High-voltage chloride solid electrolyte with stable in-situ polyacrylonitrile flexible ion transmission interface layer and preparation method and application of high-voltage chloride solid electrolyte

Abstract

The invention discloses a high-voltage chloride solid electrolyte with a stable in-situ polyacrylonitrile flexible ion transmission interface layer and a preparation method and application thereof, and belongs to the technical field of solid electrolytes. According to the invention, an in-situ polymerization reaction is initiated by using polyvalent central metal ions contained in a specific chloride solid electrolyte to generate an electrophilic induction effect on a nitrile monomer, so that a uniform and complete polyacrylonitrile artificial organic flexible ionic conductor interface layer is formed on the surface of the chloride solid electrolyte; and the crystal structure and the ionic conductivity of the chloride solid electrolyte are not damaged. The lossless interface layer can effectively enhance the electrochemical stability of the solid electrolyte, can be matched with a high-voltage lithium ion positive electrode material, can enhance the air stability of the electrolyte and the mechanical stability of an electrode-electrolyte interface, and can remarkably inhibit the generation of pores and electrode cracks at the interface; the rate capability and the cycle life of the lithium ion solid-state battery are improved.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte technology, specifically to a high-voltage chloride solid electrolyte with an in-situ polynitrile flexible ion transport interface layer, its preparation method, and its applications. Background Technology

[0002] In recent years, with the rapid development of electric vehicles and 3C consumer electronics, people have increasingly higher performance requirements for chemical energy storage devices such as lithium-ion batteries. Traditional lithium-ion batteries, limited by the energy density of the selected positive and negative electrode materials and the inherent flammability of the electrolyte, face a predicament of insufficient energy density and safety that urgently needs to be overcome. Among numerous potential technologies, solid-state batteries are widely considered a strong candidate for the next generation of advanced lithium batteries, mainly due to the following aspects: First, solid-state batteries are expected to significantly improve energy density and can be matched with high-energy-density positive and negative electrode active materials; second, the solid electrolyte used in solid-state batteries has intrinsic safety, good thermal stability, and is not flammable; third, the separator in solid-state batteries is the electrolyte, and bipolar stacking can be used, which is expected to improve pack efficiency. Due to the inherently narrow electrochemical window, solid electrolytes often undergo redox reactions and rapidly degrade when matched with common commercial positive and negative electrode materials. This is especially true for high-voltage positive electrode materials, where the oxidative deactivation of solid electrolytes is particularly severe at high potentials. To address this problem, a common approach is to coat the surface of the solid electrode with an electronic insulating layer to suppress redox reactions and rely on kinetic interface stabilization.

[0003] For example, Janek et al. proposed in ACS Energy Lett. (2023, 8, 1322-1329) to use in-situ generated Li2SO4 to coat the cathode material NCM85 to prevent the degradation of the cathode-electrolyte interface in sulfide solid-state batteries; Arumugam et al. used Li3PO4 to coat iron-doped LiNi in Small (2024, 20, 2306053). 0.5 Mn 1.5 O4 materials achieved stable cycling at high potentials. Neil et al., in Nat Commun. (2024, 15, 10233), deposited a 5 nm thick amorphous Nb2O5 passivation layer using atomic layer deposition (ALD), which mitigated the decomposition reaction between the electrolyte and electrode materials to some extent. Based on the above existing design schemes, it is known that the interfacial protective layer constructed between the cathode and the solid electrolyte needs to simultaneously satisfy stability, electronic insulation, conformability, and ionic conductivity, and should not hinder electron transport between cathode materials.

[0004] However, traditional interface protection strategies often involve surface modification of the cathode, specifically chemically coating the cathode material with inorganic coatings. However, achieving uniform modification is difficult, resulting in limited protective effects. Some researchers have employed methods such as atomic layer deposition (ALD) or chemical vapor deposition (CVD) to improve modification uniformity, but these methods remain complex and costly. More importantly, when electronically insulating inorganic coatings are applied to the cathode surface, electron transport between electrode materials is hindered. Furthermore, inorganic coatings cannot effectively address the stress-strain issues at the solid-state interface. This is because solid-state batteries do not contain liquid components; therefore, a lack of good solid-solid physical contact between electrode and electrolyte materials directly leads to difficulties in carrier transport, significantly increased interfacial impedance, and a significant decline in solid-state battery performance.

[0005] In summary, conventional methods for modifying cathodes currently available in this field have considerable limitations. On the other hand, while most methods for modifying electrolytes can partially alleviate the aforementioned problems, they are either immature, costly, complex, or cause irreversible damage to electrolyte materials, resulting in a loss of ionic conductivity. Therefore, there is an urgent need to develop a mild, controllable, cost-effective, simple, and non-destructive electrolyte stabilization scheme. Summary of the Invention

[0006] In view of the above-mentioned deficiencies of the prior art, in a first aspect of the present invention, a method for preparing a high-voltage chloride solid electrolyte with a stable in-situ polyacrylonitrile flexible ion transport interface layer is provided, comprising the following steps: A high-voltage solid chloride electrolyte is obtained by mixing a chloride solid electrolyte with a precursor solution containing nitrile monomers and using the metal central ion of the chloride solid electrolyte to initiate the in-situ polymerization reaction of the nitrile monomers, forming a polymer layer on the surface of the chloride solid electrolyte. The chloride solid electrolyte includes lithium indium chloride (Li3InCl6), lithium yttrium chloride (Li3YCl6), lithium zirconium chloride (Li2ZrCl6), and lithium indium scandium chloride (Li2In). 0.333 Sc 0.333 Cl4, lithium, tantalum, lanthanum, chlorine, Li 0.388 Ta 0.238 La 0.475 At least one of Cl3, or a variant of a chloride solid electrolyte obtained by transforming a multivalent central metal coordination ion.

[0007] This application is designed based on existing technologies in the field that utilize in-situ polymerization to form solid electrolytes. For example, CN117878396A (An in-situ polymer-based solid electrolyte membrane and its preparation method) uses polymer monomers, fast-ion conductor organic ionic liquids, and electrolyte salts as raw materials, without involving the addition of an initiator. CN119920971A (In-situ polymer-modified polymer solid electrolyte, its preparation method, membrane-free lithium secondary battery, and lithium secondary battery) introduces unsaturated nitrile monomers with specific structures into polymer materials and polymerizes them in-situ in the polymer material under the action of an initiator. CN119627208A (In-situ polymerized dioxolane polymer solid electrolyte, magnesium fluoride interface layer, battery, and preparation method) utilizes magnesium ions to initiate in-situ polymerization to obtain a polydioxolane composite polymer solid electrolyte. It is important to note that, unlike the raw material selection and metal initiation mechanism of existing technologies, the design of this invention considers the existence of a certain coordination equilibrium between polyvalent metal central ions with large radii, such as [MCl6]↔[MCl5]. + +Cl - This equilibrium is extremely biased to the left. Under normal conditions, Cl... - The energy barrier to participate in the polymerization reaction is too high, and the reaction cannot be initiated and an artificial interface protective layer can not be formed when using only simple chlorine-containing substances (such as LiCl, NaCl, etc.). In contrast, the large-radius multivalent central metal M (M has empty orbitals) in the chloride solid electrolyte structure selected in this design has a strong polarization effect on the CN group (M---N-CR) containing lone pair electrons in specific nitrile monomers under partially non-destructive solvent conditions, thus affecting their electron cloud distribution and releasing trace amounts of Cl. - Under this polarization, it can attack monomers to form carbanions R. - The chain continues to attack the next monomer molecule, thus achieving chain growth and forming stable cyano polymers and their derivatives on the surface of the chloride solid electrolyte, serving as an ion transport layer, a flexible stress buffer layer, and a physical barrier layer. In this scheme, large-radius multivalent metal ions, Cl ions, nitrile monomers with attack sites, and non-destructive solvents play unique roles. The selected chloride solid electrolyte serves as both the reaction target and the reaction initiator; the chloride solid electrolyte contains a high lithium ion concentration, creating a lithium ion concentration gradient for the formed nanoscale ultrathin polynitrile artificial interface layer, which can spontaneously inject a certain amount of lithium ions into the interface layer. The lithium ions coordinate with the N in the polynitrile, and ultimately, this interface layer serves as both an interface stabilization layer and an interface transport layer with a certain lithium ion transport capability.

[0008] Preferably, the nitrile monomer includes at least one selected from ethyl 2-cyanoacrylate, acrylonitrile, 2-ethyl cyanoacrylate, ethylene glycol monomethyl ether 2-cyanoacrylate, ethyl isocyanate, ethyl isocyanate methacrylate, butyl 2-cyano-2-acrylate, ethyl 2-cyano-3-ethoxyacrylate, ethyl 2-cyano-3-ethoxycrotonate, and methyl 2-cyano-3-phenylacrylate.

[0009] Preferably, the molar ratio of the chloride solid electrolyte to the nitrile monomer is 5~50:1.

[0010] Preferably, the precursor solution is prepared by dissolving a nitrile monomer in an ether solvent; the molar ratio of the ether solvent to the nitrile monomer is controlled to be 1~100:1.

[0011] Ether solvents have the characteristic of low polarity, which can effectively reduce the damage of the solvent itself to the solid electrolyte in this invention.

[0012] More preferably, the ether solvent includes at least one selected from anisole, 2,2,2-trifluoroethyl ether, 1-chloro-2,2,2-trifluoroethyl difluoromethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, and 1,2-dimethyltetrahydrofuran.

[0013] Preferably, the in-situ polymerization reaction is carried out at a temperature of 20-60 °C for 1-12 h.

[0014] The temperature can be flexibly adjusted according to variables such as monomer activity and the degree of polarization of the chloride solid electrolyte. For example, in a preferred case, the reaction temperature is controlled at 20~60 °C; the reaction time can also be adjusted relatively flexibly according to the desired thickness of the modified layer, and in a preferred case, the reaction time can be controlled at 1~12 h.

[0015] Preferably, after the in-situ polymerization reaction is completed, the product is further purified by washing and drying to obtain a high-voltage chloride solid electrolyte.

[0016] In a second aspect of the present invention, a high-voltage chloride solid electrolyte with high chemical / electrochemical stability, high ionic conductivity, and excellent conformability is provided, which is prepared by the preparation method of the first aspect of the present invention.

[0017] In a third aspect of the invention, the application of the high-voltage chloride solid electrolyte of the second aspect of the invention is provided, including: using it as a solid electrolyte in the preparation of a full cell.

[0018] Preferably, the positive electrode material of the full battery includes at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese iron phosphate, lithium-rich manganese-based materials, ternary lithium nickel cobalt manganese oxide, and ternary lithium nickel cobalt aluminum oxide; the negative electrode material includes at least one of lithium aluminum alloy, lithium indium alloy, silicon negative electrode, silicon carbon negative electrode, and lithium metal.

[0019] High-voltage chloride solid electrolytes are used in the preparation of lithium-ion batteries, solid-state batteries or other types of full cells. The corresponding positive and negative electrodes can be made of materials commonly used in this field, so that the full cell has excellent electrical performance.

[0020] Based on the above technical solutions, the design concept and principle of this invention are as follows: This invention utilizes the numerous uniform reaction / induction sites on the surface of a chloride solid electrolyte to initiate an in-situ polymerization reaction between nitrile monomers using a central ion and its chloride content. This results in the formation of a highly stable, ultrathin, nanoscale flexible polynitrile ion transport layer on the chloride solid electrolyte surface. The process uses the solid electrolyte itself as the reaction initiator without the need for additional initiators, and the reaction is mild, controllable, and simple.

[0021] The above effects are mainly reflected in three important aspects: I. Development and Selection of Chloride Solid Electrolytes with Different Multivalent Metal Center Ions: This scheme investigates and optimizes various aspects, including cost, polarization / initiation efficiency, and bulk ion transport capability. For example, Li3InCl6, as the most common chloride solid electrolyte, is simple to synthesize and has high ionic conductivity. In... 3+ Ion-polarized monomers can initiate reactions at remarkably high rates. For example, Li₂ZrCl₄, despite its slightly lower ionic conductivity, exhibits high Zr content. 4+ With higher charge numbers (stronger electrophilic polarization) and lower costs, they improve initiation efficiency while reducing reaction time and the input energy (light, heat, electricity, etc.) required for the reaction. Other multivalent metal ions such as La, Sc, and Y also have the potential for multifunctional expansion, such as resisting reduction decomposition of alloy anodes, improving interfacial ion transport, and suppressing side reactions with other electrolyte systems (such as sulfide systems).

[0022] II. Monomer Selection: This scheme investigates and selects monomers based on factors such as cost, reaction ease, antioxidant properties after forming the artificial protective layer, elastic conformability, and mechanical strength. For example, using a polyacrylonitrile artificial buffer protective layer can completely and uniformly coat the surface of the chloride solid electrolyte, ensuring high ionic conductivity at the interface, enhancing the chemical stability of the stabilized chloride solid electrolyte, and broadening the electrochemical window of the electrolyte, allowing it to withstand high potentials without decomposition. Furthermore, based on different application scenarios and operating conditions, this scheme selects a variety of nitrile monomers to ensure the stabilization layer has multifunctionality and good environmental adaptability under different operating conditions. For instance, using ethyl 2-cyanoacrylate with electron-withdrawing groups as a monomer, compared to acrylonitrile, it has a faster response speed and better elastic deformation capability, significantly improving the mechanical stability of the cathode-solid electrolyte interface, reducing the likelihood of interface separation and electrode cracking, and significantly improving the cycle and rate performance of the lithium-ion solid composite cathode. For example, using methyl 2-cyano-3-phenylacrylate with a benzene ring structure as a monomer results in a more robust polyacrylonitrile artificial stabilized layer that is less prone to breakage during cycling. The benzene ring structure also allows for a larger volume of this polyacrylonitrile network, higher coverage efficiency, and less raw material consumption.

[0023] III. Matching with Low-Polar Solvents: Most solvents have a destructive effect on chloride solid electrolytes, reacting before the monomers and damaging the electrolyte's structure and ionic conductivity. This scheme prioritizes non-polar or low-polar solvents with high chemical stability that do not react with chloride solid electrolytes, considering factors such as chemical stability, cost, volatility efficiency, difficulty of impurity removal, and monomer compatibility. For example, anisole is relatively inexpensive, has a considerable monomer-dissolving capacity, and does not significantly damage the chloride solid electrolyte in a short period. Another example is 1-chloro-2,2,2-trifluoroethyl difluoromethyl ether, which has decent dissolving capacity, high volatility with minimal residue, simple post-treatment without high-temperature drying, and stable properties; even after mixing with chloride solid electrolytes for tens of hours, it does not significantly affect the electrolyte's ionic conductivity. Other solvents also possess various abilities to broaden reaction conditions, such as increasing the tolerance temperature of reactants and extending the electrolyte's tolerance time.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention provides a method for preparing a high-voltage chloride solid electrolyte with an in-situ stable polynitrile flexible ion transport interface layer. This method is based on the in-situ polymerization reaction between the central ion of the chloride solid electrolyte and the nitrile monomer, without destroying the solid electrolyte itself and without affecting its ionic conductivity and crystal structure. This method does not require additional initiators or harsh high-temperature treatment processes, the reaction conditions are mild and controllable, and the preparation process is simple and efficient.

[0025] This invention provides a high-voltage chloride solid electrolyte with high ionic conductivity, excellent elastic deformation capability, and good interfacial stability with a matching positive electrode, enabling the solid electrode to have excellent cycle stability and rate performance.

[0026] This invention provides an application of a high-voltage chloride solid electrolyte, which has strong adaptability and great potential for commercial application. Attached Figure Description

[0027] Figure 1 This is a transmission electron microscope (TEM) image of the high-voltage chloride solid electrolyte of Example 1; Figure 2 The Fourier transform infrared spectroscopy (FT-IR) spectra of the experimental and control groups in Example 2 are shown. Figure 3 The results of the rate performance tests for the experimental and control groups in Example 3 are shown. The test rates were set to 0.1 C, 0.2 C, 0.5 C, 1 C, 2 C, and 4 C, with a voltage range of 2.8~4.3 V (vs Li). + / Li); Figure 4 This example compares the first-week charge-discharge capacity of the experimental and control groups in Example 5 at a current density of 0.1 C, with a voltage range of 2.8~4.5V (vs Li). + / Li); Figure 5 The results of the rate performance tests for the experimental and control groups in Example 5 are shown. The test rates were set to 0.1C, 0.2C, 0.5C, 1C, 2C, and 4C, with a voltage range of 2.8~4.3 V (vs Li). + / Li); Figure 6 This example compares the charge-discharge cycle capacity of the experimental group and the control group in Example 5 at high voltage and 2C rate, with a voltage range of 2.8~4.5 V (vs Li). + / Li); Figure 7 For the comparison of the coulombic efficiency of the experimental group and the blank group during charge-discharge cycles in Example 5, the voltage range is 2.8~4.5V (vs Li + / Li). Detailed Implementation

[0028] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0029] Chloride solid electrolytes can be commercially available products or homemade. The preparation method of the chloride solid electrolyte used in the following examples is as follows: LiCl and MCl3 (M being the corresponding metal ion) were mixed in a stoichiometric ratio, placed in a ball mill jar, and ball-milled in a planetary ball mill at 400 rpm for 16 h (ball-to-material ratio 20:1). Subsequently, the mixture was vacuum sintered at 260 °C for 12 h, and then pulverized and ground to obtain the solid electrolyte powders.

[0030] Example 1 This embodiment provides a method for preparing a high-voltage Li3YCl6 solid electrolyte with an in-situ polynitrile flexible ion transport interface layer, the steps of which are as follows: Ethyl 2-cyanoacrylate was dissolved in 2,2,2-trifluoroethyl ether at a molar ratio of 1:75 to form a homogeneous precursor solution. Then, 10 g of solid electrolyte powder Li3YCl6 was added to 50 mL of the precursor solution and shaken uniformly. The solution was stirred at 300 rpm for 1 h at 20 ℃. After centrifugation to remove excess solution, the solution was vacuum dried for 12 h. Finally, the solid was ground to obtain polyacrylonitrile-stable high-voltage Li3YCl6 solid electrolyte.

[0031] In this embodiment, transmission electron microscopy was used to observe the microstructure of the prepared high-voltage Li3YCl6 solid electrolyte surface. Figure 1 Transmission electron microscopy (TEM) images of Li3YCl6 particles modified in situ with ethyl 2-cyanoacrylate are shown. The images show that a polyacrylonitrile stabilization layer uniformly protects the Li3YCl6 particles, with a thickness of approximately 20–30 nm.

[0032] Example 2 This embodiment provides a method for preparing a high-voltage Li₂ZrCl₆ solid electrolyte with an in-situ polynitrile flexible ion transport interface layer, the steps of which are as follows: Acrylonitrile was dissolved in 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether at a molar ratio of 1:10 to form a homogeneous precursor solution. Then, 10 g of solid electrolyte powder Li2ZrCl6 was added to 50 mL of the precursor solution and shaken uniformly. The solution was stirred at 300 rpm for 3 h at 30 ℃. After centrifugation to remove excess solution, the solution was vacuum dried for 12 h. Finally, the solid was ground to obtain polyacrylonitrile-stable high-voltage Li2ZrCl6 solid electrolyte.

[0033] This embodiment uses Fourier transform infrared spectroscopy to collect information on the characteristic functional groups contained in the prepared high-voltage Li₂ZrCl₆ solid electrolyte. For example... Figure 2 As shown, by comparison, the solid electrolyte of the experimental group modified with acrylonitrile has a performance of approximately 2250 cm⁻¹. -1 A strong absorption peak appeared at the wavenumber, corresponding to the presence of the cyano functional group, confirming the successful formation of the polynitrile product.

[0034] Example 3 This embodiment provides a method for preparing a high-voltage Li3InCl6 solid electrolyte with an in-situ stable polynitrile flexible ion transport interface layer. The steps are as follows: 2-Ethyl cyanoacrylate was dissolved in 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether at a molar ratio of 1:25. After complete dissolution, a homogeneous precursor solution was formed. Then, 10 g of solid electrolyte powder Li3InCl6 was added to 50 mL of the precursor solution and shaken uniformly. The solution was stirred at 300 rpm at 45 °C for 6 h. After centrifugation to remove excess solution, the solution was vacuum dried for 12 h. Finally, the solid was ground to obtain polyacrylonitrile-stabilized high-voltage Li3InCl6 solid electrolyte.

[0035] In this embodiment, the high-voltage Li3InCl6 solid electrolyte was used as the experimental group, and the untreated Li3InCl6 electrolyte material without a flexible polyacrylonitrile artificial protective layer was used as the blank group. The composite cathodes were matched with the high-nickel ternary cathode Ni92 to obtain composite cathodes and assembled into all-solid-state batteries for electrochemical performance testing. Figure 3 The results showed that the rate performance of the experimental group was significantly better than that of the control group at a cutoff voltage of 4.3 V and a capacitance of 4 C (1C = 200 mAh g). -1 At a given rate, the experimental group achieved a discharge specific capacity of 186.6 mAh g. -1 The blank group had only 135.3 mAh g. -1 .

[0036] Example 4 This embodiment provides a stable high-voltage Li-type in-situ polyacrylonitrile flexible ion transport interface layer. 0.388 Ta 0.238 La 0.475 The preparation method of Cl3 solid electrolyte is as follows: Ethylene glycol monomethyl ether 2-cyanoacrylate was dissolved in anisole at a molar ratio of 1:50. After complete dissolution, a homogeneous precursor solution was formed. Subsequently, 10 g of solid electrolyte powder Li 0.388 Ta 0.238 La 0.475Cl3 was added to 50 mL of the precursor solution and agitated evenly. The solution was stirred at 300 rpm for 9 h at 30 ℃. Excess solution was removed by centrifugation and the solution was vacuum dried for 12 h. Finally, the solid was ground to obtain polyacrylonitrile-stabilized high-voltage Li. 0.388 Ta 0.238 La 0.475 Cl3 solid electrolyte.

[0037] Example 5 This embodiment provides a stable high-voltage Li2In in-situ polyacrylonitrile flexible ion transport interface layer. 0.333 Sc 0.333 The preparation method of Cl4 solid electrolyte is as follows: Ethyl isocyanate acrylate was dissolved in 1-chloro-2,2,2-trifluoroethyl difluoromethyl ether at a molar ratio of 1:75 to form a homogeneous precursor solution. Then, 10 g of solid electrolyte powder Li₂In was added. 0.333 Sc 0.333 Cl4 was added to 50 ml of the precursor solution and agitated evenly. The solution was stirred at 300 rpm for 12 h at 60 ℃. Excess solution was removed by centrifugation and the solution was vacuum dried for 12 h. Finally, the solid was ground to obtain polyacrylonitrile-stabilized high-voltage Li2In. 0.333 Sc 0.333 Cl4 solid electrolyte.

[0038] This embodiment uses the manufactured high-voltage Li2In 0.333 Sc 0.333 Cl4 solid electrolyte was used as the experimental group, with untreated Li2In without a flexible polyacrylonitrile artificial protective layer. 0.333 Sc 0.333 Cl4 solid electrolyte material was used as a blank group. Composite cathodes were obtained by matching them with high-nickel ternary cathode Ni94, and then assembled into all-solid-state batteries for electrochemical performance testing. For example... Figure 4 As shown, even under a high cutoff voltage of 4.5 V, compared to the blank group, 0.1 C (1 C = 200 mAh g) -1 At higher rates, the experimental group still achieved improved first-week capacity and first-week cycling coulombic efficiency, reaching as high as 237.9 mAh g⁻¹. -1 And 91.1%. Figure 5 It can be seen that the rate performance of the experimental group and the blank group at 4.5 V is significantly different. At a 2 C rate, the discharge specific capacity of the experimental group reaches as high as 222.4 mAhg. -1 The blank group had only 171.3 mAh g. -1 . Figure 6 and Figure 7The cycle capacity and coulombic efficiency of the experimental and control all-solid-state batteries at a high cutoff voltage of 4.5 V are shown. It can be observed that the experimental group has excellent high-voltage cycle performance, and the discharge specific capacity is maintained at 200 mAh g⁻¹. -1 The experimental group maintained a stable cycle coulombic efficiency of over 99.9%, while the control group only achieved around 99.6%. In conclusion, the polyacrylonitrile artificial ion transport layer, which also serves as a buffer and protective interface, can effectively improve the positive electrode charging voltage and enhance the rate performance and cycle life of lithium-ion solid-state batteries.

[0039] Example 6 This embodiment provides a method for preparing a high-voltage Li3YCl6 solid electrolyte with an in-situ polynitrile flexible ion transport interface layer, the steps of which are as follows: Isocyanoethyl methacrylate was dissolved in 1-chloro-2,2,2-trifluoroethyl difluoromethyl ether at a molar ratio of 1:100 to form a homogeneous precursor solution. Then, 10 g of solid electrolyte powder Li3YCl6 was added to 50 mL of the precursor solution and shaken uniformly. The solution was stirred at 300 rpm for 1 h at 30 ℃. After centrifugation to remove excess solution, the solution was vacuum dried for 12 h. Finally, the solid was ground to obtain polyacrylonitrile-stable high-voltage Li3YCl6 solid electrolyte.

[0040] Example 7 This embodiment provides a method for preparing a high-voltage Li3YCl6 solid electrolyte with an in-situ polynitrile flexible ion transport interface layer, the steps of which are as follows: 2-Cyano-2-butyl acrylate was dissolved in 2,2,2-trifluoroethyl ether at a molar ratio of 1:50 to form a homogeneous precursor solution. Then, 10 g of solid electrolyte powder Li3YCl6 was added to 50 mL of the precursor solution and shaken uniformly. The solution was stirred at 300 rpm for 3 h at 30 ℃. After centrifugation to remove excess solution, the solution was vacuum dried for 12 h. Finally, the solid was ground to obtain polyacrylonitrile-stable high-voltage Li3YCl6 solid electrolyte.

[0041] Example 8 This embodiment provides a stable high-voltage Li-type in-situ polyacrylonitrile flexible ion transport interface layer. 0.388 Ta 0.238 La 0.475 The preparation method of Cl3 solid electrolyte is as follows: Ethyl 2-cyano-3-ethoxyacrylate was dissolved in anisole at a molar ratio of 1:25 to form a homogeneous precursor solution. Then, 10 g of solid electrolyte powder Li... 0.388 Ta 0.238 La 0.475Cl3 was added to 50 mL of the precursor solution and agitated uniformly. The solution was stirred at 300 rpm for 6 h at 25 °C. Excess solution was removed by centrifugation and the solution was vacuum dried for 12 h. Finally, the solid was ground to obtain polyacrylonitrile-stabilized high-voltage Li. 0.388 Ta 0.238 La 0.475 Cl3 solid electrolyte.

[0042] Example 9 This embodiment provides a method for preparing a high-voltage Li₂ZrCl₆ solid electrolyte with an in-situ polynitrile flexible ion transport interface layer, the steps of which are as follows: Ethyl 2-cyano-3-ethoxycrotonic acid was dissolved in 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether at a molar ratio of 1:5 to form a homogeneous precursor solution. Then, 10 g of solid electrolyte powder Li2ZrCl6 was added to 50 mL of the precursor solution and shaken uniformly. The solution was stirred at 300 rpm for 9 h at 30 ℃. After centrifugation to remove excess solution, the solution was vacuum dried for 12 h. Finally, the solid was ground to obtain polyacrylonitrile-stable high-voltage Li2ZrCl6 solid electrolyte.

[0043] Example 10 This embodiment provides a method for preparing a high-voltage Li3InCl6 solid electrolyte with an in-situ stable polynitrile flexible ion transport interface layer. The steps are as follows: Methyl 2-cyano-3-phenylacrylate was dissolved in 1,2-dimethyltetrahydrofuran at a molar ratio of 1:1 to form a homogeneous precursor solution. Then, 10 g of solid electrolyte powder Li3InCl6 was added to 50 mL of the precursor solution and shaken uniformly. The solution was stirred at 300 rpm for 12 h at 30 ℃. After centrifugation to remove excess solution, the solution was vacuum dried for 12 h. Finally, the solid was ground to obtain polyacrylonitrile-stabilized high-voltage Li3InCl6 solid electrolyte.

[0044] This invention utilizes the in-situ polymerization reaction initiated by the electrophilic induction of nitrile monomers by multivalent central metal ions contained in a specific chloride solid electrolyte to form a uniform and complete polynitrile-based artificial organic flexible ionic conductor interface layer on the surface of the chloride solid electrolyte without damaging the crystal structure and ionic conductivity of the chloride solid electrolyte itself. This non-destructive interface layer can effectively enhance the electrochemical stability of the solid electrolyte and can be matched with high-voltage lithium-ion cathode materials. In addition, it can also enhance the air stability of the electrolyte and the mechanical stability of the electrode-electrolyte interface, significantly suppress the formation of porosity and electrode cracks at the interface, and improve the rate performance and cycle life of lithium-ion solid batteries.

[0045] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for preparing a high-voltage chloride solid electrolyte with an in-situ polyacrylonitrile flexible ion transport interface layer stabilized, characterized in that, Includes the following steps: A high-voltage solid chloride electrolyte is obtained by mixing a chloride solid electrolyte with a precursor solution containing nitrile monomers and using the metal central ion of the chloride solid electrolyte to initiate the in-situ polymerization reaction of the nitrile monomers, forming a polymer layer on the surface of the chloride solid electrolyte. The chloride solid electrolyte includes lithium indium chloride (Li3InCl6), lithium yttrium chloride (Li3YCl6), lithium zirconium chloride (Li2ZrCl6), and lithium indium scandium chloride (Li2In). 0.333 Sc 0.333 Cl4, lithium, tantalum, lanthanum, chlorine, Li 0.388 Ta 0.238 La 0.475 At least one of Cl3, or a variant of a chloride solid electrolyte obtained by transforming a multivalent central metal coordination ion.

2. The method for preparing a high-voltage chloride solid electrolyte with an in-situ stable polyacrylonitrile flexible ion transport interface layer according to claim 1, characterized in that: The nitrile monomers include at least one of the following: ethyl 2-cyanoacrylate, acrylonitrile, 2-ethyl cyanoacrylate, ethylene glycol monomethyl ether 2-cyanoacrylate, ethyl isocyanate, ethyl isocyanate methacrylate, butyl 2-cyano-2-acrylate, ethyl 2-cyano-3-ethoxyacrylate, ethyl 2-cyano-3-ethoxycrotonate, and methyl 2-cyano-3-phenylacrylate.

3. The method for preparing a high-voltage chloride solid electrolyte with an in-situ polyacrylonitrile flexible ion transport interface layer stable according to claim 1, characterized in that: The molar ratio of the chloride solid electrolyte to the nitrile monomer is 5~50:

1.

4. The method for preparing a high-voltage chloride solid electrolyte with an in-situ polyacrylonitrile flexible ion transport interface layer stable according to claim 1, characterized in that: The precursor solution is prepared by dissolving nitrile monomers in an ether solvent; the molar ratio of the ether solvent to the nitrile monomer is controlled to be 1~100:

1.

5. The method for preparing a high-voltage chloride solid electrolyte with an in-situ polyacrylonitrile flexible ion transport interface layer stable according to claim 4, characterized in that: The ether solvents include at least one of anisole, 2,2,2-trifluoroethyl ether, 1-chloro-2,2,2-trifluoroethyl difluoromethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, and 1,2-dimethyltetrahydrofuran.

6. The method for preparing a high-voltage chloride solid electrolyte with an in-situ polyacrylonitrile flexible ion transport interface layer stable according to claim 4, characterized in that: The in-situ polymerization reaction is carried out at a temperature of 20-60 °C for 1-12 h.

7. The method for preparing a high-voltage chloride solid electrolyte with an in-situ polyacrylonitrile flexible ion transport interface layer stable according to claim 1, characterized in that: After the in-situ polymerization reaction is completed, the product is further purified by washing and drying to obtain a high-voltage chloride solid electrolyte.

8. A high-voltage chloride solid electrolyte, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 7.

9. An application of the high-voltage chloride solid electrolyte as described in claim 8, characterized in that, This includes its use as a solid electrolyte in the preparation of full cells.

10. The application of the high-voltage chloride solid electrolyte according to claim 9, characterized in that: The positive electrode material of the full battery includes at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese iron phosphate, lithium-rich manganese-based materials, ternary lithium nickel cobalt manganese oxide, and ternary lithium nickel cobalt aluminum oxide; the negative electrode material includes at least one of lithium aluminum alloy, lithium indium alloy, silicon negative electrode, silicon carbon negative electrode, and lithium metal.

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