Silicon-based solid-state electrolyte and preparation method therefor, electrode sheet, and all-solid-state battery

Abstract

A silicon-based solid-state electrolyte and a preparation method therefor, an electrode sheet, and an all-solid-state battery. The silicon-based solid-state electrolyte has the composition represented by formula I: LiaSibXxYy(I), wherein X is selected from at least one of negative monovalent groups; Y is selected from at least one of negative divalent groups and / or negative trivalent groups; and 1≤a≤6, 0.5≤b≤2, 0≤x≤6, 0≤y≤6, and x and y are not 0 at the same time The provided silicon-based solid-state electrolyte not only has a high ionic conductivity and good deformability, but also has a low Push's ratio and low costs; and the silicon-based solid-state electrolyte is used in an all-solid-state battery, thereby improving the electrochemical performance of the battery.

Description

Silicon-based solid electrolytes and their preparation methods, electrodes, and all-solid-state batteries

[0001] Cross-references to related applications

[0002] This application claims the benefit of Chinese Patent Application No. 202411998702.3, filed on December 31, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of battery technology, specifically to a silicon-based solid electrolyte, a method for preparing a silicon-based solid electrolyte, an electrode containing a silicon-based solid electrolyte, and an all-solid-state battery. Background Technology

[0004] All-solid-state batteries have a similar structure to currently commercialized lithium batteries. Their energy density is determined by the active material. However, the cathode materials are currently all oxides, which are extremely rigid and have insufficient contact between particles. In common commercial lithium batteries, electrolytes are used to achieve lithium-ion transport between cathode material particles. In all-solid-state batteries, lithium-ion transport between rigid materials mainly relies on solid electrolytes doped between cathode materials to form composite electrodes, which meet the requirements of ion transport. Solid electrolytes are the key core material of all-solid-state lithium batteries.

[0005] Currently available inorganic solid electrolytes, such as oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes, each have their own shortcomings in the mass production of all-solid-state batteries. Oxide solid electrolytes are too rigid and cannot fully contact the active material particles. Sulfide solid electrolytes and halide solid electrolytes mostly contain various metal cations, which leads to higher material costs and higher requirements for the manufacturing environment, further increasing the overall cost of all-solid-state lithium batteries.

[0006] Therefore, simultaneously meeting the requirements of all-solid-state batteries for electrolyte ionic conductivity and low-cost solid electrolytes is currently the main development direction. Summary of the Invention

[0007] The purpose of this invention is to overcome the above-mentioned technical problems and provide a silicon-based solid electrolyte, a method for preparing a silicon-based solid electrolyte, an electrode containing a silicon-based solid electrolyte, and an all-solid-state battery.

[0008] To achieve the above objectives, a first aspect of the present invention provides a silicon-based solid electrolyte having the composition shown in Formula I, Li a Si b X x Y y(I); wherein X is selected from at least one of the negative monovalent groups, and Y is selected from at least one of the negative divalent and / or negative trivalent groups; 1≤a≤6, 0.5≤b≤2, 0≤x≤6, 0≤y≤6, and x and y are not simultaneously 0.

[0009] Preferably, in formula I, X is selected from F - Cl - ,Br - I - CN - OCN - SCN - and N3 - At least one of them.

[0010] Preferably, in formula I, Y is selected from O 2- S 2- Se 2- Te 2- N 3- P 3- As 3- Sb 3- and Bi 3- At least one of them.

[0011] A second aspect of the present invention provides a method for preparing a silicon-based solid electrolyte, the method comprising: mixing raw materials and ball milling them in an inert atmosphere to obtain a silicon-based solid electrolyte having the composition shown in Formula I;

[0012] Among them, Li a Si b X x Y y (I); wherein X is selected from at least one of the negative monovalent groups, and Y is selected from at least one of the negative divalent and / or negative trivalent groups; 1≤a≤6, 0.5≤b≤2, 0≤x≤6, 0≤y≤6, and x and y are not simultaneously 0.

[0013] A third aspect of the present invention provides an electrode, the electrode comprising: a silicon-based solid electrolyte provided in the first aspect, or a silicon-based solid electrolyte prepared by the preparation method provided in the second aspect; wherein the electrode is a positive electrode or a negative electrode.

[0014] A fourth aspect of the present invention provides an all-solid-state battery, the all-solid-state battery comprising a positive electrode, a negative electrode and an electrolyte;

[0015] The positive electrode, negative electrode, and electrolyte each independently contain a silicon-based solid electrolyte provided in the first aspect, or a silicon-based solid electrolyte prepared by the preparation method provided in the second aspect.

[0016] Through the above technical solution, the silicon-based solid electrolyte provided by the present invention, by doping with non-metallic Si and mixing with anions X and / or Y, effectively controls the ionic conductivity, Push's ratio and shear modulus of the silicon-based solid electrolyte, and has high ionic conductivity and excellent deformation ability, thereby promoting full contact between it and active material particles, improving the solid-solid interface contact problem of all-solid batteries, and improving the electrochemical performance of the battery, especially the rate performance and cycle performance.

[0017] Meanwhile, the silicon-based solid electrolyte provided by this invention not only has excellent room temperature ionic conductivity, but also high temperature ionic conductivity, thereby improving the chemical performance of the battery under different operating conditions. Attached Figure Description

[0018] Figure 1a is an XPS diagram of the silicon-based solid electrolyte S1 prepared in Example 1;

[0019] Figure 1b is an XPS image of the raw material SiI4 provided in Example 1;

[0020] Figure 2 is the EIS diagram of the silicon-based solid electrolyte S1 prepared in Example 1 at 25°C and 60°C.

[0021] Figure 3a is the XRD pattern of the silicon-based solid electrolyte S1 prepared in Example 1;

[0022] Figure 3b is the XRD pattern of the raw material SiI4 provided in Example 1;

[0023] Figure 3c is the XRD pattern of the raw material Li2O provided in Example 1. Detailed Implementation

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0025] The first aspect of this invention provides a silicon-based solid electrolyte having the composition shown in Formula I, Li a Si b X x Y y (I); wherein X is selected from at least one of the negative monovalent groups, and Y is selected from at least one of the negative divalent and / or negative trivalent groups; 1≤a≤6, 0.5≤b≤2, 0≤x≤6, 0≤y≤6, and x and y are not simultaneously 0.

[0026] In this invention, unless otherwise specified, x and y not being 0 at the same time means x = 0 and y ≠ 0, or x ≠ 0 and y = 0, or x ≠ 0 and y ≠ 0.

[0027] In some embodiments of the present invention, when x = 0 and y ≠ 0, or x ≠ 0 and y = 0, the silicon-based solid electrolyte is a ternary substance composed of Li, Si, and X / Y, wherein Li and Si are cations and X / Y are anions; when x ≠ 0 and y ≠ 0, the silicon-based solid electrolyte is a quaternary substance composed of Li, Si, X, and Y, wherein Li and Si are cations and X and Y are anions.

[0028] In this invention, in Formula I, non-metallic Si is used for doping. Compared with metal cation doping, this not only significantly reduces costs but also has a low electrochemical reduction window and is stable to the negative electrode. At the same time, this invention uses anions X and / or Y, which can effectively control the sublattice packing form, improve ionic conductivity, and effectively control the deformability of silicon-based solid electrolytes, such as Push's ratio and shear modulus, thereby promoting sufficient contact between them and active particles and improving ionic conductivity.

[0029] In some embodiments of the present invention, preferably, in formula I, X is selected from F - Cl - ,Br - I - CN - OCN - SCN - and N3 - At least one of them.

[0030] In some embodiments of the present invention, more preferably, in formula I, X is selected from F - Cl - ,Br - and I - At least one of them.

[0031] In some embodiments of the present invention, more preferably, in Formula I, X is selected from Cl - ,Br - and I - At least one of them.

[0032] In this invention, X-types that meet the above-mentioned range have relatively high polarizability, making them easy to act as carriers to combine with and transport lithium ions. Anions with higher electronegativity can improve the oxidative stability of the electrolyte, while anions with lower electronegativity can improve the reducing stability of the electrolyte. Some larger anions can form a more loose anion stacking form, expanding the lithium ion transport channel, and have a greater probability of combining with lithium ions, accelerating lithium ion transport and improving ionic conductivity.

[0033] In some embodiments of the present invention, preferably, in Formula I, Y is selected from O 2- S 2- Se 2- Te 2- N 3- P 3- As 3- Sb 3- and Bi 3- At least one of them.

[0034] In some embodiments of the present invention, more preferably, in formula I, Y is selected from O 2- S 2- N 3- and P 3- At least one of them.

[0035] In some embodiments of the present invention, more preferably, in Formula I, Y is selected from O 2- and / or P 3- .

[0036] In this invention, Y types that satisfy the above-mentioned range repel X anions, causing the Si-X bond to lengthen, in Si-X-Li + During its self-rotation process, it is easier to transport lithium ions to other Si-X groups, thereby improving ionic conductivity.

[0037] In some preferred embodiments of the present invention, in Formula I, X is selected from Cl - ,Br - and I - At least one of them; Y is selected from O 2- and / or P 3- .

[0038] In some embodiments of the present invention, preferably, in Formula I, a / b = 0.5-6, for example, 0.5, 1, 1.5, 2, 2.5, 3, 3.3, 4, 5, 6, and any value within the range of any two values, preferably 1.5-3. In the present invention, by adjusting the molar ratio of Li and Si, the proportion of the amorphous phase in the electrolyte is adjusted, thereby affecting the overall lithium-ion transport performance.

[0039] In some embodiments of the present invention, preferably, in Formula I, x / (x+y) = 0.5-1, for example, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95, 0.98, 1, and any value within the range of any two values, preferably 0.8-1. In the present invention, by controlling the molar ratio of X in the anion, the Si-X bond length is controlled, thereby reducing the ease of lithium ion transport between Si-X groups and improving lithium ion conductivity.

[0040] In some embodiments of the present invention, preferably, in formula I, b / (x+y) = 1:7-1:1, for example, 1:7, 1:6.5, 1:6, 1:5.8, 1:5.5, 1:5.2, 1:5, 1:4.8, 1:4.5, 1:4.2, 1:4, 1:3, 1:2, 1:1, and any value within the range of any two values, preferably 1:6-1:4.

[0041] In this invention, unless otherwise specified, a, b, x, and y can be integers or any numbers that satisfy the above range.

[0042] In some embodiments of the present invention, in formula I, 1≤a≤6, for example, 1, 2, 3, 4, 5, 6, and any value in the range of any two numerical values, preferably 1≤a≤3.

[0043] In some embodiments of the present invention, in Formula I, 0.5≤b≤2, for example, 0.5, 0.6, 0.8, 1, 1.2, 1.5, 1.8, 2, and any value in the range of any two values, preferably 1≤b≤2.

[0044] In some embodiments of the present invention, in formula I, 0≤x≤6, for example, 0, 1, 2, 2.4, 3, 3.2, 4, 5, 6, and any value in the range of any two values, preferably 1≤x≤6.

[0045] In some embodiments of the present invention, in formula I, 0≤y≤6, for example, 0, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, and any value in the range of any two values, preferably 0.5≤y≤2.

[0046] In some specific embodiments of the present invention, preferably, the silicon-based solid electrolyte is selected from Li2SiI4O, Li2SiI6, Li2SiCl6, and Li2SiI4ClO. 0.5 Li2SiI4BrO 0.5, Li2SiCl4O, Li2SiBr6, Li2SiBr4O, Li2SiI2Br2O, Li2SiI2Cl2O, Li2SiI2O2, Li2SiBr2O2, Li2SiCl2O2, Li2Si 0.8 I 3.2 O, Li2Si 0.6 I 2.4 O, Li2Si 0.8 Cl 3.2 O, Li2Si 0.8 Br 3.2 O, Li2Si 0.6 Cl 2.4 O, Li2Si 0.6 Br 2.4 At least one of O, Li2SiI4S, Li2SiBr4S, Li2SiCl4S, Li2SiS, Li2SiCl3N, Li2SiCl3P, and Li2SiI3P.

[0047] In this invention, more preferably, the silicon-based solid electrolyte is selected from the LiSiIO series, LiSiBrO series, and LiSiClO series. For example, the silicon-based solid electrolyte is selected from Li2SiI4O, Li2SiBr4O, Li2SiCl4O, Li2SiI2O2, Li2SiBr2O2, Li2SiCl2O2, and Li2Si... 0.8 I 3.2 O, Li2Si 0.8 Br 3.2 O, Li2Si 0.8 Cl 3.2 O, Li2Si 0.6 I 2.4 O, Li2Si 0.6 Br 2.4 O and Li2Si 0.6 Cl 2.4 At least one of O.

[0048] In this invention, the preparation method of the silicon-based solid electrolyte has a wide range of options, as long as the above limitations are met. Preferably, the silicon-based solid electrolyte is prepared by ball milling raw materials based on the molar ratio of elements in Formula I in an inert atmosphere.

[0049] In some embodiments of the present invention, preferably, the silicon-based solid electrolyte satisfies the following condition: the ratio of ionic conductivity at 60°C to ionic conductivity at 25°C is ≤6, for example, 6, 5.5, 5, 4.5, 4, 3.8, 3.6, 3.5, 3.2, 3, 2.8, 2.5, 2.2, 2, and any value within any range of any two values, preferably ≤4. In the present invention, the higher the above ratio, the higher the activation energy of the silicon-based solid electrolyte, and correspondingly, the lower its ionic conductivity at 25°C.

[0050] In this invention, the ratio of ionic conductivity at 60°C to ionic conductivity at 25°C refers to the ratio of ionic conductivity at 60°C to ionic conductivity at 25°C of the silicon-based solid electrolyte.

[0051] In some embodiments of the present invention, preferably, the silicon-based solid electrolyte has an ionic conductivity at 25°C ≥ 0.01 mS / cm, for example, 0.02 mS / cm, 0.04 mS / cm, 0.05 mS / cm, 0.07 mS / cm, 0.08 mS / cm, 0.1 mS / cm, 0.15 mS / cm, 0.25 mS / cm, 0.3 mS / cm, 0.4 mS / cm, 0.5 mS / cm, 0.6 mS / cm, 0.7 mS / cm, 0.8 mS / cm, 0.9 mS / cm, 1 mS / cm, 1.2 mS / cm, 1.3 mS / cm, 1.5 mS / cm, 1.8 mS / cm, 2 mS / cm, 2.5 mS / cm, 3 mS / cm, and any value within any range of any two values, preferably ≥ 0.1 mS / cm, more preferably ≥ 1 mS / cm.

[0052] In some embodiments of the present invention, preferably, the silicon-based solid electrolyte has an ionic conductivity at 60°C ≥ 0.04 mS / cm, for example, 0.04 mS / cm, 0.06 mS / cm, 0.08 mS / cm, 0.1 mS / cm, 0.2 mS / cm, 0.25 mS / cm, 0.3 mS / cm, 0.4 mS / cm, 0.5 mS / cm, 0.6 mS / cm, 0.7 mS / cm, 0.8 mS / cm, 0.9 mS / cm, 1 mS / cm, 1.2 mS / cm, 1.5 mS / cm, 1.8 mS / cm, 2 mS / cm, and any value within any range of any two values, preferably ≥ 0.1 mS / cm, more preferably ≥ 0.3 mS / cm.

[0053] In this invention, unless otherwise specified, the ionic conductivity parameter is measured using the AC impedance method, including: clamping the sample to be tested between two stainless steel disc electrodes (SS), measuring the ionic conductivity (σ) by electrochemical impedance spectroscopy (EIS), and calculating it according to formula (1): Among them, R b The volume resistivity (R) of the sample to be tested b (Determined by impedance spectroscopy), where L and S are the thickness and area of ​​the sample to be tested.

[0054] In some embodiments of the present invention, preferably, the Push's ratio of the silicon-based solid electrolyte is ≤1.75, more preferably 1-1.75, for example, 1, 1.2, 1.3, 1.4, 1.5, 1.55, 1.6, 1.62, 1.65, 1.68, 1.7, 1.72, 1.75, and any value within the range of any two values, more preferably 1.6-1.75.

[0055] In this invention, the push ratio, used to evaluate the ductility and brittleness of a material, is the ratio of bulk modulus (B) to shear modulus (G), B / G.

[0056] In some embodiments of the present invention, preferably, the shear modulus of the silicon-based solid electrolyte is ≤30 GPa, for example, 0.1 GPa, 0.5 GPa, 0.8 GPa, 1 GPa, 2 GPa, 3 GPa, 4 GPa, 5 GPa, 6 GPa, 7 GPa, 8 GPa, 9 GPa, 10 GPa, 11 GPa, 12 GPa, 15 GPa, 20 GPa, 25 GPa, 30 GPa, and any value within the range of any two values, preferably 1-20 GPa.

[0057] In this invention, unless otherwise specified, the Push's ratio and shear modulus parameters are obtained using GB / T 7962.6-2010. Specific test conditions include: applying 360 MPa pressure using a square mold to press the solid electrolyte into a block with dimensions of 22 mm × 22 mm × 120 mm; precision grinding of both end faces to a parallelism difference of no more than 0.02 mm; and a surface roughness Ra = 0.1. The Push's ratio and shear modulus parameters of the aforementioned silicon-based solid electrolyte are then tested according to GB / T 7962.6-2010.

[0058] A second aspect of the present invention provides a method for preparing a silicon-based solid electrolyte, the method comprising: mixing raw materials and ball milling them in an inert atmosphere to obtain a silicon-based solid electrolyte having the composition shown in Formula I;

[0059] Among them, Li a Si b X x Y y(I); X is selected from at least one of the negative monovalent groups, and Y is selected from at least one of the negative divalent and / or negative trivalent groups; 1≤a≤6, 0.5≤b≤2, 0≤x≤6, 0≤y≤6, and x and y are not both 0.

[0060] In this invention, unless otherwise specified, the composition and type of the silicon-based solid electrolyte are as defined above, and will not be elaborated further here.

[0061] In this invention, unless otherwise specified, the inert atmosphere includes, but is not limited to, nitrogen atmosphere, helium atmosphere, argon atmosphere, neon atmosphere, etc., and is preferably nitrogen atmosphere.

[0062] In this invention, the mixing aims to uniformly mix the raw materials based on Formula I. Preferably, in Formula I, when x≠0 and y≠0, the raw materials are selected from Li. m X n and Si p Y q Or, Li m’ Y n’ and Si p’ X q’ Or, Li m X n Li m’ Y n’ Si p Y q Si p’ X q’ .

[0063] In this invention, preferably, in formula I, when x≠0 and y=0, the raw material is selected from Li m X n and Si p X q Or, Li m X n And Si, or Li and Si p’ X q’ .

[0064] In this invention, preferably, in formula I, when x = 0 and y ≠ 0, the raw material is selected from Li m’ Y n’ and Si p Y q Or, Li m’ Y n’ And Si, or Li and Si p Y q .

[0065] In this invention, the mixing conditions include: a temperature of 15-30°C, for example, 15°C, 20°C, 25°C, 30°C, or any value within the range of any two values, preferably 20-30°C; and a time of 0.1-5h, for example, 0.1h, 0.5h, 1h, 1.5h, 2h, 3h, 5h, or any value within the range of any two values, preferably 0.1-2h.

[0066] In this invention, the ball milling aims to convert mechanical energy into chemical energy, causing the old bonds in the raw material to break and become amorphous, forming a substance having Formula I. Preferably, the ball milling conditions include: a temperature of -20°C to 50°C, for example, -20°C, -10°C, 0°C, 5°C, 15°C, 20°C, 25°C, 30°C, 40°C, 50°C, and any value within any range of any two values, preferably 15-40°C; and a time of 20-160 hours, for example, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 80 hours, 90 hours, 100 hours, 110 hours, 120 hours, 150 hours, 160 hours, and any value within any range of any two values, preferably 80-120 hours.

[0067] In this invention, more preferably, the ball milling conditions further include: a ball-to-material ratio of 5-60:1, for example, 5:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, or any value within the range of any two values, preferably 30-50:1; and a rotational speed of 200-500 rpm, for example, 200 rpm, 250 rpm, 300 rpm, 400 rpm, 500 rpm, or any value within the range of any two values, preferably 350-500 rpm. In this invention, the ball-to-material ratio refers to the mass ratio of the grinding balls to the raw material.

[0068] In this invention, preferably, the method further includes: sequentially pressing and / or heating the ball-milled product to obtain the silicon-based solid electrolyte.

[0069] In this invention, the performance of the silicon-based solid electrolyte can be further optimized by employing pressing and / or heat treatment techniques, such as Push's ratio and shear modulus.

[0070] In this invention, the pressing conditions include: a pressure of 100-800 MPa and a time of 0.5-60 min; the heat treatment conditions include: a temperature of 100-600 °C and a time of 0.5-20 h.

[0071] A third aspect of the present invention provides an electrode, the electrode comprising: a silicon-based solid electrolyte provided in the first aspect, or a silicon-based solid electrolyte prepared by the preparation method provided in the second aspect; wherein the electrode is a positive electrode or a negative electrode.

[0072] Using the silicon-based solid electrolyte provided by this invention in electrode sheets can effectively improve the contact between the electrolyte and the active material particles, thereby increasing the conductivity of the electrode sheets.

[0073] In some embodiments of the present invention, preferably, the content of the silicon-based solid electrolyte in the electrode is 0.1-30 wt%, for example, 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 20 wt%, 30 wt%, and any value within any range of any two values, preferably 0.1-15 wt%.

[0074] In this invention, unless otherwise specified, the electrode comprises: a current collector and an active material layer loaded on the current collector, the active material layer comprising: an active material, a conductive agent, a binder, and a silicon-based solid electrolyte provided by this invention.

[0075] In one specific embodiment of the present invention, the positive electrode sheet includes: a positive current collector and a positive active material layer. The positive active material layer includes: a positive active material, a conductive agent, a binder, and a silicon-based solid electrolyte. The mass ratio of the positive active material, the conductive agent, the binder, and the silicon-based solid electrolyte is 70-99.9:0-5:0-5:0.1-30, preferably 80-95:0.1-3:0.1-3:0.1-15.

[0076] In another specific embodiment of the present invention, the negative electrode sheet includes: a negative electrode current collector and a negative electrode active material layer, wherein the negative electrode active material layer includes: a negative electrode active material, a conductive agent, a binder and a silicon-based solid electrolyte, wherein the mass ratio of the negative electrode active material, the conductive agent, the binder and the silicon-based solid electrolyte is 70-99.9:0-5:0-5:0.1-30, preferably 80-95:0.1-3:0.1-3:0.1-15.

[0077] In this invention, the positive electrode active material includes, but is not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2, abbreviated as NCM333; LiNi 0.5 Co 0.2Mn 0.3 O2, abbreviated as NCM523; LiNi 0.5 Co 0.25 Mn 0.25 O2, abbreviated as NCM211; LiNi 0.6 Co 0.2 Mn 0.2 O2, abbreviated as NCM622; LiNi 0.8 Co 0.1 Mn 0.1 O2, abbreviated as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 O2) and its modified compounds, etc.; positive current collectors include, but are not limited to, aluminum foil, etc.

[0078] In this invention, the negative electrode active material includes, but is not limited to, graphite, hard carbon, soft carbon, silicon, SiO, and Si / C; the negative electrode current collector includes, but is not limited to, copper foil.

[0079] In this invention, the conductive agent includes, but is not limited to, acetylene black, conductive carbon black, carbon fiber, carbon nanotubes, and Ketjen black.

[0080] In this invention, the adhesive includes, but is not limited to, styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), carboxymethyl chitosan (CMCS), polyamide-imide (PAI), polyethyleneimine (PEI), polyimide (PI), and tert-butyl acrylate triethoxyvinylsilane (TBATEVS).

[0081] A fourth aspect of the present invention provides an all-solid-state battery comprising a positive electrode, a negative electrode, and an electrolyte; wherein the positive electrode, the negative electrode, and the electrolyte each independently comprise a silicon-based solid electrolyte provided in the first aspect, or a silicon-based solid electrolyte prepared by the preparation method provided in the second aspect.

[0082] In this invention, unless otherwise specified, the electrolyte in the all-solid-state battery can be entirely or partially the silicon-based solid-state electrolyte provided by this invention.

[0083] The present invention will be described in detail below through embodiments.

[0084] Example 1

[0085] Weigh the raw materials Li2O and SiI4 according to the molar ratio Li:Si:I:O = 2:1:4:1;

[0086] In a nitrogen atmosphere, the above raw materials were mixed in a mortar at 25°C for 10 minutes. The resulting mixture was then transferred to a ball mill for ball milling at 25°C for 100 hours. The ball-to-material ratio was 40:1 and the rotation speed was 400 rpm. This yielded a silicon-based solid electrolyte S1 with the general formula Li2SiI4O.

[0087] Figure 1a shows the XPS diagram of the silicon-based solid electrolyte S1, where the Si 2p peak of Li2SiI4O is at 103.5 eV. Figure 1b shows the XPS diagram of the raw material SiI4, where the standard Si 2p peak of the raw material SiI4 is at 102.5 eV. This indicates that the coordination environment of Si element in silicon-based solid electrolyte S1 has changed compared with that of raw material SiI4, and new bonds have been generated.

[0088] Figure 2 shows the EIS diagram of the silicon-based solid electrolyte S1. The ionic conductivity of the silicon-based solid electrolyte S1 at 25℃ is 0.12 mS / cm, and the ionic conductivity at 60℃ is 0.41 mS / cm.

[0089] Compared to Figures 3b and 3c, which show the XRD patterns of raw material SiI4 and raw material Li2O respectively, the XRD pattern of the silicon-based solid electrolyte S1 is shown in Figure 3a. The degree of crystallinity is greatly reduced and the degree of amorphization is increased, proving that most of the raw materials have reacted to form an amorphous solid electrolyte.

[0090] Example 2

[0091] Weigh the raw materials LiI and SiO2 according to the molar ratio Li:Si:I:O = 2:1:2:2;

[0092] In a nitrogen atmosphere, the above raw materials were mixed at 25°C for 0.5 h. The resulting mixture was then transferred to a ball mill for ball milling at 25°C for 100 h, with a ball-to-material ratio of 40:1 and a rotation speed of 400 rpm, to obtain silicon-based solid electrolyte S2, with the general formula Li2SiI2O2.

[0093] Example 3

[0094] Weigh the raw materials LiI and SiI4 according to the molar ratio Li:Si:I = 2:1:6;

[0095] In a nitrogen atmosphere, the above raw materials were mixed at 25°C for 0.5 h. The resulting mixture was then transferred to a ball mill for ball milling at 25°C for 100 h, with a ball-to-material ratio of 40:1 and a rotation speed of 400 rpm, to obtain silicon-based solid electrolyte S3, with the general formula Li2SiI6.

[0096] Example 4

[0097] According to the molar ratio Li:Si:I:Cl:O=2:1:4:1:0.5, weigh out the raw materials Li2O, SiI4, and SiCl4;

[0098] In a nitrogen atmosphere, the above raw materials were mixed in a mortar at 25°C for 10 minutes. The resulting mixture was then transferred to a ball mill for ball milling at 25°C for 100 hours, with a ball-to-material ratio of 40:1 and a rotation speed of 400 rpm, to obtain a silicon-based solid electrolyte S4 with the general formula Li2SiI4ClO. 0.5 .

[0099] Example 5

[0100] According to the molar ratio Li:Si:I:Br:O=2:1:4:1:0.5, weigh out the raw materials Li2O, SiI4, and SiBr4;

[0101] In a nitrogen atmosphere, the above raw materials were mixed in a mortar at 25°C for 10 minutes. The resulting mixture was then transferred to a ball mill for ball milling at 25°C for 100 hours, with a ball-to-material ratio of 40:1 and a rotation speed of 400 rpm, to obtain the silicon-based solid electrolyte S5, with the general formula Li₂SiI₄BrO. 0.5 .

[0102] Example 6

[0103] Weigh out the raw materials Li2O, SiI4, and SiBr4 according to the molar ratio Li:Si:I:Br:O = 2:1:2:2:1;

[0104] In a nitrogen atmosphere, the above raw materials were mixed in a mortar at 25°C for 10 minutes. The resulting mixture was then transferred to a ball mill for ball milling at 25°C for 100 hours. The ball-to-material ratio was 40:1, and the rotation speed was 400 rpm. This yielded a silicon-based solid electrolyte S6 with the general formula Li2SiI2Br2O.

[0105] Example 7

[0106] Weigh the raw materials Li2O, SiI4, and SiCl4 according to the molar ratio Li:Si:I:Cl:O = 2:1:2:2:1;

[0107] In a nitrogen atmosphere, the above raw materials were mixed in a mortar at 25°C for 10 minutes. The resulting mixture was then transferred to a ball mill for ball milling at 25°C for 100 hours. The ball-to-material ratio was 40:1, and the rotation speed was 400 rpm. This yielded a silicon-based solid electrolyte S7 with the general formula Li2SiI2Cl2O.

[0108] Example 8

[0109] Weigh out the raw materials Li3P and SiI4 according to the molar ratio Li:Si:I:P = 3:1:4:1;

[0110] In a nitrogen atmosphere, the above raw materials were mixed in a mortar at 25°C for 10 minutes. The resulting mixture was then transferred to a ball mill for ball milling at 25°C for 100 hours. The ball-to-material ratio was 40:1, and the rotation speed was 400 rpm. This yielded a silicon-based solid electrolyte S8 with the general formula Li3SiI4P.

[0111] Example 9

[0112] The method is the same as in Example 1, except that...

[0113] Replace the ball milling time with 30 hours;

[0114] Under the same conditions, silicon-based solid electrolyte S9 was obtained, with the general formula Li2SiI4O.

[0115] Example 10

[0116] The method is the same as in Example 1, except that...

[0117] The ball-milled product was pressed at a pressure of 370 MPa for 30 min.

[0118] Under the same conditions, a silicon-based solid electrolyte S10 with the general formula Li2SiI4O was obtained.

[0119] Comparative Example 1

[0120] Weigh out the raw materials Li2O and GeI4 according to the molar ratio Li:Ge:I:O = 2:1:4:1;

[0121] In a nitrogen atmosphere, the above raw materials were mixed in a mortar at 25°C for 10 minutes. The resulting mixture was then transferred to a ball mill for ball milling at 25°C for 100 hours, with a ball-to-material ratio of 40:1 and a rotation speed of 400 rpm, to obtain a silicon-based solid electrolyte DS1 with the general formula Li₂GeI₄O. Its Push's ratio was 1.60, and its ionic conductivity could not be measured.

[0122] Comparative Example 2

[0123] The method is the same as in Example 1, except that...

[0124] The above mixture was manually ground using a mortar and pestle at a temperature of 25°C for 4 hours.

[0125] Under the same conditions, a solid electrolyte DS2, a mixture of Li2O and SiI4, was obtained.

[0126] Table 1

[0127] Note: " / " indicates that no measurement was taken.

[0128] As can be seen from the results in Table 1, compared with Comparative Examples 1-2, Examples 1-10 using the silicon-based solid electrolyte provided by this invention not only have Li a Si b X x Y y The composition shown also exhibits high ionic conductivity and a low Push's ratio. In particular, the performance of the silicon-based solid electrolyte can be controlled by adjusting the types and subscripts of X and Y in the electrolyte.

[0129] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A silicon-based solid electrolyte, characterized in that, Having the composition shown in Formula I, Li a Si b X x Y y (I); wherein X is selected from at least one of the negative monovalent groups, and Y is selected from at least one of the negative divalent and / or negative trivalent groups; 1≤a≤6, 0.5≤b≤2, 0≤x≤6, 0≤y≤6, and x and y are not simultaneously 0.

2. The silicon-based solid electrolyte according to claim 1, wherein, In formula I, X is selected from F - Cl - ,Br - I - CN - OCN - SCN- and N3 - At least one of them; And / or, Y is selected from O 2- S 2- Se 2- Te 2- N 3- P 3- As 3- Sb 3- and Bi 3- At least one of them.

3. The silicon-based solid electrolyte according to claim 1 or 2, wherein, In formula I, X is selected from F - Cl - ,Br - and I - At least one of them, preferably Cl - ,Br - and I - At least one of them; And / or, Y is selected from O 2- S 2- N 3- and P 3- At least one of them, preferably O 2- and / or P 3- .

4. The silicon-based solid electrolyte according to any one of claims 1-3, wherein, In formula I, a / b = 0.5-6, preferably 1.5-3; And / or, x / (x+y) = 0.5-1, preferably 0.8-1; And / or, b / (x+y) = 1:7-1:1, preferably 1:6-1:4; And / or, 1≤a≤3, 1≤b≤2, 1≤x≤6, 0.5≤y≤2.

5. The silicon-based solid electrolyte according to any one of claims 1-4, wherein, As stated above, the silicon base solid state is selected by Li2SiI4O, Li2SiI6, Li2SiCl6, Li2SiI4ClO. 0.5 Li2SiI4BrO 0.5 、Li2SiCl4O、Li2SiBr6、Li2SiBr4O、Li2SiI2Br2O、Li2SiI2Cl2O、Li2SiI2O2、Li2SiBr2O2、Li2SiCl2O2、Li2Si 0.8 I 3.2 O, Li2Si 0.6 I 2.4 O, Li2Si 0.8 Cl 3.2 O, Li2Si 0.8 Br 3.2 O, Li2Si 0.6 Cl 2.4 O, Li2Si 0.6 Br 2.4 O, Li2SiI4S, Li2SiBr4S, Li2SiCl4S, Li2SiS, Li2SiCl3N, Li2SiCl3P and Li2SiI3P medium; And / or, the silicon-based solid electrolyte is selected from Li₂SiI₄O, Li₂SiBr₄O, Li₂SiCl₄O, Li₂SiI₂O₂, Li₂SiBr₂O₂, Li₂SiCl₂O₂, Li₂Si 0.8 I 3.2 O, Li2Si 0.8 Br 3.2 O, Li2Si 0.8 Cl 3.2 O, Li2Si 0.6 I 2.4 O, Li2Si 0.6 Br 2.4 O and Li2Si 0.6 Cl 2.4 At least one of O; And / or, the silicon-based solid electrolyte is prepared by ball milling raw materials based on the elemental ratio of Formula I in an inert atmosphere.

6. The silicon-based solid electrolyte according to any one of claims 1-5, wherein, The silicon-based solid electrolyte satisfies the following condition: the ratio of ionic conductivity at 60℃ to ionic conductivity at 25℃ is ≤6, preferably ≤4; And / or, the silicon-based solid electrolyte has an ionic conductivity at 25°C of ≥0.01 mS / cm, preferably ≥0.1 mS / cm, and more preferably ≥1 mS / cm; And / or, the silicon-based solid electrolyte has an ionic conductivity at 60°C of ≥0.04 mS / cm, preferably ≥0.1 mS / cm, and more preferably ≥0.3 mS / cm; And / or, the Push's ratio of the silicon-based solid electrolyte is ≤1.75, preferably 1-1.75, more preferably 1.6-1.75; And / or, the shear modulus of the silicon-based solid electrolyte is ≤30GPa, preferably 1-20GPa.

7. A method for preparing a silicon-based solid electrolyte, characterized in that, The preparation method includes: mixing raw materials and ball milling them in an inert atmosphere to obtain a silicon-based solid electrolyte having the composition shown in Formula I; Among them, Li a Si b X x Y y (I); wherein X is selected from at least one of the negative monovalent groups, and Y is selected from at least one of the negative divalent groups and / or negative trivalent groups; 1≤a≤6, 0.5≤b≤2, 0≤x≤6, 0≤y≤6, and x and y are not simultaneously 0.

8. The preparation method according to claim 7, wherein, The conditions for ball milling include: a temperature of -20°C to 50°C, preferably 15-40°C; and a time of 20-160 hours, preferably 80-120 hours. And / or, the ball milling conditions further include: a ball-to-material ratio of 5-60:1, preferably 30-50:1; and a rotational speed of 200-500 rpm, preferably 350-500 rpm. And / or, the method further includes: sequentially pressing and / or heating the ball-milled product to obtain the silicon-based solid electrolyte.

9. An electrode sheet, characterized in that, The electrode comprises: a silicon-based solid electrolyte as described in any one of claims 1-6, or a silicon-based solid electrolyte prepared by the preparation method described in claim 7 or 8; wherein the electrode is a positive electrode or a negative electrode.

10. An all-solid-state battery, characterized in that, The all-solid-state battery contains a positive electrode, a negative electrode, and an electrolyte; The positive electrode, negative electrode, and electrolyte each independently contain the silicon-based solid electrolyte as described in any one of claims 1-6, or the silicon-based solid electrolyte prepared by the preparation method described in claim 7 or 8.

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