Alkali metal-rich nasicon-type solid-state electrolyte, and preparation method therefor and use thereof

Abstract

An alkali metal-rich NASICON-type solid-state electrolyte, and a preparation method therefor and a use thereof. The chemical general formula of the novel alkali metal-rich NASICON-type solid-state electrolyte is A1+x+yMxN2-x(BO4)3, wherein 0≤x≤3 and 0≤y≤26; A is any one of elements Li, Na, K, Mg, and Ca; B is one or more of elements B, P, Si, S, Se, As, and Te; M is one or more of elements Al, Ga, Cd, Mn, Co, Ni, Zn, Fe, Sc, Cr, In, Y, and Ln; and N is one or more of elements Ti, Sn, Ge, Zr, Hf, V, Nb, Ta, and Sb. The alkali metal-rich NASICON-type solid-state electrolyte is obtained by adding an alkali metal activator having a particle size D50 of 1 nm-10 μm to react with other raw materials in the preparation process.

Description

A novel alkali metal-rich NASICON-type solid electrolyte and its preparation method and application

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on September 22, 2023, with application number 202311225852.6 and invention name “A new type of alkali metal-rich NASICON-type solid electrolyte, its preparation method and application”. Technical Field

[0002] The present invention relates to the technical field of secondary battery materials, and in particular to a novel alkali metal-rich NASICON-type solid electrolyte and a preparation method and application thereof. Background Art

[0003] In recent years, the application market has put forward higher and higher requirements for the safety and energy density of lithium-ion batteries. For this reason, researchers have increasingly turned their attention to the field of solid-state batteries, hoping to achieve a comprehensive improvement in battery safety and energy density. Solid electrolytes can generally be divided into two categories: inorganic solid electrolytes and polymer solid electrolytes. Sodium fast ion conductor (NASCICON) type solid electrolyte A 1+x M x N 2-x (BO4)3, such as lithium aluminum titanium phosphate Li 1+x Al x Ti 2-x (PO4)3(LATP) is a type of inorganic solid electrolyte that has attracted much attention in recent years. NASICON-type solid electrolytes exhibit high ionic conductivity at room temperature, and have low requirements for storage and assembly conditions. Their structural properties are very stable in air and humid environments. Since NASICON-type solid electrolytes have a very high ion transfer rate, they can be used not only as solid electrolytes, but also as positive electrode coating materials. They can not only avoid direct contact between the electrolyte and the positive electrode material, thereby improving cycle stability, but also increase the diffusion rate of lithium ions on the surface of the material, thereby further improving rate and low-temperature performance. However, the application of NASICON-type solid electrolytes in high-voltage positive electrodes and lithium metal and its composite electrodes still has serious interface problems, which restricts its further development.

[0004] NASICON solid electrolytes have high hardness and are difficult to fully contact with positive and negative electrode active materials when in direct contact, resulting in high interface impedance of solid-state batteries. Their discontinuous ion / electron transmission channels are also prone to the formation of lithium dendrites. In addition, NASICON solid electrolytes will undergo redox reactions when in contact with metal lithium negative electrodes and high-voltage positive electrodes. For example, metal Li will convert Ti in the electrolyte into 4+ Reduction to Ti 3+, causing the electrolyte structure to collapse and even inactivate. These problems hinder the practical application of NASICON-type solid electrolytes.

[0005] Therefore, it is necessary to modify the NASICON solid electrolyte to enhance the interfacial contact, reduce the interfacial impedance, inhibit the occurrence of interfacial side reactions, improve the interfacial compatibility between electrodes, and obtain a secondary battery with stable interface and excellent performance.

[0006] Summary of the Invention

[0007] The embodiments of the present invention provide a novel alkali metal-rich NASICON-type solid electrolyte, its preparation method, and application. By adding an alkali metal activator during the sintering process, the carrier transport efficiency is improved and the electrochemical reaction barrier is reduced. The application of this novel alkali metal-rich NASICON-type solid electrolyte in secondary batteries can significantly reduce interfacial impedance, reduce the occurrence of side reactions at the active material interface, improve ionic conductivity and chemical stability, and at the same time solve the problem of unsafe commercial batteries.

[0008] To this end, in the first aspect, the embodiment of the present invention provides a novel alkali metal-rich NASICON type solid electrolyte, the chemical formula of the alkali metal-rich NASICON type solid electrolyte is A 1+x+y M x N 2-x (BO4)3, wherein 0≤x≤3, 0≤y≤26; A is any one of Li, Na, K, Mg, and Ca; B is one or more of B, P, Si, S, Se, As, and Te; M is one or more of Al, Ga, Cd, Mn, Co, Ni, Zn, Fe, Sc, Cr, In, Y, and Ln; and N is one or more of Ti, Sn, Ge, Zr, Hf, V, Nb, Ta, and Sb.

[0009] The novel alkali metal-rich NASICON solid electrolyte is prepared by adding a particle size D 50 It is obtained by reacting 1nm-10μm alkali metal activators with other raw materials;

[0010] The alkali metal activator includes any one of a lithium activator, a sodium activator or a potassium activator;

[0011] The lithium activator includes one or more of LiH, Li2S, Li2SO4, C2H5LiO, CH3LiO, Li2C2O4, a mixture of lithium-aromatic hydrocarbon-ether solvents, LiClO4, LiSO, LiAlSO, and LiBF4; the mixture of lithium-aromatic hydrocarbon-ether solvents includes one or more of lithium-biphenyl-ethylene glycol dimethyl ether mixture, lithium-biphenyl-tetrahydrofuran mixture, lithium-naphthalene-tetrahydrofuran mixture, and lithium-naphthalene-dioxolane mixture;

[0012] The sodium activator includes one or more of NaH, Na2O, Na2O2, Na2S, NaOH, Na2CO3, CH3COONa, Na2SO4, NaCl, NaF, Na3PO4, C2H5NaO, CH3NaO, Na2C2O4, a mixture of sodium-aromatic hydrocarbon-ether solvent, NaAlSO, NaTFSI, and NaFSI; the sodium-aromatic hydrocarbon-ether solvent mixture includes one or more of a sodium-naphthalene-tetrahydrofuran mixture, a sodium-naphthalene-dioxolane mixture, a sodium-naphthalene-tetrahydrofuran mixture, and a sodium-biphenyl-tetrahydrofuran mixture;

[0013] The potassium activator includes one or more of KH, K2O, K2O2, K2S, KOH, K2CO3, KF, K3PO4, C2H5KO, CH3KO, K2C2O4, a mixture of potassium-aromatic hydrocarbon-ether solvent, KPF6, KClO4, KSO, KAlSO, KBF4, KTFSI, and KFSI; the mixture of potassium-aromatic hydrocarbon-ether solvent includes one or more of potassium-naphthalene-tetrahydrofuran mixture, potassium-naphthalene-dioxolane mixture, potassium-biphenyl-ethylene glycol dimethyl ether mixture, and potassium-biphenyl-tetrahydrofuran mixture;

[0014] The novel alkali metal-rich NASICON solid electrolyte was subjected to X-ray testing using a Cu-Kα target, and had diffraction peaks at 2θ=20.8±0.5°, 22.2±0.5°, 23±0.5°, and 24.5±0.5°; the diffraction peak had two weak diffraction peaks between 21.7° and 23.5°, three characteristic peaks between 32° and 37°, at 2θ=33.3±0.5°, 33.8±0.5°, and 36.5±0.5°, and a weak impurity peak near 34°;

[0015] The diffraction peak intensities at the positions of 2θ=20.8±0.5°, 22.2±0.5°, 23±0.5°, 24.5±0.5°, 33.3±0.5°, 33.8±0.5°, and 36.5±0.5° are sequentially designated as I1, I2, I3, I4, I5, I6, and I7, wherein the peak intensity ratio of I1:I4 is 0.1:1-1:1, the peak intensity ratio of I2:I3 is 0.1:1-2:1, the peak intensity ratio between I5:I6 is 1:2-2:1, and the peak intensity ratio between I5:I7 is 1:2-2:1;

[0016] The main crystal structure of the novel alkali metal-rich NASICON-type solid electrolyte belongs to the Pmnb space group and the P-43n space group, among which the Pmnb space group is dominant.

[0017] Preferably, when x=0.3 or x=0.5, 0.5≤y≤26.

[0018] Preferably, the novel alkali metal-rich NASICON-type solid electrolyte has an appearance of off-white powder, and a lightness L in the Lab color model ranges from 0≤L<15.

[0019] In a second aspect, an embodiment of the present invention provides a method for preparing the novel alkali metal-rich NASICON-type solid electrolyte described in the first aspect, the preparation method comprising:

[0020] The raw materials are weighed according to the stoichiometric ratio of the NASICON solid electrolyte: A source material, B source material, M source material, N source material, and an alkali metal activator.

[0021] Under protective atmosphere, the raw materials and particle size D 50 Alkali metal activators with particle sizes of 1 nm to 10 μm are added into a mixing device in descending order of particle size and mixed evenly to obtain a mixed material.

[0022] The mixed material is evenly dispersed and spread in a crucible, and placed in a high-temperature furnace under a protective atmosphere for the first high-temperature sintering treatment. After the temperature is cooled to room temperature for the first time, the intermediate material is obtained.

[0023] Under a protective atmosphere, the intermediate material is placed in a pulverizer for crushing and dispersion, and the precursor material is obtained after uniform mixing.

[0024] The precursor material is evenly dispersed and spread in a crucible, and placed in a high-temperature furnace under a protective atmosphere for a second sintering treatment. After cooling to room temperature for the second time, the material is crushed and sieved to obtain a new alkali metal-rich NASICON-type solid electrolyte.

[0025] The source material A includes one or more of Li2O, Li2O2, LiOH, Li2CO3, CH3COOLi, LiNO3, LiPF6, LiAsF6, LiBF4, LiFSI, LiTFSI, LiCF3SO3, LiCF3SO3·LiOAc, LiC2H3O2, LiCl, LiF, Li3PO4, lithium bis(oxalatoborate) LiBOB, lithium difluorooxalatoborate LiDFOB, Li2B4O7, NaPF6, NaClO4, NaAlClh, NaFeClh, NaSO, NaBF4, NaNO3, NaPOFA, KCl, KNO3, KH2PO4, K2SO4, and CH3COOK;

[0026] The B source material includes one or more of: H2PO4, NH2H2PO4, (NH2)2HPO4, SiO2, SiH4, CH3SiH3, CS2, P2S3, SeO2, and CdSe;

[0027] The M source materials include: Al2O3, Al(OH)3, AlOOH, Al2(CO3)3, C9H 21 One or more of AlO3, Al(NO3)3·9H2O, Al[OOCH3(OH)2]·xH2O, GaCl3, GaBr3, GaI3, Ga(NO3)3, Ga2(SO4)3;

[0028] The N source materials include: TiCl4, Ti(NO3)4, isobutyl titanate IPT, dibutyl titanate DBTDP, tetrabutyl titanate TBT, C 16 H 36 One or more of O4Ti, Ti(n-C3H7O)4, Ti(OC4H9)4, ZrO2, ZrSiO4, ZrSO4, ZrOCl2, ZrC, ZrCO3, ZrB, and ZrB2;

[0029] The alkali metal activator includes any one of a lithium activator, a sodium activator or a potassium activator; wherein the lithium activator includes one or more of LiH, Li2S, Li2SO4, C2H5LiO, CH3LiO, Li2C2O4, a mixture of lithium-aromatic hydrocarbon-ether solvents, LiCIO4, LiSO, LiAlSO, and LiBF4; the mixture of lithium-aromatic hydrocarbon-ether solvents includes one or more of a lithium-biphenyl-ethylene glycol dimethyl ether mixture, a lithium-biphenyl-tetrahydrofuran mixture, a lithium-naphthalene-tetrahydrofuran mixture, and a lithium-naphthalene-dioxolane mixture;

[0030] The sodium activator includes one or more of NaH, Na2O, Na2O2, Na2S, NaOH, Na2CO3, CH3COONa, Na2SO4, NaCl, NaF, Na3PO4, C2H5NaO, CH3NaO, Na2C2O4, a mixture of sodium-aromatic hydrocarbon-ether solvent, NaAlSO, NaTFSI, and NaFSI; the sodium-aromatic hydrocarbon-ether solvent mixture includes one or more of a sodium-naphthalene-tetrahydrofuran mixture, a sodium-naphthalene-dioxolane mixture, a sodium-naphthalene-tetrahydrofuran mixture, and a sodium-biphenyl-tetrahydrofuran mixture;

[0031] The potassium activator includes: KH, K2O, K2O2, K2S, KOH, K2CO3, KF, K3PO4, C2H5KO, CH3KO, K2C2O4, a mixture of potassium-aromatic hydrocarbon-ether solvents, KPF6, KClO4, KSO, KAlSO, KBF4, KNO 3、 One or more of KTFSI and KFSI; the potassium-aromatic hydrocarbon-ether solvent mixture includes one or more of potassium-naphthalene-tetrahydrofuran mixture, potassium-naphthalene-dioxolane mixture, potassium-biphenyl-ethylene glycol dimethyl ether mixture, and potassium-biphenyl-tetrahydrofuran mixture;

[0032] The conditions for the first high-temperature sintering treatment are specifically as follows: heating to 500°C-850°C at a heating rate of 1°C / min-3°C / min, and keeping warm for 4-7 hours; the conditions for the second sintering treatment are specifically as follows: heating to 300°C-650°C at a heating rate of 1°C / min-3°C / min, and keeping warm for 2-6 hours.

[0033] Preferably, the particle size D50 of the alkali metal activator is between 1 nm and 10 μm; and the molar ratio of the NASICON solid electrolyte to the alkali metal activator is [1:0.5]-[1:6.5].

[0034] Preferably, the protective atmosphere includes one or more of nitrogen, argon, hydrogen, helium or neon.

[0035] The mixing equipment is a high-speed disperser with a stirring speed between 1500rpm and 5000rpm. The specific method for uniform mixing is: stirring for 20min to 60min after each addition, and stirring for 1 hour to 3 hours after the last addition.

[0036] The cooling rates of the first cooling to room temperature and the second cooling to room temperature are both 1° C. / min-5° C. / min.

[0037] In a third aspect, an embodiment of the present invention provides an application of the novel alkali metal-rich NASICON-type solid electrolyte described in the first aspect above, wherein the novel alkali metal-rich NASICON-type solid electrolyte is used in one or more of electrolytes, diaphragms, positive electrode material additives, negative electrode material additives, and electrolyte additives.

[0038] In a fourth aspect, an embodiment of the present invention provides a secondary battery, which includes one or more of the electrolyte, separator, positive electrode material additive, negative electrode material additive, and electrolyte additive described in the third aspect.

[0039] Preferably, the secondary battery includes any one of a lithium ion battery, a sodium ion battery, and a potassium ion battery.

[0040] The embodiment of the present invention provides a novel alkali metal-rich NASICON-type solid electrolyte and its preparation method and application. Unlike traditional microscopic heterovalent element doping, this solution is to introduce lithium salt / sodium salt / potassium salt for bulk activation, destroy the original local crystal structure, and introduce a new macro-scale lattice structure into the traditional NASICON-type solid electrolyte structure under chemical potential drive by the activator. The characteristics of this new lattice structure make the novel alkali metal-rich NASICON-type solid electrolyte have high ion / electron transport performance and excellent interface stability. The introduction of the activator from the raw material end of the NASICON-type solid electrolyte can be highly compatible with the traditional typical high-temperature solid-phase synthesis process route, greatly reducing the manufacturing cost of the new material. Because it has ultra-high room temperature ion transport function and interface stability, it can be used as one or more of electrolytes, separators, positive electrode material additives, negative electrode material additives or electrolyte additives in secondary batteries, which can significantly reduce the interface impedance of the secondary battery, improve the carrier transport efficiency, and improve the cycle stability of the secondary battery.

[0041] The embodiment of the present invention provides a method for preparing a novel alkali metal-rich NASICON-type solid electrolyte, which is simple to operate, highly integrated with existing alkali metal-rich NASICON-type solid electrolyte preparation processes, has low production costs, and is easy to achieve large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The technical solutions of the embodiments of the present invention are further described in detail below through the accompanying drawings and examples.

[0043] FIG1 is a flow chart of a method for preparing a novel alkali metal-rich NASICON-type solid electrolyte provided in an embodiment of the present invention.

[0044] FIG2 is a physical picture of the novel alkali metal-rich NASICON-type solid electrolyte prepared in Example 1 of the present invention.

[0045] FIG3 is a comparison chart of X-ray diffraction (XRD) of the novel alkali metal-rich NASICON solid electrolyte prepared in Example 1 of the present invention and the conventional NASICON solid electrolyte prepared in Comparative Example 1.

[0046] FIG4 is a schematic diagram of the space group structure of the novel alkali metal-rich NASICON-type solid electrolyte prepared in Example 1 of the present invention.

[0047] FIG5 is a comparison diagram of the electrochemical impedance spectra (EIS) of lithium-ion all-solid-state batteries assembled with the novel alkali metal-rich NASICON-type solid electrolyte prepared in Example 1 of the present invention and the traditional NASICON-type solid electrolyte in Comparative Example 1.

[0048] FIG6 is a cycle capacity curve of a lithium-ion all-solid-state battery assembled with a novel alkali metal-rich NASICON-type solid electrolyte provided in Example 1 of the present invention.

[0049] FIG7 is an XRD pattern of the novel alkali metal-rich NASICON-type solid electrolyte prepared in Example 2 of the present invention.

[0050] FIG8 is an XRD pattern of the novel alkali metal-rich NASICON-type solid electrolyte prepared in Example 3 of the present invention.

[0051] FIG9 is an XRD pattern of the novel alkali metal-rich NASICON-type solid electrolyte prepared in Example 4 of the present invention.

[0052] FIG10 is an XRD pattern of the novel alkali metal-rich NASICON-type solid electrolyte prepared in Example 5 of the present invention.

[0053] FIG11 is an XRD pattern of the novel alkali metal-rich NASICON-type solid electrolyte prepared in Example 6 of the present invention. DETAILED DESCRIPTION

[0054] The present invention will be further described in detail below through the accompanying drawings and specific examples, but it should be understood that these examples are only used for more detailed explanation and should not be understood as limiting the present invention in any form, that is, they are not intended to limit the scope of protection of the present invention.

[0055] The embodiment of the present invention provides a novel alkali metal-rich NASICON type solid electrolyte, which is prepared by adding a particle size D 50The novel alkali metal-rich NASICON-type solid electrolyte is obtained by reacting an alkali metal activator with a diameter of 1nm-10μm with other raw materials; the alkali metal activator includes any one of a lithium activator, a sodium activator or a potassium activator; the main crystal structure of the novel alkali metal-rich NASICON-type solid electrolyte belongs to the Pmnb space group and the P-43n space group, among which the Pmnb space group is predominant; the appearance of the novel alkali metal-rich NASICON-type solid electrolyte is an off-white powder, and the lightness L in the Lab color model ranges from 0≤L<15.

[0056] The chemical formula of the new alkali metal-rich NASICON solid electrolyte is A 1+x+y M x N 2-x (BO4)3, wherein 0≤x≤3, 0≤y≤26, preferably, when x=0.3 or x=0.5, 0.5≤y≤26; A is any one of Li, Na, K, Mg, and Ca; B is one or more of B, P, Si, S, Se, As, and Te; M is one or more of Al, Ga, Cd, Mn, Co, Ni, Zn, Fe, Sc, Cr, In, Y, and Ln; and N is one or more of Ti, Sn, Ge, Zr, Hf, V, Nb, Ta, and Sb.

[0057] The novel alkali metal-rich NASICON solid electrolyte provided in an embodiment of the present invention was subjected to X-ray testing using a Cu-Kα target, and had diffraction peaks at 2θ=20.8±0.5°, 22.2±0.5°, 23±0.5°, and 24.5±0.5°.

[0058] There are two weak diffraction peaks between 21.7° and 23.5°, three characteristic peaks of 2θ=33.3±0.5°, 33.8±0.5° and 36.5±0.5° between 32° and 37°, and a weak miscellaneous peak near 34°.

[0059] Among them, the diffraction peak intensities appearing at the diffraction angles 2θ = 20.8±0.5°, 22.2±0.5°, 23±0.5°, 24.5±0.5°, 33.3±0.5°, 33.8±0.5°, and 36.5±0.5° are respectively set as I1, I2, I3, I4, I5, I6, and I7, among which the peak intensity ratio of I1:I4 is 0.1:1-1:1, the peak intensity ratio of I2:I3 is 0.1:1-2:1, the peak intensity ratio between I5:I6 is 1:2-2:1, and the peak intensity ratio between I5:I7 is 1:2-2:1.

[0060] An embodiment of the present invention provides a method for preparing the novel alkali metal-rich NASICON-type solid electrolyte, as shown in FIG1 , which specifically includes the following steps.

[0061] Step 110 , weighing raw materials according to the stoichiometric ratio of the NASICON solid electrolyte: A source material, B source material, M source material, N source material, and weighing an alkali metal activator.

[0062] Among them, source material A includes but is not limited to one or more of: Li2O, Li2O2, LiOH, Li2CO3, CH3COOLi, LiNO3, LiPF6, LiAsF6, LiBF4, LiFSI, LiTFSI, LiCF3SO3, LiCF3SO3·LiOAc, LiC2H3O2, LiCl, LiF, Li3PO4, lithium bis(oxalatoborate) LiBOB, lithium difluorooxalatoborate LiDFOB, Li2B4O7, NaPF6, NaClO4, NaAlClh, NaFeClh, NaSO, NaBF4, NaNO3, NaPOFA, KCl, KNO3, KH2PO4, K2SO4, and CH3COOK.

[0063] B source materials include but are not limited to: one or more of H2PO4, NH2H2PO4, (NH2)2HPO4, SiO2, SiH4, CH3SiH3, CS2, P2S3, SeO2, and CdSe.

[0064] M source materials include but are not limited to: Al2O3, Al(OH)3, AlOOH, Al2(CO3)3, C9H 21 One or more of AlO3, Al(NO3)3·9H2O, Al[OOCH3(OH)2]·xH2O, GaCl3, GaBr3, GaI3, Ga(NO3)3, and Ga2(SO4)3.

[0065] N source materials include but are not limited to: TiCl4, Ti(NO3)4, isobutyl titanate IPT, dibutyl titanate DBTDP, tetrabutyl titanate TBT, C 16 H 36 One or more of O4Ti, Ti(n-C3H7O)4, Ti(OC4H9)4, ZrO2, ZrSiO4, ZrSO4, ZrOCl2, ZrC, ZrCO3, ZrB, and ZrB2.

[0066] The alkali metal activator includes any one of a lithium activator, a sodium activator or a potassium activator; wherein the lithium activator includes but is not limited to one or more of LiH, Li2S, Li2SO4, C2H5LiO, CH3LiO, Li2C2O4, a mixture of lithium-aromatic hydrocarbon-ether solvents, LiCIO4, LiSO, LiAlSO, and LiBF4; wherein the mixture of lithium-aromatic hydrocarbon-ether solvents includes one or more of a lithium-biphenyl-ethylene glycol dimethyl ether mixture, a lithium-biphenyl-tetrahydrofuran mixture, a lithium-naphthalene-tetrahydrofuran mixture, and a lithium-naphthalene-dioxolane mixture.

[0067] Sodium activators include, but are not limited to, one or more of NaH, Na2O, Na2O2, Na2S, NaOH, Na2CO3, CH3COONa, Na2SO4, NaCl, NaF, Na3PO4, C2H5NaO, CH3NaO, Na2C2O4, a mixture of sodium-aromatic hydrocarbon-ether solvents, NaAlSO, NaTFSI, and NaFSI; the sodium-aromatic hydrocarbon-ether solvent mixture includes one or more of a sodium-naphthalene-tetrahydrofuran mixture, a sodium-naphthalene-dioxolane mixture, a sodium-naphthalene-tetrahydrofuran mixture, and a sodium-biphenyl-tetrahydrofuran mixture.

[0068] Potassium activators include but are not limited to: KH, K2O, K2O2, K2S, KOH, K2CO3, KF, K3PO4, C2H5KO, CH3KO, K2C2O4, potassium-aromatic hydrocarbon-ether solvent mixtures, KPF6, KClO4, KSO, KAlSO, KBF4, KNO 3、 One or more of KTFSI and KFSI; the mixture of potassium-aromatic hydrocarbon-ether solvents includes one or more of potassium-naphthalene-tetrahydrofuran mixture, potassium-naphthalene-dioxolane mixture, potassium-biphenyl-ethylene glycol dimethyl ether mixture, and potassium-biphenyl-tetrahydrofuran mixture.

[0069] Particle size D of alkali metal activator 50 Between 1nm-10μm.

[0070] The molar ratio of the NASICON solid electrolyte to the alkali metal activator is [1:0.5]-[1:6.5], and can be any molar ratio within this range, for example, 1:0.5, 1:0.6, 1:0.8, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:0.5, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6.5, etc., but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0071] Step 120: In a protective atmosphere, the raw materials and the particle size D 50 Alkali metal activators with particle sizes of 1 nm to 10 μm are added into a mixing device in descending order of particle size and mixed evenly to obtain a mixed material.

[0072] The mixing equipment is a high-speed disperser with a stirring speed between 1500rpm and 5000rpm. The specific method for uniform mixing is: stirring for 20min to 60min after each addition, and stirring for 1 hour to 3 hours after the last addition.

[0073] The present invention can obtain better reaction effect by adding raw materials and alkali metal activator in the order of particle size from large to small.

[0074] Step 130: Evenly disperse the mixed material in a crucible, place it in a high-temperature furnace under a protective atmosphere, perform a first high-temperature sintering treatment, and cool it to room temperature for the first time to obtain an intermediate material;

[0075] The conditions for the first high-temperature sintering treatment are as follows: heating to 500-850°C at a heating rate of 1-3°C / min and keeping at that temperature for 4-7 hours; cooling to room temperature at a cooling rate of 1-5°C / min.

[0076] Step 140: Under a protective atmosphere, the intermediate material is placed in a pulverizer for crushing and dispersion, and mixed to obtain a precursor material.

[0077] Among them, the crusher is a jaw crusher and / or a roller crusher.

[0078] The particle size D50 of the obtained precursor material is between 100 nm and 10 μm.

[0079] Step 150 , the precursor material is evenly dispersed and spread in a crucible, and placed in a high-temperature furnace under a protective atmosphere for a second sintering treatment. After cooling to room temperature for the second time, the material is crushed and sieved to obtain a novel alkali metal-rich NASICON-type solid electrolyte.

[0080] The conditions for the second high-temperature sintering treatment are as follows: heating to 300-650°C at a heating rate of 1-3°C / min and keeping at that temperature for 2-6 hours; cooling to room temperature for the second time at a cooling rate of 1-5°C / min.

[0081] In the above-mentioned preparation method provided by the embodiment of the present invention, the protective atmosphere mentioned is one or more atmospheres of nitrogen, argon, hydrogen, helium or neon.

[0082] In the present invention, the particle size D of the alkali metal activator is 50Between 1nm-10μm, it can be any specific value within the above range, such as 1nm, 10nm, 20nm, 50nm, 70nm, 100nm, 200nm, 500nm, 1μm, 2μm, 10μm, etc., but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0083] The present invention adds particle size D in the preparation process 50 A new type of alkali metal-rich NASICON solid electrolyte is obtained by reacting 1nm-10μm alkali metal activator with other raw materials. The mechanism is: the traditional NASICON solid electrolyte A 1+x M x N 2-x (BO4)3 is a hexagonal triclinic structure with unstable redox properties, which is determined by its crystalline structure. AO4 and MO6 form a three-dimensional skeleton with a common vertex at the vertex position. A atoms occupy the A1 and A2 positions, and ions conduct particles by jumping between the two sites. In order to improve the above problems, we introduce the particle size D 50 The alkali metal activator is 1nm-10μm. In the process of preparing the new alkali metal-rich NASICON solid electrolyte, the alkali metal ions in the alkali metal activator fill the vacancy defects around AO4, increase its local structural distortion, and increase the density of A atomic sites, which greatly improves the performance of ion transmission and electron transmission, and can effectively reduce the redox driving force brought by the chemical potential. At the same time, the contact resistance formed by the interface structure is further reduced.

[0084] The novel alkali metal-rich NASICON-type solid electrolyte prepared by the above-mentioned preparation method of the present invention can be used as one or more of an electrolyte, a separator, a positive electrode material additive, a negative electrode material additive or an electrolyte additive in a secondary battery; the secondary battery includes any one of a lithium ion battery, a sodium ion battery and a potassium ion battery; the secondary battery using the novel alkali metal-rich NASICON-type solid electrolyte of the present invention can significantly reduce the interfacial impedance of the secondary battery, improve the carrier transport efficiency, and improve the cycle stability of the secondary battery.

[0085] In order to better understand the technical solution provided by the present invention, the preparation process and characteristics of the novel alkali metal-rich NASICON-type solid electrolyte of the present invention are respectively described below with multiple specific examples.

[0086] Example 1

[0087] This embodiment provides a preparation process and performance test of a novel alkali metal-rich NASICON-type solid electrolyte. The specific preparation process is as follows.

[0088] (1) According to NASICON solid electrolyte Li 1.3 Al 0.3 Ti 1.7 Weigh the raw materials in the stoichiometric ratio of (PO4)3: A source material Li2SO4, B source material (NH2)2HPO4, M source material Al(OH)3, N source material C 16 H 36 O4Ti, and weigh the alkali metal activator LiOH.

[0089] Among them, the particle size D of Li2SO4 50 The particle size D of (NH2)2HPO4 is 50μm 50 The particle size D of Al(OH)3 is 20nm. 50 10μm, C 16 H 36 Particle size D of O4Ti 50 The particle size of LiOH is 100 nm. 50 10nm; NASICON solid electrolyte Li 1.3 Al 0.3 Ti 1.7 The molar ratio of (PO4)3 to LiOH is [1:6.5].

[0090] (2) Under a nitrogen atmosphere, the raw materials and alkali metal activator weighed in step (1) are added to a high-speed disperser in descending order of particle size, the stirring speed is set to 1500 rpm, and the mixture is stirred for 20 minutes after each addition, and stirred for another hour after the last addition to mix uniformly to obtain a mixed material.

[0091] (3) The mixed material was evenly dispersed and spread in a crucible, placed in a high-temperature furnace under a nitrogen atmosphere, and heated to 600°C at a heating rate of 3°C / min, kept at this temperature for 5 hours, and subjected to the first high-temperature sintering treatment. The intermediate material was obtained after cooling to room temperature at a cooling rate of 3°C / min.

[0092] (4) Under a nitrogen atmosphere, the intermediate material was placed in a roller crusher for crushing and dispersion treatment, and after uniform mixing, a precursor material with a particle size D50 of 100 nm was obtained.

[0093] (5) The precursor material was evenly dispersed and spread in a crucible, placed in a high-temperature furnace under a nitrogen atmosphere, and heated to 300°C at a heating rate of 3°C / min, kept warm for 2 hours for a second sintering treatment, and cooled to room temperature at a cooling rate of 3°C / min. The material was crushed and sieved to obtain gray-white particles with a diameter of D 50 A new alkali metal-rich NASICON-type solid electrolyte Li 7.8 Al 0.3 Ti1.7 (PO4)3.

[0094] The novel alkali metal-rich NASICON solid electrolyte Li prepared in Example 1 7.8 Al 0.3 Ti 1.7 The actual picture of (PO4)3 is shown in Figure 2. It can be seen that the prepared material is off-white powder.

[0095] The novel alkali metal-rich NASICON solid electrolyte Li prepared in Example 1 7.8 Al 0.3 Ti 1.7 The XRD spectrum of (PO4)3, as shown in Figure 3, was tested by X-ray using a Cu-Kα target. It has diffraction peaks at 2θ diffraction angles = 20.8°, 22.2°, 23°, and 24.5°, characteristic peaks at 2θ diffraction angles = 33.3°, 33.8°, and 36.5°, and a weak impurity peak near 34°.

[0096] The novel alkali metal-rich NASICON solid electrolyte Li prepared in Example 1 7.8 Al 0.3 Ti 1.7 The main crystal structure of (PO4)3 belongs to the Pmnb space group, including the polyhedral structure of the Pmnb phase and the ball-and-stick structure of the Pmnb phase, as shown in the structural schematics of Figure 4(a) and Figure 4(b), respectively.

[0097] The novel alkali-metal-rich NASICON solid electrolyte prepared in this embodiment is used to assemble a lithium-ion all-solid-state battery using a conventional method, wherein lithium cobalt oxide is used as the positive electrode and lithium metal is used as the negative electrode. 7.8 Al 0.3 Ti 1.7 (PO4)3 was used as the electrolyte layer; test conditions: charge and discharge current 0.1A / g, charge cut-off voltage 4.2V, and discharge cut-off voltage 2V.

[0098] The electrochemical impedance spectroscopy (EIS) graph of the lithium-ion all-solid-state battery assembled in this embodiment is shown in FIG5 .

[0099] The cycle capacity curve of the lithium-ion all-solid-state battery assembled in this embodiment is shown in FIG6 , from which it can be seen that the cycle of the lithium-ion all-solid-state battery is relatively stable.

[0100] The test data of the lithium-ion all-solid-state battery assembled in this embodiment are detailed in Table 1.

[0101] Example 2

[0102] This embodiment provides a preparation process and performance test of a novel alkali metal-rich NASICON-type solid electrolyte. The specific preparation process is as follows.

[0103] (1) According to NASICON solid electrolyte Li 1.5 Ga 0.5 Ti 1.5 The raw materials are weighed in the stoichiometric ratio of (SiO4)3: A source material LiFSI, B source material SiO2, M source material Ga2(SO4)3, N source material dibutyl titanate (DBTDP), and alkali metal activator Li2O2.

[0104] Among them, the particle size D of LiFSI 50 The particle size of SiO2 is 30μm, D 50 The particle size D of Ga2(SO4)3 is 20nm 50 The particle size D of dibutyl titanate (DBTDP) is 50 μm. 50 The particle size of Li2O2 is 100nm. 50 50nm; NASICON solid electrolyte Li 1.5 Ga 0.5 Ti 1.5 The molar ratio of (SiO4)3 to Li2O2 is [1:0.5].

[0105] (2) Under a nitrogen atmosphere, the raw materials and alkali metal activator weighed in step (1) are added to a high-speed disperser in descending order of particle size, the stirring speed is set to 2000 rpm, and the mixture is stirred for 30 minutes after each addition, and stirred for another 1.5 hours after the last addition to mix uniformly to obtain a mixed material.

[0106] (3) The mixed material was evenly dispersed and spread in a crucible, placed in a high-temperature furnace under a nitrogen atmosphere, and heated to 500°C at a heating rate of 5°C / min, kept at that temperature for 6 hours, and subjected to the first high-temperature sintering treatment. The intermediate material was obtained after cooling to room temperature at a cooling rate of 5°C / min.

[0107] (4) Under a nitrogen atmosphere, the intermediate material was placed in a roller crusher for crushing and dispersion treatment, and after uniform mixing, a precursor material with a particle size D50 of 100 nm was obtained.

[0108] (5) The precursor material was evenly dispersed and spread in a crucible, placed in a high-temperature furnace under a nitrogen atmosphere, and heated to 400°C at a heating rate of 2°C / min, kept warm for 3 hours for a second sintering treatment, and cooled to room temperature at a cooling rate of 2°C / min. The material was crushed and sieved to obtain gray-white particles with a diameter of D 50 A new alkali metal-rich NASICON-type solid electrolyte Li2.5 Ga 0.5 Ti 1.5 (SiO4)3.

[0109] The novel alkali metal-rich NASICON solid electrolyte Li prepared in this example 2.5 Ga 0.5 Ti 1.5 The XRD spectrum of (SiO4)3, as shown in Figure 7, was tested by X-ray using a Cu-Kα target. It has diffraction peaks at 2θ diffraction angles of 20.8°, 22.4°, 23.3°, and 24.5°, characteristic peaks at 2θ diffraction angles of 33.5°, 33.9°, and 36.5°, and a weak impurity peak near 34°.

[0110] The novel alkali metal-rich NASICON solid electrolyte prepared in this example was used to assemble a lithium-ion all-solid-state battery using conventional methods and tested in the same manner as in Example 1. The test data are detailed in Table 1.

[0111] Example 3

[0112] This embodiment provides a preparation process and performance test of a novel alkali metal-rich NASICON-type solid electrolyte. The specific preparation process is as follows.

[0113] (1) According to NASICON solid electrolyte Li 1.5 Al 0.5 Ge 1.5 The raw materials are weighed in the stoichiometric ratio of (PO4)3: A source material LiH, B source material (NH2)2HPO4, M source material Al(NO3)3·9H2O, N source material GeCl4, and alkali metal activator NaCIO4.

[0114] Among them, the particle size D of LiH 50 The particle size D of (NH2)2HPO4 is 30μm 50 The particle size D of Al(NO3)3·9H2O is 20nm. 50 The particle size D of GeCl4 is 50 μm. 50 The particle size D of NaCIO4 is 100nm. 50 50nm; NASICON solid electrolyte Li 1.5 Al 0.5 Ge 1.5 The molar ratio of (PO4)3 to NaCIO4 is [1:2.5].

[0115] (2) Under an argon atmosphere, the raw materials and alkali metal activator weighed in step (1) are added to a high-speed disperser in descending order of particle size, the stirring speed is set to 1500 rpm, and the mixture is stirred for 20 minutes after each addition, and stirred for another hour after the last addition to mix uniformly to obtain a mixed material.

[0116] (3) The mixed material was evenly dispersed and spread in a crucible, placed in a high-temperature furnace under an argon atmosphere, and heated to 650°C at a heating rate of 3°C / min, kept at this temperature for 5 hours, and subjected to the first high-temperature sintering treatment. The intermediate material was obtained after cooling to room temperature at a cooling rate of 3°C / min.

[0117] (4) Under an argon atmosphere, the intermediate material is placed in a roller crusher for crushing and dispersion treatment, and after uniform mixing, a precursor material with a particle size D50 of 100 nm is obtained.

[0118] (5) The precursor material was evenly dispersed and spread in a crucible, placed in a high-temperature furnace under an argon atmosphere, and heated to 300°C at a heating rate of 3°C / min, kept warm for 2 hours for a second sintering treatment, and cooled to room temperature at a cooling rate of 3°C / min. The material was crushed and sieved to obtain gray-white particles with a diameter of D 50 A new alkali metal-rich NASICON-type solid electrolyte Li 1.5 Na 2.5 Al 0.5 Ge 1.5 (PO4)3.

[0119] The novel alkali metal-rich NASICON solid electrolyte Li prepared in this example 1.5 Na 2.5 Al 0.5 Ge 1.5 The XRD spectrum of (PO4)3, as shown in Figure 8, was tested by X-ray using a Cu-Kα target. It has diffraction peaks at 2θ diffraction angles = 20.4°, 22.3°, 23.3°, and 24.6°, characteristic peaks at 2θ diffraction angles = 33.4°, 33.6°, and 36.8°, and a weak impurity peak near 34°.

[0120] The novel alkali metal-rich NASICON solid electrolyte prepared in this example was used to assemble a lithium-ion all-solid-state battery using conventional methods and tested in the same manner as in Example 1. The test data are detailed in Table 1.

[0121] Example 4

[0122] This embodiment provides a preparation process and performance test of a novel alkali metal-rich NASICON-type solid electrolyte. The specific preparation process is as follows.

[0123] (1) According to NASICON solid electrolyte Li 1.3 Al 0.3 Ti 1.7 The raw materials are weighed in the stoichiometric ratio of (PO4)3: A source material Li2SO4, B source material (NH2)2HPO4, M source material Al(OH)3, N source material TiO2, and the alkali metal activator LiOH.

[0124] Among them, the particle size D of LiOH 50 200nm; NASICON solid electrolyte Li 1.3 Al 0.3 Ti 1.7 The molar ratio of (PO4)3 to LiOH is [1:6.5].

[0125] (2) Under a nitrogen atmosphere, the raw materials and alkali metal activator weighed in step (1) are added to a high-speed disperser in descending order of particle size, the stirring speed is set to 3000 rpm, and the mixture is stirred for 30 minutes after each addition, and stirred for another 2 hours after the last addition to mix uniformly to obtain a mixed material.

[0126] (3) The mixed material was evenly dispersed and spread in a crucible, placed in a high-temperature furnace under a nitrogen atmosphere, and heated to 600°C at a heating rate of 1°C / min, kept at that temperature for 6 hours, and subjected to the first high-temperature sintering treatment. The intermediate material was obtained after cooling to room temperature at a cooling rate of 3°C / min.

[0127] (4) Under a nitrogen atmosphere, the intermediate material was placed in a roller crusher for crushing and dispersion treatment, and after uniform mixing, a precursor material with a particle size D50 of 100 nm was obtained.

[0128] (5) The precursor material was evenly dispersed and spread in a crucible, placed in a high-temperature furnace under a nitrogen atmosphere, and heated to 500°C at a heating rate of 1°C / min, kept at that temperature for 4 hours for a second sintering treatment, and cooled to room temperature at a cooling rate of 2°C / min. The material was crushed and sieved to obtain gray-white particles with a diameter of D 50 A new alkali metal-rich NASICON-type solid electrolyte Li 7.8 Al 0.3 Ti 1.7 (PO4)3.

[0129] The novel alkali metal-rich NASICON solid electrolyte Li prepared in this example 7.8 Al 0.3 Ti 1.7The XRD spectrum of (PO4)3, as shown in Figure 9, was tested by X-ray using a Cu-Kα target. It has diffraction peaks at 2θ diffraction angles = 20.5°, 22.6°, 23.2°, and 24.4°, characteristic peaks at 2θ diffraction angles = 33.5°, 33.6°, and 36.9°, and a weak impurity peak near 34°.

[0130] The novel alkali metal-rich NASICON solid electrolyte prepared in this example was used to assemble a lithium-ion all-solid-state battery using conventional methods and tested in the same manner as in Example 1. The test data are detailed in Table 1.

[0131] Example 5

[0132] This embodiment provides a preparation process and performance test of a novel alkali metal-rich NASICON-type solid electrolyte. The specific preparation process is as follows.

[0133] (1) According to NASICON solid electrolyte K 1.3 Mg 0.3 Zr 1.7 The raw materials are weighed in the stoichiometric ratio of (SeO4)3: A source material KNO3, B source material SeO2, M source material Mg(NO3)2, N source material ZrSO4, and alkali metal activator K2C2O4.

[0134] Among them, the particle size D of K2C2O4 50 100nm; NASICON solid electrolyte K 1.3 Mg 0.3 Zr 1.7 The molar ratio of (SeO4)3 to K2C2O4 is [1:2].

[0135] (2) Under a nitrogen atmosphere, the raw materials and alkali metal activator weighed in step (1) are added to a high-speed disperser in descending order of particle size, the stirring speed is set to 3000 rpm, and the mixture is stirred for 30 minutes after each addition, and stirred for another 2 hours after the last addition to mix uniformly to obtain a mixed material.

[0136] (3) The mixed material was evenly dispersed and spread in a crucible, placed in a high-temperature furnace under a nitrogen atmosphere, and heated to 600°C at a heating rate of 1°C / min, kept at that temperature for 6 hours, and subjected to the first high-temperature sintering treatment. The intermediate material was obtained after cooling to room temperature at a cooling rate of 3°C / min.

[0137] (4) Under a nitrogen atmosphere, the intermediate material was placed in a roller crusher for crushing and dispersion treatment, and after uniform mixing, a precursor material with a particle size D50 of 100 nm was obtained.

[0138] (5) The precursor material was evenly dispersed and spread in a crucible, placed in a high-temperature furnace under a nitrogen atmosphere, and heated to 500°C at a heating rate of 1°C / min, kept at that temperature for 4 hours for a second sintering treatment, and cooled to room temperature at a cooling rate of 2°C / min. The material was crushed and sieved to obtain gray-white particles with a diameter of D 50 A new alkali metal-rich NASICON solid electrolyte K with a thickness of 100 nm 5.3 Mg 0.3 Zr 1.7 (SeO4)3.

[0139] The novel alkali metal-rich NASICON solid electrolyte K prepared in this embodiment 5.3 Mg 0.3 Zr 1.7 The XRD spectrum of (SeO4)3, as shown in Figure 10, was tested by X-ray using a Cu-Kα target. It has diffraction peaks at 2θ diffraction angles of 20.6°, 22.4°, 23.2°, and 24.7°, characteristic peaks at 2θ diffraction angles of 33.3°, 33.5°, and 36.7°, and a weak impurity peak near 34°.

[0140] The novel alkali metal-rich NASICON solid electrolyte K prepared in this embodiment 5.3 Mg 0.3 Zr 1.7 (SeO4)3 was assembled using conventional methods to prepare a potassium ion all-solid-state battery, in which potassium cobalt oxide was used as the positive electrode active material to prepare the positive electrode, potassium metal was used as the negative electrode, and a new alkali metal-rich NASICON solid electrolyte K 5.3 Mg 0.3 Zr 1.7 (SeO4)3 was used as the electrolyte layer; test conditions: charge and discharge current 0.1 A / g, charge cut-off voltage 4.2 V, discharge cut-off voltage 2 V. The test data are detailed in Table 1.

[0141] Example 6

[0142] This embodiment provides a preparation process and performance test of a novel alkali metal-rich NASICON-type solid electrolyte. The specific preparation process is as follows.

[0143] (1) According to the NASICON solid electrolyte Na3Al 0.3 Ti 1.7 The raw materials are weighed in the stoichiometric ratio of (SiO4)3: A source material NaCIO4, B source material SiH4, M source material Al(OH)3, N source material Ti(NO3)4, and alkali metal activator CH2COONa.

[0144] Among them, the particle size D of CH2COONa50 10μm; NASICON type solid electrolyte Na3Al 0.3 Ti 1.7 The molar ratio of (PO4)3 to CH2COONa is [1:6.5].

[0145] (2) Under a nitrogen atmosphere, the raw materials and alkali metal activator weighed in step (1) are added to a high-speed disperser in descending order of particle size, the stirring speed is set to 3000 rpm, and the mixture is stirred for 30 minutes after each addition, and stirred for another 2 hours after the last addition to mix uniformly to obtain a mixed material.

[0146] (3) The mixed material was evenly dispersed and spread in a crucible, placed in a high-temperature furnace under a nitrogen atmosphere, and heated to 600°C at a heating rate of 1°C / min, kept at that temperature for 6 hours, and subjected to the first high-temperature sintering treatment. The intermediate material was obtained after cooling to room temperature at a cooling rate of 3°C / min.

[0147] (4) Under a nitrogen atmosphere, the intermediate material was placed in a roller crusher for crushing and dispersion treatment, and after uniform mixing, a precursor material with a particle size D50 of 100 nm was obtained.

[0148] (5) The precursor material was evenly dispersed and spread in a crucible, placed in a high-temperature furnace under a nitrogen atmosphere, and heated to 500°C at a heating rate of 1°C / min, kept at that temperature for 4 hours for a second sintering treatment, and cooled to room temperature at a cooling rate of 2°C / min. The material was crushed and sieved to obtain gray-white particles with a diameter of D 50 A new alkali metal-rich NASICON solid electrolyte Na 9.5 Al 0.3 Ti 1.7 (SiO4)3.

[0149] The novel alkali metal-rich NASICON solid electrolyte Na prepared in this embodiment 9.5 Al 0.3 Ti 1.7 The XRD spectrum of (SiO4)3, as shown in Figure 11, was tested by X-ray using a Cu-Kα target. It has diffraction peaks at diffraction angles of 2θ = 20.9°, 22.4°, 22.8°, and 24.3°, characteristic peaks at 2θ diffraction angles of 33.5°, 33.7°, and 36.8°, and a weak impurity peak near 34°.

[0150] The novel alkali metal-rich NASICON solid electrolyte Na prepared in this embodiment 9.5 Al 0.3 Ti 1.7(SiO4)3 was assembled using conventional methods to prepare a sodium ion all-solid-state battery, in which sodium nickel cobalt manganese oxide (NCM) was used as the positive electrode active material to prepare the positive electrode, sodium metal sheet was used as the negative electrode, and a new alkali metal-rich NASICON solid electrolyte Na 9.5 Al 0.3 Ti 1.7 (SiO4)3 was used as the electrolyte layer; test conditions: charge and discharge current 0.1 A / g, charge cut-off voltage 4.2 V, discharge cut-off voltage 2 V. Detailed test data is shown in Table 1.

[0151] To better illustrate the effects of the embodiments of the present invention, Comparative Example 1 is compared with the above Example 1, Comparative Example 2 is compared with the above Example 5, and Comparative Example 3 is compared with the above Example 6.

[0152] Comparative Example 1

[0153] The original NASICON solid electrolyte lithium aluminum titanium phosphate Li 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP) is used as comparative example 1, and its XRD pattern is shown in FIG3 . It can be seen that the original NASICON solid electrolyte Li 1.3 Al 0.3 Ti 1.7 The diffraction peak of (PO4)3(LATP) is different from that of the new alkali metal-rich NASICON-type solid electrolyte in Example 1, indicating that the crystal structure of the new alkali metal-rich NASICON-type solid electrolyte is different from that of the NASICON-type solid electrolyte LATP. The crystal structure of the solid electrolyte prepared by the present invention is similar to but not a NASICON-type solid electrolyte, and it is a new type of solid electrolyte.

[0154] An all-solid-state battery was assembled using LATP and tested in the same manner as in Example 1. The electrochemical impedance spectrum (EIS) of the assembled lithium-ion all-solid-state battery is shown in FIG5 . It can be seen that the impedance of Example 1 is smaller than that of the battery in Comparative Example 1, indicating that compared with the original NASICON-type solid electrolyte LATP in Comparative Example 1, the novel alkali metal-rich NASICON-type solid electrolyte prepared in Example 1 can greatly reduce the interfacial impedance in the electrochemical reaction of the battery, thereby inhibiting the occurrence of interfacial side reactions. The test data of the lithium-ion all-solid-state battery assembled in this comparative example are detailed in Table 1.

[0155] Comparative Example 2

[0156] The original NASICON solid electrolyte K of Example 5 1.3 Mg 0.3 Zr 1.7(SeO4)3 was used as comparative example 2 to assemble a potassium ion all-solid-state battery and perform testing in the same manner as in Example 5. The test data of the assembled potassium ion all-solid-state battery are detailed in Table 1.

[0157] Comparative Example 3

[0158] The original NASICON solid electrolyte Na3Al 0.3 Ti 1.7 (SiO4)3 was used as comparative example 3 to assemble a sodium ion all-solid-state battery and perform tests in the same manner as in Example 6. The test data of the assembled sodium ion all-solid-state battery are detailed in Table 1.

[0159] Table 1 summarizes the test data of the batteries assembled in Examples 1-6 and Comparative Examples 1-3:

[0160] By comparing the test data in Table 1, it can be seen that the ionic conductivity, AC impedance and cycle capacity retention rate after 500 cycles of the lithium ion all-solid-state battery of Example 1 are better than those of the battery of Comparative Example 1. Similarly, the potassium ion all-solid-state battery of Example 5 is also better than that of Comparative Example 2, and the sodium ion all-solid-state battery of Example 6 is also better than that of Comparative Example 3. This is because the battery assembled in the embodiment of the present invention contains a new alkali metal-rich NASICON-type solid electrolyte, which can significantly reduce the interfacial impedance of the battery, improve the carrier transport efficiency, and improve the cycle stability of the battery.

[0161] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A novel alkali metal-rich NASICON-type solid electrolyte, characterized in that: The chemical formula of the novel alkali metal-rich NASICON solid electrolyte is A 1+x+y M x N 2-x (BO4)3, wherein 0≤x≤3, 0≤y≤26; A is any one of Li, Na, K, Mg, and Ca; B is one or more of B, P, Si, S, Se, As, and Te; M is one or more of Al, Ga, Cd, Mn, Co, Ni, Zn, Fe, Sc, Cr, In, Y, and Ln; N is one or more of Ti, Sn, Ge, Zr, Hf, V, Nb, Ta, and Sb; The novel alkali metal-rich NASICON solid electrolyte is prepared by adding a particle size D 50 It is obtained by reacting 1nm-10μm alkali metal activators with other raw materials; The alkali metal activator includes any one of a lithium activator, a sodium activator or a potassium activator; The lithium activator includes one or more of LiH, Li2S, Li2SO4, C2H5LiO, CH3LiO, Li2C2O4, a mixture of lithium-aromatic hydrocarbon-ether solvents, LiClO4, LiSO, LiAlSO, and LiBF4; the mixture of lithium-aromatic hydrocarbon-ether solvents includes one or more of lithium-biphenyl-ethylene glycol dimethyl ether mixture, lithium-biphenyl-tetrahydrofuran mixture, lithium-naphthalene-tetrahydrofuran mixture, and lithium-naphthalene-dioxolane mixture; The sodium activator includes one or more of NaH, Na2O, Na2O2, Na2S, NaOH, Na2CO3, CH3COONa, Na2SO4, NaCl, NaF, Na3PO4, C2H5NaO, CH3NaO, Na2C2O4, a mixture of sodium-aromatic hydrocarbon-ether solvents, NaAlSO, NaTFSI, and NaFSI; the mixture of sodium-aromatic hydrocarbon-ether solvents includes one or more of a sodium-naphthalene-tetrahydrofuran mixture, a sodium-naphthalene-dioxolane mixture, a sodium-naphthalene-tetrahydrofuran mixture, and a sodium-biphenyl-tetrahydrofuran mixture; The potassium activator includes: one or more of KH, K2O, K2O2, K2S, KOH, K2CO3, KF, K3PO4, C2H5KO, CH3KO, K2C2O4, a mixture of potassium-aromatic hydrocarbon-ether solvents, KPF6, KClO4, KSO, KAlSO, KBF4, KTFSI, and KFSI; the mixture of potassium-aromatic hydrocarbon-ether solvents includes: one or more of a potassium-naphthalene-tetrahydrofuran mixture, a potassium-naphthalene-dioxolane mixture, a potassium-biphenyl-ethylene glycol dimethyl ether mixture, and a potassium-biphenyl-tetrahydrofuran mixture; The novel alkali metal-rich NASICON solid electrolyte is subjected to X-ray testing using a Cu-Kα target, and has diffraction peaks at 2θ=20.8±0.5°, 22.2±0.5°, 23±0.5°, and 24.5±0.5°; the 2θ of the diffraction peak has two weak diffraction peaks between 21.7° and 23.5°, and 2θ=33.3±0.5°, 33.8±0.5°, and 24.5±0.5° between 32° and 37°. There are three characteristic peaks at 36.5±0.5°, and a weak impurity peak near 34°; The diffraction peak intensities at the positions of 2θ=20.8±0.5°, 22.2±0.5°, 23±0.5°, 24.5±0.5°, 33.3±0.5°, 33.8±0.5°, and 36.5±0.5° are set as I1, I2, I3, I4, I5, I6, and I7, respectively, wherein the peak intensity ratio of I1:I4 is 0.1:1-1:1, the peak intensity ratio of I2:I3 is 0.1:1-2:1, the peak intensity ratio between I5:I6 is 1:2-2:1, and the peak intensity ratio between I5:I7 is 1:2-2:1; The main crystal structure of the novel alkali metal-rich NASICON-type solid electrolyte belongs to the Pmnb space group and the P-43n space group, among which the Pmnb space group is dominant.

2. The novel alkali metal-rich NASICON solid electrolyte according to claim 1, characterized in that: When x=0.3 or x=0.5, 0.5≤y≤26.

3. The novel alkali metal-rich NASICON solid electrolyte according to claim 1, characterized in that: The novel alkali metal-rich NASICON solid electrolyte has an appearance of off-white powder, and the lightness L in the Lab color model ranges from 0≤L<15.

4. A method for preparing the novel alkali metal-rich NASICON solid electrolyte according to any one of claims 1 to 3, characterized in that: The preparation method comprises: Weigh the raw materials according to the stoichiometric ratio of the NASICON solid electrolyte: A source material, B source material, M source material, N source material, and weigh the alkali metal activator; Under protective atmosphere, the raw materials and particle size D 50 Alkali metal activators with particle sizes ranging from 1 nm to 10 μm are added into a mixing device in descending order of particle size and mixed evenly to obtain a mixed material; The mixed material is evenly dispersed and spread in a crucible, and placed in a high-temperature furnace under a protective atmosphere for a first high-temperature sintering treatment, and an intermediate material is obtained after the temperature is cooled to room temperature for the first time; Under a protective atmosphere, the intermediate material is placed in a pulverizer for crushing and dispersion, and the precursor material is obtained after being mixed evenly; The precursor material is evenly dispersed and spread in a crucible, and placed in a high-temperature furnace under a protective atmosphere for a second sintering treatment. After cooling to room temperature for the second time, the material is crushed and sieved to obtain a novel alkali metal-rich NASICON solid electrolyte; The source material A includes: Li2O, Li2O2, LiOH, Li2CO3, CH3COOLi, LiNO3, LiPF6, LiAsF6, LiBF4, LiFSI, LiTFSI, LiCF3SO3, LiCF3SO3·LiOAc, LiC2H3O2, LiCl, LiF, Li3PO4, lithium bis(oxalatoborate) LiBOB, lithium difluorooxalatoborate LiDFOB, Li2B4O7, NaPF6, NaClO4, NaAlClh, NaFeClh, NaSO, NaBF4, NaNO3, NaPOFA, KCl, KNO3, One or more of KH2PO4, K2SO4, CH3COOK; The B source material includes one or more of H2PO4, NH2H2PO4, (NH2)2HPO4, SiO2, SiH4, CH3SiH3, CS2, P2S3, SeO2, and CdSe; The M source materials include: Al2O3, Al(OH)3, AlOOH, Al2(CO3)3, C9H 21 One or more of AlO3, Al(NO3)3·9H2O, Al[OOCH3(OH)2]·xH2O, GaCl3, GaBr3, GaI3, Ga(NO3)3, Ga2(SO4)3; The N source materials include: TiCl4, Ti(NO3)4, isobutyl titanate IPT, dibutyl titanate DBTDP, tetrabutyl titanate TBT, C 16 H 36 One or more of O4Ti, Ti(n-C3H7O)4, Ti(OC4H9)4, ZrO2, ZrSiO4, ZrSO4, ZrOCl2, ZrC, ZrCO3, ZrB, ZrB2; The alkali metal activator includes any one of a lithium activator, a sodium activator or a potassium activator; wherein the lithium activator includes one or more of LiH, Li2S, Li2SO4, C2H5LiO, CH3LiO, Li2C2O4, a mixture of lithium-aromatic hydrocarbon-ether solvents, LiCIO4, LiSO, LiAlSO, and LiBF4; the mixture of lithium-aromatic hydrocarbon-ether solvents includes one or more of a lithium-biphenyl-ethylene glycol dimethyl ether mixture, a lithium-biphenyl-tetrahydrofuran mixture, a lithium-naphthalene-tetrahydrofuran mixture, and a lithium-naphthalene-dioxolane mixture; The sodium activator includes one or more of NaH, Na2O, Na2O2, Na2S, NaOH, Na2CO3, CH3COONa, Na2SO4, NaCl, NaF, Na3PO4, C2H5NaO, CH3NaO, Na2C2O4, a mixture of sodium-aromatic hydrocarbon-ether solvents, NaAlSO, NaTFSI, and NaFSI; the mixture of sodium-aromatic hydrocarbon-ether solvents includes one or more of a sodium-naphthalene-tetrahydrofuran mixture, a sodium-naphthalene-dioxolane mixture, a sodium-naphthalene-tetrahydrofuran mixture, and a sodium-biphenyl-tetrahydrofuran mixture; The potassium activator includes: KH, K2O, K2O2, K2S, KOH, K2CO3, KF, K3PO4, C2H5KO, CH3KO, K2C2O4, a mixture of potassium-aromatic hydrocarbon-ether solvents, KPF6, KClO4, KSO, KAlSO, KBF4, KNO 3、 One or more of KTFSI and KFSI; the mixture of potassium-aromatic hydrocarbon-ether solvents includes one or more of potassium-naphthalene-tetrahydrofuran mixture, potassium-naphthalene-dioxolane mixture, potassium-biphenyl-ethylene glycol dimethyl ether mixture, and potassium-biphenyl-tetrahydrofuran mixture; The conditions for the first high-temperature sintering treatment are specifically as follows: heating to 500°C-850°C at a heating rate of 1°C / min-3°C / min, and keeping warm for 4 hours-7 hours; the conditions for the second sintering treatment are specifically as follows: heating to 300°C-650°C at a heating rate of 1°C / min-3°C / min, and keeping warm for 2 hours-6 hours.

5. The preparation method according to claim 4, characterized in that: The particle size D50 of the alkali metal activator is between 1 nm and 10 μm; the molar ratio of the NASICON solid electrolyte to the alkali metal activator is [1:0.5]-[1:6.5].

6. The preparation method according to claim 4, characterized in that: The protective atmosphere includes one or more of nitrogen, argon and hydrogen; The mixing device is a high-speed disperser, and the stirring speed is between 1500rpm-5000rpm; the specific method of mixing uniformly is: stirring for 20min-60min after each addition, and stirring for 1 hour-3 hours after the last addition; The cooling rates of the first cooling to room temperature and the second cooling to room temperature are both 1°C / min-5°C / min.

7. An application of the novel alkali metal-rich NASICON solid electrolyte according to any one of claims 1 to 3, characterized in that: The novel alkali metal-rich NASICON solid electrolyte is used in one or more of an electrolyte, a separator, a positive electrode material additive, a negative electrode material additive, and an electrolyte additive.

8. A secondary battery, characterized in that: The secondary battery comprises one or more of the electrolyte, separator, positive electrode material additive, negative electrode material additive, and electrolyte additive as described in claim 7.

9. The secondary battery according to claim 8, characterized in that: The secondary battery includes any one of a lithium ion battery, a sodium ion battery, and a potassium ion battery.

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