Polymer solid-state battery and preparation method thereof

Abstract

The invention relates to a preparation method of a polymer solid-state battery. The preparation method comprises the following steps: adding a high-voltage matrix monomer, a flame-retardant monomer, a first conductive lithium salt and a first initiator into a first organic solvent, and mixing to obtain an electrolyte precursor solution A; adding a flexible matrix monomer, a high-transference-number filler, a second conductive lithium salt, a functional auxiliary agent and a second initiator into a second organic solvent, and mixing to obtain an electrolyte precursor solution B; coating the electrolyte precursor solution A on the surface of the positive electrode and then preparing a high-voltage flame-retardant layer through in-situ polymerization reaction; coating the electrolyte precursor solution B on the surface of the high-voltage flame-retardant layer, and then stacking and assembling the high-voltage flame-retardant layer and a negative electrode layer to form a battery; and performing in-situ polymerization reaction on the electrolyte precursor solution B to prepare the interface layer with high migration number. The polymer solid-state battery prepared by the preparation method disclosed by the invention has antioxidant stability and inherent flame retardance under high potential (greater than or equal to 5V).

Description

Technical Field

[0001] This application relates to the field of all-solid-state battery technology, specifically to a polymer solid-state battery and a method for preparing the polymer solid-state battery. Background Technology

[0002] This section provides background information relevant to this application, which does not necessarily constitute prior art.

[0003] Traditional lithium-ion batteries use liquid electrolytes, which pose safety hazards such as volatility, flammability, and leakage, severely limiting their adoption in high-power, high-safety applications. Especially with the continuous improvement of energy density, lithium-ion batteries using organic liquid electrolytes may pose risks of fire or even explosion during operation. Solid-state batteries (SSBs), by using solid-state electrolytes (SSEs) to completely replace traditional liquid electrolytes and separators, effectively avoid these risks. Existing solid-state battery electrolyte materials include: oxide electrolytes (such as LLZO, LLTO, etc.), sulfide electrolytes (such as LPS, LPSCl, etc.), and polymer electrolytes (such as PEO, etc.).

[0004] Traditional lithium-ion batteries use liquid electrolytes that can flow and form a perfect liquid-solid contact with electrode particles. In contrast, solid-state batteries have a solid-solid contact between the solid electrolyte and the electrode, resulting in a small physical contact area, high interfacial impedance, and difficulty in penetrating the electrode pores like a liquid. This leads to a small effective contact area, limited ion transport channels, and a sharp increase in internal resistance and capacity decay. Under high voltage, the cathode material and solid electrolyte may undergo chemical / electrochemical side reactions, generating a high-resistance interfacial layer, further increasing ion transport resistance. During cycling, lithium ions are unevenly deposited on the anode surface, forming lithium dendrites. These solid-solid interface contact and stability issues limit the performance of solid-state batteries. Polymer solid-state batteries, with their flexible, easy-to-process, and good electrode contact properties, hold promise for solving the solid-solid interface contact problem in solid-state batteries.

[0005] However, existing polymer solid-state batteries have the following technical problems: (1) The mechanical strength of the solid electrolyte in polymer solid-state batteries is insufficient to consistently suppress dendrite growth, which may lead to dendrite penetration of the electrolyte and cause internal short circuits. The solid-solid interface contact and stability problem is the most critical obstacle restricting the performance of solid-state batteries; (2) The room temperature ionic conductivity of polymer electrolytes is low (usually <10). -5 (S / cm) and the lithium-ion transference number is generally lower than the ideal value (0.5); (3) the polymer electrolyte lacks inherent flame retardant design, which poses a safety hazard.

[0006] To improve the performance of polymer electrolytes, existing technical solutions include introducing ion-conducting additives, introducing plasticizers, using in-situ polymerization processes, and setting up multilayer composite structures. For example, Chinese patent CN107069085B discloses a method that improves polymer flexibility by introducing a nanoparticle-polymer network, but the room temperature ionic conductivity and lithium-ion transference number are low, making it difficult to meet the requirements of high-power charging and discharging. Chinese patent CN108963334B discloses a method that solves the interface stability problem of solid-state batteries by constructing a multilayer polymer electrolyte, but its preparation process is relatively complex, and the functional integration of the two-layer structure (such as high transference number and inherent flame retardancy) is not high. The stacking and interface preparation processes are complex, and the interlayer contact impedance is a new performance obstacle. Patent KR102024889B1 discloses a method that uses polyethylene oxide (PEO) as a matrix to form a polymer electrolyte through solvent evaporation and thermal curing, but it has problems such as poor thermal stability, the need for an additional vacuum drying step, and low ionic conductivity. Chinese patent CN114085325A discloses a method that uses polyvinylidene fluoride-polyhexafluoropropylene and polymerizable monomers containing ethylene oxide units to prepare an ion-conducting semi-interpenetrating network polymer, which improves the performance, but its preparation process is complex.

[0007] Therefore, there is an urgent need to develop a polymer solid-state battery with high room temperature ionic conductivity, low interfacial impedance, high lithium-ion transference number, good processability, and safety to meet the application requirements of stable and safe operation under high voltage. Summary of the Invention

[0008] This invention aims to provide a solid-state battery and its preparation method. The solid-state battery is a polymer solid-state battery with a flexible, multilayered, flame-retardant solid polymer electrolyte. A stepwise in-situ polymerization method is used to directly form a film on the electrodes, aiming to achieve high safety, high transport number, high voltage stability, and excellent interfacial compatibility through structural partitioning and component optimization. The solid-state battery prepared by the method provided by this invention achieves a tight "molecular-level" bond between the electrodes and the polymer electrolyte, significantly reducing interfacial impedance, significantly improving room-temperature ionic conductivity and lithium-ion transport number, while also maintaining good safety performance.

[0009] To achieve the above objectives, the technical solution adopted in this application is as follows: a solid-state battery, the solid-state battery comprising a structure assembled from a positive electrode, a high-voltage flame-retardant layer, a high-mobility-number interface layer and a negative electrode.

[0010] The high-pressure flame-retardant layer possesses high rigidity support and excellent ionic conductivity (>10). -4(S / cm), and can impart oxidation stability and inherent flame retardancy to the solid-state battery at high potentials (≥5V), widen the battery voltage window and enhance electrochemical stability, thereby improving battery safety performance.

[0011] The high mobility number interface layer is a flexible polymer layer that can fully contact the negative electrode, providing flexibility and effectively alleviating interface stress. This high mobility number interface layer significantly improves ion transport efficiency and battery rate performance, significantly reduces interface impedance, and can suppress lithium dendrite growth to prevent internal short circuits.

[0012] The polymer electrolyte composed of a high-pressure flame-retardant layer and a high-mobility-number interface layer can significantly improve room-temperature ionic conductivity and lithium-ion mobility, enhance interfacial mechanical strength and chemical stability, and effectively suppress interfacial degradation and side reactions during cycling.

[0013] On the other hand, the method for preparing the solid-state battery includes the following steps: The process of adding high-voltage matrix monomer, flame-retardant monomer, first conductive lithium salt and first initiator into a first organic solvent and mixing to obtain electrolyte precursor solution A; The process of adding flexible matrix monomer, high mobility number filler, second conductive lithium salt, functional additive and second initiator into second organic solvent to mix and obtain electrolyte precursor solution B; The process of coating electrolyte precursor solution A onto the surface of the positive electrode and then preparing a high-pressure flame-retardant layer by in-situ polymerization reaction; The process of coating the surface of the high-voltage flame-retardant layer with electrolyte precursor solution B and then stacking it with the negative electrode to assemble a battery; The process of preparing a high mobility number interface layer by in-situ polymerization of electrolyte precursor solution B.

[0014] The high-pressure matrix monomer is used to form a polymer backbone with high cross-linking density, providing high mechanical strength and antioxidant stability. Preferably, the high-pressure matrix monomer is at least one of trimethylolpropane triacrylate (TMPTA), pentaerythritol tetraacrylate (PETEA), and ethoxylated trimethylolpropane triacrylate (ETPTA).

[0015] The flame-retardant monomer introduces P / F / N elements into the electrolyte through chemical bonding, achieving inherent flame retardancy. Preferably, the flame-retardant monomer is a nitrogen-containing and / or fluorine-containing flame-retardant monomer. More preferably, the flame-retardant monomer is diethyl vinylphosphonate (DEVP) and / or phosphate methacrylate (MAP).

[0016] The first conductive lithium salt is used to provide lithium ions (Li). +Charge carriers. Preferably, the first conductive lithium salt is at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), and lithium bis(oxalate)borate (LiBOB).

[0017] In this process, the first initiator catalyzes the polymerization of monomers to form a solid network. Depending on the type of first initiator, the electrolyte precursor solution A can be photocured or thermocured.

[0018] In one or more embodiments, the first initiator is a photoinitiator, including free radical photoinitiators and / or cationic photoinitiators. For example, the photoinitiator may be selected from at least one of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone. After the electrolyte precursor solution A is coated onto the positive electrode surface, a high-pressure flame-retardant layer is obtained by photocuring. The photocuring parameters are: UV wavelength: 365-400 nm; irradiation intensity: 50-200 mW / cm². 2 Time: 10-60 seconds.

[0019] In one or more embodiments, the first initiator is a thermal initiator, including azo compounds and / or peroxides. For example, the thermal initiator is selected from at least one of azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), azobisisoheptanenitrile (ABVN), dimethyl azobisisobutyrate, ammonium persulfate, potassium persulfate, benzoyl peroxide (BPO), benzoyl tert-butyl peroxide (BPB), and methyl ethyl ketone peroxide. After the electrolyte precursor solution A is coated on the surface of the positive electrode, a high-pressure flame retardant layer is obtained by thermosetting. The thermosetting parameters are: temperature: 60-120℃; time: 1-3h.

[0020] The flexible matrix monomer is used to form a flexible cross-linked network, improving the interfacial wettability and mechanical flexibility of the electrolyte and electrode. Preferably, the flexible matrix monomer is at least one of polyethylene glycol dimethacrylate (PEGDMA), polyethylene glycol diacrylate (PEGDA), and polysiloxane-modified acrylate.

[0021] Among them, high mobility number fillers are achieved through the Li on their surface. + Affinity sites adsorb anions, decoupling ion movement and significantly increasing mobility numbers, while also providing mechanical support. For example, high mobility number fillers utilize ceramic fast lithium-ion conductors (ceramic fast lithium-ion conductors have an ionic conductivity ≥ 4 × 10⁻⁶). -4The substrate, consisting of a flexible cross-linked network formed by flexible matrix monomers, and filled with ceramic fast lithium-ion conductors, has a density of S / cm. This design ensures a good and uniform lithium-ion transport pathway, facilitating the uniform insertion and extraction of lithium on the electrode. It also provides good support and deformation capacity, mitigating volume changes while preventing damage to the high mobility number interface layer due to particle breakage or lithium dendrite precipitation. Preferably, the high mobility number filler is Li. 1.3 Al 0.3 T 1.7 (PO4)3(LATP) ceramic particles, Li7La3Zr2O 12 (LLZO), Li 6.75 La3Zr 1.75 Nb 0.25 O 12 (LLZNO), Li 6-x PS5Cl 1+x (LPSC, 0≤x≤1), Li 10 SnP2S 12 At least one of (LSPS), nano TiO2, and nano Al2O3.

[0022] The second conductive lithium salt provides lithium ions (Li). + Charge carriers. Preferably, the second conductive lithium salt is at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), and lithium bis(oxalate)borate (LiBOB).

[0023] The functional additive is preferably a plasticizer, which can lower the glass transition temperature of the elastic polymer, improve chain segment mobility and dielectric constant, and increase room temperature ionic conductivity. More preferably, the functional additive is succinate (SN) and / or adiponitrile (ADN).

[0024] The second initiator is used to catalyze the polymerization of monomers to form a solid network. In one or more embodiments, the second initiator is a thermal initiator, and in one or more embodiments, the thermal initiator is selected from at least one of azobisisobutyronitrile (AIBN), azobisisovalerate (ABVN), and benzoyl peroxide (BPO). The electrolyte precursor solution B is cured by hot pressing, and the parameters for hot pressing are: temperature: 50-80℃; time: 2-6h; pressure: 0.1-1MPa.

[0025] The first organic solvent and the second organic solvent each independently include at least one selected from ethylene carbonate, propylene carbonate, N-methylpyrrolidone, tetrahydrofuran, ethylene glycol dimethyl ether, acetonitrile, anisole, and p-xylene. Preferably, the first organic solvent is acetonitrile or acetone, and the second organic solvent is acetonitrile or acetone.

[0026] In one or more embodiments, the electrolyte precursor solution A comprises the following components in parts by weight: 40-60 parts by weight of high-pressure matrix monomer; 15-30 parts by weight of flame retardant monomer; 20-30 parts by weight of the first conductive lithium salt; 0.1-1.5 parts by weight of the first initiator; 100-150 parts by weight of the first organic solvent.

[0027] In one or more embodiments, the electrolyte precursor solution B comprises the following components in parts by weight: 40-60 parts by weight of flexible matrix monomer; 10-30 parts by weight of high migration number fillers; 20-30 parts by weight of the second conductive lithium salt; 0-15 parts by weight of functional additives; 0.1-1.5 parts by weight of the second initiator; 100-150 parts by weight of a second organic solvent.

[0028] In one or more embodiments, the coating thickness of the electrolyte precursor solution B on the surface of the high-pressure flame retardant layer ranges from 5 to 25 μm.

[0029] In one or more embodiments, the positive electrode includes a positive electrode current collector and a positive electrode active material layer disposed on both sides of the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material, a conductive agent, and a binder. The conductive agent includes, but is not limited to, one or more of conductive carbon black, SuperP, acetylene black, Ketjen black, carbon nanofibers, and carbon nanotubes. The binder includes, but is not limited to, one or more of polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC-Na), polyvinylpyrrolidone, polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), hydrogenated nitrile butadiene rubber (HNBR), polyacrylic acid (PAA), lithium polyacrylate (PAA-Li), hydrogenated styrene-butadiene block copolymer (SEBS), and polyisobutylene (PIB). The positive electrode active material includes, but is not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium manganese oxide, nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium iron phosphate, lithium iron-manganese phosphate, and lithium-rich manganese-based materials.

[0030] In one or more embodiments, the negative electrode is one of lithium metal, lithium alloy, silver-carbon negative electrode, magnesium-carbon negative electrode, copper foil, and carbon-coated copper foil.

[0031] In one or more embodiments, the thickness of the high-voltage flame-retardant layer is 1-4.5 μm and the thickness of the high mobility number interface layer is 0.5-1 μm. When the thickness is controlled within the above range, the battery safety performance, the performance of volume change during absorption cycling, and the lithium-ion conductivity can be balanced simultaneously.

[0032] The preparation method provided by this invention employs a stepwise in-situ polymerization process. Pre-curing of the high-pressure flame-retardant layer maintains high-pressure stability; in-situ polymerization of the high-mobility-number interface layer ensures interfacial contact, forming a highly wetted and tightly contacted solid-solid interface. The preparation method provided by this invention can produce high-safety, high-rate all-solid-state lithium metal batteries.

[0033] Compared with the prior art, the beneficial effects of this application are: 1. High inherent safety: It adopts a fully solid-state structure without liquid electrolyte, combined with the chemical integration of inherent flame-retardant components (such as phosphorus-containing monomers), which completely eliminates safety hazards; 2. High-performance lithium-ion transport: The second layer introduces fillers with high lithium-ion affinity (especially ceramic fast lithium-ion conductors) to induce the polymer matrix to form fast transport channels and effectively decouple the movement of lithium ions and anions, increasing the lithium-ion transference number to ≥0.5, which greatly improves the charge and discharge rate and power density of the battery. 3. Excellent interface compatibility: The multi-layer structure design successfully solves the contradiction between the oxidation resistance of the high-voltage positive electrode and the reduction resistance / inhibition of lithium dendrites of the lithium metal negative electrode, effectively extending the cycle life of the solid-state battery. 4. Simple process and low interface impedance: Stepwise in-situ polymerization technology can utilize liquid monomers to wet electrode pores, and after polymerization, a tightly connected solid-solid interface is formed, which effectively reduces the interface contact resistance in traditional solid-state battery assembly.

[0034] The following description is based on specific embodiments. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the all-solid-state battery structure of Embodiment 1 of the present invention.

[0036] In the attached figures, the following labels are used: 1-Positive electrode current collector; 2-Positive electrode active material layer; 3-High voltage flame retardant layer; 4-Ceramic fast lithium-ion conductor; 5-High mobility number interface layer; 6-Lithium metal sheet. Detailed Implementation

[0037] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0038] It should be noted that the raw material components described in the embodiments of the present invention are all commercially available products.

[0039] [Example 1] This embodiment provides an all-solid-state battery, with the structure as follows: Figure 1 As shown, the negative electrode of this all-solid-state battery is a lithium metal sheet 6, and a polymer electrolyte is disposed between the lithium metal sheet 6 and the positive electrode. The positive electrode includes a positive current collector 1 and a positive active material layer 2 (mainly composed of LiCoO2) disposed on the surface of the positive current collector 1. The polymer electrolyte includes a composite high-voltage flame-retardant layer 3 and a high mobility number interface layer 5, and the high mobility number interface layer 5 contains a ceramic fast lithium-ion conductor 4.

[0040] The method for preparing an all-solid-state battery provided in this embodiment includes the following steps: Step 1: As shown in Table 1, add the high-voltage matrix monomer, flame-retardant monomer, first conductive lithium salt and first initiator to the first organic solvent and mix to obtain electrolyte precursor solution A; Step 2: As shown in Table 1, add the flexible matrix monomer, high mobility number filler, second conductive lithium salt, functional additive and second initiator to the second organic solvent, and ultrasonically disperse for 30 min to obtain electrolyte precursor solution B; Step 3: After coating the electrolyte precursor solution A onto the surface of the positive electrode, the high-pressure flame retardant layer is obtained by irradiating it under 365nm UV light for 30s through in-situ polymerization reaction. Step 4: Coat the electrolyte precursor solution B onto the high-voltage flame-retardant layer, then attach it to the negative electrode and stack them to assemble the battery. Step 5: The assembled battery is thermally cured at 50°C for 6 hours, and a high mobility number interface layer is obtained through in-situ polymerization reaction to obtain an all-solid-state battery.

[0041] Table 1

[0042] [Example 2] This embodiment provides an all-solid-state battery, whose positive and negative electrodes are the same as those in Embodiment 1.

[0043] The fabrication method of this all-solid-state battery includes the following steps: Step 1: As shown in Table 2, add the high-voltage matrix monomer, flame-retardant monomer, first conductive lithium salt and first initiator to the first organic solvent and mix to obtain electrolyte precursor solution A; Step 2: As shown in Table 2, add the flexible matrix monomer, high mobility number filler, second conductive lithium salt, functional additive and second initiator to the second organic solvent and ultrasonically disperse for 1 hour to obtain electrolyte precursor solution B; Step 3: After coating the electrolyte precursor solution A onto the surface of the positive electrode, the high-pressure flame retardant layer is obtained by irradiating it under 365nm UV light for 30s through in-situ polymerization reaction. Step 4: Coat the electrolyte precursor solution B onto the high-voltage flame-retardant layer, then attach it to the negative electrode and stack them to assemble the battery. Step 5: The assembled battery is thermally cured at 80°C for 2 hours. A high mobility number interface layer is obtained through in-situ polymerization reaction, resulting in an all-solid-state battery.

[0044] Table 2

[0045] [Example 3] This embodiment provides an all-solid-state battery, whose positive and negative electrodes are the same as those in Embodiment 1.

[0046] The fabrication method of this all-solid-state battery includes the following steps: Step 1: As shown in Table 3, add the high-voltage matrix monomer, flame-retardant monomer, first conductive lithium salt and first initiator to the first organic solvent and mix to obtain electrolyte precursor solution A; Step 2: As shown in Table 3, add the flexible matrix monomer, high mobility number filler, second conductive lithium salt, functional additive and second initiator to the second organic solvent and ultrasonically disperse for 40 min to obtain electrolyte precursor solution B; Step 3: After coating the electrolyte precursor solution A onto the surface of the positive electrode, the high-pressure flame retardant layer is obtained by irradiating it under 365nm UV light for 30s through in-situ polymerization reaction. Step 4: Coat the electrolyte precursor solution B onto the high-voltage flame-retardant layer, then attach it to the negative electrode and stack them to assemble the battery. Step 5: The assembled battery is thermally cured at 60°C for 4 hours, and a high mobility number interface layer is obtained through in-situ polymerization reaction to obtain an all-solid-state battery.

[0047] Table 3

[0048] [Comparative Example 1] This comparative example provides an all-solid-state battery, whose positive and negative electrodes are the same as those in Example 1.

[0049] The preparation method of the all-solid-state battery includes the following steps: dissolving 70 parts by mass of PEO (CAS No.: 25322-68-3) and 30 parts by mass of LiTFSI (CAS No.: 90076-65-6) in 120 parts by mass of organic solvent ACN, casting the mixture into a film, drying it, and then hot-pressing it (80℃, 0.5MPa) between the positive and negative electrodes.

[0050] [Comparative Example 2] This comparative example provides an all-solid-state battery, whose positive and negative electrodes are the same as those in Example 1.

[0051] The fabrication method of this all-solid-state battery includes the following steps: Step 1: As shown in Table 4, mix the flexible matrix monomer, flame retardant monomer, conductive lithium salt, initiator and organic solvent to obtain the electrolyte precursor solution. Step 2: Take a polypropylene (PP) / polyethylene (PE) composite membrane, wet the pores of the composite membrane with an electrolyte precursor solution, and then perform in-situ thermosetting (60℃, 4h) to obtain a solid electrolyte material. Step 3: Assemble the battery by stacking it in the order of positive electrode / solid electrolyte material / negative electrode, and let it stand at 80°C for 24 hours to obtain an all-solid-state battery.

[0052] Table 4

[0053] [Comparative Test] Electrochemical performance and safety tests were conducted on the all-solid-state batteries provided in Examples 1-3 and Comparative Examples 1-2, and the results are shown in Table 5.

[0054] Table 5

[0055] According to the test results shown in Table 5, the polymer electrolyte composed of a high-pressure flame-retardant layer and a high-mobility-number interface layer can significantly improve the room-temperature ionic conductivity and lithium-ion mobility number of solid-state batteries, enhance the interfacial mechanical strength and chemical stability, effectively suppress interfacial degradation and side reactions during cycling, and has excellent flame-retardant properties.

[0056] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a polymer solid-state battery, characterized in that, The process includes the following steps: The process of adding high-voltage matrix monomer, flame-retardant monomer, first conductive lithium salt and first initiator into a first organic solvent and mixing to obtain electrolyte precursor solution A; The process of adding flexible matrix monomer, high mobility number filler, second conductive lithium salt, functional additive and second initiator into second organic solvent to mix and obtain electrolyte precursor solution B; The process of coating electrolyte precursor solution A onto the surface of the positive electrode and then preparing a high-pressure flame-retardant layer by in-situ polymerization reaction; The process of coating the surface of the high-voltage flame-retardant layer with electrolyte precursor solution B and then stacking it with the negative electrode to assemble a battery; The process of preparing a high mobility number interface layer by in-situ polymerization of electrolyte precursor solution B; The flame-retardant monomer is a nitrogen-containing and / or fluorine-containing flame-retardant monomer; The first initiator is a photoinitiator or a thermal initiator, and the second initiator is a thermal initiator.

2. The preparation method according to claim 1, characterized in that, The high-pressure matrix monomer is at least one of trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and ethoxylated trimethylolpropane triacrylate.

3. The preparation method according to claim 1, characterized in that, The flame-retardant monomer is diethyl vinylphosphonate and / or phosphate methacrylate.

4. The preparation method according to claim 1, characterized in that, The flexible matrix monomer is at least one of polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, and polysiloxane-modified acrylate.

5. The preparation method according to claim 1, characterized in that, The high mobility number filler is at least one of LATP ceramic particles, LLZO, LLZNO, LPSC, LSPS, nano TiO2, and nano Al2O3.

6. The preparation method according to claim 1, characterized in that, The first conductive lithium salt and the second conductive lithium salt each independently include at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, and lithium bis(oxalate)borate.

7. The preparation method according to claim 1, characterized in that, The first organic solvent and the second organic solvent each independently include at least one of ethylene carbonate, propylene carbonate, N-methylpyrrolidone, tetrahydrofuran, ethylene glycol dimethyl ether, acetonitrile, anisole, and p-xylene.

8. The preparation method according to claim 1, characterized in that, The functional additive is a plasticizer.

9. The preparation method according to claim 1, characterized in that, The electrolyte precursor solution A comprises the following components in parts by weight: 40-60 parts by weight of high-pressure matrix monomer, 15-30 parts by weight of flame-retardant monomer, 20-30 parts by weight of first conductive lithium salt, 0.1-1.5 parts by weight of first initiator, and 100-150 parts by weight of first organic solvent. The electrolyte precursor solution B comprises the following components in parts by weight: 40-60 parts by weight of flexible matrix monomer, 10-30 parts by weight of high mobility number filler, 20-30 parts by weight of second conductive lithium salt, 0-15 parts by weight of functional additive, 0.1-1.5 parts by weight of second initiator, and 100-150 parts by weight of second organic solvent.

10. The polymer solid-state battery prepared by the preparation method according to any one of claims 1-9, characterized in that, The polymer solid-state battery comprises a structure assembled from a positive electrode, a high-voltage flame-retardant layer, a high-mobility-number interface layer, and a negative electrode.

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