A thermally responsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, a preparation method thereof and a lithium metal battery

Abstract

This invention proposes a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The thermoresponsive polymer solid electrolyte comprises a Lewis lithium salt initiator, a cationic polymerization inhibitor, and a solvent. The Lewis lithium salt initiator includes a lithium salt capable of reacting with trace amounts of water to form a protic acid, the cationic polymerization inhibitor includes a lithium salt capable of coordinating with the Lewis lithium salt initiator, and the solvent includes a cationic polymerization solvent. The lithium metal battery containing this electrolyte system maintains a high ionic conductivity liquid state during room temperature cycling, significantly suppresses severe side reactions between lithium metal and the electrolyte under thermal abuse conditions, reduces the interfacial heat generation rate and the risk of electrolyte volatilization, and improves the thermal stability of the electrolyte.

Description

Technical Field

[0001] This invention relates to the field of electrolyte technology, and in particular to a thermally responsive polymer solid electrolyte based on the synergistic regulation of initiator and inhibitor, its preparation method, and a lithium metal battery. Background Technology

[0002] With the rapid development of electronic devices, electric vehicles, and energy storage systems, higher demands are being placed on the energy density and safety performance of lithium batteries. Lithium metal anodes, due to their ultra-high theoretical specific capacity (3860 mAh / g) and lowest electrochemical reduction potential (3.04 V vs. standard hydrogen potential), are considered ideal anode materials for next-generation high-energy-density rechargeable batteries. However, the high chemical reactivity of lithium metal poses serious interfacial instability and safety risks in practical applications, especially under high-temperature or thermal abuse conditions, where batteries are highly susceptible to performance degradation and even thermal runaway.

[0003] Currently, liquid electrolytes are still the primary electrolytes used in lithium metal batteries, with common solvents including carbonates and ethers. Among these, cyclic ether electrolytes have attracted widespread attention due to their good compatibility with lithium metal. However, under high-temperature or thermal abuse conditions, liquid cyclic ether electrolytes still suffer from problems such as volatility, susceptibility to side reactions, and insufficient thermal stability. On the one hand, solvent evaporation and decomposition at high temperatures generate flammable gases, increasing the risk of battery combustion and explosion. On the other hand, the intensified side reactions between the electrolyte and lithium metal can lead to the destruction of the solid electrolyte interphase (SEI) structure, exposing fresh lithium metal surfaces and further inducing exothermic reactions, resulting in continuous heat accumulation.

[0004] To address the safety concerns of liquid electrolytes under high-temperature conditions, researchers have proposed several improvement strategies: Solvent activity can be reduced by increasing the electrolyte concentration or constructing locally high-concentration electrolytes. High-concentration or locally high-concentration electrolytes can reduce the free solvent content to some extent, thereby slowing down solvent evaporation and improving interfacial stability. However, such systems typically have high viscosity, limited ion transport, and are still difficult to effectively suppress lithium dendrite growth under high-temperature conditions, posing potential safety hazards.

[0005] Safety can be improved by introducing polymer solid or quasi-solid-state electrolytes with high thermal stability. Polymer electrolytes can restrict electrolyte flow, reduce leakage and volatilization, and inhibit lithium dendrite growth to some extent. However, most polymer electrolytes have low ionic conductivity and high interfacial contact resistance at room temperature, often requiring higher temperatures to meet the needs of normal battery operation, making it difficult to balance room temperature electrochemical performance with high-temperature safety.

[0006] By constructing a stable SEI or introducing functional additives to suppress interfacial side reactions, this type of method can improve coulombic efficiency and cycle life to some extent at room temperature. However, under high temperature or thermal abuse conditions, the SEI layer will inevitably undergo thermal decomposition, and the interfacial side reactions will be aggravated again, making it difficult to fundamentally block the continuous generation of heat.

[0007] Gel electrolytes or semi-solid electrolytes can balance conductivity and safety. Gel electrolytes combine the high ionic conductivity of liquid electrolytes with the morphological stability of polymer matrices, but they still rely on solvent transport. Under high-temperature conditions, the solvent in the gel system may still evaporate and migrate, leading to changes in electrolyte composition and performance degradation, with limited improvement in safety.

[0008] Therefore, there is an urgent need to design a thermally responsive electrolyte system that is stable and controlled at room temperature and can undergo rapid structural transformation at high temperature, so as to achieve high-performance operation of lithium metal batteries under normal operating conditions and improve intrinsic safety under thermal abuse conditions. Summary of the Invention

[0009] In view of this, this invention proposes a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The raw materials for the thermoresponsive polymer solid electrolyte include a Lewis lithium salt initiator, a cationic polymerization inhibitor, and a cationic polymerization solvent. At room temperature, the coordination interaction between the cationic polymerization inhibitor and the Lewis lithium salt initiator dominates, keeping the electrolyte in a liquid state for a long time. When the ambient temperature rises, the coordination balance between the initiator and the inhibitor is disrupted, initiating rapid polymerization in the cationic polymerization solvent. The lithium metal battery containing this electrolyte system maintains a liquid state with high ionic conductivity during room temperature cycling, significantly suppresses violent side reactions between lithium metal and the electrolyte under thermal abuse conditions, reduces the interfacial heat generation rate and the risk of electrolyte volatilization, and improves the thermal stability of the electrolyte.

[0010] The technical solution of this invention is implemented as follows: In a first aspect, the present invention provides a thermoresponsive polymer solid electrolyte based on the synergistic regulation of an initiator and an inhibitor, the raw materials of which include a Lewis lithium salt initiator and a cationic polymerization inhibitor solvent. The Lewis lithium salt initiator includes lithium salts capable of reacting with trace amounts of water to form protic acids. The cationic polymerization inhibitor includes a lithium salt capable of coordinating with the Lewis lithium initiator. The solvent includes cationic polymerization solvents.

[0011] This invention provides a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. By rationally screening Lewis lithium salt initiators, cationic polymerization inhibitors, cationic polymerization solvents, and antioxidant solvents, and optimizing the ratio of each component, a thermoresponsive electrolyte system exhibiting differentiated reaction behavior under different temperature conditions is constructed. At room temperature, the cationic polymerization inhibitor coordinates with the Lewis lithium salt initiator, effectively inhibiting the initiator's activity, keeping the electrolyte system in a liquid state with high ionic conductivity. Simultaneously, the Lewis lithium salt initiator preferentially participates in interfacial reactions, promoting the formation of a stable solid electrolyte interface and suppressing parasitic reactions between lithium metal and the electrolyte, thereby improving the battery's room temperature cycle stability. Under high temperature or thermal abuse conditions, the coordination between the inhibitor and the initiator weakens, the initiator activity is released, and rapid cationic polymerization occurs in the cationic polymerization solvent, transforming the electrolyte from a liquid state into a polymer electrolyte with high thermal stability, thereby reducing electrolyte volatility and minimizing interfacial side reactions. Furthermore, the antioxidant solvent further expands the electrolyte's electrochemical stability window, thus broadening the system's application scenarios.

[0012] Based on the above technical solutions, the cationic polymerization inhibitor further includes a lithium salt that can coordinate with the Lewis lithium salt initiator at room temperature and inhibit its initiation ability.

[0013] Based on the above technical solutions, the Lewis lithium salt initiator further includes one or more of lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium hexafluoroantimonyate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorodioxarate phosphate, lithium tetrafluoroborate, and lithium bis(oxarate)borate.

[0014] Based on the above technical solutions, the cationic polymerization inhibitor further includes one or more of lithium nitrate, lithium perchlorate, lithium sulfate, and lithium acetate.

[0015] Based on the above technical solution, the molar ratio of the Lewis lithium salt initiator to the cationic polymerization inhibitor is (1~30):1.

[0016] Insufficient Lewis lithium salt initiator concentration at high temperatures leads to inadequate initiator concentration, hindering rapid conversion and causing severe electrolyte volatilization and loss of electrochemical performance. Conversely, excessive Lewis lithium salt initiator concentration results in the presence of uninhibited free initiators at room temperature, preventing the initiator from maintaining a liquid state and weakening ion conduction at room temperature, thus affecting room temperature electrochemical performance.

[0017] Based on the above technical solution, the concentration of the Lewis lithium salt initiator in the thermally responsive polymer solid electrolyte is further 0.5 mol / L to 6 mol / L.

[0018] Based on the above technical solutions, the cationic polymerization solvent further includes one or more of the following: cyclic ether compounds, ether compounds containing double bonds, and epoxy-functionalized organosilicon compounds.

[0019] Based on the above technical solutions, the solvent further includes an antioxidant solvent, which includes one or more of carbonate compounds, chain ether compounds, and nitrile compounds.

[0020] Based on the above technical solution, the volume ratio of the cationic polymerization solvent to the antioxidant solvent is further (1~99):1.

[0021] Based on the above technical solutions, the cyclic ether compounds further include one or more of tetrahydrofuran, 1,3-dioxapentane, 1,4-dioxane, and 2-methyltetrahydrofuran. The ether compounds containing double bonds include one or more of vinyl ethyl ether, isobutylvinyl ether, divinyl ether, vinyl n-butyl ether, diethylene glycol divinyl ether, ethylene glycol monovinyl ether, triethylene glycol divinyl ether, and tetraethylene glycol divinyl ether. The epoxy-functionalized organosilicon compounds include one or more of 1,3-bis(3-glycidyl etheroxypropyl)tetramethyldisiloxane and 3-(2,3-epoxypropoxy)propyltrimethoxysilane. The carbonate compounds include one or more of fluoroethylene carbonate, difluoroethylene carbonate, methyl ethyl carbonate, and dimethyl carbonate. The chain-like ether compounds include one or more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether. The nitrile compounds include one or more of adiponitrile, fluoroadiponitrile, fluoroacetonitrile, and difluoroacetonitrile.

[0022] Secondly, the present invention also provides a method for preparing the thermally responsive polymer solid electrolyte, comprising the following steps: mixing a Lewis lithium salt initiator, a cationic polymerization inhibitor, and a solvent to obtain the electrolyte.

[0023] Thirdly, the present invention also provides a lithium metal battery comprising the thermally responsive polymer solid electrolyte.

[0024] Based on the above technical solutions, the positive electrode active material of the lithium metal battery further includes one or more of layered oxides and polyanionic compounds.

[0025] Based on the above technical solutions, the layered oxide structure further includes one or more of lithium cobalt oxide and lithium nickel cobalt manganese oxide, and the polyanionic compound includes lithium iron phosphate.

[0026] Based on the above technical solutions, the method for preparing the lithium metal battery further includes: mixing the solvent, adding a Lewis lithium salt initiator and a cationic polymerization inhibitor, dissolving them completely to obtain an electrolyte, injecting the electrolyte between the positive and negative electrodes inside the battery so that the electrolyte fully wets the positive and negative electrodes and the separator, and then completing the battery encapsulation; or, dripping the electrolyte onto the positive electrode, the separator and the negative electrode, and then completing the battery assembly.

[0027] Compared to existing technologies, this invention offers the following advantages: It provides a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. In the thermoresponsive polymer solid electrolyte, at room temperature, the coordination interaction between the cationic polymerization inhibitor and the Lewis lithium salt initiator dominates, maintaining the electrolyte in a liquid state for an extended period. When the ambient temperature rises, the coordination balance between the initiator and inhibitor is disrupted, initiating rapid polymerization of the cationic polymerization solvent. The lithium metal battery maintains a liquid state with high ionic conductivity during room temperature cycling, significantly suppressing severe side reactions between lithium metal and the electrolyte under thermal abuse conditions, reducing the interfacial heat generation rate and the risk of electrolyte volatilization, and improving the thermal stability of the electrolyte. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 Optical photographs of three different Lewis lithium salt initiators prepared for the performance testing of this invention, namely lithium bis(fluorosulfonyl)imide (LiFSI), lithium hexafluorophosphate (LiPF6), and lithium difluorooxalate borate (LiDFOB), after being stirred in DOL for 5 minutes and 12 hours respectively. Figure 2 An optical photograph of lithium nitrate (LiNO3), a cationic polymerization inhibitor prepared in Comparative Example 1 of this invention, after stirring in DOL for 5 minutes; Figure 3The conversion rate of the thermoresponsive electrolyte based on initiator-inhibitor synergistic regulation prepared in Example 1 of this invention was obtained by nuclear magnetic resonance hydrogen spectrum after standing at 30℃ and 80℃ for 2h. Figure 4 LSV testing was performed on the Li||SS battery containing an initiator-inhibitor synergistically regulated thermally responsive electrolyte in Example 1 of this invention; Figure 5 Optical images of the thermoresponsive electrolyte based on initiator-inhibitor synergistic regulation prepared in Example 2 of the present invention after standing at (a) 30 ℃ and (b) 80 ℃ for 2 h; Figure 6 The Raman spectrum of the thermally responsive electrolyte based on initiator-inhibitor synergistic regulation prepared in Example 2 of the present invention as a function of time at 80°C. Figure 7 LSV testing was performed on the Li||SS battery containing an initiator-inhibitor synergistically regulated thermally responsive electrolyte in Example 3 of the present invention; Figure 8 The cycling performance of the Li||LFP battery containing an initiator-inhibitor synergistically regulated thermally responsive electrolyte in Example 3 of this invention at 1 C rate and 30°C; Figure 9 The rate performance of the Li||LFP battery containing an initiator-inhibitor synergistically regulated thermally responsive electrolyte in Example 3 of this invention; Figure 10 The cycling performance of the Li||NCM811 battery containing an initiator-inhibitor synergistically regulated thermally responsive electrolyte in Example 3 of this invention at 1 C rate and 30°C; Figure 11 The cycling performance of the Li||LFP battery containing an initiator-inhibitor synergistically regulated thermally responsive electrolyte in Example 3 of this invention at 1 C rate and 100 °C; Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] In the following specific implementation methods, unless otherwise specified, the reagents and materials used are all conventional reagents and materials that can be obtained commercially.

[0032] Unless otherwise specified, the purity of the cationic polymerization solvent and antioxidant solvent of the present invention is 100%.

[0033] Example 1 This embodiment prepares a thermoresponsive polymer solid electrolyte and a lithium metal battery based on initiator-inhibitor synergistic regulation. The raw materials for the thermoresponsive polymer solid electrolyte include: (1) Cationic polymerization inhibitor: lithium nitrate (LiNO3); (2) Lithium Lewis acid initiator: LiFSI; (3) Cationic polymerization solvent: 1,3-dioxane (DOL); The molar ratio of the Lewis lithium salt initiator to the cationic polymerization inhibitor is 15:1, the concentration of the Lewis lithium salt initiator in the thermally responsive polymer solid electrolyte is 1.5 mol / L, and the concentration of the cationic polymerization inhibitor in the thermally responsive polymer solid electrolyte is 0.1 mol / L.

[0034] The preparation method of the thermoresponsive polymer solid electrolyte includes: adding a cationic polymerization inhibitor and a Lewis lithium salt initiator to 1 mL of cationic polymerization solvent, stirring at 30 °C for about 2 h until completely dissolved, and finally obtaining a uniformly mixed thermoresponsive polymer solid electrolyte.

[0035] The above electrolytes were allowed to stand at 30℃ and 80℃ for 2 hours respectively, and then subjected to proton nuclear magnetic resonance spectroscopy. The results are as follows: Figure 3 As shown, after standing at 30℃ for 2 hours, the conversion rate of DOL was 0%, indicating that LiNO3 significantly inhibits the binding of Lewis lithium anions to trace amounts of water by coordinating with them at room temperature, thereby suppressing DOL conversion. However, after standing at 80℃ for 2 hours, the DOL conversion rate was 13%, indicating that high temperature significantly weakens the conversion of NO3. - The interaction between the lithium Lewis acid anion and the DOL leads to the generation of free lithium Lewis acid anions in the electrolyte, which react with trace amounts of water to generate H protons that attack DOL, thereby initiating the polymerization of the electrolyte.

[0036] The preparation method of lithium metal battery includes: taking 25 μL of the obtained electrolyte, dropping it onto the LiFePO4 (LFP) positive electrode, then covering it with a polypropylene separator, adding another 25 μL of electrolyte to wet the separator, then stacking the negative electrode lithium metal sheet and nickel foam; finally, encapsulating the battery with a casing to obtain a lithium metal battery.

[0037] The LFP positive electrode described above was replaced with a stainless steel gasket, and the test Li||SS cell of this embodiment was assembled as described above, and linear sweep voltammetry (LSV) was performed. The results are as follows: Figure 4 As shown, the electrochemical window of the thermally responsive electrolyte in this embodiment was found to be 3.8 V through testing.

[0038] Electrochemical performance of the lithium metal battery with the above-mentioned cathode (LFP) was characterized. After long-term cycling at 30 °C and a charge-discharge rate of 1 C, the initial discharge specific capacity was 158 mAh / g, and it retained 90% of its room-temperature capacity after 200 cycles. Further electrochemical performance was characterized by rate testing. At an initial rate of 0.2 C, the battery's discharge specific capacity was approximately 177 mAh / g. When the rate was increased to 10 C, the discharge specific capacity was 106 mAh / g. When the rate was restored from 10 C to the initial 0.2 C, the discharge specific capacity quickly recovered to approximately 176 mAh / g.

[0039] Example 2 This embodiment provides a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation and its preparation method. The raw materials for the thermoresponsive polymer solid electrolyte include: (1) Cationic polymerization inhibitor: lithium nitrate (LiNO3); (2) Lithium Lewis acid initiator: LiFSI; (3) Cationic polymerization solvent: 1,3-dioxane and triethylene glycol divinyl ether are mixed at a volume ratio of 4:1; The molar ratio of the Lewis lithium salt initiator to the cationic polymerization inhibitor is 1:1, the concentration of the Lewis lithium salt initiator in the thermally responsive polymer solid electrolyte is 0.5 mol / L, and the concentration of the cationic polymerization inhibitor in the thermally responsive polymer solid electrolyte is 0.5 mol / L.

[0040] The preparation method of the thermoresponsive polymer solid electrolyte includes: adding a cationic polymerization inhibitor and a Lewis lithium salt initiator to 1 mL of cationic polymerization solvent, stirring at 30 °C for about 2 h until completely dissolved, and finally obtaining a uniformly mixed thermoresponsive polymer solid electrolyte.

[0041] After the above electrolytes were left to stand at 30℃ and 80℃ for 2 hours respectively, the physical states of the electrolytes were as follows: Figure 5 As shown, the electrolyte remains a liquid with high ionic conductivity after standing at 30°C for 2 hours, but transforms into a transparent, pale yellow solid electrolyte after standing at 80°C for 2 hours.

[0042] The above electrolyte was subjected to Raman spectroscopy testing at 80℃ for 2 hours, as follows: Figure 6 As shown, at 80℃, over time, 840 cm -1 The peak intensity of the C-O-C stretching vibration of PDOL gradually increases at 940 cm⁻¹. -1The C-O-C stretching vibration peak of the DOL molecule gradually weakens at 1630 cm⁻¹, indicating that a DOL polymerization reaction is occurring in this system at 80 °C. -1 The C=C stretching vibration peak at 80℃ disappeared completely after 30 min, indicating that TEGDVE polymerizes rapidly at this temperature. The introduction of TEGDVE can accelerate the phase transition rate of the electrolyte at high temperature.

[0043] Example 3 This embodiment provides a thermally responsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery.

[0044] The raw materials for the thermally responsive polymer solid electrolyte include: (1) Cationic polymerization inhibitor: lithium nitrate (LiNO3); (2) Lithium Lewis acid initiator: LiFSI; (3) Cationic polymerization solvents: 1,3-dioxane (DOL), triethylene glycol divinyl ether (TEGDVE); (4) Antioxidant solvent: triethylene glycol dimethyl ether; The molar ratio of the Lewis lithium salt initiator to the cationic polymerization inhibitor is 30:1, the concentration of the Lewis lithium salt initiator in the thermally responsive polymer solid electrolyte is 6 mol / L, and the concentration of the cationic polymerization inhibitor in the thermally responsive polymer solid electrolyte is 0.2 mol / L.

[0045] The volume ratio of 1,3-dioxapentane, triethylene glycol divinyl ether, and triethylene glycol dimethyl ether is 28:7:15, and the total volume of the cationic polymerization solvent and the antioxidant solvent is 1 mL.

[0046] The preparation method of the thermoresponsive polymer solid electrolyte includes: stirring the cationic polymerization solvent and the antioxidant solvent at 30°C for 2 hours until completely dissolved, adding the cationic polymerization inhibitor and the Lewis lithium salt initiator and stirring at 30°C for 2 hours until completely dissolved, and finally obtaining a uniformly mixed thermoresponsive polymer solid electrolyte.

[0047] The preparation method of lithium metal battery includes: taking 25 μL of the obtained electrolyte, dropping it onto the LiFePO4 (LFP) positive electrode, then covering it with a polypropylene separator, adding another 25 μL of electrolyte to wet the separator, then stacking the negative electrode lithium metal sheet and nickel foam; finally, encapsulating the battery with a casing to obtain a lithium metal battery.

[0048] The LFP cathode described above was replaced with a stainless steel gasket, and the Li||SS battery for testing in this embodiment was assembled as described above, followed by linear sweep voltammetry (LSV) testing. The electrochemical window of the polymer-based solid electrolyte in this embodiment was obtained through testing, as shown below. Figure 7 As shown, the electrochemical window of the polymer-based solid electrolyte in this embodiment reaches 4.6 V.

[0049] The electrochemical performance of the lithium metal battery with the above-mentioned cathode (LFP) was characterized. For example... Figure 8 As shown, after long-term cycling at 30 °C and a charge-discharge rate of 1 C, the initial discharge specific capacity is 155 mAh / g, and it retains 95% of its room temperature capacity after 200 cycles. Further characterization of the electrochemical performance was achieved through rate testing, such as... Figure 9 As shown, at the initial 0.2 C rate, the battery's discharge specific capacity is approximately 183 mAh / g. When the rate is increased to 10 C, the battery's discharge specific capacity is 128 mAh / g. When the rate recovers from 10 C to the initial 0.2 C, the battery's discharge specific capacity quickly rebounds to approximately 182 mAh / g, without significant irreversible capacity loss, indicating that the system exhibits good structural stability and reversibility after rate shocks.

[0050] Replace the LFP cathode described above with an NCM811 cathode, assemble the test Li||NCM811 battery of this embodiment as described above, and perform a constant current charge-discharge cycle test at 30°C at a 1 C rate. Figure 10 As shown, after two activation cycles at 0.1 C, the discharge specific capacity of Li||NCM is 211 mAh / g. When the rate is increased to 1 C, it achieves an initial discharge specific capacity of 163 mAh / g and an average coulombic efficiency of 99.2%, indicating that the electrolyte has good electrochemical compatibility with the NCM cathode. A stable and low-resistance CEI film can be formed at the cathode interface, effectively suppressing the oxidation decomposition reaction and supporting the normal lithium insertion / extraction process of the cathode in the high potential range. After 135 cycles, the battery retains 80.1% of its capacity, corresponding to a reversible capacity of 130.9 mAh / g, demonstrating good cycle stability.

[0051] The electrochemical performance of the lithium metal battery with the above-mentioned positive electrode LFP was characterized at 100°C. For example... Figure 11As shown, constant current charge-discharge cycle tests were conducted at 100℃ with a charge-discharge rate of 1 C. In the first cycle, with activation at 0.1 C, the system achieved a discharge specific capacity of approximately 176 mAh / g and a coulombic efficiency of approximately 90%, indicating that the system can respond rapidly and undergo effective conversion at high temperatures, quickly constructing a stable polymer electrolyte phase and protective layer structure at the electrode interface. After 195 cycles, it still maintains approximately 95% capacity retention, corresponding to a discharge specific capacity of approximately 170 mAh / g, while the average coulombic efficiency is as high as 99.8%, demonstrating extremely high reaction reversibility and interfacial stability.

[0052] Example 4 This embodiment provides a thermally responsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery.

[0053] The raw materials for the thermally responsive polymer solid electrolyte include: (1) Cationic polymerization inhibitor: lithium nitrate (LiNO3); (2) Lithium Lewis acid initiator: LiFSI; (3) Cationic polymerization solvents: 1,3-dioxopentane (DOL), 1,3-bis(3-glycidyl etheroxypropyl)tetramethyldisiloxane (TMSO); (4) Antioxidant solvent: triethylene glycol dimethyl ether; The mass ratio of the Lewis lithium salt initiator to the cationic polymerization inhibitor is 30:1, the concentration of the Lewis lithium salt initiator in the thermally responsive polymer solid electrolyte is 6 mol / L, and the concentration of the cationic polymerization inhibitor in the thermally responsive polymer solid electrolyte is 0.2 mol / L.

[0054] The volume ratio of 1,3-dioxopentane, 1,3-bis(3-glycidyl etheroxypropyl)tetramethyldisiloxane, and triethylene glycol dimethyl ether is 28:7:15. The total volume of the cationic polymerization solvent and the antioxidant solvent is 1 mL.

[0055] The preparation method of the thermoresponsive polymer solid electrolyte includes: stirring the cationic polymerization solvent and the antioxidant solvent at 30°C for 2 hours until completely dissolved, adding the cationic polymerization inhibitor and the Lewis lithium salt initiator and stirring at 30°C for 2 hours until completely dissolved, and finally obtaining a uniformly mixed thermoresponsive polymer solid electrolyte.

[0056] The preparation method of lithium metal includes: taking 25 μL of the obtained electrolyte, dropping it onto the LiFePO4 (LFP) positive electrode, then covering it with a polypropylene separator, adding another 25 μL of electrolyte to wet the separator, then stacking the negative electrode lithium metal sheet and nickel foam; finally, encapsulating the battery with a casing to obtain a lithium metal battery.

[0057] The LFP cathode described above was replaced with a stainless steel gasket, and the test Li||SS cell of this embodiment was assembled as described above, followed by linear sweep voltammetry (LSV) testing. The electrochemical window of the thermally responsive electrolyte in this embodiment was found to be 4.7 V.

[0058] Electrochemical performance of the lithium metal battery with the above-mentioned cathode (LFP) was characterized. After long-term cycling at 30°C and a charge-discharge rate of 1 C, the initial discharge specific capacity was 153 mAh / g, and it retained 92% of its room-temperature capacity after 200 cycles. Further electrochemical performance was characterized by rate testing. At an initial rate of 0.2 C, the battery's discharge specific capacity was approximately 175 mAh / g. When the rate was increased to 10 C, the discharge specific capacity was 110 mAh / g. When the rate recovered from 10 C to the initial 0.2 C, the discharge specific capacity quickly rebounded to approximately 174 mAh / g without significant irreversible capacity loss, indicating that the system exhibits good structural stability and reversibility after rate shocks.

[0059] The LFP cathode described above was replaced with an NCM811 cathode, and the test Li||NCM811 battery of this embodiment was assembled as described above. A constant current charge-discharge cycle test at 1 C rate was conducted at 30°C. After two activation cycles at 0.1 C, the discharge specific capacity of Li||NCM was 205 mAh / g. When the rate increased to 1 C, it achieved an initial discharge specific capacity of 160 mAh / g and an average coulombic efficiency of 99.1%. After 110 cycles, the capacity retention was 83.2%, corresponding to a reversible capacity of 133.1 mAh / g, demonstrating good cycle stability.

[0060] The electrochemical performance of the lithium metal battery with the above-mentioned positive electrode LFP was characterized at 100°C. For example... Figure 9 As shown, constant current charge-discharge cycle tests were conducted at 100℃ with a charge-discharge rate of 1 C. In the first cycle, with activation at 0.1 C, the system achieved a discharge specific capacity of approximately 174 mAh / g and a coulombic efficiency of approximately 88%, indicating that the system can respond rapidly and undergo effective conversion at high temperatures, quickly constructing a stable polymer electrolyte phase and protective layer structure at the electrode interface. After 170 cycles, it still maintains approximately 96% capacity retention, corresponding to a discharge specific capacity of approximately 168 mAh / g, while the average coulombic efficiency is as high as 99.5%, demonstrating extremely high reaction reversibility and interfacial stability.

[0061] Example 5 This embodiment provides a thermally responsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Embodiment 1 is that lithium hexafluorophosphate is used instead of LiFSI, lithium perchlorate is used instead of lithium nitrate, and 1,4-dioxane is used instead of 1,3-dioxane.

[0062] Example 6 This embodiment provides a thermally responsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Embodiment 1 is that lithium hexafluoroarsenate is used instead of LiFSI, lithium sulfate is used instead of lithium nitrate, and vinyl ethyl ether is used instead of 1,3-dioxane.

[0063] Example 7 This embodiment provides a thermally responsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Embodiment 1 is that lithium hexafluoroantimonyate is used instead of LiFSI, lithium acetate is used instead of lithium nitrate, and 3-(2,3-epoxypropoxy)propyltrimethoxysilane is used instead of 1,3-dioxopentane.

[0064] Example 8 This embodiment provides a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Example 1 is that lithium bis(trifluoromethanesulfonyl)imide is used instead of LiFSI.

[0065] Example 9 This embodiment provides a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Embodiment 1 is that lithium difluorodioxalate phosphate is used instead of LiFSI.

[0066] Example 10 This embodiment provides a thermally responsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Embodiment 1 is that lithium tetrafluoroborate is used instead of LiFSI.

[0067] Example 11 This embodiment provides a thermally responsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Embodiment 1 is that lithium bis(oxalatoborate) is used instead of LiFSI.

[0068] Example 12 This embodiment provides a thermally responsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Embodiment 1 is that, while maintaining the same amount of Lewis lithium salt initiator, a mixture of lithium bis(oxalateborate), lithium hexafluorophosphate, and lithium difluorooxalateborate in a mass ratio of 1:1:1 is used to replace LiFSI.

[0069] Example 13 This embodiment provides a thermally responsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Example 1 is that, while keeping the amount of cationic polymerization inhibitor unchanged, lithium nitrate is replaced with a mixture of lithium nitrate, lithium perchlorate, and lithium sulfate in a mass ratio of 1:1:1.

[0070] Example 14 This embodiment provides a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Example 3 is that triethylene glycol dimethyl ether is replaced with fluoroethylene carbonate.

[0071] Example 15 This embodiment provides a thermally responsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Embodiment 3 is that adiponitrile is used instead of triethylene glycol dimethyl ether.

[0072] Example 16 This embodiment provides a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Example 1 is that vinyl ethyl ether is used instead of 1,3-dioxane.

[0073] Example 17 This embodiment provides a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Example 1 is that isobutylethylene ether is used instead of 1,3-dioxane.

[0074] Example 18 This embodiment provides a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Example 1 is that divinyl ether is used instead of 1,3-dioxane.

[0075] Example 19 This embodiment provides a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Example 1 is that vinyl n-butyl ether is used instead of 1,3-dioxane.

[0076] Example 20 This embodiment provides a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Example 1 is that diethylene glycol divinyl ether is used instead of 1,3-dioxane.

[0077] Example 21 This embodiment provides a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Example 1 is that ethylene glycol monovinyl ether is used instead of 1,3-dioxane.

[0078] Example 22 This embodiment provides a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. The difference between this embodiment and Example 1 is that tetraethylene glycol divinyl ether is used instead of 1,3-dioxane.

[0079] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not contain a Lewis lithium salt initiator.

[0080] When preparing electrolytes, such as Figure 2 As shown, the cationic polymerization inhibitor lithium nitrate remained undissolved, appearing as fine white particles suspended at the bottom of the bottle. This indicates that the cationic polymerization solvent DOL cannot dissociate the cationic polymerization inhibitor lithium nitrate, and the electrolyte remains liquid. Simply adding the inhibitor lithium nitrate to the cationic polymerization solvent DOL did not result in dissolution, indicating that DOL cannot dissociate lithium nitrate. However, when both the cationic polymerization inhibitor lithium nitrate and the cationic polymerization initiator LiFSI were added simultaneously, the solution became clear and transparent. This demonstrates that lithium nitrate achieves its own dissolution and inhibits the LiFSI-initiated DOL polymerization effect through coordination with LiFSI.

[0081] Comparative Example 2 The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not contain cationic polymerization inhibitors.

[0082] Performance testing 1. Add the Lewis lithium salt initiators lithium bis(fluorosulfonyl)imide (LiFSI), lithium hexafluorophosphate (LiPF6), and lithium difluorooxalate borate (LiDFOB) to DOL respectively, so that the final concentration of the Lewis lithium salt initiator is 1 mol / L. Stir for 5 min. Figure 1 As shown, the rapid polymerization rates of DOL initiated by LiFSI and LiPF6 caused the DOL to rapidly polymerize upon addition of lithium salts, encapsulating other lithium salts and hindering their dissolution. The encapsulated lithium salts deposited at the bottom of the bottle and could not be dissolved by stirring. However, when LiDFOB was added to DOL and immediately stirred, no incomplete dissolution of lithium salts was observed, indicating that the polymerization rate initiated by LiDFOB was significantly slower than that of LiFSI and LiPF6. After 12 hours, the DOL groups containing LiPF6 and LiDFOB were completely solidified, but the DOL in the LiFSI group remained a flowable, relatively viscous liquid, indicating that even when lithium salts could not be completely dissolved, the polymerization rate initiated by LiPF6 was still faster than that of LiFSI. In conclusion, the order of DOL solidification rates initiated by lithium Lewis acid initiators at the same concentration is: LiPF6 > LiFSI > LiDFOB.

[0083] 2. The physical states of the electrolytes prepared in Comparative Examples 1 and 2 were observed. It was found that lithium nitrate, a cationic polymerization inhibitor, could not be dissolved when only the cationic polymerization inhibitor was added, indicating that the cationic polymerization solvent DOL could not dissociate lithium nitrate. When only the Lewis lithium salt initiator was added, DOL polymerized rapidly. This is because the Lewis lithium salt initiator can combine with trace amounts of water to form a protic acid, thereby initiating the ring-opening polymerization of DOL. However, when both the cationic polymerization inhibitor lithium nitrate and the Lewis lithium salt initiator were added simultaneously, the electrolyte became clear and transparent. This indicates that the addition of the Lewis lithium salt initiator dissolved lithium nitrate, while the electrolyte remained liquid at room temperature for a long time. This suggests that the cationic polymerization inhibitor lithium nitrate and the Lewis lithium salt initiator coordinated, limiting their initiation performance.

[0084] In summary, this invention provides a thermoresponsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, its preparation method, and a lithium metal battery. In the thermoresponsive polymer solid electrolyte, at room temperature, the coordination interaction between the cationic polymerization inhibitor and the Lewis lithium salt initiator dominates, maintaining the electrolyte in a liquid state for a long period. When the ambient temperature rises, the coordination balance between the initiator and inhibitor is disrupted, initiating rapid polymerization of the cationic polymerization solvent. The lithium metal battery maintains a liquid state with high ionic conductivity during room temperature cycling, significantly suppresses violent side reactions between lithium metal and the electrolyte under thermal abuse conditions, reduces the interfacial heat generation rate and the risk of electrolyte volatilization, and improves the thermal stability of the electrolyte.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermally responsive polymer solid electrolyte based on initiator-inhibitor synergistic regulation, characterized in that, Its raw materials include lithium Lewis acid initiators, cationic polymerization inhibitors, and solvents. The Lewis lithium salt initiator includes lithium salts capable of reacting with trace amounts of water to form protic acids. The cationic polymerization inhibitor includes a lithium salt capable of coordinating with the Lewis lithium initiator. The solvent includes cationic polymerization solvents.

2. The heat-responsive polymer solid electrolyte according to claim 1, wherein The Lewis lithium salt initiator includes one or more of lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium hexafluoroantimonyate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorodioxarate phosphate, lithium tetrafluoroborate, and lithium bis(oxarate)borate.

3. The heat-responsive polymer solid electrolyte according to claim 1, wherein The cationic polymerization inhibitor includes one or more of lithium nitrate, lithium perchlorate, lithium sulfate, and lithium acetate.

4. The heat-responsive polymer solid electrolyte according to claim 2 or 3, wherein The molar ratio of the Lewis lithium salt initiator to the cationic polymerization inhibitor is (1~30):

1.

5. The thermally responsive polymer solid electrolyte as described in claim 2, characterized in that, The concentration of the Lewis lithium salt initiator in the thermally responsive polymer solid electrolyte is 0.5 mol / L to 6 mol / L.

6. The thermally responsive polymer solid electrolyte as described in claim 1, characterized in that, The cationic polymerization solvent includes one or more of the following: cyclic ether compounds, ether compounds containing double bonds, alkenyl compounds containing double bonds, and epoxy-functionalized organosilicon compounds.

7. The thermally responsive polymer solid electrolyte as described in claim 6, characterized in that, The cyclic ether compounds include one or more of tetrahydrofuran, 1,3-dioxapentane, 1,4-dioxane, and 2-methyltetrahydrofuran. The ether compounds containing double bonds include one or more of vinyl ethyl ether, isobutylvinyl ether, divinyl ether, vinyl n-butyl ether, diethylene glycol divinyl ether, ethylene glycol monovinyl ether, triethylene glycol divinyl ether, and tetraethylene glycol divinyl ether. The epoxy-functionalized organosilicon compounds include one or more of 1,3-bis(3-glycidyl etheroxypropyl)tetramethyldisiloxane and 3-(2,3-epoxypropoxy)propyltrimethoxysilane.

8. The thermally responsive polymer solid electrolyte as described in claim 1, characterized in that, The solvent also includes one or more of carbonate compounds, chain ether compounds, and nitrile compounds.

9. The method for preparing the thermally responsive polymer solid electrolyte according to any one of claims 1 to 8, characterized in that, The process includes the following steps: mixing a Lewis lithium salt initiator, a cationic polymerization inhibitor, and a solvent.

10. A lithium metal battery, characterized in that, Including the thermally responsive polymer solid electrolyte as described in any one of claims 1 to 8.

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