CN118185277A

CN118185277A - Film material, film, lithium ion battery and preparation method of lithium ion battery

Info

Publication number: CN118185277A
Application number: CN202211604597.1A
Authority: CN
Inventors: 玛丽亚·马丁内兹; 严润羽; 周昱; 洪响; 莱乐·梅亚韦; 尼古拉·博阿雷托
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2022-12-13
Filing date: 2022-12-13
Publication date: 2024-06-14

Abstract

Film material, film, lithium ion battery and preparation method of lithium ion battery. The film layer material comprises: polyethylene glycol dimethacrylate, sulfonamide compound and lithium salt. The sulfonamide compound can be used as a dispersing agent, so that the sulfonamide compound, polyethylene glycol dimethacrylate and lithium salt can be a uniform system. The sulfonamide compound can also be used as a plasticizer, intermolecular acting force exists between the sulfonamide compound and ether bond in polyethylene glycol dimethacrylate, and the intermolecular acting force can be used for the glass transition temperature of the polyethylene glycol dimethacrylate, so that the chain segment movement of the polyethylene glycol dimethacrylate is effectively promoted, and the film material has better Li+ conductivity. The film material has larger Li+ conductivity, and when the film material is applied to a lithium ion battery, a stable interface can be formed between the film formed by the film material and the anode/cathode, and the interface cannot be degraded along with deposition/stripping of lithium in the battery cycle process.

Description

Film material, film, lithium ion battery and preparation method of lithium ion battery

Technical Field

The application relates to the field of lithium ion batteries, in particular to a membrane material, a membrane, a lithium ion battery and a preparation method of the lithium ion battery.

Background

The lithium ion battery (lithium ion cells and batteries) includes: positive electrode, negative electrode and electrolyte. Lithium ion batteries rely on the back and forth exfoliation or deposition of lithium ions (li+) between a positive electrode and a negative electrode to effect charging or discharging of the battery.

The positive electrode and the negative electrode are generally connected through an electrolyte, and the electrolyte plays roles in conducting Li+ and current between the positive electrode and the negative electrode as an important component of the lithium ion battery.

The existing electrolyte mostly adopts high molecular weight polymers, the dispersion performance of the high molecular weight polymers is poor, small molecular solvents are needed to be added for dispersion, the existence of the small molecular solvents can have adverse effect on the cycle performance of the lithium ion battery, and the Li+ conductivity of the high molecular weight polymers is low.

Disclosure of Invention

The embodiment of the application provides a film material, a film, a lithium ion battery and a preparation method of the lithium ion battery. The membrane material comprises polyethylene glycol dimethacrylate, sulfonamide compounds and lithium salt, so that the membrane material has higher Li+ conductivity.

A first aspect of an embodiment of the present application provides a film material, including: polyethylene glycol dimethacrylate, sulfonamide compound and lithium salt.

According to the implementation mode, the sulfonamide compound can be used as a polyethylene glycol dimethacrylate dispersing agent, so that the sulfonamide compound, the polyethylene glycol dimethacrylate and the lithium salt can form a uniform system. The film material provided by the implementation mode does not need to adopt a small molecular solvent, so that the problem caused by the residual small molecular solvent does not exist.

The sulfonamide compound can also be used as a plasticizer of polyethylene glycol dimethacrylate, intermolecular acting force exists between the sulfonamide compound and ether bond in the polyethylene glycol dimethacrylate, and the intermolecular acting force can be used for the glass transition temperature of the polyethylene glycol dimethacrylate, so that the segment movement of the polyethylene glycol dimethacrylate is effectively promoted, and the film material has better Li+ conductivity. Because the glass transition temperature of the polyethylene glycol dimethacrylate is reduced, the film material provided by the implementation mode can show larger Li+ conductivity at room temperature, low temperature and high temperature.

The film material has larger Li+ conductivity, and when the film material is applied to a lithium ion battery, a serious charge layer is not formed between the film formed by the film material and the positive electrode/negative electrode of lithium ions. The film layer formed by the film layer material can form a stable interface with the positive electrode/negative electrode, and the interface is not degraded along with deposition/stripping of lithium during the battery cycle. The thin film material provided by the embodiment of the application has the function of stabilizing lithium deposition/stripping.

Polyethylene glycol dimethacrylate in the film material can undergo a crosslinking reaction, so that the film material is converted into a film/crosslinking system with certain toughness. The film layer/crosslinking system can be applied to a lithium ion battery to play a role in inhibiting the growth of lithium dendrites.

With reference to the first implementation manner of the first aspect, the film layer material may further include: ethylene glycol monomethyl ether methacrylate.

According to the implementation mode, the ethylene glycol monomethyl ether methacrylate can be used as a terminal group of polyethylene glycol dimethacrylate capable of undergoing a crosslinking reaction, plays a role in stopping the polyethylene glycol dimethacrylate crosslinking reaction, and can control the relative molecular weight of a crosslinking system formed after crosslinking of the film material by controlling the content of the polyethylene glycol dimethacrylate and the polyethylene glycol monomethyl ether methacrylate.

With reference to the second implementation manner of the first aspect, a molar ratio of polyethylene glycol dimethacrylate (PEGDMA) to polyethylene glycol monomethyl ether methacrylate (PEGMA) is between 1:10 and 10:1.

In this implementation, the molar ratio of PEGDMA to PEGMA may be greater than or equal to 1:10. the molar ratio of PEGDMA to PEGMA is less than 1: compared with the implementation mode of 10, the membrane layer material provided by the implementation mode contains more PEGDMA, and more PEGDMA can be crosslinked to obtain a crosslinking system with a loose structure. Therefore, the film material provided by the implementation mode has a loose crosslinking system after being crosslinked, and the crosslinked film material has larger Li ⁺ conductivity.

The molar ratio of PEGDMA to PEGMA may be less than or equal to 10:1. The molar ratio of PEGDMA to PEGMA is more than 10: compared with the implementation mode of the film material, the implementation mode provided by the implementation mode contains more PEGMA, and the PEGMA can be used as a terminal group in the process of the crosslinking reaction of the film material so as to terminate the crosslinking reaction. The implementation mode can reduce the problem of local crystallization caused by the formation of a crosslinking system with larger crosslinking degree in the crosslinking process.

The molar ratio of PEGDMA to PEGMA is 1: the method can achieve the effects that the film material has larger Li ⁺ conductivity and reduces the local crystallization problem of the crosslinked film material between 10 and 10:1.

With reference to the third implementation manner of the first aspect, the molecular structure of the sulfonamide compound is an asymmetric structure.

In the implementation mode, the molecular structure of the sulfonamide compound is an asymmetric structure. The sulfonamide compound with an asymmetric molecular structure is not easy to generate close intermolecular stacking, and has larger plasticizing performance.

With reference to the fourth implementation manner of the first aspect, the substituent of the sulfonamide compound includes: methyl, ethyl or ether groups.

In this implementation, the substituents of the sulfonamide compound include: methyl, ethyl or ether groups. The sulfonamide compound containing methyl, ethyl or ether group substituent groups is not easy to crystallize, so that the sulfonamide compound is ensured to have larger plasticizing performance.

With reference to the fifth implementation manner of the first aspect, the lithium salt includes: lithium bis (fluorosulfonyl) imide and lithium bis (trifluoromethyl) sulfonyl imide.

In this embodiment, the lithium salt includes: lithium bis (fluorosulfonyl) imide and lithium bis (trifluoromethyl) sulfonyl imide. Both lithium bis (trifluoromethylsulfonyl) imide and lithium bis (trifluoromethylsulfonyl) imide have fluoride ions (F ^-),F^- can react with lithium metal in the negative electrode during charge and discharge, forming a lithium fluoride-containing SEI on the surface of the negative electrode, which can allow uniform deposition of Li ⁺ in the negative electrode or uniform exfoliation of Li in the negative electrode.

The lithium bis (fluorosulfonyl) imide has larger solubility in the polyethylene oxide polymer, so as to ensure that more lithium ions can be contained in the film material, and the polyethylene oxide polymer comprises: polyethylene glycol dimethacrylate, or include polyethylene glycol dimethacrylate and ethylene glycol monomethyl ether methacrylate.

With reference to the sixth implementation manner of the first aspect, a mass ratio of lithium bis (fluoro sulfonyl imide) (LiFSI) to lithium bis (trifluoromethyl) sulfonyl imide (LiTFSI) is between 1:2 and 2:1.

In this implementation, the mass ratio of LiTFSI to LiFSI may be less than or equal to 2:1. Compared with the implementation mode that the mass ratio of LiTFSI to LiFeSI is greater than 2:1, the film material provided by the implementation mode contains more LiFeSI, namely more Li ⁺ is dissolved in the polyethylene oxide polymer, and the film material has larger Li ⁺ conductivity.

The mass ratio of LiTFSI to LiFSI may be greater than or equal to 1:2. Compared with an implementation mode that the mass ratio of LiTFSI to LiFSI is smaller than 12, the film material provided by the implementation mode contains more LiTFSI. That is, more F ^- is dissolved in the polyethylene oxide polymer, and more LiF-containing SEI can be formed when the film material is applied to a lithium ion battery. The polyoxyethylene-based polymer includes: polyethylene glycol dimethacrylate, or include polyethylene glycol dimethacrylate and ethylene glycol monomethyl ether methacrylate. The mass ratio of LiTFSI to LiFSI can be 1:2-2:1, and the Li ⁺ conductivity of the film material and the F ^- content in the film material can be realized.

With reference to the seventh implementation manner of the first aspect, the mass fraction of the sulfonamide compound is 40% -60%. In the implementation mode, the mass fraction of the sulfonamide compound in the film material can be more than or equal to 40%. Compared with a film material with the mass fraction of the sulfonamide compound being less than 40%, the film material provided by the implementation mode contains more sulfonamide compounds, the plasticizing performance of the more sulfonamide compounds on the polyethylene oxide polymer is more remarkable, and further the polyethylene oxide polymer has larger chain segment movement, and correspondingly, the film material has larger Li+ conductivity. The polyoxyethylene-based polymer includes: polyethylene glycol dimethacrylate, or include polyethylene glycol dimethacrylate and ethylene glycol monomethyl ether methacrylate.

The mass fraction of the sulfonamide compound in the film material can be less than or equal to 60%. Compared with the film material with the mass fraction of the sulfonamide compound being more than 60%, the film material provided by the implementation mode contains less sulfonamide compound. The film material has higher viscosity due to fewer sulfonamide compounds, and the difficulty of coating the film material on the surface of the solid electrolyte is lower in the forming process of the lithium ion battery.

The mass fraction of the sulfonamide compound can be 40% -60%, and the viscosity of the film material and the Li+ conductivity of the film material can be considered.

With reference to the eighth implementation manner of the first aspect, the relative molecular weight of polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate is 300-600.

In this implementation, the relative molecular mass of polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate may be greater than or equal to 300. Compared with the implementation mode of using polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate with the relative molecular mass smaller than 300, the film material in the implementation mode adopts polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate with larger relative molecular mass. The crosslinking system formed after crosslinking of the film material provided by the implementation mode has larger toughness, and can generate stronger inhibition effect on lithium dendrites when being applied to a lithium ion battery.

The relative molecular mass of the polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate is less than or equal to 600. Compared with the implementation mode of using polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate with the relative molecular mass being more than 600, the film material in the implementation mode adopts polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate with smaller relative molecular mass. The film material provided by the implementation mode has larger fluidity, and the technical difficulty of the combination of the film material and the lithium ion battery liquid injection process is smaller.

The relative molecular mass of the polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate can be between 300 and 600, and the fluidity of the film material and the toughness of a crosslinked system formed after crosslinking can be considered.

With reference to the ninth implementation manner of the first aspect, the polymerization degree of polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate is between 4 and 12.

In this implementation, the degree of polymerization of polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate may be greater than or equal to 4. Compared with the implementation mode of polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate with the polymerization degree smaller than 4, the membrane layer material in the implementation mode adopts polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate with the higher polymerization degree, the cross-linking system formed after the polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate with the higher polymerization degree is cross-linked is loose in structure, the segment movement of the cross-linking system is more obvious, and the Li+ conductivity of the cross-linking system is higher.

The degree of polymerization of the polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate may be less than or equal to 12. Compared with the implementation mode of polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate with the polymerization degree larger than 12, the membrane layer material in the implementation mode adopts polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate with smaller polymerization degree, and the membrane layer material provided by the implementation mode has larger fluidity and smaller technical difficulty in combination of the membrane layer material and the lithium ion battery liquid injection process.

The polymerization degree of the polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate can be between 4 and 12, and the fluidity of the film material and the Li+ conductivity of the crosslinked film material can be both considered.

With reference to the tenth implementation manner of the first aspect, a molar ratio of ether bond contained in the polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate to lithium ion contained in the lithium salt is 10 to 30.

In this implementation, the molar ratio of ether linkages in the film material to li+ may be greater than or equal to 10. Compared with the implementation mode that the mole ratio of ether bonds to Li+ in the film material is smaller than 10, the film material provided by the implementation mode contains more ether bonds, and the film material has larger Li+ conductivity due to more ether bonds.

The molar ratio of ether linkages to li+ in the film material may be less than or equal to 30. Compared with the implementation mode that the mole ratio of ether bond to Li+ in the film material is larger than 30, the film material provided by the implementation mode contains fewer ether bonds, namely the relative molecular mass of polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate or the polymerization degree of polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate in the film material is smaller. Correspondingly, the viscosity of the film material provided by the implementation mode is low, and the technical difficulty of the combination of the film material and the lithium ion battery liquid injection process is low.

As a feasible implementation mode, the molar ratio of ether bond to Li+ in the film material can be 10-30, and the viscosity of the film material and the Li+ conductivity of the film material can be considered.

With reference to the eleventh implementation manner of the first aspect, the concentration of the lithium salt is less than or equal to 25%.

According to the implementation mode, the plasticizing effect of the sulfonamide compound on the polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate is achieved, so that the chain segment movement of the polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate is effectively promoted, and the migration performance of Li+ in the polyethylene glycol dimethacrylate/ethylene glycol monomethyl ether methacrylate is improved. Therefore, the mass fraction of the lithium salt adopted by the film material provided by the embodiment of the application can be less than or equal to 25%, and the film material can also have larger Li+ conductivity.

With reference to the twelfth implementation manner of the first aspect, the film layer material has fluidity.

According to the implementation mode, the film material has fluidity, so that the film material can be used together with a lithium ion battery liquid injection process.

With reference to the thirteenth implementation manner of the first aspect, the film layer material further includes: a separator material.

In this implementation, the membrane layer material also includes a membrane material that has the effect of allowing Li+ to pass through, isolating e-. Thus, the film material also has the effect of allowing Li+ to pass through, isolating e-.

In a second aspect of the embodiment of the present application, a film layer is provided, where the film layer is made of the film layer material provided in the first aspect.

The effect achieved by any implementation manner of the second aspect may refer to the effect achieved by any possible implementation manner of the first aspect.

With reference to the first implementation manner of the second aspect, the film layer has self-supporting properties.

According to the implementation mode, the film layer has self-supporting performance, and the film layer is applied between the positive electrode and the negative electrode of the lithium ion battery, so that the problem of conduction between the positive electrode and the negative electrode of the lithium ion battery caused by the occurrence of folds of the film layer can be solved.

A third aspect of an embodiment of the present application provides a lithium ion battery, including: the positive electrode, the negative electrode and the composite solid electrolyte are arranged between the positive electrode and the negative electrode, and the composite solid electrolyte adopts the film material provided by the thirteenth implementation manner of the first aspect.

In this implementation, the composite solid electrolyte adopts the membranous layer material, include: polyethylene glycol dimethacrylate, sulfonamide compound, lithium salt and diaphragm material.

The composite solid electrolyte adopts a film material, wherein the film material comprises: the separator material has the function of allowing lithium ions to pass through and blocking electrons, so that the composite solid electrolyte also has the function of allowing lithium ions to pass through and blocking electrons.

The sulfonamide compound can be used as a polyethylene glycol dimethacrylate dispersing agent, so that the sulfonamide compound, lithium salt and film material can form a uniform system. The film material provided by the implementation mode does not need to adopt a small molecular solvent, so that the problem caused by the residual small molecular solvent does not exist.

The sulfonamide compound can also be used as a plasticizer of polyethylene glycol dimethacrylate, intermolecular acting force exists between the sulfonamide compound and ether bond in the polyethylene glycol dimethacrylate, and the intermolecular acting force can be used for the glass transition temperature of the polyethylene glycol dimethacrylate, so that the segment movement of the polyethylene glycol dimethacrylate is effectively promoted, and the composite solid electrolyte has better Li+ conductivity.

The composite solid electrolyte has larger Li+ conductivity, and when the composite solid electrolyte is applied to a lithium ion battery, a serious charge layer is not formed between the composite solid electrolyte and the positive electrode/negative electrode. The composite solid electrolyte and the positive electrode/negative electrode can form a stable interface, and the interface is not degraded along with deposition/stripping of lithium in the battery cycle process, so that the lithium ion battery has stable cycle performance.

The composite solid electrolyte has certain toughness and can inhibit the growth of lithium dendrites on the surface of the cathode. Therefore, the lithium ion battery provided by the implementation mode can adopt the lithium metal negative electrode with higher specific capacity, so that the lithium ion battery is ensured to have higher energy density.

The negative electrode is in contact with the composite solid-state electrolyte. The composite solid electrolyte does not contain metals such as lanthanum and zirconium, and even if the negative electrode of the lithium ion battery adopts lithium metal, the side reaction between the composite solid electrolyte and the lithium metal is less. The composite solid electrolyte and the lithium metal negative electrode can still have a relatively stable interface after repeated charge and discharge cycles, and the lithium ion battery can still have relatively small interface impedance after repeated charge and discharge cycles.

A fourth aspect of an embodiment of the present application provides a lithium ion battery including: a positive electrode, a negative electrode, a solid electrolyte and at least one protective layer. A solid electrolyte is disposed between the positive electrode and the negative electrode; the protective layer is disposed between the solid electrolyte and the positive electrode and/or between the solid electrolyte and the negative electrode, and the protective layer is made of the film material provided in the first aspect.

In this realization side, the protective layer adopts the rete material, includes: polyethylene glycol dimethacrylate, sulfonamide compound and lithium salt.

The sulfonamide compound can be used as a polyethylene glycol dimethacrylate dispersing agent, so that the sulfonamide compound and the lithium salt can form a uniform system. The film material provided by the implementation mode does not need to adopt a small molecular solvent, so that the problem caused by the residual small molecular solvent does not exist.

The sulfonamide compound can also be used as a plasticizer of polyethylene glycol dimethacrylate, intermolecular acting force exists between the sulfonamide compound and ether bond in the polyethylene glycol dimethacrylate, and the intermolecular acting force can be used for the glass transition temperature of the polyethylene glycol dimethacrylate, so that the segment movement of the polyethylene glycol dimethacrylate is effectively promoted, and the protective layer has better Li+ conductivity.

The protective layer has larger Li+ conductivity, and when the protective layer is applied to a lithium ion battery, a serious charge layer is not formed between the protective layer and the positive electrode/negative electrode. The protective layer and the positive/negative electrode can form a stable interface, which is not degraded with deposition/stripping of lithium during the battery cycle, so that the lithium ion battery has stable cycle performance.

The protective layer has certain toughness and plays a role in inhibiting the growth of lithium dendrites. Thus, the protective layer may function to protect the solid electrolyte. The lithium ion battery provided by the implementation mode can adopt a lithium metal negative electrode with higher specific capacity, so that the lithium ion battery is ensured to have higher energy density.

The protective layer does not contain metals such as lanthanum and zirconium, and even if the negative electrode of the lithium ion battery adopts lithium metal, the protective layer and the lithium metal have fewer side reactions. The protective layer and the lithium metal cathode can still have a relatively stable interface after repeated charge and discharge cycles, and the lithium ion battery can still have relatively small interface impedance after repeated charge and discharge cycles.

A fifth aspect of the embodiment of the present application provides a method for preparing a lithium ion battery, including: adding an initiator into the film material provided in the first aspect to obtain a polymer precursor; forming a lithium ion battery by using the positive electrode, the negative electrode and the polymer precursor; the lithium ion battery includes: the positive electrode, negative electrode, and the compound solid electrolyte that sets up between positive electrode and negative electrode, compound solid electrolyte by the rete material forms.

With reference to the first implementation manner of the fifth aspect, the step of forming the lithium ion battery using the positive electrode, the negative electrode and the polymer precursor includes: treating the polymer precursor to form a composite solid electrolyte; and assembling the anode, the cathode and the composite solid electrolyte to obtain the lithium ion battery.

With reference to the second implementation manner of the fifth aspect, the step of forming the lithium ion battery using the positive electrode, the negative electrode and the polymer precursor includes: assembling the positive electrode, the negative electrode and the polymer precursor; the polymer precursor is treated such that the polymer precursor forms a composite solid electrolyte.

The effect of any implementation manner of the fifth aspect may refer to the effect of any possible implementation manner of the first aspect.

A sixth aspect of the embodiment of the present application provides a method for preparing a lithium ion battery, including: adding an initiator into the film material provided in the thirteenth implementation manner of the first aspect to obtain a polymer precursor; forming a lithium ion battery using the positive electrode, the negative electrode, the solid electrolyte and the polymer precursor, the lithium ion battery comprising: the positive electrode, the negative electrode, the solid electrolyte and at least one protective layer, wherein the solid electrolyte is arranged between the positive electrode and the negative electrode, the at least one protective layer is formed by a film layer material, and the protective layer is arranged between the solid electrolyte and the positive electrode and/or between the solid electrolyte and the negative electrode.

With reference to the first implementation manner of the sixth aspect, the step of forming the lithium ion battery using the positive electrode, the negative electrode and the solid electrolyte with the surface coated with the polymer precursor includes: coating a polymer precursor on the surface of the solid electrolyte; treating the polymer precursor such that the polymer precursor forms a protective layer; and assembling the anode, the cathode and the solid electrolyte with the protective layer on the surface to obtain the lithium ion battery.

With reference to the second implementation manner of the sixth aspect, the step of forming the lithium ion battery using the positive electrode, the negative electrode, the solid electrolyte and the polymer precursor includes: assembling a positive electrode, a negative electrode, a solid electrolyte and a polymer precursor; the polymer precursor is treated such that the polymer precursor forms a protective layer.

The effect achieved by any implementation manner of the sixth aspect may refer to the effect achieved by any possible implementation manner of the first aspect.

Drawings

FIG. 1 is a schematic diagram of a lithium ion battery;

FIG. 2 is a graph of the results of gram capacity and theoretical volumetric energy density achievable for a lithium ion battery anode material;

FIG. 3 is a graph of experimental results of the first prior art;

FIG. 4 is a graph of experimental results of the second prior art;

FIG. 5 is a graph of experimental results of the third prior art;

FIG. 6 is a graph of experimental results of the fourth prior art;

FIG. 7 is a schematic diagram of a film material according to an embodiment of the present application;

FIG. 8A is a structural formula of PEGMA;

FIG. 8B is a structural formula of PEGDMA;

FIG. 9 is a cross-linking system formed by PEGDMA and PEGMA provided by embodiments of the present application;

FIG. 10 shows the structural formula of sulfonamide compound according to the embodiment of the present application;

FIG. 11 is a schematic diagram of a lithium ion battery;

FIG. 12 is a graph of the results of a first lithium ion battery and a second lithium ion cycle performance test;

Fig. 13 is a graph of the cycle performance test results of a third lithium ion battery;

fig. 14 is an ionic conductivity versus temperature curve for a fourth lithium ion battery;

FIG. 15 is a schematic diagram of a passivation layer according to an embodiment of the present application;

FIG. 16 is a schematic illustration of a protective layer/composite solid state electrolyte provided in an embodiment of the present application;

FIG. 17 is a schematic view of a composite solid electrolyte provided in an embodiment of the present application;

Fig. 18 is a schematic diagram of a lithium ion battery according to an embodiment of the present application;

Fig. 19 is a graph of impedance test results of li|llzo|li and li|pe|llzo|pe|li;

FIG. 20 is a graph of the results of a Li|LLZO|Li cycle performance test;

FIG. 21 is a graph showing the results of a Li|PE|LLZO|PE|Li cycle performance test;

fig. 22 is a schematic diagram of a lithium ion battery according to an embodiment of the present application;

FIG. 23 is a graph showing the results of a Li|composite PE|Li cycle performance test;

FIG. 24 is a graph of the results of a Li|composite PE|Li cycle performance test;

Fig. 25 is a flowchart of a method for preparing an ion battery according to an embodiment of the present application;

FIG. 26 is a process flow diagram of the preparation method provided in FIG. 25;

FIG. 27 is a flow chart of the preparation of sulfonamide compounds according to the example of the present application;

fig. 28 is a cross-sectional view of a lithium ion battery according to an embodiment of the present application;

fig. 29 is a cross-sectional view of a battery cell according to an embodiment of the present application;

fig. 30 is a flowchart of a method for preparing an ion battery according to an embodiment of the present application;

FIG. 31 is a process flow diagram of the preparation method provided in FIG. 30;

fig. 32 is a cross-sectional view of a lithium ion battery according to an embodiment of the present application;

fig. 33 is a cross-sectional view of a battery cell according to an embodiment of the present application.

Detailed Description

The following description of the technical solutions according to the embodiments of the present application will be given with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments.

In the following, the terms "first," "second," and the like are used merely for descriptive purposes to distinguish between identical items or similar items that have substantially the same function and function, and are not to be construed as indicating or implying a relative importance or an implicit indication of the number of technical features indicated. Thus, a feature defining "a first", "a second", etc. may explicitly or implicitly include one or more such feature.

Also, in the description of the present application, unless otherwise indicated, "a plurality" means two or more than two.

Furthermore, in the present application, the terms of orientation such as "upper," "lower," "left," "right," "horizontal," and "vertical" are defined with respect to the orientation in which the components in the drawings are schematically disposed, and it should be understood that these directional terms are relative terms, which are used for descriptive and clarity with respect thereto, and which may be correspondingly altered in response to changes in the orientation in which the components in the drawings are disposed. The term "coupled" is to be interpreted broadly, unless explicitly stated or limited otherwise, such as for example: the connection can be fixed connection, detachable connection or integrated; can be directly connected or indirectly connected through an intermediate medium.

Meanwhile, in the embodiments of the present application, words such as "exemplary" or "such as" are used to mean serving as examples, illustrations or explanations. Any embodiment or design described herein as "exemplary" or "e.g." in an embodiment should not be taken as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion that may be readily understood.

First, concepts related to the embodiments of the present application will be described:

energy density (ENERGY DENSITY) is defined as the electrical energy stored per unit mass/volume of the lithium-ion battery.

Specific capacity (SPECIFIC CAPACITY), the amount of electricity that can be discharged per unit mass of lithium ion battery/positive electrode/negative electrode. The specific capacity is positively correlated with the energy density. Specific capacity may include areal capacity and gram capacity.

Segmental motion (SEGMENTAL MOTION), small-scale structural units such as chain segments, branched chains or side groups in macromolecules, internal rotation conformation changes and partial sub-motions.

The glass transition temperature (glass transition temperature, tg) refers to the temperature at which the glass transitions to a highly elastic state. Tg is the lowest temperature at which a molecular segment can move. With the continuous expansion of the electrochemical energy storage market and the power battery market, future application scenarios such as electric vehicles (ELECTRICAL VEHICLE, EV) and energy storage fields are continuously increasing in terms of performance of secondary batteries ((rechargeable battery).

Lithium ion battery (lithium ion cells and batteries) the lithium ion battery is a secondary battery which takes a lithium-containing compound as a positive electrode, and lithium ions (Li+) ionized by the positive electrode are stripped and deposited back and forth between the positive electrode and a negative electrode in the process of charging and discharging.

The room temperature is 20-30 ℃.

Low temperature, temperature less than 20 ℃. High temperature, the temperature is more than 30 ℃.

Referring to fig. 1, a lithium ion battery (lithium ion cells and batteries) includes: a positive electrode 11, a negative electrode 12 and an electrolyte 13. By the li+ back and forth peeling and deposition between the positive electrode 11 and the negative electrode 12, the lithium ion battery realizes charge/discharge.

The electrolyte 13 may include: a solid electrolyte or a liquid electrolyte. The organic electrode liquid is a commonly used liquid electrolyte.

The organic electrolyte may include: high purity organic solvent, electrolyte lithium salt. Among these, the electrolyte lithium salt may be, but is not limited to, lithium hexafluorophosphate (LiPF ₆), lithium tetrafluoroborate (LiBF ₄), or the like.

A ternary positive electrode material or lithium iron phosphate (LiFePO ₄) positive electrode |organic electrolyte| graphite negative electrode is a relatively mature lithium ion battery. The energy density of the lithium ion battery can reach 280 Wh/kg-300 Wh/kg. Wherein the ternary positive electrode material may be, but is not limited to: lithium cobalt oxide (LiCoO ₂) lithium nickel cobalt manganese oxide (LiNi _xCo_yMn_1-x-yO₂).

Lithium ion batteries employing organic electrolyte may be referred to as organic electrolyte system lithium ion batteries. The energy density of the existing organic electrolyte system lithium ion battery is close to the limit, and the bottleneck is difficult to break through.

On the one hand, the materials adopted by the positive electrode and the materials adopted by the negative electrode almost reach the limit of the respective theoretical specific capacities. On the other hand, the safety performance of the lithium ion battery is reduced with the selection of materials with high activity and high specific capacity for the positive electrode/negative electrode.

In order to adapt to different application scenes, the energy density of the lithium ion battery needs to be further improved. For example: taking the application scene of the electric airplane as an example, the energy density of the battery needs to reach more than 400 Wh/kg.

The material adopted by the cathode can be further improved so as to further improve the energy density of the lithium ion battery.

Lithium metal has extremely high specific capacity (the specific capacity of the lithium metal can reach 3860 mAh/g) and low oxidation-reduction potential (the reduction potential of the lithium metal can reach-3.04 Vvs). The negative electrode of the lithium ion battery adopts lithium metal, so that the energy density of the lithium ion battery can be greatly improved. Fig. 2 is a graph of the gram capacity and the theoretical volumetric energy density achievable for a lithium ion battery anode material.

It can be seen that a negative electrode of graphite was used: the gram capacity can reach 680Wh/L, and the theoretical volume energy density can reach 360mAh/g. Negative electrode using graphite and 15% silicon oxide (SiOx): the gram capacity can reach 800Wh/L, and the theoretical volume energy density can reach 600mAh/g. A negative electrode of silicon: the gram capacity can reach 1005Wh/L, and the theoretical volume energy density can reach 2000mAh/g. Negative electrode using lithium metal: the gram capacity can reach 1000Wh/L, and the theoretical volume energy density can reach 3000mAh/g.

Since lithium metal has high chemical activity, it is also necessary to overcome more problems when the lithium metal is used as a material of a negative electrode in a system of a specific lithium ion battery. In the embodiment of the application, the negative electrode adopting lithium metal can be called as a lithium metal negative electrode.

For example: the lithium ion battery has low coulombic efficiency due to the fact that the lithium metal has active chemical property and is easy to generate side reaction when being contacted with electrolyte. Coulombic efficiency, defined as the ratio of the discharge capacity of a lithium ion battery to the charge capacity during the same cycle.

With continued reference to fig. 1, for example: in a lithium ion battery using an organic electrolytic solution as an electrolyte, a separator 14 is required to be provided between the positive electrode 11 and the negative electrode 12. The separator 14 plays a role of isolating e ^-, so as to ensure electrical isolation between the positive electrode and the negative electrode.

Li ⁺ in the lithium metal anode 12 may combine with e ^- to form lithium atoms (Li) during the charge and discharge of the lithium ion battery. As the amount of Li increases, lithium dendrites (lithium dendrites) grow on the surface of the lithium metal anode 12. Wherein the lithium dendrite is dendritic lithium metal. The lithium dendrite growth breaks through the separator 14, which causes the positive electrode 11 to conduct with the lithium metal negative electrode 12, and the lithium ion battery is shorted. Therefore, the lithium metal cathode/organic electrolyte system lithium ion battery has potential safety hazard.

One possible method to apply lithium metal negative electrodes to lithium ion battery systems while solving battery safety performance once and for all is: an all-solid-state lithium ion battery is formed by replacing the organic electrolyte with a solid-state electrolyte (solid electrolyte electrode, SSE).

The solid electrolyte replaces organic electrolyte, so that the problem of safety of the lithium ion battery can be solved, but the problem of poor contact of a solid-solid interface (an interface between a lithium metal anode and the solid electrolyte) is also introduced. Particularly, in the process of lithium ion circulation, the problem of poor contact of a solid-solid interface is continuously aggravated along with the reciprocating process of stripping and depositing lithium on the surfaces of the lithium metal cathode and the solid electrolyte.

In addition, the solid electrolyte cannot fundamentally prevent the growth of lithium dendrites, and the lithium dendrites may penetrate through the solid electrolyte to conduct the positive electrode 11 and the lithium metal negative electrode 12, so that a short circuit occurs in the lithium ion battery.

Illustrating: garnet-type lithium lanthanum zirconium oxide ceramic oxide solid electrolyte material (Li ₇La₃Zr₂O₁₂ GARNET TYPE CERAMIC, LLZO) is a commonly used solid electrolyte material. When LLZO is used as the solid electrolyte, the relative density (RELATIVE DENSITY) of LLZO is compacted to 98%, and lithium dendrites are still able to penetrate the solid electrolyte.

The prior art discloses some implementation schemes for inhibiting lithium dendrites from affecting a lithium ion battery, and the following description is made with reference to specific drawings on a manner of inhibiting the influence of few lithium dendrites on the lithium ion battery:

The first prior art is:

The first prior art discloses a film material which can be used as a material of a protective layer and applied to a lithium ion battery. The protective layer is in contact with the lithium metal negative electrode, so that lithium dendrite formation on the surface of the lithium metal negative electrode can be inhibited, and the effect of protecting the solid electrolyte is achieved.

Referring to fig. 3, fig. 3 (a) shows a scanning electron microscope (scanning electron microscope, SEM) with a 3 μm scale of a portion of the negative electrode 31, the protective layer 32 and the solid electrolyte layer 33 in the lithium ion battery. Fig. 3 (two) shows an SEM of the protective layer and the solid electrolyte layer portions of the lithium ion battery disclosed in the first prior art on a scale of 1 μm. Wherein, the protective layer adopts a film layer material disclosed in the prior art. The protective layer 32 functions to protect the solid electrolyte layer 33 to reduce damage to the solid electrolyte layer 33 by nearby lithium dendrites.

As can be seen in fig. 3 (one) and fig. 3 (two), the protective layer 32 is located between the anode 31 and the solid electrolyte layer 33. Wherein the protective layer 32 is a polyethylene oxide/polyethylene glycol (polyoxyethylene, PEO) -PAS copolymer.

Wherein, the chemical formula of PAS can be referred to as (III) in FIG. 3. From fig. 3 (III), it can be seen that the PAS itself has a side chain with a sulfonic acid group 34, the sulfonic acid group 34 can be combined with Li ⁺, and no additional lithium salt or plasticizer is added into the material used for the protective layer.

Please refer to (fourth) in fig. 3. Fig. 3 (four) is an ion conductivity (conductivity)/lithium ion transfer number (transfer number) -temperature (temperature) curve of the protective layer; it can be seen that the ionic conductivity of the protective layer can reach 10 ^-6 S/cm at room temperature.

The film material disclosed in the first prior art has the following problems:

(1) The formation of the protective layer requires dispersing PEO and PAS in a separate addition of a graphic solvent. And removing the small molecule solvent by a heating treatment mode after the protective layer is formed. The process is easy to leave small molecule solvent. The residual small molecule solvent can have an effect on the lithium ion cycle performance.

(2) The protective film formed by the film material provided in the first prior art is applied to a lithium ion battery, and the interface impedance between the lithium metal cathode 31 and the protective layer 32 and the solid electrolyte layer 33 is larger, which can reach 600 Ω cm ².

(3) PAS monomer synthesis difficulty is high, and precursor cost is high.

And the second prior art is as follows:

In the second prior art, a film material is disclosed, which can be used as a material of a solid electrolyte interface (solid electrolyte interface, SEI) and applied to a lithium ion battery. The SEI contacts with the lithium metal cathode, can inhibit lithium dendrite formation on the surface of the lithium metal cathode, and plays a role in protecting the diaphragm.

Referring to fig. 4 (one) and fig. 4 (two), fig. 4 (one) is a schematic diagram of lithium metal negative electrode 41, sei42 and liquid electrolyte 43 in a lithium ion battery.

The second in fig. 4 is a scanning electron microscope image of the film layer material employed by the SEI42 in fig. 4. Wherein, (A) SEM of the film material under a scale of 100 nm. (B) SEM of the film material under a 50nm scale. (C) SEM (top view) of the film material under a2 μm scale. (D) SEM of the cross section of the film material under a2 μm scale.

It can be seen that the film layer material comprises: a polyvinylidene fluoride (PVDF) matrix 421 and mesoporous silicon 422. The mesoporous silicon 422 can improve the Young's modulus of the PVDF matrix 421, so that the SEI42 has higher toughness, and the SEI42 can well inhibit the growth of lithium dendrites.

Li ⁺ can be deposited at lithium metal anode 41 through the mesopores of mesoporous silicon 422. In particular, reference may be made to fig. 4 (three) and fig. 4 (four). Fig. 4 (iii) is a schematic diagram of a lithium ion battery, in which SEI of the lithium ion battery adopts a film layer material disclosed in the second prior art. Li ⁺ can be deposited at lithium metal anode 41 through SEI 42.

Specifically, reference may be made to fig. 4 (four), which is a schematic diagram of a film material in fig. 4. It can be seen that the mesopores of the mesoporous silicon 422 are larger than the particle size of Li ⁺, and Li ⁺ can be deposited to the lithium metal anode 31 through the mesopores of the mesoporous silicon 422.

The film material disclosed in the prior art has the following problems:

(1) The second prior art discloses a film material as SEI that requires a liquid electrolyte 43 in combination with a high concentration of lithium salt.

(2) The film material needs to be coated on the surface of the lithium metal anode 41. The process is suitable for laboratory research on the buckling layer and is difficult to apply to the soft-package battery core.

The third prior art is:

the third prior art discloses a solid electrolyte.

Referring to fig. 5 (a), fig. 5 (a) is a schematic diagram of a lithium ion battery. The ion battery adopts a solid electrolyte disclosed in the third prior art. As can be seen, the lithium ion battery includes: a positive electrode 51, a solid electrolyte 52, and a negative electrode 53.

Referring to fig. 5 (two), fig. 5 (two) is a schematic diagram of a solid electrolyte. Among them, polyethylene glycol monomethyl ether methacrylate (poly (ethylene glycol) methacrylate, PEGMA) 521 and bis (trifluoromethyl) sulfonimide (Lithium bis (trifluoromothanesulfonyl) imide, liTFSI) 522 are used as the solid electrolyte 52.

Referring to fig. 5 (iii), fig. 5 (iii) is a schematic diagram of the solid electrolyte synthesis process of fig. 5 (ii). The formation process of the solid electrolyte 52 is: PEGMA521 and LiTFSI522 are dispersed in Dimethylsulfoxide (DMSO) and crosslinked in situ to form solid electrolyte 52 using azobisisobutyronitrile (Azobisisobutyronitrile, AIBN) as an initiator.

The polymer provided in the third prior art has the following problems:

(1) The solid electrolyte 52 has a lithium ion conductivity of 2.7X10 ^-5 S/cm at room temperature (20 ℃ C. To 30 ℃ C.).

(2) The high concentration LISTFSI employed for solid electrolyte 52 increases the cost of solid electrolyte 52 and requires the addition of additional DMSO dispersant to form a homogeneous solution, which can affect the cycling performance of the lithium ion battery.

The prior art is four:

The fourth prior art discloses a polymer electrolyte membrane. The morphology of the polymer electrolyte membrane can be seen in fig. 6 (a). It can be seen that the polymer electrolyte membrane is in the form of a thin film. The polymer electrolyte membrane is obtained by crosslinking a polyethylene glycol diacrylate (PEGDA), liTFSI or lithium dioxalate borate (LiBOB) system and Succinonitrile (SN).

And (two) in fig. 6 is a lithium ion conductance-temperature curve of the polymer electrolyte membrane. It can be seen that the lithium ion conductance of the polymer electrolyte membrane can reach 0.76mS/cm at room temperature.

The polymer electrolyte membrane provided by the fourth prior art is used as a solid electrolyte to be applied to a lithium ion battery (the anode of the lithium ion battery adopts nickel cobalt aluminum oxide). The cycle performance of the lithium ion battery is tested, and the obtained experimental result can be referred to as (III) in fig. 6, so that the lithium ion battery has better cycle performance.

The polymer electrolyte membrane provided in the fourth prior art has the following problems:

(1) The polymer electrolyte membrane adopts SN as a plasticizer, and the plasticizer is easy to form plasticizing crystals at low temperature or under stress, so that the physical properties of the system are changed.

(2) The polymer electrolyte membrane has a soft texture, low mechanical strength, and is difficult to self-support. In particular, referring to fig. 6 (one), it can be seen that the polymer electrolyte membrane is softer and mechanically less strong, and is more difficult to self-support.

(3) The polymer electrolyte membrane adopts PEGDA, and when the molecular mass of the PEGDA is too high or the polymerization degree is too high, the local crystallization of the crosslinking system can show brittleness.

The existing electrolyte mostly adopts high molecular weight polymer, the dispersion performance of the high molecular weight polymer is poor, a small molecular solvent is needed to be added for dispersion, the existence of the small molecular solvent can have adverse effect on the cycle performance of the lithium ion battery, and the Li ⁺ conductivity of the high molecular weight polymer is low.

In order to solve the technical problems in the prior art, the embodiment of the application provides a film material. The film material can be used as a protective layer between lithium metal and solid electrolyte. Referring to fig. 7, the film material includes: lithium salt 71, polyethylene glycol dimethacrylate 72 and sulfonamide compound 73.

Wherein a lithium salt is used to provide Li ⁺. Polyethylene glycol dimethacrylate 72 serves as a matrix for the film material, and polyethylene glycol dimethacrylate 72 contains ether linkages (C-O-C), each of which can be referred to as a site. The polyethylene glycol dimethacrylate 72 molecules have chain segment movement, and the chain segment movement can drive the displacement of Li ⁺ among different sites, so that the migration of Li ⁺ is realized.

In the implementation manner, the sulfonamide compound 73 can be used as a polyethylene glycol dimethacrylate 72 dispersing agent, so that the sulfonamide compound 73, the polyethylene glycol dimethacrylate 72 and the lithium salt 71 can form a uniform system. The film material provided by the implementation mode does not need to adopt a small molecular solvent, so that the problem caused by the residual small molecular solvent does not exist.

Intermolecular acting force exists between the sulfonamide compound 73 and ether bond in the polyethylene glycol dimethacrylate 72, and the intermolecular acting force can reduce the glass transition temperature of the polyethylene glycol dimethacrylate 72, so that the chain segment movement of the polyethylene glycol dimethacrylate 72 is effectively promoted, and the Li ⁺ conductivity of the film material is further improved. Because the glass transition temperature of the polyethylene glycol dimethacrylate 72 is reduced, the film material provided by the embodiment of the application can show larger Li ⁺ conductivity at room temperature, low temperature and high temperature.

The film material has larger Li ⁺ conductivity, and when the film material is applied to a lithium ion battery, a serious charge layer is not formed between the film formed by the film material and the positive electrode/negative electrode of lithium ions. The film layer formed by the film layer material can form a stable interface with the positive electrode/negative electrode, and the interface is not degraded along with deposition/stripping of lithium during the battery cycle. The thin film material provided by the embodiment of the application has the function of stabilizing lithium deposition/stripping.

The film material can undergo a crosslinking reaction, and a crosslinked system (film) obtained after crosslinking has certain toughness and can inhibit the growth of lithium dendrites.

As a feasible implementation mode, the film material has fluidity, so that the film material can be used together with a lithium ion battery liquid injection process.

The following further describes the components of the film material provided in the embodiments of the present application:

the film layer material comprises: a lithium salt 71.

In an embodiment of the present application, lithium salt 71 is used to provide Li ⁺.

The lithium salt 71 may include: one or a mixture of several of lithium dioxalate borate (LiBOB), lithium perchlorate (LiClO ₄), lithium hexafluorophosphate (LiPF ₆) and lithium imide (LiFNFSI).

As a possible implementation, the lithium salt 71 may further include: lithium bis (trifluoromethyl) sulfonimide (Lithiumbis (trifluoromothanesulfonyl) imide, liTFSI). LiTFSI contains fluoride ions (F ^-).

F ^- can react with lithium metal (Li) in the anode during charge and discharge, forming a lithium fluoride (LiF) -containing SEI on the anode surface. The SEI containing LiF can allow uniform deposition of Li ⁺ to the anode or uniform exfoliation of Li in the anode.

It is considered that the Li ⁺ conductivity of the film material is positively correlated with the content of Li ⁺ in the film material. The greater the content of Li ⁺ in the film material, the greater the lithium ion conductivity of the film material; the smaller the content of Li ⁺ in the film material, the smaller the lithium ion conductivity of the film material.

Because of the relatively low solubility of LiTFSI in polyethylene glycol dimethacrylate 72, the Li ⁺ content of LiTFSI film materials is limited if only lithium salts are included.

In order to ensure the content of Li ⁺ in the film material. As one possible implementation, the lithium salt may include: liTFSI and lithium bis (fluorosulfonyl) imide (Lithium bis (fluorosulfonyl) imide, liFSI). Wherein, the solubility of LiFSI in polyethylene glycol dimethacrylate 72 is greater than the solubility of LiTFSI in polyethylene glycol dimethacrylate 72. Thus, the lithium salt 71 in this embodiment includes: liTFSI and LiFSI can ensure the Li ⁺ content of the film material.

On the premise that the mass of the lithium salt 71 is constant, the larger the mass of LiFeSI, the more Li ⁺ is dissolved in the polyethylene glycol dimethacrylate 72, the more Li ⁺ content in the finally obtained film material, and the larger the Li ⁺ conductivity of the film material.

As a viable implementation, the mass ratio of LiTFSI to LiFSI may be less than or equal to 2:1. Compared with the implementation mode that the mass ratio of LiTFSI to LiFSI is greater than 2:1, the film material provided by the implementation mode contains more LiFSI. That is, more Li ⁺ is dissolved in the polyethylene glycol dimethacrylate 72, and the film material has larger Li ⁺ conductivity.

On the premise of a certain lithium salt quality, the larger the LiTFSI quality is, the more F ^- is dissolved in polyethylene glycol dimethacrylate 72, and the more SEI containing LiF can be formed when the film material is applied to a lithium ion battery.

As a viable implementation, the mass ratio of LiTFSI to LiFSI may be greater than or equal to 1:2. Compared with an implementation mode that the mass ratio of LiTFSI to LiFSI is smaller than 12, the film material provided by the implementation mode contains more LiTFSI. That is, more F ^- is dissolved in the polyethylene glycol dimethacrylate 72, and more SEI containing LiF can be formed when the film material is applied to a lithium ion battery.

In order to achieve both the Li ⁺ conductivity of the film material and the F ^- content of the film material, as a feasible implementation manner, the mass ratio of LiTFSI to LiFSI may be 1:2-2:1.

In the embodiment of the application, the film layer material further comprises: polyethylene glycol dimethacrylate 72 (PEGDMA) DIMETHACRYLATE.

Polyethylene glycol dimethacrylate 72 contains ether linkages (C-O-C), each of which can be referred to as a site. Polyethylene glycol dimethacrylate 72 serves as a matrix for the film material. The polyethylene glycol dimethacrylate 72 molecules have chain segment movement, and the chain segment movement can drive the displacement of Li ⁺ among different sites, so that the migration of Li ⁺ is realized.

As a possible implementation, the film material may include: polyethylene glycol monomethyl ether methacrylate (poly (ethylene glycol) methacrylate, PEGMA) 74.

The structural formula of PEGMA may be referred to as fig. 8A. It can be seen that PEGMA has a site that binds Li ⁺. PEGMA also has a carbon-carbon double bond (c=c). PEGMA may act as an end group during the crosslinking reaction of the membrane material to terminate the crosslinking reaction.

The structural formula of PEGDMA can be seen in fig. 8B. It can be seen that PEGDMA has a site for binding Li ⁺, and PEGDMA also has two carbon-carbon double bonds. PEGDMA can be used as a chain element (CHAIN ELEMENT) in the cross-linking reaction process of the film material, and a cross-linking system is formed by using two carbon-carbon double bonds.

The cross-linking system formed by PEGDMA and PEGMA can be seen in fig. 9. It can be seen that PEGDMA acts as a mer of the crosslinking system and PEGMA acts as an end group of the crosslinking system.

As a possible implementation, the molar ratio of PEGDMA to PEGMA may be greater than or equal to 1:10. the molar ratio of PEGDMA to PEGMA is less than 1: compared with the implementation mode of 10, the membrane layer material provided by the implementation mode contains more PEGDMA, and more PEGDMA can be crosslinked to obtain a crosslinking system with a loose structure. Therefore, the film material provided by the implementation mode has a loose crosslinking system after being crosslinked, and the crosslinked film material has larger Li+ conductivity.

As a possible implementation, the molar ratio of PEGDMA to PEGMA may be less than or equal to 10:1. The molar ratio of PEGDMA to PEGMA is more than 10: compared with the implementation mode of the film material, the implementation mode provided by the implementation mode contains more PEGMA, and the PEGMA can be used as a terminal group in the process of the crosslinking reaction of the film material so as to terminate the crosslinking reaction. The implementation mode can reduce the problem of local crystallization caused by the formation of a crosslinking system with larger crosslinking degree in the crosslinking process. Therefore, the film material provided by the implementation manner can avoid the problem (3) in the fourth prior art.

In order to achieve both the Li+ conductivity of the crosslinked film material and the reduction of crystallization problems of the crosslinked film material, the molar ratio of PEGDMA to PEGMA can be 1:10-10:1 as a feasible implementation mode.

With continued reference to fig. 8A and 8B, PEGDMA and PEGMA may be referred to as polyethylene oxide based polymers. Examples of the present application, unless specifically stated otherwise, the polyoxyethylene-based polymer includes: polyethylene glycol dimethacrylate, or include polyethylene glycol dimethacrylate and ethylene glycol monomethyl ether methacrylate.

Considering that the more ether linkages in the film material, the more sites for li+ transfer, the better the li+ conductivity of the film material.

On the premise that the Li+ content of the film material is constant. As a possible implementation, the molar ratio of ether linkages in the film material to li+ may be greater than or equal to 10. Compared with the implementation mode that the mole ratio of ether bonds to Li+ in the film material is smaller than 10, the film material provided by the implementation mode contains more ether bonds, and the film material has larger Li+ conductivity due to more ether bonds.

The greater the relative molecular mass of the polyethylene oxide polymers (72, 74) in the film material, or the greater the degree of polymerization of the polyethylene oxide polymers (72, 74), the greater the viscosity of the corresponding film material, taking into account the greater the number of ether linkages in the film material. The greater the technical difficulty of combining the membrane layer material with the lithium ion battery liquid injection process.

On the premise that the Li+ content of the film material is constant. As a possible implementation, the molar ratio of ether linkages to li+ in the film material may be less than or equal to 30. Compared to implementations in which the molar ratio of ether linkages to li+ in the film layer material is greater than 30. The film material provided by the implementation manner contains fewer ether bonds, namely the relative molecular mass of the polyethylene oxide polymers (72, 74) in the film material is smaller, or the polymerization degree of the polyethylene oxide polymers (72, 74) is smaller. Correspondingly, the viscosity of the film material provided by the implementation mode is low, and the technical difficulty of the combination of the film material and the lithium ion battery liquid injection process is low.

In order to achieve both the viscosity of the film material and the li+ conductivity of the film material, as a feasible implementation manner, the molar ratio of the ether bond in the film material to li+ may be between 10 and 30.

The film material is applied to a lithium ion battery, and polyethylene oxide polymers (72, 74) in the film material can be crosslinked to obtain a crosslinking system (film). The crosslinking system has certain toughness and can inhibit the growth of lithium dendrites. The molecule of the crosslinking system has segment movement, and the segment movement can drive the displacement of Li+ among different sites, so that the migration of Li+ is realized.

The greater the degree of polymerization of the polyethylene oxide polymer (72, 74), the more relaxed the crosslinked architecture formed upon crosslinking of the polyethylene oxide polymer (72, 74) is considered. The more pronounced the segmental motion of the crosslinking system, the greater the li+ conductivity of the crosslinking system.

As one possible implementation, the degree of polymerization of the polyethylene oxide-based polymer (72, 74) is greater than or equal to 4. Compared with the implementation mode of using the polyethylene polymers (72, 74) with the polymerization degree smaller than 4, the film layer material in the implementation mode adopts the polyethylene polymers (72, 74) with the higher polymerization degree, the cross-linking system formed after the polyethylene polymers (72, 74) with the higher polymerization degree are cross-linked is loose in structure, the chain segment movement of the cross-linking system is more obvious, and the Li+ conductivity of the cross-linking system is higher. In the embodiment of the present application, the crosslinked system may also be referred to as a crosslinked film material or film.

Considering that the higher the polymerization degree of the polyethylene oxide polymers (72, 74), the lower the fluidity of the finally obtained film material, and the greater the technical difficulty of the combination of the film material and the lithium ion battery liquid injection process.

As a possible implementation, the degree of polymerization of the polyethylene oxide-based polymer (72, 74) may be less than or equal to 12. Compared with the implementation mode of adopting the polyethylene oxide polymer (72, 74) with the polymerization degree larger than 12, the film material in the implementation mode adopts the polyethylene oxide polymer (72, 74) with the smaller polymerization degree, has larger fluidity, and has smaller technical difficulty in combination of the film material and the lithium ion battery liquid injection process.

In order to achieve both the fluidity and the Li+ conductivity of the crosslinked film material. As a possible implementation, the degree of polymerization of the polyethylene oxide-based polymer (72, 74) may be in the range of 4 to 12.

The greater the relative molecular mass of the polyethylene oxide polymers (72, 74), the more ductile the crosslinked system formed after crosslinking the polyethylene oxide polymers (72, 74) is considered. The stronger the toughness of the crosslinking system, the stronger the inhibition of the crosslinking system to lithium dendrites.

As one possible implementation, the relative molecular mass of the polyethylene oxide-based polymer (72, 74) may be greater than or equal to 300. In this implementation, the film material is a polyethylene oxide polymer (72, 74) having a greater relative molecular mass than an implementation using a polyethylene oxide polymer (72, 74) having a relative molecular mass less than 300. The crosslinking system formed after crosslinking of the film material provided by the implementation mode has larger toughness, and can generate stronger inhibition effect on lithium dendrites when being applied to a lithium ion battery.

The fluidity of the polyethylene oxide polymer (72, 74) is smaller, considering that the larger the relative molecular mass of the polyethylene oxide polymer (72, 74) is, the lower the fluidity of the finally obtained film material is.

As one possible implementation, the relative molecular mass of the polyethylene oxide-based polymer (72, 74) is less than or equal to 600. In this implementation, the film material uses a polyethylene oxide polymer (72, 74) having a smaller relative molecular mass than an implementation using a polyethylene oxide polymer (72, 74) having a relative molecular mass greater than 600. The film material provided by the implementation mode has larger fluidity, and the technical difficulty of the combination of the film material and the lithium ion battery liquid injection process is smaller.

In order to achieve both the flowability of the film material and the toughness of the crosslinked system formed after crosslinking, the relative molecular mass of the polyethylene oxide-based polymers (72, 74) may be 300 to 600 as one possible implementation.

In the embodiment of the application, the film layer material further comprises: sulfonamide compound 73.

Referring to fig. 10, fig. 10 is a structural formula of a sulfonamide compound provided in a feasible implementation manner. It should be noted that fig. 10 is merely an exemplary illustration of a molecular structure of the sulfonamide compound 73 having an asymmetric structure, and the molecular structure is not limited thereto.

In fig. 10, R ₁、R₂、R₃、R₄ is a substituent of the sulfonamide compound 73. In the examples of the present application, the type of the substituent of the sulfonamide compound 73 is not particularly limited.

In order to prevent the plasticizing performance of the sulfonamide compound 73 from being lowered by crystallization, the substituent of the sulfonamide compound 73 may be a short-chain substituent as one of the possible implementation modes. Wherein the short chain substituents may be, but are not limited to: methyl, ethyl or ether groups.

As a possible implementation, the sulfonamide compound 73 has an asymmetric molecular structure.

In general, sulfonamide compounds having a symmetrical molecular structure are prone to close intermolecular stacking to form a local structure of plasticized crystals. Such plasticized crystal structures typically form at low temperatures or under stress. The formation of plasticized crystals reduces the plasticizing properties of the sulfonamide compound.

The sulfonamide compound 73 has an asymmetric molecular structure, compared with a sulfonamide compound having a symmetric molecular structure. The sulfonamide compound 73 having an asymmetric molecular structure is less likely to cause close intermolecular stacking, and the sulfonamide compound 73 is less likely to form a local structure of a plasticized crystal. Thus, the sulfonamide compound 73 has a large plasticizing property.

The plasticizing performance of the sulfonamide compound 73 is specifically expressed as: the intermolecular force exists between the sulfonamide compound 73 and ether bonds in the polyethylene oxide polymer (72, 74), and the intermolecular force can reduce the glass transition temperature of the polyethylene oxide polymer, so that the polyethylene oxide polymer (72, 74) has larger chain segment movement at low temperature and room temperature, and the film material has larger Li+ conductivity at room temperature and low temperature.

The problem (1) in the solution provided by the second prior art and the problem (2) in the solution provided by the third prior art indicate the need to use lithium salts in high concentrations. In the film material provided by the embodiment of the application, the plasticizing performance of the sulfonamide compound 73 on the polyethylene oxide polymers (72 and 74) can improve the migration performance of Li ⁺ in the polyethylene oxide polymers (72 and 74). Therefore, the mass fraction of the lithium salt adopted by the film material provided by the embodiment of the application can be less than or equal to 25%.

In the embodiment of the present application, the sulfonamide compound 73 also functions as a dispersant. Specifically, the sulfonamide compound 73 can mix the polyethylene oxide polymer (72, 74) and the lithium salt 71 to form a uniform solution. Compared with the problem (1) in the scheme provided by the first prior art and the problem (2) in the scheme provided by the third prior art. The film material provided by the embodiment of the application does not need to additionally introduce a small molecular dispersing agent. When the film material provided by the embodiment of the application is applied to a lithium ion battery, the problem that the cycle performance of the lithium ion battery is affected by residual small molecule solvents is avoided. Therefore, the film material provided by the embodiment of the application is applied to a lithium ion battery, and the lithium ion battery can have better cycle performance.

Considering that the larger the mass fraction of the sulfonamide compound 73 in the film material, the more remarkable the plasticizing performance of the sulfonamide compound 73 on the polyethylene oxide polymers (72, 74), the more remarkable the segment movement of the polyethylene oxide polymers (72, 74), and the larger the Li ⁺ conductivity of the film material.

As a possible implementation manner, the mass fraction of the sulfonamide compound 73 in the film material may be greater than or equal to 40%. Compared with the film material with the mass fraction of the sulfonamide compound 73 being less than 40%, the film material provided by the implementation mode contains more sulfonamide compounds 73, the plasticizing performance of the more sulfonamide compounds 73 on the polyethylene oxide polymers (72 and 74) is more remarkable, further the polyethylene oxide polymers (72 and 74) have better segment movement, and correspondingly, the film material has larger Li ⁺ conductivity.

Considering that the larger the mass fraction of the sulfonamide compound 73 in the film material is, the smaller the viscosity of the film material is, and the greater the difficulty of coating the film material on the surface of the solid electrolyte is in the formation process of the lithium ion battery.

As a possible implementation, the mass fraction of the sulfonamide compound 73 in the film material may be less than or equal to 60%. Compared with the film material with the mass fraction of the sulfonamide compound 73 being more than 60%, the film material provided by the implementation mode contains less sulfonamide compound 73. The film material has higher viscosity due to fewer sulfonamide compounds 73, and the difficulty of coating the film material on the surface of the solid electrolyte is lower in the forming process of the lithium ion battery.

In order to achieve both the viscosity of the film material and the Li ⁺ conductivity of the film material, the mass fraction of the sulfonamide compound 73 as a feasible implementation mode can be 40-60%.

The film layer material as a feasible implementation manner may further comprise: a separator material.

In embodiments where the membrane layer material comprises a membrane material, the material comprising lithium salt, polyethylene oxide based polymer (72, 74), sulfonamide compound may be referred to as a polymer material.

The separator material has the function of allowing Li ⁺ to pass through and isolating e ^-, so that the film layer containing the separator material has the function of allowing Li ⁺ to pass through and isolating e ^-. The separator material comprises: polypropylene (PP), celluloid or other porous lithium ion battery separator material.

The content of lithium salt in the material for preparing the solid electrolyte is 8-35%. Wherein, the material with lower lithium salt content has lower lithium ion conductivity. The sulfonamide compound in the film material provided by the embodiment of the application can be used as a plasticizer of polyethylene glycol dimethacrylate, intermolecular acting force exists between the sulfonamide compound and ether bond in the polyethylene glycol dimethacrylate, and the intermolecular acting force can be used for the glass transition temperature of the polyethylene glycol dimethacrylate, so that the segment movement of the polyethylene glycol dimethacrylate is effectively promoted, and the film material has better Li ⁺ conductivity. The lithium salt of the film material provided by the embodiment of the application can be controlled to be less than 25%, and the lithium ion conductivity of the film material can reach 6.2 multiplied by 10 ^-4 S/cm at room temperature.

At present, the disclosed material for preparing solid electrolyte is applied to a lithium ion battery, and the cycle performance test of the lithium ion battery needs to be carried out at high temperature.

The film material has larger Li ⁺ conductivity, and when the film material is applied to a lithium ion battery, a serious charge layer is not formed between the film formed by the film material and the positive electrode/negative electrode of lithium ions. The film layer and the positive/negative electrode can form a stable interface that does not deteriorate with deposition/stripping of lithium during battery cycling. The film material provided by the embodiment of the application has the effect of stabilizing lithium deposition/stripping, and the specific action mechanism is probably a three-dimensional lithium deposition site formed after the film material is crosslinked, so that the deposition of lithium metal is more uniform; another possible explanation is that fluorine in the lithium salt reacts with lithium metal during charge and discharge to form a LiF-rich SEI film on the surface of lithium metal, thereby achieving uniform deposition and exfoliation of lithium metal. So that the lithium ion battery has stable cycle performance. For example: the cycle was 1400 hours at a current density of 0.2mA/cm ².

The sulfonamide compound in the film material provided by the embodiment of the application can be used as a polyoxyethylene polymer dispersing agent, so that the sulfonamide compound, the polyoxyethylene polymer and the lithium salt can form a uniform system. The film material provided by the implementation mode does not need to adopt a small molecular solvent, so that the problem caused by the residual small molecular solvent does not exist.

In the film material provided by the embodiment of the application, the polyethylene oxide polymer can undergo a crosslinking reaction, so that the film material is converted into a solid film. The effects of the film material provided by the embodiment of the present application are described below with reference to specific examples:

in the first embodiment, the content of each component of the film material can be referred to in table 1.

TABLE 1

Component (A)	Mass fraction (%)
		PEGMA(Mn＝550g/mol)	6
PEGDMA(Mn＝500g/mol)	17
		Sulfonamide compounds (EMSA)	52
LiTFSI	15
		LiFSI	10

The comparative examples are: polyethylene glycol diacrylate (PEGDA) +30% lithium salt.

The crosslinked and polymerized product of the film material provided in the first example and the crosslinked and polymerized product of the comparative example were applied as solid electrolytes to the lithium ion battery provided in fig. 11, respectively.

For convenience of distinction, the lithium ion battery using the film material provided by the embodiment of the application is referred to as a first lithium ion battery, and the lithium ion battery using the comparative example is referred to as a second lithium ion battery.

The cycle performance of the first lithium ion battery and the second lithium ion battery at 70 ℃ and 200mAh/cm ² current density is tested, and the test result can be seen in fig. 12.

Fig. 12 (one) is a potential versus cycle time curve of the first lithium ion battery. The second in fig. 12 is a potential versus cycle time curve for the second lithium ion battery. It can be seen that the first lithium ion battery has better cycle performance. The second lithium ion cycle performance is poor.

The formation of the solid electrolyte in the second lithium ion battery requires the addition of a small molecule solvent or dispersant, which is removed after the formation of the solid electrolyte. Residual small molecule solvents or dispersants can have an impact on the cycling performance of lithium ion batteries.

The embodiment of the application provides a film material without adding a small molecular solvent or a dispersing agent, so that the film material does not need to additionally increase the solvent volatilization procedure after cross-linking polymerization, and small molecular solvent residues are avoided. Therefore, the solid electrolyte formed by the film material provided by the embodiment of the application is applied to a lithium ion battery, and the lithium ion battery can have better cycle performance.

The membrane material provided in the first embodiment was applied as a liquid electrolyte to the lithium ion battery provided in fig. 11, to obtain a third lithium ion battery.

The cycling performance of the third lithium ion battery at a current density of 0.05mAh/cm ² and a current density of 0.2mAh/cm ² was tested, and the test results can be seen in FIG. 13.

The potential versus cycle time curve for the third lithium ion battery at a current density of 0.05mAh/cm ² is shown in FIG. 13. The second in fig. 13 is a potential versus cycle time curve for a third lithium ion battery at a current density of 0.2mAh/cm ². It can be seen that the film material provided by the embodiment of the application is applied to a lithium ion battery as a liquid electrolyte, and the lithium ion battery can also have better cycle performance.

Embodiment two:

molar ratio of LiFSI to LiTFSI 1:1, a film layer obtained after crosslinking a film layer material with mole=20 of ether bond and lithium ion is used as a solid electrolyte in the lithium ion battery provided in fig. 11, so as to obtain a fourth lithium ion battery.

And testing the lithium ion migration number and the interface impedance of the fourth lithium ion battery. The test results can be seen in fig. 14. In FIG. 14, 70%, 30% and 50% are mass fractions of EMSA and PEGDA in the system composed of EMSA and PEGDA.

Fig. 14 (a) shows an ion conductivity-temperature curve of a fourth lithium ion battery. Fig. 14 (two) shows the interfacial impedance-temperature curve of the fourth lithium ion battery.

The room temperature lithium ion conductivity of the crosslinking system obtained by crosslinking PEGDA after adding EMSA is improved from 10 ^-6S/cm～10^-5 S/cm (without EMSA) to 10 ^-4 S/cm.

After the EMSA is added, the interface impedance between the solid electrolyte and the lithium metal anode is improved to a certain extent along with the increase of the EMSA content. Specifically, referring to fig. 14 (two), the interface impedance of a lithium ion battery of 70% emsa is smaller than that of a lithium ion battery of 50% emsa at 20 ℃ to 30 ℃.

The embodiment of the application also provides a film layer which is used for protecting the solid electrolyte. Referring to fig. 15, fig. 15 is a schematic view of a film layer according to an embodiment of the application. The film layer adopts the film layer material provided by the embodiment of the application, and the film layer material can comprise: lithium salts, polyoxyethylene polymers and sulfonamide compounds.

The film layer adopts the film layer material provided by the embodiment of the application, so that the film layer has the effect of the film layer material.

The film layer provided by the embodiment of the application can be used as a protective layer of solid electrolyte in a lithium ion battery, and the protective layer can be arranged between the anode and the solid electrolyte and/or between the cathode and the solid electrolyte of the lithium ion battery.

The solid electrolyte may be, but is not limited to, an oxide ceramic solid electrolyte material, a sulfide solid electrolyte material, and the like.

As a feasible implementation, the protection layer has self-supporting property, please refer to fig. 16. Fig. 16 is a schematic diagram of a passivation layer according to one possible embodiment. It can be seen that the protective layer 162 is clamped by the clamp 161, and the protective layer 162 can be independently supported, i.e., the protective layer 162 has self-supporting properties.

In this implementation manner, the protection layer 162 has self-supporting performance, the protection layer 162 is applied to the lithium ion battery, the protection layer 162 has self-supporting performance, and the protection layer 162 is not easy to wrinkle, so that the problem of conducting the positive electrode and the negative electrode of the lithium ion battery due to the wrinkling of the protection layer 162 can be reduced. The protection layer 162 provided in the embodiment of the present application can overcome the problem (2) in the fourth prior art.

The protective layer 162 is obtained by crosslinking the film layer material provided by the embodiment of the application, and has certain toughness. Therefore, the protective layer 162 may inhibit the growth of lithium dendrites, and thus may reduce the problem of a short circuit between the positive electrode and the negative electrode due to penetration of lithium dendrites through the solid electrolyte to some extent.

The embodiment of the application provides a lithium ion battery with a lithium metal negative electrode, wherein the protective layer does not contain metals such as lanthanum and zirconium, and side reactions between the protective layer and the lithium metal are less even if the lithium ion battery is applied to the lithium ion battery with the lithium metal negative electrode. The protective layer has larger Li ⁺ conductivity, a serious charge layer is not formed between the protective layer and the negative electrode, and a stable interface can be formed between the protective layer and the negative electrode, and the interface is not degraded along with deposition/stripping of lithium in the battery cycle process. After repeated charge and discharge cycles, the protective layer provided by the embodiment of the application can still have a relatively stable interface with the lithium metal anode. The lithium ion battery adopting the protective layer provided by the embodiment of the application can still have smaller interface impedance after repeated charge and discharge cycles.

The embodiment of the application also provides a film layer. Referring to fig. 17, fig. 17 is a schematic diagram of a film layer according to an embodiment of the application. The film layer adopts the film layer material provided by the embodiment of the application. The film layer material comprises: separator material, lithium salt, polyoxyethylene polymer and sulfonamide compound.

The film layer provided by the embodiment of the application can be used as a composite solid electrolyte and can be applied to a lithium ion battery. The composite solid state electrolyte may be disposed between a positive electrode and a negative electrode of the lithium ion battery. Compared with the solid electrolyte of LLZO, the embodiment of the application provides that the composite solid electrolyte does not contain metals such as lanthanum and zirconium, and even if the composite solid electrolyte is applied to a lithium ion battery adopting a lithium metal negative electrode, the composite solid electrolyte has fewer side reactions with lithium metal. The composite solid electrolyte has larger Li+ conductivity, a serious charge layer is not formed between the composite solid electrolyte and the positive electrode/negative electrode, and a stable interface can be formed between the composite solid electrolyte and the positive electrode/negative electrode, and the interface is not degraded along with deposition/stripping of lithium in the battery cycle process. After multiple charge and discharge cycles, the composite solid electrolyte provided by the embodiment of the application can still have a relatively stable interface with the anode/cathode. The lithium ion battery adopting the composite solid electrolyte provided by the embodiment of the application can still have smaller interface impedance after repeated charge and discharge cycles.

As a possible implementation, the composite solid electrolyte has self-supporting properties, see fig. 16. Fig. 16 is a schematic view of a composite solid electrolyte provided in one possible embodiment. It can be seen that the composite solid electrolyte 162 is held by the clip 161, and the composite solid electrolyte 162 can be supported independently, that is, the composite solid electrolyte 162 has self-supporting property. The film layer provided by the implementation manner can overcome the problem (2) in the fourth prior art.

In this implementation, the composite solid electrolyte has self-supporting properties, and is applied between the positive electrode and the negative electrode in a lithium ion battery. The compound solid electrolyte is not easy to wrinkle, so that the problem of conducting the anode and the cathode of the lithium ion battery caused by the wrinkle of the compound solid electrolyte can be reduced.

The embodiment of the application also provides a lithium ion battery. Referring to fig. 18, the method includes: a positive electrode 181, a negative electrode 182, a solid electrolyte 183, and at least one protective layer 184. A solid electrolyte 183 is disposed between the positive electrode 181 and the negative electrode 182.

It is to be noted that fig. 18 shows, by way of example only, the stacked relationship among the positive electrode 181, the negative electrode 182, the solid electrolyte 183, and the protective layer 184. In the actual application process, the positive electrode 181, the negative electrode 182, the solid electrolyte 183, and the protective layer 184 are bonded together in a stacked relationship shown in fig. 18.

Referring to fig. 18 (one), as one possible implementation, a protective layer 184 is disposed between the solid electrolyte 183 and the positive electrode 181.

Referring to fig. 18 (two), as one possible implementation, a protective layer 184 is disposed between the solid electrolyte 183 and the negative electrode 182.

Referring to fig. 18 (iii), as one possible implementation, one protective layer 184 (1) is disposed between the solid electrolyte 183 and the positive electrode 181, and the other protective layer 184 (2) is disposed between the solid electrolyte 183 and the negative electrode 182.

In the lithium ion battery provided by the embodiment of the application, the solid electrolyte 183 is arranged between the anode 181 and the cathode 182, and the solid electrolyte 183 plays a role in allowing Li+ to pass and isolating e-. And thus electrical isolation between the positive electrode 181 and the negative electrode 182 can be ensured.

The protective layer 184 is made of a film material provided in the embodiment of the present application. The film layer material may include: lithium salts, polyoxyethylene polymers and sulfonamide compounds.

The polyethylene oxide polymer as the matrix of the film material contains ether bonds. Ether linkages as sites may be incorporated with lithium salts to provide li+. The polyoxyethylene polymer molecules have chain segment movement, and the chain segment movement can drive the displacement of Li+ between different sites, so that the migration of Li+ between the positive electrode and the negative electrode is realized.

The sulfonamide compound can also be used as a plasticizer of the polyethylene oxide polymer, and intermolecular acting force exists between the sulfonamide compound and ether bonds in the polyethylene oxide polymer, and the intermolecular acting force can reduce the glass transition temperature of the polyethylene oxide polymer, so that the chain segment movement of the polyethylene oxide polymer is effectively promoted, and the protective layer 184 has better Li ⁺ conductivity.

The protective layer 184 has a relatively high Li ⁺ conductivity, and when applied to a lithium ion battery, no significant charge layer is formed between the protective layer 184 and the positive electrode 181/negative electrode 182. The protective layer 184 and the positive/negative electrodes 181/182 may form a stable interface that does not deteriorate with deposition/stripping of lithium during battery cycling, so that the lithium ion battery has stable cycle performance.

The protective layer 184 is formed by crosslinking a film material, and the protective layer 184 is in a solid state. Compared with a lithium ion battery adopting liquid electrolyte, the lithium ion battery provided by the embodiment of the application can avoid the safety problem caused by liquid electrolyte leakage.

The protective layer 184 has a certain toughness, can inhibit the growth of negative lithium dendrites, and plays a role in protecting the solid electrolyte 183, so that the safety performance of the lithium ion battery is improved.

The protective layer 184 formed by the crosslinked film material has a certain toughness, and the protective layer 184 can inhibit the growth of lithium dendrites and plays a role in protecting the solid electrolyte 183. Therefore, the lithium ion battery provided by the embodiment of the application can adopt the lithium metal negative electrode with higher specific capacity. Further, the lithium ion battery provided by the embodiment of the application is ensured to have higher energy density.

Because the positive electrode 181 and/or the negative electrode 182 in the lithium ion battery provided by the embodiment of the application are in contact with the protective layer 184. The protective layer 184 does not contain metals such as lanthanum and zirconium, even if the negative electrode 182 of the lithium ion battery adopts lithium metal, side reactions between the protective layer 184 and the lithium metal are less, the protective layer 184 has larger Li ⁺ conductivity, and a serious charge layer is not formed between the protective layer 184 and the positive electrode 181/the negative electrode 182. The lithium ion battery provided by the embodiment of the application can still have a relatively stable interface after repeated charge and discharge cycles. The lithium ion battery provided by the embodiment of the application can still have smaller interface impedance after repeated charge and discharge cycles.

The lithium ion battery provided by the embodiment of the application is further described below with reference to the specific drawings:

as an implementation manner, in the lithium ion battery provided in fig. 18, liFeO ₄ is used as the positive electrode 181; the negative electrode 182 is made of lithium metal; the solid electrolyte 183 employs LLZO; the protective layer 184 is made of a film material (PE) provided in the embodiment of the present application. The lithium ion battery provided by the present implementation may be referred to as li|pe|llzo|pe|li.

Comparative example 1a LLZO is provided between the positive electrode and the negative electrode, and the lithium ion battery provided in comparative example 1 may be represented as li|llzo|li.

Fig. 19 (a) shows a plot of imaginary-real impedance of li|llzo|li. Fig. 19 (two) is a plot of imaginary-real impedance versus imaginary-real impedance of li|pe|llzo|pe|li.

The imaginary impedance of li|llzo|li in the range of 2000ohm cm ²～5000ohm.cm² of the real impedance (one) in fig. 19 is the interface impedance between the solid electrolyte and the lithium metal anode. It can be seen that the interfacial impedance of Li LLZO Li is 2020 Ω.cm ².

The imaginary impedance of li|pe|llzo|pe|li within 200ohm.cm ²～650ohm.cm² in fig. 19 (two) is the interface impedance between the protective layer and the lithium metal anode. It can be seen that the interfacial impedance of Li|PE|LLZO|PE|Li is 300 Ω. Cm ². The lithium ion battery provided by the implementation mode has smaller interface impedance.

The lithium ion battery protective layer provided by the implementation mode is not added with redundant micromolecular solvent or dispersant molecules, so that the step of volatilizing the solvent is not required to be additionally added after the crosslinking, and the micromolecular solvent residue is avoided. Residual solvent molecules or small molecule polymer reaction precursors can have an impact on the performance of the cell during cycling.

Fig. 20 (one) is a graph showing the potential-cycle time relationship of li|llzo|li at 40 ℃ and a capacity of 0.1mAh/cm ², and fig. 20 (two) is a schematic diagram of LLZO after the li|llzo|li is cycled for 120 hours.

As can be seen in fig. 20 (one), after a cycle of li|llzo|li of about 30 hours, the battery short-circuit occurs in li|llzo|li. In fig. 20 (two), a large amount of by-products with lithium metal are deposited on the LLZO surface.

Fig. 21 (one) is a graph showing the potential versus cycle time provided by li|pe|llzo|pe|li at 40 ℃ and a surface capacity of 0.1mAh/cm ². It can be seen that after 800 hours of cycling at a higher temperature (40 ℃) the li|pe|llzo|pe|li still has better cycling performance, i.e. the protective layer and the lithium metal anode can still have a more stable interface after multiple charge and discharge cycles.

The potential versus cycle time curves obtained from the two experiments were almost identical. It can be seen that the lithium ion battery provided by the embodiment of the application has repeatability.

The graph (II) in FIG. 21 is a potential versus cycle time curve provided by Li|PE|LLZO|PE|Li at 25℃and a surface capacity of 0.1mAh/cm ². It can be seen that after 1000 hours of cycling at room temperature (25 ℃), the li|pe|llzo|pe|li still has better cycling performance, i.e., the protective layer and the lithium metal anode can still have a more stable interface after multiple charge and discharge cycles.

The li|pe|llzo|pe|li cycle performance test exhibited a smaller potential (0.05V) than other polymer systems in the prior literature (overpotential is large and very unstable, and the potential is also expanding as the cycle proceeds). The Li|PE|LLZO|PE|Li protective layer material provided by the embodiment of the application has larger Li+ conductivity and lithium ion migration number, and does not generate a serious charge layer in the battery cycle process, so that the overpotential measured by the Li|PE|LLZO|PE|Li is smaller. The protective layer may form a stable interface with the lithium metal anode that does not deteriorate with lithium deposition/exfoliation during battery cycling. After the cycle of charging and discharging the Li|PE|LLZO|PE|Li for many times, the protective layer and the lithium metal negative electrode can still have a stable interface.

The embodiment of the application also provides a lithium ion battery. Referring to fig. 22, the lithium ion battery includes: a positive electrode 221 and a negative electrode 222; a composite solid electrolyte 223. The composite solid electrolyte 223 may be disposed between the positive electrode 221 and the negative electrode 222, where the composite solid electrolyte 223 adopts a film material provided by the embodiment of the present application, and the film material includes: lithium salts, polyethylene oxide polymers, separator materials and sulfonamide compounds.

Note that fig. 22 shows, by way of example only, the stacked relationship between the positive electrode 221, the negative electrode 222, and the composite solid electrolyte 223. In the actual application process, the positive electrode 221, the negative electrode 222, and the composite solid electrolyte 223 are bonded together in the stacked relationship shown in fig. 22.

The separator material has a function of allowing Li ⁺ to pass through and isolating e ^-. Therefore, the composite solid electrolyte 223 has the function of allowing Li ⁺ to pass through and isolating e ^-, and thus can ensure electrical isolation between the positive electrode 221 and the negative electrode 222.

The sulfonamide compound can be used as a polyethylene glycol dimethacrylate dispersing agent, so that the sulfonamide compound, the polyethylene glycol dimethacrylate and the lithium salt can form a uniform system. The film material provided by the implementation mode does not need to adopt a small molecular solvent, so that the problem caused by the residual small molecular solvent does not exist.

The sulfonamide compound can also be used as a plasticizer of polyethylene glycol dimethacrylate, intermolecular acting force exists between the sulfonamide compound and ether bond in the polyethylene glycol dimethacrylate, and the intermolecular acting force can be used for the glass transition temperature of the polyethylene glycol dimethacrylate, so that the segment movement of the polyethylene glycol dimethacrylate is effectively promoted, and the composite solid electrolyte has better Li ⁺ conductivity.

The composite solid electrolyte 223 has a larger Li ⁺ conductivity, and when the composite solid electrolyte 223 is applied to a lithium ion battery, a serious charge layer is not formed between the composite solid electrolyte 223 and the positive electrode/the negative electrode. The composite solid electrolyte 223 and the positive/negative electrodes may form a stable interface that does not deteriorate with deposition/stripping of lithium during battery cycling, so that the lithium ion battery has stable cycling performance.

The composite solid electrolyte 223 is formed by crosslinking a film layer material, and the composite solid electrolyte 223 is in a solid state, so that compared with a lithium ion battery adopting a liquid electrolyte, the lithium ion battery provided by the embodiment of the application can reduce the safety problem caused by liquid electrolyte leakage.

The composite solid electrolyte 223 has certain toughness, and can inhibit the growth of negative lithium dendrites. Therefore, the lithium ion battery provided by the embodiment of the application can adopt the lithium metal negative electrode with higher specific capacity. Thereby ensuring that the lithium ion battery has higher energy density.

The positive electrode 221/negative electrode 222 of the lithium ion battery provided by the embodiment of the application is in contact with the composite solid electrolyte 223. The composite solid electrolyte 223 does not contain metals such as lanthanum and zirconium, and even if the lithium metal is used as the negative electrode 222 of the lithium ion battery, the side reaction between the composite solid electrolyte 223 and the lithium metal is less. The composite solid electrolyte 223 and the positive electrode 221/negative electrode 222 can still have a relatively stable solid-solid interface after multiple charge-discharge cycles. The lithium ion battery provided by the embodiment of the application can still have smaller interface impedance after repeated charge and discharge cycles.

As a possible implementation manner, the separator material in the lithium ion battery provided in fig. 22 may be simply referred to as a composite PE, and the lithium ion battery provided in fig. 22 may be referred to as a li|composite pe|li symmetric battery. The cycle performance of the li|composite pe|li symmetric battery was tested at 25 ℃ and 40 ℃. The test results can be seen in fig. 23 and 24.

Fig. 23 (one) shows a potential-cycle time curve provided by li|composite pe|li at 40 ℃ and a surface capacity of 2mAh/cm ² for a li|composite pe|li symmetric battery. It can be seen that after 1100 cycles at a higher temperature (40 ℃), the li|composite pe|li symmetric battery still has a better cycle performance, i.e., the composite solid electrolyte and the positive electrode 221/negative electrode 222 can still have a more stable solid-solid interface after multiple charge and discharge cycles.

Another li|composite pe|li symmetric cell in fig. 23 (two) provides a potential versus cycle time curve for li|composite pe|li at 40 ℃ with a face capacity of 2mAh/cm ². The relationship provided in (one) in fig. 23 is almost identical to the relationship provided in (two) in fig. 23. It can be seen that the lithium ion battery provided by the embodiment of the application has repeatability.

Fig. 24 (one) shows a potential-cycle time curve provided by li|composite pe|li at 25 ℃ and a surface capacity of 2mAh/cm ² for a li|composite pe|li symmetric battery. It can be seen that after 1100h of cycling at 25 ℃, the li|composite pe|li still has better cycling performance on the li|composite pe|li, i.e. the composite solid electrolyte and the positive electrode 221/negative electrode 222 can still have a more stable solid-solid interface after multiple charge and discharge cycles.

Another li|composite pe|li symmetric cell in fig. 24 (two) provides a potential versus cycle time curve for li|composite pe|li at 25 ℃ with a face capacity of 2mAh/cm ². The relationship provided in (one) in fig. 24 is almost identical to the relationship provided in (two) in fig. 24. It can be seen that the lithium ion battery provided by the embodiment of the application has repeatability.

The embodiment of the application also provides a preparation method of the lithium ion battery, referring to fig. 25 and 26, fig. 25 is a flowchart of the preparation method of the lithium ion battery, and fig. 26 is a process flowchart of the preparation method provided in fig. 25, the preparation method includes:

s251: and adding an initiator into the film material to obtain a polymer precursor.

The film layer material comprises: polyethylene oxide polymer, lithium salt and sulfonamide compound.

As one possible implementation, the molecular structure of the sulfonamide compound is an asymmetric structure. The embodiment of the application also provides a preparation process of the sulfonamide compound with an asymmetric molecular structure, and particularly can be seen in fig. 27.

Specific synthetic steps of the sulfonamide compound can include:

(1) The sulfamoyl chloride was slowly added dropwise to a mixed solution of sulfamoyl chloride/triethylamine (Et ₃ N)/dichloromethane (dichloromethane, DCM).

(2) Stirring at room temperature for reacting for hours;

(3) Sequentially cleaning with hydrochloric acid, sodium bicarbonate solution and sodium chloride solution to remove unreacted raw materials and salts formed; wherein the raw materials comprise unreacted sulfamoyl chloride, ethylmethylamine, triethylamine, dichloromethane and the like. Salts may include: sodium bicarbonate, sodium chloride, and the like.

(3) And drying the solvent to obtain the sulfonamide compound.

The sulfonamide compound with an asymmetric molecular structure is not easy to generate close intermolecular stacking, and is not easy to form a local structure of plasticizing crystals. The plasticizing crystal can reduce the plasticizing performance of the sulfonamide compound, so the sulfonamide compound has larger plasticizing performance.

In the embodiment of the application, the initiator is heated to decompose into a compound of free radical, which can be used for initiating the cross-linking reaction of the polyethylene oxide polymer, so that the polyethylene oxide polymer forms a cross-linking system. The initiator may be, but is not limited to, azobisisobutyronitrile (Azobisisobutyronitrile, AIBN).

The morphology of the polymer precursor can be seen in fig. 26 (one). Wherein the polymer precursor is in a liquid state.

S252: and forming the lithium ion battery by utilizing the positive electrode, the negative electrode and the polymer precursor.

The lithium ion battery includes: the lithium ion battery includes: the positive electrode, negative electrode, and the compound solid electrolyte that sets up between positive electrode and negative electrode, compound solid electrolyte by the rete material forms. The film layer material comprises: polyethylene oxide polymer, lithium salt, diaphragm material and sulfonamide compound.

The step of forming a lithium ion battery using the positive electrode, the negative electrode, and the polymer precursor includes: s11 to S12.

S11: the polymer precursor is treated such that the polymer precursor forms a composite solid electrolyte.

The implementation of treating the polymer precursor may be, but is not limited to, heat treatment, or illumination.

In the heat treatment or illumination process, the initiator mixed in the film material can form free radicals, and under the action of the free radicals, the polyethylene oxide polymer in the polymer precursor is subjected to crosslinking reaction, so that the polymer precursor forms a composite solid electrolyte, and the morphology of the composite solid electrolyte can be seen in (II A) in fig. 26.

S12: and assembling the anode, the cathode and the composite solid electrolyte to obtain the lithium ion battery.

The lithium ion battery formed can be referred to as (tri a) in fig. 26.

As one possible implementation, forming a lithium ion battery implementation method using a positive electrode, a negative electrode, and a polymer precursor may include S21-S22.

S21: assembling the positive electrode, the negative electrode and the polymer precursor.

Referring to fig. 26 (B), it can be seen that the positive electrode and the negative electrode are spaced apart, and the polymer precursor is injected between the positive electrode and the negative electrode.

The process of assembling the positive electrode, the negative electrode, and the polymer precursor will be described below with reference to specific examples. Please refer to fig. 28, which is a cross-sectional view of a lithium ion battery. A polymer precursor may be injected between the positive and negative electrodes of a lithium ion battery.

Referring to fig. 29, a cross-sectional view of a cell is shown, in which a polymer precursor may be injected between the positive and negative electrodes of the cell.

S22: the polymer precursor is treated such that the polymer precursor forms a composite solid electrolyte.

During heat treatment or irradiation, the initiator incorporated in the polymer precursor may form free radicals. Under the action of free radicals, the polyethylene oxide polymer in the polymer precursor is subjected to crosslinking reaction, the polymer precursor is converted into a composite solid electrolyte, and the formed lithium ion battery can be referred to as (three B) in fig. 26.

The lithium ion battery prepared by the embodiment of the application comprises: a positive electrode, a negative electrode, and a composite solid electrolyte disposed between the positive electrode and the negative electrode. The composite solid electrolyte is formed from a polymer precursor including a film material and an initiator. The membrane layer material (including the membrane material) includes: polyethylene oxide polymer, lithium salt, diaphragm material and sulfonamide compound.

The effect of the preparation method can be obtained by referring to any one possible implementation mode of the film material/film/lithium ion battery.

The embodiment of the application also provides a preparation method of the lithium ion battery, and refer to fig. 30 and 31. Fig. 30 is a flowchart of a preparation method of a lithium ion battery, and fig. 31 is a process flowchart of the preparation method provided in fig. 30, the preparation method comprising:

s301: and adding an initiator into the film material to obtain a polymer precursor.

The specific implementation process may refer to the above embodiment, and will not be described herein.

S302: and forming the lithium ion battery by using the positive electrode, the negative electrode, the solid electrolyte and the polymer precursor.

The implementation process of forming a lithium ion battery using a positive electrode, a negative electrode, a solid electrolyte, and a polymer precursor may include S31 to S33:

s31: a polymer precursor is coated on at least one surface of the solid electrolyte.

The morphology of the solid electrolyte surface coated with the polymer precursor can be seen in fig. 31 (one).

S32: the polymer precursor is treated such that the polymer precursor forms a protective layer.

During heat treatment or irradiation, the initiator may generate free radicals. Under the action of free radicals, the polyethylene oxide polymer undergoes a crosslinking reaction, so that the polyethylene oxide polymer forms a crosslinking system (solid state), and the film material forms a protective layer.

The morphology of the protective layer and the solid electrolyte can be referred to as (two a) in fig. 31. The (di a) in fig. 31 is merely an example showing an example in which a protective layer is formed on the surface of the solid electrolyte adjacent to the positive electrode and the surface adjacent to the negative electrode. In the practical application, the protective layer may be formed only on the surface of the solid electrolyte adjacent to the positive electrode, or only on the surface of the solid electrolyte adjacent to the negative electrode.

S33: and assembling the anode, the cathode and the solid electrolyte with the protective layer on the surface to obtain the lithium ion battery.

The lithium ion battery formed can be referred to as (tri a) in fig. 31.

The implementation process of forming a lithium ion battery using a positive electrode, a negative electrode, and a solid electrolyte surface coated with a polymer precursor may include S41 to S42:

s41: the positive electrode, the negative electrode, the polymer precursor, and the solid electrolyte are assembled.

Referring to fig. 31 (B), it can be seen that the positive electrode and the negative electrode are spaced apart, and a solid electrolyte is disposed between the positive electrode and the negative electrode. The solid state electrolyte may electrically isolate the positive electrode from the negative electrode. A polymer precursor is added between the positive electrode and the solid electrolyte, and between the negative electrode and the solid electrolyte.

The process of assembling the positive electrode, the negative electrode, and the composite precursor will be described below with reference to specific examples. Please refer to fig. 32, which is a cross-sectional view of a lithium ion battery. A solid electrolyte may be disposed between the positive and negative electrodes of the lithium ion battery, and a polymer precursor may be injected between the positive and solid electrolytes, and between the negative electrode and the solid electrolyte.

Referring to fig. 33, fig. 33 is a cross-sectional view of a cell in which a solid electrolyte is disposed between a positive electrode and a negative electrode, and a polymer precursor is injected between the positive electrode and the solid electrolyte, and between the negative electrode and the solid electrolyte.

S42: the polymer precursor is treated such that the polymer precursor forms a protective layer.

During heat treatment, or irradiation, the initiator may generate free radicals. Under the action of free radicals, the polyethylene oxide polymer undergoes a crosslinking reaction, so that the polyethylene oxide polymer forms a crosslinking system (solid state), and the film material forms a protective layer. The formed lithium ion battery can be referred to as (tri B) in fig. 31.

The lithium ion battery prepared by the embodiment of the application comprises: a positive electrode, a negative electrode, a solid electrolyte and at least one protective layer. And a solid electrolyte disposed between the positive electrode and the negative electrode, at least one protective layer formed from a polymer precursor. The protective layer is disposed between the solid electrolyte and the positive electrode, and/or between the solid electrolyte and the negative electrode. The protective layer is formed from a polymer precursor that includes a film material and an initiator. The film layer material comprises: polyethylene oxide polymer, lithium salt and sulfonamide compound.

In the description of the present specification, a particular feature, structure, material, or characteristic may be combined in any suitable manner in one or more embodiments or examples.

The foregoing is merely illustrative embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily think about variations or substitutions within the technical scope of the present application, and the application should be covered. Therefore, the protection scope of the application is subject to the protection scope of the claims.

Claims

1. A film material for forming a film, the film material comprising:

Polyethylene glycol dimethacrylate;

Sulfonamide compounds;

And (3) a lithium salt.

2. The film material of claim 1, further comprising: polyethylene glycol monomethyl ether methacrylate.

3. The film material according to claim 2, wherein the molar ratio of polyethylene glycol dimethacrylate to polyethylene glycol monomethyl ether methacrylate is between 1:10 and 10:1.

4. A film material according to any one of claims 1 to 3, wherein the molecular structure of the sulfonamide compound is an asymmetric structure.

5. The film material of any one of claims 1-4, wherein the substituents of the sulfonamide compound include: methyl, ethyl or ether groups.

6. The film material of any one of claims 1-5, wherein the lithium salt comprises: lithium bis (fluorosulfonyl) imide and lithium bis (trifluoromethyl) sulfonyl imide.

7. The film material according to claim 6, wherein the mass ratio of the lithium bis (trifluoromethyl) sulfonyl imide to the lithium bis (trifluoromethyl) sulfonyl imide is 1:2 to 2:1.

8. The film material according to any one of claims 1 to 7, wherein the mass fraction of the sulfonamide compound is 40% to 60%.

9. The film material according to any one of claims 2 to 8, wherein the relative molecular mass of polyethylene glycol dimethacrylate/polyethylene glycol monomethyl ether methacrylate is 300 to 600.

10. The film material according to any one of claims 2 to 9, wherein the degree of polymerization of the polyethylene glycol dimethacrylate/the polyethylene glycol monomethyl ether methacrylate is between 4 and 12.

11. The film material according to any one of claims 2 to 10, wherein a molar ratio of ether bond to lithium ion in the film material is 10 to 30, the ether bond being provided by the polyethylene glycol dimethacrylate and the polyethylene glycol monomethyl ether methacrylate, and the lithium ion being provided by the lithium salt.

12. The film material of any one of claims 1-11, wherein the concentration of lithium salt is less than or equal to 25%.

13. The film material of any one of claims 1-12, wherein the film material has flowability.

14. The film material of any one of claims 1-13, further comprising: a separator material.

15. A film layer, characterized in that the film layer comprises the film layer material according to any one of claims 1 to 14 and an initiator, and the initiator is used for curing the film layer material.

16. The film of claim 15, wherein the film has self-supporting properties.

17. A lithium ion battery, comprising: a positive electrode and a negative electrode;

a composite solid electrolyte disposed between the positive electrode and the negative electrode, the composite solid electrolyte comprising: the film material of claim 14 and an initiator.

18. A lithium ion battery, comprising: a positive electrode and a negative electrode;

A solid electrolyte disposed between the positive electrode and the negative electrode;

At least one protective layer, the protective layer is set up between said solid electrolyte and said positive pole, and/or between said solid electrolyte and said negative pole, the material used for the protective layer includes: a film material and an initiator as claimed in any one of claims 1 to 12.

19. A method for preparing a lithium ion battery, comprising:

Adding an initiator into the film material of claim 14 to obtain a polymer precursor, and forming a lithium ion battery by using the positive electrode, the negative electrode and the polymer precursor; the lithium ion battery includes: a positive electrode, a negative electrode, and a composite solid electrolyte disposed between the positive electrode and the negative electrode, the composite solid electrolyte formed from the membrane layer material.

20. The method of preparing a lithium ion battery of claim 19, wherein the step of forming a lithium ion battery using the positive electrode, the negative electrode, and the polymer precursor comprises:

Treating the polymer precursor such that the polymer precursor forms the composite solid electrolyte;

and assembling the positive electrode, the negative electrode and the composite solid electrolyte to obtain the lithium ion battery.

21. The method of preparing a lithium ion battery of claim 19, wherein the step of forming a lithium ion battery using the positive electrode, the negative electrode, and the polymer precursor comprises:

Assembling the positive electrode, the negative electrode, and the polymer precursor;

treating the polymer precursor such that the polymer precursor forms the composite solid electrolyte.

22. A method for preparing a lithium ion battery, comprising:

adding an initiator into the film material according to any one of claims 1 to 13 to obtain a polymer precursor;

Forming a lithium ion battery using a positive electrode, a negative electrode, a solid electrolyte, and the polymer precursor, the lithium ion battery comprising: the positive electrode, the negative electrode, the solid electrolyte and at least one protective layer, the solid electrolyte is arranged between the positive electrode and the negative electrode, the at least one protective layer is formed by the film material, and the protective layer is arranged between the solid electrolyte and the positive electrode and/or between the solid electrolyte and the negative electrode.

23. The method of claim 22, wherein forming a lithium ion battery using the positive electrode, the negative electrode, and the solid electrolyte surface coated with the polymer precursor comprises:

Coating a polymer precursor on the surface of the solid electrolyte;

Treating the polymer precursor such that the polymer precursor forms the protective layer;

and assembling the positive electrode, the negative electrode and the solid electrolyte with the protective layer on the surface to obtain the lithium ion battery.

24. The method of claim 22, wherein forming a lithium ion battery using the positive electrode, the negative electrode, the solid state electrolyte, and the polymer precursor comprises:

assembling a positive electrode, a negative electrode, a solid electrolyte and the polymer precursor;

the polymer precursor is treated such that the polymer precursor forms the protective layer.