A single lithium ion-conducting polymer solid-state electrolyte, and a preparation method and applications thereof

Abstract

This invention belongs to the field of battery material technology, and provides a single-lithium-ion conductive polymer solid electrolyte, its preparation method, and its application. The single-lithium-ion conductive polymer solid electrolyte of this invention uses P... 1,101 TFSI / Li-Nafion@LLZTO was added as a filler to the matrix resin to promote the addition of cationic Li in the lithium salt. + The migration of lithium ions improves the efficiency of lithium ion transport, which is beneficial for enhancing the contact between the electrode and the interface. It also results in high ionic conductivity and lithium ion transference number (ionic conductivity can reach up to 2.31 × 10⁻⁶). ‑4 S cm ‑1 With an ion transference number of up to 0.63, it exhibits high electrode / electrolyte interface stability, which can reduce interface resistance and contribute to the practical application and high performance of lithium-ion batteries based on SLCP solid electrolyte.

Description

Technical Field

[0001] This invention relates to the field of battery materials technology, and more specifically, to a single lithium-ion conductive polymer solid electrolyte, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries, as a representative of high-performance and low-cost emerging secondary energy storage devices, have penetrated into all aspects of production and life, showing promising application prospects in electric vehicles, aerospace, and small electronic devices. However, during the deposition process of lithium anodes, dendrites are prone to form on the electrode surface, increasing the risk of battery short circuits and capacity reduction. This places higher demands on the overall stability of the battery. Current solid-state batteries use solid electrolytes instead of traditional organic electrolytes. Solid electrolytes have flame retardant properties that enhance safety, and their high mechanical strength helps to combat dendrite formation, thus solving the problems currently faced by lithium-ion batteries. Solid-state batteries are one of the most promising directions for the development of traditional lithium-ion batteries.

[0003] Solid-state electrolytes are generally classified into three types: inorganic ceramic electrolytes, organic polymer electrolytes, and organic-inorganic composite electrolytes that combine the two types. Among them, polymer electrolytes have advantages such as good flexibility, high electrode compatibility, and highly customizable structures. However, the ionic conductivity and lithium-ion transference number of traditional polymer solid-state electrolytes still need improvement. To address this issue, single lithium-ion conductive polymer (SLCP) solid-state electrolytes have emerged. SLCP solid-state electrolytes are a new type of solid-state electrolyte obtained by further modifying traditional polymer electrolytes, which can improve the difficulty of lithium-ion migration present in polymer electrolytes.

[0004] There are three strategies for preparing SLCP solid electrolytes: (1) introducing monoionic groups that can anchor anions into polymer chain segments through reaction during the preparation and synthesis of polymers; (2) inorganic framework type SLCP solid electrolytes are prepared by introducing anchoring groups into the surface of inorganic ceramic filler nanoparticles; (3) anion acceptor type electrolytes are prepared by adding organic molecular scavengers modified with monoionic groups to polymer solid electrolytes.

[0005] Although the ionic conductivity of the SLCP solid electrolyte prepared by the above method is generally 1.2*10⁻⁶, -4 S cm -1While there has been a significant improvement, SLCP solid electrolytes still lag far behind liquid electrolytes, insufficient to support practical applications. Furthermore, the insufficient stability of SLCP solid electrolytes at high current densities severely limits their application areas, falling far short of actual needs. SLCP solid electrolytes also suffer from numerous interface problems such as dendrite formation. In addition, due to the non-fluidity of solid electrolytes, the interfacial contact between them and electrodes is poor, and electrochemical reactions caused by the potential difference between the electrolyte and electrodes are extremely common in practical applications. High-capacity anode and cathode materials of SLCP solid electrolytes also exhibit compatibility issues.

[0006] Therefore, there is an urgent need to develop a single lithium-ion conductive polymer solid electrolyte with high ionic conductivity and lithium-ion transference number, high electrode / electrolyte interface stability, and reduced interface resistance. Summary of the Invention

[0007] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a single-lithium-ion conductive polymer solid electrolyte, its preparation method, and its application. The single-lithium-ion conductive polymer solid electrolyte provided by this invention has high ionic conductivity and lithium-ion transference number (ionic conductivity can reach up to 2.31 × 10⁻⁶). -4 S cm -1 With an ion transference number of up to 0.63, it exhibits high electrode / electrolyte interface stability, which can reduce interface resistance and contribute to the practical application and high performance of lithium-ion batteries based on SLCP solid electrolyte.

[0008] A first aspect of the present invention provides a single lithium-ion conductive polymer solid electrolyte.

[0009] Specifically, a single lithium-ion conductive polymer solid electrolyte comprises the following raw material components:

[0010] Filler and matrix resin; the filler is a polymer coated with lithium-ion perfluorosulfonic acid-polytetrafluoroethylene copolymer (lithium-ion polymer or Li-Nafion) and N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide (P 1,101 Conductive ceramic powder (TFSI ionic liquid).

[0011] This invention uses P 1,101 TFSI / Li-Nafion® conductive ceramic powder is added as a filler to the matrix resin. The molecular chains of the filler and the matrix resin can form a three-dimensional continuous spatial network in P... 1,101 The synergistic effect of TFSI / Li-Nafion and conductive ceramic powder enables the single-ion conductive polymer electrolyte to effectively immobilize anions, achieving efficient lithium-ion transport. In-situ coating of P on the surface of the conductive ceramic powder further facilitates this process.1,101 TFSI ionic liquids and pre-lithiated polymer Li-Nafion, with Li-Nafion primarily functioning to bind anions and effectively reduce Li- + The migration barrier promotes the migration of Li cations in lithium salts. + migration; P 1,101 TFSI and conductive ceramic powders possess the properties of high ionic conductivity and high mechanical strength, P 1,101 The addition of TFSI ionic liquid is beneficial to enhance the contact between the electrode and the interface, and improve the efficient transport of lithium ions; conductive ceramic powder as a filler in single-ion conductive polymer electrolyte can improve the mechanical strength of the electrolyte membrane and suppress lithium dendrite puncture.

[0012] Preferably, the conductive ceramic powder is tantalum-doped lithium lanthanum zirconium oxide powder (LLZTO) and / or lithium lanthanum zirconium oxide (Li7La3Zr2O). 12 (abbreviated as LLZO).

[0013] Preferably, the matrix resin is polyethylene oxide (PEO).

[0014] Preferably, the tantalum-doped lithium lanthanum zirconium oxide (LLZTO) powder has a particle size of 200-400 nm. Utilizing the physical dispersion characteristics of nanoscale LLZTO, not only can the carried P... 1,101 TFSI / Li-Nafion is placed within a conductive polymer electrolyte, achieving uniform dispersion within the electrolyte membrane and reducing Li in the situ. + Migration barrier, improving lithium-ion transport efficiency.

[0015] More preferably, the tantalum-doped lithium lanthanum zirconium oxide (LLZTO) powder has a particle size of 300-350 nm.

[0016] Preferably, the lithium-ion perfluorosulfonic acid-polytetrafluoroethylene copolymer (Li-Nafion) and N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imine salt (P 1,101 The mass ratio of TFSI ionic liquid and conductive ceramic powder is (4-6):(7-9):(1-3).

[0017] More preferably, the lithium-ion perfluorosulfonic acid-polytetrafluoroethylene copolymer (Li-Nafion), N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt (P 1,101 The mass ratio of TFSI ionic liquid and conductive ceramic powder is one of 5:8:2, 6:9:3, or 4:7:1.

[0018] Preferably, the mass ratio of the filler to the matrix resin is (0.5-0.8):1.

[0019] A second aspect of the present invention provides a method for preparing a single lithium-ion conductive polymer solid electrolyte.

[0020] A method for preparing a single lithium-ion conductive polymer solid electrolyte includes the following steps:

[0021] (1) Lithium-based perfluorosulfonic acid-polytetrafluoroethylene copolymer (lithium-based Nafion polymer) and N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt (P 1,101 The filler (P) is prepared by mixing TFSI ionic liquid, adding conductive ceramic powder, mixing and stirring, and drying. 1,101 TFSI / Li-Nafion@conductive ceramic powder);

[0022] (2) The filler and matrix resin are added to an organic solvent, mixed and stirred, cast onto a substrate, and vacuum dried to obtain the single lithium-ion conductive polymer solid electrolyte (PEO-P). 1,101 TFSI / Li-Nafion@conductive ceramic powder).

[0023] This invention uses Li-Nafion, P 1,101 Using TFSI ionic liquid as a raw material, the two are first mixed via a solution method, and then conductive ceramic powder is added. P is then uniformly and in-situ coated onto the surface of the conductive ceramic powder. 1,101 TFSI / Li-Nafion was used to prepare the filler, and then P was added. 1,101 TFSI / Li-Nafion@conductive ceramic powder was uniformly mixed as a composite filler and added to a solid polymer electrolyte to prepare a single-lithium-ion conductive polymer solid electrolyte. This method achieves P 1,101 TFSI / Li-Nafion@conductive ceramic powder exhibits good dispersion and compatibility with PEO. This invention introduces P into a solid electrolyte. 1,101 TFSI, Li-Nafion, and conductive ceramic powders can enhance the lithium-ion transport properties of solid-state electrolytes. 1,101 TFSI and conductive ceramic powders possess high ionic conductivity and mechanical strength, while Li-Nafion can effectively reduce Li... + Benefiting from these advantages, the single lithium-ion conductive polymer (SLCP) solid electrolyte exhibits excellent stability and long cycle life during constant current charge-discharge processes in lithium-ion batteries. Furthermore, the preparation process of this invention is simple, low-cost, and environmentally friendly, making it feasible for widespread application.

[0024] Preferably, in step (1), the mixture is stirred at 60-80°C for 12-24 hours.

[0025] Preferably, in step (1), the product is dried by blowing air at 60-80°C for 24-48 hours.

[0026] Preferably, in step (2), the organic solvent is acetonitrile and / or polyvinylpyrrolidone (NMP).

[0027] Preferably, in step (2), the mixture is stirred at 60-80°C for 12-24 hours.

[0028] Preferably, in step (2), the substrate is an expanded polytetrafluoroethylene (PTFE) plate.

[0029] Preferably, in step (2), the product is vacuum dried at 60-80°C for 12-24 hours.

[0030] Preferably, in step (1), the preparation method of the lithium perfluorosulfonic acid-polytetrafluoroethylene copolymer (Li-Nafion) includes the following steps: mixing LiOH and the perfluorosulfonic acid-polytetrafluoroethylene copolymer and adding them to an organic solvent, stirring at 60-80°C for 8-12 hours to obtain a lithium perfluorosulfonic acid-polytetrafluoroethylene copolymer (Li-Nafion) solution.

[0031] Preferably, the mass ratio of LiOH to perfluorosulfonic acid-polytetrafluoroethylene copolymer is (0.1-0.3):(10-20).

[0032] Preferably, the organic solvent is N,N-dimethylformamide (DMF).

[0033] Preferably, in step (1), the N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imine salt (P 1,101 The preparation method of TFSI ionic liquid includes the following steps: N-(methoxymethyl)-N-methylpyrrolidine halide (P... 1，101 X) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were mixed, dissolved in water, and then an organic solvent was added. The mixture was reacted, and after the reaction, the layers separated. The lower layer (a mixture of ionic liquid and organic solvent) was retained. Water was added to the lower layer, and the above steps were repeated until the upper layer (an aqueous layer) was obtained. No white precipitate was found when tested with silver nitrate. The lower layers were combined, dried, and recrystallized at ultra-low temperature. The mixture was dried again to obtain N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide (P). 1,101 TFSI ionic liquids).

[0034] Preferably, the N-(methoxymethyl)-N-methylpyrrolidine halide (P 1，101 X) is N-(methoxymethyl)-N-methylpyrrolidine bromide (P) 1，101 Br).

[0035] Preferably, the N-(methoxymethyl)-N-methylpyrrolidine halide (P 1，101 The mass ratio of X) to lithium bis(trifluoromethanesulfonylimide) is (1-2):(0.5-1).

[0036] Preferably, the organic solvent is dichloromethane.

[0037] Preferably, the reaction temperature is 20-35°C, and / or the reaction time is 30-60 min.

[0038] Preferably, the ultra-low temperature recrystallization includes the following steps: after drying, the crude product is mixed with an organic solvent (the organic solvent is selected from one or two of dichloromethane, ethanol, propanol, ethyl acetate, diethyl ether, and chloroform), and then transferred to an environment below 0°C (selected from one of -4°C, -30°C, and -80°C) for crystallization. The waste liquid is then poured off, and the above operation is repeated 2-3 times. The crystals are then warmed back to room temperature, and then rotary evaporated for 2-3 hours, followed by direct pumping for 8-10 hours for drying to obtain high-purity N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt (P 1,101 TFSI ionic liquids).

[0039] Low-temperature recrystallization refers to a method in which a crude product is mixed with a mixture of one or two organic solvents, and impurities in the crude product are separated and removed by repeated low-temperature crystallization. This method can effectively improve the purity of ionic liquids. Due to the synthesis of P... 1, 101 The crude TFSI ionic liquid contains a small amount of impurities that are difficult to salt out, which can be effectively purified by ultra-low temperature recrystallization.

[0040] A third aspect of the present invention provides an application of a single lithium-ion conductive polymer solid electrolyte.

[0041] Application of a single lithium-ion conductive polymer solid electrolyte in lithium-ion batteries.

[0042] A lithium-ion battery comprising the single lithium-ion conductive polymer solid electrolyte.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] The single lithium-ion conductive polymer solid electrolyte of this invention is mainly composed of fillers and matrix resin, with P 1, 101 TFSI / Li-Nafion@LLZTO was added as a filler to the matrix resin in P 1,101The synergistic effect of TFSI / Li-Nafion and LLZTO enables the single-ion conductive polymer solid electrolyte to effectively immobilize anions, achieving efficient lithium-ion transport and promoting the transfer of Li-cations in lithium salts. + The migration of lithium ions improves the efficiency of lithium ion transport, which is beneficial for enhancing the contact between the electrode and the interface. It also results in high ionic conductivity and lithium ion transference number (ionic conductivity can reach up to 2.31 × 10⁻⁶). -4 S cm -1 With an ion transference number of up to 0.63, it exhibits high electrode / electrolyte interface stability, which can reduce interface resistance and contribute to the practical application and high performance of lithium-ion batteries based on SLCP solid electrolyte. Attached Figure Description

[0045] Figure 1 The PEO-P prepared in Example 1 of this invention 1,101 LSV (linear sweep voltammetry) test curves of TFSI / Li-Nafion@LLZTO;

[0046] Figure 2 The PEO-P prepared in Example 1 of this invention 1,101 The results of the first three CV (cyclic voltammetry) cycles of TFSI / Li-Nafion@LLZTO;

[0047] Figure 3 The PEO-P prepared in Example 2 of this invention 1,101 Comparison of impedance spectra of TFSI / Li-Nafion@LLZTO before and after polarization;

[0048] Figure 4 The PEO-P prepared in Example 2 of this invention 1,101 Steady-state current curve of TFSI / Li-Nafion@LLZTO;

[0049] Figure 5 The PEO-P prepared in Example 3 of this invention 1,101 Ionic conductivity curves of TFSI / Li-Nafion@LLZTO. Detailed Implementation

[0050] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0051] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0052] The raw materials used in this invention are as follows:

[0053] Tantalum-doped lithium lanthanum zirconium oxide powder (LLZTO): purchased from Shenzhen Kejing Zhida Technology Co., Ltd., with a particle size of 300nm.

[0054] Example 1

[0055] A single lithium-ion conductive polymer solid electrolyte, comprising the following raw material components: filler (P 1,101 TFSI / Li-Nafion@LLZTO) and matrix resin PEO; the filler is a surface-coated lithium-ion perfluorosulfonic acid-polytetrafluoroethylene copolymer (Li-Nafion) and N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt (P 1,101 tantalum-doped lithium lanthanum zirconium oxide powder (LLZTO) for TFSI ionic liquid.

[0056] A method for preparing a single lithium-ion conductive polymer solid electrolyte includes the following steps:

[0057] (1) Preparation of P 1,101 TFSI ionic liquids

[0058] 1g of P 1，101 Br and 0.5 g of LiTFSI were mixed and dissolved in 10 mL of ultrapure water, then 5 mL of dichloromethane was added. The mixture was stirred at room temperature for 30 min. After the reaction, the layers separated, and the lower layer (the mixture of ionic liquid and dichloromethane) was retained. 10 mL of ultrapure water was added to the mixture of ionic liquid and dichloromethane, and the mixture was stirred and washed at room temperature for 10 min. After washing, the layers separated, and the lower layer (the mixture of ionic liquid and dichloromethane) was retained. The steps were repeated until no white precipitate was detected by silver nitrate, indicating that the reaction was complete. The mixture was then rotary evaporated and vacuum dried for about 8 h to obtain P. 1,101 TFSI ionic liquid.

[0059] (2) Preparation of Li-Nafion

[0060] 0.1 g of LiOH·H2O and 10 g of Nafion-H (perfluorosulfonic acid resin) powder were added to 10 mL of N,N-dimethylformamide (DMF) and stirred at 60 °C for 8 h to form a Li-Nafion solution.

[0061] (3) Preparation of PEO-P 1,101 TFSI / Li-Nafion@LLZTO single lithium-ion conductive polymer solid electrolyte membrane

[0062] Add 5 mL of P to the Li-Nafion solution prepared above. 1,101 TFSI ionic liquid, with the addition of LLZTO powder, Li-Nafion:P 1,101The mass ratio of TFSI ionic liquid to LLZTO was 0.5:0.8:0.2 g. The mixture was stirred at 60 °C for 12 h to ensure thorough mixing, and then dried at 60 °C for 24 h to obtain P. 1,101 TFSI / Li-Nafion@LLZTO powder. Then 5g of PEO powder was mixed with P 1,101 TFSI / Li-Nafion@LLZTO powder filler was added to 20 mL of acetonitrile solution, and the mixture was stirred at 60 °C for 12 h. It was then cast onto expanded PTFE plates and dried under vacuum at 60 °C for 12 h to finally obtain PEO-P. 1,101 TFSI / Li-Nafion@LLZTO single lithium-ion conductive polymer solid electrolyte membrane.

[0063] Example 2

[0064] A single lithium-ion conductive polymer solid electrolyte, comprising the following raw material components: filler (P 1,101 TFSI / Li-Nafion@LLZTO) and matrix resin PEO; the filler is a surface-coated lithium-ion perfluorosulfonic acid-polytetrafluoroethylene copolymer (Li-Nafion) and N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt (P 1,101 tantalum-doped lithium lanthanum zirconium oxide powder (LLZTO) for TFSI ionic liquid.

[0065] A method for preparing a single lithium-ion conductive polymer solid electrolyte includes the following steps:

[0066] (1) Preparation of P 1,101 TFSI ionic liquids

[0067] 2g P 1,101 Br and 1g LiTFSI were mixed and dissolved in 50mL of ultrapure water, then 10mL of dichloromethane was added. The mixture was stirred at room temperature for 60min. After the reaction, the layers separated, and the lower layer of ionic liquid and dichloromethane mixture was retained. 50mL of ultrapure water was added to the ionic liquid and dichloromethane mixture, and the mixture was stirred and washed at room temperature for 20min. After washing, the layers separated, and the lower layer of ionic liquid and dichloromethane mixture was retained. The steps were repeated until no white precipitate was detected by silver nitrate, indicating that the reaction was complete. The mixture was then rotary evaporated and vacuum dried for about 12h to obtain P. 1,101 TFSI ionic liquid.

[0068] (2) Preparation of Li-Nafion solution

[0069] 0.3 g of LiOH·H2O and 20 g of Nafio-H powder were added to 20 mL of N,N-dimethylformamide (DMF) and stirred at 80 °C for 12 h to form a Li-Nafion solution.

[0070] (3) Preparation of PEO-P 1,101 TFSI / Li-Nafion@LLZTO single lithium-ion conductive polymer solid electrolyte

[0071] Add 10 mL of P to the Li-Nafion solution prepared above. 1,101 TFSI ionic liquid, with the addition of LLZTO powder, Li-Nafion:P 1,101 The mass ratio of TFSI ionic liquid to LLZTO was 0.6 g: 0.9 g: 0.3 g. The mixture was stirred at 80 °C for 24 h to ensure thorough mixing, and then dried at 80 °C for 48 h to obtain P. 1,101 TFSI / Li-Nafion@LLZTO powder. Mix 10g of PEO powder with P... 1,101 TFSI / Li-Nafion@LLZTO filler was added to 30 mL of acetonitrile solution, and the mixture was stirred at 80 °C for 24 h. It was then cast onto expanded PTFE plates and dried under vacuum at 80 °C for 24 h to finally obtain PEO-P. 1,101 TFSI / Li-Nafion@LLZTO single lithium-ion conductive polymer solid electrolyte.

[0072] Example 3

[0073] A single lithium-ion conductive polymer solid electrolyte, comprising the following raw material components: filler (P 1,101 TFSI / Li-Nafion@LLZTO) and matrix resin PEO; the filler is a surface-coated lithium-ion perfluorosulfonic acid-polytetrafluoroethylene copolymer (Li-Nafion) and N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt (P 1,101 tantalum-doped lithium lanthanum zirconium oxide powder (LLZTO) for TFSI ionic liquid.

[0074] A method for preparing a single lithium-ion conductive polymer solid electrolyte includes the following steps:

[0075] (1) Preparation of P 1,101 TFSI ionic liquids

[0076] 1.5g of P 1,101Br and 0.8 g of LiTFSI were mixed and dissolved in 30 mL of ultrapure water, then 8 mL of dichloromethane was added. The mixture was stirred at room temperature for 50 min. After the reaction, the layers separated, and the lower layer of ionic liquid and dichloromethane mixture was retained. 20 mL of ultrapure water was added to the ionic liquid and dichloromethane mixture, and the mixture was stirred and washed at room temperature for 15 min. After washing, the layers separated, and the lower layer of ionic liquid and dichloromethane mixture was retained. The steps were repeated until no white precipitate was detected by silver nitrate, indicating that the reaction was complete. The mixture was then rotary evaporated and vacuum dried for about 10 h to obtain P. 1,101 TFSI ionic liquid.

[0077] (2) Preparation of Li-Nafion solution

[0078] 0.2 g of LiOH·H2O and 15 g of Nafio-H powder were added to 15 mL of N,N-dimethylformamide (DMF) and stirred at 70 °C for 10 h to form a Li-Nafion solution.

[0079] (3) Preparation of single lithium-ion conductive polymer solid electrolyte

[0080] Add 8 mL of P to the Li-Nafion solution prepared above. 1,101 TFSI ionic liquid, with the addition of LLZTO powder, Li-Nafion:P 1,101 The mass ratio of TFSI ionic liquid to LLZTO was 0.4 g: 0.7 g: 0.1 g. The mixture was stirred at 70 °C for 15 h to ensure thorough mixing, and then dried at 70 °C for 32 h to obtain P. 1,101 TFSI / Li-Nafion@LLZTO powder. Mix 8g of PEO powder with P... 1,101 TFSI / Li-Nafion@LLZTO filler was added to 40 mL of acetonitrile solution, and the mixture was stirred at 70 °C for 20 h, then cast onto expanded PTFE plates. The mixture was then dried under vacuum at 70 °C for 20 h to finally obtain PEO-P. 1,101 TFSI / Li-Nafion@LLZTO single lithium-ion conductive polymer solid electrolyte.

[0081] Comparative Example 1

[0082] This comparative example provides a single lithium-ion conductive polymer solid electrolyte, which differs from Example 1 in that Li-Nafion is replaced with lithium hexafluorophosphate.

[0083] Lithium hexafluorophosphate (LiPF6) and Li-Nafion are fundamentally different. LiPF6 is an inorganic lithium salt, while Li-Nafion is an organic polymer. The main function of Li-Nafion is to bind anions and promote the formation of Li-cations in the lithium salt. +The migration of inorganic lithium salts is not possible, while inorganic lithium salts cannot play this role.

[0084] Comparative Example 2

[0085] This comparative example provides a single lithium-ion conductive polymer solid electrolyte, which differs from Example 1 in that P... 1,101 The TFSI ionic liquid was replaced with 1-ethyl-3-methylimidazolium tetrafluoroborate.

[0086] Comparative Example 3

[0087] This comparative example provides a single lithium-ion conductive polymer solid electrolyte, which differs from Example 1 in that the preparation method is different, as detailed below:

[0088] The obtained P 1,101 TFSI, Li-Nafion, and LLZTO were directly added to an acetonitrile solution containing PEO, and then an electrolyte membrane was prepared.

[0089] The method in Comparative Example 3 could not form P on the LLZTO surface. 1,101 The TFSI / Li-Nafion coating cannot effectively and uniformly disperse the single-ion conductive polymer P 1,101 TFSI / Li-Nafion affects ionic conductivity.

[0090] Application examples

[0091] CR2025 coin batteries (Li|GPE|LiNi) were fabricated using the single lithium-ion conductive polymer solid electrolyte (GPE) prepared in the above embodiments and comparative examples. 0.5 Co 0.2 Mn 0.3 O2 (NCM523) battery), in which the positive electrode material is LiNi 0.5 Co 0.2 Mn 0.3 The weight ratio of O2 (NCM523), Super P (conductive carbon black, conductive agent), and PVDF (polyvinylidene fluoride) is 8:1:1. The positive electrode loading is approximately 1 mg cm⁻¹. –2 All batteries were assembled in an argon-filled glove box. The assembled coin batteries were then subjected to electrochemical performance testing.

[0092] Figure 1 PEO-P as in Example 1 1,101 The LSV (linear sweep voltammetry) test curves of TFSI / Li-Nafion@LLZTO show that PEO-P 1,101 The TFSI / Li-Nafion@LLZTO single-lithium-ion conductive polymer solid electrolyte exhibits an oxidation potential as high as 4.4V. Among these... Figure 1In this context, Potential refers to electric potential, and Current refers to electric current.

[0093] Figure 2 PEO-P as in Example 1 1,101 The graph shows the results of the first three CV (cyclic voltammetry) cycles of the TFSI / Li-Nafion@LLZTO. As can be seen from the graph, the current density decreases continuously with the increase of the CV cycle number, indicating that the PEO-P... 1,101 The TFSI / Li-Nafion@LLZTO single-lithium-ion conductive polymer helps enhance the stability of the electrode-electrolyte interface. The single-lithium-ion conductive polymer solid electrolytes of Examples 2-3 also contribute to enhancing the stability of the electrode-electrolyte interface. Figure 2 In this context, Current density refers to the current density, and Potential refers to the electric potential.

[0094] Figure 3 PEO-P in Example 2 1,101 The impedance spectra of TFSI / Li-Nafion@LLZTO before and after polarization are compared. The impedance after polarization is higher than that before polarization, indicating that an SEI film (solid electrolyte film) is formed on the electrode surface after polarization, which leads to the increase in impedance.

[0095] Figure 4 PEO-P in Example 2 1,101 Steady-state current curve of TFSI / Li-Nafion@LLZTO, current potential 10mV. Combining impedance and steady-state current analysis before and after polarization, it can be seen that PEO-P... 1,101 The TFSI / Li-Nafion@LLZTO single-ion conductive polymer exhibits an ion transference number as high as 0.63, and the single-lithium-ion conductive polymer solid electrolytes of Examples 1 and 3 also possess high lithium-ion transference numbers. Figure 4 In this context, Time represents time and Current represents current.

[0096] Figure 5 PEO-P as in Example 3 1,101 Ionic conductivity curves of TFSI / Li-Nafion@LLZTO. Calculations show that PEO-P... 1,101 The ionic conductivity of TFSI / Li-Nafion@LLZTO is as high as 2.31 × 10⁻⁶. -4 S cm -1 The single lithium-ion conductive polymer solid electrolytes of Examples 1-2 also achieve high ionic conductivity.

Claims

1. A single lithium-ion conductive polymer solid electrolyte, characterized in that, It includes the following raw material components: Filler and matrix resin; the filler is a conductive ceramic powder with a surface coated with lithium-ion perfluorosulfonic acid-polytetrafluoroethylene copolymer and N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt; The single lithium-ion conductive polymer solid electrolyte is prepared by a method including the following steps: (1) The filler is prepared by mixing lithium perfluorosulfonic acid-polytetrafluoroethylene copolymer and N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, adding conductive ceramic powder, mixing and stirring, and drying. (2) The filler and matrix resin are added to an organic solvent, mixed and stirred, cast onto a substrate, and vacuum dried to obtain the single lithium-ion conductive polymer solid electrolyte.

2. The single lithium-ion conductive polymer solid electrolyte according to claim 1, characterized in that, The conductive ceramic powder is tantalum-doped lithium lanthanum zirconium oxide powder and / or lithium lanthanum zirconium oxide powder.

3. The single lithium-ion conductive polymer solid electrolyte according to claim 1, characterized in that, The matrix resin is polyethylene oxide.

4. The single lithium-ion conductive polymer solid electrolyte according to claim 1, characterized in that, The mass ratio of the lithium-ionized perfluorosulfonic acid-polytetrafluoroethylene copolymer, N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, and conductive ceramic powder is (4-6):(7-9):(1-3).

5. The single lithium-ion conductive polymer solid electrolyte according to claim 1, characterized in that, The mass ratio of the filler to the matrix resin is (0.5-0.8):

1.

6. A method for preparing a single lithium-ion conductive polymer solid electrolyte, wherein the single lithium-ion conductive polymer solid electrolyte according to any one of claims 1-5 is obtained by using the method.

7. The preparation method according to claim 6, characterized in that, In step (1), the preparation method of the lithium perfluorosulfonic acid-polytetrafluoroethylene copolymer includes the following steps: LiOH and perfluorosulfonic acid-polytetrafluoroethylene copolymer are mixed and added to an organic solvent, and stirred at 60-80℃ for 8-12h to obtain lithium perfluorosulfonic acid-polytetrafluoroethylene copolymer.

8. The preparation method according to claim 6, characterized in that, In step (1), the preparation method of N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt includes the following steps: N-(methoxymethyl)-N-methylpyrrolidine halide and lithium bis(trifluoromethanesulfonyl)imide are mixed, dissolved in water, and then an organic solvent is added. After the reaction is completed, the layers are separated, the lower liquid is retained, and water is added to the lower liquid. The above steps are repeated until no white precipitate is detected by silver nitrate in the upper liquid. The lower liquids are combined, dried, recrystallized at ultra-low temperature, and dried again to obtain N-(methoxymethyl)-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt.

9. The application of the single lithium-ion conductive polymer solid electrolyte according to any one of claims 1-5 in lithium-ion batteries.

10. A lithium-ion battery comprising the single lithium-ion conductive polymer solid electrolyte as described in any one of claims 1-5.

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