Self-healing polymer solid electrolyte and preparation method and application thereof

Abstract

The application belongs to the technical field of solid-state battery electrolytes, and particularly relates to a self-repairing polymer solid-state electrolyte and a preparation method and application thereof. The preparation method of the self-repairing polymer solid-state electrolyte provided by the application comprises the following steps: mixing a monofunctional polyether monomer and a polyether acrylate crosslinking agent to obtain a crosslinking precursor; mixing the crosslinking precursor, polyethylene oxide, a lithium salt and a main solvent under a protective atmosphere to obtain a polymer base dispersion liquid; mixing the polymer base dispersion liquid, a dynamic covalent bond-containing crosslinking monomer and a Lewis acid site-containing polymerizable monomer, and performing heating and homogenization treatment; after cooling, mixing the obtained liquid with a film-forming plasticizer and a photoinitiator to obtain a prepolymer liquid; and crosslinking and solidifying the prepolymer liquid to obtain the self-repairing polymer solid-state electrolyte. The self-repairing polymer solid-state electrolyte prepared by the application has self-healing capability, high lithium ion transference number, strong dendrite formation prevention capability and high high-temperature electrochemical stability.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery electrolyte technology, specifically relating to a self-healing polymer solid electrolyte, its preparation method, and its application. Background Technology

[0002] Traditional polyethylene oxide (PEO)-based solid-state electrolytes are obtained by blending polyethylene oxide with lithium salts. Due to their good flexibility and ease of film formation, they have attracted much attention in the field of solid-state batteries. However, during long-term battery cycling, traditional PEO-based solid-state electrolytes are highly susceptible to micro-crack damage due to electrode volume expansion. These micro-cracks cannot self-heal, easily leading to lithium dendrite growth and internal short circuits. Furthermore, in traditional PEO-based solid-state electrolytes, free anions migrate rapidly towards the positive electrode under the influence of an electric field, resulting in a decrease in the lithium-ion migration number (LMI). t Li + Typically below 0.3, the large accumulation of anions leads to severe concentration polarization, which in turn exacerbates the formation of lithium dendrites. Traditional polyoxyethylene solid electrolytes have a narrow high-temperature electrochemical stability window and are prone to oxidative decomposition below 4.0V under high-temperature cycling conditions such as 60℃. Summary of the Invention

[0003] The purpose of this invention is to provide a self-healing polymer solid electrolyte, its preparation method, and its applications. The self-healing polymer solid electrolyte prepared by the method provided by this invention possesses self-healing capabilities, high lithium-ion transference number, strong anti-dendrying ability, and high high-temperature electrochemical stability.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a self-healing polymer solid electrolyte includes the following steps: A crosslinking precursor is obtained by mixing a monofunctional polyether monomer with a polyether acrylate crosslinking agent. Under a protective atmosphere, the crosslinking precursor, polyethylene oxide, lithium salt and main solvent are mixed to obtain a polymer-based dispersion; The polymer base dispersion, the crosslinking monomer containing dynamic covalent bonds, and the polymerizable monomer containing Lewis acid sites are mixed and heated for homogenization. After cooling, the resulting liquid is mixed with a film-forming plasticizer and a photoinitiator to obtain a prepolymer liquid. The prepolymer liquid is crosslinked and cured to obtain the self-healing polymer solid electrolyte.

[0005] Preferably, the monofunctional polyether monomer includes polyethylene glycol monomethyl ether methacrylate; the polyether acrylate crosslinking agent includes polyethylene glycol diacrylate; and the mass ratio of the monofunctional polyether monomer to the polyether acrylate crosslinking agent is 1:0.25~7.

[0006] Preferably, the lithium salt comprises a primary lithium salt and a secondary lithium salt, the primary lithium salt comprising lithium bis(trifluoromethanesulfonyl)imide, and the secondary lithium salt comprising lithium difluorooxalateborate; the primary solvent comprises acetonitrile; the mass ratio of polyethylene oxide, primary lithium salt, and secondary lithium salt is 1:0.18~0.25:0.01~0.03; the amount ratio of polyethylene oxide to primary solvent is 0.6~0.8g:7.5~9mL; and the mass ratio of polyethylene oxide to crosslinking precursor is 0.6~0.8:0.1~0.2.

[0007] Preferably, the crosslinking monomer containing dynamic covalent bonds includes bisacrylamidocystamine; the polymerizable monomer containing Lewis acid sites includes 4-vinylphenylboronic acid; and the mass ratio of the crosslinking monomer containing dynamic covalent bonds to the polymerizable monomer containing Lewis acid sites is 1:0.5~0.8.

[0008] Preferably, the heating homogenization treatment is performed at a temperature of 40-50°C for 10-14 hours.

[0009] Preferably, the film-forming plasticizer includes fluoroethylene carbonate, and the photoinitiator includes 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone; the mass ratio of the film-forming plasticizer to the photoinitiator is 0.12~0.15:0.01~0.02.

[0010] Preferably, the crosslinking curing is carried out under ultraviolet light irradiation, the wavelength of the ultraviolet light is 365~380nm, and the crosslinking curing includes a first crosslinking curing and a second crosslinking curing, the time for the first crosslinking curing and the second crosslinking curing is independently 10~25min.

[0011] The present invention provides a self-healing polymer solid electrolyte prepared by the preparation method described above, comprising a comb-like topological network and in-situ bonded dynamic covalent bonds and Lewis acid sites in the comb-like topological network.

[0012] Preferably, the dynamic covalent bond is a reversible dynamic disulfide bond, and the Lewis acid site is a boron atom.

[0013] This invention provides the application of the self-healing polymer solid electrolyte described above in solid-state lithium batteries; the solid-state lithium batteries include solid-state lithium-ion batteries, solid-state lithium metal batteries, flexible solid-state lithium-ion batteries, and flexible solid-state lithium metal batteries.

[0014] The method for preparing the self-healing polymer solid electrolyte provided by this invention constructs a highly asymmetric comb-like crosslinking network by crosslinking a monofunctional polyether monomer with a polyether acrylate crosslinking agent. The long, flexible polyether chains of the monofunctional polyether monomer effectively disrupt the regular arrangement of the PEO molecular chains thermodynamically, providing ample amorphous channels for rapid lithium-ion transport.

[0015] The addition of a dynamically covalently crosslinked monomer in this invention introduces dynamic covalent bonds that act as dynamic exchange nodes in the network. When the electrolyte is subjected to mechanical shearing, the dynamic covalent bonds can undergo reversible breakage and recombination under microthermal drive, achieving autonomous healing of macroscopic and microscopic cracks. Moreover, after undergoing multiple shearing and healing processes, its impedance and ionic conductivity can still maintain a high degree of stable recovery rate, fundamentally changing the fate of traditional solid electrolytes where damage equals failure.

[0016] The polymerizable monomer containing Lewis acid sites added in this invention provides Lewis acid sites and strongly electronegative anions (such as TFSI). - Specific coordination occurs, greatly limiting the disordered migration of anions. At 60℃, the lithium-ion transference number is significantly increased to over 0.84, fundamentally eliminating concentration polarization-driven lithium dendrite growth.

[0017] Furthermore, by adding a film-forming plasticizer and a co-lithium salt, the present invention preferentially decomposes under high-pressure cycling, synergistically constructing an extreme high-temperature and high-pressure passivation interface to generate a robust passivation layer rich in inorganic components in situ. This successfully broadens the electrochemical stability window of the solid electrolyte to 5.25V at 60°C, breaking through the high-pressure application limit of polymer electrolytes.

[0018] The self-healing polymer solid electrolyte prepared by the preparation method provided in this invention has the ability to heal itself, high lithium-ion transference number, strong anti-dendritic formation ability, and high high-temperature electrochemical stability, and can be used in solid-state batteries. Attached Figure Description

[0019] Figure 1 Comparison of the macroscopic morphology of the self-healing polymer solid electrolyte prepared in Example 1 after severance and after self-healing. Figure 2 Electrochemical impedance spectroscopy (EIS) spectra of the self-healing polymer solid electrolyte prepared in Example 1 under different temperature conditions; Figure 3 The electrochemical impedance spectroscopy (EIS) and a magnified view of the self-healing polymer solid electrolyte prepared in Example 1 at 60°C, as well as the ionic conductivity after undergoing different healing cycles, are shown. Figure 4Arrhenius curves comparing the temperature-dependent ionic conductivity of the self-healing polymer solid electrolyte prepared in Example 1 after different cut-and-heal cycles at different temperatures. Figure 5 Chorometric amperometry curves and AC impedance spectra before and after polarization of the self-healing polymer solid electrolyte prepared in Example 1 at 60°C; Figure 6 Linear sweep voltammetry (LSV) curves of the self-healing polymer solid electrolyte prepared in Example 1 and the pure PEO electrolyte prepared in Comparative Example 1 at 60°C. Detailed Implementation

[0020] This invention provides a method for preparing a self-healing polymer solid electrolyte, comprising the following steps: A crosslinking precursor is obtained by mixing a monofunctional polyether monomer with a polyether acrylate crosslinking agent. Under a protective atmosphere, the crosslinking precursor, polyethylene oxide, lithium salt and main solvent are mixed to obtain a polymer-based dispersion; The polymer base dispersion, the crosslinking monomer containing dynamic covalent bonds, and the polymerizable monomer containing Lewis acid sites are mixed and heated for homogenization. After cooling, the resulting liquid is mixed with a film-forming plasticizer and a photoinitiator to obtain a prepolymer liquid. The prepolymer liquid is crosslinked and cured to obtain the self-healing polymer solid electrolyte.

[0021] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0022] This invention mixes a monofunctional polyether monomer with a polyether acrylate crosslinking agent to obtain a crosslinking precursor. In one embodiment of this invention, the monofunctional polyether monomer includes monofunctional polyether monomers containing vinyl, acrylate, or methacrylate groups, and further includes polyethylene glycol monomethyl ether methacrylate; the polyether acrylate crosslinking agent includes polyethylene glycol diacrylate; the mass ratio of the monofunctional polyether monomer to the polyether acrylate crosslinking agent is 1:0.25~7, specifically 1:0.25, 1:0.33, or 1:0.5.

[0023] As one embodiment of the present invention, before mixing the monofunctional polyether monomer and the polyether acrylate crosslinking agent, the method further includes: purifying the monofunctional polyether monomer and the polyether acrylate crosslinking agent separately to remove the polymerization inhibitor contained therein; the purification includes column chromatography purification, and the column chromatography includes a dry neutral alumina micro-column chromatography column.

[0024] In this invention, under a protective atmosphere, the crosslinking precursor, polyethylene oxide, lithium salt, and main solvent are mixed to obtain a polymer-based dispersion. As one embodiment of this invention, the polyethylene oxide has a molecular weight of 600,000 to 4,000,000, more specifically 1,000,000 to 2,000,000, and more specifically 1,000,000; the lithium salt includes a main lithium salt and a secondary lithium salt, the main lithium salt including lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), the secondary lithium salt including lithium difluorooxalateborate (LiDFOB), and the main solvent including acetonitrile, specifically anhydrous acetonitrile. The mass ratio of polyethylene oxide, main lithium salt, and auxiliary lithium salt is 1:0.18~0.25:0.01~0.03, specifically 1:0.21:0.016; the amount ratio of polyethylene oxide to main solvent is 0.6~0.8g:7.5~9mL, specifically 0.6g:7.5mL; the mass ratio of polyethylene oxide to crosslinking precursor is 0.6~0.8:0.1~0.2, specifically 0.6:0.15.

[0025] In one embodiment of the present invention, the protective atmosphere includes argon gas with a purity ≥99.999%; the crosslinking precursor, polyethylene oxide, lithium salt and main solvent are mixed to form a first mixture, the first mixture is magnetically stirred, the stirring speed is 300~400 rpm, specifically 350 rpm, the temperature of the first mixture is 20~25℃, and the time is 30~50 min, specifically 40 min.

[0026] After obtaining the polymer-based dispersion, the present invention mixes the polymer-based dispersion, a crosslinking monomer containing dynamic covalent bonds, and a polymerizable monomer containing Lewis acid sites, and performs a heating homogenization treatment. After cooling, the resulting solution is mixed with a film-forming plasticizer and a photoinitiator to obtain a prepolymer solution. As one embodiment of the present invention, the crosslinking monomer containing dynamic covalent bonds includes a polymerizable vinyl monomer containing dynamic covalent bonds, wherein the dynamic covalent bonds in the crosslinking monomer include disulfide bonds, diselenide bonds, or dynamic imine bonds. In the present invention, the crosslinking monomer containing dynamic covalent bonds includes bisacrylamidocystamine. The polymerizable monomer containing Lewis acid sites includes a polymerizable vinyl monomer containing Lewis acid sites, wherein the Lewis acid sites include electron-deficient boron atoms. In the present invention, the polymerizable monomer containing Lewis acid sites includes 4-vinylphenylboronic acid. The mass ratio of the crosslinking monomer containing dynamic covalent bonds to the polymerizable monomer containing Lewis acid sites is 1:0.5~0.8, specifically 1:5, 1:0.67, or 1:8.

[0027] As one embodiment of the present invention, the mixing of the polymer base dispersion, the monomer containing dynamic covalent bonds and the polymerizable monomer containing Lewis acid sites preferably includes: first mixing the polymerizable monomer containing Lewis acid sites and the monomer containing dynamic covalent bonds with tetrahydrofuran, then ultrasonicating the mixture, and then mixing the ultrasonicated mixture with the polymer base dispersion; the ultrasonication temperature is 25~30℃ and the time is 20~25min.

[0028] In one embodiment of the present invention, the temperature of the heating homogenization treatment is 40~50℃, specifically 40℃, 45℃ or 50℃, and the time is 8~14h, or more specifically 8~12h; the heating rate from room temperature to the heating homogenization treatment temperature is 2~5℃ / min.

[0029] In one embodiment of the present invention, the obtained liquid is mixed with a film-forming plasticizer and a photoinitiator to form a second mixture. The cooling is performed by natural cooling to room temperature. The film-forming plasticizer includes fluoroethylene carbonate (FEC), and the photoinitiator includes 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (Irgacure). 2959); the mass ratio of the film-forming plasticizer to the photoinitiator is 0.12~0.15:0.01~0.04, further 0.12:0.01~0.033, specifically 0.12:0.0165, 0.12:0.0198 or 0.12:0.033; preferably, the photoinitiator is dissolved in anhydrous acetonitrile, and the resulting photoinitiator solution is added, the concentration of the photoinitiator solution can be 15~35 mg / mL, specifically 16.5 mg / mL, 19.8 mg / mL or 33 mg / mL; the second mixing is stirring, the second mixing is carried out at room temperature and in the dark, for 30 min.

[0030] After obtaining the prepolymer liquid, the present invention performs crosslinking and curing on the prepolymer liquid to obtain the self-healing polymer solid electrolyte. As one embodiment of the present invention, before the crosslinking and curing, the method further includes: pouring the prepolymer liquid into a mold and allowing it to stand; the mold is made of polytetrafluoroethylene (PTFE); the standing is carried out under oxygen-free and light-protected conditions; the standing temperature is room temperature; and the time is 20-24 hours; the present invention achieves solvent evaporation through standing. In one embodiment of the present invention, the crosslinking curing is carried out under ultraviolet light irradiation, the wavelength of which is 365~380nm. The crosslinking curing includes a first crosslinking curing and a second crosslinking curing, the time for which the first crosslinking curing and the second crosslinking curing are independent is 10~25min. The first crosslinking curing is performed by irradiating the front side of the mold with ultraviolet light, and the second crosslinking curing is performed by irradiating the back side of the mold with ultraviolet light. After the crosslinking curing, vacuum drying is further performed, the temperature of which is 45~50℃ and the drying time is 20~28h. The present invention removes residual solvent by vacuum drying.

[0031] This invention provides a self-healing polymer solid electrolyte prepared by the preparation method described above, comprising a comb-like topological network and in-situ bonded dynamic covalent bonds and Lewis acid sites within the comb-like topological network. In one embodiment of this invention, the dynamic covalent bonds are reversible dynamic disulfide bonds, and the Lewis acid sites are boron atoms. The self-healing polymer solid electrolyte prepared by this invention can achieve multiple reversible self-healing processes through thermal stimulation (40-60°C) after macroscopic or microscopic cleavage.

[0032] This invention provides the application of the self-healing polymer solid electrolyte described above in solid-state lithium batteries; the solid-state lithium batteries include solid-state lithium-ion batteries, solid-state lithium metal batteries, flexible solid-state lithium-ion batteries, and flexible solid-state lithium metal batteries.

[0033] The present invention provides a solid-state battery, comprising a positive electrode, a negative electrode, and a self-healing polymer solid electrolyte as described in the above technical solution; the positive electrode comprises a positive electrode active material.

[0034] In one embodiment of the present invention, the positive electrode active material includes one or more of lithium iron phosphate (LFP), lithium cobalt oxide (LCO), nickel cobalt manganese ternary material (NCM), or lithium manganese oxide (LMO), with lithium iron phosphate being preferred in the present invention; the negative electrode includes a lithium metal negative electrode, a graphite negative electrode, or a silicon-based composite negative electrode, with lithium metal being preferred in the present invention.

[0035] To further illustrate the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments thereof. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0036] The raw materials and reagents used in this invention were all purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; the characteristics of the raw materials, reagents and parameters used in this invention are shown in Table 1.

[0037] Table 1. Parameter characteristics of each raw material and reagent

[0038] Example 1 (1) Polyethylene glycol monomethyl ether methacrylate (PEGMA) and polyethylene glycol diacrylate (PEGDA) were purified by passing them through a dry neutral alumina micro chromatography column to remove the polymerization inhibitor, and purified PEGMA and purified PEGDA were obtained. 0.10 g of purified PEGMA and 0.05 g of purified PEGDA were weighed as crosslinking precursors.

[0039] (2) In an argon atmosphere (purity ≥ 99.999%), 7.5 mL of anhydrous acetonitrile was added to a 20 mL glass main reaction flask protected from light. Then, 0.60 g of polyethylene oxide (PEO, mass-average molecular weight Mw of 1,000,000), 0.13 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 0.01 g of lithium difluorooxalate borate (LiDFOB) and the crosslinking precursor were added. The mixture was magnetically stirred at 350 rpm for 40 min at 25 °C to obtain a polymer-based dispersion.

[0040] (3) Add 0.10 g of 4-vinylphenylboronic acid (4-VPBA) and 0.15 g of bisacrylamidocystamine (BAC) to 3.5 mL of tetrahydrofuran (THF) and sonicate at 30 °C for 20 min. After the monomer is completely dissolved, add the resulting solution to the polymer base dispersion. Seal the reaction flask and heat it to 45 °C for constant temperature stirring for 8 h. After it cools down to room temperature, add 0.12 g of fluoroethylene carbonate (FEC) and 1 mL of anhydrous acetonitrile mother liquor containing 16.5 mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (Irgacure 2959) and stir at room temperature in the dark for 30 min to obtain the prepolymer solution.

[0041] (4) In an oxygen-free glove box, the prepolymer liquid is transferred to a horizontally placed polytetrafluoroethylene (PTFE) mold and left to stand at room temperature in the dark for 24 hours. Then, it is placed under a 365nm ultraviolet lamp for vertical irradiation for 10 minutes, and then flipped over for another 10 minutes. It is then transferred to a vacuum drying oven and vacuum dried at 45°C for 24 hours. The film is then peeled off to obtain a self-healing polymer solid electrolyte, named SHSPE.

[0042] Example 2 Step (1) is basically the same as in Example 1, except that 0.21g of purified PEGMA and 0.09g of purified PEGDA are weighed as crosslinking precursors.

[0043] Step (2) is the same as in Example 1.

[0044] Step (3) is basically the same as in Example 1, except that 0.20g of bisacrylamidocystamine (BAC) is added, and the mass ratio of bisacrylamidocystamine to 4-vinylphenylboronic acid is 1:0.5; 1mL of anhydrous acetonitrile mother liquor containing 19.8mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone is added.

[0045] Step (4) is the same as in Example 1.

[0046] Example 3 Step (1) is basically the same as in Example 1, except that 0.4g of purified PEGMA and 0.1g of purified PEGDA are weighed as crosslinking precursors.

[0047] Step (2) is the same as in Example 1.

[0048] Step (3) is basically the same as in Example 1, except that 0.12g of 4-vinylphenylboronic acid (4-VPBA) is added, the mass ratio of bisacrylamidocystamine to 4-vinylphenylboronic acid is 1:0.8; and 1mL of anhydrous acetonitrile mother liquor containing 33.0mg of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone is added.

[0049] Step (4) is the same as in Example 1.

[0050] Comparative Example 1 Pure PEO solid electrolyte was prepared by solution casting method: 0.60 g of polyethylene oxide (PEO, mass-average molecular weight Mw of 1,000,000) and 0.14 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were added to 14 mL of anhydrous acetonitrile. The reaction mixture of ethylene oxide units and Li was controlled. + The molar ratio was 16:1; the mixture was magnetically stirred at 650 rpm for 8 hours at room temperature to obtain a mixture; the mixture was poured into a polytetrafluoroethylene (PTFE) petri dish, placed in a vacuum drying oven, and vacuum dried at 60°C for 24 hours. The film was then removed to obtain pure PEO solid electrolyte.

[0051] Comparative Example 2 Step (1) is the same as in Example 1.

[0052] Step (2) is basically the same as in Example 1, except that the addition of lithium difluorooxalate borate (LiDFOB) is omitted.

[0053] Step (3) is basically the same as in Example 1, except that the addition of bisacrylamidocystamine, 4-vinylphenylboronic acid and fluoroethylene carbonate is omitted, and anhydrous acetonitrile mother liquor of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone is directly added to the polymer base dispersion.

[0054] Step (4) is the same as in Example 1.

[0055] Comparative Example 3 Step (1) is the same as in Example 1.

[0056] Step (2) is basically the same as in Example 1, except that the addition of lithium difluorooxalate borate (LiDFOB) is omitted.

[0057] Step (3) is basically the same as in Example 1, except that the addition of 4-vinylphenylboronic acid and fluoroethylene carbonate is omitted. Instead, 0.15g of BAC is dissolved in THF and added to the polymer base dispersion, and then only anhydrous acetonitrile mother liquor of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone is added.

[0058] Step (4) is the same as in Example 1.

[0059] Comparing Example 1 and Comparative Examples 2-3 reveals a significant synergistic effect among 4-VPBA, LiDFOB, and FEC in Example 1. The combined introduction of these three components effectively improves the ion transport environment within the solid electrolyte and significantly enhances the interfacial compatibility between the solid electrolyte and the lithium metal anode, effectively reducing interfacial impedance and thus substantially improving the interfacial stability and overall cycle performance of the lithium battery.

[0060] Test Example 1 Comparing the macroscopic morphology of the self-healing polymer solid electrolyte prepared in Example 1 after cleavage and after self-healing, the results are as follows: Figure 1 As shown. Figure 1 These are comparison images of the macroscopic morphology of the self-healing polymer solid electrolyte prepared in Example 1 after cleavage and after self-healing. Figure 1 In the diagram, (a) and (b) are two parallel experiments. Figure 1 Images (a) and (b) show the macroscopic morphology of the self-healing polymer solid electrolyte prepared in Example 1 after cleavage. Figure 1 Image (c) shows the macroscopic morphology of the self-healing polymer solid electrolyte in image (a) after it has been cut and self-healed. Figure 1 (d) is a macroscopic morphology diagram of the self-healing polymer solid electrolyte in (b) after it has been cut and self-healed.

[0061] according to Figure 1It can be seen that after the self-healing polymer solid electrolyte film is cut ( Figure 1 The incisions shown in red circles in (a) and (b) can achieve seamless fusion under 60°C thermal stimulation. Figure 1 The healing zones shown in red circles in (c) and (d) demonstrate that the macroscopic integrity has been fully restored, which intuitively proves that the dynamic covalent bonds introduced into the system endow the electrolyte with excellent macroscopic intrinsic self-repair capability.

[0062] The electrochemical impedance spectroscopy (EIS) spectra of the self-healing polymer solid electrolyte prepared in Example 1 were measured under different temperature conditions, and the results are as follows: Figure 2 As shown. Figure 2 Electrochemical impedance spectroscopy (EIS) spectra of the self-healing polymer solid electrolyte prepared in Example 1 under different temperature conditions. Figure 2 As can be seen, as the temperature increases from 30℃ to 70℃, the impedance semicircle of the solid electrolyte material (its own internal impedance) in Example 1 decreases significantly, showing a trend of substantial impedance reduction. This indicates that the mobility of the polymer comb-like flexible chain segments is further enhanced under the conditions of 30~70℃, greatly promoting the rapid migration of lithium ions; at the same time, under various test temperatures from 30~70℃, the internal network of the self-healing polymer solid electrolyte system is uniform, and ion transport is extremely stable.

[0063] The AC impedance spectra of the self-healing polymer solid electrolyte prepared in Example 1 at 60°C and its ionic conductivity after undergoing different cleavage-healing cycles were measured, and the results are as follows: Figure 3 As shown. Figure 3 The electrochemical impedance spectroscopy (EIS) and a magnified view of the self-healing polymer solid electrolyte prepared in Example 1 at 60°C. Figure 3 The samples that underwent a single incision correspond to the following: Figure 1 The self-healing polymer solid electrolyte films shown in (a) and (b) correspond to the following after self-healing: Figure 1 The complete healing status of (c) and (d). Figure 3 The conductivity can be calculated from its magnified partial image. The conductivity is calculated as follows: through... Figure 3 The bulk resistance (Rb) of the sample is obtained by the intercept of the impedance spectral line intersecting the real axis (Z' axis) in (and the enlarged view). Then, combined with the sample thickness (L) and electrode contact area (S), it is calculated using the formula σ = L / (Rb·S). Figure 3 From the magnified images, it can be concluded that the ionic conductivity of the original (Virgin) self-healing polymer solid electrolyte film is 2.89 × 10⁻⁶ at 60℃. -4 S / cm; after a single incision and a second incision followed by healing (Healed 2) ndAfter that, its ionic conductivity remained stable at 2.40 × 10⁻⁶. -4 S / cm up to 2.65×10 -4 The S / cm level indicates that the intercept of the AC impedance spectrum of the solid electrolyte changes very little after single and multiple cuts, demonstrating the material's excellent dynamic self-healing ability. Furthermore, at 60℃, despite undergoing multiple damage and healing processes, its ionic conductivity remains efficiently maintained at 2.40~.89×10⁻⁶. -4 The high S / cm level proves that the self-healing process does not damage the continuous network structure and ion transport channels inside the material, and has excellent cycle life and stability. Figure 3 The state and conductivity of each sample are shown in Table 2.

[0064] Table 2 Figure 3 State and conductivity of each sample

[0065] Where: σ = L / (Rb·S), L: thickness of PEO solid electrolyte membrane; S: area of ​​PEO solid electrolyte membrane (3.14 × 0.79 × 0.79 = 1.959674 cm²). 2 Rb: The internal impedance of the solid electrolyte material itself.

[0066] Comparative Example 1: The temperature-dependent ionic conductivity of the self-healing polymer solid electrolyte prepared under different cutting and healing processes at different temperatures. Figure 4 Arrhenius curves comparing the temperature-dependent ionic conductivity of the self-healing polymer solid electrolyte prepared in Example 1 after different cleavage healing processes at different temperatures. Figure 4 It can be seen that the original state (Virgin), the first cut healing (Healed 1) st Second transection healing (Healed 2) nd ) and third-degree transection healing (Healed 3) rd The self-healing polymer solid electrolyte exhibited highly consistent conductivity-temperature dependence across the entire test temperature range (30~70℃). This demonstrates that the system not only achieved macroscopic physical healing but also perfectly reconstructed its internal amorphous topological network for rapid lithium-ion transport, ensuring long-term battery operation even under repeated mechanical damage.

[0067] Figure 5 Chorometric amperometry curves and AC impedance spectra before and after polarization of the self-healing polymer solid electrolyte prepared in Example 1 at 60°C; Figure 5 In Figure a, the chronoamperometry curve of the self-healing polymer solid electrolyte prepared in Example 1 at 60°C is shown. Figure 5Image b shows the AC impedance spectra of the self-healing polymer solid electrolyte prepared in Example 1 before and after polarization at 60°C. Figure 5 It can be seen that, under constant potential polarization testing at 60℃, the ratio of steady-state current (Is=1.11μA) to initial current (I0=1.21μA) in Example 1 is relatively high. Based on impedance fitting calculations before and after polarization, its lithium-ion transference number (…) t Li + The value is as high as 0.85. This confirms that the electron-deficient boron atoms in polymerizable monomers containing Lewis acid sites affect TFSI. - The anions produced an extremely effective anchoring effect, preventing the disordered migration of anions and releasing a massive amount of free lithium ions, thereby fundamentally eliminating the concentration polarization-driven growth of lithium dendrites.

[0068] Figure 6 Linear sweep voltammetry (LSV) curves of the self-healing polymer solid electrolyte prepared in Example 1 and the pure PEO electrolyte prepared in Comparative Example 1 at 60°C. Figure 6 It can be seen that the pure PEO electrolyte exhibits a significant oxidation current starting at 4.0V; while in Example 1, the oxidation decomposition potential of SHSPE is significantly delayed until 5.25V before a significant irreversible polarization current appears. This demonstrates that an extremely robust high-voltage solid electrolyte passivation film was successfully constructed in situ at the electrode interface using a comb-like crosslinking network and an interface optimizer, breaking through the high-voltage application limits of traditional polymer electrolytes.

[0069] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a self-healing polymer solid electrolyte, comprising the following steps: A crosslinking precursor is obtained by mixing a monofunctional polyether monomer with a polyether acrylate crosslinking agent. Under a protective atmosphere, the crosslinking precursor, polyethylene oxide, lithium salt and main solvent are mixed to obtain a polymer-based dispersion; The polymer base dispersion, the crosslinking monomer containing dynamic covalent bonds, and the polymerizable monomer containing Lewis acid sites are mixed and heated for homogenization. After cooling, the resulting liquid is mixed with a film-forming plasticizer and a photoinitiator to obtain a prepolymer liquid. The prepolymer liquid is crosslinked and cured to obtain the self-healing polymer solid electrolyte.

2. The preparation method according to claim 1, characterized in that, The monofunctional polyether monomer includes polyethylene glycol monomethyl ether methacrylate; the polyether acrylate crosslinking agent includes polyethylene glycol diacrylate; the mass ratio of the monofunctional polyether monomer to the polyether acrylate crosslinking agent is 1:0.25~7.

3. The preparation method according to claim 1, characterized in that, The lithium salt includes a primary lithium salt and a secondary lithium salt. The primary lithium salt includes lithium bis(trifluoromethanesulfonyl)imide, and the secondary lithium salt includes lithium difluorooxalateborate. The primary solvent includes acetonitrile. The mass ratio of polyethylene oxide, primary lithium salt, and secondary lithium salt is 1:0.18~0.25:0.01~0.

03. The amount ratio of polyethylene oxide to primary solvent is 0.6~0.8g:7.5~9mL, and the mass ratio of polyethylene oxide to crosslinking precursor is 0.6~0.8:0.1~0.

2.

4. The preparation method according to claim 1, characterized in that, The crosslinking monomer containing dynamic covalent bonds includes bisacrylamidocystamine; the polymerizable monomer containing Lewis acid sites includes 4-vinylphenylboronic acid; the mass ratio of the crosslinking monomer containing dynamic covalent bonds to the polymerizable monomer containing Lewis acid sites is 1:0.5~0.

8.

5. The preparation method according to claim 1, characterized in that, The heating and homogenization treatment is carried out at a temperature of 40-50°C for 10-14 hours.

6. The preparation method according to claim 1, characterized in that, The film-forming plasticizer includes fluoroethylene carbonate, and the photoinitiator includes 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone; the mass ratio of the film-forming plasticizer to the photoinitiator is 0.12~0.15:0.01~0.

02.

7. The preparation method according to claim 1, characterized in that, The crosslinking curing is carried out under ultraviolet light irradiation, the wavelength of which is 365~380nm. The crosslinking curing includes a first crosslinking curing and a second crosslinking curing, and the time for the first crosslinking curing and the second crosslinking curing is independently 10~25min.

8. The self-healing polymer solid electrolyte prepared by the preparation method according to any one of claims 1 to 7 includes a comb-like topological network and in-situ bonded dynamic covalent bonds and Lewis acid sites in the comb-like topological network.

9. The self-healing polymer solid electrolyte according to claim 8, characterized in that, The dynamic covalent bond is a reversible dynamic disulfide bond, and the Lewis acid site is a boron atom.

10. The application of the self-healing polymer solid electrolyte of claim 8 or 9 in a solid-state lithium battery; wherein the solid-state lithium battery includes a solid-state lithium-ion battery, a solid-state lithium metal battery, a flexible solid-state lithium-ion battery, and a flexible solid-state lithium metal battery.

Images