A block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design, its preparation method and application

Abstract

This invention provides a block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design. The block copolymer solid electrolyte is a polymer layer with gradient rigidity along the thickness direction. Each polymer layer has an A-B-C type block copolymer, where block A is a monomer of olefin derivative with at least one benzene ring substituent, block B is a crosslinking agent, and block C is an ion-coupled monomer. The gradient rigidity between polymer layers is adjusted by changing the ratio of each block in the A-B-C type block copolymer. This invention achieves comprehensive optimization of monomer solubility, polymerization behavior, network structure, interfacial interaction, and self-healing function, constructing a three-dimensional polymer electrolyte network with high ion conduction efficiency, excellent mechanical strength, stable and reliable interface, and self-healing ability, providing a key molecular engineering solution for overcoming the performance bottleneck of solid-state batteries.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte technology for lithium-ion batteries, and particularly to a block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design, its preparation method, and its application. Background Technology

[0002] The continuous advancement of energy storage technology is profoundly impacting the development of modern industry and society, especially in key areas such as electric vehicles, portable electronic devices, and large-scale energy storage systems. As end-use applications place higher demands on battery performance, traditional lithium-ion battery systems face increasingly severe technological bottlenecks, urgently requiring breakthroughs in energy density, power characteristics, and safety. Against this backdrop, solid-state batteries, as a core direction for next-generation high-safety, high-energy-density battery technology, have received widespread attention from academia and industry.

[0003] Based on different material systems, solid-state electrolytes can be mainly divided into three categories: inorganic ceramic electrolytes, sulfide glass electrolytes, and polymer electrolytes. While inorganic ceramic electrolytes possess high ionic conductivity and chemical stability, their high brittleness, poor interfacial contact, and high processing difficulty limit their commercialization. In contrast, polymer electrolytes, with their good flexibility, excellent interfacial compatibility, and solution processability, exhibit unique advantages in flexible batteries and wearable devices, becoming important candidate materials with both practicality and development potential. Polyethylene oxide (PEO)-based electrolytes are widely studied due to the strong solvation ability of their ether oxygen units for lithium ions and their ease of forming complexes with lithium salts (such as LiTFSI). However, this system still faces two fundamental technical contradictions: on the one hand, PEO segments easily crystallize at room temperature, leading to limited ion migration channels and low room-temperature ionic conductivity, which is difficult to meet practical application requirements; on the other hand, as a homopolymer material, its low Young's rigidity is insufficient to effectively suppress lithium dendrite penetration, creating a "trade-off" dilemma between mechanical strength and ion conduction efficiency.

[0004] To address the aforementioned shortcomings, block copolymer strategies have been proposed and gradually developed into an effective molecular engineering solution. By constructing "AB"-type amphiphilic block structures, functional separation and synergy can be achieved at the nanoscale: the lithiophilic block (A segment) typically consists of flexible chains containing ether oxygen or carbonate functional groups, responsible for providing solvation sites and transport channels for lithium ions; while the lithiophore block (B segment) introduces aromatic rings, rigid frameworks, or other high glass transition temperature (Tg) units to construct a continuous mechanical support network, enhancing overall mechanical rigidity. This functionally separated structural design not only retains good ion conduction potential but also enhances the material's resistance to dendrite formation through a phase separation mechanism.

[0005] Despite these challenges, block copolymer electrolytes still face multiple technical hurdles on their path to practical application. First, at the bulk structure level, the kinetic control of the self-assembly process is difficult, easily leading to uneven phase separation and discontinuous channels, resulting in fluctuations in ionic conductivity. Furthermore, during solution casting, solvent evaporation often causes a sharp decrease in free volume, resulting in microstructural collapse, disrupting the original ordered arrangement, severely affecting the connectivity of ion transport pathways, hindering the formation of a uniform and dense interface layer, and increasing the risk of localized current concentration. Second, at the electrode-electrolyte interface level, the high interfacial impedance caused by solid-solid contact is particularly prominent; unoptimized interfacial contact impedance can reach the KΩ level, severely impeding lithium-ion cross-interface migration. Adding to the complexity, the significant difference in lithium-ion concentration between the electrolyte and the electrode easily leads to a space charge layer effect, resulting in a lithium-ion concentration gradient exceeding three orders of magnitude in the interfacial region, further exacerbating polarization and affecting battery cycle stability and rate performance.

[0006] Therefore, there is an urgent need in this field to develop a novel polymer electrolyte structure and its preparation method that can fundamentally optimize the lithium-ion transport path, effectively reduce interfacial impedance, and simultaneously improve the bulk ionic conductivity and interfacial stability of the electrolyte. At the molecular structure design level, precise control of the topology is required to ensure the repeatability of self-assembly behavior and structural uniformity. Simultaneously, the introduction of dynamic covalent bonds can be considered to enable self-driving capabilities, thereby improving the long-term stability of the material. Regarding the preparation process, in-situ polymerization technology is considered an effective way to solve interfacial problems. By directly initiating monomer polymerization on the electrode surface, a tight molecular-level bond between the electrolyte and the electrode can be achieved, significantly reducing interfacial impedance. Summary of the Invention

[0007] This invention addresses the problems of poor solid-solid interface contact, high interface impedance, discontinuous ion channels, and difficulty in achieving both high ionic conductivity and mechanical rigidity caused by the non-in-situ preparation of polymer electrolytes in the prior art. It proposes a block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design, as well as its preparation method, and applies it to solid-state batteries. This scheme designs an ABC-type triblock copolymer structure at the molecular level. Block A is a monomer of an olefin derivative below C12 containing at least one benzene ring substituent to provide high-strength skeletal support. Block B is a crosslinking agent containing multiple acrylate groups to enhance dendrite suppression and establish a three-dimensional skeleton. Block C introduces a dynamic self-healing unit with ion coupling to endow the material with self-healing properties. Furthermore, this scheme constructs a three-layer gradient rigid system at the structural level. A rigid polymer layer is set on the negative electrode side, a neutral polymer layer is set between the negative and positive electrode sides as a transition layer, and a flexible polymer layer is set on the positive electrode side. The gradient transition from rigid to flexible is achieved through covalent bonding. This achieves systematic innovation from multiple perspectives, including molecular structure design, film formation process control, and macroscopic structural layout, effectively solving the problem of comprehensive performance synergistic optimization in existing technologies.

[0008] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design. The block copolymer solid electrolyte comprises polymer layers with gradient rigidity along the thickness direction. Each polymer layer has an ABC-type block copolymer, wherein block A is a monomer of an olefin derivative with at least one benzene ring substituent group below C12, block B is a crosslinking agent, and block C is an ion-coupled monomer. The gradient rigidity between the polymer layers is adjusted by changing the ratio of each block in the ABC-type block copolymer. The ion-coupled monomer is selected from compounds of formula 1 or formula 2, wherein R1 and R2 are each independently selected from substituted or unsubstituted C2-C4 alkyl chains, and when R1 or R2 is substituted, the substituent group is selected from one or more of C1-C3 alkyl, C1-C3 alkoxy, carboxyl, and phosphoryl groups, wherein M - X is selected from one of the lithium salt anionic groups. - R9 is selected from one of the functional groups of anionic ligands, and R9 is selected from one of the alkyl groups of C0 to C3. ; The crosslinking agent is selected from one of the polyol acrylate compounds.

[0009] When R9 is a C0 alkyl group, the vinyl group is directly connected to the imidazole group.

[0010] This invention innovatively provides a block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design. Addressing the technical problems of existing polymer electrolytes, such as the difficulty in balancing ionic conductivity and mechanical strength, poor solid-solid interface contact leading to excessively high interfacial impedance, and performance degradation of the electrolyte membrane due to structural defects or damage during long-term cycling, this invention, through molecular structure design and material composition optimization, designs an ABC-type block copolymer structure at the molecular level, composed of ion-coupled monomers, olefin derivative monomers below C12 containing at least one benzene ring substituent, and a crosslinking agent. This provides a block copolymer solid electrolyte with high ionic conductivity, excellent mechanical properties, and dynamic self-healing function, aiming to fundamentally solve the core problems of poor interfacial stability and low ionic conductivity faced by traditional polymer electrolyte systems. The monomers, containing at least one benzene ring substituent, are C12- or lower olefin derivatives used as raw materials for block A. On one hand, the alkenyl groups provide crosslinking sites for thermal polymerization; on the other hand, benzene provides high-strength skeletal support and antioxidant capacity. The crosslinking agent, used as raw material for block B, possesses a polyol acrylate structure with excellent dendrite suppression, thermal stability, and safety performance. It can also connect blocks A and C. Ion-coupled monomers, used as raw materials for block C, introduce ion-coupled dynamic self-healing functional units, endowing the material with self-healing properties. The design of a polymer layer with gradient rigidity along the thickness direction allows for physical blocking of lithium dendrite growth near the negative electrode by adjusting the ratio of each block; while the side near the positive electrode exhibits a certain degree of flexibility, ensuring good interface adhesion and encapsulation adaptability. This gradient rigidity design avoids the problem of weak interlayer connections, thus obtaining a gradient structure from rigid to flexible. This multifunctional integrated molecular architecture and gradient rigidity design not only facilitate the formation of ordered nanochannels but also enable local reconstruction upon damage, synergistically solving problems such as low ionic conductivity, low mechanical strength, and low self-healing ability in existing technologies.

[0011] Specifically, the ion-coupled structure in the ion-coupled monomer used in this invention exhibits a unique synergistic effect during polymerization. Compared to using a mixture of quaternary ammonium ion sulfonates and lithium salts as raw materials for preparing block copolymer solid electrolytes, the ion-coupled monomer used in this invention is a product of a specific quaternary ammonium salt and lithium salt compounded in water. In this process, the larger organic anions in the lithium salt can partially replace the anionic sites in the quaternary ammonium salt through ion exchange, forming a coexisting complex ion cluster structure. The overall polarity of this structure is effectively regulated. At this point, the large-sized organic anions can bridge the polarity difference between the ion-coupled monomer and the weakly polar aromatic hydrocarbon. Therefore, the ion-coupled monomer can directly achieve uniform mixing at the molecular level with olefin derivative monomers containing at least one benzene ring substituent and acrylate crosslinking agents. This avoids the problems of reduced polymerization efficiency and reduced purity of polymerization products faced when directly using a mixture of quaternary ammonium ion sulfonates and lithium salts as raw materials for preparing block copolymer solid electrolytes. At the same time, the anionic ligand functional groups in the ion-coupled monomer and the organic anions (such as TFSI) introduced by the lithium salt compounding... - Lithium ions possess strong polarity and delocalized charge, while polyol acrylate crosslinking agents contain numerous polar groups such as ether oxygen bonds (COC) and ester groups (C=O). A strong ion-dipole interaction exists between the two. This interaction serves multiple functions during polymerization: First, it guides the uniform distribution of ion-coupled monomers around the network framework constructed by the crosslinking agent, preventing local aggregation of ion groups and achieving uniform anchoring of ion transport sites within the polymer's three-dimensional network. Second, the ion-dipole interaction can, to some extent, restrict the free movement of crosslinking agent molecules, controlling the polymerization rate within a certain range and avoiding network inhomogeneity or localized stress concentration caused by excessively rapid crosslinking reactions. Finally, the electrostatic repulsion between uniformly distributed ion groups helps to expand the crosslinked network, increasing the free volume within the network and providing more spacious channels for the rapid migration of lithium ions, thereby mitigating the negative impact of increased crosslinking density on ion transport. This molecular-level compatibility lays the fundamental foundation for the subsequent formation of a regular, continuous, and interconnected ion transport network.

[0012] Specifically, the ion-coupled monomer simultaneously contains quaternary ammonium cation groups and anionic ligand functional groups (such as sulfonic acid anions or carboxylic acid anions), forming an intramolecular ion-pair structure. This unique "ion dipole" design has multiple functions: on the one hand, groups such as lithium sulfonate or lithium carboxylic acid salts can directly provide a sufficient source of lithium ions, and the interaction between their anionic portions and lithium ions is moderate, which is conducive to the dissociation and migration of lithium ions; on the other hand, the quaternary ammonium cation and anion M -The electrostatic interactions between them can form dynamic and reversible ionic cross-linking points, constructing a physical cross-linking network in the polymer matrix. When the material is mechanically damaged, these ion pairs can recombine to achieve self-repair of the network structure, giving the electrolyte membrane a "self-healing" ability and significantly improving the long-term cycle stability of the battery.

[0013] The ion-coupled monomer contains unsaturated double bonds at its ends, allowing it to participate in subsequent free radical polymerization reactions. Through copolymerization with olefin derivative monomers (C12 and below) containing at least one benzene ring substituent and a crosslinking agent, a three-dimensional crosslinked network structure is formed. This structural design achieves functional complementarity and synergy: ionic conduction is provided collaboratively by the lithium salt groups in the ion-coupled monomer and the flexible units in the polymer segments; mechanical support is provided by the rigid aromatic segments formed after polymerization of the olefin derivative monomers (C12 and below) containing at least one benzene ring substituent; and dynamic self-healing is provided by the anionic ligand functional groups in the ion-coupled monomer. These three components are covalently linked within the same polymer network, avoiding problems such as uneven phase separation and interface defects caused by physical blending in traditional composite systems.

[0014] In summary, this invention employs ion-coupled monomers, achieving comprehensive optimization in terms of monomer solubility, polymerization behavior, network structure, interfacial interactions, and self-healing capabilities. Compared to quaternary ammonium salts without ion-coupled structures, the ion-coupled monomers provided by this invention can synergistically copolymerize with C12- or lower olefin derivative monomers containing at least one benzene ring substituent and polyol acrylate compounds as crosslinking agents. This constructs a three-dimensional polymer electrolyte network with high ion conductivity, excellent mechanical strength, stable and reliable interfaces, and self-healing capabilities. Furthermore, by adjusting the proportion of each block, a gradient rigidity polymer layer is constructed to meet the structural requirements of solid-state batteries, providing a key molecular engineering solution for overcoming the performance bottlenecks of solid-state batteries.

[0015] As a further embodiment, the polymer layer with gradient rigidity includes a rigid polymer layer located on the negative electrode side, a flexible polymer layer located on the positive electrode side, and a neutral polymer layer located within the pores of the positive and negative electrode separator membrane.

[0016] As a further embodiment, the C12- or lower olefin derivative monomer containing at least one benzene ring substituent is selected from compounds of Formula 3. , R3, R4, and R5 are each independently selected from one or more of the following: hydrogen atom, C1-C2 alkyl group, C1-C2 alkoxy group, amino group, hydroxyl group, cyano group, carboxyl group, acyl group, and halogen atom. R3 can be attached to any position on the benzene ring except for the carbon atom attached to the alkenyl chain; n is an integer from 0 to 4.

[0017] As an example, when R3 is a hydrogen atom, R5 is a hydrogen atom, and n=0, the olefin derivative monomer with at least one benzene ring substituent group having a C12 or less structure is styrene.

[0018] As a further embodiment, the anionic ligand functional group X - It is selected from one of the functional groups of oxyanionic ligands.

[0019] As a further preferred embodiment, the oxyanionic ligand functional group includes one of carboxylate ions, sulfonate ions, phosphonate ions, and sulfate ions.

[0020] As a further preferred embodiment, the anionic ligand functional group X - It is a sulfonate ion.

[0021] As a further embodiment, R1 and R2 in the ion-coupled monomer are each independently selected from one of the C2-C3 straight-chain alkyl groups.

[0022] This invention further optimizes the groups R1 and R2 in the ion-coupled monomer. The shorter straight-chain alkyl group effectively reduces steric hindrance of the molecular chain, enhancing the ion-pair dissociation ability between the quaternary ammonium cation and the oxyanion, thereby promoting rapid lithium-ion migration. Simultaneously, the short-chain alkyl structure helps improve the monomer's reactivity during polymerization, making the polymerization reaction easier to control. The resulting polymer chain segments are more regularly arranged, which is beneficial for constructing continuous, low-torsion ion conduction channels. Furthermore, the smaller alkyl volume reduces the adverse effects on the flexibility of the polymer backbone, avoiding restricted chain movement due to steric hindrance. This maintains high ion mobility while ensuring mechanical strength, further improving the room-temperature ionic conductivity and interfacial stability of the electrolyte.

[0023] As a further option, the polyol acrylate is selected from one or more of polyol triacrylate and polyol tetraacrylate.

[0024] As a further preferred embodiment, the ion-coupled monomer is selected from compounds of formula 1, wherein R1 and R2 are each independently selected from an unsubstituted C2-C3 straight-chain alkyl group, and M... - The crosslinking agent is selected from one of the lithium salt anionic groups, wherein the anionic ligand functional group is a sulfonate ion, the crosslinking agent is selected from one of the polyol triacrylates, and the olefin derivative monomer containing at least one benzene ring substituent is selected from one of the compounds with the structure of Formula 2, wherein R3 is a hydrogen atom, n=0, and R5 is selected from one or more of hydrogen atoms and C1~C2 alkyl groups.

[0025] This invention further selects ion-coupled monomers with sulfonate anions, which exhibit stronger electron-withdrawing inductive effects and higher charge delocalization compared to carboxylate anions. The sulfur atom in the sulfonate group is in a high valence state, and its negative charge is effectively dispersed through the resonance structure of three oxygen atoms, resulting in a lower binding energy between lithium ions and anions in the lithium sulfonate salt, making lithium ions more prone to dissociation and migration. This characteristic is crucial for improving the ionic conductivity of the polymer electrolyte; the weaker the interaction between lithium ions and anions, the higher the concentration of free lithium ions and the faster the ion migration rate. Simultaneously, this invention limits R1 and R2 to unsubstituted C2-C3 straight-chain alkyl groups (such as ethyl or propyl). This choice is based on a balance between the dynamic reversibility of the ion-coupled structure and the steric hindrance effect. Shorter straight-chain alkyl groups ensure that the quaternary ammonium cation has a higher charge density and stronger ion pairing ability, which is beneficial for constructing a stable dynamic physical cross-linking network. At the same time, unsubstituted alkyl groups avoid side reactions or compatibility problems that may arise from additional functional groups. If the alkyl chain is too long (exceeding C4) or has branches, it will increase the steric hindrance of the quaternary ammonium cation, weaken its electrostatic interaction with the anion, and lead to a decrease in the dynamic reversibility of the ion pair and a reduction in self-healing ability. At the same time, an excessively long alkyl chain may also increase the flexibility of the polymer chain segment, sacrificing mechanical strength. If there is no alkyl chain or an excessively short alkyl chain is selected, although the ion pair interaction is the strongest, the excessive rigidity may affect the chain segment movement and ion conduction. C2-C3 straight-chain alkyl chains achieve a further balance between ion pair strength, chain segment movement ability, and steric hindrance. Meanwhile, after optimization, R3 and R5 in olefin derivative monomers with at least one benzene ring substituent group below C12 have high glass transition temperature and high rigidity after polymerization, which can provide excellent mechanical support for the polymer electrolyte and effectively inhibit the growth of lithium dendrites. Meanwhile, the rigid framework of aromatic rings exhibits good thermal and chemical stability, maintaining structural integrity within the battery operating temperature range and resisting chain segment relaxation or creep. Electron-rich aromatic rings in C12- and below olefin derivative monomers containing at least one benzene ring substituent exist in cation-π interactions with quaternary ammonium cations in ion-coupled monomers. These interactions can induce monomer pre-assembly before polymerization. Triacrylate crosslinking agents can construct moderately crosslinked three-dimensional network structures during polymerization. Compared to diacrylate crosslinking agents, triacrylates form more stable and complete crosslinked networks, providing higher mechanical strength and structural stability. Compared to tetraacrylates or higher-functionality crosslinking agents, triacrylates have a moderate crosslinking density, avoiding problems such as excessive network rigidity, increased brittleness, and restricted ionic chain movement caused by over-crosslinking. This moderately crosslinked network structure achieves a further balance between mechanical strength and ion conductivity efficiency.

[0026] In summary, this invention utilizes a preferred quaternary ammonium lithium ion sulfonate salt (R1 and R2 are C2-C3 straight-chain alkyl groups), an olefin derivative monomer containing at least one benzene ring substituent (R3 is a hydrogen atom, n=0, and R5 is selected from hydrogen atoms and C1-C2 alkyl groups), and a polyol triacrylate crosslinking agent as block components. This achieves further matching and synergy in molecular structure and performance between block C, which dominates ion conduction, block A, which dominates mechanical support, and block B, which dominates network crosslinking. This preferred scheme can further leverage the synergistic effects of various intermolecular interactions such as cation-π, ion-dipole, and hydrogen bonds between the ion-coupled structure and other components in the system, ultimately constructing a three-dimensional polymer electrolyte network with high ionic conductivity, excellent mechanical strength, good interfacial stability, and dynamic self-healing capabilities. This provides an optimized material solution for the development of high-performance solid-state lithium batteries.

[0027] As a further embodiment, the C12 or lower olefin derivative monomer containing at least one benzene ring substituent is selected from one or more of vinylbenzene, 1,3-diisopropenylbenzene, 3-(trifluoromethyl)styrene, and 1-fluoro-4-[1-(trifluoromethyl)vinyl]benzene.

[0028] As a further embodiment, the polyol acrylate compound includes one or more of the following: trimethylolpropane ethoxylate triacrylate, propoxylated trimethylolpropane triacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pent- / hexyl-acrylate, and glycerol propoxy acid (1PO / OH) triacrylate.

[0029] As a further embodiment, the tensile strength of the rigid polymer layer is 300~600 Kgf / cm. 2 The tensile strength of the neutral polymer layer is 100-300 Kgf / cm. 2 The tensile strength of the flexible polymer layer is 30~100 Kgf / cm. 2 .

[0030] As a further preferred embodiment, the tensile strength of the rigid polymer layer is 400-500 Kgf / cm. 2 The tensile strength of the neutral polymer layer is 200-300 Kgf / cm. 2 The tensile strength of the flexible polymer layer is 50-80 kgf / cm. 2 .

[0031] As a further embodiment, the ionic conductivity of the rigid polymer layer is ≥1.8×10⁻⁶. -4 S cm -1 The ionic conductivity of the neutral polymer layer is ≥2.3 ×10⁻⁶.-4 S cm -1 The ionic conductivity of the flexible polymer layer is ≥2.7 ×10⁻⁶. -4 S cm -1 .

[0032] Secondly, the present invention provides a solvent-free polymer precursor for preparing the block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design. The solvent-free polymer precursor includes an ion-coupled monomer, an olefin derivative monomer containing at least one benzene ring substituent, a crosslinking agent, an initiator, and a second lithium salt.

[0033] The polymer precursor provided by this invention does not use a solvent. In this case, on the one hand, solvent residue caused by incomplete solvent evaporation is avoided. On the other hand, the ion-coupled monomer used in this invention can act as a solvent in the precursor, achieving uniform dispersion of the precursor components. At the same time, in the absence of solvent and solvent residue, the above material can achieve more efficient polymerization, avoid the generation of by-products, improve the purity and efficiency of polymerization, and thus improve the performance of the battery.

[0034] As a further option, by changing the proportion of each component in the solvent-free polymer precursor, a solvent-free rigid polymer precursor for preparing the rigid polymer layer, a solvent-free neutral polymer precursor for preparing the neutral polymer layer, and a solvent-free flexible polymer precursor for preparing the flexible polymer layer can be obtained.

[0035] As a further embodiment, in the solvent-free rigid polymer precursor, the molar ratio of the C12- or lower olefin derivative monomer containing at least one benzene ring substituent to the ion-coupled monomer is 1:(0.8~1.1), the crosslinking agent accounts for 7~9 wt% of the total mass of the ion-coupled monomer and the C12- or lower olefin derivative monomer containing at least one benzene ring substituent, and the initiator accounts for 2.5~3.5 wt% of the total mass of the ion-coupled monomer, the crosslinking agent, and the C12- or lower olefin derivative monomer containing at least one benzene ring substituent. In the solvent-free neutral polymer precursor, the molar ratio of the C12- or lower olefin derivative monomer containing at least one benzene ring substituent to the ion-coupled monomer is 1:(1.3~1.7), the crosslinking agent accounts for 3~5 wt% of the total mass of the ion-coupled monomer and the C12- or lower olefin derivative monomer containing at least one benzene ring substituent, and the initiator accounts for 1~3 wt% of the total mass of the ion-coupled monomer, the crosslinking agent, and the C12- or lower olefin derivative monomer containing at least one benzene ring substituent. In the solvent-free flexible polymer precursor, the molar ratio of the C12- or lower olefin derivative monomer containing at least one benzene ring substituent to the ion-coupled monomer is 1:(2~4), the crosslinking agent accounts for 1~3 wt% of the total mass of the ion-coupled monomer and the C12- or lower olefin derivative monomer containing at least one benzene ring substituent, and the initiator accounts for 0.5~1.2 wt% of the total mass of the ion-coupled monomer, the crosslinking agent, and the C12- or lower olefin derivative monomer containing at least one benzene ring substituent.

[0036] This invention, based on the spatial arrangement of electrode structures and the operating principle of batteries, utilizes specific proportions of components in polymer precursors to form solvent-free polymer precursors with varying degrees of rigidity after polymerization, which can be used for the fabrication of electrodes or solid-state batteries. This allows for the physical inhibition of lithium dendrite growth near the negative electrode, while the side near the positive electrode exhibits a degree of flexibility, ensuring good interface adhesion and encapsulation adaptability. The gradient rigidity design avoids the problem of weak interfacial connections, thus achieving a gradient structure from rigid to flexible. This multifunctional integrated molecular architecture and gradient rigidity design not only facilitates the formation of ordered nanochannels but also enables local reconstruction upon damage, solving problems such as low ionic conductivity, low mechanical strength, and low self-healing ability in existing technologies. Specifically, a solvent-free rigid polymer precursor is used, which is composed of a high mass ratio of olefin derivative monomers with at least one benzene ring substituent group below C12, and uses a high amount of crosslinking agent and initiator, and a low molar ratio of ion-coupled monomers. This allows a rigid polymer layer to be formed near the lithium anode to physically block lithium dendrite growth. Meanwhile, the flexible polymer layer formed by the polymerization of the solvent-free flexible polymer precursor has a certain degree of flexibility near the cathode, ensuring good interface adhesion and encapsulation adaptability. The three-layer structure avoids the weak interface connection problem caused by traditional multilayer stacking through covalent bonds, thereby obtaining a gradient structure from high rigidity (rigid) to low rigidity (flexible). Specifically, this invention achieves targeted control over the crosslinking density and mechanical properties of the final polymer electrolyte by precisely controlling the ratio of ion-coupled monomers, C12- or lower olefin derivative monomers containing at least one benzene ring substituent, and crosslinking agents in a solvent-free polymer precursor. Increasing the amount of C12- or lower olefin derivative monomers containing at least one benzene ring substituent promotes the formation of rigid blocks, enhancing the material's rigidity; increasing the amount of crosslinking agent increases the crosslinking density of the network, further strengthening mechanical strength; while the content of ion-coupled monomers directly affects the density of lithium-ion conduction sites, the degree of crosslinking polymerization, and self-healing ability. Through the synergistic control of these three components, tensile strength can be improved while maintaining high ionic conductivity, effectively overcoming the performance bottlenecks of traditional polymer electrolytes.

[0037] As a further preferred embodiment, the molar ratio of the C12- or lower olefin derivative monomer containing at least one benzene ring substituent to the ion-coupled monomer in the solvent-free rigid polymer precursor is 1:(0.9~1.1), the crosslinking agent accounts for 7.5~8.5 wt% of the total mass of the ion-coupled monomer and the C12- or lower olefin derivative monomer containing at least one benzene ring substituent, and the initiator accounts for 2.7~3.2 wt% of the total mass of the ion-coupled monomer, the crosslinking agent, and the C12- or lower olefin derivative monomer containing at least one benzene ring substituent. The solvent-free neutral polymer precursor contains a C12 or less olefin derivative monomer with at least one benzene ring substituent group in a molar ratio of 1:(1.4~1.6). The crosslinking agent accounts for 3.5~4.5 wt% of the total mass of the ion-coupled monomer and the C12 or less olefin derivative monomer with at least one benzene ring substituent group. The initiator accounts for 1.5~2.5 wt% of the total mass of the ion-coupled monomer, the crosslinking agent, and the C12 or less olefin derivative monomer with at least one benzene ring substituent group. The solvent-free flexible polymer precursor contains a C12 or less olefin derivative monomer with at least one benzene ring substituent group in a molar ratio of 1:(2.5~3.5) to an ion-coupled monomer. The crosslinking agent accounts for 1.5~2.5 wt% of the total mass of the ion-coupled monomer and the C12 or less olefin derivative monomer with at least one benzene ring substituent group. The initiator accounts for 0.9~1.1 wt% of the total mass of the ion-coupled monomer, the crosslinking agent, and the C12 or less olefin derivative monomer with at least one benzene ring substituent group.

[0038] As a further preferred embodiment, the proportion of the second lithium salt in the solvent-free rigid polymer precursor, solvent-free neutral polymer precursor, and solvent-free flexible polymer precursor is 10~30wt% of the ion-coupled monomer in the solvent-free rigid polymer precursor, solvent-free neutral polymer precursor, and solvent-free flexible polymer precursor, respectively.

[0039] Specifically, as an example, the proportion of the second lithium salt in the solvent-free rigid polymer precursor is 10 to 30 wt% of the ion-coupled monomer in the solvent-free rigid polymer precursor.

[0040] The present invention further optimizes the amount of the second lithium salt in the precursor, thereby further optimizing ion transport based on the above.

[0041] As a further option, the second lithium salt is selected from one or more of lithium sulfonamide, lithium phosphate, lithium borate, and lithium oxalate borate.

[0042] As a further embodiment, the lithium phosphate salt includes one or more of lithium hexafluorophosphate, lithium tetrafluorophosphate, lithium difluorophosphate, and lithium trifluoromethylphosphate.

[0043] As a further embodiment, the lithium borate salt includes one or more of lithium tetrafluoroborate and lithium trifluoromethyl trifluoroborate.

[0044] As a further embodiment, the lithium sulfonylimide salt includes one or more of lithium bis(trifluoromethanesulfonylimide) and lithium bis(fluorosulfonylimide).

[0045] As a further embodiment, the lithium oxalate borate salt is selected from one or more of lithium dioxalate borate and lithium difluorooxalate borate.

[0046] As a further preferred embodiment, the second lithium salt is selected from one or more lithium sulfonate salts or lithium sulfonamide salts.

[0047] The present invention further preferably uses lithium sulfonate or lithium sulfonyl imide as the second lithium salt. These lithium salts exhibit unique structural matching and functional synergy with the ion-coupled monomers, maximizing the design advantages of the ion-coupled structure and bringing multifaceted performance improvements to the polymer electrolyte. Lithium sulfonate salts, such as lithium trifluoromethanesulfonate, or lithium sulfonyl imide salts, such as lithium bis(trifluoromethanesulfonyl imide) and lithium bis(fluorosulfonyl imide), share the common characteristic of having a large molecular size and a highly delocalized negative charge structure in their anionic portion. This structural feature allows them to form a more stable ion cluster structure when interacting with the quaternary ammonium cation in the ion-coupled monomer. Simultaneously, the delocalized charge of the large-sized anion effectively shields the electrostatic attraction between the quaternary ammonium cation and the sulfonic acid / carboxylic acid anion, moderately regulating the formation and dissociation balance of ion pairs. This ensures that the dynamic physical cross-linking network possesses sufficient stability to maintain structural integrity while maintaining appropriate dynamic reversibility to achieve self-healing functionality.

[0048] Thirdly, the present invention provides a method for preparing the polymer precursor, comprising the following steps: S1: The compound of formula 4 or formula 5 and the compound of formula 6 are mixed in a solvent at a molar ratio of 1:(0.9~1.1), reacted at 45~55℃ for 40~60h, and then allowed to stand at room temperature for 10~14h. After washing and drying, the mixture is mixed with the first lithium salt in deionized water at a molar ratio of 1:(0.9~1.1), and then washed and dried to obtain the ion-coupled monomer. In Formula 4, R6 is selected from one of substituted or unsubstituted C2-C4 alkyl chains. When R6 is substituted, the substituent group is selected from one or more of C1-C3 alkyl, C1-C3 alkoxy, carboxyl, and phosphoryl groups. In Formula 6, X is selected from one of oxyacid groups, which is X in the block copolymer solid electrolyte.- The oxyacid group corresponding to the oxyacid anion is R7, which is selected from a substituted or unsubstituted C1-C3 alkyl chain. When R7 is substituted, the substituent group is selected from one of C1-C3 alkyl, C1-C3 alkoxy, carboxyl, and phosphoryl groups; R8 is selected from one of a hydrogen atom, a C1-C3 alkyl, a C1-C3 alkoxy, carboxyl, and phosphoryl groups. 10 Selected from one of the C0-C3 alkyl groups;

[0049] , S2: Mix the ion-coupled monomer, the second lithium salt, the olefin derivative monomer containing at least one benzene ring substituent group (C12 or less), the crosslinking agent, and the initiator uniformly according to the target mass ratio to prepare solvent-free rigid polymer precursor, solvent-free neutral polymer precursor, and solvent-free flexible polymer precursor, respectively.

[0050] This invention innovatively employs a step-by-step precursor preparation method. In the first step, an ion-coupled monomer is prepared. The ion-coupled structure in this monomer exhibits a unique synergistic effect during polymerization. Compared to using a mixture of quaternary ammonium ion sulfonate and a second lithium salt as the raw material for preparing block copolymer solid electrolytes, the ion-coupled monomer used in this invention is a product of a specific quaternary ammonium acrylate salt and a first lithium salt. In this process, the larger organic anions in the lithium salt can partially replace the anion sites in the quaternary ammonium salt through ion exchange, forming a coexisting complex ion cluster structure. The overall polarity of this structure is effectively regulated. At this point, the large-sized organic anions can bridge the polarity difference between the ion-coupled monomer and the weakly polar aromatic hydrocarbon. Therefore, the ion-coupled monomer can be directly and uniformly mixed at the molecular level with olefin derivative monomers containing at least one benzene ring substituent and acrylate crosslinking agents. This invention avoids the problems of reduced polymerization efficiency and lower purity of polymerization products encountered when using a mixture of quaternary ammonium ion sulfonates and lithium salts as raw materials for preparing block copolymer solid electrolytes. Furthermore, it avoids the need for solvents to dissolve and form a complex system in subsequent precursor preparation, thus avoiding residue problems during subsequent solvent removal. In the step-by-step preparation method, water is used as the reaction medium in step S1 to obtain the target ion-coupled monomer, and the product, after washing and drying, is directly a liquid that can be used to dissolve lithium salts and prepare solutions. This avoids the problems associated with using quaternary ammonium ions in the prior art. When oxyanionic salts (such as quaternary ammonium ion sulfonates), lithium salts, and crosslinking agents are blended as precursors, solvents such as DME and acetonitrile are required to provide a reaction medium for the formation of ion-coupled monomers. However, DME and other solvents still leave residues under evaporation and drying conditions. This avoids the problems of reduced conductivity and increased side reactions in the prepared polymer electrolyte caused by these residues. It also avoids the use of solvents in S2, reduces operational complexity, decreases the number of solvent removal steps, avoids the impact of solvent residues on material properties, and avoids environmental pollution caused by solvent removal. Furthermore, in this invention, when the precursor is solvent-free, the ion-coupled monomer, the C12- or lower olefin derivative monomer containing at least one benzene ring substituent, and the crosslinking agent can achieve more efficient generation and polymerization of the ion-coupled monomer compared to when solvent residues are present, thus improving product formation efficiency and purity. The ion-coupled monomer synthesis process selected in this invention is simple, the raw materials are readily available, the reaction conditions are mild, and it is suitable for large-scale production. The preparation process first involves the ring-opening reaction of dimethylaminoalkyl acrylate (as shown in Formula 3) with an epoxy lactone to generate a quaternary ammonium ionic sulfonate or a quaternary ammonium ionic carboxylate, which is then subjected to an ion exchange reaction with a lithium salt to obtain the target product. This synthetic route avoids complex protection and deprotection steps, offers high yields, is easy to purify, and has promising prospects for industrial applications.

[0051] As a further option, the first lithium salt in S1 and the second lithium salt in S2 can be the same or different lithium salts.

[0052] As a further preferred embodiment, the first lithium salt in S1 and the second lithium salt in S2 are the same lithium salt.

[0053] As an example, when R6 in Formula 4 is a C2 alkyl group, the compound of Formula 4 is dimethylaminoethyl acrylate.

[0054] As an example, when R7 in Formula 6 is a C2 alkyl group, R8 is a hydrogen atom, and X is a sulfonic acid group, the compound of Formula 6 is 1,3-propanesulfonic acid lactone.

[0055] As an example, when X in the ion-coupled monomer - When X is a sulfonate ion, X is a sulfonic acid group (-SO3-).

[0056] Fourthly, the present invention also provides a solidified electrode comprising the block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design, the solidified electrode comprising a positive solidified electrode and a negative solidified electrode, the positive solidified electrode comprising a positive electrode impregnated with a flexible polymer layer, and the negative solidified electrode comprising a negative electrode impregnated with a rigid polymer layer.

[0057] As a further embodiment, the positive electrode sheet contains a positive active material, and the negative electrode sheet contains a negative active material.

[0058] Fifthly, the present invention also provides a method for preparing the solidified electrode, wherein the solidified electrode is obtained by thermosetting an electrode coated with a polymer precursor at 60-70 °C for 13-18 h.

[0059] As a further embodiment, the solvent-free rigid polymer precursor is coated onto the surface of the negative electrode sheet in an amount of 10-30 μL and a thickness of 30-50 μm. The negative electrode sheet is then thermo-cured at 60-70 °C for 13-18 h to obtain the solidified negative electrode sheet, wherein the surface of the solidified negative electrode sheet has a high-rigidity polymer.

[0060] As a further embodiment, the solvent-free low-rigidity polymer precursor is coated onto the surface of the positive electrode current collector with a coating amount of 5-20 μL and a coating thickness of 5-15 μm. After negative pressure treatment for 3-5 h, the positive electrode solidification sheet is obtained by thermosetting at 60-70 °C for 13-18 h. The surface of the positive electrode solidification sheet has a low-rigidity polymer.

[0061] In a sixth aspect, the present invention also provides an all-solid-state battery, the all-solid-state battery comprising the block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design.

[0062] As a further embodiment, the all-solid-state battery includes a positive solid-state electrode, a negative solid-state electrode, and a separator impregnated with a neutral polymer layer.

[0063] As a further embodiment, the flexible polymer layer is polymerized on the positive solid-state electrode, and the rigid polymer layer is polymerized on the negative solid-state electrode.

[0064] The all-solid-state battery prepared by this invention consists of a solid negative electrode with a rigid polymer layer formed by polymerizing a solvent-free rigid polymer precursor on an electrode containing a negative electrode active material, a solid positive electrode with a flexible polymer layer formed by polymerizing a solvent-free flexible polymer precursor on a positive electrode containing a positive electrode active material, and a separator with a neutral polymer layer formed by polymerizing a solvent-free rigid polymer precursor between the solid positive electrode and the solid negative electrode. This achieves efficient interlayer ion transport and structural support.

[0065] In a seventh aspect, the present invention also provides a method for preparing an all-solid-state battery, comprising the following steps: sequentially assembling a positive solid-state electrode, a separator, and a negative solid-state electrode into an all-solid-state battery, adding a solvent-free medium-rigid polymer precursor at the positive electrode and separator and at the negative electrode and separator, and obtaining the all-solid-state battery after thermal curing at 60~70 °C for 13~18 h.

[0066] The features and beneficial effects of this invention are as follows: 1. Construction of an integrated gradient rigid structure based on in-situ solidification process: This transforms "in-situ solidification" from a simple molding process into a means of actively constructing gradient rigid structures. It achieves a continuous and gradual distribution of crosslinking density, chain segment rigidity, or component distribution from the lithium metal anode side to the cathode side. This integrated, gradient rigid structure forms a high-rigidity layer on the anode side to physically suppress lithium dendrites, and a low-rigidity flexible layer on the cathode side to optimize solid-solid interface contact, potentially solving the challenge of balancing battery interface stability and ion transport efficiency.

[0067] 2. Microphase separation and channel optimization of block copolymers induced by in-situ polymerization: This invention combines "in-situ solidification" with "block copolymerization" molecular design. During the polymerization reaction, by controlling the synergistic effect of monomer diffusion, reaction rate, and phase separation kinetics, lithiophilic and lithiophore blocks are induced to spontaneously assemble and form long-range ordered, three-dimensionally interconnected ordered nanostructures. This process overcomes the structural collapse and channel discontinuity defects caused by solvent evaporation in traditional solution casting methods, ensuring maximum connectivity and low tortuosity of lithium-ion transport channels, thereby maintaining ideal ionic conductivity while improving mechanical strength.

[0068] 3. Interface optimization: This patent combines semi-in-situ and in-situ curing. The in-situ curing technology directly polymerizes the liquid precursor into a solid state inside the battery, achieving molecular-level wetting and integral molding with the electrode. Compared with the "film formation before assembly" of the simple semi-in-situ technology, it can form a solid-solid interface with lower interfacial impedance, more uniform contact and higher stability from the source. Attached Figure Description

[0069] To more clearly illustrate the technical solutions in the embodiments of the present invention, 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.

[0070] Figure 1 The 1H NMR characterization results are for the ion-coupled monomer prepared in Example 1.

[0071] Figure 2 The thermogravimetric loss diagram is shown in Example 1.

[0072] Figure 3 The cycling performance of Example 1 in the first 50 cycles at a 0.1C rate is shown. Detailed Implementation

[0073] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below, and embodiments of the present invention will be provided, but this does not limit the scope of the present invention.

[0074] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0075] The chemical raw materials used in the following examples and comparative examples are all prior art and commercially available. The experimental apparatus and testing equipment used in the following examples and comparative examples are all conventional equipment in the art, and there are no special requirements or limitations.

[0076] As a specific example of the implementation of this invention, detailed cases are provided below: Example 1: Step 1: The desired ion-coupled monomer was synthesized via the ring-opening reaction of dimethylaminoethyl acrylate and 1,3-propanesulfonic acid lactone, as described in Formula 7. In a round-bottom flask, 5 g of dimethylaminoethyl acrylate, 4.7 g of 1,3-propanesulfonic acid lactone (molar ratio of dimethylaminoethyl acrylate to 1,3-propanesulfonic acid lactone was 1:1.1), and 50 mL of acetonitrile were added. After stirring, the mixture was heated to 50°C and reacted for 48 h to obtain a large amount of white precipitate. The precipitate was then allowed to stand at room temperature for 12 h, during which the product continued to increase. After standing, the product was filtered, repeatedly washed, and dried to obtain the quaternary ammonium ion sulfonate: 3-((2-(acryloyloxy)ethyl)dimethylammonium)propane-1-sulfonic acid lactone.

[0077] Step 2: As per Formula 8, the obtained quaternary ammonium ionic sulfonate 3-((2-(acryloyloxy)ethyl)dimethylammonium)propane-1-sulfonic acid inner salt and lithium salt LiTFSI (the molar ratio of quaternary ammonium ionic sulfonate and LiTFSI is 1.1:1) are mixed in deionized water to form a lithium salt compound. After the reaction is complete, the mixture is repeatedly washed and then dried by rotary evaporation to obtain a yellow viscous liquid, which is the quaternary ammonium ion-coupled monomer.

[0078]

[0079] Step 3: Preparation of the precursor: Mix 5g of quaternary ammonium ion-coupled monomer, 1g of LiTFSI, 1.43g of 1,3-diisopropenylbenzene, 0.51g of ethoxylated trimethylolpropane triacrylate, and 0.21g of AIBN thermal initiator evenly to prepare a solvent-free high-rigidity polymer precursor; at this time, the lithium salt accounts for 20 wt% of the quaternary ammonium ion-coupled monomer, the molar ratio of 1,3-diisopropenylbenzene to the quaternary ammonium ion-coupled monomer is 1:1, the crosslinking agent ethoxylated trimethylolpropane triacrylate accounts for 8 wt% of the total mass of the quaternary ammonium ion-coupled monomer and 1,3-diisopropenylbenzene, and the thermal initiator AIBN accounts for 3 wt% of the total mass of the quaternary ammonium ion-coupled monomer, 1,3-diisopropenylbenzene, and ethoxylated trimethylolpropane triacrylate.

[0080] A solvent-free neutral polymer precursor was prepared by uniformly mixing 5 g of quaternary ammonium ion-coupled monomer, 1 g of LiTFSI, 0.95 g of 1,3-diisopropenylbenzene, 0.24 g of ethoxylated trimethylolpropane triacrylate, and 0.124 g of AIBN thermal initiator. At this stage, the lithium salt accounted for 20 wt% of the quaternary ammonium ion-coupled monomer, the molar ratio of 1,3-diisopropenylbenzene to the quaternary ammonium ion-coupled monomer was 2:3, the crosslinking agent ethoxylated trimethylolpropane triacrylate accounted for 4 wt% of the total mass of the quaternary ammonium ion-coupled monomer and 1,3-diisopropenylbenzene, and the AIBN thermal initiator accounted for 2 wt% of the total mass of the quaternary ammonium ion-coupled monomer, 1,3-diisopropenylbenzene, and ethoxylated trimethylolpropane triacrylate.

[0081] A solvent-free flexible polymer precursor was prepared by uniformly mixing 5 g of quaternary ammonium ion-coupled monomer, 1 g of LiTFSI, 0.48 g of 1,3-diisopropenylbenzene, 0.11 g of ethoxylated trimethylolpropane triacrylate, and 0.056 g of AIBN thermal initiator. In this preparation, the lithium salt accounted for 20 wt% of the quaternary ammonium ion-coupled monomer, the molar ratio of 1,3-diisopropenylbenzene to the quaternary ammonium ion-coupled monomer was 1:3, the crosslinking agent ethoxylated trimethylolpropane triacrylate accounted for 2 wt% of the total mass of the quaternary ammonium ion-coupled monomer and 1,3-diisopropenylbenzene, and AIBN accounted for 1 wt% of the total mass of the quaternary ammonium ion-coupled monomer, 1,3-diisopropenylbenzene, and ethoxylated trimethylolpropane triacrylate.

[0082] Step 4: Take 20 mL of solvent-free rigid polymer precursor and evenly brush it onto the surface of the lithium anode, with a coating thickness of 40 μm. Then, heat-cur it at 65℃ for 15 h in a vacuum environment to obtain a solidified anode sheet with a dense polymer layer on the surface. Apply 10 μL of solvent-free flexible polymer precursor evenly to the surface of the LFP cathode using a coating machine, controlling the coating thickness to 10 μm. Heat-cur it at 25℃ under vacuum for 4 h to improve the wettability of the precursor within the electrode sheet, thereby increasing the amount of precursor wetted. Then, heat-cur it at 65℃ for 15 h to obtain a solidified cathode sheet. The electrode sheet is then die-cut into small discs with a diameter of 12 mm for subsequent use.

[0083] A solidified positive electrode was placed inside the positive electrode shell, and a high-porosity PE separator was placed on top of the positive electrode. 60 μL of a solvent-free, medium-rigidity polymer precursor was added dropwise, and the mixture was subjected to negative pressure for 1 h to aid in its wetting inside the separator. Then, a solidified negative electrode was placed on top, the battery was assembled, and thermosetting was performed in a vacuum oven at 65°C for 15 h. This yielded a half-cell.

[0084] The polymer prepared in Example 1 is as follows: (Formula 9)

[0085] Example 2: The difference from Example 1 is that the molar ratio of the C12- or lower olefin derivative monomer containing at least one benzene ring substituent to the ion-coupled monomer in the solvent-free high-rigidity polymer precursor is 1:0.8; the crosslinking agent accounts for 8 wt% of the total mass of the ion-coupled monomer and the C12- or lower olefin derivative monomer containing at least one benzene ring substituent; and the initiator accounts for 3 wt% of the total mass of the ion-coupled monomer. In the solvent-free rigid polymer precursor, the molar ratio of C12 or less olefin derivative monomers containing at least one benzene ring substituent to ion-coupled monomers is 1:1.3; the crosslinking agent accounts for 4 wt% of the total mass of the ion-coupled monomers and the C12 or less olefin derivative monomers containing at least one benzene ring substituent; and the initiator accounts for 2 wt% of the total mass of the ion-coupled monomers. The solvent-free, low-rigidity polymer precursor contains a C12 or lower olefin derivative monomer with at least one benzene ring substituent group in a molar ratio of 1:2 to an ion-coupled monomer. The crosslinking agent accounts for 2 wt% of the total mass of the ion-coupled monomer and the C12 or lower olefin derivative monomer with at least one benzene ring substituent group, and the initiator accounts for 1 wt% of the total mass of the ion-coupled monomer.

[0086] Example 3: The difference from Example 1 is that the molar ratio of the C12- or lower olefin derivative monomer containing at least one benzene ring substituent to the ion-coupled monomer in the solvent-free high-rigidity polymer precursor is 1:0.9; the crosslinking agent accounts for 8 wt% of the total mass of the ion-coupled monomer and the C12- or lower olefin derivative monomer containing at least one benzene ring substituent; and the initiator accounts for 3 wt% of the mass of the ion-coupled monomer. In the solvent-free rigid polymer precursor, the molar ratio of C12 or less olefin derivative monomers containing at least one benzene ring substituent to ion-coupled monomers is 1:1.6; the crosslinking agent accounts for 4 wt% of the total mass of the ion-coupled monomers and C12 or less olefin derivative monomers containing at least one benzene ring substituent; and the initiator accounts for 2 wt% of the mass of the ion-coupled monomers. The solvent-free, low-rigidity polymer precursor contains a C12 or lower olefin derivative monomer with at least one benzene ring substituent group in a molar ratio of 1:2.5 to an ion-coupled monomer. The crosslinking agent accounts for 2 wt% of the total mass of the ion-coupled monomer and the C12 or lower olefin derivative monomer with at least one benzene ring substituent group, and the photoinitiator accounts for 1 wt% of the mass of the ion-coupled monomer.

[0087] Example 4: The difference from Example 1 is that dimethylaminoethyl acrylate is replaced with (2-dimethylaminobutyl acrylate).

[0088] Example 5: The difference from Example 1 is that ethoxylated trimethylolpropane triacrylate is replaced with bis(trimethylolpropane)tetraacrylate.

[0089] Example 6: The difference from Example 1 is that ethoxylated trimethylolpropane triacrylate is replaced with polyethylene glycol diacrylate.

[0090] Example 7: The difference from Example 1 is that the lithium salt in steps 2 and 3 is replaced with lithium tetrafluoroborate.

[0091] Example 8: The difference from Example 1 is that the desired ion-coupled monomer, as shown in Formula 5 in step one, was synthesized through a ring-opening reaction of dimethylaminoethyl acrylate and γ-butyrolactone. In a round-bottom flask, 5 g of dimethylaminoethyl acrylate, 3.31 g of γ-butyrolactone (molar ratio of dimethylaminoethyl acrylate to γ-butyrolactone was 1:1.1), and 50 mL of acetonitrile were added. After stirring, the mixture was heated to 50°C and reacted for 48 h to obtain a large amount of white precipitate. The precipitate was then allowed to stand at room temperature for 12 h, during which the product continued to increase. After standing, the product was filtered, repeatedly washed, and dried to obtain a quaternary ammonium ionic carboxylate: 4-((2-(acryloyloxy)ethyl)dimethylamino)butyrate.

[0092]

[0093] Example 9: The difference from Example 1 is that the thermosetting temperature is 60°C and the time is 13 hours.

[0094] Example 10: The difference from Example 1 is that the thermosetting temperature is 70°C and the time is 18 hours.

[0095] Comparative Example 1: The difference from Example 1 is that the thermosetting time in Example 1 is replaced with 10 h, while the rest remains the same.

[0096] Comparative Example 2: The difference from Example 1 is that the thermosetting time in Example 1 is replaced with 20 h, while the rest remains the same.

[0097] Comparative Example 3: The difference from Example 1 is that all solvent-free polymer precursors were replaced with solvent-free high-rigidity polymer precursors.

[0098] Comparative Example 4: The difference from Example 1 is that all solvent-free polymer precursors are replaced with solvent-free rigid polymer precursors.

[0099] Comparative Example 5: The difference from Example 1 is that all solvent-free polymer precursors were replaced with solvent-free low-rigidity polymer precursors.

[0100] Comparative Example 6: The difference from Example 1 is that in step one: the desired ion-coupled monomer was synthesized by the ring-opening reaction of dimethylaminoethyl acrylate and 1,3-propanesulfonic acid lactone; in a round-bottom flask, 5 g of dimethylaminoethyl acrylate, 4.7 g of 1,3-propanesulfonic acid lactone (the molar ratio of dimethylaminoethyl acrylate to 1,3-propanesulfonic acid lactone was 1:1.1) and 50 mL of acetonitrile were added, stirred evenly, and heated to 50°C. After reacting for 48 h, a large amount of white precipitate was obtained, and then allowed to stand at room temperature for 12 h, during which the product continued to increase. After standing, the product was filtered, repeatedly washed, and dried to obtain the quaternary ammonium ion sulfonate 3-((2-(acryloyloxy)ethyl)dimethylammonium)propane-1-sulfonic acid lactone; Step 2: Preparation of the precursor: 5 g of quaternary ammonium ion sulfonate, 3.53 g of LiTFSI, 1.43 g of 1,3-diisopropenylbenzene, 0.51 g of ethoxylated trimethylolpropane triacrylate, and 0.21 g of AIBN thermal initiator were mixed evenly in 5 mL of DME / acetonitrile solvent and dried in a vacuum oven at 40°C for 48 h to prepare a solvent-free high-rigidity polymer precursor. At this point, the lithium salt accounted for 20 wt% of the quaternary ammonium ion-coupled monomer, the molar ratio of 1,3-diisopropenylbenzene to the quaternary ammonium ion-coupled monomer was 1:1, the crosslinking agent ethoxylated trimethylolpropane triacrylate accounted for 8 wt% of the total mass of the quaternary ammonium ion-coupled monomer and 1,3-diisopropenylbenzene, and the thermal initiator AIBN accounted for 3 wt% of the total mass of the quaternary ammonium ion-coupled monomer, 1,3-diisopropenylbenzene, and ethoxylated trimethylolpropane triacrylate.

[0101] 5 g of quaternary ammonium ion sulfonate, 3.53 g of LiTFSI, 0.95 g of 1,3-diisopropenylbenzene, 0.24 g of ethoxylated trimethylolpropane triacrylate, and 0.124 g of AIBN thermal initiator were mixed evenly in 5 mL of DME / acetonitrile solvent and dried in a vacuum oven at 40°C for 48 h to prepare a solvent-free, medium-rigid polymer precursor. At this time, the lithium salt accounted for 20 wt% of the quaternary ammonium ion-coupled monomer, the molar ratio of 1,3-diisopropenylbenzene to the quaternary ammonium ion-coupled monomer was 2:3, the crosslinking agent ethoxylated trimethylolpropane triacrylate accounted for 4 wt% of the total mass of the quaternary ammonium ion-coupled monomer and 1,3-diisopropenylbenzene, and the AIBN thermal initiator accounted for 2 wt% of the total mass of the quaternary ammonium ion-coupled monomer, 1,3-diisopropenylbenzene, and ethoxylated trimethylolpropane triacrylate.

[0102] 5 g of quaternary ammonium ion sulfonate, 3.53 g of LiTFSI, 0.48 g of 1,3-diisopropenylbenzene, 0.11 g of ethoxylated trimethylolpropane triacrylate, and 0.056 g of AIBN thermal initiator were mixed evenly in 5 mL of DME / acetonitrile solvent and dried in a vacuum oven at 40°C for 48 h to prepare a solvent-free, low-rigidity polymer precursor. At this point, the lithium salt accounted for 20 wt% of the quaternary ammonium ion-coupled monomer, the molar ratio of 1,3-diisopropenylbenzene to the quaternary ammonium ion-coupled monomer was 1:3, the crosslinking agent ethoxylated trimethylolpropane triacrylate accounted for 2 wt% of the total mass of the quaternary ammonium ion-coupled monomer and 1,3-diisopropenylbenzene, and AIBN accounted for 1 wt% of the total mass of the quaternary ammonium ion-coupled monomer, 1,3-diisopropenylbenzene, and ethoxylated trimethylolpropane triacrylate.

[0103] Comparative Example 7: Unlike Example 1, 1,3-diisopropenylbenzene was replaced with polyoxyethylene ether.

[0104] Comparative Example 8: The amount of solvent-free rigid polymer precursor used in Example 1 was replaced with 40 mL.

[0105] Comparative Example 9: The coating thickness of the solvent-free flexible polymer precursor in Example 1 was adjusted to 15 mm.

[0106] Comparative Example 10: The amount of solvent-free neutral polymer precursor added in Example 1 was changed from 60 mL to 90 mL.

[0107] The following tests were performed on some of the embodiments and comparative examples in Examples 1-10 and Comparative Examples 1-10: (1) Tensile strength test: The precursors were added into polytetrafluoroethylene molds and heat-cured, i.e., heat-cured in a vacuum oven at 65°C for 15 h to prepare three polymer solid electrolyte membranes with different rigidities. The tensile strength of the membranes was then tested, and the test method was carried out in accordance with 6.5.1 of the national standard GB / T 36363-2018.

[0108] (2) Ionic conductivity test: Assemble the SS||SS battery and perform impedance test using EIS. The battery was assembled in the order of stainless steel gasket, high porosity PE membrane, 60 L solvent-free polymer precursor, and stainless steel gasket. After thermosetting, i.e., thermosetting in a vacuum oven at 65℃ for 15 h, an all-solid-state battery was obtained. The impedance was measured by EIS. After the test, the stainless steel battery was disassembled inside the glove box and the thickness of the membrane was measured with a thickness gauge. Based on the impedance and thickness, the ionic conductivity of different electrolyte membranes was calculated according to the formula.

[0109] (3) Battery impedance test and cycle performance test: After the battery is assembled, the battery impedance is tested, and the battery after impedance test is placed in a 25℃ battery test cabinet for charge and discharge cycle test. The test voltage range is 2.5 V~4.0 V, and the test rate is 0.1C cycle.

[0110] The mechanical properties of polymer solid electrolyte membranes are shown in Table 1 below: Table 1

[0111] Table 2

[0112] Table 3

[0113] As can be seen from the comparison of Examples 1-10 and Comparative Examples 1-10, the present invention uses an ABC-type block copolymer with gradient rigidity as a polymer solid electrolyte, wherein block A is a monomer of olefin derivatives below C12 containing at least one benzene ring substituent, block B is a crosslinking agent, and block C is an ion-coupled monomer; the block copolymer solid electrolyte provided based on in-situ polymerization and gradient rigidity design exhibits significant advantages in mechanical properties, ionic conductivity, and battery cycle stability.

[0114] As can be seen from Comparative Example 1, when the thermosetting time is shortened to 10 h, the polymerization reaction is incomplete, resulting in the tensile strength of the high, medium, and low rigidity polymers being significantly lower than that of Example 1. This indicates that insufficient curing time cannot allow the monomers in the precursor to fully polymerize and form a complete cross-linked network, and the molecular chain segment arrangement is not regular enough, thus weakening the mechanical support capacity of the material. Combined with the data in Table 3, the battery assembled using the scheme of Comparative Example 1 has a capacity retention rate of only 73.16% after 50 cycles at 0.1C, far lower than the 97.32% of Example 1. This is attributed to the electrolyte network structure defects caused by incomplete polymerization, which makes it difficult to effectively suppress lithium dendrite growth and maintain stable interfacial contact during long-term cycling.

[0115] As can be seen from Comparative Example 2, when the thermosetting time is extended to 20 h, although the tensile strength of the polymer increases, especially the tensile strength of the high-rigidity polymer reaches 613.78 Kgf / cm². 2However, the elongation at break decreases accordingly, indicating increased material brittleness. More importantly, this over-curing may lead to an overly dense cross-linked network, restricting the movement of polymer chain segments and thus adversely affecting lithium-ion migration. Example 1, through precise control of curing time and gradient rigidity design, ensured the overall ionic conductivity of the electrolyte while maintaining sufficient strength of the rigid polymer layer, achieving synergistic optimization of mechanical properties and ion conduction efficiency.

[0116] The comparison between Example 1 and Comparative Examples 3-5 clearly demonstrates the necessity of a gradient rigidity structure design. Comparative Examples 3-5 used single high, medium, and low rigidity precursors to prepare full cells, respectively, and their overall performance was inferior to the gradient structure scheme of Example 1. While the single high rigidity scheme provided sufficient mechanical strength, the ionic conductivity of each layer was generally low, and the interface compatibility was poor, resulting in a first-cycle discharge specific capacity of only 126.82 mAh / g. Comparative Example 5, using a single low rigidity scheme, achieved a relatively high first-cycle discharge specific capacity of 150.57 mAh / g, but its mechanical strength was insufficient to suppress lithium dendrites, causing the capacity retention to plummet to 80.76% after 50 cycles. In contrast, Example 1, by constructing a rigid polymer layer on the negative electrode side to physically block dendrites, setting a flexible layer on the positive electrode side to optimize interface contact, achieving a rigid gradient in the intermediate transition layer, and integrally molding through covalent bonds, effectively avoided the weak connection problem between multiple interfaces, achieving a first-cycle discharge specific capacity of 155.69 mAh / g and a high capacity retention of 97.32%.

[0117] As can be seen from Comparative Example 6, introducing solvents (DME / acetonitrile) during precursor preparation causes serious problems. Compared with the solvent-free system of Example 1, Comparative Example 6, although identical in monomer synthesis steps, used solvents in precursor preparation. The introduction of solvents not only increases process complexity but, more importantly, is difficult to completely remove during subsequent thermosetting. Residual solvent molecules occupy free volume in the polymer network, interfering with the continuous transport path of lithium ions and leading to a significant decrease in ionic conductivity. Simultaneously, solvent residues deteriorate the electrode / electrolyte interface, increasing interfacial side reactions and worsening battery cycle stability. The solvent-free design of Example 1, benefiting from the ion-coupled monomers themselves acting as a reaction medium, achieves molecular-level uniform mixing of components, fundamentally avoiding the solvent residue problem and ensuring the purity and structural integrity of the polymer electrolyte.

[0118] As can be seen from Comparative Example 7, the present invention, by limiting block A to a C12 or lower olefin derivative monomer containing at least one benzene ring substituent, is crucial for constructing a high-performance gradient rigid solid electrolyte. Comparative Example 7 replaced the rigid aromatic monomer (1,3-diisopropenylbenzene) in Example 1 with a flexible polyoxyethylene ether. Although polyoxyethylene ether possesses good lithium-ion solubility and chain segment mobility, the polymer electrolyte constructed from it exhibits significant deterioration in mechanical properties. Combining the data in Tables 1 and 3, it can be inferred that the tensile strength of the high, medium, and flexible polymer layers of the electrolyte prepared by the Comparative Example 7 scheme is far lower than the corresponding values ​​in Example 1. This is because the polyoxyethylene ether segments lack the inherent rigid framework of the aromatic ring structure, failing to provide effective physical support points for the polymer network, resulting in a decrease in the overall rigidity of the material. This insufficient mechanical strength is directly reflected in the battery cycle performance; the battery assembled in Comparative Example 7 has a capacity retention rate of only 63.35% after 50 cycles at 0.1C, significantly lower than the 97.32% in Example 1. This is attributed to the lack of effective physical barriers from a high-rigidity rigid layer, allowing lithium dendrites to penetrate the electrolyte membrane more easily, triggering internal micro-short circuits and accelerating capacity decay.

[0119] As can be seen from Comparative Example 8, when the amount of solvent-free high-rigidity polymer precursor coated on the negative electrode side was increased from 20 μL to 40 μL, although the thickness of the rigid polymer layer increased, theoretically providing a stronger physical barrier to suppress lithium dendrites, the overall performance of the battery significantly deteriorated. Combined with the data in Table 3, the first-cycle discharge specific capacity of the battery assembled in Comparative Example 8 decreased to 105.48 mAh / g, and the capacity retention rate after 50 cycles at 0.1C was only 75.13%, far lower than the 97.32% of Example 1. This result indicates that while an excessively thick rigid layer enhances mechanical barrier capability, it also increases the migration distance of lithium ions from the negative electrode to the electrolyte and the interfacial resistance, leading to decreased ion transport efficiency, increased polarization, and limited capacity utilization. This invention achieves the optimal balance between mechanical strength and ion transport efficiency by controlling the amount of rigid layer within a certain range, effectively suppressing lithium dendrites while ensuring rapid lithium ion migration.

[0120] As can be seen from Comparative Example 9, when the coating thickness of the solvent-free low-rigidity polymer precursor on the positive electrode side is increased from 10 μm to 15 μm, although the thicker flexible layer theoretically provides better positive electrode interface adhesion, the battery performance is not further improved. The battery assembled in Comparative Example 9 has a first-cycle discharge specific capacity of 114.11 mAh / g and a capacity retention rate of 89.30% after 50 cycles at 0.1C, both of which are lower than those in Example 1. This phenomenon indicates that although an excessively thick flexible layer improves interface contact, it also increases the path length of ion transport on the positive electrode side. Furthermore, while the flexible polymer layer itself has high ionic conductivity, excessive layer thickness leads to an increase in the overall internal resistance of the battery. In addition, an excessively thick flexible layer may not provide sufficient mechanical support for the intermediate transition layer, disrupting the continuous transition of the gradient rigid structure from the intermediate layer to the positive electrode side, resulting in stress mismatch at the interface and affecting the long-term cycle stability of the battery.

[0121] As can be seen from Comparative Example 10, when the amount of solvent-free, medium-rigid polymer precursor injected into the diaphragm was increased from 60 μL to 90 μL, although the initial discharge specific capacity slightly improved, the capacity retention rate after 50 cycles at 0.1C decreased to 80.08%, lower than the 97.32% in Example 1. This result indicates that while an excessive amount of intermediate layer precursor can more fully wet the diaphragm and electrode interface, helping to reduce interfacial impedance and improve initial capacity in the short term, an excessively thick intermediate layer may lead to an increase in the overall thickness of the electrolyte membrane after curing, thus prolonging the ion transport path. Simultaneously, the volume shrinkage of the excessive precursor during curing may introduce internal stress, disrupting the structural integrity of the gradient rigid layer and affecting long-term cycling stability.

[0122] Depend on Figure 1 As can be seen, the ion-coupled monomer prepared in Example 1 of this invention was successfully prepared by characterizing its structure with 1H NMR.

[0123] Combined with Table 3 and Figure 3 It can be seen that Example 1 exhibits excellent cycling performance in the first 50 cycles at 0.1C, with a capacity retention of 97.32% after 50 cycles at 0.1C. Depend on Figure 2As can be seen, Sample 1 is the product of step 2 in Example 1. After the quaternary ammonium ion-coupled monomer (5 g), LiTFSI (1 g), and AIBN (0.1 g) are mixed evenly and then heat-cured for 15 h, the mass loss graph shows no mass loss. Sample 2 is the product of step 1 in Example 1. The quaternary ammonium ion sulfonate 3-((2-(acryloyloxy)ethyl)dimethylammonium)propane-1-sulfonic acid inner salt (2.46 g), LiTFSI (3.54 g), AIBN (0.1 g), and DME / acetonitrile (1 ml) are mixed evenly to form a transparent solution. After removing DME / acetonitrile under vacuum negative pressure for 24 h until the mass no longer decreases, and then heat-cured for 15 h, the mass loss graph shows that there is mass loss, indicating that DME / acetonitrile cannot be completely removed. Therefore, this invention innovatively employs a step-by-step precursor preparation method. In the first step, an ion-coupled monomer is prepared. This avoids the need for solvents to dissolve and form a complex system in subsequent precursor preparation, and also avoids the problem of residues in the subsequent solvent removal process. Under the step-by-step preparation method, the target ion-coupled monomer can be obtained by using water as the reaction medium in S1 of this invention. Moreover, the product is directly liquid after washing and drying, which can be used to dissolve lithium salts to prepare solutions. This avoids the problem in the prior art where DME, acetonitrile, and other solvents are added to provide a reaction medium for the formation of ion-coupled monomers when blending quaternary ammonium ion oxyanion salts (such as quaternary ammonium ion sulfonates), lithium salts, crosslinking agents, and other components as a precursor. Furthermore, DME and other solvents still leave residues under conditions such as evaporation and drying.

[0124] A comparison of Examples 1, 3, and 2 shows that this invention further achieves targeted control over the crosslinking density and mechanical properties of the final polymer electrolyte by precisely controlling the ratio of ion-coupled monomers, C12- or lower olefin derivative monomers containing at least one benzene ring substituent, and crosslinking agents in the precursor. Specifically, increasing the amount of C12- or lower olefin derivative monomers containing at least one benzene ring substituent promotes the formation of rigid blocks, improving the rigidity of the material; increasing the amount of crosslinking agent increases the crosslinking density of the network, further enhancing mechanical strength; while the content of ion-coupled monomers directly affects the density of lithium-ion conduction sites, the degree of crosslinking polymerization, and self-healing ability. Through the synergistic control of these three components, tensile strength can be improved while maintaining high ionic conductivity, effectively overcoming the performance bottlenecks of traditional polymer electrolytes.

[0125] A comparison of Examples 1 and 4 shows that the present invention further optimizes the groups R1 and R2 in the ion-coupled monomer. In this case, the shorter straight-chain alkyl group effectively reduces the steric hindrance of the molecular chain segments, enhances the ion-pair dissociation ability between the quaternary ammonium cation and the oxyanion, thereby promoting the rapid migration of lithium ions. Simultaneously, the short-chain alkyl structure helps improve the reactivity of the monomer during polymerization, making the polymerization reaction easier to control, and resulting in a more regular arrangement of polymer chain segments, which is beneficial for constructing continuous, low-torsion ion conduction channels. Furthermore, the smaller alkyl volume can reduce the adverse effects on the flexibility of the polymer backbone, avoiding restricted chain movement due to steric hindrance, thus maintaining high ion mobility while ensuring mechanical strength, further improving the room-temperature ionic conductivity and interfacial stability of the electrolyte.

[0126] As can be seen from the comparison between Examples 1 and Examples 5-6, the present invention further optimizes the crosslinking agent. The triacrylate crosslinking agent can construct a moderately crosslinked three-dimensional network structure during polymerization. Compared with diacrylate crosslinking agents, triacrylate can form a more stable and complete crosslinked network, providing higher mechanical strength and structural stability; compared with tetraacrylate or higher functionality crosslinking agents, triacrylate has a moderate crosslinking density, avoiding problems such as excessive rigidity, increased brittleness, and restricted ionic chain movement caused by excessive crosslinking. This moderately crosslinked network structure can achieve a further balance between mechanical strength and ion conduction efficiency.

[0127] A comparison of Examples 1 and 7 shows that the present invention further enhances the synergistic effect between the ion-coupled structure and the lithium salt by optimizing the lithium salt type. Example 1 uses lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), whose large-size, highly delocalized anionic structure not only forms a stable ion cluster with the ion-coupled monomer, effectively shielding the electrostatic attraction between the quaternary ammonium cation and the sulfonic acid anion, but also, through a moderate ion pair dissociation balance, enables the dynamic physical cross-linked network to maintain structural integrity and possess self-healing capabilities.

[0128] A comparison of Examples 1 and 8 shows that the present invention further selects an ion-coupled monomer with sulfonate anions, which has a stronger electron-withdrawing inductive effect and a higher degree of charge delocalization compared to anions such as carboxylate anions. The sulfur atom in the sulfonate group is in a high valence state, and its negative charge is effectively dispersed through the resonance structure of three oxygen atoms, resulting in a lower binding energy between lithium ions and anions in the lithium sulfonate salt, making it easier for lithium ions to dissociate and migrate.

[0129] In summary, this invention successfully solves the technical challenges of traditional polymer electrolytes, such as the difficulty in simultaneously achieving high ionic conductivity and mechanical strength, poor solid-solid interface contact, and poor long-term cycle stability, through a unique ABC-type block copolymer molecular design, a solvent-free precursor system, and an in-situ polymerization-induced gradient rigidity construction process. The prepared solid-state battery exhibits excellent overall performance at room temperature, highlighting the significant value of this invention in promoting the practical application of high-safety, high-energy-density solid-state batteries.

[0130] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions, and variations to the above embodiments within the scope of the present invention. Furthermore, without contradiction, those skilled in the art can combine and integrate different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design, characterized in that, The block copolymer solid electrolyte comprises polymer layers with gradient rigidity along the thickness direction. Each polymer layer has an ABC-type block copolymer, wherein block A is a monomer of an olefin derivative with at least one benzene ring substituent group below C12, block B is a crosslinking agent, and block C is an ion-coupled monomer. The gradient rigidity between the polymer layers is adjusted by changing the ratio of each block in the ABC-type block copolymer. The ion-coupled monomer is selected from compounds of formula 1 or formula 2, wherein R1 and R2 are each independently selected from substituted or unsubstituted C2-C4 alkyl chains, and when R1 or R2 is substituted, the substituent group is selected from one or more of C1-C3 alkyl, C1-C3 alkoxy, carboxyl, and phosphoryl groups, wherein M - X is selected from one of the lithium salt anionic groups. - R9 is selected from one of the anionic ligand functional groups, wherein R9 is selected from one of the C0-C3 alkyl groups; ； The crosslinking agent is selected from one of the polyol acrylate compounds.

2. The block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design according to claim 1, characterized in that, The polymer layer with gradient rigidity includes a rigid polymer layer on the negative electrode side, a flexible polymer layer on the positive electrode side, and a neutral polymer layer located in the pores of the positive and negative electrode separator.

3. The block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design according to claim 1, characterized in that, The C12 or smaller olefin derivative monomer containing at least one benzene ring substituent is selected from the compounds of Formula 3. ， R3, R4, and R5 are each independently selected from one or more of the following: hydrogen atom, C1-C2 alkyl group, C1-C2 alkoxy group, amino group, hydroxyl group, cyano group, carboxyl group, acyl group, and halogen atom. R3 is attached to any position on the benzene ring except for the carbon atom attached to the alkenyl chain; n is an integer from 0 to 4.

4. The block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design according to claim 1, characterized in that, The anion ligand functional group X - It is selected from one of the functional groups of oxyanionic ligands containing oxyanions; Preferably, the oxyanionic ligand functional group includes one of carboxylate ions, sulfonate ions, phosphonate ions, and sulfate ions; More preferably, the anionic ligand functional group X - It is a sulfonate ion.

5. The block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design according to claim 1, characterized in that, In the ion-coupled monomer, R1 and R2 are each independently selected from one of the C2-C3 straight-chain alkyl groups; Preferably, the polyol acrylate is selected from one or more of polyol triacrylate and polyol tetraacrylate; More preferably, the ion-coupled monomer is selected from compounds of formula 1, wherein R1 and R2 are each independently selected from an unsubstituted C2-C3 straight-chain alkyl group, and M... - The crosslinking agent is selected from one of the lithium salt anionic groups, wherein the anionic ligand functional group is a sulfonate ion, the crosslinking agent is selected from one of the polyol triacrylates, and the olefin derivative monomer containing at least one benzene ring substituent is selected from one of the compounds with the structure of Formula 2, wherein R3 is a hydrogen atom, n=0, and R5 is selected from one or more of hydrogen atoms and C1~C2 alkyl groups.

6. The block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design according to claim 1, characterized in that, The tensile strength of the rigid polymer layer is 300~600 Kgf / cm. 2 The tensile strength of the neutral polymer layer is 100~300 Kgf / cm. 2 The tensile strength of the flexible polymer layer is 30~100 Kgf / cm. 2 ; Preferably, the tensile strength of the rigid polymer layer is 400-500 kgf / cm². 2 The tensile strength of the neutral polymer layer is 200-300 Kgf / cm. 2 The tensile strength of the flexible polymer layer is 50-80 kgf / cm². 2 ; Preferably, the ionic conductivity of the rigid polymer layer is ≥1.8×10⁻⁶. -4 S cm -1 The ionic conductivity of the neutral polymer layer is ≥2.3 ×10⁻⁶. -4 S cm -1 The ionic conductivity of the flexible polymer layer is ≥2.7 ×10⁻⁶. -4 S cm -1 .

7. A solvent-free polymer precursor, characterized in that, The solvent-free polymer precursor is used to prepare the block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design as described in any one of claims 1 to 6. The solvent-free polymer precursor includes an ion-coupled monomer, an olefin derivative monomer containing at least one benzene ring substituent, a crosslinking agent, an initiator, and a second lithium salt.

8. The solvent-free polymer precursor according to claim 7, characterized in that, By changing the proportion of each component in the solvent-free polymer precursor, a solvent-free rigid polymer precursor for preparing the rigid polymer layer, a solvent-free neutral polymer precursor for preparing the neutral polymer layer, and a solvent-free flexible polymer precursor for preparing the flexible polymer layer can be obtained.

9. A solidified electrode comprising the block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design as described in any one of claims 1 to 6, characterized in that, The solidified electrode includes a positive solidified electrode and a negative solidified electrode. The positive solidified electrode includes a positive electrode impregnated with a flexible polymer layer, and the negative solidified electrode includes a negative electrode impregnated with a rigid polymer layer.

10. An all-solid-state battery, characterized in that, The all-solid-state battery includes the block copolymer solid electrolyte based on in-situ polymerization and gradient rigidity design as described in any one of claims 1 to 6.

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