A preparation method and application of a solid-state polymer electrolyte based on dynamic dipole compensation

Abstract

The application provides a preparation method and application of a solid-state polymer electrolyte based on dynamic dipole compensation, and belongs to the technical field of solid-state polymer electrolytes.The solid-state polymer electrolyte is prepared by using polyurethane epoxy resin and PEO as polymers, compounding at the molecular scale to form a mechanical interlocking structure, and then doping and modifying the mechanical interlocking structure by MOF-177 material to obtain a new composite solid-state polymer electrolyte with "charge balance / dynamic dipole compensation". Through the synergistic effect of the mechanical interlocking composite structure and the MOF, a more uniform electric potential and a nearly "charge neutral" interface environment (referring to the minimization of interface potential fluctuation / electrostatic non-uniformity, rather than no potential difference) are constructed, so that the Li + migration energy barrier is reduced, ion migration and diffusion are improved, the uniform interface electric field and Li + flux are obtained, the "hot spot" deposition is weakened, the interface contact stability and the anti-branching ability are enhanced, and long cycle of the solid-state lithium metal battery is realized.

Description

Technical Field

[0001] This invention belongs to the field of solid polymer electrolyte technology, specifically relating to a method for preparing a solid polymer electrolyte based on dynamic dipole compensation and its application. Background Technology

[0002] Solid-state lithium metal batteries are considered a crucial development direction for next-generation high-energy-density and high-safety energy storage systems due to the ultra-high theoretical specific capacity and low redox potential of lithium metal, as well as the potential advantages of solid electrolytes in suppressing leakage, volatilization, and thermal runaway. Solid electrolytes, as the ion transport medium and key carrier at the electrode / electrolyte interface, directly determine the battery's rate performance, cycle life, and safety margin. However, while existing inorganic solid electrolytes possess high room-temperature ionic conductivity and certain mechanical strength, they typically suffer from high brittleness, poor interfacial wettability, processing difficulties, and high interfacial impedance due to poor interfacial contact. Furthermore, they are prone to chemical / electrochemical instability and interfacial void evolution at the lithium metal anode, making it difficult to maintain a stable deposition / stripping process over the long term. In contrast, solid polymer electrolytes (SPEs), with their excellent flexibility, processability, and adaptive adhesion to electrode surfaces, are more likely to form tight interfacial contacts, demonstrating significant engineering application potential. Among them, polyether polymers, represented by PEO, have been extensively studied due to their excellent solubility and coordination ability with lithium salts and have become important matrix materials for constructing polymer solid electrolytes.

[0003] However, PEO-based SPEs have long been constrained in practical applications by the intractable contradiction between room-temperature ionic conductivity and mechanical strength: on the one hand, Li + Migration in PEO depends on the movement of chain segments within the amorphous region and the coordination / decoupling process of ether oxygen sites. At room temperature, the high crystallinity of PEO restricts chain segment movement, resulting in insufficient ionic conductivity, which intensifies concentration polarization and induces uneven deposition. On the other hand, introducing plasticizers, reducing crystallinity, or increasing the proportion of amorphous phase to improve ion transport often sacrifices the material's mechanical support capacity, making the electrolyte more susceptible to local stress concentration and interfacial morphology disturbances, thereby accelerating dendrite initiation and penetration, ultimately leading to short-circuit failure. Furthermore, although strategies such as crosslinking networks, ceramic / inorganic fillers, copolymerization modification, and the construction of artificial interfacial layers can improve strength or interfacial stability to some extent, new trade-offs and side effects are still prevalent: the rigidity introduced by crosslinking restricts chain segment movement and reduces ion migration efficiency; although fillers may increase modulus, they are prone to uneven dispersion, interfacial defects, and local current contraction, thus forming deposition "hot spots"; artificial interfacial layers mostly rely on chemical passivation or physical barriers, which are difficult to continuously adapt to the evolution of interfacial morphology during cycling, and the interfacial impedance may still gradually increase.

[0004] More importantly, existing technologies often attribute dendrite formation to "mechanical deficiencies" or "interfacial side reactions," focusing on suppressing dendrites by increasing modulus, adding physical barriers, or improving chemical stability. However, in many systems, it remains difficult to achieve repeatable long-term stability, indicating that optimization at the macroscopic mechanical or chemical level alone cannot fundamentally eliminate the driving force of dendrite formation. Research and practice show that the nucleation and growth of lithium dendrites are essentially controlled by the migration kinetics of Li⁺ at the interface, and the Li⁺ flux distribution is directly regulated by the electric field (potential) distribution at the electrode / electrolyte interface. Since the surface of solid polymer electrolytes often exhibits microscopic inhomogeneities such as crystallinity, component distribution, polar group density, and local modulus, these inhomogeneities induce differences in interfacial polarization and space charge distribution, forming a non-uniform electrostatic environment with "potential fluctuations." This results in enhanced local electric fields and concentrated ion flux, driving Li⁺ formation. + In specific regions, preferential nucleation and deposition occur, continuously amplifying the initial micro-protrusions, eventually evolving into dendritic penetration. The difficulty of existing technologies lies in the fact that even if the material strength is improved or the interfacial chemical stability is enhanced, if the interfacial potential fluctuations and electric field inhomogeneities are not actively mitigated, local deposition hotspots and dendritic failures may still occur; while simply pursuing "high electrical conductivity" to reduce polarization will further weaken the mechanical support and amplify the interfacial morphology disturbances.

[0005] Therefore, the core bottleneck in the field of PEO-based solid electrolytes is how to actively construct an interface environment with more uniform potential and "milder" electrostatics while maintaining high ion migration efficiency and good interface adhesion, thereby suppressing local Li⁺ aggregation and dendrite initiation from the electrostatic source. Summary of the Invention

[0006] To address the problems existing in the background technology, the present invention aims to provide a method for preparing a solid polymer electrolyte based on dynamic dipole compensation and its application. This invention uses polyurethane epoxy resin and PEO as polymers, which are composited at the molecular scale to form a mechanically interlocked structure. This structure is then modified by doping with MOF-177 material to obtain a novel composite solid polymer electrolyte with "charge balance / dynamic dipole compensation". This invention, through the mechanically interlocked composite structure and the synergistic effect of MOF, constructs a more uniform, near-"charge-neutral" interfacial environment (meaning minimal interfacial potential fluctuations / electrostatic inhomogeneity, not zero potential difference), thereby reducing Li... + Migration barriers, enhancing ion migration and diffusion; uniform interfacial electric field and Li + Increased flux reduces "hot spot" deposition; enhanced interfacial contact stability and anti-dendrying ability enable long-cycle solid-state lithium metal batteries.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A method for preparing a solid polymer electrolyte based on dynamic dipole compensation includes the following steps:

[0009] S1. Mix 1,3,5-tris(4-carboxyphenyl)benzene, zinc salt and N,N-diethylformamide, disperse by ultrasonication, and then carry out hydrothermal reaction to obtain MOF-177 solution;

[0010] S2. The MOF-177 solution in S1 was washed continuously with N,N-diethylformamide and chloroform, then centrifuged to obtain MOF-177 crystals, which were then dried under vacuum and activated by heating to obtain porous MOF-177 powder.

[0011] S3. Add the activated MOF-177 powder obtained in S2 to an organic solvent containing lithium salt and stir to allow the lithium salt to completely permeate inside and outside the MOF cavity, thus obtaining a Li@MOF-177 solution.

[0012] S4. Add polyurethane epoxy resin to the Li@MOF-177 solution obtained in S3 and stir. Then add PEO to obtain a composite electrolyte solution.

[0013] S5. Add persulfate to the composite electrolyte solution to carry out in-situ polymerization and form a composite electrolyte solution with a mechanically interlocked structure;

[0014] S6. Transfer the composite electrolyte solution with mechanical interlocking structure obtained in S5 to a mold, let it stand for a period of time, and then vacuum dry to remove the solvent to obtain the desired solid polymer electrolyte.

[0015] Further, in step S1, the concentration of the 1,3,5-tris(4-carboxyphenyl)benzene solution in the MOF-177 solution is 1-15 mmol / mL, and the zinc salt is zinc nitrate hexahydrate, zinc chloride, zinc sulfate, etc.; the concentration of the zinc salt in the MOF-177 solution is 1-15 mmol / mL.

[0016] Furthermore, in step S1, the hydrothermal reaction time is 12-86 hours and the temperature is 60°C-180°C.

[0017] Furthermore, in step S2, the drying temperature is 30°C-60°C and the time is 6h-12h; the activation treatment temperature is 120°C-180°C and the time is 6h-48h.

[0018] Further, in step S3, the organic solvent is one or more of anhydrous acetonitrile and N,N-methyleneformamide;

[0019] The lithium salt is one or more of bis(trifluoromethanesulfonyl)imide and bis(fluorosulfonate)imide.

[0020] Further, in step S4, MOF-177 accounts for 0.5 wt%-30 wt% of the total amount of polyurethane epoxy resin, PEO and lithium salt; the molar ratio of PEO to lithium salt is (25-6):1; the mass ratio of PEO to polyurethane epoxy resin is (95-50):(5-50).

[0021] Furthermore, steps S3 to S6 are all performed in a vacuum environment.

[0022] Furthermore, in step S5, the in-situ polymerization time is 10h-30h.

[0023] Furthermore, in step S6, the standing time is 6h-34h, and the environment is a vacuum environment; the drying temperature is 40-80℃.

[0024] The present invention also provides the application of the above-mentioned solid polymer electrolyte as an electrolyte in a battery, such as a lithium metal battery, a sodium battery, or a potassium battery.

[0025] The mechanism of this invention is as follows:

[0026] A three-dimensional cross-linked network of polyurethane-epoxy resin was constructed in situ within a continuous PEO phase, and MOF-177 was introduced to form a composite solid-state polymer electrolyte with multi-scale synergistic regulation capabilities. Specifically, the polyurethane-epoxy resin precursor component was progressively cross-linked and cured within the PEO molecular environment, causing the formed three-dimensional network to interpenetrate and topologically entangle with PEO segments at the molecular scale, thereby constructing a mechanically interlocked composite structure resulting from the combined effects of "segment interpenetration—spatial confinement—topological constraint." This structure, on the one hand, maintains the necessary mobility of PEO segments to ensure the Li + On the one hand, transport is facilitated by a continuous framework provided by a cross-linked network, achieving a synergistic unity of "high conductivity and high stability." At the molecular level, ether-oxygen groups in the PEO segments can form dipole-dipole interactions, hydrogen bonds, and coordination interactions with urethane groups, carbonyl groups, ether bonds, and other multipolar functional groups in the polyurethane epoxy resin network, thereby enhancing the non-covalent anchoring effect between the two phases. This multi-interaction not only inhibits large-scale migration and local collapse of PEO segments but also introduces a multi-site synergistic coordination environment based on traditional ether-oxygen coordination, providing a suitable environment for Li... +This provides a more continuous and uniform migration path, reducing the ion migration energy barrier. Furthermore, the introduced MOF-177 is a highly open three-dimensional structure with high long-range order and perfect topology—a (6,3) coordination network composed of octahedral OZn4(CO2)6 clusters connected to triangular BTB ligands. This network structure, by preventing the formation of interpenetrating frameworks after its introduction into the polymer matrix, provides a large interaction interface between polymer segments and lithium salt anions, while the regular channels act as confinement spaces, guiding the distribution of polymer segments and ions. This facilitates the adaptive adjustment of the interfacial charge distribution, thereby homogenizing the local electric field and optimizing the ion migration environment at the microscale. On the one hand, the interfacial coupling between MOF-177 and polymer segments can induce dynamic rearrangement of interfacial dipoles, adaptively adjusting the local charge distribution, thereby reducing potential fluctuations and homogenizing the interfacial electric field at the microscale. On the other hand, the pore structure and surface sites of MOF-177 can adsorb and confine anions (TFSI⁻ / FSI⁻), effectively limiting their migration freedom and weakening Li + – Anion association promotes lithium salt dissociation and increases the proportion of effective current-carrying ions. It is worth emphasizing that the polyurethane epoxy crosslinking network and MOF-177 do not function independently, but rather form a synergistic enhancement effect in terms of structural support, coordination regulation, and interfacial polarization adjustment: the crosslinking network provides stable topological constraints and a multipolar coordination environment, while MOF-177 further enhances interfacial charge regulation and anion confinement capabilities. Together, they construct a "quasi-charge-neutral interface" with a gentle potential distribution and a uniform local electric field. Under these multiple synergistic effects, Li₂ at the interface can be effectively suppressed. + Localized enrichment and uneven deposition reduce the tendency for dendrite initiation and decrease the occurrence of side reactions, thereby significantly improving the rate performance and long-term cycle stability of solid-state batteries. This demonstrates that the present invention, through a combined strategy of "in-situ crosslinking to construct a mechanically interlocked network + MOF-177 interface regulation," achieves structural innovation and functional enhancements in ion transport and interface stability that differ from traditional polymer electrolyte systems.

[0027] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0028] 1. The solid polymer electrolyte proposed in this invention has a simple preparation process, readily available raw materials, and low cost; through dynamic dipole compensation and anion regulation, it actively weakens interfacial potential fluctuations, unifies the electric field, and increases ion flux, suppressing dendrites from the electrostatic source; the mechanically interlocked composite structure enhances framework stability while maintaining chain segment movement, achieving synergy between ion transport and mechanical properties, and reducing Li + It reduces migration barriers, improves diffusion kinetics, and enhances electrolyte ion conductivity and interface stability.

[0029] 2. The solid polymer electrolyte prepared in this application has a special ion transport channel, thus exhibiting high ionic conductivity. At room temperature, the ionic conductivity of the CPEZ of this invention is 5.0 × 10⁻⁶. -4 S / cm, 1.9×10 at 60°C -3 S / cm, PEO (3.9 × 10⁻⁶) at temperatures above 60°C -4 The S / cm ratio is on the order of magnitude; and the ion transference number is 0.71, which can effectively suppress dendrite growth and help extend the cycle life of the battery.

[0030] 3. The all-solid-state symmetric battery assembled based on the solid polymer electrolyte prepared in this application exhibits excellent rate performance; at 0.1 mA / cm 2 After more than 7200 hours of cycling, at 0.2 mA / cm 2 After more than 2000 hours of circulation, the current is 0.2 mA / cm at room temperature. 2 It can be cycled for more than 1600 hours; and the cycle stability is also good. After more than 5000 cycles at 1°C, its retention rate is as high as 90% or more; at room temperature, after 2000 cycles at 1°C, its retention rate is as high as 80% or more.

[0031] 4. The solid polymer electrolyte prepared by this invention has excellent corrosion resistance and a wide electrochemical window of 5.5 V; it is also multifunctional and can be applied to lithium nickel cobalt manganese oxide and lithium iron phosphate systems, and can cycle more than 200 times in lithium nickel cobalt manganese oxide systems, thus having stronger versatility and practicality. Attached Figure Description

[0032] Figure 1 This is a comparison chart of the mechanical properties of the solid polymer electrolytes prepared in Example 1 and Comparative Example 1.

[0033] Figure 2 The image shows a comparison of the LSV linear sweep voltammetry curves of the solid polymer electrolytes prepared in Example 1 and Comparative Example 1.

[0034] Figure 3 The conductivity diagram of the PEO-based solid polymer electrolyte before modification in Comparative Example 1 is shown.

[0035] Figure 4 The conductivity diagram is shown for the solid polymer electrolyte prepared in Example 1 of this invention.

[0036] Figure 5 This is an ion migration diagram of the PEO-based solid polymer electrolyte before modification in Comparative Example 1.

[0037] Figure 6 This is an ion migration diagram of the solid polymer electrolyte prepared in this invention.

[0038] Figure 7 This is a comparison chart of the rate performance of the solid polymer electrolytes prepared in Example 1 and Comparative Example 1 at 60°C.

[0039] Figure 8 The symmetric battery assembled based on the solid polymer electrolytes prepared in Example 1 and Comparative Example 1 was tested at 60°C and 0.1 mA / cm². 2 The following is a comparison chart of the cycle performance.

[0040] Figure 9 The symmetric battery assembled based on the solid polymer electrolyte prepared in this invention achieves 0.2 mA / cm² at room temperature. 2 Performance graph for the next cycle.

[0041] Figure 10 This is a comparison chart of the rate performance of lithium iron phosphate full cells assembled based on the solid polymer electrolytes prepared in Example 1 and Comparative Example 1.

[0042] Figure 11 The graph shows a comparison of the cycling performance of full-cell lithium iron phosphate batteries assembled based on the solid polymer electrolytes prepared in Example 1 and Comparative Example 1 at 60°C and 1C.

[0043] Figure 12 The graph shows the 1C cycling performance of a full-cell lithium iron phosphate battery assembled based on the solid polymer electrolytes prepared in Example 1 and Comparative Example 1 at room temperature.

[0044] Figure 13 The graph shows a comparison of the cycling performance of NCM811 full cells assembled based on the solid polymer electrolytes prepared in Example 1 and Comparative Example 1 at 60°C and 0.2 C. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0046] Example 1

[0047] A method for preparing a solid polymer electrolyte based on dynamic dipole compensation includes the following steps:

[0048] S1. Mix 1,3,5-tris(4-carboxyphenyl)benzene (0.01 mmol), zinc salt (0.03 mmol) and N,N-diethylformamide (40 ml), disperse by sonication for 30 min, and then transfer to a high-pressure reactor for hydrothermal reaction at 120 °C for 24 h to obtain MOF-177 solution;

[0049] S2. The MOF-177 solution in S1 was washed continuously with N,N-diethylformamide (10 ml) and chloroform (10 ml), and then centrifuged to obtain MOF-177 crystals. After drying at 60℃ for 24 h, it was activated by heating at 150℃ for 24 h to remove the adsorbed water in the pores and obtain porous MOF-177 powder.

[0050] S3. Raw material drying: PEO and LiTFSI were dried at 60 °C for 24 h under vacuum conditions.

[0051] S4. Weigh 0.25g of the activated MOF-177 powder obtained in S2 and add it to an organic solvent containing lithium salt. Stir vigorously for 24 hours to allow the lithium salt to completely permeate inside and outside the MOF cavity.

[0052] S5. Add polyurethane epoxy resin to the Li@MOF-177 solution obtained in S3 and stir. Then add 1.5 g PEO to obtain a composite electrolyte solution. The mass ratio of PEO to polyurethane epoxy resin is 80:20, and the molar ratio of PEO to lithium salt is 16:1. MOF-177 accounts for 5 wt% of the total amount of polyurethane epoxy resin, PEO, and lithium salt.

[0053] S6. Add 0.05g of potassium persulfate to the composite electrolyte solution and polymerize in situ for 24 h to form a composite electrolyte with a mechanically interlocked structure.

[0054] S7. Transfer the composite electrolyte solution with mechanical interlocking structure obtained in S6 to the mold, let it stand for 24 h, and then dry it under vacuum at 60°C for 24 h to remove the solvent, so as to obtain the desired CPEZ solid polymer electrolyte.

[0055] The positive electrode material of the all-solid-state battery prepared based on the CPEZ solid polymer electrolyte obtained in this invention is lithium iron phosphate and lithium nickel cobalt manganese oxide, and the negative electrode material is sodium sheet or lithium sheet.

[0056] Example 2

[0057] CPEZ solid polymer electrolyte was prepared according to the steps of Example 1, except that the mass percentage of MOF-177 in step S5 was adjusted to 0.5 wt%, 3 wt%, 10 wt%, 15 wt%, and 30 wt%, while the other steps remained unchanged, to obtain an all-solid electrolyte membrane.

[0058] Comparative Example 1

[0059] 1.5 g of PEO and lithium salt in a molar ratio of 16:1 were added to anhydrous organic solution and stirred for 24 h. The mixture was then transferred to a mold and allowed to stand under vacuum for 24 h to form a film. Subsequently, the film was transferred to a vacuum oven and dried at 60 °C for 24 h to remove the organic solution, thus obtaining an all-solid electrolyte membrane (PEO).

[0060] Comparative Example 2

[0061] Solid polymer electrolytes were prepared according to the steps in Example 1. The potassium persulfate initiation system used in in-situ polymerization was replaced with the photoinitiator diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO), and photopolymerization was carried out under 365 nm ultraviolet light irradiation for 20 min to prepare a composite electrolyte membrane.

[0062] The obtained composite electrolyte membranes were assembled into all-solid-state sodium-ion button batteries and all-solid-state lithium-ion button batteries, respectively, and their electrochemical performance was tested.

[0063] The results show that, compared with Comparative Example 1, the electrolyte prepared in Example 1 exhibits higher ionic conductivity and lithium-ion transference number, as well as lower interfacial polarization and better cycle stability. This indicates that, unlike photoinitiated polymerization which relies on external ultraviolet light and is prone to spatial curing inhomogeneity and local crosslinking differences, the in-situ polymerization method used in Example 1 can achieve uniform initiation and simultaneous crosslinking in the continuous PEO phase. This allows the polyurethane epoxy network to be generated in situ at the molecular scale and fully interpenetrates and entangles with the PEO segments, thereby forming a more uniform and mechanically interlocked composite network with tighter interfacial bonding. This structure not only improves the overall mechanical stability of the system but also constructs more continuous ion migration channels, reduces interfacial resistance and polarization, and further improves electrode / electrolyte interface stability and ion transport capability. This, in turn, enhances the ionic conductivity of the electrolyte and the cycle stability of the battery.

[0064] Comparative Example 3

[0065] Solid polymer electrolyte was prepared according to the steps of Example 1, except that MOF-177 was replaced with CuBTC-MOF, which is formed by 1,3,5-benzenetricarboxylic acid (BTC) and anhydrous copper chloride (CuCl2); the composition, ratio and preparation process of the remaining raw materials were the same as in Example 1, and finally an all-solid electrolyte membrane was prepared.

[0066] The above-described all-solid-state electrolyte membranes were assembled into all-solid-state sodium-ion button batteries and all-solid-state lithium-ion button batteries, and their electrochemical performance was tested. The results showed that, compared with Example 1, the all-solid-state electrolyte membrane prepared using Cu BTC-MOF exhibited decreased overall performance in both types of all-solid-state batteries, manifested as increased interfacial impedance, enhanced polarization, decreased rate performance, and worsened cycle stability. This indicates that the MOF-177 used in Example 1 has a superior effect in optimizing the ion transport environment within the polymer electrolyte and improving the stability of the electrode / electrolyte interface. This is mainly attributed to the highly open three-dimensional structure of MOF-177, which possesses high long-range order and perfect topology—a (6,3) coordination network composed of octahedral OZn4(CO2)6 clusters connected to triangular BTB ligands. This network structure, by preventing the formation of interpenetrating frameworks after its introduction into the polymer matrix, provides a large interaction interface for polymer segments and lithium salt anions, while the regular channels act as confining spaces, guiding the distribution of polymer segments and ions. This is beneficial for inducing adaptive adjustment of the interface charge distribution, thereby homogenizing the local electric field and optimizing the ion migration environment at the microscale.

[0067] Comparative Example 3

[0068] Solid polymer electrolyte was prepared according to the steps of Example 1, except that MOF-177 was replaced with M-BTC-MOF, where M is Co, Mn or Ni. M-BTC-MOF was prepared by reacting 1,3,5-benzenetricarboxylic acid (H3BTC) with the corresponding metal chloride salt CoCl2, MnCl2 or NiCl2. The composition, ratio and preparation process of the remaining raw materials were the same as in Example 1. Finally, an all-solid-state electrolyte membrane was prepared.

[0069] The aforementioned all-solid-state electrolyte membranes were assembled into all-solid-state sodium-ion button batteries and all-solid-state lithium-ion button batteries, respectively, and their electrochemical performance was tested. The results showed that, compared with all-solid-state electrolyte membranes obtained using Co-BTC-MOF, Mn-BTC-MOF, and Ni-BTC-MOF, the all-solid-state electrolyte membrane obtained using MOF-177 in Example 1 exhibited superior overall electrochemical performance, specifically higher ionic conductivity, lower interfacial impedance, smaller charge-discharge polarization, better rate performance, and more stable cycle performance. This indicates that MOF-177 can more effectively regulate the ion transport microenvironment in the polymer matrix, promote the dissociation and migration of current-carrier ions, and improve the stability of the electrode / electrolyte interface. This demonstrates that MOF-177 is not an equivalent component that can be arbitrarily replaced by other M-BTC-MOFs, but plays a crucial role in improving the performance of all-solid-state sodium-ion batteries and all-solid-state lithium-ion batteries.

[0070] To further investigate the corrosion resistance optimization effect of the all-solid polymer electrolyte provided by the present invention, the mechanical properties of the all-solid electrolyte membranes before and after modification in Example 1 and Comparative Example 1 were tested, and the test results are as follows: Figure 1 As shown in the figure, the PEO curve represents the data from Comparative Example 1, and the CPEZ curve represents the data from Example 1. It can be seen from the figure that the mechanical properties of the modified solid electrolyte are significantly improved, increasing from 1.8 MPa to 7 MPa. This significantly enhances the ability to suppress lithium dendrites and improves the electrolyte's cycle performance.

[0071] A coin cell was assembled using the modified and unmodified all-solid-state electrolytes. The coin cell structure consisted of: a positive electrode shell, a gasket, a lithium electrode, an all-solid-state electrolyte, stainless steel, a gasket, a spring contact, and a negative electrode shell. The all-solid-state performance scanning voltammetry results are shown below. Figure 2 As shown in the figure, the electrochemical window of the symmetric battery assembled with the CPEZ electrolyte prepared in this invention is significantly improved, increasing from 4.1V to 5.5V. This effectively solves the problem of the low voltage window of polymer electrolytes, indicating that the electrolyte has a wider electrochemical stability window. This demonstrates that it can maintain structural stability at higher potentials and is not prone to electrochemical decomposition. This is beneficial for reducing side reactions at the electrode / electrolyte interface, improving interface stability, and further enhancing the cycle life and rate performance of the battery, while also expanding its application potential in high-voltage cathode systems.

[0072] A symmetrical button cell was assembled using the all-solid-state electrolyte before and after modification. The button cell structure consisted of: a positive electrode shell, a gasket, stainless steel, an all-solid-state electrolyte, stainless steel, a gasket, a spring, and a negative electrode shell. The electrochemical impedance of the gel was tested, and the ionic conductivity was calculated using the formula σ = L / RS. The results of the electrochemical impedance and ionic conductivity are shown below. Figure 3-4 As shown, the ionic conductivity was significantly improved after optimization, with the modified CPEZ exhibiting an ionic conductivity of 5.0 × 10⁻⁶ at room temperature. –4 S cm –1 At 60℃, the PEO content is 3.9 × 10⁻⁶. –4 S / cm –1 CPEZ is 1.9 × 10 –3 S / cm –1 This effectively solved the problem of poor conductivity in pure PEO polymer electrolytes, laying the foundation for good battery performance in the future.

[0073] A coin cell lithium-ion symmetric battery was assembled using the all-solid-state electrolyte before and after modification. The structure of the coin cell was as follows: positive electrode shell, spacer, lithium sheet, all-solid-state electrolyte, lithium sheet, spacer, spring contact, and negative electrode shell. The electrochemical impedance of the all-solid-state electrolyte was tested. The results are as follows: Figure 5-6As shown, the optimization significantly improved the ion mobility from 0.24 to 0.71, effectively solving the problem of low ion mobility in pure polymer electrolytes. The increase in ion transference number indicates that the current is mainly generated by Li. + (or Na + This process helps reduce concentration polarization caused by anion migration, homogenizes interfacial ion flux, thereby suppressing dendrite growth and improving electrode / electrolyte interface stability, further enhancing the battery's rate performance and cycle life. This lays the foundation for subsequent excellent battery performance.

[0074] The structure of a full-cell coin cell assembled from all-solid-state lithium-ion batteries is as follows: positive electrode shell, lithium iron phosphate electrode, all-solid-state electrolyte, lithium plate, spacer, spring contact, and negative electrode shell. The structure of a full-cell coin cell assembled from all-solid-state sodium-ion batteries is as follows: positive electrode shell, lithium iron phosphate electrode, all-solid-state electrolyte, sodium plate, spacer, spring contact, and negative electrode shell. For symmetrical versions, simply replace the positive electrode with the corresponding sodium / lithium plate.

[0075] Battery testing: The assembled button batteries were charged and discharged on the Blue Battery Testing System, and the remaining electrochemical tests were conducted on the Shanghai Chenhua Electrochemical Workstation.

[0076] The button cell was subjected to rate and long-cycle tests at 60°C and room temperature. The results of its symmetric cell design for all-solid-state lithium-ion batteries are as follows: Figure 7-9 As shown, it can be achieved at 0.1 mA•cm –2 Up to 0.5 mA•cm –2 It can still cycle stably at current densities multiples of [previous value]. Simultaneously, at 0.1 mA•cm [current density]... –2 At a current density of [value missing], it exhibits stable cycling stability for over 7200 hours without short-circuiting. At room temperature, at 0.2 mA•cm [value missing]... –2 The battery can still cycle stably for more than 1600 hours at current density, which indicates that the metal ion deposition / dissolution process of the battery assembled with the all-solid electrolyte is relatively uniform and stable, and the electrochemical window is stable. This prevents the generation of anion concentration gradient, thereby inhibiting the formation of lithium dendrites and the generation of "dead lithium", laying a solid foundation for its reliable application in many fields.

[0077] The button cell was subjected to rate and long-cycle performance tests at 60°C. The results are as follows: Figure 10 As shown, the battery assembled with the modified all-solid-state electrolyte exhibits superior rate performance at 60°C, maintaining a capacity of 145 mAh•g even at a high rate of 1C. –1 Furthermore, the long-term cycling performance of the full cell at 60°C is as follows: Figure 11As shown, after 5000 cycles, the capacity retention rate is as high as 90%, and compared with the unmodified all-solid-state battery, the modified all-solid-state electrolyte has a more stable cycling performance. Secondly, as... Figure 12 As shown, the full battery retains up to 80% of its capacity after 1000 cycles at room temperature.

[0078] Furthermore, the all-solid-state electrolyte provided in this study can operate in a large window voltage and different material systems, and its performance in long-cycle NCM811 materials is as follows: Figure 13 As shown, its volume retention rate can reach 80% after 200 cycles. Its successful operation further confirms the significant practicality of the all-solid-state electrolyte proposed in this study.

[0079] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A method for preparing a solid polymer electrolyte based on dynamic dipole compensation, characterized in that, Includes the following steps: S1. Mix 1,3,5-tris(4-carboxyphenyl)benzene, zinc salt and N,N-diethylformamide, disperse by ultrasonication, and then carry out hydrothermal reaction to obtain MOF-177 solution; S2. The MOF-177 solution in S1 was washed continuously with N,N-diethylformamide and chloroform, then centrifuged to obtain MOF-177 crystals, which were then dried under vacuum and activated by heating to obtain porous MOF-177 powder. S3. Add the activated MOF-177 powder obtained in S2 to an organic solvent containing lithium salt and stir to allow the lithium salt to completely permeate inside and outside the MOF cavity, thus obtaining a Li@MOF-177 solution. S4. Add polyurethane epoxy resin to the Li@MOF-177 solution obtained in S3 and stir. Then add PEO to obtain a composite electrolyte solution. S5. Add persulfate to the composite electrolyte solution to carry out in-situ polymerization and form a composite electrolyte solution with a mechanically interlocked structure; S6. Transfer the composite electrolyte solution with mechanical interlocking structure obtained in S5 to a mold, let it stand in a vacuum environment for a period of time, and then vacuum dry to remove the solvent to obtain the desired solid polymer electrolyte.

2. The preparation method according to claim 1, characterized in that, In step S1, the concentration of the 1,3,5-tris(4-carboxyphenyl)benzene solution in the MOF-177 solution is 1-15 mmol / mL, and the zinc salt is zinc nitrate hexahydrate, zinc chloride, or zinc sulfate; the concentration of the zinc salt in the MOF-177 solution is 1-15 mmol / mL.

3. The preparation method according to claim 1, characterized in that, In step S1, the hydrothermal reaction takes 12-86 hours and the temperature is 60°C-180°C.

4. The preparation method according to claim 1, characterized in that, In step S2, the drying temperature is 30°C-60°C and the time is 6h-12h; the activation treatment temperature is 120°C-180°C and the time is 6h-48h.

5. The preparation method according to claim 1, characterized in that, In step S3, the organic solvent is one or more of anhydrous acetonitrile and N,N-methyleneformamide; the lithium salt is one or more of bis(trifluoromethanesulfonyl)imide and difluorosulfonate imide.

6. The preparation method according to claim 1, characterized in that, In step S4, MOF-177 accounts for 0.5 wt%-30 wt% of the total amount of polyurethane epoxy resin, PEO and lithium salt; the molar ratio of PEO to lithium salt is (25-6):1; the mass ratio of PEO to polyurethane epoxy resin is (95-50):(5-50).

7. The preparation method according to claim 1, characterized in that, Steps S3 to S6 are all performed in a vacuum environment.

8. The preparation method according to claim 1, characterized in that, In step S5, the in-situ polymerization time is 10h-30h.

9. The preparation method according to claim 1, characterized in that, In step S6, the standing time is 6-34 hours, and the environment is a vacuum environment; the drying temperature is 40-80℃.

10. The application of the solid polymer electrolyte obtained by the preparation method according to any one of claims 1-9 as an electrolyte in a battery, wherein the battery is a lithium metal battery, a sodium battery, or a potassium battery.

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