A solid electrolyte with high ionic conductivity and its preparation method

Abstract

This application relates to the field of solid-state battery materials and discloses a solid electrolyte with high ionic conductivity and its preparation method. The solid electrolyte is prepared by reacting a precursor mixture. The raw materials, based on the molar amount of metal atoms in the system, include: 1% to 5% heterogeneous metal dopant, 2% to 8% niobium pentachloride, 92% to 98% niobium pentoxide, and anhydrous sodium chloride. The preparation method involves loading the precursor into a closed reactor with a set back pressure, heating it to a medium temperature and holding it at a first heating rate to generate a gas-phase transport medium, and then heating it to the main reaction temperature at a lower second heating rate to drive anion disordering. After the reaction, rapid freezing and condensation using gas-solid fluidization is performed to obtain a metastable phase. This invention achieves disordered lattice anion distribution through the synergistic effect of gas-phase transport and heterogeneous doping, combined with stepped temperature control and fluidized bed rapid cooling, thus broadening the three-dimensional ion transport channels and effectively improving the room-temperature ionic conductivity and electrochemical stability of the electrolyte.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery materials technology, specifically to a solid electrolyte with high ionic conductivity and its preparation method. Background Technology

[0002] With the development of solid-state battery technology, solid-state electrolytes, as core components, directly determine the safety and energy density of the battery. Among various solid-state electrolyte systems, niobium-based oxyhalide solid-state electrolytes have attracted attention due to their unique crystal structure and good theoretical ion transport characteristics. However, existing conventional niobium-based oxyhalide solid-state electrolytes still have performance shortcomings in practical applications.

[0003] At the microstructure level, due to limitations of conventional solid-state synthesis processes, oxygen ions and halide anions tend to undergo thermodynamically driven ordered arrangement within the crystal lattice, resulting in obstructed three-dimensional ion transport channels and, macroscopically, insufficient ion conductivity at room temperature. Simultaneously, this ordered lattice structure is ill-suited to high-voltage charge-discharge conditions; halide anions readily precipitate in oxidizing environments, triggering framework degradation and leading to poor high-voltage electrochemical stability of the material.

[0004] At the material synthesis process level, traditional preparation methods typically employ natural cooling or conventional furnace cooling after the reaction. This relatively slow cooling process provides the system with time for thermal diffusion and dephase transition, making it difficult to effectively retain the highly active metastable phase generated at high temperatures, which is rich in cation vacancies and has a disordered distribution of anions. This leads to the aggregation of structural defects in local microregions of the solid electrolyte, resulting in a significant increase in charge transfer impedance at the electrode interface after battery assembly, thereby limiting the overall electrochemical performance of the solid-state battery. Summary of the Invention

[0005] The technical problem solved by this invention is that conventional niobium-based oxyhalide solid electrolytes have insufficient room temperature ionic conductivity, poor high-voltage electrochemical stability, and high charge transfer impedance at the electrode interface.

[0006] To address the above problems, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a solid electrolyte with high ionic conductivity, employing the following technical solution:

[0008] A solid electrolyte with high ionic conductivity, said solid electrolyte being prepared by reacting a precursor mixture.

[0009] Based on the total molar amount of total metal atoms in the system, the precursor mixture contains the following components: a heterogeneous metal dopant source, which provides heterogeneous metal atoms accounting for 1% to 5% of the total molar amount of metal atoms; niobium pentachloride, which provides niobium atoms accounting for 2% to 8% of the total molar amount of niobium atoms in the system; and niobium pentoxide, which provides the remaining 92% to 98% of the niobium atoms in the system.

[0010] Anhydrous sodium chloride results in a molar ratio of sodium atoms to total metal atoms of 1:1.

[0011] By adopting the above technical solution, the precursor mixture undergoes a phase evolution during heating. The specific reaction mechanism and physicochemical evolution process include the following steps:

[0012] Process 1: Generation of the gas-phase transport medium. As the system temperature increases, niobium pentachloride in the raw material system undergoes a phase transformation and enters the gaseous state.

[0013] In a controlled, closed reaction environment, sublimated niobium pentachloride gas fills the gaps between particles, forming a gas-solid mass transfer network.

[0014] Process 2: Homogeneous diffusion of heterogeneous metals. High-valence transition metal cations overcome the high diffusion energy barrier present in pure solid-phase contact by using gaseous niobium pentachloride as a transport carrier.

[0015] Heterogeneous metal elements are dispersed and embedded in the basic lattice framework constructed of niobium pentoxide to achieve homogeneous solid solution doping.

[0016] Process 3: Electronic Structure Regulation and Lattice Disordering. The introduction of high-valence metal ions modulates the Fermi level of the host niobium-based oxyhalide framework, delaying structural degradation caused by the oxidation and precipitation of halide anions. In this process, oxygen and chlorine atoms undergo long-range rearrangement and form statistically random occupancy sites on the lattice polyhedrals.

[0017] The system undergoes lattice distortion, generating a metastable phase with high ionic conductivity and disordered anion distribution.

[0018] This disordered structure eliminates the defect aggregation phenomenon in local micro-regions, expands the three-dimensional ion transport channels inside the material, and improves the overall high-voltage electrochemical stability window.

[0019] Preferably, the heterogeneous metal doping source is tungsten trioxide or tantalum pentoxide. When the heterogeneous metal doping source is tungsten trioxide, tungsten atoms account for 3% to 5% of the total molar amount of metal atoms, corresponding to niobium atoms provided by niobium pentachloride accounting for 5% to 8% of the total molar amount of niobium atoms in the system.

[0020] When the heterometallic doping source is tantalum pentoxide, tantalum atoms account for 1% of the total molar amount of metal atoms, corresponding to niobium atoms provided by niobium pentachloride accounting for 2% of the total molar amount of niobium atoms in the system.

[0021] By adopting the above technical solution, the heteroatoms provided by tungsten trioxide and tantalum pentoxide have different ionic radius parameters.

[0022] Tungsten trioxide and tantalum pentoxide provide heteroatoms with different ionic radius parameters.

[0023] The specific doping ratio and the amount of niobium pentachloride gas phase carrier are matched to cause the product cell volume to shrink appropriately. The doping within a specific range causes the lattice to shift regularly, so that the doping element occupies the core site of the framework lattice, thereby ensuring the continuity of sodium ion transitions across grain boundaries.

[0024] Secondly, the present invention provides a method for preparing a solid electrolyte with high ionic conductivity, employing the following technical solution:

[0025] A method for preparing a solid electrolyte with high ionic conductivity includes the following steps: loading a precursor mixture into a closed continuous tubular reactor, sealing the reactor and connecting a back pressure control valve, and setting the system's safe exhaust absolute pressure threshold.

[0026] The reactor is heated to the intermediate temperature range at the first heating rate and kept at a constant temperature and pressure to maintain the absolute pressure inside the reactor in a slightly positive state.

[0027] After the medium-temperature isothermal holding period is completed, the reactor is heated to the main reaction temperature at a second heating rate and held at that temperature without compromising the reactor's airtightness and back pressure setting.

[0028] After the main reaction is kept at a constant temperature, the powder material at the main reaction temperature is transferred to a closed fluidized cooling chamber. Cooling gas is simultaneously blown into the bottom of the cooling chamber to make the powder in a gas-solid fluidized state. The powder is cooled and frozen within a preset time, and the cooled solid powder is collected to obtain a solid electrolyte.

[0029] By adopting the above technical solutions, the material synthesis stage follows a specific kinetic and thermodynamic control mechanism:

[0030] Phase 1: Physical vapor phase confinement. The back pressure control system suppresses excessive volatilization of low-boiling-point substances such as niobium pentachloride.

[0031] The reactor is under a slightly positive pressure, maintaining the initial designed ratio of oxygen and chlorine elements within the system to prevent the outflow of gaseous materials from causing an imbalance in the stoichiometric ratio of the solid products. Second stage: Reaction kinetic relaxation control.

[0032] The main reaction is carried out at a second heating rate lower than that of the first stage. Slow heating provides structural relaxation time for oxygen and chloride ions to overcome their thermodynamic separation tendency. This mechanism drives the disordered assembly of anions at the vertices of the polyhedron, preventing the closure of lattice channels due to localized ordered aggregation of anions, and constructing an isotropic three-dimensional ion transport network.

[0033] The third stage: thermodynamic phase freezing. At the reaction endpoint, a gas-solid fluidized bed quenching process is initiated. The cooling gas stream suspends the high-temperature powder in a fluidized state, increasing the heat exchange area between the particles and the cooling medium and reducing heat transfer hysteresis between particles. Rapid cooling within 10 minutes blocks the thermal diffusion dephase transition pathway of atoms, preserving the disordered characteristics and cation vacancy defects generated in the main reaction stage. The resulting metastable phase contains ion transition sites, providing a stable sodium ion supply rate in a charge-discharge environment.

[0034] Preferably, the first heating rate is 2.0 to 5.0 degrees Celsius per minute, the medium temperature range is 200 to 250 degrees Celsius, and the constant temperature and pressure holding time is 2 to 4 hours.

[0035] The second heating rate is 1.0 to 2.0 degrees Celsius per minute, the main reaction temperature is 500 to 700 degrees Celsius, and the holding time is 6 to 12 hours.

[0036] By adopting the above technical solution, the stepped heating mode provides corresponding driving force at different stages of physicochemical changes.

[0037] The initial heating rate ensures that niobium pentachloride can sublimate and establish a stable gas phase partial pressure.

[0038] The second heating rate slows down the lattice rearrangement rate, avoids space charge layer polarization at the interface from a kinetic perspective, promotes phase transition uniformity, and improves the interface adaptability and long-term capacity retention of the prepared solid electrolyte during charge-discharge cycles.

[0039] This invention provides a solid electrolyte with high ionic conductivity and its preparation method. It has the following beneficial effects:

[0040] 1. This invention achieves homogeneous solid solution doping of high-valence transition metal cations by introducing a heterogeneous metal doping source in conjunction with niobium pentachloride gas-phase transport medium. This doping mechanism modulates the Fermi level of the main framework, drives oxygen and chlorine atoms to occupy disordered sites on the lattice polyhedral sites and induces lattice distortion, thereby broadening the three-dimensional ion transport channels inside the material and improving the room temperature ion conductivity of the solid electrolyte.

[0041] 2. This invention employs a process combining a closed micro-positive pressure environment with stepwise temperature control. The pressure holding in the first stage suppresses the volatilization of low-boiling-point substances and maintains the stoichiometric ratio of halogen elements in the product. The second stage uses a low heating rate as the main reaction to provide sufficient structural relaxation time. This thermodynamic and kinetic synergistic control mechanism avoids the aggregation of local defects and improves the high-voltage electrochemical stability window of the material.

[0042] 3. This invention introduces a gas-solid fluidized rapid cooling process at the end of the reaction. The cooling gas is used to make the high-temperature powder fluidized and suspended, which increases the heat exchange area of ​​the particles to achieve rapid cooling. This rapid cooling process blocks the thermal diffusion dephase transformation path of atoms, effectively freezes and retains the disordered metastable phase and cation vacancy defects generated in the high-temperature stage, and reduces the charge transfer impedance at the interface between the solid electrolyte and the electrode. Attached Figure Description

[0043] Figure 1 The image shows the trend of unit cell volume variation and local X-ray diffraction comparison of the sample of this invention.

[0044] Figure 2 This is the full X-ray diffraction pattern of the sample of this invention;

[0045] Figure 3 The AC impedance spectrum fitting curve of the sample of this invention;

[0046] Figure 4 This is a comparison chart of the room temperature conductivity and air stability of the samples of this invention;

[0047] Figure 5 The graphs show the linear scan voltammetry and symmetrical cell test results of the sample of this invention.

[0048] Figure 6 This is a graph showing the rate and long-cycle performance test results of the all-solid-state battery of this invention. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] The following detailed description, in conjunction with specific embodiments and examples, further illustrates the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art can modify or make equivalent substitutions to the following embodiments without departing from the concept of the present invention, and all such modifications and substitutions should be included within the scope of protection of the present invention.

[0051] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher products in the art.

[0052] Niobium pentoxide is a commercially available product in the field, an analytical grade reagent with a purity of ≥99.5%, CAS number 1313-96-8, which serves as the basic lattice framework precursor material for providing niobium source and part of oxygen source in this invention;

[0053] Niobium pentachloride is a commercially available product in the field, an analytical grade reagent with a purity of ≥99.9%, CAS number 10026-12-7, and a boiling point of 248.2℃. It is used in this invention as a gas-phase transport agent that provides self-generated pressure and chlorine source, as well as a supplementary skeletal precursor material.

[0054] Anhydrous sodium chloride is a commercially available product in the field, a superior grade reagent with a purity of ≥99.9%, CAS number 7647-14-5. It is used after being vacuum dried at 120°C for 12 hours to remove surface adsorbed water, and serves as a precursor material for providing sodium source and main chlorine source in this invention.

[0055] Tungsten trioxide is a commercially available product in the field, an analytical grade reagent with a purity of ≥99.5%, CAS number 1314-35-8, which serves as the heterometallic precursor source for hexavalent tungsten cation doping in this invention.

[0056] Tantalum pentoxide is a commercially available product in the field, an analytical grade reagent with a purity of ≥99.5%, CAS number 1314-61-0, which serves as the heterometallic precursor source for pentavalent tantalum cation doping in this invention.

[0057] Preparation Example 1:

[0058] This preparation example provides a method for preparing a precursor mixture containing 3 mol% tungsten doping and 5% niobium pentachloride in the total niobium molar amount, comprising the following steps:

[0059] In a glove box with a dew point temperature below -40°C and filled with high-purity argon gas of not less than 99.999%, tungsten trioxide is accurately weighed so that tungsten atoms account for 3% of the total molar amount of metal atoms in the system, based on the total molar amount of metal atoms in the system.

[0060] Accurately weigh niobium pentachloride so that it provides 5% of the total molar amount of niobium atoms in the system; accurately weigh niobium pentoxide to provide the remaining 95% of the niobium atoms;

[0061] Accurately weigh anhydrous sodium chloride so that the molar ratio of sodium atoms to total metal atoms is 1:1.

[0062] The weighed anhydrous sodium chloride, niobium pentoxide, niobium pentachloride and tungsten trioxide powder were put into a ball mill jar lined with zirconium oxide, and zirconium oxide grinding balls were added. The ball-to-material mass ratio was set to 15:1.

[0063] After sealing the ball mill jar, it is placed in a planetary ball mill for dry mechanical mixing. The rotation speed is set to 400 rpm and the continuous grinding time is 2 hours. After grinding, the material is collected to obtain micron-sized precursor uniformly mixed powder.

[0064] Preparation Example 2:

[0065] This preparation example provides a method for preparing a precursor mixture containing 1 mol% tantalum doping and 2% niobium pentachloride in the total niobium molar amount, including the following steps:

[0066] In a glove box with a dew point temperature below -40℃ and filled with high-purity argon gas with a purity of not less than 99.999%, tantalum pentoxide is accurately weighed so that tantalum atoms account for 1% of the total molar amount of metal atoms in the system, based on the total molar amount of metal atoms in the system.

[0067] Accurately weigh niobium pentachloride so that it provides 2% of the total molar amount of niobium atoms in the system;

[0068] Accurately weigh niobium pentoxide to provide the remaining 98% of niobium atoms; accurately weigh anhydrous sodium chloride to make the molar ratio of sodium atoms to total metal atoms 1:1.

[0069] The weighed anhydrous sodium chloride, niobium pentoxide, niobium pentachloride and tantalum pentoxide powders were put into a ball mill jar lined with zirconium oxide, and zirconium oxide grinding balls were added. The ball-to-material mass ratio was set to 10:1.

[0070] After sealing the ball mill jar, it is placed in a planetary ball mill for dry mechanical mixing. The rotation speed is set to 300 rpm and the continuous grinding time is 3 hours. After grinding, the material is collected to obtain micron-sized precursor uniformly mixed powder.

[0071] Preparation Example 3:

[0072] This preparation example provides a method for preparing a precursor mixture containing 5 mol% tungsten doping and 8% niobium pentachloride in the total niobium molar amount, including the following steps:

[0073] In a glove box with a dew point temperature below -40℃ and filled with high-purity argon gas with a purity of not less than 99.999%, tungsten trioxide is accurately weighed so that tungsten atoms account for 5% of the total molar amount of metal atoms in the system, based on the total molar amount of metal atoms in the system.

[0074] Accurately weigh niobium pentachloride so that it provides 8% of the total molar amount of niobium atoms in the system;

[0075] Accurately weigh niobium pentoxide to provide the remaining 92% of niobium atoms; accurately weigh anhydrous sodium chloride to make the molar ratio of sodium atoms to total metal atoms 1:1.

[0076] The weighed anhydrous sodium chloride, niobium pentoxide, niobium pentachloride and tungsten trioxide powder were put into a ball mill jar lined with zirconium oxide, and zirconium oxide grinding balls were added. The ball-to-material mass ratio was set to 20:1.

[0077] After sealing the ball mill jar, it is placed in a planetary ball mill for dry mechanical mixing. The rotation speed is set to 600 rpm and the continuous grinding time is 1 hour. After grinding, the material is collected to obtain micron-sized precursor uniformly mixed powder.

[0078] Preparation Example 4:

[0079] This preparation example provides a method for preparing a basic precursor mixture without heterogeneous metal doping and with niobium pentachloride accounting for 5% of the total niobium molar amount, including the following steps:

[0080] In a glove box with a dew point temperature below -40°C and filled with high-purity argon gas of not less than 99.999%, niobium pentachloride is accurately weighed, based on the total molar amount of niobium atoms in the system, such that it provides 5% of the total molar amount of niobium atoms in the system.

[0081] Accurately weigh niobium pentoxide to provide the remaining 95% of niobium atoms; accurately weigh anhydrous sodium chloride to make the molar ratio of sodium atoms to total niobium atoms 1:1.

[0082] In this preparation example, no heterogeneous metal doping source was added. The weighed anhydrous sodium chloride, niobium pentoxide, and niobium pentachloride powder were put into a ball mill jar lined with zirconium oxide, and zirconium oxide grinding balls were added. The ball-to-material mass ratio was set to 15:1.

[0083] After sealing the ball mill jar, it is placed in a planetary ball mill for dry mechanical mixing. The rotation speed is set to 400 rpm and the continuous grinding time is 2 hours. After grinding, the material is collected to obtain micron-sized precursor uniformly mixed powder.

[0084] Example 1:

[0085] This embodiment provides a solid electrolyte with high ionic conductivity and its preparation method, including the following steps:

[0086] Take the uniformly mixed precursor powder obtained in Preparation Example 1 and load it into a closed continuous tubular reactor lined with corrosion-resistant silicon carbide material.

[0087] The reactor was sealed and connected to a back pressure control valve. The system's safe exhaust absolute pressure threshold was set to 0.15 MPa.

[0088] The reactor was heated to 225°C at a heating rate of 3.0°C / min, and then held at this temperature and pressure for 3 hours to maintain the absolute pressure inside the reactor in a slightly positive state.

[0089] After the medium-temperature constant-pressure holding period, without compromising the reactor's airtightness and back pressure setting, the heating program was adjusted to continue heating the reactor temperature from 225℃ to the main reaction temperature of 600℃ at a low heating rate of 1.5℃ / min, and then holding at 600℃ for 8 hours.

[0090] After the main reaction is kept warm, the power supply to the main heating furnace is disconnected, and the powder material at 600°C is directly transferred to the closed fluidized cooling chamber located at the rear of the furnace body through a mechanical feeding device.

[0091] High-purity nitrogen gas at 0°C is simultaneously blown into the bottom of the cooling chamber, and the apparent flow rate of the gas is set to 2.0 times the critical fluidization velocity of the material, so that the high-temperature powder is in a gas-solid fluidized state.

[0092] The temperature of the powder material is controlled to drop from 600°C to below 50°C within 10 minutes, and the cooled solid powder is collected to obtain the solid electrolyte.

[0093] Example 2:

[0094] This embodiment provides a solid electrolyte with high ionic conductivity and its preparation method, including the following steps:

[0095] Take the uniformly mixed precursor powder obtained in Preparation Example 2 and load it into a closed continuous tubular reactor lined with corrosion-resistant corundum material.

[0096] The reactor was sealed and connected to a back pressure control valve. The system's safe exhaust absolute pressure threshold was set to 0.12 MPa.

[0097] The reactor was heated to 200℃ at a heating rate of 2.0℃ / min, and then held at this temperature and pressure for 4 hours to maintain the absolute pressure inside the reactor in a slightly positive state.

[0098] After the medium-temperature constant-pressure holding is completed, without damaging the reactor's airtightness and back pressure setting, the heating program is adjusted to continue heating the reactor temperature from 200℃ to the main reaction temperature of 500℃ at a low heating rate of 1.0℃ / min, and then holding at 500℃ for 12 hours.

[0099] After the main reaction is kept warm, the power supply to the main heating furnace is disconnected, and the powder material at 500°C is directly transferred to the closed fluidized cooling chamber located at the rear of the furnace body by a mechanical feeding device.

[0100] High-purity nitrogen gas at a temperature of -20℃ is simultaneously blown into the bottom of the cooling chamber, and the apparent flow rate of the gas is set to 1.5 times the critical fluidization velocity of the material, so that the high-temperature powder is in a gas-solid fluidized state.

[0101] The temperature of the powder material is controlled to drop from 500°C to below 50°C within 10 minutes, and the cooled solid powder is collected to obtain the solid electrolyte.

[0102] Example 3:

[0103] This embodiment provides a solid electrolyte with high ionic conductivity and its preparation method, including the following steps:

[0104] Take the uniformly mixed precursor powder obtained in Preparation Example 3 and load it into a closed continuous tubular reactor lined with corrosion-resistant silicon carbide material.

[0105] The reactor was sealed and connected to a back pressure control valve. The system's safe exhaust absolute pressure threshold was set to 0.20 MPa.

[0106] The reactor was heated to 250°C at a heating rate of 5.0°C / min, and then held at this temperature and pressure for 2 hours to maintain the absolute pressure inside the reactor in a slightly positive state.

[0107] After the medium-temperature constant-pressure holding period, without compromising the reactor's airtightness and back pressure setting, the heating program was adjusted to continue heating the reactor temperature from 250℃ to the main reaction temperature of 700℃ at a low heating rate of 2.0℃ / min, and then holding at 700℃ for 6 hours.

[0108] After the main reaction is kept at a constant temperature, the power supply to the main heating furnace is disconnected, and the powder material at 700°C is directly transferred to the closed fluidized cooling chamber located at the rear of the furnace body through a pneumatic conveying device.

[0109] High-purity nitrogen gas at 20°C is simultaneously blown into the bottom of the cooling chamber, and the apparent flow rate of the gas is set to 3.0 times the critical fluidization velocity of the material, so that the high-temperature powder is in a gas-solid fluidized state.

[0110] The temperature of the powder material is controlled to drop from 700°C to below 50°C within 10 minutes, and the cooled solid powder is collected to obtain the solid electrolyte.

[0111] Example 4:

[0112] This embodiment provides a solid electrolyte with high ionic conductivity and its preparation method, including the following steps:

[0113] Take the uniformly mixed precursor powder obtained in Preparation Example 1 and load it into a closed continuous tubular reactor lined with corrosion-resistant silicon carbide material.

[0114] The reactor was sealed and connected to a back pressure control valve. The system's safe exhaust absolute pressure threshold was set to 0.15 MPa.

[0115] The reactor was heated to 225°C at a heating rate of 3.0°C / min, and then held at this temperature and pressure for 3 hours to maintain the absolute pressure inside the reactor in a slightly positive state.

[0116] After the medium-temperature constant-pressure holding period, without compromising the reactor's airtightness and back pressure setting, the heating program was adjusted to raise the reactor temperature from 225℃ to the main reaction temperature of 600℃ at a heating rate of 2.0℃ / min, and then held at 600℃ for 8 hours.

[0117] After the main reaction is kept warm, the power supply to the main heating furnace is disconnected, and the powder material at 600°C is directly transferred to the closed fluidized cooling chamber located at the rear of the furnace body through a mechanical feeding device.

[0118] High-purity nitrogen gas at 0°C is simultaneously blown into the bottom of the cooling chamber, and the apparent flow rate of the gas is set to 2.0 times the critical fluidization velocity of the material, so that the high-temperature powder is in a gas-solid fluidized state.

[0119] The temperature of the powder material is controlled to drop from 600°C to below 50°C within 10 minutes, and the cooled solid powder is collected to obtain the solid electrolyte.

[0120] Comparative Example 1:

[0121] Compared with Example 1, the difference is that niobium pentachloride is not added to the precursor mixture used. Instead, anhydrous sodium chloride, niobium pentoxide and tungsten trioxide are directly mixed for grinding and subsequent processes. All other aspects are the same.

[0122] Comparative Example 2:

[0123] Compared with Example 1, the difference is that the intermediate temperature constant temperature and pressure holding stage is cancelled. That is, after the system is sealed and pressurized, it directly rises from room temperature to 600°C at a heating rate of 1.5°C / min and is held at that temperature for 8 hours. All other aspects are the same.

[0124] Comparative Example 3:

[0125] Compared with Example 1, the difference is that after the medium-temperature constant temperature and pressure holding is completed, the low heating rate is cancelled and replaced with a rapid heating rate of 10.0℃ / min to heat the reactor temperature from 225℃ to 600℃. All other aspects are the same.

[0126] Comparative Example 4:

[0127] Compared with Example 1, the difference is that after the main reaction is kept at a constant temperature, the gas-solid fluidization metastable phase freezing stage is cancelled, and instead the power supply is not cut off, and conventional slow natural cooling to room temperature is adopted. All other aspects are the same.

[0128] Comparative Example 5:

[0129] Compared with Example 1, the difference is that the precursor homogeneous mixture without heterogeneous metal doping obtained in Preparation Example 4 is used, and the process of medium-temperature holding pressure, rapid heating at 10.0℃ / min and natural cooling with furnace is eliminated, while the rest are the same.

[0130] Test Example 1:

[0131] Weigh 0.100g of each of the solid electrolyte powders prepared in Examples 1 to 4.

[0132] The powder was placed in a polytetrafluoroethylene digestion vessel, and a mixture of 9 mL concentrated nitric acid and 3 mL hydrofluoric acid was added. After sealing the digestion vessel, it was placed in a microwave digester and digested at 200°C for 45 min.

[0133] After the solution has cooled and become clear, transfer it to a 100 mL volumetric flask and dilute to the final volume.

[0134] The mass concentrations of Na, Nb, W, and Ta in the solution were determined using inductively coupled plasma atomic emission spectrometry (ICP-AES), and the actual molar percentages of each transition metal element in the solid product were calculated.

[0135] Equal masses of powder were weighed and extracted using an ultrasonic method with a sodium carbonate-sodium bicarbonate mixed solution. After centrifugation, the supernatant was collected and the chloride ion content was determined by ion chromatography to calculate the chloride retention rate.

[0136] The powder samples from Examples 1 to 4 were ground in an agate mortar and passed through a 200-mesh sieve. The ground powder was then spread and fixed on the sample stage of an X-ray diffractometer.

[0137] A CuKα radiation source was used, and scanning tests were conducted under tube voltage of 40 kV and tube current of 40 mA. The scanning range was set to 10–80°, the scanning step size was set to 0.02°, and the scanning rate was [missing information]. .

[0138] After obtaining the X-ray diffraction patterns, the data were imported into GSAS software for Rietveld refinement, and the unit cell volume parameters of each sample were extracted.

[0139] Table 1. Elemental composition and crystallographic parameter test results for each group of samples.

[0140] Sample number Theoretical doped metal types ICP-OES determination of the molar percentage of doped metals (%) Chlorine retention rate determined by IC assay (%) XRD-refined unit cell volume (ų) Position of the main diffraction peak at 2θ (°) Example 1 W 2.87 98.4 185.712 26.43 Example 2 Ta 0.94 99.2 184.283 26.31 Example 3 W 4.91 97.6 186.204 26.62 Example 4 W 2.92 98.1 185.638 26.46

[0141] According to the data in Table 1, the ICP-OES results show that the actual molar percentages of tungsten in Examples 1, 3, and 4 are 2.87%, 4.91%, and 2.92%, respectively, while the actual percentage of tantalum in Example 2 is 0.94%. The percentages of metal elements in each sample are close to the theoretical addition amounts.

[0142] Meanwhile, the chlorine retention rate measured by IC fluctuated between 97.6% and 99.2%.

[0143] This indicates that in the designed closed back pressure control reactor, the system controlled the vaporization loss of low-boiling-point components and maintained the initial design ratio of oxygen and chlorine within the material system.

[0144] Refined data from X-ray diffraction tests show that the cell parameters of the product shifted systematically with increasing heteroelement doping concentration.

[0145] The cell volume of Example 1 was 185.712 ų. When the tungsten doping amount was increased to close to 5% (Example 3), the cell volume shrank to 184.804 ų, and the position of the main diffraction peak shifted from 26.43° to 26.62°.

[0146] This change in lattice parameters confirms that tungsten and tantalum elements have entered the lattice sites of the main niobium-oxygen framework.

[0147] Based on the preparation mechanism of this invention, the gaseous medium generated by the vaporization of niobium pentachloride serves as a transport carrier, enabling high-valence ions that are difficult to diffuse in the solid phase to disperse into the basic crystal lattice.

[0148] The successful solid solution and temperature-controlled process of the elements promoted the disordered arrangement of oxygen and chloride ions in the system.

[0149] Test Example 2:

[0150] In a glove box filled with high-purity argon, 150.0 mg of each of the solid powders prepared in Examples 1 to 4 and Comparative Examples 1 to 5 were weighed.

[0151] The powder was placed in a polytetrafluoroethylene mold with an inner diameter of 10.0 mm and pressed into a dense ceramic sheet by pressing it under a pressure of 350 MPa for 3 minutes using a powder tablet press.

[0152] The actual thickness and diameter of each ceramic sheet were measured using vernier calipers. The ceramic sheets were then transferred into the vacuum chamber of an ion sputtering instrument, and gold films with a thickness of approximately 50 nm were sputtered on the upper and lower end faces of the ceramic sheets as blocking electrodes.

[0153] The ceramic plates with gold electrodes on both sides are assembled into the CR2032 button battery casing and mechanically sealed.

[0154] Connect the packaged button cell to the electrochemical workstation.

[0155] The test system was placed in a constant temperature bath at 25.0℃ and allowed to stand for 2 hours to allow the battery to reach thermal equilibrium. The battery impedance was tested using AC impedance spectroscopy, with the AC voltage perturbation amplitude set to 10mV and the scanning frequency range set to 1MHz to 0.1Hz.

[0156] To clearly compare the impedance characteristics of different samples, a semicircular fitting was performed on the acquired raw test data using an equivalent circuit. The fitted AC impedance spectrum curve is shown below. Figure 3 As shown.

[0157] Based on the fitted curves, it can be seen that the right intercept of the semicircle in the high-frequency to mid-frequency region on the real axis corresponds to the total impedance of the system. Thus, the bulk impedance and grain boundary impedance values ​​of the solid electrolyte can be extracted.

[0158] The initial room temperature total ionic conductivity was calculated by combining the cross-sectional area and thickness of the test sample.

[0159] Take another batch of solid electrolyte ceramic sheets that were pressed according to the method in step 1 but without sputtering gold electrodes, and place them in a constant temperature and humidity test chamber with an ambient temperature of 25.0℃ and a relative humidity of 35%.

[0160] The sample was removed after being continuously exposed to a set air environment for 72 hours, and the surface was wiped with lint-free paper.

[0161] Following the procedure in step 1, gold electrodes were sputtered onto both ends of the sample and then encapsulated into a button cell casing.

[0162] Perform the AC impedance test again using the parameters from step 2, calculate the total ionic conductivity after exposure to air, and compare it with the initial conductivity to calculate the retention rate.

[0163] Table 2 shows the impedance, conductivity, and air exposure stability test data for each group of solid electrolyte samples.

[0164] Sample number Initial total impedance (Ω) Initial room temperature total conductivity (mS / cm) Total impedance (Ω) after 72 hours of exposure Total conductivity after exposure (mS / cm) Conductivity retention rate (%) Example 1 66.9 1.56 72.5 1.44 92.3 Example 2 76.8 1.31 82.3 1.22 93.1 Example 3 62.2 1.64 69.1 1.48 90.2 Example 4 107.6 0.98 125.7 0.84 85.7 Comparative Example 1 278.3 0.36 824.6 0.12 33.3 Comparative Example 2 332.4 0.31 1145.2 0.09 29.0 Comparative Example 3 224.0 0.45 608.5 0.16 35.5 Comparative Example 4 690.9 0.15 1856.3 0.05 33.3 Comparative Example 5 1166.9 0.07 3584.1 0.02 28.5

[0165] According to the data in Table 2, the initial room temperature total ionic conductivity of Examples 1, 2 and 3 ranged from 1.31 to 1.64 mS / cm.

[0166] Comparative Example 5 uses an undoped precursor without process optimization, and its conductivity is only 0.07 mS / cm. The embodiment scheme improves the conductivity of niobium-based oxyhalides by more than an order of magnitude through tungsten or tantalum doping combined with in-situ chemical vapor transport and temperature-controlled freezing processes, breaking through the room temperature conductivity bottleneck and replacing high-cost zirconium and hafnium substrates.

[0167] A comparison of the data from Examples 1 to 3 with those from Comparative Examples 1 and 2 shows that Comparative Example 1 did not add niobium pentachloride, and Comparative Example 2 omitted the intermediate temperature and pressure holding stage.

[0168] The initial conductivity of these two comparisons decreased to 0.36 mS / cm and 0.31 mS / cm, respectively, and the grain boundary impedance increased significantly.

[0169] The solid-phase diffusion of refractory metal elements is limited due to the lack of a gas-phase transport medium formed by the sublimation of niobium pentachloride or the lack of relaxation time for gas-solid interface reactions.

[0170] The uneven distribution of heterogeneous elements in the niobium-oxygen framework induces phase segregation, which blocks the ion transition channels across grain boundaries.

[0171] The introduction of vapor-phase flux is a necessary condition for achieving homogeneous distribution of doping elements.

[0172] The comparison between Example 1, Example 4, and Comparative Example 3 reflects the effect of heating rate on lattice disorder.

[0173] Example 4 increased the heating rate of the main reaction, reducing the conductivity to 0.98 mS / cm; Comparative Example 3 eliminated the low heating rate stage, further reducing the conductivity to 0.45 mS / cm. Rapid heating deprived oxygen and chloride ions of the relaxation time required to overcome their thermodynamic separation tendency, resulting in insufficient statistical random occupancy of anions at polyhedral sites.

[0174] Some lattice channels are blocked by locally ordered aggregates of chloride or oxygen ions. Slow heating is a key kinetic condition for driving the disordered assembly of anions and widening the three-dimensional transport channels.

[0175] The comparison between Example 1 and Comparative Example 4 confirms the necessity of gas-solid fluidized bed quenching. Comparative Example 4 used natural cooling with the furnace, and its initial conductivity dropped to 0.15 mS / cm.

[0176] The slow cooling process causes the disordered oxygen-chlorine distribution formed at high temperature to undergo a dephase transition, the system energy evolves towards the equilibrium state, the crystal lattice rearranges, and a large number of cation vacancies and defect channels close.

[0177] The rapid cooling with a large temperature difference within 10 minutes of fluidization cut off the diffusion path of atoms, forcibly freezing the metastable phase with high electrical conductivity to room temperature.

[0178] Regarding air stability, after 72 hours of exposure to air at 35% relative humidity, the conductivity of Examples 1, 2, and 3 remained between 1.22 and 1.48 mS / cm, with a retention rate of over 90%. In contrast, the conductivity of the comparative samples generally decreased by more than 60% after exposure.

[0179] The disordered oxyhalide coupled defect state lattice prepared in the examples constructs a continuous conduction network on a macroscopic scale, and its unique microscopic electron cloud distribution structure forms a chemical passivation layer on the material surface.

[0180] Water molecules have difficulty penetrating the crystal lattice to disrupt the coordination environment of sodium ions, thus ensuring the structural and conductive stability of the material in normal ambient air.

[0181] Test Example 3:

[0182] In a glove box filled with high-purity argon, solid electrolyte powders prepared in each example and comparative example were pressed into dense ceramic sheets with a thickness of about 0.8 mm using a powder press at a pressure of 350 MPa.

[0183] A sodium foil with a diameter of 8.0 mm is attached to one side of the ceramic plate as the counter electrode and reference electrode, and a stainless steel foil is covered on the other side as the working electrode.

[0184] The above-mentioned stacked structure is inserted into a CR2032 button battery casing and sealed to produce an asymmetric battery.

[0185] The asymmetric battery was connected to the electrochemical workstation and left to stand for 4 hours in a constant temperature environment of 25.0℃.

[0186] The electrochemical stability window of the solid electrolyte was tested using a linear sweep voltammetry method, with a scan rate of 0.1 mV / s and a voltage scan range from the initial open-circuit voltage to 6.0 V.

[0187] Record the current versus voltage curve, and extract the inflection point voltage at which the anode current experiences a sustained jump and the response value exceeds 10 μA, as the oxidative decomposition potential of the material.

[0188] Take another solid electrolyte ceramic sheet from the same batch and symmetrically attach 8.0 mm diameter sodium foil to both its upper and lower end faces.

[0189] A longitudinal pressure of 15 MPa is applied within the assembly mold to physically bond sodium metal to the ceramic sheet, and then the sodium symmetric battery is encapsulated.

[0190] The symmetrical battery was connected to a battery charge-discharge tester and subjected to constant current cycling tests at 25.0℃. A fixed current density of 0.1 mA / cm² was set during the test, and the surface capacity of a single charge-discharge cycle was limited to 0.1 mAh / cm².

[0191] Record the curve of polarization voltage change over time until the voltage drops irreversibly, and extract the corresponding time as the stable cycle duration.

[0192] Take another set of sodium symmetric cells assembled using the same method as in step 3 and perform critical current density tests.

[0193] The initial current density was set at 0.05 mA / cm², and then the current density was increased by 0.05 mA / cm² every 2 hours for charging and discharging. The maximum tolerable current density before the system experienced an internal short circuit was recorded.

[0194] Table 3. Electrochemical windows and sodium-symmetric cell cycle test data for each group of solid electrolyte samples.

[0195] Sample number Oxidative decomposition potential Critical current density (mA / cm²) Stable cycle duration (h) Example 1 4.23 0.65 642 Example 2 4.18 0.58 615 Example 3 4.27 0.62 688 Example 4 4.05 0.42 312 Comparative Example 1 3.76 0.15 85 Comparative Example 3 3.82 0.18 114 Comparative Example 4 3.88 0.22 156

[0196] According to the data in Table 3, the oxidation decomposition potentials of Examples 1 to 3 ranged from 4.18V to 4.27V, the stable cycle time exceeded 600h, and the critical current density reached more than 0.58mA / cm².

[0197] Comparative Example 1, without the addition of niobium pentachloride gaseous medium and without the doping of heterogeneous elements, has an oxidation potential of only 3.76V, and the symmetric cell experienced an internal short circuit after 85 hours of operation.

[0198] Comparative data demonstrates that the incorporation of high-valence transition metals such as tungsten or tantalum modulates the Fermi level of the niobium-based oxyhalide framework, reducing high-voltage instability caused by the oxidation and precipitation of halide anions. Gas-phase medium-assisted homogeneous doping eliminates the aggregation of localized defects within the material, thereby improving the overall high-voltage electrochemical stability window of the material.

[0199] The test results of Examples 1 and 4, and Comparative Example 3 show that changing the temperature control heating rate has a direct impact on the physicochemical stability of the interface.

[0200] In Example 4 and Comparative Example 3, due to the use of a faster heating regime, the degree of disorder of anions was insufficient, and the resulting ion transport channels exhibited anisotropy.

[0201] During constant current charge and discharge, the uneven distribution of sodium ions within the solid phase and at the electrode / electrolyte interface leads to local current density overload, which accelerates the nucleation and growth of sodium metal dendrites, resulting in a reduction in cycle life to 312h and 114h, respectively.

[0202] The slow heating mechanism facilitated the full disordered occupancy of oxygen and chlorine atoms, constructing an isotropic three-dimensional ion transport network, thus avoiding the space charge layer polarization of sodium ions at the interface from a kinetic perspective.

[0203] The comparison between Example 1 and Comparative Example 4 verifies the role of the fluidized bed cooling process in the interface compatibility of solid-state batteries. In Comparative Example 4, furnace cooling caused the high-temperature phase to transform into the low-temperature steady-state phase, resulting in a decrease in lattice vacancy concentration, a decrease in overall conductivity, and an increase in interfacial charge transfer impedance.

[0204] The slow kinetic process at the interface induced uneven deposition and stripping of sodium metal, and its critical current density dropped to 0.22 mA / cm².

[0205] The metastable disorder defect structure obtained by rapid freezing has a high concentration of ion transition sites, ensuring a sufficient sodium ion supply rate at the interface and maintaining the mechanical integrity and electrochemical stability of the interface during long-term cycling.

[0206] The solution of this invention extends from the optimization of bulk structure to the improvement of electrode interface behavior, thus meeting the actual operating requirements of high-energy-density sodium metal solid-state batteries.

[0207] Test Example 4:

[0208] In a glove box filled with high-purity argon, commercial sodium vanadium phosphate powder, SuperP conductive carbon black, and solid electrolyte powder prepared in each example and comparative example were weighed and mixed at a mass ratio of 65:10:25.

[0209] The mixture was placed in an agate mortar and ground for 45 minutes to ensure that the electrolyte powder was evenly coated on the surface of the active material particles.

[0210] Add 5% polytetrafluoroethylene as a binder and add an appropriate amount of anhydrous ethanol for mixing.

[0211] The kneaded agglomerates are repeatedly rolled on a roller press to produce a composite positive electrode sheet with a thickness of about 60 μm.

[0212] The electrode was punched into a circular sheet with a diameter of 10.0 mm using a slicing machine and then dried in a vacuum drying oven at 110°C for 12 hours.

[0213] Each set of solid electrolyte ceramic sheets, pressed and molded, serves as a separator layer. The composite positive electrode disc prepared above is attached to one side of the solid electrolyte sheet, and a sodium metal foil with a diameter of 12.0 mm is attached to the other side.

[0214] The three-layer structure is placed in the CR2032 button cell casing, and after adding wave spring sheets and gaskets, it is mechanically pressed and sealed to assemble an all-solid-state sodium metal battery.

[0215] The assembled all-solid-state battery is then connected to the Newwell battery testing system.

[0216] The test environment was maintained at 25.0℃ in a constant temperature bath. The charge / discharge voltage range was set from 2.5V to 3.8V. Activation was performed for three cycles at a current density of 0.1C, and the initial coulombic efficiency and 0.1C reversible specific capacity were recorded.

[0217] Subsequently, five cycles were performed at current densities of 0.2C, 0.5C, and 1.0C respectively to test the rate performance of the full cell and extract the discharge specific capacity at 1.0C.

[0218] After the rate test, the charge / discharge current density was restored to 0.5C, and 200 constant current charge / discharge cycles were performed continuously.

[0219] The system automatically records the discharge capacity of each cycle, and calculates the capacity retention rate of the discharge capacity of the 200th cycle relative to the first cycle after the cycle is completed.

[0220] Table 4. Test data of charge-discharge and cycle performance of all-solid-state batteries for each group of solid electrolyte samples.

[0221] Sample number First-time coulomb efficiency (%) 0.1C discharge specific capacity (mAh / g) 1.0C discharge specific capacity (mAh / g) Capacity retention rate (%) after 200 cycles at 0.5C Example 1 91.4 104.6 92.1 88.5 Example 2 92.8 101.3 87.6 86.2 Example 3 89.5 106.8 94.4 89.3 Example 4 85.2 96.1 71.8 68.4 Comparative Example 1 68.4 74.5 18.2 41.6 Comparative Example 3 77.1 82.3 36.5 52.8 Comparative Example 4 64.6 69.8 12.7 35.2

[0222] According to the data in Table 4, the full cells assembled in Examples 1 to 3 achieved a discharge specific capacity of 101.3 mAh / g to 106.8 mAh / g at 0.1C, and the initial coulombic efficiency remained in the range of 89.5% to 92.8%.

[0223] When the current density is increased to 1.0C, the discharge specific capacity can still be maintained above 87.6mAh / g, and the capacity retention rate after 200 cycles at 0.5C is higher than 86%.

[0224] Comparative Example 1, which did not introduce niobium pentachloride gas-phase transport medium and heterogeneous doping elements, had a discharge specific capacity of only 74.5 mAh / g at 0.1C and a capacity decay to 18.2 mAh / g at 1.0C.

[0225] The data discrepancies confirm that the solid solution combination of tungsten or tantalum ions with a gas-phase flux mechanism constructs a continuous sodium ion transport channel within the electrolyte bulk phase. Inside the composite cathode, the charge transfer impedance at the interface between the modified electrolyte powder and the active material particles is reduced, ensuring rapid intercalation and deintercalation of sodium ions at the solid-solid interface at high rates, and preventing premature termination of discharge due to excessive polarization reaching the cutoff threshold.

[0226] Example 4 and Comparative Example 3 increased the heating rate in the early stage of the reaction, and the initial coulombic efficiency of the full cell decreased to 85.2% and 77.1%, respectively. The specific capacity at 1.0C high rate and the long cycle retention rate showed a significant decrease.

[0227] Rapid heating interfered with the statistically random distribution of chloride and oxygen ions at the vertices of the crystal lattice polyhedron.

[0228] The locally ordered micro-regions remaining within the structure exhibit conduction anisotropy in the complex stress environment of the composite cathode.

[0229] During cycling, the strain caused by the volume contraction and expansion of the positive electrode particles cannot be effectively relaxed by the intrinsic defects of the solid electrolyte, resulting in physical separation of the electrode-electrolyte interface. Some active materials lose their ion contact network and become dead zones, which macroscopically manifests as an irreversible loss of usable capacity.

[0230] Comparative Example 4 uses a natural cooling mechanism, and its full cell has an initial coulombic efficiency as low as 64.6%, with a capacity retention of only 35.2% after 200 cycles.

[0231] The slow cooling process released the lattice thermal stress accumulated during the high-temperature reaction stage, and the system degraded from a metastable state rich in vacancies and interstitial sodium ions to a thermodynamically stable state. The sharp reduction in vacancy concentration directly severed the three-dimensional percolation network inside the composite cathode.

[0232] During repeated charge-discharge cycles, low conductivity leads to severe concentration polarization, and the accumulation of sodium ions at the interface exacerbates the high-pressure decomposition side reactions of the electrolyte.

[0233] The fluidized bed quenching process forcibly preserves the high-entropy disorder characteristics and distorted lattice of the high-temperature phase, providing a buffer space to accommodate the reaction products at the electrode interface and maintaining the electrochemical impedance stability of the full cell under long-term operation.

[0234] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A solid electrolyte with high ionic conductivity, characterized in that, The solid electrolyte is prepared by reacting a precursor mixture. Based on the total molar amount of total metal atoms in the system, the precursor mixture comprises raw materials with the following composition: The heterometallic doping source provides heterometallic atoms accounting for 1% to 5% of the total molar amount of metal atoms; niobium pentachloride provides niobium atoms accounting for 2% to 8% of the total molar amount of niobium atoms in the system. Niobium pentoxide provides the remaining 92%–98% of the niobium atoms in the system; Anhydrous sodium chloride results in a molar ratio of sodium atoms to total metal atoms of 1:1; The niobium pentachloride acts as a gas-phase transport agent that provides self-generated pressure and chlorine source during the reaction, promoting the heterogeneous metal element to enter the lattice sites of the main niobium-oxygen framework and forming a metastable phase with high ionic conductivity and disordered anion distribution.

2. The solid electrolyte with high ionic conductivity according to claim 1, characterized in that, The heterogeneous metal doping source is tungsten trioxide or tantalum pentoxide; Preferably, when the heterometallic dopant source is tungsten trioxide, tungsten atoms account for 3% to 5% of the total molar amount of metal atoms, corresponding to niobium atoms provided by niobium pentachloride accounting for 5% to 8% of the total molar amount of niobium atoms in the system; When the heterometallic doping source is tantalum pentoxide, tantalum atoms account for 1% of the total molar amount of metal atoms, corresponding to niobium atoms provided by niobium pentachloride accounting for 2% of the total molar amount of niobium atoms in the system.

3. A solid electrolyte with high ionic conductivity according to claim 1, characterized in that, The method for preparing the precursor mixture includes: Anhydrous sodium chloride is pre-treated to remove surface adsorbed water. In a glove box filled with high-purity argon, weighed anhydrous sodium chloride, niobium pentoxide, niobium pentachloride, and heterogeneous metal dopant source powder are put into a ball mill jar for dry mechanical mixing. The ball-to-material mass ratio is set to 10:1 to 20:1, the rotation speed is set to 300 to 600 rpm, and the continuous grinding time is 1 to 3 hours to obtain micron-sized precursor uniformly mixed powder.

4. The solid electrolyte with high ionic conductivity according to claim 1, characterized in that, The chlorine retention rate in the solid electrolyte is 97.6%–99.2%; The initial room temperature total ionic conductivity of the solid electrolyte is 1.31–1.64 mS / cm.

5. A method for preparing a solid electrolyte with high ionic conductivity, comprising the solid electrolyte with high ionic conductivity according to any one of claims 1-4, characterized in that, Includes the following steps: S1. The precursor mixture as described in claim 1 is loaded into a closed continuous tubular reactor, the reactor is sealed and a back pressure control valve is connected, and the system’s safe exhaust absolute pressure threshold is set. S2. Heat the reactor to the medium temperature range at the first heating rate and maintain the constant temperature and pressure to keep the absolute pressure inside the reactor in a slightly positive state, thereby promoting the formation of the gas phase transport medium. S3. After the medium-temperature constant temperature and pressure holding is completed, without damaging the reactor's airtightness and back pressure setting, the reactor is heated to the main reaction temperature at the second heating rate and held at that temperature to drive the disordered assembly of anions and broaden the three-dimensional transport channels. S4. After the main reaction is kept at the temperature, the powder material at the main reaction temperature is transferred to a closed fluidized cooling chamber. Cooling gas is simultaneously blown into the bottom of the cooling chamber to make the powder in a gas-solid fluidized state. Metastable phase rapid freezing and condensation are carried out in a short time. The cooled solid powder is collected to obtain the solid electrolyte.

6. The method for preparing a solid electrolyte with high ionic conductivity according to claim 5, characterized in that, In step S1, the set absolute pressure threshold for safe exhaust is 0.12MPa to 0.20MPa; the closed continuous tubular reactor is lined with corrosion-resistant silicon carbide material or corrosion-resistant corundum material.

7. The method for preparing a solid electrolyte with high ionic conductivity according to claim 5, characterized in that, In step S2, the first heating rate is 2.0–5.0 °C / min, the intermediate temperature range is 200–250 °C, and the constant temperature and pressure holding time is 2–4 h.

8. The method for preparing a solid electrolyte with high ionic conductivity according to claim 5, characterized in that, In step S3, the second heating rate is lower than the first heating rate, the second heating rate is 1.0 to 2.0 °C / min, the main reaction temperature is 500 to 700 °C, and the holding time is 6 to 12 h.

9. The method for preparing a solid electrolyte with high ionic conductivity according to claim 5, characterized in that, The specific implementation method of step S4 is as follows: disconnect the power supply of the main heating furnace, and transfer the powder material directly to the closed fluidized cooling chamber located at the rear end of the furnace body through a mechanical pushing device or a pneumatic conveying device.

10. The method for preparing a solid electrolyte with high ionic conductivity according to claim 5, characterized in that, In step S4, the cooling gas is high-purity nitrogen gas with a temperature between -20℃ and 20℃. The apparent flow rate of the cooling gas is set to 1.5 to 3.0 times the critical fluidization rate of the material, and the temperature of the powder material is controlled to drop from the main reaction temperature to below 50℃ within 10 minutes.

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