Solid electrolyte and preparation method therefor, and battery

Abstract

The present invention belongs to the technical field of battery materials, and relates to a solid electrolyte and a preparation method therefor, and a battery. The solid electrolyte comprises a carrier salt CaNb and a Van der Waals crystal MB y having a Van der Waals crystal structure; some of the anion donors of N in the CaNb are replaced with some of the elements B in the compound having a Van der Waals crystal structure, such that the carrier salt and the compound having a Van der Waals crystal structure form a framework structure; the dissociated cation donors of C are filled into the gap of the frame structure, some of which act as carriers for transmission in the frame structure, and the others of which form a nanocrystalline with MBy or B. In the electrolyte, the Van der Waals crystal MBy acts as a solid solvent, and can dissociate a plurality of salts CaNb and form a solid electrolyte; and functionalized solid electrolytes are developed, including a solid electrolyte having a high air stability, a solid electrolyte capable of matching a Li metal negative electrode, and a solid electrolyte that supports an extremely low temperature and high rate.

Description

A solid electrolyte, its preparation method, and a battery Technical Field

[0001] This invention belongs to the field of battery materials technology, and relates to a solid electrolyte, its preparation method, and a battery. Background Technology

[0002] All-solid-state batteries have become the most promising next-generation energy storage technology due to their high energy density and high safety. The development of batteries with high ionic conductivity (>1×10⁻⁶) is underway. -3 Scm -1 Wide electrochemical stability window (>4 V vs Li) + Inorganic solid-state electrolytes (such as those with good processing and molding properties and controllable cost) are key to the practical application of all-solid-state batteries. The inorganic solid-state electrolyte systems disclosed in relevant technical literature can be divided into oxide material systems, sulfide material systems, and halide material systems. These material systems have different characteristic crystal structures, and the conductive ions are transported along lattice channels with relatively low and gradual migration activation energies. However, each of these material systems has some bottleneck problems.

[0003] Traditional liquid-ion battery technology widely employs electrolyte (liquid) engineering strategies, using different solvents, additives, and metal salts to design electrolyte compositions. This allows for targeted improvements in low-temperature performance and flammability, as well as control over solvation junctions and the composition of the resulting solid electrolyte interphase (SEI), thereby developing functionalized electrolytes. However, electrolyte (liquid) engineering strategies are difficult to apply to solid-state electrolyte development. This is because ion transport in solid-state electrolytes often depends on specific crystal structures, such as layered halides like Li3InCl6 (patent document: CN 111916820 A) and halides like Li with a UCl3-type lattice. 0.388 Ta 0.238 La 0.475 Cl3 (patent document: CN 113772729 A), etc.; therefore, the electrolyte composition can only be controlled through doping and substitution, and it is not possible to flexibly introduce beneficial elements. Moreover, the dopant ions need to have similar ionic radii and valence states to the ions at the target lattice sites, which limits the range of options.

[0004] Furthermore, during the cycling process of liquid batteries, although some organic electrolyte decomposes on the electrode surface and forms an electrolyte interphase (SEI), the ionic conductivity of the remaining electrolyte remains unaffected and can still wet the electrode surface through the gaps in the SEI film. However, in all-solid-state batteries, the decomposition of the solid electrolyte on the electrode surface disrupts its ion transport channels, significantly reducing ionic conductivity and causing a sharp increase in electrolyte / electrode interface impedance, becoming a significant factor in battery performance degradation and failure. Therefore, strategies to control the SEI through electrolyte engineering design of solid electrolyte composition remain difficult to implement. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a solid electrolyte, its preparation method, and a battery, thereby improving ionic conductivity. The synthesis route is simple, the raw material cost is low, and it has good electrochemical performance.

[0006] This invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a solid electrolyte with the general formula (C a N b ) x- MB y ;

[0008] Among them, MB y Using van der Waals crystals as the structural framework, y represents the number of atoms of element B; C a N b Let a and b be the number of cation donor C and anion donor N atoms in the carrier salt, respectively; x is the number of C atoms. a N b and MB y stoichiometry;

[0009] The anion donor N partially replaces MB. y The B site in the structure forms a framework with carrier ion migration channels.

[0010] Preferably, the van der Waals crystal is one or more of halide van der Waals crystals, sulfide van der Waals crystals, and oxide van der Waals crystals;

[0011] The MB y M is one or more of Zr, Hf, Ta, Nb, Al, Fe, Ga, In, Mo, W, Y, Ti, Si, B, and Sb; B is one or more of F, Cl, Br, I, S, or O.

[0012] Preferably, the anion donor N comprises polyanion XO. m n- Polyanionic derivative group X m O 3m+1 n- Or simple anions;

[0013] The simple anion is a halogen or OH-. - NH2 - O2 2- O 2- S 2- or N 3- One or more of the following;

[0014] The polyanion XO m n- Or the derivatized group X of the polyanion m O 3m+1 n- In this context, X is one or more of B, S, P, Si, As, Mo, W, or C; m is 2-4; and n is the charge number.

[0015] Preferably, the anion donor N is a polyanion XO. m n- Or the derivatized group X of the polyanion m O 3m+1 n- The MB y B element XO m n- or X m O 3m+1 n- replace.

[0016] Preferably, the cation donor C is Li. + Na + Ag + Cu + or K + Among them, Li + The coordination number ranges from 3 to 5, Na + The coordination number ranges from 7 to 9.

[0017] Preferably, a portion of the dissociated cation donor C is transported within the framework structure as a charge carrier, while another portion interacts with MB. y Or B forms nanocrystals; wherein the content of nanocrystals in the solid electrolyte is <30 wt.%;

[0018] The nanocrystals include C e MB f and CB, where C e MB f In the figure, e and f are the stoichiometric coefficients of the cation donors C and MB, respectively; the content of nanocrystals in the solid electrolyte is <30 wt.%.

[0019] In the framework structure, (C a N b ) x- MB y It is granular, C e MB f Alternatively, CB may adhere to the surface of the particles, which are amorphous phases, while nanocrystals are crystalline phases.

[0020] Preferably, the solid electrolyte (C) a N b) x- MB y It has an amorphous or nearly amorphous structure, with x ranging from 0.2 to 2 and y ranging from 3 to 6.

[0021] The range of x is 0.2 to 2, and the range of y is 3 to 6;

[0022] Secondly, the present invention provides a method for preparing a solid electrolyte, comprising the following steps:

[0023] Under an anhydrous and oxygen-free inert atmosphere, C is added according to stoichiometric ratio. a N b and MB y Solid-phase reaction occurs through mechanical ball milling to obtain a solid electrolyte (C). a N b ) x- MB y .

[0024] Preferably, the control parameters of the mechanical ball milling method include: the diameter of the grinding balls is 3 mm to 10 mm; the mass ratio of the grinding balls to the total raw material is 60:1 to 20:1; the grinding time is 1 h to 30 h; and the ball mill speed is 400 r / min to 800 r / min.

[0025] Thirdly, the present invention provides a battery comprising the aforementioned solid electrolyte.

[0026] Compared with the prior art, the present invention has the following beneficial technical effects:

[0027] The solid electrolyte provided in this application comprises a carrier salt C. a N b and van der Waals crystals MB with van der Waals crystal structure y Composition, C a N b In this process, some of the anion donor N replaces some of the B element in the compound with a van der Waals crystal structure, resulting in a framework structure formed by the carrier salt and the compound with the van der Waals crystal structure. Because some of the anion donor N replaces some of the B element in the carrier salt, some of the cation donor C is dissociated and released. Part of the released cation C acts as a charge carrier within the framework structure, while the other part interacts with MB. y Alternatively, part B may form nanocrystals. In this electrolyte, van der Waals crystals (MB) y It acts as a solid solvent and can dissociate various salts C a N bThis solid-solid electrolyte, with its universality, facilitates the expansion of electrolyte systems. It also enables solid-state electrolyte engineering, leading to the development of functionalized solid-state electrolytes, including those with high air stability, those compatible with Li metal anodes, and those supporting extremely low temperatures and high rates.

[0028] Furthermore, the open framework structure, formed by connecting charge carrier salts and van der Waals crystals, possesses a cross-linked network backbone and penetrating three-dimensional channels, with cation donor C filling the vacancies within. This structure has a large free volume, and the hopping transport of cation donor C within it is less repelled by the framework cations, resulting in high ionic conductivity. In addition, due to the easy deformation of the cross-linked network backbone, this material exhibits good processing and molding performance, requiring no high-temperature conditions. During cold pressing, it easily forms dense electrolyte sheets, resulting in good electrical contact between particles and low interfacial resistance. It possesses amorphous properties, is not dependent on specific crystal structures and elemental compositions, has a wide range of compositional control, and allows for the doping of various beneficial ions.

[0029] Furthermore, the material system provided in this application embodiment has high ionic conductivity, high oxidation limit, and a wide range of adjustable composition; and the synthesis technology route is simple. The all-solid-state battery based on this electrolyte material system can achieve fast charging and operate at low temperatures.

[0030] Furthermore, the solid electrolyte provided in this application has high ionic conductivity, a simple synthesis route, low raw material cost, and good electrochemical performance.

[0031] Furthermore, the preparation method provided in this application is simple, has a short cycle, does not involve high temperature or vacuum sintering operations, does not generate irritating gases, and can significantly reduce energy consumption and environmental pollution. Attached Figure Description

[0032] Figure 1 is an open framework structure diagram of the Li2O-ZrCl4 solid electrolyte provided in Example 1 of the present invention.

[0033] Figure 2 shows the electrochemical impedance spectroscopy (EIS) of the halide solid electrolytes provided in the embodiments of this application. In the figure, the horizontal axis represents the real resistance in ohms (Ω), and the vertical axis represents the imaginary resistance in ohms (Ω). Among them, Figure (a) shows the EIS of Li2O-ZrCl4, Li2S-ZrCl4, Li3N-ZrCl4 and the halide solid electrolyte Li2ZrCl6 provided in Comparative Example 1. In the figure, spectral lines a, b, c and d represent Li2O-ZrCl4, Li2S-ZrCl4, Li3N-ZrCl4 and Li2ZrCl6, respectively. Figure (b) shows the EIS of Na2S-ZrCl4. Figure (c) shows the EIS of Ag2O@-ZrCl4.

[0034] Figure 3 shows the fine X-ray absorption spectra of Li2SO4-ZrCl4, Li3PO4-ZrCl4, and Li2CO3-ZrCl electrolytes provided in the embodiments of the present invention. In the figure, the horizontal axis "R" represents distance; the vertical axis "FT" represents k. 3 The weighted extended X-ray fine structure is obtained by Fourier transform. In Figure (a), it is Li2SO4-ZrCl4, in Figure (b), it is Li3PO4-ZrCl4, and in Figure (c), it is Li2CO3-ZrCl.

[0035] Figure 4 shows the pair distribution function of the Li2SO4-ZrCl4 solid electrolyte provided in the embodiments of the present invention. In the figure, the horizontal axis “r” represents distance; the vertical axis “G” represents the pair distribution function. Among them, Figure (a) is Li2O-ZrCl4, Figure (b) is Li2SO4-ZrCl4, Figure (c) is Li3PO4-ZrCl4, and Figure (d) is Li2CO3-ZrCl4.

[0036] Figure 5 shows the X-ray diffraction patterns of the lithium salt-van der Waals solid electrolytes Li₂CO₃-HfCl₄, Li₂SO₄-HfCl₄, Li₂CO₃-ZrCl₄, Li₂SO₄-ZrCl₄, Li₂O-TaCl₅, 2 / 3Li₃PO₄-ZrCl₄, and Li₂C₂O₄-TaCl₅ in the embodiments of the present invention. In the figure, the horizontal axis represents the diffraction angle (2 Theta), in degrees (°); the vertical axis represents the diffraction intensity.

[0037] Figure 6 shows the X-ray diffraction patterns of the solid electrolyte Li2O-ZrCl4 prepared by different ball milling times in Example 1 of this invention. In the figure, the horizontal axis represents the diffraction angle (2 Theta), in degrees (°); the vertical axis represents the diffraction intensity.

[0038] Figure 7 is a high-resolution cryo-transmission electron microscope image of the solid electrolyte (Li2SO4) ZrCl4 prepared in the embodiments of this application. In the figure, the nanocrystals are LiCl, and the lower right corner image shows diffraction spots.

[0039] Figure 8 shows the linear scan curves of the solid electrolytes Li2O-ZrCl4 and Li3PO4-ZrCl4 provided in the embodiments of this application, and the solid electrolyte Li2ZrCl6 provided in Comparative Example 1. The horizontal axis represents voltage in volts (V); the vertical axis represents current density in milliamperes per gram (mAg). -1 ).

[0040] Figure 9 shows the electrochemical performance of the all-solid-state lithium battery assembled in Application Example 1 of this application at a 2C rate for the first 100 cycles. In the figure, the horizontal axis represents the number of cycles; the left vertical axis represents the specific capacity, in milliampere-hours per gram (mAhg).-1 The right-hand vertical axis represents the Coulomb efficiency.

[0041] Figure 10 shows the electrochemical performance of the all-solid-state lithium battery assembled in Application Example 2 of this application at 5 C rate for the first 100 cycles. In the figure, the horizontal axis represents the number of cycles; the left vertical axis represents the specific capacity, in milliampere-hours per gram (mAhg). -1 The right-hand vertical axis represents the Coulomb efficiency.

[0042] Figure 11 shows the electrochemical performance of the all-solid-state lithium battery assembled in Application Example 3 of this application at -30 °C for the first 150 cycles. In the figure, the horizontal axis represents the number of cycles; the left vertical axis represents the specific capacity, in milliampere-hours per gram (mAhg). -1 The right-hand vertical axis represents the Coulomb efficiency.

[0043] Figure 12 shows the solid electrolytes with a low coordination number lithium environment in Examples 33, 30, 34 and 2 of the present invention. 7 Li solid-state NMR spectrum.

[0044] Figure 13 shows the solid electrolyte of Embodiment 22 of the present invention. 23 Na solid NMR spectrum. Embodiments of the present invention

[0045] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0046] A solid electrolyte with the general formula (C a N b ) x- MB y Among them, MB y Using van der Waals crystals as the structural framework, y represents the number of atoms of element B; C a N b Let a and b be the number of cation donor C and anion donor N atoms in the carrier salt, respectively; x is the number of C atoms. a N b and MB y stoichiometry;

[0047] The anion donor N partially replaces MB. y The B site forms a framework structure with carrier ion migration channels; the dissociated cation donor C fills the voids in the framework structure, interacting with MB. y Or B forms nanocrystals, i.e., C e MB f And CB, but C and MB yThe force exerted by A or B is relatively weak, enabling C to shuttle and migrate within a relatively large three-dimensional framework, resulting in a high mobility of the cation donor C within this framework structure and exhibiting high room-temperature ionic conductivity.

[0048] Among them, 0.2 < x < 2, y is from 3 to 6, and x is the mixing molar ratio of C y when the amount of MB is 1 mole. a N b and MB y mixed molar ratio.

[0049] Exemplarily, C a N b can be: Li2O, Li2S, Li3N, LiOH, Li3N, Li2O2, LiBO2, Li4SiO4, Li2MoO3, Li2CO3, Li3PO4, Li2SO4, Li2SiO3, Li2C2O4, Na2O, Na2S, Na3N, NaOH, Na3N, Na2O2, NaBO2, Na4SiO4, Na2MoO3, Na2CO3, Na3PO4, Na2SO4, K2O, K2S, K3N, KOH, K2O2, KBO2, K4SiO4, K2MoO3, K2CO3, K3PO4, K2SO4, Ag2O, Ag2S, Ag3N, AgOH, Ag3N, Ag2O2, AgBO2, Ag4SiO4, Ag2MoO3, Ag2CO3, Ag3PO4, Ag2SO4.

[0050] MB y is a van der Waals crystal, and the van der Waals crystal is a compound with a van der Waals crystal structure. In some embodiments of the present invention, MB y is one or more of halide van der Waals crystals, sulfide van der Waals crystals, and oxide van der Waals crystal materials.

[0051] Preferably, M is one or more of Zr, Hf, Ta, Nb, Al, Fe, Ga, In, Mo, W, Y, Ti or V; B is one or more of halogens, S or O, and MB y can also be one or more of SiI4, BI3, SbI3.

[0052] Exemplarily, MB y can be ZrCl4, HfCl4, TaCl5, NbCl5, AlCl3, FeCl3, GaCl3, InCl3, YCl3, MoCl5, MoCl6, WCl6, SiI4, BI3, SbI3, NbOCl3, AlOCl, WOCl4, TiOCl, VOCl.

[0053] Van der Waals crystals, also known as inorganic molecular crystals, are formed by the stacking of zero-dimensional, one-dimensional, or two-dimensional structural units under the influence of van der Waals forces (intermolecular forces). y The structural units of van der Waals crystals include zero-dimensional [MB] y Polyhedra (e.g., the [SiI4] tetrahedron in SiI4 van der Waals crystals) and their dimers / polymers (e.g., the [TaCl5]2 dimer in TaCl5 van der Waals crystals), composed of [MB y One-dimensional chain polymers formed by polyhedra sharing common edges [MB] y ] n (e.g., [ZrCl4] in ZrCl4 van der Waals crystals) n (chain) and by [MB y Two-dimensional layered polymers formed by polyhedra sharing common edges [MB] y ] n (e.g., [AlCl3] in AlCl3 van der Waals crystals) n layer);

[0054] In this invention, van der Waals crystal MB y For C a N b The dissociation ability is partly due to van der Waals crystals (MB). y It possesses a characteristic structure with structural units connected by van der Waals forces, similar to the solvent in a liquid electrolyte. These van der Waals forces are easily broken under the influence of mechanical energy, providing favorable solid-phase diffusion conditions, which is conducive to [MB] y ] (or [MB) y ] n Structural building blocks and salt C a N b Atomic-level contacts are formed; on the other hand, due to the M cations in its structural units and the salt C a N b The N anions exhibit strong interactions, similar to solvation in liquid electrolytes, thus achieving C a N b The deconstruction and reconstruction of C and N in the middle.

[0055] In this invention, solid electrolyte (C a N b ) x- MB y It exhibits an amorphous or near-amorphous morphological structure. In some embodiments, the solid electrolyte comprises a nanocrystalline phase, specifically C. e MB f One or more of the following components—CB or residual raw material phases—are embedded in an amorphous matrix or distributed on the particle surface. Solid electrolyte (C a A b ) x -MBy Macroscopically, it appears as granules with a small amount of nanocrystalline phase on the surface, with a nanocrystalline phase content of <30 wt.%. By controlling the composition and size of the nanocrystalline phase, the air stability of the material can be improved, and the grain boundary electronic conductivity after cold pressing of the powder can be reduced. In the process of preparing solid electrolytes using mechanical ball milling, C e MB f It first appears and gradually decreases, accompanied by the formation of C ions. Furthermore, C ions are mainly conducted in the amorphous matrix and have high room temperature ionic conductivity.

[0056] A method for preparing a solid electrolyte includes the following steps: under an anhydrous and oxygen-free inert atmosphere, C is added according to a stoichiometric ratio. a N b and MB y Solid-phase reaction occurs through mechanical ball milling to obtain a solid electrolyte (C). a N b ) x- MB y .

[0057] The control parameters for the mechanical ball milling method include: the diameter of the grinding balls is 3 mm to 10 mm; the mass ratio of grinding balls to raw materials is 60:1 to 20:1; the milling time is 1 h to 30 h; and the mill speed is 400 r / min to 800 r / min. During the mechanical ball milling process, it is necessary to effectively cool the milling tank to prevent the tank temperature from becoming too high. Preferably, a circulating water cooling method is used.

[0058] In some embodiments of the present invention, the anhydrous and oxygen-free inert atmosphere is N2 or Ar, preferably Ar.

[0059] In some embodiments of the present invention, the grinding balls have a diameter of 3 mm to 10 mm. In specific examples, the grinding balls have a diameter of 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm, etc.

[0060] In some embodiments of the present invention, the material-to-ball ratio is 60:1 to 20:1. In specific examples, the material-to-ball ratio is 60:1, 50:1, 40:1, 30:1, or 20:1, etc.

[0061] In some embodiments of the present invention, the ball milling time is 1 h to 30 h. In specific examples, the ball milling time is 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 20 h or 30 h, etc.

[0062] In some embodiments of the present invention, the ball mill speed is 400 r / min to 800 r / min. In specific examples, the ball mill speed is 400 r / min, 500 r / min, 600 r / min, 700 r / min or 800 r / min, etc.

[0063] It should be noted that excessively long ball milling time or excessively high ball milling speed may lead to the formation of CB crystal phase and a decrease in ionic conductivity. By adjusting the ball milling parameters, it is possible to obtain a solid electrolyte with the highest ionic conductivity or an electronically insulating and air-stable solid electrolyte containing a small amount of nanocrystals.

[0064] In the preparation of solid electrolytes using the above method, the relative proportions of the amorphous and crystalline phases, as well as the composition of the crystalline phase, are controlled by the synthesis conditions, including ball milling parameters (milling time, rotation speed), raw material ratio, annealing conditions, etc. During the ball milling process, the residual crystalline phase of the raw material decreases until it disappears, accompanied by C... e MB f Nanocrystals appear. Crystal phase C e MB f The M content gradually decreases, eventually evolving into CB. By optimizing the ball milling parameters, the composition and ionic conductivity of the amorphous solid solution electrolyte can be controlled. During the ball milling preparation of Li₂O-ZrCl₄, when the ball milling speed is 600 rpm and the ball milling time is 20 h, the obtained product has fewer crystalline phases, and the ionic conductivity is the highest at 3.0 × 10⁻⁶. -3 Scm -1 When the ball milling time is 15 h, the crystalline phase of the obtained product is Li₂ZrCl₆; when the ball milling time is 80 h, the crystalline phase of the obtained product is LiCl. For example, during the ball milling preparation of Li₂O-ZrCl₄, the crystalline phase gradually evolves from Li₂O to Li₂ZrCl₆, and finally to LiCl. The evolution of the X-ray diffraction pattern is shown in Figure 6. Because nanocrystals with high Li content and low Zr content have a larger electronic band gap and lower electronic conductivity, their reactivity with water molecules in humid air is weaker (better air stability). Therefore, by controlling the proportion and composition of nanocrystals, the air stability and the grain boundary electronic conductivity after cold pressing of the powder can be optimized.

[0065] In some embodiments, the battery is an all-solid-state battery, including a positive electrode, a negative electrode, and a solid electrolyte sheet located between the positive and negative electrodes. The solid electrolyte sheet is obtained by cold pressing a solid electrolyte. The solid electrolyte is the solid electrolyte described above or a solid electrolyte prepared by the method described above.

[0066] In some embodiments, the types of batteries include lithium-ion batteries, sodium-ion batteries, potassium-ion batteries, silver-ion batteries, or copper-ion batteries.

[0067] In some embodiments, the positive electrode sheet is obtained by cold pressing or coating of a positive electrode active material and a positive electrode filler. The positive electrode active material includes, but is not limited to, at least one of cobalt aluminum oxide, lithium iron phosphate, lithium-rich phase lithium manganese oxide, and lithiated layered oxides, lithiated layered sulfides, and at least one of sodium-treated layered oxides, polyanionic compounds, and Prussian blue compounds. The positive electrode filler is at least one of an ion-conducting agent, a conductive agent, and a binder; the ion-conducting agent and the solid electrolyte between the positive and negative electrodes are of the same material; the conductive agent may include at least one of graphite, carbon black, acetylene black, Ketjen black, and carbon fiber; the binder may include at least one of, for example, styrene-butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. Cold pressing or coating methods are common methods for preparing positive electrode sheets in the art.

[0068] The negative electrode sheet is obtained by cold pressing or coating of negative electrode active material and negative electrode filler. The negative electrode active material refers to the material capable of storing and releasing Li. + Or Na + The materials used for the negative electrode include, but are not limited to, metallic materials, graphite, and silicon; the metallic materials can be elemental metals or alloys; when using metallic materials as the negative electrode active material, a negative electrode filler may not be required. The negative electrode filler is at least one of an ion-conducting agent, a conductive agent, and a binder; the ion-conducting agent and the solid electrolyte between the positive and negative electrodes of the battery are made of the same material; the conductive agent may include at least one of graphite, carbon black, acetylene black, Ketjen black, and carbon fiber; the binder may include at least one of, for example, styrene-butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. Cold pressing or coating methods are common methods for preparing negative electrode sheets in this field.

[0069] The following description, in conjunction with specific embodiments, provides further details.

[0070] Example 1

[0071] This embodiment provides a solid electrolyte Li2O-ZrCl4, and the specific preparation method is shown below:

[0072] In an anhydrous and oxygen-free argon atmosphere glove box, Li2O and ZrCl4 were mixed at a molar ratio of 1:1 and hand-ground for 10 minutes using an agate mortar to ensure thorough mixing.

[0073] The mixed powder (2 g) was transferred to a 75 mL ball mill jar, and 60 g of 3 mm diameter grinding beads were added accordingly. The ball mill jar was then evacuated and sealed. It was ball milled at 550 rpm for 20 h in a planetary ball mill, with the jar cooled by circulating water during the milling process. After milling was complete, the jar was transferred to a glove box, opened, and the powder inside was removed; this was the synthesized Li₂O-ZrCl₄ solid electrolyte.

[0074] Following the steps described above, solid electrolytes of Examples 1-37 were synthesized respectively, with the difference being that the raw materials and preparation process were adapted and adjusted, as shown in Table 1;

[0075] Table 1 shows the raw materials and reaction conditions for preparing solid electrolytes from different substances in Examples 1-34;

[0076]

[0077] Example 35

[0078] This embodiment provides a solid electrolyte (Li3PO4). 2 / 3 (AlCl3) 1 / 5 (ZrCl4) 1 / 5 (HfCl4) 1 / 5 (TaCl5) 1 / 5 (NbCl5) 1 / 5 Specifically, the preparation method provided in Example 1 is followed, except that the raw materials and their amounts are replaced with Li3PO4, AlCl3, ZrCl4, HfCl4, TaCl5, and NbCl5 mixed in a molar ratio of 2 / 3:1 / 5:1 / 5:1 / 5:1 / 5:1 / 5, the mass of the mixed powder is 40g, and the ball milling time is 2h.

[0079] Example 36

[0080] This embodiment provides a solid electrolyte (Li3PO4)(InCl3). 0.2 ZrCl4. Specifically, the preparation method provided in Example 1 is followed, except that the raw materials and their amounts are replaced with Li3PO4, InCl3, and ZrCl4 mixed in a molar ratio of 1:0.2:1, the mass of the mixed powder is 40g, and the ball milling time is 3h;

[0081] Example 37

[0082] This embodiment provides a solid electrolyte (Li2CO3)1 / 3(Li3PO4)1 / 3(Li2SO4)1 / 3-HfCl4. Specifically, it follows the preparation method provided in Example 1, except that the raw materials and their amounts are replaced with a mixture of Li2CO3, Li3PO4, Li2SO4, and HfCl4 in a molar ratio of 1 / 3:1 / 3:1 / 3:1.

[0083] Comparative Example 1

[0084] This case study provides a solid electrolyte, and the specific preparation method is shown below:

[0085] In an anhydrous and oxygen-free argon atmosphere glove box, LiCl and ZrCl4 were mixed at a molar ratio of 2:1 and hand-ground for 10 minutes using an agate mortar to ensure thorough mixing.

[0086] The mixed powder (approximately 2 g) was transferred to a 75 mL ball mill jar, and 60 g of 3 mm diameter grinding beads were added accordingly. The ball mill jar was then evacuated and sealed. It was ball milled at 550 rpm for 20 h in a planetary ball mill, with the jar cooled by circulating water during the milling process. After milling was complete, the jar was transferred to a glove box, opened, and the powder inside was removed; this was the synthesized Li₂ZrCl₆ halide solid electrolyte.

[0087] Application Example 1

[0088] This embodiment provides an all-solid-state lithium battery, which is assembled using the solid electrolyte (Li2SO4) ZrCl4 provided in Example 6. The specific assembly process is as follows:

[0089] Step 1: Weigh out the commercially available lithium-ion layered oxide LiNi 0.88 Co 0.09 Mn 0.03 O2 (as the positive electrode active material), (Li2SO4)ZrCl4 (as the ion-conducting agent), and carbon black (as the conductive ion-conducting agent) in a mass ratio of 7:3:0.1 are manually ground in a mortar for 10 minutes until uniformly mixed to form a composite positive electrode.

[0090] Step 2: Weigh 50 mg of the solid electrolyte Li2SO4-ZrCl4 powder synthesized in Example 6, and cold-press it into a solid electrolyte sheet with a diameter of 10 mm. The pressure is 100 MPa, and the pressure is maintained for 2 min. Weigh 50 mg of Li6PS5Cl as a barrier layer between the solid electrolyte Li2SO4-ZrCl4 and the LiIn negative electrode, and evenly spread it on one side of the Li2SO4-ZrCl4 solid electrolyte sheet. Cold-press it at 100 MPa for 2 min.

[0091] Step 3: Weigh 10 mg of the composite positive electrode prepared in Step 1, spread it evenly on the other side of the (Li2SO4)ZrCl4 solid electrolyte sheet prepared in Step 2, and cold press it at a pressure of 350 MPa for 2 min.

[0092] Step 4: Using a commercially available indium sheet (10 mm in diameter and 200 μm in thickness) as the negative electrode active material, attach it to the other side of the Li6PS5Cl barrier layer prepared in step 2 to form an “electrolyte sheet-barrier layer-negative electrode sheet”. Apply a pressure of 100 MPa to complete the assembly and obtain an all-solid-state lithium battery.

[0093] Steps 1 through 4 are all performed in an argon atmosphere glove box in an anhydrous and oxygen-free environment.

[0094] Application Example 2

[0095] Assemble all-solid-state LiIn-LiNi using the method provided in Application Example 1. 0.88 Co 0.09 Mn 0.03 The O2 (LiIn-NMC88) battery differs in that the solid electrolyte used is the Li3PO4-TaCl5 solid electrolyte synthesized in Example 21.

[0096] Application Example 3

[0097] The all-solid-state LiIn-LiCoO2 battery is assembled using the method provided in Application Example 1, with the difference being that the positive electrode active material is LiNi. 0.88 Co 0.09 Mn 0.03 O2 was replaced with LiCoO2. The solid electrolyte used was the (Li3PO4)ZrCl4 solid electrolyte synthesized in Example 7.

[0098] The substances obtained in the examples and their corresponding properties are analyzed below.

[0099] I. Characterization Analysis

[0100] 1. Characterization and analysis of ionic conductivity

[0101] (1) Characterization method: In an anhydrous and oxygen-free argon atmosphere glove box, the solid electrolytes prepared in Examples 1-37 and Comparative Example 1 were filled into a cylindrical pressing mold (10 mm in diameter); and cold-pressed at 375 MPa for 2 min to obtain solid electrolyte sheets with a thickness of 0.5-1.5 mm and a diameter of 10 mm; after gold plating on the upper and lower surfaces of the solid electrolyte sheet, the upper and lower surfaces were clamped with two stainless steel blocking electrodes and connected to an electrochemical workstation, and the electrochemical impedance spectroscopy was tested at room temperature; the room temperature ionic conductivity was extracted from the measured electrochemical impedance spectrum, and the corresponding ionic conductivity was obtained from the electrochemical impedance spectrum characterized in Figure 2, as shown in Table 2.

[0102] (2) Characterization results: The ionic conductivity of the carrier salt CaAb is less than 10. -7 S cm -1 The solid electrolytes prepared by mixing with van der Waals crystal MBy all have ionic conductivity greater than 10. -3 S cm -1 Table 2 shows the ionic conductivity of the solid electrolytes synthesized in Examples 1-37, Comparative Example 1, and the control sample.

[0103] Table 2 Ionic conductivity of solid electrolytes

[0104]

[0105] 2. Local Structure Analysis

[0106] (1) Characterization methods: Fourier transform infrared spectroscopy, X-ray absorption spectroscopy and distribution function were used to characterize the solid electrolyte synthesized in the examples.

[0107] (2) Characterization results: As shown in Figure 3(b), 582 cm -1 and 1010 cm -1 Corresponding to the bending vibration of PO and PO4 respectively 3- Asymmetric stretching of anions. These peaks still exist in the (Li3PO4)ZrCl4 solid electrolyte, proving the presence of PO4. 3- The existence of these peaks and their shift to higher wavenumbers proves the existence of PO4. 3- Coordination with Zr. 700 cm -1 ~800 cm -1The formation of the new peak also proves the formation of the Zr-OP structure. Figure 4(c) shows the log distribution function of (Li3PO4)ZrCl4 solid electrolyte, and Figure 3(b) shows the X-ray absorption spectrum of (Li3PO4)ZrCl4 solid electrolyte. After local structure analysis, the local structure can be determined as follows: the Cl part in the ZrCl6 octahedron is replaced by O, and multiple ZrCl6 polyhedra are connected by multiple O in the PO4 tetrahedron. This local structure constitutes an open framework structure with a cross-linked network skeleton and penetrating three-dimensional channels. Li ions fill the vacancies in it. Figure 4(d) shows the log distribution function of (Li2CO3)ZrCl4 solid electrolyte, and Figure 3(c) shows the X-ray absorption spectrum of (Li2CO3)ZrCl4 solid electrolyte. After local structure analysis, the local structure can be determined as follows: the Cl part in the ZrCl6 octahedron is replaced by O, and multiple ZrCl6 polyhedra are connected by multiple O in the CO3 planar triangle. This local structure constitutes an open framework structure with a cross-linked network skeleton and penetrating three-dimensional channels. Li ions fill the vacancies in it. Figure 4(b) shows the pair distribution function of the Li2SO4-ZrCl4 solid electrolyte, and Figure 3(a) shows the X-ray absorption spectrum of the Li2SO4-ZrCl4 solid electrolyte. Through local structure analysis, the local structure can be determined as follows: the Cl portion of the [ZrCl6] octahedron is replaced by O, and multiple ZrCl6 polyhedra are connected by multiple O atoms in the SO4 tetrahedra. This local structure constitutes an open framework structure with a cross-linked network skeleton and penetrating three-dimensional channels, with Li ions filling the vacancies. Figure 4(a) shows the pair distribution function of the Li2O-ZrCl4 solid electrolyte. Through local structure analysis, the local structure can be determined as follows: the Cl portion of the [ZrCl6] octahedron is replaced by O, and multiple [ZrCl6] polyhedra are connected by O atoms, as shown in Figure 1.

[0108] 3. Crystal structure characterization and analysis

[0109] (1) Characterization method: The solid electrolyte prepared in the example was characterized by X-ray diffraction.

[0110] (2) Characterization results: As shown in Figure 5, the X-ray diffraction spectra of the solid electrolytes Li2CO3-HfCl4, Li2SO4-HfCl4, Li2CO3-ZrCl4, Li2SO4-ZrCl4, Li2O-TaCl5, 2 / 3Li3PO4-ZrCl4, and Li2C2O4-TaCl5 lithium salt-van der Waals crystal solid electrolytes are shown. The results show that none of these seven solid electrolytes exhibit obvious diffraction peaks, indicating that the above seven solid electrolytes are disordered amorphous phases.

[0111] Figure 6 shows the evolution of the crystal structure of the Li₂O-ZrCl₄ solid electrolyte with ball milling time. Throughout the ball milling process, the diffraction peaks are broad and of low intensity, indicating that the Li₂O-ZrCl₄ electrolyte is a material that is mostly amorphous with a small portion of nanocrystalline components. The nanocrystalline transformation is as follows: the raw material Li₂O phase gradually disappears, then the Li₂ZrCl₆ crystalline phase appears, and finally it becomes LiCl. The Li₂ZrCl₆ halide solid electrolyte provided in Comparative Example 1 has obvious diffraction peaks, which can be identified as Li₂ZrCl₆ (space group P-3m₁), indicating that this halide solid electrolyte is the crystalline phase Li₂ZrCl₆.

[0112] Figure 12 characterizes the four solid electrolytes, Li2O-AlCl3, Li2CO3-HfCl4, LiZrCl5, and Li2S-ZrCl4, prepared in Examples 33, 30, 34, and 2. 7 Li solid-state NMR spectroscopy. The results showed that all four provided solid electrolytes exhibited a peak around 0.5 ppm, corresponding to the amorphous phase within the solid electrolyte. Other peaks besides this one can be attributed to residual raw materials or precipitated LiCl. When C is Li, the solid electrolyte exhibits an amorphous or near-amorphous structure. + The coordination number ranges from 3 to 5; the Li + The coordination number range of 3 to 5 refers to the range of coordination numbers in solid-state NMR. 7 In the Li spectrum, the solid electrolyte exhibits characteristic peaks in the range of 0.4 ppm to 0.6 ppm;

[0113] Figure 13 characterizes the solid electrolyte of 2 / 3 Li3PO4-TaCl5 in Example 22, using a 1 mol / L NaCl aqueous solution at 0 ppm as a reference. 23 Na solid-state NMR spectroscopy. The results show that the sodium environment of this material consists of three... 23 The combined chemical shifts of Na are located around 7.2 ppm, -10.4 ppm, and -11.5 ppm. Ionic conductivity increases with increasing -11 ppm signal. + The peak shifted from -10.44 ppm to a higher field of -11.5 ppm. This indicates that the -11 ppm sodium environment dominated the Na content. + Conductivity. This indicates that when C is Na, the solid electrolyte is amorphous or nearly amorphous in structure, and Na... + The coordination number ranges from 7 to 9; the Na + The coordination number range of 7 to 9 refers to the range of coordination numbers in solid-state NMR. 23 In the Na spectrum, the solid electrolyte exhibits a characteristic peak around -11 ppm.

[0114] 4. Microstructural characterization and analysis

[0115] (1) Characterization method: The microstructure of the synthesized Li2O-ZrCl4 solid electrolyte was characterized by high-resolution cryo-transmission electron microscopy.

[0116] (2) Characterization results: The characterization results are shown in Figure 7. The results show that most of the Li2O-ZrCl4 solid electrolyte is a disordered amorphous phase, and the crystalline phase is LiCl with a grain size of about 10 nm. The crystalline phase is enriched on the surface of the particles.

[0117] Crystal structure characterization and microstructure characterization analyses show that lithium salts with different anions undergo solid-state reactions with van der Waals crystals to obtain materials with similar crystal and microstructures and high ionic conductivity. This solid-state reaction behavior is similar to the dissociation behavior of salts in solution and can be understood as the dissociation behavior of lithium salts (solutes) in van der Waals crystals (solid solvents).

[0118] II. Electrochemical Performance Testing

[0119] 1. Electrochemical window testing

[0120] (1) Test method: At room temperature, the battery configured as solid electrolyte + carbon black (mass ratio 5:5) solid electrolyte|Li6PS5Cl|Li was tested by linear scan method using EC-lab electrochemical workstation.

[0121] The solid electrolytes were Li2O-ZrCl4, Li3PO4-ZrCl4 synthesized in Comparative Example 1, and Li2ZrCl6 synthesized in Comparative Example 1, respectively.

[0122] (2) Test results: As shown in Figure 8, the oxidation limit of Li3PO4-ZrCl4 is 4.3 V, which is greater than the oxidation limit of Li2ZrCl6 (3.75 V) and Li2O-ZrCl4 (3.85 V) in Comparative Example 1.

[0123] 2. Constant current charge-discharge test

[0124] (1) Test method: At room temperature, constant current charge and discharge test was performed using the all-solid-state battery provided in Case 1 of the Blue Battery Test System, with a voltage range of 2.5 V to 4.3 V (relative to Li). + (Voltage of Li), the first 3 cycles use a 0.1 C rate for activation, and from the 4th cycle onwards use a 2 C rate.

[0125] (2) Test Results: The test results are shown in Figure 9. Using the all-solid-state battery provided in Example 1, at a 2C rate, the reversible capacity of the all-solid-state lithium battery after 100 cycles is 127 mAh g. -1 The capacity decays almost without any reduction.

[0126] 3. Fast charging performance test

[0127] (1) Test method: At room temperature, the all-solid-state battery provided in Case 2 of the Blue Battery Test System was used for cycle performance testing, with a voltage range of 2.5 V to 4.3 V (relative to Li). + / Li voltage), with a cycle rate of 5 C.

[0128] (2) Test results: The specific capacity-cycle number graph for the first 100 cycles is shown in Figure 10. The results show that the reversible capacity of the first cycle (5 C rate) is approximately 81.6 mAh g. -1 After 100 cycles, there was no capacity decay. The battery performance results in Figure 15 show that the all-solid-state lithium battery assembled using the (Li3PO4)TaCl5 solid electrolyte exhibits excellent high capacity and cycle stability at room temperature.

[0129] 4. Low-temperature service performance testing

[0130] (1) Test method: At low temperature (-30 ℃), constant current charge and discharge test was performed using the all-solid-state battery provided in Case 3 of the Blue Battery Test System, with a voltage range of 2.5 V~4.6 V (relative to Li). + / Li voltage), with a cycle rate of 0.1 C.

[0131] (2) Test results: The results are shown in Figure 11. The results show that the assembled all-solid-state battery still has a capacity of 153 mAh g at low temperature (-30 ℃). -1 The specific capacity shows that the capacity retention rate is 83.6% after 150 stable cycles, indicating its excellent low-temperature performance.

Claims

1. A solid electrolyte, characterized in that, The general formula is (C a N b ) x- MB y ; Among them, MB y Using van der Waals crystals as the structural framework, y represents the number of atoms of element B; C a N b Let a and b be the number of cation donor C and anion donor N atoms in the carrier salt, respectively; x is the number of C atoms. a N b and MB y stoichiometry; The anion donor N partially replaces MB. y The B site forms a framework structure with a channel for the migration of charge carrier ions; the dissociated cation donor C fills the voids in the framework structure.

2. The solid electrolyte according to claim 1, characterized in that, The van der Waals crystal is one or more of halide van der Waals crystals, sulfide van der Waals crystals and oxide van der Waals crystals; The MB y M is one or more of Zr, Hf, Ta, Nb, Al, Fe, Ga, In, Mo, W, Y, Ti, Si, B, and Sb; B is one or more of F, Cl, Br, I, S, or O.

3. A solid electrolyte according to claim 1, characterized in that, The anion donor N includes polyanion XO. m n- Polyanionic derivative group X m O 3m+1 n- Or simple anions; The simple anion is a halogen or OH-. - NH2 - O2 2- O 2- S 2- or N 3- One or more of the following; The polyanion XO m n- Or the derivatized group X of the polyanion m O 3m+1 n- In this context, X is one or more of B, S, P, Si, As, Mo, W, or C; m is 2-4; and n is the charge number.

4. A solid electrolyte according to claim 3, characterized in that, The anion donor N is a polyanion XO m n- Or the derivatized group X of the polyanion m O 3m+1 n- The MB y B element XO m n- or X m O 3m+1 n- replace.

5. A solid electrolyte according to claim 1, characterized in that, The cation donor C is Li + Na + Ag + Cu + or K + Among them, Li + The coordination number ranges from 3 to 5, Na + The coordination number ranges from 7 to 9.

6. A solid electrolyte according to claim 1, characterized in that, The dissociated cation donor C is partially transported within the framework structure as a charge carrier, and the other part interacts with MB. y Alternatively, B may form nanocrystals; wherein the content of nanocrystals in the solid electrolyte is <30 wt%; The nanocrystals include C e MB f and CB, where C e MB f In this context, e and f are the stoichiometric coefficients of the cation donors C and MB, respectively. In the framework structure, (C a N b ) x- MB y It is granular, C e MB f Alternatively, CB may adhere to the surface of the particles, which are amorphous phases, while nanocrystals are crystalline phases.

7. A solid electrolyte according to claim 1, characterized in that, The solid electrolyte (C) a N b ) x- MB y It has an amorphous or nearly amorphous structure, with x ranging from 0.2 to 2 and y ranging from 3 to 6.

8. The method for preparing a solid electrolyte as described in claim 1, characterized in that, Includes the following steps: Under an anhydrous and oxygen-free inert atmosphere, C is added according to stoichiometric ratio. a N b and MB y Solid-phase reaction occurs through mechanical ball milling to obtain a solid electrolyte (C). a N b ) x- MB y .

9. The method for preparing a solid electrolyte according to claim 8, characterized in that, The control parameters for the mechanical ball milling method include: The grinding beads have a diameter of 3 mm to 10 mm; The total mass ratio of grinding beads to raw materials is 60:1 to 20:1; The ball milling time is 1 h to 30 h; The ball mill speed is 400 r / min to 800 r / min.

10. A battery, characterized in that, It includes the solid electrolyte as described in claim 1.

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