In-situ solid-state battery and preparation method thereof

Abstract

The preparation method comprises the following steps: injecting pre-solid liquid added with an organic phosphorus fluorine compound into a battery cell, carrying out vacuum sealing, standing and infiltrating at a relatively high temperature, heating the organic phosphorus fluorine compound to decompose a small amount of phosphorus and fluorine free radicals, capturing a small amount of free radicals decomposed by an initiator, and preventing monomers from polymerizing, so as to obtain the in-situ solid-state battery. Enabling the pre-solid liquid to quickly and efficiently infiltrate the battery cell at the temperature; and heating the uniformly infiltrated battery cell at a higher temperature, decomposing the initiator to generate a large amount of free radicals, at the moment, completely consuming a small amount of fluorine and phosphorus free radicals so as not to prevent polymerization, polymerizing the pre-solid liquid in the battery cell and curing in situ, thereby completing the preparation of the in-situ solid-state battery. According to the invention, the infiltration efficiency of the pre-solid liquid during preparation of the in-situ solid-state battery is greatly improved; the cured electrolyte has a flame-retardant effect, and the in-situ solid-state battery is endowed with higher safety performance; the quality guarantee period of the pre-solid-liquid at room temperature is greatly prolonged, and the storage and transportation cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery technology, and more specifically, this invention relates to an in-situ solid-state battery and its preparation method. Background Technology

[0002] In recent years, with the increasing market share of new energy electric vehicles, spontaneous combustion incidents involving electric vehicles have become increasingly frequent. In the first half of 2022 alone, there were as many as 47 publicly reported cases of spontaneous combustion of new energy vehicles, equivalent to about one new energy vehicle catching fire every five days. This has raised significant public concern. The main reason is that the electrolyte in the lithium-ion batteries currently used in electric vehicles is an organic solvent, characterized by high volatility, low flash point, and easy leakage. It is flammable and explosive at high temperatures. Therefore, when the power battery is subjected to abuse conditions such as overcharging, collision, compression, or short circuits, it is prone to ignition or even explosion, leading to spontaneous combustion of new energy vehicles. Furthermore, severe side reactions in high-energy-density positive and negative electrode material systems result in rapid capacity decay and poor cycle performance. Therefore, liquid lithium batteries have approached their energy density limit and it is difficult to further improve it. This also makes it difficult to further increase the driving range of electric vehicles. Therefore, there is an urgent need to introduce new battery technologies for iterative upgrades of liquid batteries.

[0003] In-situ solidification technology can solidify the electrolyte inside a lithium-ion battery in situ, thus creating an in-situ solid-state battery. This not only improves the thermal stability of lithium-ion batteries, reducing the risk of thermal runaway, but also makes them more compatible with high-specific-capacity positive and negative electrode material systems, enabling the fabrication of high-energy-density lithium-ion batteries. Currently, the main method for preparing in-situ solid-state batteries involves adding a small amount of polymer monomers and initiators to the electrolyte, then heating it to decompose the initiator and generate free radicals. These free radicals then initiate the polymerization of monomers into a polymer network, locking the electrolyte immersed in the lithium-ion battery in situ, thereby solidifying the electrolyte. This not only improves the safety of lithium-ion batteries but also provides better cycle stability.

[0004] However, the decomposition temperatures of initiators currently suitable for in-situ solid-state battery fabrication are generally between 30 and 80°C. This limits the use of low temperatures and prolonged settling times during the fabrication process to ensure adequate electrolyte wetting of the lithium-ion battery before solidification. However, at low temperatures, the electrolyte's wetting effect on the lithium-ion battery is poor. Extending the settling time not only has limited effect on improving battery wetting but also significantly increases the fabrication time and cost of in-situ solid-state batteries. Furthermore, ester-based organic electrolytes remain flammable after solidification, posing a significant safety hazard to currently fabricated in-situ solid-state batteries. Therefore, there is an urgent need for a method to improve the wettability of in-situ solid-state batteries and the flame retardancy of in-situ solidified electrolytes. Summary of the Invention

[0005] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0006] To achieve these and other advantages according to the present invention, the present invention provides a method for preparing an in-situ solid-state battery, comprising: first adding an organophosphorus fluorine compound as a polymerization inhibitor to a pre-solidified liquid, injecting the pre-solidified liquid into a battery cell, allowing the pre-solidified liquid to fully wet the battery cell under temperature A, and then curing the battery cell uniformly wetted by the pre-solidified liquid at temperature B to prepare an in-situ solid-state battery; wherein temperature B is higher than temperature A.

[0007] Preferably, the organophosphorus fluorine compound comprises any one or more of ethoxy(pentafluoro)cyclotriphosphazene, pentafluoro(phenoxy)cyclotriphosphazene, and hexa(2,2,2-trifluoroethoxy)cyclotriphosphazene; The organophosphorus fluorine compound accounts for 3% to 7% of the mass of the pre-solidified liquid.

[0008] Preferably, the temperature of A is 35~45℃, and the immersion time of the battery cell is 12~24h; The temperature of B is 60~65℃, and the curing time is 12~24h.

[0009] Preferably, the pre-solidified liquid further includes a carbonate-based electrolyte, a small molecule monomer, and an initiator.

[0010] Preferably, the carbonate-based electrolyte comprises a lithium salt and a carbonate solvent.

[0011] The concentration of lithium salt in the carbonate-based electrolyte is 1~1.5 mol / L; The carbonate-based electrolyte accounts for 78% to 92% of the mass of the prepared presolid solution; The lithium salt includes any one or more of lithium hexafluorophosphate, lithium bis(difluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(oxalateborate), and lithium difluorooxalateborate. The carbonate solvent is a mixed solution of ethylene carbonate and methyl ethyl carbonate, with a mass ratio of ethylene carbonate to methyl ethyl carbonate of 3:7.

[0012] Preferably, the small molecule monomer is a small molecule monomer having one or more carbon-carbon double bonds; The mass ratio of the small molecule monomer in the pre-solidified liquid is 5%~15%; The small molecule monomers specifically include any one or more of the following: methyl methacrylate, methoxy polyethylene glycol acrylate, methyl acrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate.

[0013] Preferably, the initiator is an initiator with a half-life of 10 hours and a decomposition temperature of 60°C or higher. The initiator accounts for 0.5% to 2% of the mass of the small molecule monomer; The initiator includes any one or more of azobisisobutyronitrile, azobisisovalerate, dimethyl azobisisobutyrate, and lauroyl peroxide.

[0014] Preferably, the method for preparing the pre-solidified liquid includes: In an argon-filled glove box, lithium salts are added to carbonate solvents and stirred until homogeneous to prepare a carbonate-based electrolyte. Small molecule monomers, initiators, organophosphorus and fluorine compounds, and carbonate-based electrolytes are stirred in proportion to prepare a pre-solidified solution.

[0015] Preferably, the method for wetting the battery cell after injecting the pre-solidifying liquid specifically includes: Vacuum sealing of the electrolyte-filled cells is performed using a pre-sealing machine with a dew point temperature ≤-50℃, a vacuum degree ≤-95kPa, and a temperature of 180℃. The cells are then placed in an oven at 35~45℃ and left to stand for 12~24 hours to allow the pre-solidified liquid to fully wet the cells.

[0016] The battery cell includes an NCM911 positive electrode, a silicon-carbon 450 negative electrode, and a ceramic separator stack, and the designed capacity of the battery cell is 1A.

[0017] When organophosphorus fluorine compounds are heated at this temperature, they decompose to release small amounts of phosphorus and fluorine free radicals. These free radicals can effectively capture the small amounts of initiator free radicals and monomer free radicals released by the monomers and initiators when heated at 35-45°C, thereby preventing the chain growth polymerization reaction between monomer free radicals. The specific mechanism of action is as follows: The polymerization and curing reaction that occurs at 35℃~45℃ without the addition of organophosphorus fluorine compounds: (1) First, initiator I homolytically cleaves into a pair of primary free radicals 2R. * : I→2R * (2) Primary free radical R * With monomer Addition, generating monomeric free radicals : Wherein, X is one of H, halogen atom, alkyl, alkoxy, ester group, cyano group, carboxyl group, and amide group; (3) The generated monomeric free radicals and monomers Combine to generate chain free radicals This process is repeated to form polymer molecules. : The polymerization inhibition reaction that occurs at 35℃~45℃ when organophosphorus and fluorine compounds are present: (1) Initiator I homolytically cleaves into a pair of primary free radicals 2R * : I→2R * (2) Primary free radical R * With monomer Addition, generating monomeric free radicals : (3) The generated primary free radicals (R * ) / Single free radical and phosphorus / fluorine radicals ([P]) * / [F] * The reaction generates stable compounds that prevent polymerization and solidification. R * +[P] * / [F] * →R[P] / [F] Therefore, the aforementioned battery cells containing organophosphorus fluoride compounds will not solidify during the high-temperature static process. This impregnation method allows battery cells filled with pre-solidified liquid to be impregnated at high temperatures without solidification, thereby greatly improving the impregnation effect of in-situ solidified batteries.

[0018] Subsequently, the uniformly impregnated battery cell is heated in an oven at 60-65°C for 12-24 hours. The initiator decomposes, generating a large number of free radicals. The small amount of fluorine / phosphorus free radicals are completely consumed and cannot prevent polymerization. The pre-solidified liquid in the battery cell polymerizes and solidifies in situ, thus completing the in-situ solid-state battery fabrication. Furthermore, organophosphorus fluorine compounds are commonly used flame-retardant electrolyte additives. At higher temperatures, they decompose to generate a large number of fluorine / phosphorus free radicals. These free radicals can capture active free radicals (such as H+) generated during the decomposition of the in-situ solidified electrolyte at high temperatures. . HO . This invention achieves a flame-retardant effect by interrupting the combustion chain reaction. Therefore, by adding organophosphorus fluoride compounds, the invention simultaneously achieves efficient and uniform wetting of the pre-solidified liquid in the cell without affecting the curing effect, and also gives the in-situ cured electrolyte a flame-retardant function, further enhancing the safety performance of the in-situ solid-state battery. Through the above method, an in-situ solid-state battery with high wettability and high safety can be prepared.

[0019] An in-situ solid-state battery is prepared by the above-described method for preparing an in-situ solid-state battery.

[0020] This invention offers at least the following advantages: First, the initiator used in current in-situ solid-state battery fabrication typically begins to decompose and initiate monomer curing at around 30°C. Therefore, the impregnation process in in-situ solid-state battery fabrication can only utilize room temperature (25°C) or lower, and requires prolonged standing (increasing the standing temperature would cause the pre-solidified liquid to solidify before the cell is properly impregnated, leading to uneven cell curing and deterioration of the in-situ solid-state battery's electrical performance). Such an impregnation process not only has poor impregnation effects but also is time-consuming and costly. This invention, however, utilizes the principle of organophosphorus fluorine compounds to capture free radicals and inhibit polymerization. By adding a small amount of organophosphorus fluorine compounds as additives to the pre-solidified liquid... The pre-wetting cells can be left to stand in an oven at 35-45℃ for 12-24 hours. This allows the cells to be fully and efficiently wetted by the pre-wetting solution without solidification. Then, the wetted cells are heated at 60-65℃. At this temperature, the initiator decomposes, generating a large number of free radicals, while the small amount of fluorine / phosphorus free radicals are completely consumed and cannot prevent polymerization. Therefore, the pre-wetting solution in the cells can solidify normally, thus preparing an in-situ solid-state battery. Because the pre-wetting solution has uniformly wetted the cells before solidification, a more uniformly solidified in-situ solid-state battery can be prepared. This greatly improves the wetting efficiency during the preparation of in-situ solid-state batteries and endows them with better electrochemical performance. Furthermore, organophosphorus fluorine compounds are excellent flame retardant additives, which can give the in-situ solidified electrolyte a good flame retardant effect, further improving the safety performance of the in-situ solid-state battery. Finally, the pre-solidified liquid currently undergoes slow solidification at room temperature, resulting in a short shelf life. It requires low-temperature storage and transportation, which greatly limits large-scale production and increases costs. However, adding a small amount of organophosphorus fluorine compounds can effectively prevent the pre-solidified liquid from polymerizing and solidifying at room temperature, thereby greatly increasing the shelf life of the pre-solidified liquid at room temperature and reducing storage and transportation costs.

[0021] In summary, this invention achieves three beneficial effects by adding a small amount of organophosphorus fluorine compound as an additive to the pre-solidified liquid: First, it greatly improves the wetting efficiency of the pre-solidified liquid during the preparation of in-situ solid-state batteries; second, it gives the solidified electrolyte a flame-retardant effect, giving the in-situ solid-state battery higher safety performance; and third, it greatly extends the shelf life of the pre-solidified liquid at room temperature, reducing storage and transportation costs.

[0022] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0023] Figure 1 The charge-discharge curve of the in-situ solid-state battery prepared in Example 3; Figure 2The capacity retention rates of in-situ solid-state batteries prepared in Example 5 and Comparative Examples 4 and 5 at different charge-discharge rates; Figure 3 The capacity retention rate of the in-situ solid-state batteries prepared in Example 4 and Comparative Example 6 at different charge-discharge rates. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0025] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof. Example 1: A method for preparing a pre-solidified liquid includes the following steps: In a glove box, LiPF6 was dissolved in a solution composed of ethylene carbonate and methyl ethyl carbonate (mass ratio of ethylene carbonate to methyl ethyl carbonate 3:7) to prepare a 1.2 mol / L LiPF6 electrolyte. According to the mass percentage, weigh 82% of LiPF6 electrolyte, 12% of methyl methacrylate monomer, 3% of pentaerythritol triacrylate monomer and 3% of ethoxy(pentafluoro)cyclotriphosphazene, mix them evenly, and then add 2% of azobisisovalerate initiator according to the total mass of methyl methacrylate monomer and pentaerythritol triacrylate monomer. After stirring evenly, prepare a pre-solidified liquid. Take 2 ml of the above pre-solidified liquid and put it into a 10 ml glass bottle. Seal the bottle in an argon atmosphere glove box. After standing at 45°C for 12 hours, the pre-solidified liquid in the glass bottle did not solidify. After standing at 45°C for 24 hours, the pre-solidified liquid in the glass bottle still did not show obvious solidification. After the temperature was raised to 60°C and stood for 12 hours, 80% of the pre-solidified liquid in the glass bottle solidified. After standing at 60°C for 24 hours, 100% of the pre-solidified liquid in the glass bottle solidified.

[0026] The above results demonstrate that the 3% ethoxy(pentafluoro)cyclotriphosphazene additive effectively prevents the polymerization and curing of the pre-solidified solution when it is left to stand at 45℃ for 24 hours. After curing at 60℃ for 24 hours, the pre-solidified solution can be completely cured. Furthermore, the cured electrolyte exhibits excellent flame retardant properties in ignition tests. This indicates that the pre-solidified solution with the 3% ethoxy(pentafluoro)cyclotriphosphazene additive can efficiently wet the electrolyte at 45℃ for 24 hours in the in-situ solid-state battery preparation process.

[0027] Example 2: A method for preparing a pre-solidified liquid includes the following steps: In a glove box, LiPF6 was dissolved in a solution composed of ethylene carbonate and methyl ethyl carbonate (mass ratio of ethylene carbonate to methyl ethyl carbonate 3:7) to prepare a 1.2 mol / L LiPF6 electrolyte. Weigh out 78% of LiPF6 electrolyte, 12% of methoxy polyethylene glycol acrylate, 3% of trimethylolpropane trimethacrylate monomer and 7% of ethoxy (pentafluoro)cyclotriphosphazene according to the mass percentage, mix them evenly, and then add 0.5% of azobisisobutyronitrile initiator according to the total mass of methoxy polyethylene glycol acrylate monomer and trimethylolpropane trimethacrylate monomer. Stir evenly to prepare a pre-solidified liquid. Take 2 ml of the above pre-cured liquid and put it into a 10 ml glass bottle. Seal the bottle in an argon atmosphere glove box. After the sealed glass bottle is placed at 35°C for 12 hours, the pre-cured liquid in the glass bottle does not solidify. After standing at 35°C for 24 hours, the pre-cured liquid in the glass bottle still does not show obvious solidification. After the temperature is raised to 65°C and the bottle is left to stand for 12 hours, the pre-cured liquid in the glass bottle has completely solidified.

[0028] The above results demonstrate that the 7% ethoxy(pentafluoro)cyclotriphosphazene additive effectively prevents the pre-solidified solution from polymerizing and curing after standing at 35℃ for 24 hours. After curing at 65℃ for 12 hours, the pre-solidified solution can then be completely cured. Furthermore, the cured electrolyte failed to ignite during the ignition test, exhibiting non-flammable properties. This indicates that the pre-solidified solution with 7% ethoxy(pentafluoro)cyclotriphosphazene additive can efficiently wet the electrolyte for 24 hours at 35℃ in the in-situ solid-state battery preparation process.

[0029] Example 3: A method for preparing an in-situ solid-state battery includes the following steps: The pre-solidified liquid prepared in Example 1 was injected into a pre-prepared 1Ah soft-pack battery cell (positive electrode: NCM911, negative electrode: silicon carbide 450, separator: ceramic separator, energy density of 200Wh / kg), and the injected battery cell was vacuum sealed in a pre-sealing machine with a dew point temperature ≤-50℃, a vacuum degree ≤-95kPa and 180℃. Then, it was placed in an oven at 45℃ and left to stand for 12h to allow the pre-solidified liquid to fully and efficiently wet the battery cell. The uniformly impregnated cell was heated in an oven at 60°C for 24 hours. The large number of free radicals generated by the thermal decomposition of the initiator initiated the polymerization of monomers in the pre-solidified liquid, thereby solidifying all the pre-solidified liquids that were fully impregnated inside the cell. This resulted in the preparation of a high-efficiency, well-impregnated, uniformly cured, and highly safe in-situ solid-state battery.

[0030] The internal resistance and charge-discharge performance of the prepared in-situ solid-state battery were tested, and the results are shown in Table 2 and 3. Figure 1 , Figure 3 .

[0031] Example 4: A method for preparing an in-situ solid-state battery includes the following steps: The pre-solidified liquid prepared in Example 2 was injected into a pre-prepared 1Ah soft-pack battery cell, and the injected battery cell was vacuum sealed in a pre-sealing machine with a dew point temperature ≤-50℃, a vacuum degree ≤-95kPa, and a temperature of 180℃. Then, it was placed in an oven at 35℃ and left to stand for 24 hours to allow the pre-solidified liquid to fully and efficiently wet the battery cell. The uniformly impregnated cell was heated in an oven at 65°C for 12 hours. The large number of free radicals generated by the thermal decomposition of the initiator initiated the polymerization of monomers in the pre-solidified liquid, thereby solidifying all the pre-solidified liquids that were fully impregnated inside the cell. This resulted in the preparation of a high-efficiency, well-impregnated, uniformly cured, and highly safe in-situ solid-state battery.

[0032] The internal resistance and charge-discharge performance of the prepared in-situ solid-state battery were tested, and the results are shown in Table 2 and 3. Figure 1 , Figure 3 .

[0033] Comparative Example 1: A method for preparing a pre-solidified liquid includes the following steps: In a glove box, LiPF6 was dissolved in a mixed solution of ethylene carbonate and methyl ethyl carbonate (mass ratio of ethylene carbonate to methyl ethyl carbonate 3:7) to prepare a 1.2 mol / L LiPF6 electrolyte. According to the mass percentage, weigh 85% of LiPF6 electrolyte, 12% of methyl methacrylate monomer, and 3% of pentaerythritol triacrylate monomer, mix them evenly, and then add 2% of azobisisovalerate initiator according to the total mass of methyl methacrylate monomer and pentaerythritol triacrylate monomer. After stirring evenly, prepare a pre-solidified liquid. 2 ml of the pre-solidified liquid was placed into a 10 ml glass bottle and sealed in an argon-filled glove box to ensure the bottle was free of O2 and moisture. After standing at 35°C for 24 hours, 40% of the pre-solidified liquid had solidified, indicating that the current immersion temperature for in-situ solid-state batteries can only be room temperature or lower. After standing at 60°C for another 24 hours, all the pre-solidified liquid completely solidified. The solidified electrolyte did not exhibit flame-retardant properties.

[0034] Comparative Example 2: A method for preparing a pre-solidified liquid includes the following steps: In a glove box, LiPF6 was dissolved in a solution composed of ethylene carbonate and methyl ethyl carbonate (mass ratio of ethylene carbonate to methyl ethyl carbonate 3:7) to prepare a 1.2 mol / L LiPF6 electrolyte. According to the mass percentage, weigh 84% of LiPF6 electrolyte, 12% of methyl methacrylate monomer, 3% of pentaerythritol triacrylate monomer and 1% of ethoxy(pentafluoro)cyclotriphosphazene, mix them evenly, and then add 1% of azobisisovalerate initiator according to the mass of trimethylolpropane trimethacrylate monomer. After stirring evenly, prepare a pre-solidified liquid. Take 2 ml of the above pre-solidified liquid and put it into a 10 ml glass bottle. Seal the bottle in an argon atmosphere glove box. After standing the sealed glass bottle at 35°C for 12 hours, the pre-solidified liquid in the glass bottle did not solidify. After standing at 35°C for another 24 hours, about 25% of the pre-solidified liquid in the glass bottle solidified. After standing at 60°C for another 24 hours, 100% of the pre-solidified liquid in the glass bottle solidified.

[0035] The above results indicate that 1% ethoxy(pentafluoro)cyclotriphosphazene additive failed to completely prevent the pre-cured liquid from polymerizing and solidifying after standing at 35℃ for 24 hours. Ignition experiments on the cured electrolyte showed poor flame retardant performance.

[0036] Comparative Example 3: A method for preparing a pre-solidified liquid includes the following steps: In a glove box, LiPF6 was dissolved in a solution composed of ethylene carbonate and methyl ethyl carbonate (mass ratio of ethylene carbonate to methyl ethyl carbonate 3:7) to prepare a 1.2 mol / L LiPF6 electrolyte. Weigh out 76% of the electrolyte, 12% of the methyl methacrylate monomer, 3% of the pentaerythritol triacrylate monomer and 9% of the ethoxy (pentafluoro)cyclotriphosphazene according to the mass percentage, mix them evenly, and then add 2% of the azobisisovalerate initiator according to the total mass of the methoxy polyethylene glycol acrylate monomer and trimethylolpropane trimethacrylate monomer. Stir evenly to prepare a pre-solidified liquid. 2 ml of the above pre-cured solution was placed into a 10 ml glass bottle and sealed in an argon-atmospheric glove box. After standing at 45°C for 12 hours, the pre-cured solution in the glass bottle did not solidify. After standing at 45°C for another 24 hours, no significant solidification occurred. When the temperature was further increased to 65°C and stood for 12 hours, approximately 50% of the pre-cured solution in the glass bottle solidified. After standing at 65°C for another 24 hours, the pre-cured solution in the glass bottle failed to solidify completely, and some residual electrolyte remained. These results indicate that the 9% ethoxy(pentafluoro)cyclotriphosphazene additive effectively prevents the pre-cured solution from polymerizing and solidifying at 45°C for 24 hours, but when the temperature is increased to 65°C for 24 hours, the pre-cured solution cannot be completely solidified. This suggests that the pre-cured solution with 9% ethoxy(pentafluoro)cyclotriphosphazene additive is not suitable for the preparation of in-situ cured batteries.

[0037] Comparative Example 4: A method for preparing an in-situ solid-state battery includes the following steps: The pre-solidified liquid prepared in Comparative Example 1 was injected into a pre-prepared 1Ah soft-pack battery cell, and sealed with a vacuum sealing machine to remove all moisture and O2 from the inside of the cell. Then, it was placed in an oven at 25°C and left to stand for 48 hours to allow the pre-solidified liquid to wet the cell. The wetted cell was then heated in an oven at 60°C for 24 hours to allow the free radicals generated by the thermal decomposition of the initiator to initiate the polymerization of monomers in the pre-solidified liquid, thereby solidifying the pre-solidified liquid inside the cell, thus preparing an in-situ solid-state battery.

[0038] The internal resistance and charge-discharge performance of the prepared in-situ solid-state battery were tested, and the results are shown in Table 1 and 2. Figure 2 .

[0039] Comparative Example 5: A method for preparing an in-situ solid-state battery includes the following steps: The pre-solidified liquid prepared in Comparative Example 1 was injected into the pre-prepared 1Ah soft-pack battery cell, and sealed with a vacuum sealing machine to remove all the moisture and O2 inside the battery cell. Then, it was placed in an oven at 45℃ and left to stand for 12 hours to allow the pre-solidified liquid to wet the battery cell. The above-mentioned impregnated cell is heated in an oven at 60°C for 24 hours, so that the free radicals generated by the thermal decomposition of the initiator initiate the polymerization of monomers in the pre-solid liquid, thereby solidifying the pre-solid liquid inside the cell, thus preparing an in-situ solid-state battery.

[0040] The internal resistance and charge-discharge performance of the prepared in-situ solid-state battery were tested, and the results are shown in Table 1 and 2. Figure 2 .

[0041] Comparative Example 6: A method for preparing an in-situ solid-state battery includes the following steps: In a glove box, LiPF6 was dissolved in a solution composed of ethylene carbonate and methyl ethyl carbonate to prepare a 1.2 mol / L LiPF6 electrolyte. Weigh out 85% of LiPF6 electrolyte, 12% of methoxy polyethylene glycol acrylate, and 3% of trimethylolpropane trimethacrylate monomer according to the mass percentage, mix them evenly, and then add 0.5% of azobisisobutyronitrile initiator, which accounts for the total mass of methoxy polyethylene glycol acrylate monomer and trimethylolpropane trimethacrylate monomer. Stir evenly to prepare a pre-solidified liquid. The prepared pre-solidified liquid was injected into the pre-prepared 1Ah soft-pack battery cell, and sealed with a vacuum sealing machine to remove all the moisture and O2 inside the battery cell. Then, it was placed in an oven at 45°C and left to stand for 12 hours to allow the pre-solidified liquid to wet the battery cell. The above-mentioned impregnated cell is heated in an oven at 65°C for 12 hours, so that the free radicals generated by the thermal decomposition of the initiator initiate the polymerization of monomers in the pre-solid liquid, thereby solidifying the pre-solid liquid inside the cell, thus preparing an in-situ solid-state battery.

[0042] The internal resistance and charge-discharge performance of the prepared in-situ solid-state battery were tested, and the results are shown in Table 1 and 2. Figure 3 .

[0043] Table 1 Comparison of the effects of organophosphorus and fluorine compound addition on pre-solidification liquid wetting and curing Table 2 Performance test data of each in-situ solid-state battery The following conclusions can be drawn from the above test results: First, as shown in Table 1, when the amount of organophosphorus fluorine compound added is in the range of 3% to 7%, the pre-solidified liquid can remain stable at 35 to 45°C for 24 hours without curing, and after standing for 12 to 24 hours at 60 to 65°C, it can be completely cured, and after curing, it has a good flame retardant effect. This indicates that a certain amount of organophosphorus fluorine compound has a polymerization inhibitory and flame retardant effect at higher temperatures, but at even higher temperatures, the amount added is limited and cannot prevent the pre-solidified liquid from completely curing. When the amount added is less than 3%, the pre-solidified liquid begins to cure rapidly at 35 to 45°C. When the amount added is higher than 7%, even after standing for 12 to 24 hours at 60 to 65°C, the pre-solidified liquid fails to completely cure. Therefore, only when the amount of organophosphorus fluorine compound added is in the range of 3% to 7% can the pre-solidified liquid efficiently wet the battery cell at higher temperatures without curing, and the well-wetted pre-solidified liquid can be completely cured at even higher temperatures; Second, from Figure 1 , Figure 2 As can be further seen from Table 2, when the battery with 3% added organophosphorus fluoride compound was first impregnated at 45℃ and then cured at 60℃, the charge-discharge curve and electrical performance of the battery were fully realized. The rate performance was superior to that of Comparative Example 4 (impregnated at 25℃ without added organophosphorus fluoride compound) and Comparative Example 5 (impregnated at 45℃). This is because the impregnation efficiency at room temperature is poor, and the pre-curing solution without added organophosphorus fluoride compound was cured before proper impregnation at high temperature. Both of these results led to poor electrical performance of the cell. Finally, from... Figure 3 The results in Table 2 further confirm the above findings.

[0044] In summary, this invention achieves three beneficial effects simultaneously by adding a small amount of organophosphorus fluorine compound as an additive to the pre-solidified liquid: I. It greatly improves the wetting efficiency of the pre-solid solution during in-situ solid-state battery fabrication; Second, it enables the solidified electrolyte to have a flame-retardant effect, giving the in-situ solid-state battery higher safety performance. Third, it significantly extends the shelf life of the pre-solidified liquid at room temperature, reducing storage and transportation costs. Furthermore, the optimal addition amount of organophosphorus fluorine compounds was optimized to 3%~7% through examples.

[0045] The above embodiments are only for illustrating the technical concept and features of the present invention and should not be construed as limiting the scope of protection of the present invention. Any improvements to the present invention, equivalent substitutions of the materials used in the present invention, additions of auxiliary materials, selection of specific methods, etc., should be covered within the scope of protection of the present invention.

[0046] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0047] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing an in-situ solid-state battery, characterized in that, include: Organophosphorus fluorine compounds were added as polymerization inhibitors to the presolid solution, the presolid solution was injected into the cell, the cell was fully wetted by the presolid solution under temperature A, and the cell with uniform presolid solution was cured at temperature B to prepare an in-situ solid-state battery. Temperature B is higher than temperature A.

2. The method for preparing an in-situ solid-state battery as described in claim 1, characterized in that, The organophosphorus and fluorine compounds include any one or more of ethoxy(pentafluoro)cyclotriphosphazene, pentafluoro(phenoxy)cyclotriphosphazene, and hexa(2,2,2-trifluoroethoxy)cyclotriphosphazene; The organophosphorus fluorine compound accounts for 3% to 7% of the mass of the pre-solidified liquid.

3. The method for preparing an in-situ solid-state battery as described in claim 1, characterized in that, The temperature of A is 35~45℃, and the immersion time of the battery cell is 12~24h; The temperature of B is 60~65℃, and the curing time is 12~24h.

4. The method for preparing an in-situ solid-state battery as described in claim 1, characterized in that, The pre-solidified liquid also includes carbonate-based electrolyte, small molecule monomers, and initiators.

5. The method for preparing an in-situ solid-state battery as described in claim 4, characterized in that, The carbonate-based electrolyte comprises: lithium salt and carbonate solvent; The concentration of lithium salt in the carbonate-based electrolyte is 1~1.5 mol / L; The carbonate-based electrolyte accounts for 78% to 92% of the mass of the prepared presolid solution; The lithium salt includes any one or more of lithium hexafluorophosphate, lithium bis(difluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(oxalateborate), and lithium difluorooxalateborate. The carbonate solvent is a mixed solution of ethylene carbonate and methyl ethyl carbonate, with a mass ratio of ethylene carbonate to methyl ethyl carbonate of 3:

7.

6. The method for preparing an in-situ solid-state battery as described in claim 4, characterized in that, The small molecule monomer is a small molecule monomer having one or more carbon-carbon double bonds; The mass ratio of the small molecule monomer in the pre-solidified liquid is 5%~15%; The small molecule monomers specifically include any one or more of the following: methyl methacrylate, methoxy polyethylene glycol acrylate, methyl acrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate.

7. The method for preparing an in-situ solid-state battery as described in claim 4, characterized in that, The initiator is an initiator with a half-life of 10 hours and a decomposition temperature greater than or equal to 60°C. The initiator accounts for 0.5% to 2% of the mass of the small molecule monomer; The initiator includes any one or more of azobisisobutyronitrile, azobisisovalerate, dimethyl azobisisobutyrate, and lauroyl peroxide.

8. The method for preparing an in-situ solid-state battery as described in claim 4, characterized in that, The method for preparing the pre-solidified liquid includes: In an argon-filled glove box, lithium salts are added to carbonate solvents and stirred until homogeneous to prepare a carbonate-based electrolyte. Small molecule monomers, initiators, organophosphorus and fluorine compounds, and carbonate-based electrolytes are stirred in proportion to prepare a pre-solidified solution.

9. The method for preparing an in-situ solid-state battery as described in claim 1, characterized in that, After injecting the pre-solidifying liquid into the battery cell, the specific methods for wetting the battery cell include: Vacuum sealing of the liquid-filled battery cells is performed using a pre-sealing machine with a dew point temperature ≤-50℃, a vacuum degree ≤-95kPa and a temperature of 180℃. The cells are then placed in an oven at 35~45℃ and left to stand for 12~24 hours to allow the pre-solidified liquid to fully wet the battery cells. The battery cell includes an NCM911 positive electrode, a silicon-carbon 450 negative electrode, and a ceramic separator stack, and the designed capacity of the battery cell is 1Ah.

10. An in-situ solid-state battery, characterized in that, The in-situ solid-state battery is prepared by the preparation method of the in-situ solid-state battery according to any one of claims 1-9.

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