Cross-linked non-flammable solid electrolytes and their preparation methods and applications, batteries and their preparation methods

Abstract

This invention relates to the field of solid-state electrolyte technology, and discloses a cross-linked non-flammable solid electrolyte, its preparation method and application, and a battery and its preparation method. The solid-state electrolyte comprises a polymer matrix containing a polymer and a lithium salt, and a porous rigid support material; the polymer comprises structural unit A provided by a compound of Formula I, structural unit B provided by a flame retardant containing at least one unsaturated double bond, and structural unit C provided by a cross-linking agent containing at least two unsaturated double bonds; the compound of Formula I is selected from at least one of Formulas I-1 to I-4; the solid-state electrolyte simultaneously exhibits high room-temperature ionic conductivity and a wide electrochemical window. The introduction of a flame retardant with unsaturated double bonds into the solid-state electrolyte improves the flame retardant performance of the solid-state electrolyte while significantly reducing the volatilization loss of traditional liquid flame retardants.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte technology, specifically to a cross-linked non-flammable solid electrolyte and its preparation method and application, and a battery and its preparation method. Background Technology

[0002] Lithium-ion batteries have seen tremendous growth in mobile devices, electric vehicles, and smart grids due to their high energy density and safety. With increasing demands for longer battery life in electronic products and longer driving range in electric vehicles, the development of high-energy-density lithium-ion batteries has become an urgent market need, while the energy density of traditional electrolytes is nearing its limit. Furthermore, the organic electrolytes used in traditional liquid lithium-ion batteries pose safety hazards such as leakage, volatility, and flammability, leading to frequent safety incidents in recent years. Therefore, the safety of lithium-ion batteries urgently needs improvement. Replacing liquid electrolytes with solid-state electrolytes is an effective way to solve battery safety problems, and solid-state electrolytes have therefore received widespread attention and research.

[0003] However, existing solid electrolytes such as polyethylene oxide solid electrolytes, polyacrylonitrile solid electrolytes, polyvinylidene fluoride solid electrolytes, and polymethyl methacrylate solid electrolytes have problems such as low room temperature ionic conductivity and narrow electrochemical window (≤4V).

[0004] Furthermore, in solid-state battery systems, the electrodes and electrolytes are in solid-state contact. Compared to electrolytes that can wet the positive and negative electrode materials, solid-state electrolytes have poorer compatibility with the electrodes, resulting in higher interfacial impedance and slower lithium-ion migration within the battery. Moreover, during battery cycling, the contact between the electrolyte and electrodes deteriorates further with changes in electrode volume, leading to a continuous increase in internal resistance, increased charge-discharge polarization, and deterioration of battery performance. Therefore, improving the solid-solid contact within solid-state batteries has become a hot research topic. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of low room-temperature ionic conductivity, narrow electrochemical window, and high interfacial impedance in existing solid electrolytes. It provides a cross-linked non-flammable solid electrolyte, its preparation method and application, and a battery thereof. This cross-linked non-flammable solid electrolyte simultaneously exhibits high room-temperature ionic conductivity and a wide electrochemical window. Furthermore, a flame retardant with unsaturated double bonds is introduced into the solid electrolyte, significantly reducing the volatilization loss of traditional liquid flame retardants while improving the flame retardant performance of the solid electrolyte. The battery preparation method provided by this invention employs an in-situ method to prepare the cross-linked non-flammable solid electrolyte, thereby significantly reducing the interfacial impedance between the electrolyte and the electrode. This method is simple, rapid, and low-cost, making it suitable for large-scale industrial production.

[0006] To achieve the above objectives, the first aspect of the present invention provides a cross-linked non-flammable solid electrolyte, characterized in that the solid electrolyte comprises a polymer matrix containing a polymer and a lithium salt and a porous rigid support material;

[0007] The polymer comprises structural unit A provided by a compound of formula I, structural unit B provided by a flame retardant containing at least one unsaturated double bond, and structural unit C provided by a crosslinking agent containing at least two unsaturated double bonds;

[0008] Based on the total weight of the polymer, the content of structural unit A is 55-85 wt%, the content of structural unit B is 10-25 wt%, and the content of structural unit C is 5-20 wt%.

[0009] The compound represented by Formula I is selected from at least one of Formulas I-1 to I-4;

[0010]

[0011] Where X is C, S or Si; when X is C or Si, z = 0; when X is S, z = 0 or 1; m is an integer from 0 to 10, and n is 0 or 1; R1 is H or a C1-C10 alkyl group; R2 is H or a C1-C10 alkyl group.

[0012] A second aspect of the present invention provides a method for preparing a cross-linked non-flammable solid electrolyte, characterized in that the preparation method includes the following steps:

[0013] (1) The monomer, initiator and lithium salt are stirred and mixed to obtain a precursor solution;

[0014] (2) After impregnating or spraying the porous rigid support material with the precursor solution, the material is left to stand and then subjected to a polymerization reaction to obtain the cross-linked non-flammable solid electrolyte.

[0015] The polymer monomer includes a compound of Formula I, a flame retardant containing at least one unsaturated double bond, and a crosslinking agent containing at least two unsaturated double bonds;

[0016] The compound represented by Formula I is selected from at least one of Formulas I-1 to I-4;

[0017]

[0018] Where X is C, S, or Si; when X is C or Si, z = 0; when X is S, z = 0 or 1; m is an integer from 0 to 10, and n is 0 or 1; R1 is H or a C1-C10 alkyl group; R2 is H or a C1-C10 alkyl group.

[0019] Based on the total weight of the polymer monomers, the amount of the compound represented by Formula I is 55-85 wt%, the amount of the flame retardant containing at least one unsaturated double bond is 10-25 wt%, and the amount of the crosslinking agent containing at least two unsaturated double bonds is 5-20 wt%.

[0020] The amount of initiator is 0.1-1 wt% based on the total weight of the polymerizable monomers.

[0021] A third aspect of the present invention provides a cross-linked non-flammable solid electrolyte prepared by the above preparation method.

[0022] A fourth aspect of the present invention provides an application of the above-mentioned cross-linked non-flammable solid electrolyte in a battery.

[0023] A fifth aspect of the present invention provides a battery, characterized in that the battery comprises the above-mentioned cross-linked non-flammable solid electrolyte.

[0024] The sixth aspect of the present invention provides a method for preparing a lithium-ion battery, characterized in that the method includes the following steps:

[0025] S1. The monomer, initiator and lithium salt are stirred and mixed to obtain a precursor solution;

[0026] S2. After impregnating or spraying the porous rigid support material with the precursor solution, the impregnated porous rigid support material or the sprayed porous rigid support material is taken out.

[0027] S3. The positive electrode sheet, the impregnated porous rigid support material or the sprayed porous rigid support material and the negative electrode sheet are stacked and assembled to obtain a battery system. The battery system is then subjected to static and polymerization reactions to obtain the battery.

[0028] The polymer monomer includes a compound of Formula I, a flame retardant containing at least one unsaturated double bond, and a crosslinking agent containing at least two unsaturated double bonds;

[0029] The compound represented by Formula I is selected from at least one of Formulas I-1 to I-4;

[0030]

[0031] Where X is C, S, or Si; when X is C or Si, z = 0; when X is S, z = 0 or 1; m is an integer from 0 to 10, and n is 0 or 1; R1 is H or a C1-C10 alkyl group; R2 is H or a C1-C10 alkyl group.

[0032] Based on the total weight of the polymer monomers, the amount of the compound represented by Formula I is 55-85 wt%, the amount of the flame retardant containing at least one unsaturated double bond is 10-25 wt%, and the amount of the crosslinking agent containing at least two unsaturated double bonds is 5-20 wt%.

[0033] The amount of initiator is 0.1-1 wt% based on the total weight of the polymerizable monomers.

[0034] A seventh aspect of the present invention provides a lithium-ion battery prepared by the above-described preparation method.

[0035] Through the above technical solutions, the cross-linked non-flammable solid electrolyte, its preparation method and application, and the battery and its preparation method provided by the present invention achieve the following beneficial effects:

[0036] (1) The cross-linked non-flammable solid electrolyte obtained in this invention has high room temperature ionic conductivity and a wide electrochemical window.

[0037] (2) The cross-linked non-flammable solid electrolyte obtained by the present invention has flame-retardant properties.

[0038] (3) The present invention prepares a battery containing a cross-linked non-flammable solid electrolyte by in-situ method, which can effectively improve the compatibility between the solid electrolyte and the electrode and reduce the interface impedance.

[0039] (4) The cross-linked non-flammable solid electrolyte and battery preparation method provided by the present invention are simple and fast, and do not contain excess organic solvents. Compared with the current solid electrolyte preparation methods, there is no organic solvent volatilization step, which reduces the related heating energy consumption. Attached Figure Description

[0040] Figure 1 Bulk impedance diagrams of the solid electrolytes prepared in Comparative Example 1, Comparative Example 2 and Example 1;

[0041] Figure 2 The room temperature electrochemical window of the solid electrolytes prepared in Comparative Example 1 and Example 1;

[0042] Figure 3 The charge-discharge curves of the batteries prepared in Comparative Example 3 and Example 5 at a rate of 0.1C are shown.

[0043] Figure 4 The room temperature cycling curves are for the batteries prepared in Examples 4 and 5. Detailed Implementation

[0044] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0045] The first aspect of the present invention provides a cross-linked non-flammable solid electrolyte, characterized in that the solid electrolyte comprises a polymer matrix containing a polymer and a lithium salt and a porous rigid support material;

[0046] The polymer comprises structural unit A provided by a compound of formula I, structural unit B provided by a flame retardant containing at least one unsaturated double bond, and structural unit C provided by a crosslinking agent containing at least two unsaturated double bonds;

[0047] Based on the total weight of the polymer, the content of structural unit A is 55-85 wt%, the content of structural unit B is 10-25 wt%, and the content of structural unit C is 5-20 wt%.

[0048] The compound represented by Formula I is selected from at least one of Formulas I-1 to I-4;

[0049]

[0050] Where X is C, S or Si; when X is C or Si, z = 0; when X is S, z = 0 or 1; m is an integer from 0 to 10, and n is 0 or 1; R1 is H or a C1-C10 alkyl group; R2 is H or a C1-C10 alkyl group.

[0051] In this invention, the total content of structural unit A, structural unit B and structural unit C is 100 wt%.

[0052] In this invention, the cross-linked non-flammable solid electrolyte comprises a polymer containing specific structural units A, B, and C, a lithium salt, and a porous rigid support material, which gives the solid electrolyte high room temperature ionic conductivity, a wide electrochemical window, and excellent flame retardant properties. When used in batteries, it can significantly improve the safety performance of the batteries.

[0053] Furthermore, when the content of each structural unit in the polymer meets the above range, the cross-linked non-flammable solid electrolyte not only has sufficient functional groups for transporting lithium ions, but also has excellent flame retardant properties, thereby significantly improving the safety performance of the battery.

[0054] Furthermore, when the content of structural unit A is 60-80 wt%, the content of structural unit B is 10-20 wt%, and the content of structural unit C is 10-20 wt% based on the total weight of the polymer, the room temperature ionic conductivity, electrochemical window, and flame retardant properties of the obtained solid electrolyte are further improved when the polymer is used.

[0055] According to the present invention, in formulas (I-1) to (I-4), X is C or S; m is an integer from 0 to 5, n is 0; R1 is H; R2 is H or CH3.

[0056] According to the present invention, a portion of the polymer matrix is ​​embedded in the pores of the porous rigid support material.

[0057] In this invention, in the cross-linked non-flammable solid electrolyte, a portion of the polymer matrix is ​​embedded in the pore structure of the porous rigid support material, thereby significantly improving the bonding force between the polymer matrix and the support material and increasing the strength of the solid electrolyte.

[0058] According to the present invention, the polymer content is 75-90 wt% relative to the total weight of the polymer matrix, and the lithium salt content is 10-25 wt%.

[0059] In this invention, when the content of polymer and lithium salt in the polymer matrix meets the above-mentioned range, the ionic conductivity can be significantly improved without significantly increasing the cost.

[0060] Furthermore, the polymer content is 76-87 wt% relative to the total weight of the polymer matrix, and the lithium salt content is 13-24 wt%.

[0061] According to the present invention, the flame retardant containing at least one unsaturated double bond is selected from at least one of phosphorus-based flame retardants, halogen-based flame retardants, phosphorus-nitrogen composite flame retardants, and phosphorus-halogen composite flame retardants.

[0062] According to the present invention, the flame retardant containing at least one unsaturated double bond is selected from at least one of Formula II-1 to Formula II-4;

[0063]

[0064] In this invention, a flame retardant selected from at least one of Formula II-1 to Formula II-4 is used, the flame retardant containing at least one unsaturated double bond, which can copolymerize with the compound of Formula (I) and the crosslinking agent, thereby making it flame retardant, and thereby making the solid electrolyte have improved flame retardancy.

[0065] In this invention, a crosslinking agent containing at least two unsaturated double bonds is copolymerized with a compound of Formula I and a flame retardant containing at least one unsaturated double bond, thereby making the polymer not only flame retardant but also having high room temperature ionic conductivity.

[0066] According to the present invention, the crosslinking agent containing at least two unsaturated double bonds can be an acrylate compound and / or a methacrylate compound, preferably selected from at least one of ethoxylated bisphenol A dimethacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, polyester dimethacrylate, trimethylolpropane trimethacrylate, tetraethylene glycol diacrylate, bis(trimethylolpropane) tetraacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, four-arm polyethylene glycol acrylate, and eight-arm polyethylene glycol acrylate.

[0067] More preferably, the crosslinking agent containing at least two unsaturated double bonds is selected from at least one of ethoxylated bisphenol A dimethacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, polyester dimethacrylate, trimethylolpropane trimethacrylate, tetraethylene glycol diacrylate, and bis(trimethylolpropane)tetraacrylate.

[0068] According to the present invention, the lithium salt is selected from at least one of lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium methanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, and lithium dioxalate borate, preferably at least one of lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium difluorooxalate borate, and lithium dioxalate borate.

[0069] In this invention, the porous rigid support material refers to a thin film with a porous structure. Preferably, the porosity of the porous rigid support material is 35-65%.

[0070] According to the present invention, the porous rigid support material is selected from at least one of cellulose, glass fiber, polyethylene, polypropylene, polyamide, polyimide, 3D inorganic fast ion conductor and composite materials composed of 3D inorganic fast ion conductor and organic polymer.

[0071] In this invention, the above-mentioned material is used as a porous rigid support material for solid electrolytes, which is beneficial for forming a solid electrolyte membrane from a polymer matrix containing polymers and lithium salts, and can significantly increase the strength of the electrolyte membrane.

[0072] According to the present invention, the 3D inorganic fast ion conductor is selected from at least one of perovskite oxide fast ion conductors, anti-perovskite oxide fast ion conductors, garnet fast ion conductors, NASICON fast ion conductors, and LISICON fast ion conductors.

[0073] According to the present invention, the organic polymer is selected from at least one of polyethylene oxide, polyvinylidene fluoride, polycaprolactone, polyacrylate, polymethyl methacrylate and polyvinylpyrrolidone.

[0074] According to the present invention, the porous rigid support material is prepared by at least one of electrospinning, meltblowing and papermaking.

[0075] A second aspect of the present invention provides a method for preparing a cross-linked non-flammable solid electrolyte, characterized in that the preparation method includes the following steps:

[0076] (1) The monomer, initiator and lithium salt are stirred and mixed to obtain a precursor solution;

[0077] (2) After impregnating or spraying the porous rigid support material with the precursor solution, the material is left to stand and then subjected to a polymerization reaction to obtain the cross-linked non-flammable solid electrolyte.

[0078] The polymer monomer includes a compound of Formula I, a flame retardant containing at least one unsaturated double bond, and a crosslinking agent containing at least two unsaturated double bonds;

[0079] The compound represented by Formula I is selected from at least one of Formulas I-1 to I-4;

[0080]

[0081] Where X is C, S or Si; when X is C or Si, z = 0; when X is S, z = 0 or 1; m is an integer from 0 to 10, and n takes the value 0 or 1; R1 is H or a C1-C10 alkyl group; R2 is H or a C1-C10 alkyl group.

[0082] Based on the total weight of the polymer monomers, the amount of the compound represented by Formula I is 55-85 wt%, the amount of the flame retardant containing at least one unsaturated double bond is 10-25 wt%, and the amount of the crosslinking agent containing at least two unsaturated double bonds is 5-20 wt%.

[0083] The amount of initiator is 0.1-1 wt%, based on the total weight of the polymerized monomers.

[0084] In this invention, the above-described method is used to polymerize in situ a compound comprising the compound shown in Formula I, a flame retardant containing at least one unsaturated double bond, and a crosslinking agent containing at least two unsaturated double bonds with a porous rigid support material in the presence of an initiator and a lithium salt. The resulting solid electrolyte is then thermally polymerized to obtain a polymer-containing solid electrolyte. This allows the polymer and lithium salt to be uniformly distributed on the support material, resulting in a solid electrolyte with high room-temperature ionic conductivity, a wide electrochemical window, and excellent flame retardant properties. When used in batteries, it can significantly improve the charge-discharge performance of the batteries.

[0085] Furthermore, when the content of structural unit A is 60-80 wt%, the content of structural unit B is 10-20 wt%, and the content of structural unit C is 10-20 wt% based on the total weight of the polymer, the room temperature ionic conductivity, electrochemical window, and flame retardant properties of the obtained solid electrolyte are further improved when the polymer is used.

[0086] Furthermore, the amount of initiator is 0.1-0.8 wt% based on the total weight of the polymerizable monomers.

[0087] In this invention, the specific types and amounts of the compound represented by Formula I, the flame retardant containing at least one unsaturated double bond, and the crosslinking agent containing at least two unsaturated double bonds, as well as the specific types of the porous rigid support material, are as described in the first aspect of this invention and will not be repeated here.

[0088] In this invention, the initiator can be a conventional initiator in the art, such as at least one of azobisisobutyronitrile, ammonium persulfate, cumene hydroperoxide, and benzoyl peroxide.

[0089] According to the present invention, the amount of the polymeric monomer is 75-90 wt% and the amount of the lithium salt is 10-25 wt% based on the total weight of the precursor solution.

[0090] Furthermore, based on the total weight of the precursor solution, the amount of the polymeric monomer is 76-87 wt%, and the amount of the lithium salt is 13-24 wt%.

[0091] According to the present invention, in step (1), the mixing conditions include: a mixing time of 5-12 hours, preferably 5-10 hours.

[0092] In this invention, under the above-mentioned stirring and mixing conditions, it is possible to ensure that the polymerizing monomer, initiator, and lithium salt form a uniform precursor solution.

[0093] According to the present invention, in step (2), the conditions for impregnation include: an impregnation time of 1-3 hours, preferably 1-2 hours.

[0094] In this invention, the impregnation conditions allow the precursor solution to come into full contact with the porous rigid support material, thereby enabling the polymer matrix containing the polymer and lithium salt to be fully embedded in the pores of the porous rigid support material.

[0095] According to the present invention, the spraying conditions include: a spraying time of 0.2-2 hours, preferably 0.2-1.8 hours.

[0096] In this invention, the spraying conditions allow the precursor solution to come into full contact with the porous rigid support material, thereby enabling the polymer matrix containing the polymer and lithium salt to be fully embedded in the pores of the porous rigid support material.

[0097] According to the present invention, the conditions for settling include: a settling time of 0.5-8 hours, preferably 0.5-6 hours.

[0098] In this invention, to avoid premature polymerization of the monomers, preferably, the stirring and mixing, the impregnation, the spraying, and the standing are all carried out at room temperature.

[0099] According to the present invention, the conditions for the polymerization reaction include: a polymerization temperature of 50-120°C and a polymerization time of 0.2-15 h.

[0100] In this invention, when the polymerization reaction is carried out under the above conditions, the polymer monomers can be fully polymerized, ensuring that the obtained cross-linked non-flammable solid electrolyte has a required degree of curing.

[0101] Furthermore, the conditions for the polymerization reaction include: a polymerization temperature of 50-110℃ and a polymerization time of 0.2-12h.

[0102] A third aspect of the present invention provides a cross-linked non-flammable solid electrolyte prepared by the above-described preparation method.

[0103] A fourth aspect of the present invention provides an application of the above-mentioned cross-linked non-flammable solid electrolyte in a battery.

[0104] A fifth aspect of the present invention provides a battery, characterized in that the battery comprises the above-mentioned cross-linked non-flammable solid electrolyte.

[0105] The sixth aspect of the present invention provides a method for preparing a lithium-ion battery, characterized in that the method includes the following steps:

[0106] S1. The monomer, initiator and lithium salt are stirred and mixed to obtain a precursor solution;

[0107] S2. After impregnating or spraying the porous rigid support material with the precursor solution, the impregnated porous rigid support material or the sprayed porous rigid support material is taken out.

[0108] S3. The positive electrode sheet, the impregnated porous rigid support material or the sprayed porous rigid support material and the negative electrode sheet are stacked and assembled to obtain a battery system. The battery system is then subjected to static and polymerization reactions to obtain the battery.

[0109] The polymer monomer includes a compound of Formula I, a flame retardant containing at least one unsaturated double bond, and a crosslinking agent containing at least two unsaturated double bonds;

[0110] The compound represented by Formula I is selected from at least one of Formulas I-1 to I-4;

[0111]

[0112] Where X is C, S, or Si; when X is C or Si, z = 0; when X is S, z = 0 or 1; m is an integer from 0 to 10, and n is 0 or 1; R1 is H or a C1-C10 alkyl group; R2 is H or a C1-C10 alkyl group.

[0113] Based on the total weight of the polymer monomers, the amount of the compound represented by Formula I is 55-85 wt%, the amount of the flame retardant containing at least one unsaturated double bond is 10-25 wt%, and the amount of the crosslinking agent containing at least two unsaturated double bonds is 5-20 wt%.

[0114] The amount of initiator is 0.1-1 wt%, based on the total weight of the polymerized monomers.

[0115] In this invention, the above-described method is used to polymerize, in situ, a compound comprising Formula I, a flame retardant containing at least one unsaturated double bond, and a crosslinking agent containing at least two unsaturated double bonds, in the presence of an initiator and a lithium salt, with a porous rigid support material. This composite material is then stacked and assembled with a positive electrode and a negative electrode to obtain a battery system. Thermal polymerization is then performed to obtain a battery containing a polymer-containing solid electrolyte as the electrolyte. This allows the polymer and lithium salt to be uniformly distributed on the support material, resulting in a solid electrolyte with high room-temperature ionic conductivity, a wide electrochemical window, and excellent flame retardant properties. Furthermore, it effectively improves the compatibility between the solid electrolyte and the electrode, reduces interfacial impedance, and significantly improves the charge-discharge performance of the resulting battery.

[0116] The specific types of compounds represented by Formula I, flame retardants containing at least one unsaturated double bond, crosslinking agents containing at least two unsaturated double bonds, initiators, lithium salts, and porous rigid support materials are as follows.

[0117] According to the present invention, in step S1, the mixing conditions include: a mixing time of 5-12 hours, preferably 5-10 hours.

[0118] In this invention, under the above-mentioned stirring and mixing conditions, it is possible to ensure that the polymerizing monomer, initiator, and lithium salt form a uniform precursor solution.

[0119] According to the present invention, in step S2, the conditions for impregnation include: an impregnation time of 1-3 hours, preferably 1-2 hours.

[0120] In this invention, the impregnation conditions allow the precursor solution to come into full contact with the porous rigid support material, thereby enabling the polymer matrix containing the polymer and lithium salt to be fully embedded in the pores of the porous rigid support material.

[0121] According to the present invention, the spraying conditions include: a spraying time of 0.2-2 hours, preferably 0.2-1.8 hours.

[0122] In this invention, the spraying conditions allow the precursor solution to come into full contact with the porous rigid support material, thereby enabling the polymer matrix containing the polymer and lithium salt to be fully embedded in the pores of the porous rigid support material.

[0123] According to the present invention, in step S3, the conditions for settling include: a settling time of 0.5-8 hours, preferably 0.5-6 hours.

[0124] In this invention, to avoid premature polymerization of the monomers, preferably, the stirring and mixing, the impregnation, the spraying, and the standing are all carried out at room temperature.

[0125] According to the present invention, in step S3, the conditions of the polymerization reaction include: a polymerization temperature of 50-120°C and a polymerization time of 0.2-15h.

[0126] In this invention, when the polymerization reaction is carried out under the above conditions, the polymer monomers can be fully polymerized, ensuring that the obtained cross-linked non-flammable solid electrolyte has a required degree of curing.

[0127] Furthermore, in step S3, the conditions for the polymerization reaction include: a polymerization temperature of 50-110℃ and a polymerization time of 0.2-12h.

[0128] According to the present invention, the positive electrode is selected from at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt oxide, and lithium nickel cobalt manganese oxide.

[0129] According to the present invention, the negative electrode is selected from at least one of graphite, silicon-carbon composite material, lithium metal, and lithium metal alloy.

[0130] A seventh aspect of the present invention provides a lithium-ion battery prepared by the above-described preparation method.

[0131] The present invention will be described in detail below through embodiments. The following embodiments...

[0132] Compound 1 has the following structure:

[0133] It has the structure shown in Equation I-3, where X is C, z = 0, m = 0, n = 0, R2 is H, and it is a commercially available product;

[0134] Compound 2: has the structure shown below:

[0135] It has the structure shown in Formula I-3, where X is C, z = 0, m = 1, n = 0, R2 is CH3, and it is a commercially available product;

[0136] Compound 3: has the structure shown below:

[0137] It has the structure shown in Equation I-2, where X is S, z = 1, R1 is H, and it is a commercially available product;

[0138] Flame retardant 1: has the structure shown in Formula II-1, commercially available;

[0139] Flame retardant 2: has the structure shown in Formula II-3, commercially available;

[0140] Crosslinking agent 1: Ethoxylated trimethylolpropane triacrylate, commercially available;

[0141] Crosslinking agent 2: Polyethylene glycol diacrylate, commercially available;

[0142] Crosslinking agent 3: Trimethylolpropane trimethacrylate, commercially available;

[0143] Lithium salt 1: Lithium bis(trifluoromethanesulfonyl)imide, commercially available;

[0144] All other raw materials used in the examples and comparative examples are commercially available products.

[0145] Test case

[0146] 1. Ionic conductivity of electrolytes

[0147] A blocking electrode was fabricated by sandwiching a solid electrolyte between stainless steel electrodes and placing it within a 2025 coin cell casing. Electrochemical impedance spectroscopy was used to measure the impedance using the formula: σ = L / SR b Where L is the thickness of the electrolyte, S is the area of ​​the stainless steel sheet, and R... b The impedance is the measured value.

[0148] 2. Electrochemical window of electrolytes

[0149] An electrode was prepared by sandwiching a solid electrolyte between stainless steel as the working electrode, lithium metal as the counter electrode and reference electrode. The prepared electrode was subjected to LSV testing using an electrochemical workstation. The voltage range measured by linear sweep voltammetry was from open circuit voltage to 6.0V (vs Li). + / Li), with a scan rate of 1mV / s.

[0150] 3. Flame retardant performance test of electrolyte: Place the solid electrolyte membrane in the outer flame of an open flame and observe whether the electrolyte membrane is ignited to evaluate the flame retardant performance of the solid electrolyte.

[0151] 4. Battery charge / discharge test

[0152] Test conditions: Charge and discharge test at 0.1C rate at 25℃, and cycle performance test at 1C rate.

[0153] Example 1

[0154] (1) The polymer monomer containing compound 1, crosslinking agent 1, flame retardant 1 is uniformly mixed with initiator and lithium salt and stirred for 5 hours to obtain a precursor solution.

[0155] Of which, based on the total weight of the polymer monomers, the amount of compound 1 is 60 wt%, the amount of crosslinking agent 1 is 20 wt%, the amount of flame retardant is 20 wt%, the amount of initiator azobisisobutyronitrile is 0.1 wt%, and the amount of lithium salt is 12 wt% based on the total weight of the precursor solution.

[0156] (2) The porous cellulose support membrane was placed in the precursor solution, soaked for 2 hours, and then removed and left to stand at room temperature for 5 hours. Then, it was thermally polymerized in a vacuum oven at 60°C for 10 hours to obtain the cross-linked non-flammable solid electrolyte A1.

[0157] The ionic conductivity, electrochemical window, and flame retardancy of the cross-linked non-flammable solid electrolyte A1 were tested. Figure 1 The obtained ionic conductivity at room temperature is 2 × 10⁻⁶. -4 S / cm, electrochemical window as Figure 2 The voltage is 4.8V. When placed in an open flame, the electrolyte does not ignite or burn, indicating that the resulting cross-linked non-flammable solid electrolyte has flame-retardant properties.

[0158] Example 2

[0159] (1) The polymer monomer containing compound 2, crosslinking agent 1, and flame retardant 1 is uniformly mixed with initiator and lithium salt and stirred for 5 hours to obtain a precursor solution.

[0160] Of which, based on the total weight of the polymer monomers, the amount of compound 2 is 65 wt%, the amount of crosslinking agent 2 is 20 wt%, the amount of flame retardant 2 is 15 wt%, and the amount of the initiator ammonium persulfate is 0.5 wt%. Based on the total weight of the precursor solution, the amount of lithium salt is 15 wt%.

[0161] (2) The porous electrospun polyvinylpyrrolidone support membrane was placed in the precursor solution, soaked for 5 hours, and then removed and left to stand at room temperature for 5 hours. Then, it was thermally polymerized in a vacuum oven at 80°C for 8 hours to obtain the cross-linked non-flammable solid electrolyte A2.

[0162] The ionic conductivity, electrochemical window, and flame retardancy of the cross-linked non-flammable solid electrolyte A2 were tested. The room temperature ionic conductivity of the cross-linked non-flammable solid electrolyte A2 was found to be 1.6 × 10⁻⁶. -4 The electrolyte has an S / cm and an electrochemical window of 4.7V. When placed in an open flame, the electrolyte does not ignite or burn, indicating that the resulting cross-linked non-flammable solid electrolyte has flame-retardant properties.

[0163] Example 3

[0164] (1) The polymer monomer containing compound 3, crosslinking agent 3 and flame retardant 1 is uniformly mixed with initiator and lithium salt and stirred for 5 hours to obtain a precursor solution.

[0165] Of which, based on the total weight of the polymer monomers, the amount of compound 3 is 70 wt%, the amount of crosslinking agent 3 is 15 wt%, the amount of flame retardant 1 is 15 wt%, and the amount of initiator azobisisobutyronitrile is 0.5 wt%; based on the total weight of the precursor solution, the amount of lithium salt is 18 wt%.

[0166] (2) The porous polyamide support membrane was placed in the precursor solution, soaked for 8 hours, and then removed and left to stand at room temperature for 5 hours. Then, it was thermally polymerized in a vacuum oven at 100°C for 5 hours to obtain the cross-linked non-flammable solid electrolyte A3.

[0167] The ionic conductivity, electrochemical window, and flame retardancy of the cross-linked non-flammable solid electrolyte A3 were tested. The room temperature ionic conductivity of the cross-linked non-flammable solid electrolyte A3 was found to be 3 × 10⁻⁶. -4 S / cm, electrochemical window is 5V; when placed in an open flame, the electrolyte does not ignite or burn, and the resulting cross-linked non-flammable solid electrolyte has flame-retardant properties.

[0168] Example 4

[0169] The cross-linked non-flammable solid electrolyte A1 prepared in Example 1 was assembled into battery A1. Specifically:

[0170] Using NCM811 (LiNi) positive electrode 0.8 Co 0.1 Mn 0.1 Battery A1 was assembled using a stacked configuration of O2), a cross-linked non-flammable solid electrolyte A1, and a lithium metal anode. Cyclic performance testing was conducted on battery A1 according to the test example method. The results showed that at 1C rate, after 100 cycles, the capacity retention of A1 was 64.0%.

[0171] Example 5

[0172] S1: The polymer monomer containing compound 1, crosslinking agent 1, flame retardant 1, initiator and lithium salt are uniformly mixed and stirred for 5 hours to obtain a precursor solution.

[0173] Of these, based on the total weight of the monomers, Compound 1 is used in an amount of 60 wt%, Crosslinking Agent 1 in an amount of 20 wt%, Flame Retardant in an amount of 20 wt%, and Initiator Azobisisobutyronitrile in an amount of 0.1 wt%. Based on the total weight of the precursor solution, the amount of lithium salt is 12 wt%.

[0174] S2: Place the porous cellulose support membrane in the precursor solution and soak for 2 hours to obtain the impregnated porous cellulose support membrane.

[0175] S3: Remove the impregnated porous cellulose support membrane and use the positive electrode NCM811 (LiNi) 0.8 Co 0.1 Mn 0.1 The battery system was assembled by stacking O2-impregnated porous cellulose support membrane and lithium metal anode sheet. After standing for 5 hours, it was thermally polymerized in a vacuum oven at 60°C for 10 hours to obtain battery A2.

[0176] The charge and discharge performance of battery A2 was tested at 25℃ and 0.1C rate, and the results are as follows: Figure 3 As shown, its discharge capacity is 202 mAh / g, and the polarization of the charge-discharge curve is significantly reduced. Battery A2's cycle performance at 1C rate is as follows: Figure 4 As shown, after 100 cycles, the capacity retention rate was 72.2%, significantly higher than the capacity retention rate (64.0%) of battery A2 prepared in Example 4. This indicates that, compared to battery A1 obtained by the stacking method, battery A2 prepared by the in-situ method has good interfacial compatibility between the electrolyte and the electrode, which is beneficial to improving cycle stability.

[0177] Example 6

[0178] S1: The polymer monomer containing compound 2, crosslinking agent 1, and flame retardant 1 is uniformly mixed with initiator and lithium salt and stirred for 5 hours to obtain a precursor solution.

[0179] Of which, based on the total weight of the polymer monomers, the amount of compound 2 is 65 wt%, the amount of crosslinking agent 2 is 20 wt%, the amount of flame retardant 2 is 15 wt%, and the amount of the initiator ammonium persulfate is 0.5 wt%. Based on the total weight of the precursor solution, the amount of lithium salt is 15 wt%.

[0180] S2: The porous electrospun polyvinylpyrrolidone support membrane is placed in the precursor solution and soaked for 5 hours to obtain the impregnated porous electrospun polyvinylpyrrolidone support membrane.

[0181] S3: Remove the impregnated porous electrospun polyvinylpyrrolidone support membrane, and use the positive electrode NCM622 (LiNi) 0.6 Co 0.2 Mn 0.2 The battery system was assembled by stacking a porous electrospun polyvinylpyrrolidone support film impregnated with O2 and a lithium metal anode sheet. After standing for 5 hours, it was thermally polymerized in a vacuum oven at 80°C for 8 hours to obtain battery A5.

[0182] The charge and discharge performance of battery A3 was tested at 25℃ and 0.1C rate, and the results are as follows. Figure 4 As shown, its discharge capacity reaches 184mAh / g.

[0183] Example 7

[0184] S1: The polymer monomer containing compound 3, crosslinking agent 3 and flame retardant 1 is uniformly mixed with initiator and lithium salt and stirred for 5 hours to obtain a precursor solution.

[0185] Of which, based on the total weight of the polymer monomers, the amount of compound 3 is 70 wt%, the amount of crosslinking agent 3 is 15 wt%, the amount of flame retardant 1 is 15 wt%, and the amount of initiator azobisisobutyronitrile is 0.5 wt%; based on the total weight of the precursor solution, the amount of lithium salt is 18 wt%.

[0186] S2: The porous polyamide support membrane is placed in the precursor solution and soaked for 8 hours to obtain the impregnated porous polyamide support membrane.

[0187] S3: Remove the impregnated porous polyamide support membrane and use the positive electrode NCM811 (LiNi) 0.8 Co 0.1 Mn 0.1The battery system was assembled by stacking O2-impregnated porous polyamide support film and lithium metal anode sheet. After standing for 5 hours, it was thermally polymerized in a vacuum oven at 100°C for 5 hours to obtain battery A6.

[0188] The charge and discharge performance of battery A6 was tested at 25℃ and 0.1C rate, and the discharge capacity reached 200mAh / g.

[0189] Comparative Example 1

[0190] Step 1: Dissolve polyethylene oxide (PEO, molecular weight 500,000) and LiTFSI in acetonitrile, with a solute mass fraction of 10 wt% and LiTFSI accounting for 15 wt% of the total mass of the electrolyte membrane. Stir until homogeneous to obtain a polymer electrolyte slurry.

[0191] Step 2: The slurry is evenly coated onto a polytetrafluoroethylene plate and vacuum dried at 60°C for 12 hours to obtain the non-in-situ PEO polymer electrolyte D1.

[0192] The ionic conductivity, electrochemical window, and flame retardancy of polymer electrolyte D1 were tested, and the results are as follows: Figure 1 and Figure 2 As shown.

[0193] Depend on Figure 1 As shown, the bulk impedance of polymer electrolyte D1 at room temperature is 210 Ω, which is much higher than... Figure 1 The bulk impedance value of Example 1. Therefore, the room temperature ionic conductivity of polymer electrolyte D1 is 5.1 × 10⁻⁶. -6 The electrolyte has a low ionic conductivity (S / cm). When the test temperature is increased to 45℃, the bulk impedance of the electrolyte decreases, and the ionic conductivity becomes 1.5 × 10⁻⁶. -5 S / cm.

[0194] like Figure 2 As shown, the electrochemical window of polymer electrolyte D1 is 4V. The low electrochemical window indicates that this electrolyte cannot be used in high-voltage cathode materials.

[0195] When the polymer electrolyte D1 is placed in an open flame, the electrolyte membrane burns rapidly.

[0196] Comparative Example 2

[0197] Cross-linked solid electrolyte D2 was prepared according to the method of Example 1, except that it did not contain flame retardant 1. Cross-linked solid electrolyte D2 was obtained.

[0198] The ionic conductivity and flame retardancy of the cross-linked solid electrolyte D2 were tested. Figure 1 The impedance analysis yields a room-temperature ionic conductivity of 1.2 × 10⁻⁶. -4The S / cm is slightly lower than the ionic conductivity of A1. This is because the flame retardant introduced into the main chain of A1 has a larger molecular structure, which can effectively disrupt the crystallinity of the polymer, increase the effective free volume in the electrolyte, and facilitate the transport of lithium ions.

[0199] When the polymer electrolyte D2 is placed in the outer flame of an open flame, the electrolyte membrane burns rapidly.

[0200] Comparative Example 3

[0201] The polymer electrolyte D1 prepared in Comparative Example 1 was assembled into battery D1. Specifically:

[0202] Using NCM811 (LiNi) positive electrode 0.8 Co 0.1 Mn 0.1 Battery system D1 was assembled using a stacked configuration of O2), polymer electrolyte D1, and lithium metal anode sheet. Charge-discharge tests were performed on battery D1 according to the test example, and the results are as follows: Figure 3 As shown.

[0203] Because the polymer electrolyte D1 has low ionic conductivity at room temperature and cannot be charged and discharged, the battery prepared in step three above was tested for charge and discharge at 45°C and 0.1C rate. Figure 3 As shown, although the ionic conductivity at 45℃ is slightly improved, it is still low, resulting in a large internal resistance of the battery. Its discharge capacity is only 25mAh / g, which cannot give full play to the high voltage and high capacity characteristics of NCM811 cathode material.

[0204] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A cross-linked non-flammable solid-state electrolyte, characterized by, The solid-state electrolyte comprises a polymer matrix containing a polymer and a lithium salt and a porous rigid support material; The polymer consists of structural units A provided by a compound represented by Formula I, structural units B provided by a flame retardant containing at least one unsaturated double bond, and structural units C provided by a crosslinking agent containing at least two unsaturated double bonds; The content of the structural units A is 55-85 wt%, the content of the structural units B is 10-25 wt%, and the content of the structural units C is 5-20 wt% based on the total weight of the polymer. The compound represented by Formula I is selected from at least one of Formula I-1 to Formula I-4; Formula I-1 Formula I-2 Formula I-3 Formula I-4 In the formula, X is C, S or Si; when X is C or Si, z=0; when X is S, z=0 or 1; m is an integer of 0-10, n is 0 or 1; R1 is H or C1-C10 alkyl; R2 is H or C1-C10 alkyl. The content of the polymer is 82-90 wt% and the content of the lithium salt is 10-18 wt% based on the total weight of the polymer matrix. In the formula, X is C or S; m is an integer of 0-5, n is 0; R1 is H; R2 is H or CH3.

2. The cross-linked non-flammable solid-state electrolyte according to claim 1, wherein, The content of the structural units A is 60-80 wt%, the content of the structural units B is 10-20 wt%, and the content of the structural units C is 10-20 wt% based on the total weight of the polymer.

3. The cross-linked non-flammable solid-state electrolyte according to claim 1 or 2, wherein, The compound represented by Formula I is selected from at least one of Formula I-1 to Formula I-4; 4. The cross-linked non-flammable solid-state electrolyte according to claim 1 or 2, wherein, In the formula, X is C, S or Si; when X is C or Si, z=0; when X is S, z=0 or 1; m is an integer of 0-10, n is 0 or 1; R1 is H or C1-C10 alkyl; R2 is H or C1-C10 alkyl.

5. The cross-linked non-flammable solid-state electrolyte according to claim 1 or 2, wherein, The content of the polymer is 82-90 wt% and the content of the lithium salt is 10-18 wt% based on the total weight of the polymer matrix.

6. The cross-linked non-flammable solid-state electrolyte according to claim 1 or 2, wherein, The content of the structural units A is 60-80 wt%, the content of the structural units B is 10-20 wt%, and the content of the structural units C is 10-20 wt% based on the total weight of the polymer. Formula II-1 Formula II-2 Formula II-3 Formula II-4.

7. The crosslinking-type non-combustible solid-state electrolyte according to claim 1 or 2, wherein The compound represented by Formula I is selected from at least one of Formula I-1 to Formula I-4; 8. The cross-linked non-flammable solid-state electrolyte according to claim 1 or 2, wherein, The lithium salt is selected from at least one of lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium methanesulfonate, lithium difluorophosphate, lithium difluoro oxalate borate, lithium tetrafluoroborate, and lithium bisoxalate borate. The porous rigid support material is selected from at least one of cellulose, glass fiber, polyethylene, polypropylene, polyamide, polyimide, 3D inorganic fast ion conductor, and a composite material composed of 3D inorganic fast ion conductor and organic polymer.

9. The cross-linked non-flammable solid-state electrolyte according to claim 8, wherein, The 3D inorganic fast ion conductor is selected from at least one of a perovskite-type oxide fast ion conductor, an inverse perovskite-type oxide fast ion conductor, a garnet-type fast ion conductor, a NASICON-type fast ion conductor, and a LISICON-type fast ion conductor.

10. The cross-linked non-flammable solid-state electrolyte according to claim 9, wherein, The organic polymer is selected from at least one of polyethylene oxide, polyvinylidene fluoride, polycaprolactone, polypropylene carbonate, polymethyl methacrylate, and polyvinylpyrrolidone.

11. The crosslinking-type non-combustible solid-state electrolyte according to claim 1 or 2, wherein The porous rigid support material is prepared by at least one of electrospinning, melt blowing, and papermaking.

12. A method for producing the cross-linked non-flammable solid-state electrolyte according to any one of claims 1 to 11, characterized by, The preparation method comprises the following steps: (1) stirring and mixing a polymerization monomer, an initiator, and a lithium salt to obtain a precursor solution; (2) after the precursor solution is impregnated or sprayed on a porous rigid support material, standing, and polymerization reaction, the cross-linked non-combustible solid electrolyte is obtained; The polymerization monomer comprises a compound shown in Formula I, a flame retardant comprising at least one unsaturated double bond, and a cross-linking agent comprising at least two unsaturated double bonds; The compound shown in Formula I is used in an amount of 55-85 wt%, the flame retardant comprising at least one unsaturated double bond is used in an amount of 10-25 wt%, and the cross-linking agent comprising at least two unsaturated double bonds is used in an amount of 5-20 wt%, based on the total weight of the polymerization monomer; The initiator is used in an amount of 0.1-1 wt%, based on the total weight of the polymerization monomer; The content of the polymer is 82-90 wt% and the content of the lithium salt is 10-18 wt%, based on the total weight of the polymer matrix.

13. The production method according to claim 12, wherein In step (1), the stirring and mixing conditions comprise a mixing time of 5-12 h.

14. The production method according to claim 12 or 13, wherein In step (2), the impregnation conditions comprise an impregnation time of 1-3 h.

15. The production method according to claim 12 or 13, wherein The spraying conditions comprise a spraying time of 0.2-2 h.

16. The production method according to claim 12 or 13, wherein The standing conditions comprise a standing time of 0.5-8 h.

17. The method of making according to claim 12 or 13, wherein, The polymerization reaction conditions comprise a polymerization temperature of 50-120 °C and a polymerization time of 0.2-15 h.

18. The cross-linked non-combustible solid electrolyte prepared by the preparation method in any one of claims 12-17.

19. Use of the cross-linked non-combustible solid electrolyte in any one of claims 1-11 and 18 in a battery.

20. A lithium-ion battery, characterized by, The battery comprises the cross-linked non-combustible solid electrolyte in any one of claims 1-11 and 18.

21. A method of making a lithium-ion battery as defined in claim 20, wherein, The method comprises the following steps: S1, stirring and mixing a polymerization monomer, an initiator, and a lithium salt to obtain a precursor solution; S2, after the precursor solution is impregnated or sprayed on a porous rigid support material, taking out to obtain an impregnated porous rigid support material or a sprayed porous rigid support material; S3, stacking and assembling a positive electrode sheet, the impregnated porous rigid support material or the sprayed porous rigid support material, and a negative electrode sheet to obtain a battery system, and standing and polymerization reaction of the battery system to obtain the battery; The polymerization monomer comprises a compound shown in Formula I, a flame retardant comprising at least one unsaturated double bond, and a cross-linking agent comprising at least two unsaturated double bonds; The compound of formula I is used in an amount of 55-85 wt%, the flame retardant containing at least one unsaturated double bond is used in an amount of 10-25 wt%, and the crosslinking agent containing at least two unsaturated double bonds is used in an amount of 5-20 wt%, based on the total weight of the polymerization monomers; The initiator is used in an amount of 0.1-1 wt%, based on the total weight of the polymerization monomers. The content of the polymer is 82-90 wt% and the content of the lithium salt is 10-18 wt%, based on the total weight of the polymer matrix.

22. The method of making according to claim 21, wherein, In step S1, the stirring mixing conditions include a mixing time of 5-12 h.

23. The method of making according to claim 21, wherein, In step S2, the impregnation conditions include an impregnation time of 1-3 h.

24. The method of manufacturing according to claim 21, wherein, In step S2, the spraying conditions include a spraying time of 0.2-2 h.

25. The method of manufacturing according to claim 21, wherein, In step S3, the standing conditions include a standing time of 0.5-8 h.

26. The method of manufacturing according to claim 21, wherein, In step S3, the polymerization conditions include a polymerization temperature of 50-120 ℃ and a polymerization time of 0.2-15 h.

27. The method of manufacturing according to claim 21, wherein, The positive electrode sheet is selected from at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobaltate, and lithium nickel cobalt manganate.

28. The method of manufacturing according to claim 21, wherein, The negative electrode sheet is selected from at least one of graphite, silicon-carbon composite material, metallic lithium, and metallic lithium alloy.

29. A lithium ion battery prepared by the preparation method of any one of claims 21-28.

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