolyte provided by the present invention, the mass ratio of the compound of the structure shown in Formula I in the non-aqueous electrolyte is 0.5% to 2%. In some embodiments, the mass ratio of the compound of the structure shown in Formula I in the non-aqueous electrolyte may also be 0.5% to 1%, 0.5% to 1.5%, 0.5% to 2%, 1% to 1.5%, 1% to 2%, or 1.5% to 2%, etc. Within the above range, the compound of the structure shown in Formula I can preferentially form a stable and dense passivation film on the surfaces of the positive and negative electrodes, reduce the interfacial impedance, inhibit the decomposition and gas generation of the electrolyte, and improve the high-temperature performance of the battery cell; if the proportion of the compound of the structure shown in Formula I is too high (the mass ratio in the non-aqueous electrolyte is higher than 2%), it will cause the film to be too thick, increase the interfacial impedance, and deteriorate the performance of the battery cell. If the proportion of the compound of the structure shown in Formula I is too low (the mass ratio in the non-aqueous electrolyte is lower than 0.5%), it will result in a poor film-forming effect and have no obvious improvement effect on the high-temperature performance.

[0045] In the non-aqueous electrolyte provided by the present invention, the functional additive further includes other additives, and the other additives are selected from one or a combination of more than one of lithium bis(fluorosulfonyl)imide, tetraethenylsilane, lithium trifluoromethanesulfonate, lithium fluorosulfonate, 2-propynyl methanesulfonate, methylene methanedisulfonate, N-methylbis(fluorosulfonyl)imide, 4,5-dicyano-2-methylimidazole, and 4,5-dicyano-2-ethylimidazole. Optionally, the other additives are selected from one or a combination of more than one of lithium bis(fluorosulfonyl)imide, lithium fluorosulfonate, 2-propynyl methanesulfonate, methylene methanedisulfonate, 4,5-dicyano-2-methylimidazole, and 4,5-dicyano-2-ethylimidazole. Preferably, the other additives are selected from one or a combination of more than one of lithium bis(fluorosulfonyl)imide (LiFSI), 2-propynyl methanesulfonate (PMS), lithium fluorosulfonate (LiOf), and methylene methanedisulfonate (MMDS). More specifically, it can be a combination of lithium bis(fluorosulfonyl)imide (LiFSI) and 2-propynyl methanesulfonate (PMS), a combination of 2-propynyl methanesulfonate (PMS) and lithium fluorosulfonate, or a combination of lithium fluorosulfonate (LiOf) and methylene methanedisulfonate (MMDS). When the compound with the structure shown in Formula I is used in combination with other additives in the electrolyte, the performance of the lithium-ion battery can be further improved. Specifically: The other additives of the present invention cooperate with the compound with the structure shown in Formula I, and can have an obvious synergistic effect, can regulate the reduction potential of other additives, inhibit the film-forming reaction of other additives, play a role in protecting other additives, and enable other additives to continuously act in the electrolyte, improving the long-cycle performance; the synergistic effect of these additives can reduce the impedance of the lithium-ion battery, increase the ionic conductivity, increase the initial efficiency, and improve the high-temperature storage performance and high-temperature cycling performance.

[0046] In the non-aqueous electrolyte provided by the present invention, the mass ratio of the other additives in the non-aqueous electrolyte is 1% to 5%. In some embodiments, the mass ratio of the other additives in the non-aqueous electrolyte can also be, for example, 1% to 4%, 1% to 3%, 2% to 4%, 1% to 2%, 2% to 3%, 3% to 4%, or 4% to 5%, etc. Within the above range, the other additives can modify the positive and negative electrode interface films, inhibit gas generation, and reduce impedance, etc. If the proportion of the other additives is too high (the mass ratio in the non-aqueous electrolyte is higher than 5%), it may lead to too thick film formation and increased impedance, etc. If the proportion of the other additives is too low (the mass ratio in the non-aqueous electrolyte is lower than 1%), the film-forming effect is poor, the interface impedance cannot be effectively reduced, and the improvement of the cell performance is not obvious.

[0047] Further optionally, when the other additive is selected from lithium bis(fluorosulfonyl)imide (LiFSI), 2-propynyl methanesulfonate (PMS), lithium fluorosulfonate (LiOf), or methylene methanedisulfonate (MMDS), the mass percentage of lithium bis(fluorosulfonyl)imide in the non-aqueous electrolyte is 0.5% to 3%, and can be optionally 0.5% to 1%, 0.5% to 1.5%, 0.5% to 2%, 0.5% to 2.5%, 1% to 1.5%, 1% to 2%, 1% to 2.5%, 1% to 3%, 1.5% to 2.5%, 1.5% to 2%, 2% to 2.5%, or 2.5% to 3%, etc. The mass percentage of 2-propynyl methanesulfonate in the non-aqueous electrolyte is 0.5% to 2%, and can be optionally 0.5% to 1%, 0.5% to 1.5%, 1% to 1.5%, 1% to 2%, or 1.5% to 2%, etc. The mass percentage of lithium fluorosulfonate in the non-aqueous electrolyte is 0.5% to 3%, and can be optionally 0.5% to 1%, 0.5% to 1.5%, 0.5% to 2%, 0.5% to 2.5%, 1% to 1.5%, 1% to 2%, 1% to 2.5%, 1% to 3%, 1.5% to 2.5%, 1.5% to 2%, 2% to 2.5%, or 2.5% to 3%, etc. The mass percentage of methylene methanedisulfonate in the non-aqueous electrolyte is 0.5% to 2%, and can be optionally 0.5% to 1%, 0.5% to 1.5%, 1% to 1.5%, 1% to 2%, or 1.5% to 2%, etc.

[0048] In the non-aqueous electrolyte provided by the present invention, the lithium salt is selected from one or a combination of more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorosilicate, lithium tetrachloroaluminate, lithium bis(oxalato)borate, lithium chloride, lithium bromide, lithium iodide, lithium trifluoromethanesulfonate, and lithium bis(trifluoromethylsulfonyl)imide. Preferably, the lithium salt is selected from lithium hexafluorophosphate (LiPF6).

[0049] In the non-aqueous electrolyte provided by the present invention, the concentration of the lithium salt in the non-aqueous electrolyte is 0.5 mol / L to 2 mol / L. In some embodiments, the concentration of the lithium salt in the non-aqueous electrolyte can also be 0.5 mol / L to 1 mol / L, 1 mol / L to 1.5 mol / L, or 1.5 mol / L to 2 mol / L, etc. Within the above range, high lithium ion conductivity and stable lithium ion transport can be ensured. If the proportion of the lithium salt is too high (the content in the non-aqueous electrolyte is higher than 2 mol / L), incomplete dissociation of the lithium salt will occur, the viscosity of the electrolyte will be too high, which will hinder the transport of lithium ions and reduce the rate performance and low-temperature performance. If the proportion of the lithium salt is too low (the content in the non-aqueous electrolyte is lower than 0.5 mol / L), the electrochemical stability of the electrolyte will be poor.

[0050] In the non-aqueous electrolyte provided by the present invention, the non-aqueous organic solvent is selected from cyclic carbonates and / or chain carbonates. Optionally, the non-aqueous organic solvent is selected from one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, and γ-butyrolactone. Further optionally, the non-aqueous organic solvent is selected from ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and ethylene carbonate (EC), and the volume ratio of ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and ethylene carbonate (EC) is (4 - 6):(1 - 3):(2 - 4), for example, it can be 5:(1 - 3):(2 - 4), (4 - 6):2:(2 - 4), or (4 - 6):(1 - 3):3.

[0051] In the non-aqueous electrolyte provided by the present invention, the mass percentage of the non-aqueous organic solvent in the non-aqueous electrolyte is 73% - 93%. In some embodiments, the mass percentage of the non-aqueous organic solvent in the non-aqueous electrolyte can also be 73% - 75%, 75% - 85%, or 85% - 93%, etc. Within the above range, the lithium salt and additives can be better dissolved. If the proportion of the non-aqueous organic solvent is too high (the mass percentage in the non-aqueous electrolyte is higher than 93%), the electrochemical stability of the electrolyte will be poor. If the proportion of the non-aqueous organic solvent is too low (the mass percentage in the non-aqueous electrolyte is lower than 73%), the dissociation of the lithium salt will be incomplete and the viscosity of the electrolyte will be too high.

[0052]

Lithium-ion battery

[0053] The second aspect of the present invention provides a lithium-ion battery, which further includes a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, and the non-aqueous electrolyte is the non-aqueous electrolyte of the first aspect of the present invention.

[0054] The positive electrode includes a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector. The positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The positive electrode active material layer includes a positive electrode active material, and the positive electrode active material layer can also include a conductive agent and a binder. The positive electrode active material can be selected from one or more combinations of lithium cobaltate, lithium manganate, lithium nickel manganate, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium iron phosphate, and lithium iron manganese phosphate. Preferably, the positive electrode active material used in this experiment is selected from lithium nickel cobalt manganate, wherein 0.5 ≤ the mole fraction of nickel < 1. Specifically, the ternary material of lithium nickel cobalt manganate can be specifically selected from LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.65 Co 0.15 Mn0.2 O2 and LiNi 0.8 Co 0.1 Mn 0.1 One or more of O2, etc. Those skilled in the art can select conductive agents and binders applicable to lithium-ion batteries in the art. Among them, the conductive agent can include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The binder can include, for example, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0055] In some embodiments, the positive electrode can be prepared in the following manner: Disperse the above-mentioned components for preparing the positive electrode, such as the positive electrode material, conductive agent, binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coat the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode can be obtained.

[0056] The negative electrode includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector. The negative electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, copper foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The negative electrode active material layer includes a negative electrode active material, and the negative electrode active material layer can also include a plasticizer, a conductive agent, and a binder. The negative electrode active material can be selected from one or a combination of silicon carbon, silicon oxide, natural graphite, artificial graphite, lithium titanate, amorphous carbon, and lithium metal. Those skilled in the art can select plasticizers, conductive agents, and binders applicable to lithium-ion batteries in the art. Among them, the conductive agent can be selected from, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The binder can be selected from, for example, at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), carboxymethyl chitosan (CMCS), and sodium carboxymethyl cellulose (CMC-Na).

[0057] In some embodiments, the negative electrode can be prepared in the following manner: Disperse the above-mentioned components for preparing the negative electrode, such as the negative electrode material, conductive agent, binder, and any other components, in a solvent (such as deionized water) to form a negative electrode slurry; coat the negative electrode slurry on the negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode can be obtained.

[0058] The lithium-ion battery provided in the second aspect of the present invention can be prepared by using well-known methods in the art. For example, stack the positive electrode, separator, and negative electrode in sequence, with the separator placed between the positive and negative electrodes to play a role in isolation, and then obtain a bare battery cell by laminating; place the bare battery cell in an outer packaging case, inject a non-aqueous electrolyte after drying, and obtain a lithium-ion battery through processes such as vacuum packaging, standing, formation, and shaping.

[0059]

Battery Module

[0060] The third aspect of the present invention provides a battery module, which includes any one or several of the lithium-ion batteries described in the second aspect of the present invention. The number of lithium-ion batteries in the battery module can be adjusted according to the application and capacity of the battery module.

[0061]

Battery Pack

[0062] The fourth aspect of the present invention provides a battery pack, which includes any one or several of the battery modules described in the third aspect of the present invention. That is, the battery pack includes any one or several of the lithium-ion batteries described in the second aspect of the present invention.

[0063] The number of battery modules in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0064]

Electrical Appliance

[0065] The fifth aspect of the present invention provides an electrical appliance, which includes any one or several of the lithium-ion batteries described in the second aspect of the present invention. The lithium-ion battery can be used as the power source of the electrical appliance. Preferably, the electrical appliance can be, but is not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc.

[0066] The beneficial effects of the present invention are further described below in conjunction with embodiments.

[0067] In order to make the invention object, technical solution, and beneficial technical effects of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. However, it should be understood that the embodiments of the present invention are only for explaining the present invention and are not for limiting the present invention, and the embodiments of the present invention are not limited to the embodiments given in the specification. For the embodiments without specific experimental conditions or operation conditions noted, they are made under conventional conditions or according to the conditions recommended by the material suppliers.

[0068] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combined steps or the insertion of other method steps between the clearly mentioned steps, unless otherwise stated; it should also be understood that the combined connection relationship between one or more devices / electrical devices mentioned in the present invention does not exclude the existence of other devices / devices before and after the combined devices / devices or the insertion of other devices / devices between the two clearly mentioned devices / devices, unless otherwise stated. Moreover, unless otherwise stated, the numbers of the method steps are only convenient tools for identifying the method steps, rather than limiting the arrangement order of the method steps or the scope of implementation of the present invention. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope of implementation of the present invention.

[0069] In the following examples, the reagents, materials, and instruments used can be obtained commercially without special instructions.

[0070] In the examples and comparative examples of the present invention, the lithium-ion battery cathode material used is LiNi 0.5 Co 0.2 Mn 0.3 O2 (lithium nickel cobalt manganese oxide, where 0.5 ≤ the mole fraction of nickel < 1), the anode uses artificial graphite, the electrolyte injection volume of each battery is 4 g, and the following different electrolytes are selected as examples, and Comparative Example 1 is a conventional electrolyte.

[0071] Example 1

[0072] Preparation of electrolyte:

[0073] In a dry room, prepare the electrolyte (the dew point of the preparation environment is lower than -40 °C). Mix ethylene methyl carbonate (EMC), diethyl carbonate (DEC), and ethylene carbonate (EC) in a volume ratio of 5:2:3 as the organic solvent, and a total of 100 mL is prepared. Add the lithium salt LiPF6 to this solvent to make its molar concentration 1.1 M / L, and add 1% of Compound 1, 1% of lithium bis(fluorosulfonyl)imide (1% LiFSI), and 0.5% of 2-propynyl methanesulfonate (0.5% PMS) based on the total mass of the above electrolyte, and stir until completely dissolved to obtain the lithium-ion battery electrolyte of Example 1. Inject the prepared electrolyte into a soft-pack battery, and after processes such as standing, formation, and grading, obtain lithium-ion battery A.

[0074] Example 2

[0075] Preparation of electrolyte:

[0076] Different from Example 1, 1% of Compound 1 was replaced with 0.5% of Compound 1 to obtain the lithium-ion battery electrolyte of Example 2. The prepared electrolyte was injected into a soft-pack battery. After processes such as standing, formation, and grading, lithium-ion battery B was obtained.

[0077] Example 3

[0078] Preparation of electrolyte:

[0079] Different from Example 1, 1% of Compound 1 was replaced with 2% of Compound 1 to obtain the lithium-ion battery electrolyte of Example 3. The prepared electrolyte was injected into a soft-pack battery. After processes such as standing, formation, and grading, lithium-ion battery C was obtained.

[0080] Example 4

[0081] Preparation of electrolyte:

[0082] Different from Example 1, 1% of lithium bis(fluorosulfonyl)imide (1% LiFSI) and 0.5% of 2-propynyl methanesulfonate (0.5% PMS) were replaced with 2% of lithium bis(fluorosulfonyl)imide (2% LiFSI) and 1% of 2-propynyl methanesulfonate (1% PMS) to obtain the lithium-ion battery electrolyte of Example 4. The prepared electrolyte was injected into a soft-pack battery. After processes such as standing, formation, and grading, lithium-ion battery D was obtained.

[0083] Example 5

[0084] Preparation of electrolyte:

[0085] Different from Example 1, 1% of lithium bis(fluorosulfonyl)imide (1% LiFSI) and 0.5% of 2-propynyl methanesulfonate (0.5% PMS) were replaced with 1% of lithium fluorosulfonate (1% LiOf) and 0.5% of methylene methanedisulfonate (0.5% MMDS) to obtain the lithium-ion battery electrolyte of Example 5. The prepared electrolyte was injected into a soft-pack battery. After processes such as standing, formation, and grading, lithium-ion battery E was obtained.

[0086] Example 6

[0087] Preparation of electrolyte:

[0088] Different from Example 1, 1% of Compound 1 was replaced with 1% of Compound 9 to obtain the lithium-ion battery electrolyte of Example 6. The prepared electrolyte was injected into a soft-pack battery. After processes such as standing, formation, and grading, lithium-ion battery F was obtained.

[0089] Example 7

[0090] Preparation of electrolyte:

[0091] Different from Example 1, 1% of Compound 1, 1% of lithium bis(fluorosulfonyl)imide (1% LiFSI), and 0.5% of 2-propynyl methanesulfonate (0.5% PMS) were replaced with 0.5% of Compound 9, 0.5% of lithium bis(fluorosulfonyl)imide (0.5% LiFSI), and 0.5% of 2-propynyl methanesulfonate (0.5% PMS) to obtain the lithium-ion battery electrolyte of Example 7. The prepared electrolyte was injected into a soft-pack battery, and after processes such as standing, formation, and grading, lithium-ion battery G was obtained.

[0092] Example 8

[0093] Preparation of electrolyte:

[0094] Different from Example 1, 1% of Compound 1, 1% of lithium bis(fluorosulfonyl)imide (1% LiFSI), and 0.5% of 2-propynyl methanesulfonate (0.5% PMS) were replaced with 2% of Compound 9, 1% of lithium fluorosulfonate (1% LiOf), and 0.5% of 2-propynyl methanesulfonate (0.5% PMS) to obtain the lithium-ion battery electrolyte of Example 8. The prepared electrolyte was injected into a soft-pack battery, and after processes such as standing, formation, and grading, lithium-ion battery H was obtained.

[0095] Example 9

[0096] Preparation of electrolyte:

[0097] Different from Example 1, 1% of Compound 1, 1% of lithium bis(fluorosulfonyl)imide (1% LiFSI), and 0.5% of 2-propynyl methanesulfonate (0.5% PMS) were replaced with 1% of Compound 13, 1% of lithium bis(fluorosulfonyl)imide (1% LiFSI), and 1% of 2-propynyl methanesulfonate (1% PMS) to obtain the lithium-ion battery electrolyte of Example 9. The prepared electrolyte was injected into a soft-pack battery, and after processes such as standing, formation, and grading, lithium-ion battery I was obtained.

[0098] Example 10

[0099] Preparation of electrolyte:

[0100] Different from Example 1, 1% of Compound 1, 1% of lithium bis(fluorosulfonyl)imide (1% LiFSI), and 0.5% of 2-propynyl methanesulfonate (0.5% PMS) were replaced with 0.5% of Compound 13, 3% of lithium bis(fluorosulfonyl)imide (3% LiFSI), and 2% of 2-propynyl methanesulfonate (2% PMS) to obtain the electrolyte for a lithium-ion battery of Example 10. The prepared electrolyte was injected into a soft-pack battery, and after processes such as standing, formation, and grading, lithium-ion battery J was obtained.

[0101] Example 11

[0102] Preparation of electrolyte:

[0103] Different from Example 1, 1% of Compound 1, 1% of lithium bis(fluorosulfonyl)imide (1% LiFSI), and 0.5% of 2-propynyl methanesulfonate (0.5% PMS) were replaced with 2% of Compound 13, 1% of lithium fluorosulfonate (1% LiOf), and 0.5% of methylene methanedisulfonate (0.5% MMDS) to obtain the electrolyte for a lithium-ion battery of Example 11. The prepared electrolyte was injected into a soft-pack battery, and after processes such as standing, formation, and grading, lithium-ion battery K was obtained.

[0104] Comparative Example 1

[0105] Preparation of electrolyte:

[0106] An electrolyte was prepared in a dry room (the dew point of the preparation environment was lower than -40°C). Ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and ethylene carbonate (EC) were mixed at a volume ratio of 5:2:3 as the organic solvent, and a total of 100 mL was prepared. LiPF6 was added to this solvent to make its molar concentration 1.1 M / L, and 1% of lithium bis(fluorosulfonyl)imide (1% LiFSI) and 0.5% of 2-propynyl methanesulfonate (0.5% PMS) based on the total mass of the above electrolyte were added respectively, and stirred until completely dissolved to obtain the electrolyte for a lithium-ion battery of Comparative Example 1. The prepared electrolyte was injected into a soft-pack battery, and after processes such as standing, formation, and grading, lithium-ion battery L was obtained.

[0107] Comparative Example 2

[0108] Preparation of electrolyte:

[0109] Different from Comparative Example 1, 1% of lithium bis(fluorosulfonyl)imide (1% LiFSI) and 0.5% of 2-propynyl methanesulfonate (0.5% PMS) were replaced with 1% of Compound 1, and stirred until completely dissolved to obtain the electrolyte for a lithium-ion battery of Comparative Example 2. The prepared electrolyte was injected into a soft-pack battery, and after processes such as standing, formation, and grading, lithium-ion battery M was obtained.

[0110] Comparative Example 3

[0111] Preparation of the electrolyte solution:

[0112] Different from Comparative Example 1, 1% lithium bis(fluorosulfonyl)imide (1% LiFSI) and 0.5% 2-propynyl methanesulfonate (0.5% PMS) were replaced with 1% of Compound 1 and 1% lithium bis(fluorosulfonyl)imide (1% LiFSI), and stirred until completely dissolved to obtain the lithium-ion battery electrolyte of Comparative Example 3. The prepared electrolyte solution was injected into a soft-pack battery, and after processes such as standing, formation, and grading, lithium-ion battery N was obtained.

[0113] Comparative Example 4

[0114] Preparation of the electrolyte solution:

[0115] Different from Comparative Example 1, 1% lithium bis(fluorosulfonyl)imide (1% LiFSI) and 0.5% 2-propynyl methanesulfonate (0.5% PMS) were replaced with 1% of Compound 1 and 0.5% 2-propynyl methanesulfonate (0.5% PMS), and stirred until completely dissolved to obtain the lithium-ion battery electrolyte of Comparative Example 4. The prepared electrolyte solution was injected into a soft-pack battery, and after processes such as standing, formation, and grading, lithium-ion battery O was obtained.

[0116] Comparative Example 5

[0117] Preparation of the electrolyte solution:

[0118] Different from Comparative Example 1, 1% of 2,2,2-trifluoro-1,3,2-dioxaphospholane (the structural formula is shown below) was further added and stirred until completely dissolved to obtain the lithium-ion battery electrolyte of Comparative Example 5. The prepared electrolyte solution was injected into a soft-pack battery, and after processes such as standing, formation, and grading, lithium-ion battery P was obtained;

[0119]

[0120] Comparative Example 6

[0121] Preparation of the electrolyte solution:

[0122] Different from Comparative Example 1, 1% of 2,2-difluoro-2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane (the structural formula is shown below) was further added and stirred until completely dissolved to obtain the lithium-ion battery electrolyte of Comparative Example 6. The prepared electrolyte solution was injected into a soft-pack battery, and after processes such as standing, formation, and grading, lithium-ion battery Q was obtained;

[0123]

[0124] The cathode material of the lithium-ion battery used in this experiment is LiNi 0.5 Co 0.2 Mn 0.3 O2 (the cathode material is lithium nickel cobalt manganese oxide, where 0.5 ≤ the molar fraction of nickel < 1), and the anode is artificial graphite. The following experiments were carried out on the batteries obtained in Comparative Examples 1-6 and all Examples 1-11, and the test results are shown in Table 2.

[0125] 1. DC internal resistance test: For the batteries obtained in the examples and comparative examples, after the formation is completed, a DC internal resistance tester is used to conduct a DC internal resistance test.

[0126] 2. High-temperature cycle performance test: For the batteries obtained in Examples 1-11 and Comparative Examples 1-6, at 45 °C, they are charged at a constant current and constant voltage of 1C to a voltage of 4.4V and a cut-off current of 0.05C, left standing for 10 min, and then discharged at a constant current of 1C to 2.75V. The above is one charge-discharge cycle. The obtained batteries are cycled for charge and discharge at 45 °C, and the cycle ends when the discharge capacity is lower than 80% of the initial discharge capacity.

[0127] 3. High-temperature storage performance test: For the batteries obtained in Examples 1-11 and Comparative Examples 1-6, at 25 °C, they are charged at a constant current and constant voltage of 1C to a voltage of 4.4V and a cut-off current of 0.05C, and the 1C capacity Q and the battery thickness H are recorded respectively; the fully charged batteries are stored at 60 °C for 28 days, and at 25 °C, the 1C discharge capacity Q1 and the battery thickness H1 of the batteries are recorded. After the batteries are charged at a constant current and constant voltage of 1C to a voltage of 4.4V and a cut-off current of 0.05C and then discharged at a constant current of 1C to 2.75V, the 1C discharge capacity Q2 is recorded, and the capacity retention rate, recovery rate, and battery expansion rate after storage of the batteries are calculated;

[0128] The calculation formulas are as follows:

[0129] Storage capacity retention rate = Q1 / Q × 100%; Storage capacity recovery rate = Q2 / Q × 100%; Storage battery expansion rate = (H1 - H) / H × 100%.

[0130] The electrolyte formulations of Examples 1-11 and Comparative Examples 1-6 are shown in Table 1 below

[0131] Table 1

[0132]

[0133] Table 2

[0134]

[0135] Combined with Table 2, by comparing Examples 1 to 11 with Comparative Example 1, it can be seen that the compound with the structure shown in Formula I of the present invention combined with other additives can effectively reduce the internal resistance of the battery, reduce the thickness expansion rate after storage, inhibit gas generation, and improve the high-temperature performance of the battery; by comparing Examples 1 to 11 with Comparative Examples 1 to 4, it can be seen that the performance of adding a certain additive alone is far inferior to the electrolyte formulation claimed in the present invention; by comparing Examples 1 to 11 with Comparative Examples 5 to 6, it can be seen that the compound with the structure shown in Formula I of the present invention has better performance than the cyclic phosphate compounds mentioned in the background art.

[0136] The above are only the preferred embodiments of the present invention, and do not impose any formal or substantial limitations on the present invention. It should be pointed out that for those of ordinary skill in the art of this technology, without departing from the method of the present invention, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any equivalent changes, such as slight modifications, decorations, and evolutions made by those skilled in the art who are familiar with this specialty without departing from the spirit and scope of the present invention by using the technical content disclosed above, are equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications, and evolutions made to the above embodiments based on the substantial technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A non-aqueous electrolyte, characterized in that: The invention comprises a lithium salt, a non-aqueous organic solvent and a functional additive, wherein the functional additive comprises a compound having a structure shown in formula I, ； in, R1, R2, R3, and R4 are each independently selected from any one of hydrogen, carbonyl, substituted or unsubstituted C1-C10 straight or branched alkyl, substituted or unsubstituted C2-C10 alkenyl, substituted or unsubstituted C2-C10 alkynyl, and substituted or unsubstituted C1-C10 alkoxy; or R3 and R4 are bonded to form a bridged ring; A is selected from O or S; The mass proportion of the compound represented by the structure of Formula I in the non-aqueous electrolyte is 0.5% to 2%; The functional additives also include other additives, which are selected from one or more combinations of lithium bis(fluorosulfonyl)imide, tetravinylsilane, lithium trifluoromethanesulfonate, lithium fluorosulfonate, 2-propynyl methanesulfonate, methylene disulfonate, N-methyldi(fluorosulfonyl)imide, 4,5-dicyano-2-methylimidazole and 4,5-dicyano-2-ethylimidazole.

2. The non-aqueous electrolyte according to claim 1, characterized in that R1, R2, R3, and R4 are each independently selected from any one of hydrogen, carbonyl, substituted or unsubstituted C1-C4 straight or branched alkyl, substituted or unsubstituted C2-C4 alkenyl, substituted or unsubstituted C2-C4 alkynyl, and substituted or unsubstituted C1-C4 alkoxy; or R3 and R4 are bonded to form a bridged ring.

3. The non-aqueous electrolyte according to claim 1, characterized in that R1, R2, R3, and R4 are each independently selected from any one of hydrogen, carbonyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, methoxy-substituted methyl, vinyl, propenyl, ethynyl, propynyl, methoxy, and ethoxy; or R3 and R4 are bonded to form a bridged ring.

4. The non-aqueous electrolyte according to any one of claims 1 to 3, characterized in that The compound represented by the formula I is selected from any one or more of the following structures: ； ； 。 5. The non-aqueous electrolyte according to claim 1, characterized in that The other additives are selected from one or more combinations of lithium bis(fluorosulfonyl)imide, lithium fluorosulfonate, 2-propynyl methanesulfonate, methylene methanedisulfonate, 4,5-dicyano-2-methylimidazole and 4,5-dicyano-2-ethylimidazole; And / or, the other additives account for 1% to 5% by mass of the non-aqueous electrolyte.

6. The non-aqueous electrolyte according to claim 1, characterized in that The lithium salt is selected from the group consisting of one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorosilicate, lithium aluminum tetrachloride, lithium bis(oxalatoborate), lithium chloride, lithium bromide, lithium iodide, lithium trifluoromethanesulfonate, and lithium bis(trifluoromethanesulfonate)imide; and / or, the concentration of the lithium salt in the non-aqueous electrolyte is 0.5 mol / L to 2 mol / L; And / or, the non-aqueous organic solvent is selected from cyclic carbonates and / or chain carbonates; And / or, the mass proportion of the non-aqueous organic solvent in the non-aqueous electrolyte is 73% to 93%.

7. The non-aqueous electrolyte according to claim 6, characterized in that The non-aqueous organic solvent is selected from one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, and γ-butyrolactone.

8. A lithium ion battery, characterized in that: The invention comprises a positive electrode, a negative electrode, a separator arranged between the positive electrode and the negative electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is the non-aqueous electrolyte according to any one of claims 1 to 7.

9. The lithium-ion battery according to claim 8, characterized in that: The negative electrode comprises a negative electrode active material, and the negative electrode active material is selected from a combination of one or more of silicon carbon, silicon oxygen, natural graphite, artificial graphite, lithium titanate, amorphous carbon and lithium metal; And / or, the positive electrode includes a positive electrode active material, and the positive electrode active material is selected from a combination of one or more of lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate and lithium iron manganese phosphate.

10. A battery module, characterized in that: Comprising a lithium ion battery according to claim 8 or 9.

11. A battery pack, characterized in that: Comprising the battery module according to claim 10.

12. An electrical device, characterized in that: It comprises a lithium-ion battery according to claim 8 or 9, wherein the lithium-ion battery is used as a power source for the device, and the power-consuming device includes a mobile device, an electric vehicle, an electric train, a satellite, a ship and an energy storage system.

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