A polyformaldehyde-based halide composite solid-state electrolyte and a preparation method thereof

Abstract

This invention relates to a polyoxymethylene-based halide composite solid electrolyte, comprising polyoxymethylene, lithium / sodium salt, halide, plasticizer, and organic solvent; the mass ratio of polyoxymethylene, lithium / sodium salt, halide, plasticizer, and organic solvent is 1:0.08~2:0.001~0.55:0.01~1:6~120. This invention introduces a suitable formulation ratio to achieve a balance between the mechanical strength and ion conduction of the solid electrolyte. Polyoxymethylene, as the main material, provides mechanical strength, ensuring the self-support of the structure, thermal stability, and inhibiting dendrite growth. Small amounts of halide, plasticizer, and organic solvent do not affect the overall mechanical strength and significantly improve lithium-ion migration efficiency, broaden the electrochemical stability window, and enhance ionic conductivity.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolytes, and particularly relates to a polyoxymethylene-based halide composite solid electrolyte and its preparation method. Background Technology

[0002] Among various battery technologies, active metal (such as lithium and sodium) batteries have an energy density more than twice that of traditional ion batteries and are considered the most promising next-generation energy storage devices. However, due to the high volatility and flammability of the organic liquid electrolytes used, the safety issues of high-energy batteries are becoming increasingly serious. Furthermore, the presence of highly active metal anodes limits the long cycle life of batteries due to the use of liquid electrolytes. Compared to liquid batteries, solid-state batteries are safer, have longer cycle life, and require less sophisticated packaging and state-of-charge monitoring circuitry. Polymer solid-state electrolytes and halide solid-state electrolytes have attracted much attention as mainstream technologies; the former excels in processability, while the latter boasts a wide electrochemical window and high ionic conductivity. However, both still face significant structural bottlenecks and several key technological obstacles that have yet to be overcome in the process of commercialization.

[0003] 1. Advantages and inherent drawbacks of traditional polymer solid electrolytes: Polymer matrices, such as polyethylene oxide, polyvinylidene fluoride, and polytetrafluoroethylene, are lightweight, flexible, and easily compatible with commercial electrode processes. However, their room temperature ionic conductivity (…) ) and ion transport number ( The voltage window of polymer solid electrolytes is typically very low, which leads to the aggregation and polarization of lithium ions, forming lithium dendrites that pierce the polymer electrolyte, which has low mechanical strength, and ultimately cause the battery to short-circuit and fail. The low voltage window of polymer solid electrolytes also limits the improvement of battery energy density. Furthermore, polymers are prone to softening and even decomposition at high temperatures, posing safety hazards.

[0004] 2. Advantages and inherent drawbacks of halide solid electrolytes: Halide solid electrolytes possess high ionic conductivity and excellent electrochemical stability, especially exhibiting outstanding oxidation resistance for high-voltage cathode materials. However, the rigid halide particles make it difficult to fabricate large-area, ultrathin self-supporting films, limiting their commercial value. Furthermore, the rigid contact with the electrode results in high contact impedance, making them susceptible to changes in electrode volume, potentially leading to detachment from the electrode during long cycles and causing battery open-circuit failure. In addition, halides readily react with moisture or oxygen in the air, disrupting their inherent crystal structure and causing them to lose their ion-transporting function.

[0005] 3. Bottlenecks in composite solid electrolyte strategies: Traditional composite strategies such as simple blending and coating often fail to achieve synergistic performance gains and instead lead to intensified interfacial reactions and blocked ion transport pathways.

[0006] In summary, single solid-state electrolyte systems or simple composite solid-state electrolyte systems struggle to simultaneously possess flexibility, processability, high ionic conductivity, a wide voltage window, and good interfacial contact. Therefore, there is an urgent need in this field for an innovative solution originating from the material formulation stage. This solution aims to design a novel, multi-component synergistic composite solid-state electrolyte material system to achieve complementary and synergistic effects at the molecular scale, improve interfacial contact, simplify battery assembly processes, significantly enhance the room-temperature ionic conductivity of the polymer bulk, and promote its practical application in solid-state batteries.

[0007] For example, in the cross-linked polymer and its preparation method, electrolyte composition, polymer electrolyte and its preparation method, lithium-ion battery and electrical device (CN119060331A), a cross-linked network with synergistic hydrogen and covalent bonds was designed. Hydrogen bonds provide dynamic self-healing capability, while covalent bonds ensure structural stability, aiming to improve mechanical strength and interfacial stability. This cross-linked structure design may increase process complexity and manufacturing cost. The long-term chemical stability and electrochemical stability under high voltage of the hydrogen-covalent composite structure require further verification. In another example, in the bicontinuous phase eutectic polymer solid electrolyte and pouch battery and its preparation method (CN119230933B), two polymers are used to form a bicontinuous phase eutectic structure, creating interpenetrating, continuous ion transport channels, aiming to achieve a balance between high conductivity and high mechanical strength. However, the eutectic system is extremely sensitive to the control of raw material purity, mixing ratio, and phase separation process, has a narrow process window, and makes it difficult to guarantee repeatability and uniformity in large-scale production. The composite solid electrolyte, its preparation method, and battery (CN120749210A) introduces polyoxymethylene (POM) to improve the interfacial contact between the oxide and metal electrodes while maintaining high ionic conductivity. However, the drying process lacks precise temperature control, leading to easy formation of pores and cracks in the solid electrolyte membrane due to solvent evaporation, resulting in poor membrane density and uneven strength. This approach directly introduces a large number and variety of inorganic fillers, but fails to address key challenges such as poor interfacial compatibility, side reactions, and filler agglomeration between these fillers and the POM matrix. This can lead to discontinuous ion transport channels, with actual conductivity far lower than theoretical values, and questionable long-term cycling stability. The halide oxide solid electrolyte, its preparation method, and application (CN120784471B) synthesizes a novel "halogen oxide" solid electrolyte material by introducing oxygen into a halide solid electrolyte, utilizing the regulatory effect of oxygen on crystal structure to improve its ionic conductivity and electrochemical stability. As a mixed system, the microstructure of halide oxides and whether oxygen will trigger side reactions under high voltage are technical risks that require attention. Composite solid electrolyte films and their preparation methods, and roll-up all-solid-state batteries (CN119275340A). Polymer fiber networks provide a flexible substrate and sufficient mechanical strength, allowing the films to be bent and folded, thus adapting to roll-up battery processes. However, the interfacial compatibility between the polymer and oxide fillers is a key issue. Uneven filling and filler agglomeration can lead to blockage of ion transport channels, affecting overall performance. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a polyoxymethylene-based halide composite solid electrolyte.

[0009] The present invention also provides a method for preparing a polyoxymethylene-based halide composite solid electrolyte.

[0010] A polyoxymethylene-based halide composite solid electrolyte, characterized in that it comprises polyoxymethylene, lithium / sodium salt, halide, plasticizer and organic solvent; wherein the mass ratio of polyoxymethylene, lithium / sodium salt, halide, plasticizer and organic solvent is 1:0.08~2:0.001~0.55:0.01~1:6~120.

[0011] According to claim 1, the polyoxymethylene-based halide composite solid electrolyte is characterized in that the molecular weight of the polyoxymethylene is 500 to 5,000,000.

[0012] Further, the lithium salt comprises at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2), lithium borate (LiBOB), lithium difluorooxalate borate (LiDFOB), lithium tetrafluorooxalate phosphate (LiPF4(C2O4)), lithium hexafluorophosphate (LiPF6), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), and lithium perchlorate (LiClO4). One; the sodium salt comprises at least one selected from sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium bis(fluorosulfonyl)imide (NaFSI), sodium tetrafluoroborate (NaBF4), sodium difluorophosphate (NaPO2F2), sodium borate (NaBOB), sodium difluorooxalate borate (NaDFOB), sodium tetrafluorooxalate phosphate (NaPF4(C2O4)), sodium hexafluorophosphate (NaPF6), sodium chloride (NaCl), sodium bromide (NaBr), sodium iodide (NaI), and sodium perchlorate (NaClO4).

[0013] Further, the plasticizer includes at least one selected from succinic anhydride, glutaronitrile, adiponitrile, 2-methylsuccinic anhydride, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 15-crown-5-ether, 18-crown-6-ether, 1,3-dioxolane, ethylene carbonate, dimethyl carbonate, propylene carbonate, diethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, and 1,3-propanesulfonate lactone.

[0014] Further, the general chemical formula of the halide is AxByCz or AxByOCz, where x > 0, y > 0, z > 0; A is selected from Li + Na + One of them; B is selected from Cr 3+ V 3+ Fe 3+ Co 3+ Ni 3+ Ti 3+ ,Sc 3+ Lu 3+ Y3+ Al 3+ Ga 3+ In 3+ Yb 3+ Tm 3+ Er 3+ Ho 3+ Dy 3+ 、Tb 3+ Gd 3+ Eu 3+ 、Sm 3+ Pm 3+ 、Nd 3+ Pr 3+ Ce 3+ La 3+ Be 2+ Mg 2+ Ca 2 + Cu 2+ Zn 2+ 、Sr 2+ Cd 2+ Pb 2+ Ba 2+ Ti 4+ Zr 4+ Hf 4+ Sn 4+ 、Ge 4+ Si 4+ 、Nb 5+ Ta 5+ At least one of them; C is selected from At least one of them.

[0015] Furthermore, the organic solvent includes at least one of N-methylpyrrolidone, tetrahydrofuran, dichloromethane, acetone, dimethylformamide, methyl ethyl ketone, chloroform, 1,4-dioxane, toluene, benzene, dimethyl sulfoxide, and sulfolane.

[0016] A method for preparing a polyoxymethylene-based halide composite solid electrolyte, wherein the preparation method is a solvent blending and drying film-forming process, comprising the following steps:

[0017] (1) Preparation of polymer solution: Take materials according to the formula, and mix polyoxymethylene and organic solvent at 155~190 °C to prepare polymer solution;

[0018] (2) Preparation of solid electrolyte slurry: The polymer solution, lithium / sodium salt, halide and plasticizer are ground at 155~190 ℃ for 1~10 min to prepare solid electrolyte slurry;

[0019] (3) Preparation of solid electrolyte: The solid electrolyte slurry is uniformly coated on a substrate that can withstand a temperature of 200 ℃ and dried at 155~190 ℃ for 0.1~3 h to prepare polyoxymethylene halide composite solid electrolyte.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention introduces a polyoxymethylene (POM) component. The highly regular molecular chains of POM impart excellent mechanical strength, dimensional stability, and film-forming properties to the electrolyte, effectively suppressing lithium dendrite growth and contributing to improved long-term battery stability. The high density of oxygen atoms in the POM backbone shortens the transport distance between oxygen atoms, giving the matrix ideal intrinsic ionic conductivity. Furthermore, the POM matrix exhibits excellent thermal stability, preventing the electrolyte from softening and deforming at high temperatures, thus reducing the battery's thermal safety risks.

[0022] 2. In this invention, halides possess a wide electrochemical stability window and high ionic conductivity, enhancing the stability of the composite solid electrolyte for high-voltage electrodes. The flexible polyoxymethylene (POM) matrix can form soft contacts with the electrode surface, which helps reduce the contact resistance between the electrolyte and the electrode, improving battery stability during cycling. Furthermore, POM isolates the halides from air, improving the environmental stability of the solid electrolyte and reducing environmental management costs. The halide particles act like plasticizers, reducing the intermolecular forces between POM molecular chains and further lowering the ion transport barrier; the combination of these two components synergistically constructs an efficient lithium-ion transport channel.

[0023] 3. In this invention, a plasticizer is introduced to reduce the crystallinity of polyoxymethylene (POM), enhance chain segment mobility, and its high dielectric constant promotes lithium salt dissociation, further improving the ionic conductivity of the solid electrolyte. Furthermore, the plasticizer enhances the flexibility and adhesion of the electrolyte, strengthens the interfacial contact between the electrolyte and rough electrodes, thereby reducing interfacial impedance.

[0024] 4. This invention introduces organic solvents to achieve uniform mixing of raw materials at the molecular level. After the solvent evaporates, internal defects in the electrolyte are reduced. Under a controllable drying process, the trace amounts of organic solvent remaining in the system are distributed among the components, weakening the electrostatic interaction between the polar groups of the polymer and the lithium / sodium salt anions, thereby lowering the migration barrier of lithium / sodium ions. This maintains the overall structural integrity of the electrolyte while accelerating ion transport kinetics.

[0025] 5. This invention introduces a suitable formulation ratio to achieve a balance between the mechanical strength and ion conduction of the solid electrolyte. Polyoxymethylene (POM) serves as the main material, providing mechanical strength and ensuring the structure's self-support, thermal stability, and dendrite growth inhibition. Small amounts of halides, plasticizers, and organic solvents do not affect the overall mechanical strength and significantly improve lithium-ion migration efficiency, broaden the electrochemical stability window, and enhance ionic conductivity. Detailed Implementation

[0026] The present invention will be further described below with reference to embodiments. The following description of the embodiments is only for the purpose of helping to understand the present invention.

[0027] Example 1: A polyoxymethylene-based halide composite solid electrolyte, comprising polyoxymethylene, lithium salt, halide, plasticizer, and organic solvent; the mass ratio of polyoxymethylene, lithium / sodium salt, halide, plasticizer, and organic solvent is 1:0.08:0.001:0.01:6. The molecular weight of polyoxymethylene is 500~5,000,000, the lithium salt includes lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), the plasticizer includes succinate, and the organic solvent includes N-methylpyrrolidone. The general chemical formula of the halide is: AxByCz, where x = 3, y = 1, z = 6; A is selected from Li + B is selected from Y 3+ C is selected from .

[0028] Example 2: A polyoxymethylene-based halide composite solid electrolyte, comprising polyoxymethylene, sodium salt, halide, plasticizer, and organic solvent; the mass ratio of polyoxymethylene, lithium / sodium salt, halide, plasticizer, and organic solvent is 1:1:0.2:0.5:60. The molecular weight of polyoxymethylene is 500~5,000,000, the sodium salt includes sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), the plasticizer includes glutaronitrile, and the organic solvent includes dimethylformamide. The general chemical formula of the halide is: AxByOCz, where x = 2, y = 1, z = 4; A is selected from Na... + B is selected from Nb 5+ C is selected from .

[0029] Example 3: A polyoxymethylene-based halide composite solid electrolyte, comprising polyoxymethylene, lithium salt, halide, plasticizer, and organic solvent; the mass ratio of polyoxymethylene, lithium / sodium salt, halide, plasticizer, and organic solvent is 1:2:0.55:1:120. The molecular weight of polyoxymethylene is 500~5,000,000. The lithium salt includes lithium difluorooxalate borate (LiDFOB), and the plasticizer includes adiponitrile. The organic solvent includes dimethyl sulfoxide. The general chemical formula of the halide is: AxByCz, where x = 2, y = 1, z = 6; A is selected from Li + B is selected from Zr4+ C is selected from .

[0030] Example 4: Referring to Example 1, the lithium salt can be a lithium salt or a sodium salt. The lithium salt includes lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2), lithium borate (LiBOB), lithium difluorooxalate borate (LiDFOB), lithium tetrafluorooxalate phosphate (LiPF4(C2O4)), lithium hexafluorophosphate (LiPF6), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), and lithium perchlorate (Li...). At least one of the following sodium salts: sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium bis(fluorosulfonyl)imide (NaFSI), sodium tetrafluoroborate (NaBF4), sodium difluorophosphate (NaPO2F2), sodium borate (NaBOB), sodium difluorooxalate borate (NaDFOB), sodium tetrafluorooxalate phosphate (NaPF4(C2O4)), sodium hexafluorophosphate (NaPF6), sodium chloride (NaCl), sodium bromide (NaBr), sodium iodide (NaI), and sodium perchlorate (NaClO4). Plasticizers include at least one of succinic anhydride, glutaronitrile, adiponitrile, 2-methylsuccinic anhydride, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 15-crown-5-ether, 18-crown-6-ether, 1,3-dioxolane, ethylene carbonate, dimethyl carbonate, propylene carbonate, diethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, and 1,3-propanesulfonate lactone. Organic solvents include at least one of N-methylpyrrolidone, tetrahydrofuran, dichloromethane, acetone, dimethylformamide, methyl ethyl ketone, chloroform, 1,4-dioxane, toluene, benzene, dimethyl sulfoxide, and sulfolane. The general chemical formula of the halides is AxByCz or AxByOCz, where x > 0, y > 0, z > 0; A is selected from Li + Na + One of them; B is selected from Cr 3+ V 3+ Fe 3+ Co 3+ Ni 3+ Ti 3+ ,Sc 3+ Lu 3+ Y 3+ Al 3+ Ga 3+ In 3+ Yb 3+ Tm 3+ Er 3+ Ho 3+ Dy 3+、Tb 3+ Gd 3+ Eu 3+ 、Sm 3+ Pm 3+ 、Nd 3+ Pr 3+ Ce 3+ La 3+ Be 2+ Mg 2+ Ca 2+ Cu 2+ Zn 2+ 、Sr 2+ Cd 2+ Pb 2+ Ba 2 + Ti 4+ Zr 4+ Hf 4+ Sn 4+ 、Ge 4+ Si 4+ 、Nb 5+ Ta 5+ At least one of them; C is selected from At least one of them.

[0031] Example 5: A method for preparing a polyoxymethylene-based halide composite solid electrolyte, wherein the preparation method is a solvent blending and drying film-forming process, including the following steps:

[0032] (1) Preparation of polymer solution: The polymer solution was prepared by taking materials according to the formulation of Example 1 and mixing polyoxymethylene and organic solvent at 155°C.

[0033] (2) Preparation of solid electrolyte slurry: The polymer solution, lithium salt, halide and plasticizer are ground at 155℃ for 1 min to prepare solid electrolyte slurry;

[0034] (3) Preparation of solid electrolyte: The solid electrolyte slurry is uniformly coated on a substrate that can withstand a temperature of 200℃ and dried at 155℃ for 0.1h to prepare a polyoxymethylene halide composite solid electrolyte.

[0035] Example 6: A method for preparing a polyoxymethylene-based halide composite solid electrolyte, wherein the preparation method is a solvent blending and drying film-forming process, including the following steps:

[0036] (1) Preparation of polymer solution: The polymer solution was prepared by taking materials according to the formulation of Example 2, and mixing polyoxymethylene and organic solvent at 170 °C.

[0037] (2) Preparation of solid electrolyte slurry: The polymer solution, lithium / sodium salt, halide and plasticizer were ground at 170 °C for 5 min to prepare solid electrolyte slurry;

[0038] (3) Solid electrolyte preparation: The solid electrolyte slurry was uniformly coated on a substrate (glass) that could withstand a temperature of 200 ℃ and dried at 170 ℃ for 1 h to prepare a polyoxymethylene halide composite solid electrolyte.

[0039] Example 7: A method for preparing a polyoxymethylene-based halide composite solid electrolyte, wherein the preparation method is a solvent blending and drying film-forming process, including the following steps:

[0040] (1) Preparation of polymer solution: The polymer solution was prepared by taking materials according to the formulation of Example 1 and mixing polyoxymethylene and organic solvent at 190 °C.

[0041] (2) Preparation of solid electrolyte slurry: The polymer solution, lithium / sodium salt, halide and plasticizer were ground at 190 °C for 10 min to prepare solid electrolyte slurry;

[0042] (3) Preparation of solid electrolyte: The solid electrolyte slurry was uniformly coated on a substrate that could withstand a temperature of 200℃ and dried at 190℃ for 3 h to prepare a polyoxymethylene halide composite solid electrolyte.

[0043] Comparative Example 1: Referring to Example 1, polyoxymethylene was replaced with polyethylene oxide.

[0044] Comparative Example 2: Referring to Example 1, the plasticizer was removed from the formulation.

[0045] Comparative Example 3: Referring to Example 2, the mass ratio of polyoxymethylene, sodium salt, halide, plasticizer, and organic solvent was 1:0.8:0.01:5:20.

[0046] Comparative Example 4: Refer to Example 2, but remove the sodium salt from the formula.

[0047] Comparative Example 5: Refer to Example 3, but remove the halides from the formula.

[0048] Comparative Example 6: Referring to Example 5, the ingredients were prepared according to the formula of Comparative Example 1.

[0049] Comparative Example 7: Referring to Example 5, the ingredients were prepared according to the formula of Comparative Example 2.

[0050] Comparative Example 8: Referring to Example 6, the ingredients were prepared according to the formula of Comparative Example 3.

[0051] Comparative Example 9: Referring to Example 6, the ingredients were prepared according to the formula of Comparative Example 4.

[0052] Comparative Example 10: Referring to Example 7, the ingredients were prepared according to the formula of Comparative Example 5.

[0053] The ionic conductivity of Examples 5, 6, and 7, and Comparative Examples 6, 7, 8, 9, and 10 was tested.

[0054]

[0055] It should be noted that those skilled in the art can make various modifications to this invention without departing from its principles, and these modifications and improvements also fall within the scope of protection of the claims of this invention.

Claims

1. A polyoxymethylene-based halide composite solid electrolyte, characterized in that, It includes polyoxymethylene, lithium / sodium salt, halide, plasticizer and organic solvent; the mass ratio of polyoxymethylene, lithium / sodium salt, halide, plasticizer and organic solvent is 1:0.08~2:0.001~0.55:0.01~1:6~120.

2. The polyoxymethylene-based halide composite solid electrolyte according to claim 1, characterized in that, The molecular weight of the polyoxymethylene is 500 to 5,000,000.

3. The polyoxymethylene-based halide composite solid electrolyte according to claim 1, characterized in that, The lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2), lithium borate (LiBOB), lithium difluorooxalate borate (LiDFOB), lithium tetrafluorooxalate phosphate (LiPF4(C2O4)), lithium hexafluorophosphate (LiPF6), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), and lithium perchlorate (LiClO4); The sodium salt includes at least one of sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium bis(fluorosulfonyl)imide (NaFSI), sodium tetrafluoroborate (NaBF4), sodium difluorophosphate (NaPO2F2), sodium borate (NaBOB), sodium difluorooxalate borate (NaDFOB), sodium tetrafluorooxalate phosphate (NaPF4(C2O4)), sodium hexafluorophosphate (NaPF6), sodium chloride (NaCl), sodium bromide (NaBr), sodium iodide (NaI), and sodium perchlorate (NaClO4).

4. The polyoxymethylene-based halide composite solid electrolyte according to claim 1, characterized in that, The plasticizer includes at least one of succinic anhydride, glutaronitrile, adiponitrile, 2-methylsuccinic anhydride, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 15-crown-5-ether, 18-crown-6-ether, 1,3-dioxolane, ethylene carbonate, dimethyl carbonate, propylene carbonate, diethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, and 1,3-propanesulfonate lactone.

5. The polyoxymethylene-based halide composite solid electrolyte according to claim 1, characterized in that, The general chemical formula of the halide is AxByCz or AxByOCz, where x > 0, y > 0, z > 0; A is selected from Li + Na + One of them; B is selected from Cr 3+ V 3+ Fe 3+ Co 3+ Ni 3+ Ti 3+ ,Sc 3+ Lu 3+ Y 3+ Al 3+ Ga 3+ In 3+ Yb 3+ Tm 3+ Er 3+ Ho 3+ Dy 3+ 、Tb 3+ Gd 3+ Eu 3+ 、Sm 3+ Pm 3+ 、Nd 3+ Pr 3+ Ce 3+ La 3+ Be 2+ Mg 2+ Ca 2+ Cu 2+ Zn 2+ 、Sr 2+ Cd 2+ Pb 2+ Ba 2+ Ti 4 + Zr 4+ Hf 4+ Sn 4+ 、Ge 4+ Si 4+ 、Nb 5+ Ta 5+ At least one of them; C is selected from At least one of them.

6. The polyoxymethylene-based halide composite solid electrolyte according to claim 1, characterized in that, The organic solvent includes at least one of N-methylpyrrolidone, tetrahydrofuran, dichloromethane, acetone, dimethylformamide, methyl ethyl ketone, chloroform, 1,4-dioxane, toluene, benzene, dimethyl sulfoxide, and sulfolane.

7. A method for preparing a polyoxymethylene-based halide composite solid electrolyte as described in any one of claims 1 to 6, characterized in that, The preparation method is a solvent blending and drying film-forming process, including the following steps: (1) Preparation of polymer solution: Take materials according to the formula, and mix polyoxymethylene and organic solvent at 155~190 °C to prepare polymer solution; (2) Preparation of solid electrolyte slurry: The polymer solution, lithium / sodium salt, halide and plasticizer are ground at 155~190 ℃ for 1~10 min to prepare solid electrolyte slurry; (3) Preparation of solid electrolyte: The solid electrolyte slurry is uniformly coated on a substrate that can withstand a temperature of 200 ℃ and dried at 155~190 ℃ for 0.1~3 h to prepare polyoxymethylene halide composite solid electrolyte.

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