Two-dimensional material-based composite solid electrolyte with vertical arrangement structure and preparation method of two-dimensional material-based composite solid electrolyte

Abstract

The invention discloses a two-dimensional material-based composite solid electrolyte with a vertical arrangement structure and a preparation method of the two-dimensional material-based composite solid electrolyte. The preparation method comprises the following steps: preparing a two-dimensional material film by adopting dispersion liquid of two-dimensional nanosheets; polymer-containing slurry is prepared from a polymer, a lithium salt and the two-dimensional nanosheet; alternately carrying out spin coating of the slurry containing the polymer and pasting of the two-dimensional material film for several times to obtain a block body in which the polymer-containing film and the two-dimensional material film are alternately arranged for several layers; and carrying out at least drying, cold pressing and slicing on the block to obtain the two-dimensional material-based composite solid electrolyte with the vertical arrangement structure. The composite solid electrolyte has the advantages of high ionic conductivity at room temperature, wide electrochemical stability window, excellent air stability, excellent performance in a wide temperature range and the like.

Description

Technical Field

[0001] This invention relates to a two-dimensional material-based composite solid electrolyte with a vertically aligned structure and its preparation method, belonging to the field of solid electrolyte technology. Background Technology

[0002] Sulfide electrolytes are widely used in solid-state electrolytes due to their high ionic conductivity and excellent mechanical properties at room temperature. However, their poor electrochemical stability and narrow electrochemical stability window make them difficult to match with lithium metal anodes and high-voltage cathodes. Sulfide electrolytes also suffer from poor air stability and often require significant pressure during battery assembly, limiting their industrial application. Polyethylene oxide (PEO) has been extensively studied due to its low cost and simple preparation process, but its low ionic conductivity and poor mechanical properties at room temperature limit its industrial application.

[0003] Currently, research is being conducted on combining sulfides and polyethylene oxide to form composite solid electrolytes, aiming to leverage the advantages of each while mitigating their disadvantages. The goal is to achieve composite solid electrolytes that simultaneously possess high ionic conductivity at room temperature, a wide electrochemical stability window, and excellent mechanical properties. However, it is currently difficult for reported composite solid electrolytes to achieve a conductivity ≥10 at room temperature. - 3 Scm -1 It has a wide electrochemical stability window, excellent air stability, and superior performance over a wide temperature range.

[0004] Li-Zhen Fan et al. prepared an ultrathin, flexible composite solid electrolyte by combining Li6PS5Cl (LPSCL) with polyethylene-vinyl acetate (PEVA) and polytetrafluoroethylene (PTFE), which exhibited excellent ionic conductivity. However, due to the poor air stability of sulfides, the preparation process required argon protection, which restricted its large-scale industrial production (Li D, Liu H, Wang C, et al. High Ionic Conductive, Mechanical Robust Sulfide Solid Electrolyte Films and Interface Design for All-Solid-State Lithium Metal Batteries[J]. Advanced Functional Materials, 2024:2315555.).

[0005] Ming-Sheng Wang et al. prepared a composite solid electrolyte by combining amphoteric nanofibers with polyethylene oxide, which exhibited an ionic conductivity of 5.37 × 10⁻⁶ at room temperature. -4S cm -1 However, the half-cells and full-cells prepared by this composite solid electrolyte need to be tested at 60°C, which limits its industrial application (Cheng Y, Cai Z, Xu J, et al. Zwitterioniccellulose-based polymer electrolyte enabled by aqueous solution casting for high-performance solid-state batteries[J].Angewandte Chemie,2024,136(30):e202400477.).

[0006] Yunhui Huang et al., two-dimensional Li + conductor Li 0.46 Mn 0.77 PS3 is added to polyethylene oxide and stirred, then the organic solvent in the slurry is removed to form a composite solid electrolyte. Some two-dimensional materials lie flat in the polyethylene oxide under the influence of gravity. Assembled half-cells and full-cells require testing at 45°C, limiting their industrial application (Jiang B, Li F, Hou T, et al. Polymer electrolytes shielded by 2D Li). 0.46 Mn 0.77 PS3 Li+-conductors for all-solid-state lithium-metal batteries[J]. Energy Storage Materials, 2023, 56: 183-191.).

[0007] Shubin Yang et al. prepared a two-dimensional (2D) high-entropy lithium-ion conductor containing lithium transition metal phosphorus sulfide Li. x (Fe 1 / 5 Co 1 / 5 Ni 1 / 5 Mn 1 / 5 Zn 1 / 5 PS3, Li x (Fe 1 / 5 Co 1 / 5 Ni 1 / 5 Mn 1 / 5 Zn 1 / 5 PS3 was dispersed in nitrile butadiene rubber (NBR), and then the two-dimensional material was allowed to lie flat in the NBR by vacuum filtration. Its ionic conductivity was 5 × 10⁻⁶. -4 Scm -1 It did not reach a value greater than 1×10-3 Scm -1 Restricting its industrial application (Zhao Q, Cao Z, Wang, XingguoChen, HaoShi, YuCheng, ZongjuGuo, YuLi, BinGong, YongjiDu, ZhiguoYang, Shubin. High-EntropyLaminates with High Ion Conductivities for High-Power All-Solid-State LithiumMetal Batteries[J]. Journal of the American Chemical Society,2023,145(39):21242-21252.).

[0008] In the aforementioned composite solid electrolytes, the fillers were dispersed in the polymer by mechanical stirring. However, in the study of composite solid electrolytes using two-dimensional sulfides as fillers, the advantages of both polymers and two-dimensional sulfides were not fully utilized due to the low content of two-dimensional sulfides, the disordered distribution and orientation of the fillers, and the lack of directional fast channels for ion transport. The prepared solid electrolytes could not simultaneously possess the advantages of high ionic conductivity at room temperature, wide electrochemical stability window, excellent air stability, and excellent performance over a wide temperature range. Summary of the Invention

[0009] To address the aforementioned technical problems, the present invention aims to provide a two-dimensional material-based composite solid electrolyte with a vertically aligned structure and its preparation method. The composite solid electrolyte of the present invention simultaneously possesses advantages such as high ionic conductivity at room temperature, a wide electrochemical stability window, excellent air stability, and superior performance over a wide temperature range.

[0010] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a two-dimensional material-based composite solid electrolyte with a vertically aligned structure, comprising the following steps:

[0011] (1) Two-dimensional material films were prepared using a dispersion of two-dimensional nanosheets;

[0012] (2) The polymer, lithium salt and two-dimensional nanosheets are dispersed in an organic solvent to obtain a polymer-containing slurry;

[0013] (3) Spin-coating the polymer-containing slurry onto a substrate and then heating it to obtain a first polymer-containing film; attaching one side of the two-dimensional material film to the first polymer-containing film and applying pressure to obtain a composite structure of a polymer-containing film and a two-dimensional material film.

[0014] (4) Spin-coating the polymer-containing slurry onto the surface of the two-dimensional material film of the composite structure, and then heating it to obtain a second polymer-containing film; then pasting one side of the two-dimensional material film onto the second polymer-containing film and applying pressure; alternating spin-coating of the polymer-containing slurry and pasting of the two-dimensional material film several times to obtain a block with several layers of polymer-containing film and two-dimensional material film arranged alternately;

[0015] (5) The block is dried, cold-pressed and sliced ​​at least to obtain the two-dimensional material-based composite solid electrolyte with vertically arranged structure.

[0016] According to a specific embodiment of the present invention, preferably, the two-dimensional nanosheet has an ionic conductivity >1×10⁻⁶ under conditions of room temperature (23±2℃) and relative humidity RH<50%. -6 S cm -1 Two-dimensional materials. The method for testing ionic conductivity includes the following steps: the two-dimensional material film prepared by step (1) of the present invention is cut into rectangles and suspended above a square hole; both sides of the two-dimensional material film are attached to platinum wires; impedance measurement is performed using an electrochemical workstation with an adjustable frequency of 20Hz to 1MHz and an AC potential of 100mV; and ionic conductivity is tested in a constant temperature and humidity chamber.

[0017] According to a specific embodiment of the present invention, preferably, the two-dimensional nanosheet comprises, but is not limited to, one or more compounds represented by the following formula (i):

[0018] Li x M y PS3 style (i)

[0019] Where M includes one or more of Cd, Mn, Fe, Co, Ni, Zn and Cr, y is a number from 0.5 to 1, and x = 2 × (1 - y).

[0020] According to a specific embodiment of the present invention, preferably, the two-dimensional nanosheets include Li 0.46 Mn 0.77 PS3 and Li 0.3 Cd 0.85 One or two of the following: PS3, etc.

[0021] According to a specific embodiment of the present invention, preferably, the average thickness of the two-dimensional nanosheet is 0.6 to 10 nm, and the average lateral dimension is 0.1 to 10 μm.

[0022] According to a specific embodiment of the present invention, preferably, step (1) specifically includes: vacuum filtration of the dispersion of two-dimensional nanosheets, wherein the core diameter of the vacuum filtration device is 1-10 cm, the vacuum filtration adopts an aqueous microporous filter membrane with a pore size of 0.1-1 μm and a diameter of 2-1000 cm, and the filtration is carried out under a vacuum of 0.001-0.1 MPa for 1-1000 min (until the formed film has no obvious moisture), and then vacuum dried at 60-100°C for 1-20 h to obtain the two-dimensional material film.

[0023] According to a specific embodiment of the present invention, preferably, the concentration of the two-dimensional nanosheets in the dispersion of the two-dimensional nanosheets is 0.001 to 0.02 g / mL.

[0024] By controlling the concentration of nanosheets in the dispersion within the aforementioned range, this invention enables the layer-by-layer assembly of nanosheets after vacuum filtration under conditions controlled by this invention, forming a self-supporting two-dimensional material film with high nanosheet orientation.

[0025] According to a specific embodiment of the present invention, preferably, the preparation steps of the dispersion of the two-dimensional nanosheets include: (a) preparing MPS3 single crystals using chemical vapor transport method, wherein M includes one or more of Cd, Mn, Fe, Co, Ni, Zn, and Cr; (b) placing the MPS3 single crystals in a mixed solution containing potassium salt and selectively containing ethylenediaminetetraacetic acid for a first ion exchange intercalation reaction, wherein the potassium salt is preferably KCl and / or K2CO3, the concentration of the potassium salt in the mixed solution is preferably 1-3 mol / L, and when ethylenediaminetetraacetic acid is present, its concentration is preferably 1-3 mol / L, the content of the MPS3 single crystals in the mixed solution is preferably 0.005-0.015 g / mL, the temperature of the first ion exchange intercalation reaction is preferably 60-200℃, and the time is preferably 1-20 h. After the reaction, the product is washed to obtain K x M y PS3 block; (c) the K x M y The PS3 block is placed in an aqueous solution containing lithium salt for a second ion exchange intercalation reaction. The lithium salt is preferably LiCl, and the concentration of the lithium salt in the aqueous solution is preferably 1–3 mol / L. The K... x M y The preferred content of PS3 bulk in the lithium-containing aqueous solution is 0.005–0.015 g / mL. The preferred temperature for the second ion exchange intercalation reaction is 60–200 °C, and the preferred time is 1–20 h. After the reaction, the product is washed to obtain Li. x M y PS3 block; (d) the Lix M y PS3 blocks are placed in deionized water, subjected to ultrasonic treatment for peeling, and then centrifuged. The ultrasonic treatment power is preferably 100-200W, and the time is preferably 10-30 min. The centrifugation rate is preferably 2000-10000 rpm, and the time is preferably 5-20 min, yielding a dispersion of lithium transition metal phosphorus sulfide two-dimensional nanosheets. The nanosheets in the dispersion are mainly monolayer nanosheets. As mentioned above, this invention controls the concentration of nanosheets in the dispersion containing two-dimensional nanosheets. Therefore, if the concentration of the prepared two-dimensional nanosheet dispersion does not meet the above range, water can be added and / or some water removed to bring the concentration within the above range.

[0026] As described above, the two-dimensional nanosheets of the present invention are not limited to the lithium transition metal phosphorus sulfide two-dimensional nanosheets mentioned above, and may also be composed of other ions (Na+). + K + Zn 2+ Two-dimensional nanosheets of conductors (etc.).

[0027] According to a specific embodiment of the present invention, preferably, the thickness of the two-dimensional material film is 10 to 50 μm.

[0028] According to a specific embodiment of the present invention, preferably, in the two-dimensional material film, the number of nanosheets arranged along the planar direction and its parallel direction accounts for more than 60% of the total number of nanosheets. The nanosheets in the self-supporting two-dimensional material film of the present invention have the advantage of high orientation.

[0029] According to a specific embodiment of the present invention, preferably, the polymer includes one or more of polyethylene oxide (PEO), polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, polypropylene oxide, and polyvinylidene chloride.

[0030] According to a specific embodiment of the present invention, preferably, the lithium salt includes one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium oxide, lithium fluoride, lithium bis(fluorosulfonyl)imide, lithium nitride, lithium nitrate, and lithium hexafluorophosphate.

[0031] According to a specific embodiment of the present invention, preferably, the mass ratio of the polymer, the lithium salt, and the two-dimensional nanosheets is 1:01-0.4:0.01-0.15. The two-dimensional nanosheets used in step (2) can be prepared by first obtaining a dispersion of two-dimensional nanosheets using the method described above, and then by conventional steps such as drying.

[0032] According to a specific embodiment of the present invention, preferably, the content of the polymer in the organic solvent is 0.05 to 0.08 g / mL.

[0033] According to a specific embodiment of the present invention, preferably, the organic solvent includes one or more of acetonitrile, acetone, N,N-dimethylformamide and N-methylpyrrolidone.

[0034] According to a specific embodiment of the present invention, preferably, the spin coating speed of the polymer-containing slurry is 10–3000 r / min, the time is 10–600 s, and the temperature is -30–200°C. More preferably, the spin coating speed of the polymer-containing slurry is 100–1000 r / min, the time is 30–120 s, and the temperature is 25–60°C. The present invention, by controlling the polymer content in the polymer-containing slurry and controlling the spin coating speed, time, and temperature, achieves a smooth surface and a suitable and controllable thickness for the polymer-containing film.

[0035] According to a specific embodiment of the present invention, preferably, the heating temperature after spin-coating the polymer-containing slurry is 60–100°C, and the time is 30–120 seconds. The purpose of the heating is mainly to remove some of the solvent.

[0036] According to a specific embodiment of the present invention, preferably, the thickness of the polymer-containing film is 10 to 50 μm.

[0037] According to a specific embodiment of the present invention, preferably, one side of the two-dimensional material film is adhered to the polymer-containing film and a pressure of 0.1 to 200 MPa is applied. Those skilled in the art will understand that the direction of the applied pressure is in-plane towards the two-dimensional material film and perpendicular to the plane of the two-dimensional material film. More preferably, the applied pressure is 20 to 50 MPa.

[0038] According to a specific embodiment of the present invention, preferably, the number and width of the polymer-containing thin film and the two-dimensional material thin film in the block with alternating layers of polymer-containing thin film and two-dimensional material thin film are determined according to the area of ​​the composite solid electrolyte to be prepared.

[0039] According to a specific embodiment of the present invention, preferably, the conditions for drying the block include: vacuum drying at 60-100°C for 1-24 hours.

[0040] In this invention, the drying process of a block of alternating layers of polymer-containing film and two-dimensional material film allows the polymer to expand upon heating, preventing gaps between the polymer-containing film and the two-dimensional material film. It also removes residual solvents and, combined with the aforementioned pressure application, ensures tight, seamless contact between the polymer-containing film and the two-dimensional material film, thereby improving the performance of the composite solid electrolyte.

[0041] According to a specific embodiment of the present invention, preferably, the pressure of the cold pressing is 0.1 to 200 MPa, and the pressure holding time is 5 to 60 s.

[0042] According to a specific embodiment of the present invention, preferably, steps (1), (3), (4), and (5) are all performed in the presence of air. Step (2) (i.e., the preparation of the polymer-containing slurry) can be performed in a glove box or in the presence of air. The preparation process of the composite solid electrolyte of the present invention can all be performed in the presence of air, without the need for strict protection under a protective atmosphere. The composite solid electrolyte of the present invention has good air stability. This is because the preparation process of the two-dimensional nanosheets of the present invention is performed in the presence of water and air, which gives the two-dimensional nanosheets of the present invention good air stability, unlike traditional sulfides such as LiGePS and LiPSCl, which are prepared by ball milling under argon protection. All processes are performed in a glove box, and exposing them to air for a period of time will lead to a significant decrease in performance.

[0043] According to a specific embodiment of the present invention, preferably, step (5) further includes, after the cold pressing, storing the cold-pressed product in a glove box.

[0044] According to a specific embodiment of the present invention, preferably, the slice is made using a cryostat, the cryostat is set at a temperature of -30 to -1°C, and the angle of the slice is 30 to 90° with respect to the plane direction of the polymer-containing film and the two-dimensional material film, more preferably 45 to 90°.

[0045] The second aspect of the present invention provides a two-dimensional material-based composite solid electrolyte with a vertically aligned structure, which is prepared by the above-described method for preparing a two-dimensional material-based composite solid electrolyte with a vertically aligned structure.

[0046] According to a specific embodiment of the present invention, preferably, the thickness of the two-dimensional material-based composite solid electrolyte with a vertically aligned structure is 10–1000 μm. The present invention does not impose special limitations on the shape and planar dimensions of the two-dimensional material-based composite solid electrolyte with a vertically aligned structure; it can be designed according to the usage conditions, and its planar dimensions can be, for example, 0.1 cm. 2 ~1m2 It should be noted that the thickness of the composite solid electrolyte of the present invention is the thickness of the sheet electrolyte after slicing, and therefore the thickness depends on the settings of the slicer.

[0047] According to a specific embodiment of the present invention, preferably, based on 100% of the total mass of the two-dimensional material-based composite solid electrolyte with a vertically aligned structure, the content of the two-dimensional material film is 5-95%, and the content of the polymer-containing film is 5-95%. More preferably, based on 100% of the total mass of the two-dimensional material-based composite solid electrolyte with a vertically aligned structure, the content of the two-dimensional material film is 20-50%, and the content of the polymer-containing film is 50-80%.

[0048] In this invention, by controlling the content, thickness, and slicing angle of the two-dimensional material film and the polymer-containing film in the composite solid electrolyte within the above-mentioned range, the composite solid electrolyte achieves excellent performance.

[0049] The present invention has at least the following beneficial effects:

[0050] The preparation method of the two-dimensional material-based composite solid electrolyte with a vertically aligned structure of the present invention is simple and controllable, and can flexibly prepare composite solid electrolytes of different thicknesses and areas. Furthermore, the composite solid electrolyte prepared by the method of the present invention has a structure in which polymer-containing films and two-dimensional material films are alternately arranged, and the two-dimensional materials exhibit a vertically aligned structure within the surface of the composite solid electrolyte; moreover, the two-dimensional material films are continuous and penetrate the entire composite solid electrolyte; within the two-dimensional material films, the two-dimensional nanosheets are continuous, providing a continuous orientation structure conducive to ion conduction; simultaneously, the polymer-containing films of the present invention also contain two-dimensional nanosheets, and ion transport channels can be formed between the polymer-containing films and the two-dimensional material films. The present invention leverages the anisotropy of ion transport in two-dimensional materials to enable Li... + Continuous transport along the plane of a two-dimensional material (Li + (Lowest transmission energy barrier), shorten the transmission path, and avoid Li + The transmission is discontinuous. Furthermore, by controlling the preparation method, content, and thickness of the two-dimensional material film and the polymer-containing film, this invention ensures the continuity and uniform distribution of the two-dimensional material film and the polymer-containing film, further improving the performance of the composite solid electrolyte. The composite solid electrolyte of this invention simultaneously possesses advantages such as high ionic conductivity at room temperature, a wide electrochemical stability window, excellent air stability, and superior performance over a wide temperature range. Attached Figure Description

[0051] Figure 1 This is a scanning electron microscope image of the surface of the composite solid electrolyte in Embodiment 1 of the present invention.

[0052] Figure 2 The image shows the electrochemical impedance spectroscopy of the composite solid electrolyte of Example 1 of this invention at 25°C and relative humidity RH < 50%.

[0053] Figure 3 This is a graph showing the ionic conductivity of the composite solid electrolyte of Example 1 of the present invention at different temperatures.

[0054] Figure 4 This is a linear sweep voltammetry diagram of the composite solid electrolyte of Example 1 of the present invention.

[0055] Figure 5 The images show the chronoamperometry plot, electrochemical impedance spectroscopy plot before and after the chronoamperometry plot of the composite solid electrolyte in Example 1 of this invention.

[0056] Figure 6 The graph shows the constant current cycling of the lithium symmetric battery assembled with the composite solid electrolyte of Example 1 of the present invention at different current densities at 26°C.

[0057] Figure 7 The lithium symmetric battery assembled with the composite solid electrolyte of Example 1 of this invention operates at -20°C and 0.1 mA / cm². -2 Graph of constant current cycling performance at current density.

[0058] Figure 8 The graph shows the cycling performance of the full cell assembled with the composite solid electrolyte of Example 1 of the present invention at 30°C and 0.2C rate.

[0059] Figure 9 This is a scanning electron microscope image of the surface of the composite solid electrolyte in Embodiment 2 of the present invention.

[0060] Figure 10 The electrochemical impedance spectroscopy (EIS) spectra of the composite solid electrolyte of Example 2 of this invention at 25°C and -30°C are shown.

[0061] Figure 11 This is a linear sweep voltammetry diagram of the composite solid electrolyte of Example 2 of the present invention.

[0062] Figure 12 The images show the chronoamperometry plot, electrochemical impedance spectroscopy plot before and after the chronoamperometry plot of the composite solid electrolyte in Example 2 of this invention.

[0063] Figure 13 The lithium symmetric battery assembled with the composite solid electrolyte of Example 2 of the present invention was tested at 26°C and 0.1 mA / cm². -2 Graph of constant current cycling performance at current density.

[0064] Figure 14 The graph shows the cycling performance of the full cell assembled with the composite solid electrolyte in Example 2 of this invention at 30°C and 0.2C rate.

[0065] Figure 15 This is a scanning electron microscope image of the surface of a two-dimensional material randomly arranged composite solid electrolyte of Comparative Example 1 of the present invention.

[0066] Figure 16 The electrochemical impedance spectroscopy (EIS) spectrum of the two-dimensional material randomly arranged composite solid electrolyte of Comparative Example 1 of this invention is shown in the figure at 25°C and relative humidity RH < 50%.

[0067] Figure 17 This is a linear sweep voltammetry diagram of a two-dimensional material randomly arranged composite solid electrolyte of Comparative Example 1 of the present invention.

[0068] Figure 18 The images show the chronoamperometry plots of the two-dimensional material randomly arranged composite solid electrolyte of Comparative Example 1 of this invention, as well as the electrochemical AC impedance spectra before and after the chronoamperometry plots. Detailed Implementation

[0069] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the present invention will now be described in detail below, but this should not be construed as limiting the scope of the invention.

[0070] Example 1

[0071] Li 0.3 Cd 0.85 Preparation of PS3 nanosheet dispersion:

[0072] (a) Preparation of CdPS3 single crystals by chemical vapor transport method: Cadmium, phosphorus, sulfur and iodine were mixed in a mass ratio of 1.686:0.464:1.44:0.2, placed in a quartz tube and sealed under vacuum to -0.1 MPa. The material end of the sealed quartz tube was heated to 700°C and the other end was heated to 630°C. After reacting for 168 hours, the mixture was cooled to room temperature. The product was washed with ethanol to obtain CdPS3 single crystals.

[0073] (b) A first ion-exchange intercalation reaction was carried out in a mixed solution containing potassium salt and ethylenediaminetetraacetic acid (EDTA). The potassium salt was potassium chloride and potassium carbonate. The concentration of the potassium salt in the mixed solution was 2 mol / L (potassium chloride and potassium carbonate were each 1 mol / L), the concentration of EDTA was 2 mol / L, and the content of CdPS3 single crystal in the mixed solution was 0.01 g / mL. The temperature of the first ion-exchange intercalation hydrothermal reaction was 100 °C, and the time was 2 h. After the reaction, the product was washed to obtain K. x Cd y PS3 blocks;

[0074] (c) K x Cd y The PS3 block was placed in an aqueous solution containing lithium salt for a second ion exchange intercalation reaction. The lithium salt was LiCl, and the concentration of the lithium salt in the aqueous solution was 2 mol / L. x Cd y The PS3 bulk content in the lithium salt-containing aqueous solution was 0.01 g / mL. The second ion exchange intercalation hydrothermal reaction was carried out at 100°C for 2 hours. After the reaction, the product was washed to obtain Li. 0.3 Cd 0.85 PS3 blocks;

[0075] (d) Li 0.3 Cd 0.85 The PS3 block was placed in deionized water and subjected to ultrasonic treatment for peeling, followed by centrifugation. The ultrasonic treatment power was 100W for 30 minutes, and the centrifugation rate was 2000 rpm for 5 minutes, yielding a Li-containing product. 0.3 Cd 0.85 Dispersion of PS3 nanosheets.

[0076] Li in the dispersion 0.3 Cd 0.85 The concentration of PS3 nanosheets was 0.006 g / mL. The nanosheets in this dispersion were predominantly monolayer nanosheets. Transmission electron microscopy was used to measure the lateral dimensions of the nanosheets, and atomic force microscopy was used to measure their thickness. The dimensions of all materials in the test field were averaged, yielding an average thickness of 1 nm and an average lateral dimension of 0.2 μm for the nanosheets in this dispersion.

[0077] Preparation of two-dimensional material thin films:

[0078] Li-containing 0.3 Cd 0.85The dispersion of PS3 nanosheets was vacuum filtered. The core of the vacuum filtration device had a diameter of 10 cm. The vacuum filtration used an aqueous microporous membrane with a pore size of 0.45 μm and a diameter of 11 cm. The filtration was carried out under a vacuum of 0.1 MPa for 30 min until the formed film had no obvious moisture. Then, it was vacuum dried at 60 °C for 20 h to obtain a two-dimensional material film.

[0079] The two-dimensional material film has a thickness of approximately 20 μm and an area of ​​60 cm². 2 The mass is approximately 0.25 g. In this two-dimensional material film, the number of nanosheets arranged along the plane of the film and its parallel direction accounts for more than 60% of the total number of nanosheets, that is, the degree of orientation is more than 60%. The degree of orientation of the nanosheets in the film is tested by 2D-XRD, and the degree of orientation is calculated by the orientation factor. Several two-dimensional material films were prepared in the same way and cut into 2×2 cm pieces.

[0080] Preparation of polymer-containing slurries:

[0081] Combine 1g PEO, 0.4g LiTFSI, 0.05g Li 0.3 Cd 0.85 PS3 nanosheets (using Li-containing nanosheets) 0.3 Cd 0.85 A dispersion of PS3 nanosheets (obtained by drying) was dispersed in 16 mL of acetonitrile to obtain a polymer-containing slurry. Several batches of polymer-containing slurries were prepared in the same manner.

[0082] Preparation of composite solid electrolytes:

[0083] A polytetrafluoroethylene (PTFE) sheet (substrate, 2×2cm) was placed on a spin coater. A first portion of polymer-containing slurry was spin-coated onto the PTFE sheet surface at a spin speed of 500 rpm for 30 seconds at 25°C. The slurry was then heated on a 60°C heating plate for 60 seconds to remove some of the solvent, resulting in a first polymer-containing film. One side of the first two-dimensional material film was then adhered to the first polymer-containing film, and a pressure of 10 MPa was applied. A second portion of polymer-containing slurry was spin-coated onto the other side of the two-dimensional material film at a spin speed of 500 rpm for 30 seconds at 25°C. The slurry was then heated on a 60°C heating plate for 60 seconds to remove some of the solvent, resulting in a second polymer-containing film. Finally, one side of the second two-dimensional material film was adhered to the second polymer-containing film... A pressure of 10 MPa is applied to the film; the polymer-containing slurry is spin-coated and the two-dimensional material film is bonded alternately to obtain a block with alternating polymer-containing film and two-dimensional material film, the volume of which is 2×2×2 cm; the block includes alternating polymer film and two-dimensional material film, each polymer-containing film having a thickness of about 30 μm; the block is placed in a vacuum drying oven and vacuum dried at 60°C for 24 h, then cold-pressed at 10 MPa using a tablet press, the pressure is maintained for 60 s, and then stored in a glove box for 48 h; the block is removed from the glove box and placed in a cryostat for slicing, the cryostat is set at -20°C, and the slicing angle is 90° with the plane direction of the polymer-containing film and the two-dimensional material film, to obtain a two-dimensional material-based composite solid electrolyte with a vertically aligned structure.

[0084] The thickness of the two-dimensional material-based composite solid electrolyte with a vertically aligned structure is approximately 100 μm. Based on the total mass of the two-dimensional material-based composite solid electrolyte with a vertically aligned structure (100%), the content of the two-dimensional material film is 20%, and the content of the polymer-containing film is 80%. The area of ​​the composite solid electrolyte is 2 × 2 cm.

[0085] Depend on Figure 1 As can be seen, the two-dimensional material-based composite solid electrolyte with a vertically arranged structure prepared in this embodiment consists of alternating layers of two-dimensional material and polymer material, and the two-dimensional material exhibits a vertically arranged structure within the surface of the composite solid electrolyte.

[0086] Depend on Figure 2 As can be seen, the two-dimensional material-based composite solid electrolyte with a vertically aligned structure prepared in this embodiment has an ionic conductivity of 4.54 mS / cm measured at room temperature (25°C) and relative humidity RH < 50%. -1 It has high ionic conductivity at room temperature.

[0087] Depend on Figure 3 It can be seen that the two-dimensional material-based composite solid electrolyte with a vertically arranged structure prepared in this embodiment has high ionic conductivity at different temperatures.

[0088] Depend on Figure 4 It can be seen that the two-dimensional material-based composite solid electrolyte with vertically arranged structure prepared in this embodiment has an electrochemical stability window of 5V, which is a wide electrochemical stability window.

[0089] Depend on Figure 5 It can be seen that the lithium-ion transfer number of the two-dimensional material-based composite solid electrolyte with a vertically arranged structure prepared in this embodiment is 0.67.

[0090] Depend on Figure 6 As can be seen, the lithium symmetric battery assembled with a two-dimensional material-based composite solid electrolyte with a vertically aligned structure prepared in this embodiment achieves a performance of 0.1 mA / cm². -2 The overpotential is 12mV under current density and 26℃ test conditions, and at 0.5mAcm -2 The overpotential was 18 mV under the current density and 26 °C test conditions, indicating that the prepared electrolyte has excellent lithium deposition stripping ability. The structure of this lithium symmetric battery is Li|electrolyte|Li, and the thickness of the lithium foil is 60 μm.

[0091] Depend on Figure 7 As can be seen, the lithium symmetric battery assembled with a two-dimensional material-based composite solid electrolyte with a vertically aligned structure prepared in this embodiment achieves a performance of 0.1 mA / cm². -2 The overpotential of 16mV under current density and -20℃ testing conditions indicates that the prepared electrolyte still has excellent lithium deposition stripping ability at low temperatures, implying excellent performance over a wide temperature range. The structure of this lithium symmetric battery is as described above.

[0092] Depend on Figure 8 As can be seen, the full cell assembled from the two-dimensional material-based composite solid electrolyte with a vertically aligned structure prepared in this embodiment retains 98% of its capacity after 40 cycles at 30°C and 0.2C rate, demonstrating high full cell cycle performance. The structure of this full cell is LiFePO4|electrolyte|Li, and the positive electrode LiFePO4 loading is 1 mg / cm³. 2 The thickness of the negative electrode lithium foil is 60μm.

[0093] Example 2

[0094] Li 0.46 Mn 0.77 Preparation of PS3 nanosheet dispersion:

[0095] (a) Preparation of MnPS3 single crystals by chemical vapor transport method: Manganese, phosphorus, sulfur and iodine were mixed in a mass ratio of 0.8241:0.464:1.44:0.2, placed in a quartz tube and sealed by evacuation to -0.1 MPa. The material end of the sealed quartz tube was heated to 700°C and the other end was heated to 630°C. After reacting for 168 hours, the mixture was cooled to room temperature. The product was washed with ethanol to obtain MnPS3 single crystals.

[0096] (b) MnPS3 single crystals were placed in a mixed solution containing potassium salts, namely potassium chloride and potassium carbonate, for a first ion exchange intercalation reaction. The concentration of potassium salts in the mixed solution was 2 mol / L (potassium chloride and potassium carbonate were each 1 mol / L). The content of MnPS3 single crystals in the mixed solution was 0.01 g / mL. The temperature of the first ion exchange intercalation hydrothermal reaction was 100 °C and the time was 2 h. After the reaction was completed, the product was washed to obtain K. x Mn y PS3 blocks;

[0097] (c) K x Mn y The PS3 block was placed in an aqueous solution containing lithium salt for a second ion exchange intercalation reaction. The lithium salt was LiCl, and the concentration of the lithium salt in the aqueous solution was 2 mol / L. x Mn y The PS3 bulk content in the lithium salt-containing aqueous solution was 0.01 g / mL. The second ion exchange intercalation hydrothermal reaction was carried out at 100°C for 2 hours. After the reaction, the product was washed to obtain Li. 0.46 Mn 0.77 PS3 blocks;

[0098] (d) Li 0.46 Mn 0.77 The PS3 block was placed in deionized water and subjected to ultrasonic treatment for peeling, followed by centrifugation. The ultrasonic treatment power was 100W for 30 minutes, and the centrifugation rate was 2000 rpm for 5 minutes, yielding a Li-containing product. 0.46 Mn 0.77 Dispersion of PS3 nanosheets.

[0099] Li in the dispersion 0.46 Mn 0.77The concentration of PS3 nanosheets was 0.006 g / mL. The nanosheets in this dispersion were predominantly monolayer nanosheets. Transmission electron microscopy was used to measure the lateral dimensions of the nanosheets, and atomic force microscopy was used to measure their thickness. The dimensions of all materials in the test field were averaged, yielding an average thickness of 1.2 nm and an average lateral dimension of 0.3 μm for the nanosheets in this dispersion.

[0100] Preparation of two-dimensional material thin films:

[0101] Li-containing 0.46 Mn 0.77 The dispersion of PS3 nanosheets was vacuum filtered. The core of the vacuum filtration device had a diameter of 10 cm. The vacuum filtration used an aqueous microporous membrane with a pore size of 0.45 μm and a diameter of 11 cm. The filtration was carried out under a vacuum of 0.1 MPa for 30 min until the formed film had no obvious moisture. Then, it was vacuum dried at 60 °C for 20 h to obtain a two-dimensional material film.

[0102] The two-dimensional material film has a thickness of approximately 30 μm and an area of ​​60 cm². 2 The mass is approximately 0.25 g. In this two-dimensional material film, the number of nanosheets arranged along the plane of the film and its parallel direction accounts for more than 60% of the total number of nanosheets. Several two-dimensional material films were prepared in the same manner and cut into 2×2 cm pieces.

[0103] Preparation of polymer-containing slurries:

[0104] Combine 1g PEO, 0.4g LiTFSI, 0.05g Li 0.46 Mn 0.77 PS3 nanosheets (using Li-containing nanosheets) 0.46 Mn 0.77 A dispersion of PS3 nanosheets (obtained by drying) was dispersed in 16 mL of acetonitrile to obtain a polymer-containing slurry. Several batches of polymer-containing slurries were prepared in the same manner.

[0105] Preparation of composite solid electrolytes:

[0106] A polytetrafluoroethylene (PTFE) sheet (substrate, 2×2cm) was placed on a spin coater. A first portion of polymer-containing slurry was spin-coated onto the PTFE sheet surface at a spin speed of 500 rpm for 30 seconds at 25°C. The slurry was then heated on a 60°C heating plate for 60 seconds to remove some of the solvent, resulting in a first polymer-containing film. One side of the first two-dimensional material film was then adhered to the first polymer-containing film, and a pressure of 10 MPa was applied. A second portion of polymer-containing slurry was spin-coated onto the other side of the two-dimensional material film at a spin speed of 500 rpm for 30 seconds at 25°C. The slurry was then heated on a 60°C heating plate for 60 seconds to remove some of the solvent, resulting in a second polymer-containing film. Finally, one side of the second two-dimensional material film was adhered to the second polymer-containing film... A pressure of 10 MPa was applied to the film; the polymer-containing slurry was spin-coated and the two-dimensional material film was bonded alternately to obtain a block with alternating polymer-containing film and two-dimensional material film, the volume of which was 2×2×2 cm; the block consisted of alternating polymer film and two-dimensional material film, each polymer-containing film having a thickness of approximately 30 μm; the block was placed in a vacuum drying oven and vacuum dried at 60°C for 24 h, then cold-pressed at 10 MPa using a tablet press, the pressure was maintained for 60 s, and then stored in a glove box for 48 h; the block was removed from the glove box and placed in a cryostat for slicing, the cryostat was set at -20°C, and the slicing angle was 90° to the plane direction of the polymer-containing film and the two-dimensional material film, to obtain a two-dimensional material-based composite solid electrolyte with a vertically aligned structure.

[0107] The thickness of the two-dimensional material-based composite solid electrolyte with a vertically aligned structure is approximately 100 μm. Based on the total mass of the two-dimensional material-based composite solid electrolyte with a vertically aligned structure (100%), the content of the two-dimensional material film is 20%, and the content of the polymer-containing film is 80%. The area of ​​the composite solid electrolyte is 2 × 2 cm.

[0108] Depend on Figure 9 As can be seen, the two-dimensional material-based composite solid electrolyte with a vertically arranged structure prepared in this embodiment consists of alternating layers of two-dimensional material and polymer material, and the two-dimensional material exhibits a vertically arranged structure within the surface of the composite solid electrolyte.

[0109] Depend on Figure 10 As can be seen, the two-dimensional material-based composite solid electrolyte with a vertically aligned structure prepared in this embodiment has an ionic conductivity of 0.6 mS / cm measured at room temperature (25°C) and relative humidity RH < 50%. -1 The ionic conductivity measured under conditions of -30℃ and relative humidity (RH) < 50% was 0.04 mS / cm.-1 It has high ionic conductivity.

[0110] Depend on Figure 11 As can be seen, the two-dimensional material-based composite solid electrolyte with a vertically aligned structure prepared in this embodiment has an electrochemical stability window of 5.3V, exhibiting a wide electrochemical stability window.

[0111] Depend on Figure 12 It can be seen that the lithium-ion transfer number of the two-dimensional material-based composite solid electrolyte with a vertically arranged structure prepared in this embodiment is 0.42.

[0112] Depend on Figure 13 As can be seen, the lithium symmetric battery assembled with a two-dimensional material-based composite solid electrolyte with a vertically aligned structure prepared in this embodiment achieves a performance of 0.1 mA / cm². -2 It exhibits excellent lithium deposition stripping capability under current density and 26°C testing conditions. The structure of this lithium symmetric cell is the same as that of Example 1.

[0113] Depend on Figure 14 As can be seen, the full cell assembled from the two-dimensional material-based composite solid electrolyte with a vertically aligned structure prepared in this embodiment retains 96% of its capacity after 60 cycles at 30°C and 0.2C rate, demonstrating high full cell cycle performance. The structure of this full cell is the same as that in Example 1.

[0114] Comparative Example 1

[0115] Comparative Example 1 is compared with Example 1: the two-dimensional material film prepared in Example 1 (with a thickness of approximately 20 μm and an area of ​​60 cm²) was used. 2 A mixture of approximately 0.25 g of polymer-containing material was added to the polymer-containing slurry prepared in Example 1 and stirred to obtain a mixed slurry. Several portions of this mixed slurry were then cast onto polytetrafluoroethylene (PTFE) plates in batches. After each casting, the solvent was removed by heating until a block with a volume of 2×2×2 cm was formed. The block was placed in a vacuum drying oven and dried under vacuum at 60°C for 24 hours. Then, it was cold-pressed using a tablet press at a pressure of 10 MPa for 60 seconds, and then stored in a glove box for 48 hours. After that, it was removed from the glove box and placed in a cryostat for sectioning. The cryostat was set to a temperature of -20°C to prepare a composite solid electrolyte with a thickness of 100 μm and random arrangement of two-dimensional materials. The total mass of the composite solid electrolyte was 100%, of which the content of two-dimensional materials was 20% and the content of the polymer-containing film was 80%. During the testing process, it was found that the performance of the composite solid electrolyte with random arrangement of two-dimensional materials prepared in this comparative example was much worse than that of Example 1.

[0116] Depend on Figure 15It can be seen that the two-dimensional material randomly arranged composite solid electrolyte prepared in this comparative example cannot observe the structure of alternating layers of two-dimensional material and polymer, with the two-dimensional material randomly distributed inside the polymer.

[0117] Depend on Figure 16 As can be seen, the ionic conductivity of the two-dimensional material randomly arranged composite solid electrolyte prepared in this comparative example is 0.012 mS / cm, measured under the conditions of room temperature (25℃) and relative humidity RH < 50%. -1 It has a lower ionic conductivity compared to Example 1.

[0118] Depend on Figure 17 It can be seen that the electrochemical stability window of the randomly arranged two-dimensional composite solid electrolyte prepared in this comparative example is <4.5V, and its electrochemical stability is worse than that of Example 1.

[0119] Depend on Figure 18 It can be seen that the lithium-ion transfer number of the randomly arranged two-dimensional material composite solid electrolyte prepared in this comparative example is 0.35, which is less than that of Example 1, where the lithium-ion transfer number is 0.67.

Claims

1. A method for preparing a two-dimensional material-based composite solid-state electrolyte with a vertical arrangement structure, comprising the following steps: (1) preparing a two-dimensional material film using a dispersion liquid of two-dimensional nanosheets; (2) dispersing a polymer, a lithium salt and two-dimensional nanosheets in an organic solvent to obtain a polymer-containing slurry; (3) spin-coating the polymer-containing slurry on a substrate, and then heating to obtain a first polymer-containing film; pasting one side of the two-dimensional material film to the first polymer-containing film and applying pressure to obtain a composite structure of a polymer-containing film and a two-dimensional material film; (4) spin-coating the polymer-containing slurry on the surface of the two-dimensional material film of the composite structure, and then heating to obtain a second polymer-containing film; then pasting one side of the two-dimensional material film to the second polymer-containing film and applying pressure; alternately repeating the spin-coating of the polymer-containing slurry and the pasting of the two-dimensional material film for several times to obtain a bulk with several layers of polymer-containing films and two-dimensional material films arranged alternately; (5) drying, cold-pressing and slicing the bulk to obtain the two-dimensional material-based composite solid-state electrolyte with a vertical arrangement structure. The two-dimensional nanosheets comprise one or more of the compounds represented by the following formula (i): wherein M comprises one or more of Cd, Mn, Fe, Co, Ni, Zn and Cr, y is a number of 0.5-1, and x = 2 × (1-y); and the average thickness of the two-dimensional nanosheets is 0.6-10 nm, and the average lateral size is 0.1-10 μm. The step (1) specifically comprises: vacuum suction filtering the dispersion liquid of two-dimensional nanosheets, wherein the sand core diameter of the vacuum suction filtering device is 1-10 cm, the water-based microporous filter membrane used in the vacuum suction filtering has a pore size of 0.1-1 μm and a diameter of 2-1000 cm, the vacuum suction filtering is performed at a vacuum degree of 0.001-0.1 MPa for 1-1000 min, and then vacuum drying is performed at 60-100℃ for 1-20 h to obtain the two-dimensional material film. Preferably, the concentration of the two-dimensional nanosheets in the dispersion liquid of the two-dimensional nanosheets is 0.001-0.02 g / mL. The thickness of the two-dimensional material film is 10-50 μm. Preferably, in the two-dimensional material film, the number of nanosheets arranged in the plane direction and parallel direction of the film accounts for more than 60% of the total number of nanosheets.

2. The production method according to claim 1, wherein, The two-dimensional nanosheets are two-dimensional materials having an ionic conductivity > 1 x 10 -6 S cm -1 at room temperature, in conditions of relative humidity RH < 50%.

3. The production method according to claim 2, wherein, The polymer comprises one or more of polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, polypropylene oxide and polyvinylidene chloride. Li x M y PS3 Formula (i) The lithium salt comprises one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium oxide, lithium fluoride, lithium bis(fluorosulfonyl)imide, lithium nitride, lithium nitrate and lithium hexafluorophosphate. Preferably, the two-dimensional nanosheets comprise Li 0.46 Mn 0.77 PS3 and Li 0.3 Cd 0.85 one or both of PS3.

4. The production method according to claim 1, wherein The mass ratio of the polymer, the lithium salt and the two-dimensional nanosheets is 1: 0.1-0.4: 0.01-0.

15.

5. The production method according to claim 1, wherein Preferably, the content of the polymer in the organic solvent is 0.05-0.08 g / mL. ​ 6. The production method according to claim 1, wherein ​ ​ 7. The production method according to claim 1, wherein ​ 8. The production method according to claim 1, wherein ​ 9. The production method according to claim 1, wherein, ​ ​ 10. The production method according to claim 1, wherein, The rotation speed of the polymer-containing slurry is 10-3000 r / min, the time is 10-600 s, and the temperature is -30-200℃. Preferably, the rotation speed of the polymer-containing slurry is 100-1000 r / min, the time is 30-120 s, and the temperature is 25-60℃.

11. The method of producing according to claim 1, wherein, The thickness of the polymer-containing film is 10-50 μm.

12. The method of producing according to claim 1, wherein, One side of the two-dimensional material film is attached to the polymer-containing film, and the applied pressure is 0.1-200 MPa. Preferably, the applied pressure is 20-50 MPa.

13. The method of producing according to claim 1, wherein, The section is obtained by using a freezing microtome, the setting temperature of the freezing microtome is -30--1℃, and the angle of the section is 30-90° with the plane direction of the polymer-containing film and the two-dimensional material film.

14. A two-dimensional material-based composite solid-state electrolyte with a vertical arrangement structure, which is prepared by the method for preparing a two-dimensional material-based composite solid-state electrolyte with a vertical arrangement structure according to any one of claims 1-13. Preferably, the thickness of the two-dimensional material-based composite solid-state electrolyte with a vertical arrangement structure is 10-1000 μm. Preferably, the content of the two-dimensional material film is 5-95%, and the content of the polymer-containing film is 5-95% in the two-dimensional material-based composite solid-state electrolyte with a vertical arrangement structure, based on 100% of the total mass of the two-dimensional material-based composite solid-state electrolyte with a vertical arrangement structure.

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