NASICON-type solid electrolyte, cathode material coated with it, and preparation method

Abstract

This invention relates to a NASICON-type solid electrolyte, a cathode material coated thereon, and a method for preparing the same, specifically the Li... x M 1 y M 2 z M 3 u (PO4) w1 (RO v ) w2 The NASICON-type solid electrolyte and its preparation method are disclosed, wherein the cell volume of the NASICON-type solid electrolyte calculated based on XRD test data is approximately equal to the standard value of 1.31031 nm. 3 The difference is greater than 0.01nm 3 The present invention also relates to a positive electrode material coated with the aforementioned NASICON-type solid electrolyte and a method for preparing the same.

Description

Technical Field

[0001] This invention relates to NASICON-type solid electrolytes and their preparation methods, as well as positive electrode materials coated with the NASICON-type solid electrolytes and their preparation methods. Background Technology

[0002] The rapid development of the power battery and energy storage battery market has prompted higher demands for the energy density and safety performance of lithium-ion batteries. Traditional lithium-ion batteries, due to the use of electrolytes in their structure, have significant safety risks and are limited to using lithium-free negative electrodes, thus the potential for increasing battery energy density has reached a bottleneck. Solid-state batteries, by using solid electrolytes instead of traditional electrolytes, can fundamentally solve battery safety issues. Furthermore, by using lithium-containing negative electrodes instead of traditional graphite or silicon-carbon negative electrodes, they can further improve battery energy density and have become the recognized next-generation lithium battery development direction.

[0003] In solid-state battery systems, one of the most critical materials is the solid electrolyte. Solid electrolytes include organic polymers, sulfides, halides, perovskites, nASICON, and garnets, among others. NASICON-type solid electrolytes, in particular, possess advantages such as high conductivity, good thermal stability, and a wide electrochemical window, making them one of the most promising solid electrolytes for industrialization.

[0004] NASICON-type solid electrolytes can achieve a theoretical ionic conductivity of up to 10. -3 The S / cm ratio is above 0.5, but current research reports generally show values ​​below 0.5 × 10⁻⁶. -3 The ionic conductivity is only S / cm, so there is still considerable room for improvement. NASICON-type solid electrolytes, after nano-sizing, suffer from structural instability and easy phase separation, which is detrimental to the long-term preservation of nano-slurries. Furthermore, to effectively improve their ionic conductivity, researchers have primarily utilized wet chemical reaction methods such as hydrothermal and sol-gel methods for performance enhancement, which are not feasible for low-cost, large-scale production. Traditional solid-phase reactions are prone to the formation of impurity phases due to uneven mixing of raw materials.

[0005] On the other hand, for mainstream multi-element cathode materials, while energy density gradually increases with increasing nickel content, thermal stability gradually decreases, severely affecting battery safety. Some studies have attempted to improve safety by coating multi-element cathode materials with structurally stable cathode materials such as lithium iron phosphate. However, lithium iron phosphate has a one-dimensional lithium-ion transport channel and poor conductivity, so coating it with multi-element cathode materials results in a deterioration in the overall capacity and rate performance of the material. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a multi-site doped NASICON-structured solid electrolyte prepared by gel casting and its preparation method. The NASICON-structured solid electrolyte provided by this invention is prepared using a gel casting method, which features simple operation, high controllability, and ease of mass production. During the gel formation process, dopant elements are introduced to achieve atomic-level uniform mixing between the elements and the main phase. The prepared solid electrolyte exhibits uniform composition, high ionic conductivity, and an average particle size reaching the nanometer scale. The presence of dopant elements within the crystal lattice contributes to its excellent structural stability, allowing the nanoscale slurry to maintain a pure phase state for extended periods without phase decomposition. The prepared nanoscale solid electrolyte slurry and powder possess a high specific surface area and strong specific surface energy, making it suitable for the preparation of composite solid electrodes and ceramic-coated separators.

[0007] The nanoscale NASICON-structured solid electrolyte prepared using the above method can effectively improve the thermal stability of multi-element cathode materials by surface coating, and also enhances their electrochemical performance, such as capacity, rate capability, and cycle life. Acid-base titration of the coated ternary material reveals distinct characteristic titration peaks.

[0008] On the one hand, the present invention provides a NASICON-type solid electrolyte conforming to the following formula,

[0009] Li x M 1 y M 2 z M 3 u (PO4) w1 (RO v ) w2

[0010] in,

[0011] M 1 It is at least one element selected from Mg, Na, and K.

[0012] M 2 It is at least one element selected from Al, Ga, In, Y, and Sc.

[0013] M 3 It is at least one element selected from Ti, Zr, and Ge.

[0014] R is at least one element selected from Si, Cl, Br, S, Sb, and Sn.

[0015] 0≤x<5, 0≤y≤0.5, 0≤z≤1, 0≤u≤9,

[0016] The conditions are: 1≤v≤3, 1≤w1≤3, 0≤w2≤3, and the total charge of the anions is 9.

[0017] The cell volume of the NASICON-type solid electrolyte, calculated based on XRD test data, is approximately 1.31031 nm, consistent with the standard value. 3 The difference is greater than 0.01nm 3 .

[0018] On the other hand, the present invention also provides a method I for preparing a NASICON-type solid electrolyte according to the present invention, which includes the following steps:

[0019] (1-1) The raw material compound of NASICON type solid electrolyte is mixed with organic monomer and solvent, crushed to obtain mixture A, and then an initiator and catalyst are added to obtain mixture B;

[0020] (1-2) The mixture B is poured into a container and heated to initiate a polymerization reaction to obtain a bulk solid electrolyte precursor A;

[0021] (1-3) The solid electrolyte precursor A is pre-sintered and then crushed to obtain powdered solid electrolyte precursor B;

[0022] (1-4) The solid electrolyte precursor B is sintered and then crushed to obtain powdered, micron-sized solid electrolyte A; and

[0023] (1-5) The solid electrolyte A is ground to obtain a slurry with nano-sized particles, and then dried to obtain a powdery, nano-sized NASICON-type solid electrolyte.

[0024] On the other hand, the present invention also provides a coated positive electrode material, wherein the matrix of the positive electrode material is coated with a NASICON-type solid electrolyte according to the present invention.

[0025] On the other hand, the present invention also provides a method II for preparing the coated cathode material according to the present invention, comprising the following steps:

[0026] (2-1) The NASICON-type solid electrolyte is mixed with the matrix of the positive electrode material, and (2-2) the coated positive electrode material is obtained by heat treatment. Attached Figure Description

[0027] Figure 1 The XRD pattern of the products shown is that of the comparative example and the embodiment.

[0028] Figure 2 The XRD pattern shown is that of the products in the comparative and example embodiments after abuse testing; and

[0029] Figure 3 The titration curve of the product in Example 4 is shown. Detailed Implementation

[0030] Unless otherwise stated, the entire contents of all publications, patent applications, patents and other references mentioned herein are expressly incorporated herein by reference for all purposes, as fully illustrated.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification, including the definitions, shall prevail.

[0032] If a quantity, concentration, or other numerical value or parameter is given as a range, a preferred range, or a series of preferred upper and lower limits, it should be understood that all ranges formed by any pair of any upper or preferred numerical values ​​and any lower or preferred numerical values ​​are specifically disclosed, regardless of whether these ranges are disclosed separately. When referring to ranges of numerical values ​​herein, unless otherwise stated, it means that the range includes its endpoints and all integers and fractions within that range.

[0033] On one hand, the present invention relates to a NASICON-type solid electrolyte conforming to the following formula:

[0034] Li x M 1 y M 2 z M 3 u (PO4) w1 (RO v ) w2

[0035] in,

[0036] M 1 It is at least one element selected from Mg, Na, and K.

[0037] M 2 It is at least one element selected from Al, Ga, In, Y, and Sc.

[0038] M 3 It is at least one element selected from Ti, Zr, and Ge.

[0039] R is at least one element selected from Si, Cl, Br, S, Sb, and Sn.

[0040] The following conditions must be met: 0≤x<5, preferably 0.6≤x<3.2, more preferably 1.0≤x<2.0; 0≤y≤0.5, preferably 0≤y≤0.3, more preferably 0≤y≤0.1, particularly preferably 0.05; 0≤z≤1, preferably 0.2≤z≤0.7, more preferably 0.2≤z≤0.4, particularly preferably 0.3; 0≤u≤9, preferably 0.9≤u≤5.4, more preferably 1.4≤u≤3.2, particularly preferably 1.7; 1≤v≤3, 1≤w1≤3, 0≤w2≤3, provided that the total charge of the anions is 9.

[0041] The cell volume of the NASICON-type solid electrolyte, calculated based on XRD test data, is approximately 1.31031 nm, consistent with the standard value. 3 The difference is greater than 0.01nm 3 .

[0042] The multi-site doped NASICON structure solid electrolyte exhibits variations in its unit cell parameters due to uniform elemental doping at different sites. Specifically, the unit cell volume calculated from XRD test data differs from the standard value (1.31031 nm). 3 The difference is greater than 0.01 nm. 3 Furthermore, by examining the atomic arrangement of the sample using high-resolution transmission microscopy, relatively obvious point defects can be found at the corresponding positions of Li, M, and P.

[0043] According to one embodiment of the NASICON-type solid electrolyte of the present invention, the average particle size D of the NASICON-type solid electrolyte is... 50 The specific surface area is 0.01 to 5 μm, preferably 0.05 to 1 μm, and more preferably 0.1 to 0.5 μm. The NASICON-type solid electrolyte has a specific surface area >10 m². 2 / g. The pH of the NASICON-type solid electrolyte is >5. The ionic conductivity of the NASICON-type solid electrolyte is >10. -4 S / cm. The electronic conductivity of the NASICON-type solid electrolyte is >10. -10 S / cm. The nanoscale slurry of the solid electrolyte does not exhibit precipitation or phase decomposition after prolonged standing.

[0044] On the other hand, the present invention also relates to a method I for preparing a NASICON-type solid electrolyte according to the present invention, which includes the following steps:

[0045] (1-1) The raw material compound of NASICON type solid electrolyte is mixed with organic monomer and solvent, crushed to obtain mixture A, and then an initiator and catalyst are added to obtain mixture B;

[0046] (1-2) The mixture B is poured into a container and heated to initiate a polymerization reaction to obtain a bulk solid electrolyte precursor A;

[0047] (1-3) The solid electrolyte precursor A is pre-sintered and then crushed to obtain powdered solid electrolyte precursor B;

[0048] (1-4) The solid electrolyte precursor B is sintered and then crushed to obtain powdered, micron-sized solid electrolyte A; and

[0049] (1-5) The solid electrolyte A is ground to obtain a slurry with nano-sized particles, and then dried to obtain a powdery, nano-sized NASICON-type solid electrolyte.

[0050] The method for preparing NASICON-type solid electrolyte provided by this invention is gel casting. Compared with the sol-gel method, the gel casting method uses less solvent and chelating agent, and has a higher solid content. The added organic monomers undergo polymerization reaction, which can make the raw material elements of NASICON material uniformly combined at the molecular level. After sintering, the polymer is oxidized and volatilized, and the raw materials react to form a uniform NASICON phase.

[0051] According to Method I of the present invention, the element doping is made more uniform by introducing doping elements during the thermal polymerization process. Furthermore, different degrees of element doping are present at different locations in the solid electrolyte, including Li, P, and transition metals.

[0052] According to one embodiment of method I of the present invention, in step (1-1), the raw material compound of the NASICON-type solid electrolyte is an oxide, hydroxide, nitrate, oxalate, organic alkoxide, or carbonate corresponding to each element. The organic monomer is one or more selected from acrylamide (AM), methylenebisacrylamide (MBAM), styrene, butadiene, and methyl methacrylate. The solvent is one or more selected from water, N-methyl-2-pyrrolidone, phthalate, diester, long-chain alcohol, and pyrrolidone. The initiator is one or more selected from benzoyl peroxide, (NH4)2S2O8, and K2S2O8. The catalyst is N,N,N′N′-tetramethylethylenediamine (TEMED). Mixing is performed using a ball milling apparatus selected from planetary ball mills and high-energy ball mills.

[0053] According to another embodiment of method I of the present invention, in step (1-2), the temperature of the polymerization reaction is 80 to 200°C, preferably 90 to 150°C, and more preferably 96 to 120°C.

[0054] According to another embodiment of method I of the present invention, in steps (1-3), the pre-sintering temperature is 300 to 600°C, preferably 350 to 575°C, more preferably 380 to 560°C, and the pre-sintering duration is 2 to 6 hours, preferably 2 to 5 hours, more preferably 2 to 4 hours. The pre-sintering is carried out in an oxygen-containing atmosphere, such as air or oxygen.

[0055] According to another embodiment of method I of the present invention, in steps (1-4), the sintering temperature is 650 to 900°C, preferably 700 to 875°C, more preferably 730 to 860°C, and the sintering duration is 4 to 10 hours, preferably 5 to 9 hours, more preferably 6 to 8 hours. Sintering is carried out in an oxygen-containing atmosphere, such as air or oxygen.

[0056] According to another embodiment of method I according to the invention, in step (1-5), the average particle size D of the slurry is... 50 The wavelength range is 5nm to 500nm, preferably 10nm to 300nm, and more preferably 50nm to 100nm. Drying is performed using a method selected from forced-air drying, vacuum drying, and freeze drying.

[0057] On the other hand, the present invention also relates to a NASICON-type solid electrolyte prepared according to method I of the present invention.

[0058] On the other hand, the present invention also relates to a coated positive electrode material, wherein the matrix of the positive electrode material is coated with a NASICON-type solid electrolyte according to the present invention.

[0059] According to one embodiment of the coated cathode material of the present invention, based on the matrix of the cathode material, the mass fraction of the NASICON-type solid electrolyte is 0.05 to 1.00%, preferably 0.28 to 0.9%, and more preferably 0.41 to 0.84%. The coated cathode material exhibits characteristic titration peaks between pH 5 and 8 after acid-base titration treatment. This indicates that Li3PO4 is generated at the interface between the NASICON solid electrolyte and the matrix during the coating process in the present invention. This product is a fast ion conductor and can act as a buffer layer to balance the potential difference between the NASICON solid electrolyte and the cathode material, alleviate the formation of a space charge layer, and reduce interfacial impedance, thereby allowing the electrochemical performance of the cathode material to be better utilized.

[0060] According to another embodiment of the coated cathode material of the present invention, the matrix of the cathode material is one or more layered oxides selected from lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese aluminum oxide, lithium-rich manganese-based oxide and its derivatives, or lithium iron phosphate, lithium manganese iron phosphate.

[0061] On the other hand, the present invention also relates to a method II for preparing the coated cathode material according to the present invention, comprising the following steps:

[0062] (2-1) The NASICON-type solid electrolyte is mixed with the matrix of the positive electrode material, and (2-2) the coated positive electrode material is obtained by heat treatment.

[0063] According to one embodiment of method II of the present invention, in step (2-1), the ratio of the NASICON-type solid electrolyte to the matrix of the positive electrode material is 0.05:100 to 1:100, preferably 0.28:100 to 0.9:100, and more preferably 0.41:100 to 0.84:100. Mixing is performed using a mixing device selected from ball mills, high-speed mixers, vertical, horizontal, and inclined mixers.

[0064] According to another embodiment of method II of the invention, in step (2-2), the temperature of the heat treatment is 300 to 700°C, preferably 375 to 625°C, more preferably 420 to 580°C. The duration of the heat treatment is 2 to 10 hours, preferably 4 to 10 hours, more preferably 5 to 10 hours. The heat treatment is performed using a heating device selected from tube furnaces, atmosphere furnaces, muffle furnaces, and roller kilns.

[0065] The multi-site doped NASICON-structured solid electrolyte obtained in this invention incorporates dopant elements introduced during thermal polymerization, achieving atomic-level homogeneous mixing between the elements and the main phase. The prepared solid electrolyte exhibits uniform composition, high ionic conductivity, and an average particle size reaching the nanometer scale. The presence of dopant elements within the crystal lattice contributes to its excellent structural stability, allowing the nanoscale slurry to maintain a pure phase state for extended periods without phase decomposition. The prepared nanoscale solid electrolyte slurry and powder possess high specific surface area and strong specific surface energy, making them suitable for the fabrication of composite solid electrodes and ceramic-coated separators.

[0066] This invention provides a gel casting method for preparing NASICON-structured solid electrolytes, which features simple operation, high controllability, and ease of mass production.

[0067] The multi-electrode cathode material coated with NASICON-type solid electrolyte obtained by this invention exhibits uniform distribution of the solid electrolyte on its surface. Acid-base titration treatment reveals distinct characteristic titration peaks between pH 5 and 8. The surface coating with NASICON-type solid electrolyte gives the material high capacity, excellent rate capability, cycling performance, and thermal stability.

[0068] Example

[0069] Comparative Example 1

[0070] LiNi, a multi-element cathode material 0.93 Co 0.05 Mn 0.02 O2 was used to heat-treat LiNi at 500℃ for 6 hours in an atmosphere furnace to obtain heat-treated LiNi. 0.93 Co 0.05 Mn 0.02 O2 material. Following the steps described in Test Example 3, two titration curves were obtained for the sample at pH = 4.6 and pH = 8.5. Following the steps described in Test Example 4, the sample's 0.1C discharge specific capacity in a solid-state battery was 204 mAh / g; the capacity retention after 50 cycles at 1C was 85.6%. Following Test Example 5, the exothermic peak was located at 194℃.

[0071] Comparative Example 2

[0072] LiNi, a multi-element cathode material 0.6 Co 0.1 Mn 0.3 Heat treatment with O2 at 550℃ for 6 hours in an atmosphere furnace yielded heat-treated LiNi. 0.6 Co 0.1 Mn 0.3 O2 material. Following the steps described in Test Example 3, two titration curves were obtained for the sample at pH = 4.5 and pH = 8.3. Following the steps described in Test Example 4, the sample's 0.1C discharge specific capacity in a solid-state battery was 196 mAh / g; the capacity retention rate after 50 cycles at 1C was 90.2%. Following Test Example 5, the exothermic peak was located at 241℃.

[0073] Comparative Example 3

[0074] Step (1-1): Weigh the compounds Li2CO3, Al2O3, TiO2, and NH4H2PO4 according to the stoichiometric ratio, and mix them in a ball mill at 900 rpm for 6 hours to obtain a mixture;

[0075] Step (1-2): The mixture obtained in step (1-1) is pre-sintered in a muffle furnace at 700℃ for 2 hours. The sintered product is then crushed in a high-speed blender for 5 minutes to obtain a powdered solid electrolyte precursor.

[0076] Steps (1-3): The solid electrolyte precursor obtained in step (1-2) is sintered in a muffle furnace at 950℃ for 6 hours. The sintered product is then crushed in an air jet mill to obtain powdered, micron-sized solid electrolyte Li. 1.3 Al 0.3 Ti 1.7 (PO4)3.

[0077] Step (1-4): The solid electrolyte Li obtained in step (1-3) 1.3 Al 0.3 Ti 1.7 (PO4)3 was mixed with pure water and milled in a sand mill at 1000 rpm for 2 hours to obtain a solid content of 50% and D. 50 A nano-sized slurry with a particle size of 0.2 μm was freeze-dried to obtain a powdery, nano-sized solid electrolyte, Li. 1.3 Al 0.3 Ti 1.7 (PO4)3.

[0078] XRD characterization of the prepared solid electrolyte revealed that the bulk sample was a pure phase. Ionic conductivity and structural stability were tested following the procedures described in Test Examples 1 and 2. The results showed that the ionic conductivity of the sample was 3.7 × 10⁻⁶. -5 The S / cm ratio indicates that the sample underwent a phase transformation and exhibited a large amount of alumina impurities after treatment using an abusive method, resulting in poor structural stability. The cell volume calculated from the XRD data is 1.31031 nm. 3 .

[0079] Step (2-1): The nanoscale solid electrolyte Li obtained in step (1-4) 1.3 Al 0.3 Ti 1.7 (PO4)3 powder and LiNi multi-element cathode material 0.93 Co 0.05 Mn 0.02 O2 was weighed at a mass ratio of 1.5:100 and mixed evenly in a high-speed mixer.

[0080] Step (2-2): The mixture obtained in step (2-1) is heat-treated at 750℃ for 12 hours in an atmosphere furnace to obtain Li. 1.3 Al 0.3 Ti 1.7 (PO4)3 powder-coated LiNi 0.93 Co 0.05 Mn 0.02 O2 materials.

[0081] Following the steps described in Test Example 3, three titration curves were obtained for the sample at pH = 4.8, pH = 8.1, and pH = 9.0. Following the steps described in Test Example 4, the sample's 0.1C discharge specific capacity in a solid-state battery was 207 mAh / g; the capacity retention rate after 50 cycles at 1C was 87.8%. Following Test Example 5, the exothermic peak was located at 200℃.

[0082] Comparative Example 4

[0083] Step (1-1): Weigh the compounds Li2CO3, Al2O3, TiO2, and NH4H2PO4 according to the stoichiometric ratio, and mix them in a ball mill at 900 rpm for 6 hours to obtain a mixture;

[0084] Step (1-2): The mixture obtained in step (1-1) is pre-sintered in a muffle furnace at 700℃ for 2 hours. The sintered product is then crushed in a high-speed blender for 5 minutes to obtain a powdered solid electrolyte precursor.

[0085] Steps (1-3): The solid electrolyte precursor obtained in step (1-2) is sintered in a muffle furnace at 950℃ for 6 hours. The sintered product is then crushed in an air jet mill to obtain powdered, micron-sized solid electrolyte Li. 1.1 Ca 0.1 Al 0.3 Ti 1.7 (PO4)3.

[0086] Step (1-4): The solid electrolyte Li obtained in step (1-3) 1.1 Ca 0.1 Al 0.3 Ti 1.7 (PO4)3 was mixed with pure water and milled in a sand mill at 1200 rpm for 2 hours to obtain a solid content of 50% and D. 50 A nano-sized slurry with a particle size of 0.2 μm was freeze-dried to obtain a powdery, nano-sized solid electrolyte, Li. 1.1 Ca 0.1 Al 0.3 Ti 1.7 (PO4)3.

[0087] XRD characterization of the prepared solid electrolyte revealed that the bulk sample was a pure phase, but some AlPO4 impurity peaks were present. Ionic conductivity and structural stability were tested following the procedures described in Test Examples 1 and 2. The results showed that the ionic conductivity of the sample was 3.7 × 10⁻⁶. -5The S / cm concentration indicates that the sample underwent a phase transformation and exhibited a large amount of alumina impurities after treatment using an abusive method, resulting in poor structural stability. The cell volume calculated from the XRD data is 1.3102 nm. 3 The difference between the volume and the standard unit cell volume is 0.00011 nm. 3 .

[0088] Step (2-1): The nanoscale solid electrolyte Li obtained in step (1-4) 1.1 Ca 0.1 Al 0.3 Ti 1.7 (PO4)3 powder and LiNi multi-element cathode material 0.6 Co 0.1 Mn 0.3 O2 was weighed at a mass ratio of 1.5:100 and mixed evenly in a high-speed mixer.

[0089] Step (2-2): The mixture obtained in step (2-1) is heat-treated at 750℃ for 12 hours in an atmosphere furnace to obtain Li. 1.1 Ca 0.1 Al 0.3 Ti 1.7 (PO4)3 powder-coated LiNi 0.6 Co 0.1 Mn 0.3 O2 materials.

[0090] Following the steps described in Test Example 3, three titration curves were obtained for the sample at pH = 4.5, pH = 8.1, and pH = 8.6. Following the steps described in Test Example 4, the sample's 0.1C discharge specific capacity in a solid-state battery was 194 mAh / g; the capacity retention rate after 50 cycles at 1C was 92.5%. Following Test Example 5, the exothermic peak was located at 249℃.

[0091] Example 1

[0092] Step (1-1): Weigh the compounds of Li2CO3, Al2O3, TiO2, and NH4H2PO4 according to the stoichiometric ratio, add a certain amount of pure water and mix. Then, mix and crush the mixture in a ball mill to obtain a mixed slurry A with a solid content of 50%. Add 55% by weight of acrylamide (monomer), (NH4)2S2O8 (initiator) and TEMED (catalyst) to mixed slurry A and disperse them evenly in a stirring device to obtain mixed slurry B.

[0093] Step (1-2): Pour the mixed slurry B into a crucible container and dry it in a 100°C forced-air oven to initiate the polymerization reaction of the substances in the mixed slurry B. After 12 hours, a block-shaped solid electrolyte precursor A is obtained.

[0094] Steps (1-3): The solid electrolyte precursor A obtained in step (2) is pre-sintered in a muffle furnace at 500°C for 2 hours. The sintered product is then crushed in a high-speed blender for 5 minutes to obtain powdered solid electrolyte precursor B.

[0095] Steps (1-4): The solid electrolyte precursor B obtained in step (3) is sintered in a muffle furnace at 750°C for 6 hours. The sintered product is then crushed in an air jet mill to obtain powdered, micron-sized solid electrolyte Li. 1.3 Al 0.3 Ti 1.7 (PO4)3.

[0096] Steps (1-5): The solid electrolyte Li obtained in step (4) 1.3 Al 0.3 Ti 1.7 (PO4)3 was milled with pure water in a sand mill at 1000 rpm for 2 hours to obtain a nano-sized slurry with a solid content of 50%. The slurry was then freeze-dried, and the resulting powder was further dissociated using an air jet mill to obtain a powdery, nano-sized solid electrolyte, Li. 1.3 Al 0.3 Ti 1.7 (PO4)3.

[0097] XRD characterization of the prepared solid electrolyte revealed that the sample was a pure phase. Ionic conductivity and structural stability were tested following the procedures described in Test Examples 1 and 2. The results showed that the ionic conductivity of the sample was 1.3 × 10⁻⁶. -4 The S / cm concentration indicates that a small amount of alumina impurities appeared in the sample after treatment with the abusive method, suggesting a phase transformation and poor structural stability. The cell volume calculated from the XRD test data is 1.33 nm. 3 The difference between the volume and the standard unit cell volume is 0.01969 nm. 3 .

[0098] Step (2-1): The nanoscale solid electrolyte Li obtained in step (1-5) 1.3 Al 0.3 Ti 1.7 (PO4)3 powder and LiNi multi-element cathode material 0.93 Co 0.05 Mn 0.02 O2 was weighed at a mass ratio of 0.8:100 and mixed evenly in a high-speed mixer.

[0099] Step (2-2): The mixture obtained in step (2-1) is heat-treated at 500℃ for 6 hours in an atmosphere furnace to obtain Li.1.3 Al 0.3 Ti 1.7 (PO4)3 powder-coated LiNi 0.93 Co 0.05 Mn 0.02 O2 materials.

[0100] Following the steps described in Test Example 3, three titration curves were obtained for the sample at pH = 6.1, pH = 7.6, and pH = 9.0. Following the steps described in Test Example 4, the sample's 0.1C discharge specific capacity in a solid-state battery was 210 mAh / g. The capacity retention rate after 50 cycles at 1C was 89.9%. Following the steps described in Test Example 5, the DSC exothermic peak of the sample was located at 205℃.

[0101] Example 2

[0102] Step (1-1): Weigh the compounds of Li2CO3, MgCO3, Al2O3, TiO2, and NH4H2PO4 according to the stoichiometric ratio, add a certain amount of pure water and mix. Then, mix and crush the mixture in a ball mill to obtain a mixed slurry A with a solid content of 50%. Add 55% by weight of acrylamide (monomer), (NH4)2S2O8 (initiator) and TEMED (catalyst) to the mixed slurry A and disperse it evenly in a stirring device to obtain mixed slurry B.

[0103] Step (1-2): Pour the mixed slurry B into a crucible container and dry it in a 100°C forced-air oven to initiate the polymerization reaction of the substances in the mixed slurry B. After 12 hours, a block-shaped solid electrolyte precursor A is obtained.

[0104] Steps (1-3): The solid electrolyte precursor A obtained in step (2) is pre-sintered in a muffle furnace at 450°C for 2 hours. The sintered product is then crushed in a high-speed blender for 3 minutes to obtain powdered solid electrolyte precursor B.

[0105] Steps (1-4): The solid electrolyte precursor B obtained in step (3) is sintered in a muffle furnace at 800℃ for 6 hours. The sintered product is then crushed in an air jet mill to obtain powdered, micron-sized solid electrolyte Li. 1.2 Mg 0.05 Al 0.3 Ti 1.7 (PO4)3.

[0106] Steps (1-5): The solid electrolyte Li obtained in step (4) 1.2 Mg 0.05 Al 0.3 Ti 1.7(PO4)3 was milled with pure water in a sand mill at 1000 rpm for 2 hours to obtain a nano-sized slurry with a solid content of 50%. The slurry was then freeze-dried, and the resulting powder was further dissociated using an air jet mill to obtain a powdery, nano-sized solid electrolyte, Li. 1.2 Mg 0.05 Al 0.3 Ti 1.7 (PO4)3.

[0107] XRD characterization of the prepared solid electrolyte revealed that the sample was a pure phase. Ionic conductivity and structural stability were tested following the procedures described in Test Examples 1 and 2. The results showed that the sample's ionic conductivity was 5.2 × 10⁻⁶. -4 The sample, treated with an abusive method, showed virtually no impurities and exhibited good structural stability (S / cm). The cell volume calculated from XRD data was 1.35 nm. 3 The difference between the volume and the standard unit cell volume is 0.03969 nm. 3 .

[0108] Step (2-1): The nanoscale solid electrolyte Li obtained in step (1-5) 1.2 Mg 0.05 Al 0.3 Ti 1.7 (PO4)3 powder and LiNi multi-element cathode material 0.93 Co 0.05 Mn 0.02 O2 is weighed at a mass ratio of 0.5:100 and mixed evenly in a high-speed mixer.

[0109] Step (2-2): The mixture obtained in step (2-1) is heat-treated at 550℃ for 6 hours in an atmosphere furnace to obtain Li. 1.2 Mg 0.05 Al 0.3 Ti 1.7 (PO4)3 powder-coated LiNi 0.93 Co 0.05 Mn 0.02 O2 materials.

[0110] Following the steps described in Test Example 3, three titration curves were obtained for the sample at pH = 4.4, pH = 6.1, and pH = 8.9. Following the steps described in Test Example 4, the sample's 0.1C discharge specific capacity in a solid-state battery was 218 mAh / g. The capacity retention after 50 cycles at 1C was 90.4%. Following the steps described in Test Example 5, the DSC exothermic peak of the sample was located at 207℃.

[0111] Example 3

[0112] Step (1-1): Weigh the compounds Li2CO3, Al2O3, GeO2, ZrO2, and NH4H2PO4 according to the stoichiometric ratio, add a certain amount of pure water and mix. Then, mix and crush the mixture in a ball mill to obtain a mixed slurry A with a solid content of 50%. Add 55% by weight of acrylamide (monomer), (NH4)2S2O8 (initiator), and TEMED (catalyst) to mixed slurry A and disperse them evenly in a stirring device to obtain mixed slurry B.

[0113] Step (1-2): Pour the mixed slurry B into a crucible container and dry it in a 100°C forced-air oven to initiate the polymerization reaction of the substances in the mixed slurry B. After 12 hours, a block-shaped solid electrolyte precursor A is obtained.

[0114] Steps (1-3): The solid electrolyte precursor A obtained in step (2) is pre-sintered in a muffle furnace at 400°C for 3 hours, and the sintered product is crushed in a high-speed blender for 5 minutes to obtain powdered solid electrolyte precursor B.

[0115] Steps (1-4): The solid electrolyte precursor B obtained in step (3) is sintered in a muffle furnace at 850°C for 8 hours. The sintered product is then crushed in an air jet mill to obtain powdered, micron-sized solid electrolyte Li. 1.3 Al 0.3 Zr 0.05 Ge 1.65 (PO4)3.

[0116] Steps (1-5): The solid electrolyte Li obtained in step (4) 1.3 Al 0.3 Zr 0.05 Ge 1.65 (PO4)3 was milled with pure water in a sand mill at 1000 rpm for 2 hours to obtain a nano-sized slurry with a solid content of 50%. The slurry was then freeze-dried, and the resulting powder was further dissociated using an air jet mill to obtain a powdery, nano-sized solid electrolyte, Li. 1.3 Al 0.3 Zr 0.05 Ge 1.65 (PO4)3.

[0117] XRD characterization of the prepared solid electrolyte revealed that the sample was a pure phase. Ionic conductivity and structural stability were tested following the procedures described in Test Examples 1 and 2. The results showed that the ionic conductivity of the sample was 7.6 × 10⁻⁶. -4 The sample exhibits excellent structural stability with a S / cm ratio and no impurity phases after treatment using the abuse method. The cell volume calculated from the XRD test data is 1.325 nm.3 The difference between the volume and the standard unit cell volume is 0.01469 nm. 3 .

[0118] Step (2-1): The nanoscale solid electrolyte Li obtained in step (1-5) 1.3 Al 0.3 Zr 0.05 Ge 1.65 (PO4)3 powder and LiNi multi-element cathode material 0.93 Co 0.05 Mn 0.02 O2 is weighed at a mass ratio of 0.5:100 and mixed evenly in a high-speed mixer.

[0119] Step (2-2): The mixture obtained in step (2-1) is heat-treated at 550℃ for 6 hours in an atmosphere furnace to obtain Li. 1.3 Al 0.3 Zr 0.05 Ge 1.65 (PO4)3 powder-coated LiNi 0.93 Co 0.05 Mn 0.02 O2 materials.

[0120] Following the steps described in Test Example 3, three titration curves were obtained for the sample at pH = 4.5, pH = 6.7, and pH = 9.1. Following the steps described in Test Example 4, the sample's 0.1C discharge specific capacity in a solid-state battery was 220 mAh / g. The capacity retention rate after 50 cycles at 1C was 91.0%. Following the steps described in Test Example 5, the DSC exothermic peak of the sample was located at 208℃.

[0121] Example 4

[0122] Step (1-1): Weigh the compounds Li2CO3, MgCO3, Al2O3, TiO2, ZrO2, and NH4H2PO4 according to the stoichiometric ratio, add a certain amount of pure water and mix. Then, mix and crush the mixture in a ball mill to obtain a mixed slurry A with a solid content of 50%. Add 55% by weight of acrylamide (monomer), (NH4)2S2O8 (initiator) and TEMED (catalyst) to mixed slurry A and disperse them evenly in a stirring device to obtain mixed slurry B.

[0123] Step (1-2): Pour the mixed slurry B into a crucible container and dry it in a 100°C forced-air oven to initiate the polymerization reaction of the substances in the mixed slurry B. After 12 hours, a block-shaped solid electrolyte precursor A is obtained.

[0124] Steps (1-3): The solid electrolyte precursor A obtained in step (2) is pre-sintered in a muffle furnace at 550°C for 2 hours. The sintered product is then crushed in a high-speed blender for 5 minutes to obtain powdered solid electrolyte precursor B.

[0125] Steps (1-4): The solid electrolyte precursor B obtained in step (3) is sintered in a muffle furnace at 800℃ for 6 hours. The sintered product is then crushed in an air jet mill to obtain powdered, micron-sized solid electrolyte Li. 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti 1.65 (PO4)3.

[0126] Steps (1-5): The solid electrolyte Li obtained in step (4) 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti 1.65 (PO4)3 was milled with pure water in a sand mill at 1000 rpm for 2 hours to obtain a nano-sized slurry with a solid content of 50%. The slurry was then freeze-dried, and the resulting powder was further dissociated using an air jet mill to obtain a powdery, nano-sized solid electrolyte, Li. 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti 1.65 (PO4)3.

[0127] XRD characterization of the prepared solid electrolyte revealed that the sample was a pure phase. Ionic conductivity and structural stability were tested following the procedures described in Test Examples 1 and 2. The results showed that the sample's ionic conductivity was 9.5 × 10⁻⁶. -4 The sample exhibits excellent structural stability with a S / cm ratio and no impurities after treatment using the abuse method. The cell volume calculated from the XRD test data is 1.33 nm. 3 The difference between the volume and the standard unit cell volume is 0.01969 nm. 3 .

[0128] Step (2-1): The nanoscale solid electrolyte Li obtained in step (1-5) 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti 1.65 (PO4)3 powder and LiNi multi-element cathode material 0.93 Co 0.05 Mn 0.02O2 was weighed at a mass ratio of 0.6:100 and mixed evenly in a high-speed mixer.

[0129] Step (2-2): The mixture obtained in step (2-1) is heat-treated in an atmosphere furnace at 450℃ for 10 hours to obtain Li. 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti 1.65 (PO4)3 powder-coated LiNi 0.93 Co 0.05 Mn 0.02 O2 materials.

[0130] Following the steps described in Test Example 3, three titration curves were obtained for the sample at pH = 4.8, pH = 7.5, and pH = 10.4, as shown below. Figure 3 As shown. Following the steps described in Test Example 4, the sample's 0.1C discharge specific capacity in a solid-state battery was measured to be 223 mAh / g. The capacity retention after 50 cycles at 1C was 91.8%. Following the steps described in Test Example 5, the DSC exothermic peak of the sample was located at 210℃.

[0131] Example 5

[0132] Step (1-1): Weigh the compounds Li2CO3, MgCO3, Al2O3, GeO2, YO2, and NH4H2PO4 according to the stoichiometric ratio, add a certain amount of pure water and mix. Then, mix and crush the mixture in a ball mill to obtain a mixed slurry A with a solid content of 50%. Add 55% by weight of acrylamide (monomer), (NH4)2S2O8 (initiator) and TEMED (catalyst) to mixed slurry A and disperse them evenly in a stirring device to obtain mixed slurry B.

[0133] Step (1-2): Pour the mixed slurry B into a crucible container and dry it in a 100°C forced-air oven to initiate the polymerization reaction of the substances in the mixed slurry B. After 12 hours, a block-shaped solid electrolyte precursor A is obtained.

[0134] Steps (1-3): The solid electrolyte precursor A obtained in step (2) is pre-sintered in a muffle furnace at 500°C for 2 hours. The sintered product is then crushed in a high-speed blender for 5 minutes to obtain powdered solid electrolyte precursor B.

[0135] Steps (1-4): The solid electrolyte precursor B obtained in step (3) is sintered in a muffle furnace at 850°C for 8 hours. The sintered product is then crushed in an air jet mill to obtain powdered, micron-sized solid electrolyte Li. 1.2 Mg 0.05 Al0.3 Y 0.05 Ge 1.65 (PO4)3.

[0136] Steps (1-5): The solid electrolyte Li obtained in step (4) 1.2 Mg 0.05 Al 0.3 Y 0.05 Ge 1.65 (PO4)3 was milled with pure water in a sand mill at 1000 rpm for 2 hours to obtain a nano-sized slurry with a solid content of 50%. The slurry was then freeze-dried, and the resulting powder was further dissociated using an air jet mill to obtain a powdery, nano-sized solid electrolyte, Li. 1.2 Mg 0.05 Al 0.3 Y 0.05 Ge 1.65 (PO4)3.

[0137] XRD characterization of the prepared solid electrolyte revealed that the sample was a pure phase. Ionic conductivity and structural stability were tested following the procedures described in Test Examples 1 and 2. The results showed that the sample's ionic conductivity was 8.3 × 10⁻⁶. -4 The sample exhibits excellent structural stability with a S / cm ratio and no impurity phases after treatment using the abuse method. The cell volume calculated from the XRD test data is 1.41 nm. 3 The difference between the volume and the standard unit cell volume is 0.09969 nm. 3 .

[0138] Step (2-1): The nanoscale solid electrolyte Li obtained in step (1-5) 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti 1.65 (PO4)3 powder and LiNi multi-element cathode material 0.6 Co 0.1 Mn 0.3 O2 was weighed at a mass ratio of 0.6:100 and mixed evenly in a high-speed mixer.

[0139] Step (2-2): The mixture obtained in step (2-1) is heat-treated in an atmosphere furnace at 450℃ for 10 hours to obtain Li. 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti 1.65 (PO4)3 powder-coated LiNi 0.6 Co 0.1 Mn 0.3 O2 materials.

[0140] Following the steps described in Test Example 3, three titration curves were obtained for the sample at pH = 4.9, pH = 7.2, and pH = 8.8. Following the steps described in Test Example 4, the sample's 0.1C discharge specific capacity in a solid-state battery was 202 mAh / g. The capacity retention rate after 50 cycles at 1C was 96.3%. Following the steps described in Test Example 5, the DSC exothermic peak of the sample was located at 260℃.

[0141] Example 6

[0142] Step (1-1): Weigh the compounds Li2CO3, MgCO3, Sc2O3, ZrO2, TiO2, NH4H2PO4, and NH4Cl according to their stoichiometric ratio, add a certain amount of pure water and mix. Then, mix and crush the mixture in a ball mill to obtain a mixed slurry A with a solid content of 50%. Add 55% by weight of acrylamide (monomer), (NH4)2S2O8 (initiator), and TEMED (catalyst) to mixed slurry A and disperse them evenly in a stirring device to obtain mixed slurry B.

[0143] Step (1-2): Pour the mixed slurry B into a crucible container and dry it in a 100°C forced-air oven to initiate the polymerization reaction of the substances in the mixed slurry B. After 12 hours, a block-shaped solid electrolyte precursor A is obtained.

[0144] Steps (1-3): The solid electrolyte precursor A obtained in step (2) is pre-sintered in a muffle furnace at 500°C for 2 hours. The sintered product is then crushed in a high-speed blender for 5 minutes to obtain powdered solid electrolyte precursor B.

[0145] Steps (1-4): The solid electrolyte precursor B obtained in step (3) is sintered in a muffle furnace at 850°C for 8 hours. The sintered product is then crushed in an air jet mill to obtain powdered, micron-sized solid electrolyte Li. 1.2 Mg 0.05 Sc 0.3 Zr 0.05 Ti 1.65 (PO4)2(ClO2)3.

[0146] Steps (1-5): The solid electrolyte Li obtained in step (4) 1.2 Mg 0.05 Sc 0.3 Zr 0.05 Ti 1.65(PO4)2(ClO2)3 was milled with pure water in a sand mill at 1000 rpm for 2 hours to obtain a nano-sized slurry with a solid content of 50%. The slurry was then freeze-dried, and the resulting powder was further dissociated using an air jet mill to obtain a powdery, nano-sized solid electrolyte, Li. 1.2 Mg 0.05 Sc 0.3 Zr 0.05 Ti 1.65 (PO4)2(ClO2)3.

[0147] XRD characterization of the prepared solid electrolyte revealed that the sample was a pure phase. Ionic conductivity and structural stability were tested following the procedures described in Test Examples 1 and 2. The results showed that the ionic conductivity of the sample was 5.1 × 10⁻⁶. -4 The sample exhibits excellent structural stability with a S / cm ratio and no impurity phases after treatment using the abuse method. The cell volume calculated from the XRD test data is 1.53 nm. 3 The difference between the volume and the standard unit cell volume is 0.21969 nm. 3 .

[0148] Step (2-1): The nanoscale solid electrolyte Li obtained in step (1-5) 1.2 Mg 0.05 Sc 0.3 Zr 0.05 Ti 1.65 (PO4)2(ClO2)3 powder is similar to the multi-element cathode material LiNi 0.6 Co 0.1 Mn 0.3 O2 was weighed at a mass ratio of 0.6:100 and mixed evenly in a high-speed mixer.

[0149] Step (2-2): The mixture obtained in step (2-1) is heat-treated in an atmosphere furnace at 450℃ for 10 hours to obtain Li. 1.2 Mg 0.05 Sc 0.3 Zr 0.05 Ti 1.65 LiNi coated with (PO4)2(ClO2)3 powder 0.6 Co 0.1 Mn 0.3 O2 materials.

[0150] Following the steps described in Test Example 3, three titration curves were obtained for the sample at pH = 4.6, pH = 6.9, and pH = 8.8. Following the steps described in Test Example 4, the sample's 0.1C discharge specific capacity in a solid-state battery was 200 mAh / g. The capacity retention rate after 50 cycles at 1C was 96.5%. Following the steps described in Test Example 5, the DSC exothermic peak of the sample was located at 262℃.

[0151] Example 7

[0152] Step (1-1): Weigh the compounds of Li2CO3, MgCO3, Al2O3, ZrO2, TiO2, NH4H2PO4, and SiO2 according to the stoichiometric ratio, add a certain amount of pure water and mix. Then, mix and crush the mixture in a ball mill to obtain a mixed slurry A with a solid content of 50%. Add 55% by weight of acrylamide (monomer), (NH4)2S2O8 (initiator), and TEMED (catalyst) to the mixed slurry A and disperse them evenly in a stirring device to obtain mixed slurry B.

[0153] Step (1-2): Pour the mixed slurry B into a crucible container and dry it in a 100°C forced-air oven to initiate the polymerization reaction of the substances in the mixed slurry B. After 12 hours, a block-shaped solid electrolyte precursor A is obtained.

[0154] Steps (1-3): The solid electrolyte precursor A obtained in step (2) is pre-sintered in a muffle furnace at 500°C for 2 hours. The sintered product is then crushed in a high-speed blender for 5 minutes to obtain powdered solid electrolyte precursor B.

[0155] Steps (1-4): The solid electrolyte precursor B obtained in step (3) is sintered in a muffle furnace at 850°C for 8 hours. The sintered product is then crushed in an air jet mill to obtain powdered, micron-sized solid electrolyte Li. 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti 1.65 (PO4)(SiO3)3.

[0156] Steps (1-5): The solid electrolyte Li obtained in step (4) 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti 1.65(PO4)(SiO3)3 was milled with pure water in a sand mill at 1000 rpm for 2 hours to obtain a nano-sized slurry with a solid content of 50%. The slurry was then freeze-dried, and the resulting powder was further dissociated using an air jet mill to obtain a powdery, nano-sized solid electrolyte, Li. 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti 1.65 (PO4)(SiO3)3.

[0157] XRD characterization of the prepared solid electrolyte revealed that the sample was a pure phase. Ionic conductivity and structural stability were tested following the procedures described in Test Examples 1 and 2. The results showed that the sample's ionic conductivity was 4.5 × 10⁻⁶. -4 The sample exhibits excellent structural stability with a S / cm ratio and no impurity phases after treatment using the abuse method. The cell volume calculated from the XRD test data is 1.55 nm. 3 The difference between the volume and the standard unit cell volume is 0.23969 nm. 3 .

[0158] Step (2-1): The nanoscale solid electrolyte Li obtained in step (1-5) 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti 1.65 (PO4)(SiO3)3 powder and LiNi multi-element cathode material 0.6 Co 0.1 Mn 0.3 O2 was weighed at a mass ratio of 0.6:100 and mixed evenly in a high-speed mixer.

[0159] Step (2-2): The mixture obtained in step (2-1) is heat-treated in an atmosphere furnace at 450℃ for 10 hours to obtain Li. 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti 1.65 LiNi coated with (PO4)(SiO3)3 powder 0.6 Co 0.1 Mn 0.3 O2 materials.

[0160] Following the steps described in Test Example 3, three titration curves were obtained for the sample at pH = 4.5, pH = 7.5, and pH = 9.0. Following the steps described in Test Example 4, the sample's 0.1C discharge specific capacity in a solid-state battery was 203 mAh / g. The capacity retention rate after 50 cycles at 1C was 96.0%. Following the steps described in Test Example 5, the DSC exothermic peak of the sample was located at 260℃.

[0161] Test Example 1

[0162] Ten grams of each of the solid electrolyte samples prepared in the comparative examples and embodiments were taken. Two grams of the sample were placed in a mold with a diameter of 11 mm and pressed into a dense disc under a pressure of 100 MPa. The disc was then placed in a covered alumina crucible, and the remaining 8 grams of sample powder were used to evenly cover the disc. The disc was sintered at 1200 °C for 8 hours. The disc was then removed and polished to obtain a sintered and dense lithium lanthanum zirconium oxide solid electrolyte ceramic disc. The prepared solid electrolyte ceramic disc was placed in an electrochemical workstation to test the AC impedance at room temperature. The frequency was set to 0.01-10 MPa. Based on the impedance data obtained from the test, the ionic conductivity of the sample was calculated using the formula σ = L / RS (σ is the conductivity, L is the thickness of the ceramic disc, R is the impedance value, and S is the area of ​​the ceramic disc). The test and calculation results corresponded to the samples of the different comparative examples and embodiments described above.

[0163] Test Example 2

[0164] Take 10 grams of each of the solid electrolyte samples prepared in the comparative examples and embodiments above, and place them in 90 grams of boiling water at 100°C and stir for 2 hours. Evaporate and dry the stirred samples, and then perform XRD tests.

[0165] Test Example 3

[0166] Weigh 5 grams of the sample to be tested and add it to 95 grams of room temperature deionized water (M water). Stir for 5 minutes. Filter the stirred slurry through a Buchner funnel with filter paper to obtain a filtrate with a mass of M. Titrate the obtained filtrate in a Metrohm 888 potentiometric titrator at room temperature to obtain a titration curve. Record the equivalence point value EP on the titration curve. x =V x (x = 1, 2, 3, ...).

[0167] Test Example 4

[0168] The solid electrolyte-coated multi-electrode cathode material samples prepared in the comparative examples and embodiments were mixed with conductive carbon black, PVDF, and LiTFSI in a mass ratio of 90:3:5:2. An appropriate amount of NMP was added, and the mixture was stirred until homogeneous. The mixture was then coated onto aluminum foil and dried in a 120°C oven for 1 hour to form a cathode sheet with a diameter of 11 mm. PEO and LiTFSI (molar ratio EO:Li = 12) were dissolved in acetonitrile and stirred for 12 hours. The resulting slurry was poured into a polytetrafluoroethylene mold and vacuum dried in a 50°C oven for 10 hours. The PEO electrolyte membrane was then hot-pressed in a press for 5 minutes and formed into a 19 mm diameter disc-shaped PEO electrolyte membrane. Using lithium metal as the anode, the prepared cathode sheet and PEO electrolyte membrane were assembled into a 2025-type coin cell all-solid-state battery in an Ar gas glove box with a water and oxygen content of less than 5 ppm. The solid-state battery was subjected to charge-discharge capacity testing at 3.0-4.3V, 0.1C, and 60℃. Its charge-discharge cycle performance was tested by performing 50 charge-discharge cycles at 3.0-4.3V, 1C, and 60℃.

[0169] Test Example 5

[0170] The solid electrolyte-coated multi-element positive electrode material samples prepared in the comparative examples and embodiments were mixed with acetylene black and polyvinylidene fluoride (PVDF) at a mass ratio of 95:2.5:2.5, coated onto aluminum foil, and dried. The mixture was then stamped into a positive electrode sheet with a diameter of 12 mm and a thickness of 120 μm under a pressure of 100 MPa. The positive electrode sheet was then dried in a vacuum drying oven at 120°C for 12 hours. The negative electrode used a Li metal sheet with a diameter of 17 mm and a thickness of 1 mm; the separator used a 25 μm thick polyethylene porous membrane; and the electrolyte used was a 1 mol / L mixture of equal parts LiPF6, ethylene carbonate (EC), and diethyl carbonate (DEC). The positive electrode sheet, separator, negative electrode sheet, and electrolyte were assembled into a 2025 type coin cell in an Ar gas glove box with a water content and oxygen content of less than 5 ppm. The above-mentioned button cell was charged and discharged twice at 3.0-4.3V, 0.2C, and 25℃, and then fully charged before being disassembled to obtain the positive electrode. The positive electrode was then tested in a differential thermal-thermogravimetric analyzer to obtain the corresponding DSC curve of the sample.

[0171] In the above embodiments, the difference between the cell volume and the standard value is greater than 0.01, which means that the element doping in the corresponding NASICON-type solid electrolyte enters the cell position to form a solid solution (according to Vegard's law). When the valence state of the doped element is inconsistent with that of the element in the matrix, it will cause the charge balance in the matrix to be maintained in the form of point defects (e.g., a missing atom at a certain position in the cell). These point defects, especially vacancy defects, will increase the lithium ion transport channels and improve ionic conductivity. Some will also cause the reconstruction of the electric field within the cell, improving electronic conductivity. Therefore, the coating layer has excellent ion and electron transport channels, which is beneficial to the capacity and rate capability of the sample. Therefore, the sample capacity in the embodiments is significantly better than that in the comparative examples.

[0172] The example samples exhibited a characteristic titration peak between pH 5 and 8. The presence of this peak indicates that Li3PO4 was generated at the interface between the NASICON solid electrolyte and the substrate during the coating process. Li3PO4 is a fast ion conductor and can act as a buffer layer to balance the potential difference between the NASICON solid electrolyte and the cathode material, mitigating the formation of a space charge layer and reducing interfacial impedance, thereby better utilizing the electrochemical performance of the cathode material. Therefore, the capacity and cycle retention of the example samples were significantly better than those of the comparative samples.

[0173] In the example, the DSC exothermic peak temperature of the sample was significantly higher than that of the comparative example, which reflects the increase in the thermal runaway temperature of the cathode material in the charging state. This indicates that the NASICON solid electrolyte has achieved a dense coating of the cathode material matrix and has excellent structural stability. Only by achieving both of the above effects at the same time can the side reactions between the electrolyte and the cathode material matrix be delayed, especially in maintaining the relative stability of the structure in the charging state, and improving the thermal runaway temperature and corresponding safety performance.

[0174] While specific embodiments have been described, these embodiments are given by way of example only and are not intended to limit the scope of the invention. The appended claims and their equivalents are intended to cover all modifications, substitutions, and alterations that fall within the scope and spirit of the invention.

Claims

1. NASICON type solid electrolyte conforming to the following formula, Li x M 1 y M 2 z M 3 u (PO4) w1 (RO v ) w2 in, M 1 It is at least one element selected from Mg, Na, and K. M 2 It is at least one element selected from Al, Ga, In, Y, and Sc. M 3 It is at least one element selected from Ti, Zr, and Ge. R is at least one element selected from Si, Cl, Br, S, Sb, and Sn. 0.6≤x<3.2， 0.05≤y≤0.5， 0.2≤z≤0.7， 0.9≤u≤5.4， The conditions are: 1≤v≤3, 1≤w1≤3, 0≤w2≤3, and the total charge of the anions is 9. The cell volume of the NASICON-type solid electrolyte, calculated from XRD test data, is 1.35 nm. 3 ~1.55nm 3 ; The method for preparing the NASICON-type solid electrolyte includes the following steps: (1-1) The raw material compound of NASICON type solid electrolyte is mixed with organic monomer and solvent, crushed to obtain mixture A, and then an initiator and catalyst are added to obtain mixture B; (1-2) The mixture B is poured into a container and heated to initiate a polymerization reaction to obtain a bulk solid electrolyte precursor A; (1-3) The solid electrolyte precursor A is pre-sintered and then crushed to obtain powdered solid electrolyte precursor B; (1-4) The solid electrolyte precursor B is sintered and then crushed to obtain powdered, micron-sized solid electrolyte A; and (1-5) The solid electrolyte A is ground to obtain a slurry with nano-sized particles, and then dried to obtain a powdery, nano-sized NASICON-type solid electrolyte.

2. The NASICON-type solid electrolyte according to claim 1, characterized in that, The average particle size D of the NASICON-type solid electrolyte 50 The range is from 0.01 to 5 μm.

3. The NASICON-type solid electrolyte according to claim 1, characterized in that, The specific surface area of ​​the NASICON-type solid electrolyte is >10 m². 2 / g.

4. The NASICON-type solid electrolyte according to claim 1, characterized in that, The pH of the NASICON-type solid electrolyte is >5.

5. The NASICON-type solid electrolyte according to claim 1, characterized in that, The NASICON-type solid electrolyte has an ionic conductivity >10. -4 S / cm.

6. The NASICON-type solid electrolyte according to claim 1, characterized in that, The raw material compounds of the NASICON-type solid electrolyte are oxides, hydroxides, nitrates, oxalates, organic alkoxides, or carbonates corresponding to each element.

7. The NASICON-type solid electrolyte according to claim 1, characterized in that, The organic monomer is selected from one or more of acrylamide (AM), methylenebisacrylamide (MBAM), styrene, butadiene, and methyl methacrylate.

8. The NASICON-type solid electrolyte according to claim 1, characterized in that, The solvent is selected from one or more of water, N-methyl-2-pyrrolidone, phthalate, diester, long-chain alcohol and pyrrolidone.

9. The NASICON-type solid electrolyte according to claim 1, characterized in that, The initiator is one or more selected from benzoyl peroxide, (NH4)2S2O8 and K2S2O8.

10. The NASICON-type solid electrolyte according to claim 1, characterized in that, The catalyst is N,N,N′,N′-tetramethylethylenediamine (TEMED).

11. The NASICON-type solid electrolyte according to claim 1, characterized in that, The polymerization reaction is carried out at a temperature of 80 to 200°C.

12. The NASICON-type solid electrolyte according to claim 1, characterized in that, The pre-sintering temperature is 300 to 600°C, and the pre-sintering duration is 2 to 6 hours.

13. The NASICON-type solid electrolyte according to claim 1, characterized in that, The sintering temperature is 650 to 900°C, and the sintering duration is 4 to 10 hours.

14. The NASICON-type solid electrolyte according to claim 1, characterized in that, The average particle size D of the slurry 50 The range is from 5nm to 500nm.

15. A coated cathode material, characterized in that, The matrix of the positive electrode material is coated with a NASICON-type solid electrolyte according to any one of claims 1 to 14.

16. The coated cathode material according to claim 15, characterized in that, Based on the matrix of the cathode material, the mass fraction of the NASICON-type solid electrolyte is 0.05 to 1.00%.

17. The coated cathode material according to claim 16, characterized in that, The coated cathode material exhibits characteristic titration peaks between pH 5 and 8 after acid-base titration treatment.

18. The coated cathode material according to claim 17, characterized in that, The matrix of the cathode material is one or more layered oxides selected from lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese aluminum oxide, lithium-rich manganese-based oxide, or lithium iron phosphate or lithium manganese iron phosphate.

19. A method for preparing the coated cathode material according to any one of claims 15 to 18, comprising the following steps: (2-1) Mix the NASICON-type solid electrolyte with the matrix of the positive electrode material; (2-2) The coated cathode material is obtained by heat treatment.

20. The method according to claim 19, characterized in that, The ratio of the NASICON-type solid electrolyte to the matrix of the cathode material is from 0.05:100 to 1:

100.

21. The method according to claim 19, characterized in that, The heat treatment temperature is 300 to 700°C.

22. The method according to claim 19, characterized in that, The heat treatment lasts for 2 to 10 hours.

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