Solid electrolyte material with oxidation-reduction activity as well as preparation method and application of solid electrolyte material

Abstract

The invention belongs to the technical field of energy storage materials and electrochemical devices, and discloses a redox active solid electrolyte material and a preparation method and application thereof. The chemical formula of the oxidation-reduction active solid electrolyte material is Li < x > Fe < y > M < z > B < m > Cl < n >, wherein the values of x, y, z, m and n satisfy 0.01 < = x < = 1, 0.1 < = y < 1.4, 0 < = z < 1.4, 0 < = m < = 4, and 0 < n < = 4; m comprises at least one of La, Sc, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y, Yb and Lu; and B comprises at least one of O, S, Se, N, OH, NO3, PO4 and SO4. The oxidation-reduction active solid electrolyte material has high ion and electron conductivity and intrinsic oxidation-reduction activity, breaks through the passive role that a traditional solid electrolyte is only used as an ion conductor, can be used as an active substance to cooperatively work with a positive electrode material to jointly contribute capacity, and has a good oxidation-reduction effect. And the energy density, the rate capability and the long cycle stability of the total battery are remarkably improved.

Description

A redox-active solid electrolyte material, its preparation method and application Technical Field

[0001] This invention relates to the field of energy storage materials and electrochemical devices, specifically to a redox-active solid electrolyte material and its preparation method. Background Technology

[0002] With the transformation of the global energy structure and the continuous expansion of renewable energy, developing efficient and safe energy storage technologies has become one of the key strategic directions for solving energy and environmental problems. Lithium-ion batteries, due to their high energy density and long cycle life, have been widely used in consumer electronics, electric vehicles, and large-scale energy storage. However, traditional liquid lithium-ion batteries use organic electrolytes, which pose safety hazards such as flammability and leakage, and face challenges such as interfacial side reactions and thermal runaway in the pursuit of higher energy density.

[0003] All-solid-state lithium batteries replace liquid electrolytes with solid electrolytes, fundamentally improving battery safety. They not only prevent short circuits by isolating the positive and negative electrodes, but also support rapid lithium-ion conduction. Furthermore, the all-solid-state system is compatible with high-voltage cathode materials and high-capacity lithium metal anodes, significantly increasing battery energy density and is considered a crucial development direction for next-generation energy storage technology. In solid-state batteries, commonly used oxide cathode materials (such as lithium iron phosphate, lithium cobalt oxide, and ternary materials) have low ionic conductivity. They must rely on solid electrolytes to construct continuous ion transport channels to ensure the full utilization of active materials and effective battery capacity. Therefore, the performance of the solid electrolyte directly affects the overall electrochemical performance of the solid-state battery. In addition, to achieve sufficient ion conduction in the composite cathode, the amount of solid electrolyte added typically needs to reach 30 wt% or more. The introduction of this inactive component significantly reduces the proportion of active materials in the cathode, limiting further improvements in the energy density of all-solid-state batteries.

[0004] Therefore, developing novel solid-state electrolyte materials that combine high ionic conductivity with good interfacial stability to help realize high-energy-density all-solid-state batteries while ensuring safety has become one of the key issues to promote the practical application of this technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a redox active solid electrolyte material, its preparation method, and its application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: Firstly, the present invention provides a redox-active solid electrolyte material, wherein the chemical formula of the redox-active solid electrolyte material is Li x Fe y Mz B m Cl n Wherein, the values ​​of x, y, z, m, and n satisfy 0.01≤x≤1, 0.1≤y<1.4, 0≤z<1.4, 0≤m≤4, and 0<n≤4; M includes at least one of La, Sc, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y, Yb, and Lu; and B includes at least one of O, S, Se, N, OH, NO3, PO4, and SO4.

[0007] The redox-active solid electrolyte material of this invention forms a stable lattice framework based on the FeCl3 crystal structure through solid solution reactions of lithium, iron, and doped metal sources. Within this framework, the introduced lithium ions and doped metal elements optimize ion transport pathways, thereby achieving high room-temperature ionic conductivity. Simultaneously, this framework also possesses moderate electronic conductivity, forming a dual-channel structure that combines rapid lithium-ion and electron transport, providing a foundation for smooth electrochemical reactions and efficient charge compensation within the battery. Furthermore, the redox-active solid electrolyte material of this invention can directly drive valence state changes (e.g., Fe³⁺ / Fe²⁺) of metal ions through the reversible insertion / extraction and insertion of lithium ions in the electrolyte lattice, contributing a significant additional specific capacity. This transforms the solid electrolyte from a traditional "inert" ionic conductor into an "active" capacity-contributing component, compensating for the capacity loss caused by the introduction of inactive components in the composite cathode of solid-state batteries, improving the battery's energy density, and effectively reducing the impact of inactive components on the energy density of the solid electrolyte.

[0008] In a preferred embodiment of the redox-active solid electrolyte material of the present invention, M includes at least one of Sc, Ce, Y, Tm, and Yb; and / or, B includes at least one of O, S, and OH.

[0009] Preferably, M includes Y.

[0010] In a preferred embodiment of the redox-active solid electrolyte material of the present invention, the values ​​of x, y, and z satisfy 0.1≤x≤0.7, 0.4≤y≤1.05, and 0.25≤z≤0.8.

[0011] Preferably, the values ​​of x, y, and z satisfy 0.1≤x≤0.4, 0.5≤y≤0.6, and 0.5≤z≤0.7.

[0012] More preferably, the value of x is a range of one or both of 0.1, 0.2, 0.3, and 0.4; the value of y is a range of one or both of 0.5 and 0.6; and the value of z is a range of one or both of 0.5, 0.55, 0.6, 0.65, and 0.7.

[0013] In a second aspect, the present invention provides a method for preparing the redox-active solid electrolyte material, characterized in that it is selected from one of the following (1)-(2): (1) Under a protective atmosphere, a lithium source, an iron source, and a doped metal source are mixed in stoichiometric ratio and subjected to a high-energy ball milling reaction to obtain the redox-active solid electrolyte; (2) Under a protective atmosphere, an iron source and a doped metal source are mixed and used as a positive electrode, a lithium source is used as a solid electrolyte, and a lithium-indium alloy is used as a negative electrode, and assembled into a full cell for electrochemical treatment to obtain the redox-active solid electrolyte.

[0014] The redox active solid electrolyte prepared by the method of this invention has high room temperature ionic conductivity, high electronic conductivity and good electrochemical stability.

[0015] As a preferred embodiment of the preparation method of the redox active solid electrolyte material of the present invention, in step (1), the lithium source includes at least one of lithium hydroxide, lithium oxide, lithium chloride, lithium carbonate, lithium phosphate, lithium sulfate, and lithium nitrate; the iron source includes ferric chloride; and the doped metal source includes at least one of yttrium trichloride, cerium disulfide, scandium trichloride, thulium trichloride, and ytterbium trichloride.

[0016] Preferably, in step (1), the lithium source includes lithium oxide; and / or, the doped metal source includes yttrium trichloride.

[0017] As a preferred embodiment of the preparation method of the redox active solid electrolyte material of the present invention, in step (2), the lithium source includes lithium zirconium chloride oxychloride; the iron source includes ferric chloride; and the doped metal source includes at least one of yttrium trichloride, cerium disulfide, scandium trichloride, thulium trichloride, and ytterbium trichloride.

[0018] Preferably, in step (2), the doped metal source includes yttrium trichloride.

[0019] As a preferred embodiment of the preparation method of the redox active solid electrolyte material of the present invention, in step (1), the mixing speed is 100rpm-200rpm and the time is 1h-3h; in the high-energy ball milling reaction, the ball-to-material ratio is (25-75):1 and the ball milling time is 12h-24h.

[0020] In a preferred embodiment of the preparation method of the redox active solid electrolyte material of the present invention, in step (2), the mixing speed is 100rpm-200rpm and the time is 1h-3h; the electrochemical treatment is to determine the lithium intercalation content in the positive electrode by controlling the discharge time of the full cell.

[0021] Thirdly, the present invention provides a composite cathode material, the composite cathode material comprising the redox active solid electrolyte, the cathode active material and the conductive agent.

[0022] As a preferred embodiment of the composite cathode material of the present invention, the cathode active material includes lithium cobalt oxide and / or lithium iron phosphate; and / or, the conductive agent includes conductive carbon black.

[0023] In a preferred embodiment of the composite cathode material of the present invention, the mass ratio of the redox active solid electrolyte, the cathode active material, and the conductive agent is (1-5):(4-8):1.

[0024] Preferably, the mass ratio of the redox active solid electrolyte, the positive electrode active material, and the conductive agent is 5:4:1.

[0025] Fourthly, the present invention provides an all-solid-state lithium battery, the all-solid-state lithium battery comprising a composite positive electrode layer, a solid electrolyte layer, a buffer layer and a negative electrode layer; the composite positive electrode layer comprising the aforementioned composite positive electrode material.

[0026] Compared with existing technologies, the beneficial effects of this invention are as follows: The redox-active solid-state electrolyte material of this invention, through the synergistic effect of multiple elements, significantly improves the room-temperature ionic conductivity of the material while maintaining structural stability, and also possesses suitable electronic conductivity, solving the key problems of slow ion transport kinetics and high interfacial charge transfer impedance in solid-state batteries. Secondly, the reversible capacity contributed by the redox-active solid-state electrolyte material of this invention, combined with the capacity of the positive electrode active material, creates a superposition effect, enabling the assembled all-solid-state lithium battery to achieve a higher overall specific capacity, directly improving the battery's energy density and overcoming the inherent defect of reduced energy density in traditional solid-state batteries due to the extensive use of inactive electrolytes. Furthermore, the redox-active solid-state electrolyte material of this invention possesses a high-speed dual-channel transport framework and a stable reaction interface. All-solid-state batteries based on this electrolyte exhibit excellent rate performance and ultra-long cycle stability, further demonstrating that this material possesses both high power output capability and long lifespan potential in practical devices, providing a highly competitive key material solution for the development of next-generation all-solid-state lithium batteries with high safety, high energy density, and high power. Attached Figure Description

[0027] Figure 1 shows the X-ray diffraction patterns of the redox-active solid electrolyte materials of Examples 1-4 and Comparative Example 1 of the present invention; Figure 2 shows the room temperature AC impedance spectra of the redox-active solid electrolyte materials of Examples 1-4 and Comparative Example 1 of the present invention; Figure 3 shows the charge-discharge curves of the all-solid-state lithium batteries of Example 2 and Comparative Example 1 of the present invention; Figure 4 shows the rate performance test of the all-solid-state lithium battery of Example 2 of the present invention; Figure 5 shows the long-term cycle performance test of the all-solid-state lithium battery of Example 2 of the present invention. Detailed Implementation

[0028] To better illustrate the objectives, technical solutions, and advantages of this invention, the invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0029] The following description, in conjunction with specific embodiments, illustrates the practical effects of the present invention.

[0030] Unless otherwise specified, the experimental methods used in the examples are conventional methods; the materials, reagents, equipment, etc. used are all commercially available unless otherwise specified.

[0031] Example 1: This example provides an all-solid-state lithium battery, the preparation method of which includes the following steps: S1, redox-active solid electrolyte material (chemical formula LiY) 0.5 Fe 0.5 Preparation of Cl4 (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar, and LiCl, FeCl3 and YCl3 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1. (2) First, the mixture is ball milled at 100rpm for 2h. Then, the speed is increased to 500rpm and a high-energy ball milling reaction is carried out for 15h to obtain redox active solid electrolyte material.

[0032] S2. Preparation of composite cathode material: In a glove box filled with argon gas (content 99.99%), weigh 50mg of positive electrode active material LiCoO2, 40mg of redox active solid electrolyte material and 10mg of conductive carbon SP, and manually grind and mix them in a mortar for more than 30 minutes to obtain a uniform composite cathode material.

[0033] S3, Battery Stacking: 80mg of solid electrolyte material (chemical formula Li) is placed in a 10mm diameter mold. 1.75 ZrO 0.5Cl4) is pressed at 1.5t for 2 min to form a dense electrolyte layer. Then, 10 mg of the composite positive electrode material prepared in step S2 is weighed and evenly spread on one side of the electrolyte layer, and pressed at 2t for 2 min to form a double-layer structure of positive electrode|electrolyte. To improve the interfacial stability between the electrolyte layer and the negative electrode, 40 mg of Li6PS5Cl powder is evenly spread on the other side of the electrolyte layer as a buffer layer, and pressed at 3 tons for 5 min.

[0034] S4. Negative Electrode Integration: A layer of Li-In alloy (5mg, lithium-indium mass ratio 1:1) is placed on the Li6PS5Cl buffer layer. The entire solid-state battery is placed in a stainless steel mold and a constant axial pressure of 100MPa is applied to assemble it into an all-solid-state lithium battery.

[0035] Example 2: This example provides an all-solid-state lithium battery, the preparation method of which includes the following steps: S1, redox-active solid electrolyte material (chemical formula Li 0.4 Y 0.7 Fe 0.5 Preparation of Cl4 (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar, and LiCl, FeCl3 and YCl3 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1. (2) First, the mixture is ball milled at 100rpm for 2h. Then, the speed is increased to 500rpm and a high-energy ball milling reaction is carried out for 15h to obtain redox active solid electrolyte material.

[0036] S2. Preparation of composite cathode material: In a glove box filled with argon gas (content 99.99%), weigh 50mg of positive electrode active material LiCoO2, 40mg of redox active solid electrolyte material and 10mg of conductive carbon SP, and manually grind and mix them in a mortar for more than 30 minutes to obtain a uniform composite cathode material.

[0037] S3, Battery Stacking: 80mg of solid electrolyte material (chemical formula Li) is placed in a 10mm diameter mold. 1.75 ZrO 0.5 Cl4) is pressed at 1.5t for 2 min to form a dense electrolyte layer. Then, 10 mg of the composite positive electrode material prepared in step S2 is weighed and evenly spread on one side of the electrolyte layer, and pressed at 2t for 2 min to form a double-layer structure of positive electrode|electrolyte. To improve the interfacial stability between the electrolyte layer and the negative electrode, 40 mg of Li6PS5Cl powder is evenly spread on the other side of the electrolyte layer as a buffer layer, and pressed at 3t for 5 min.

[0038] S4. Negative Electrode Integration: A layer of Li-In alloy (5mg, lithium-indium mass ratio 1:1) is placed on the Li6PS5Cl buffer layer. The entire solid-state battery is placed in a stainless steel mold and a constant axial pressure of 100MPa is applied to assemble it into an all-solid-state lithium battery.

[0039] Example 3: This example provides an all-solid-state lithium battery, the preparation method of which includes the following steps: S1, redox-active solid electrolyte material (chemical formula Li 0.1 Ce 0.25 Fe 1.05 S 0.4 Cl 3.2 Preparation of (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar, and LiCl, FeCl3 and CeS2 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1. (2) First, the mixture is ball milled at 100rpm for 2h. Then, the speed is increased to 500rpm and a high-energy ball milling reaction is carried out for 15h to obtain redox active solid electrolyte material.

[0040] S2. Preparation of composite cathode material: In a glove box filled with argon gas (content 99.99%), 50 mg of positive electrode active material LiCoO2, 40 mg of redox active solid electrolyte material and 10 mg of conductive carbon SP were weighed and manually ground and mixed in a mortar for more than 30 minutes to obtain a uniform all-solid-state battery composite cathode material.

[0041] S3, Battery Stacking: 80mg of solid electrolyte material (chemical formula Li) is placed in a 10mm diameter mold. 1.75 ZrO 0.5 Cl4) is pressed at 1.5t for 2 min to form a dense electrolyte layer. Then, 10 mg of the composite positive electrode material prepared in step S2 is weighed and evenly spread on one side of the electrolyte layer, and pressed at 2t for 2 min to form a double-layer structure of positive electrode|electrolyte. To improve the interfacial stability between the electrolyte layer and the negative electrode, 40 mg of Li6PS5Cl powder is evenly spread on the other side of the electrolyte layer as a buffer layer, and pressed at 3t for 5 min.

[0042] S4. Negative Electrode Integration: A layer of Li-In alloy (5mg, lithium-indium mass ratio 1:1) is placed on the Li6PS5Cl buffer layer. The entire solid-state battery is placed in a stainless steel mold and a constant axial pressure of 100MPa is applied to assemble it into an all-solid-state lithium battery.

[0043] Example 4: This example provides an all-solid-state lithium battery, the preparation method of which includes the following steps: S1, redox-active solid electrolyte material (chemical formula Li 0.1 Sc 0.25 Fe 1.05 (OH) 0.1 Cl 3.9 Preparation of ) (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar, and LiOH, FeCl3 and ScCl3 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1. (2) First, the mixture is ball milled at 100rpm for 2h. Then, the speed is increased to 500rpm and a high-energy ball milling reaction is carried out for 15h to obtain redox active solid electrolyte material.

[0044] S2. Preparation of composite cathode material: In a glove box filled with argon gas (content 99.99%), 50 mg of positive electrode active material LiCoO2, 40 mg of redox active solid electrolyte material and 10 mg of conductive carbon SP were weighed and manually ground and mixed in a mortar for more than 30 minutes to obtain a uniform all-solid-state battery composite cathode material.

[0045] S3, Battery Stacking: 80mg of solid electrolyte material (chemical formula Li) is placed in a 10mm diameter mold. 1.75 ZrO 0.5 Cl4) is pressed at 1.5t for 2 min to form a dense electrolyte layer. Then, 10 mg of the composite positive electrode material prepared in step S2 is weighed and evenly spread on one side of the electrolyte layer, and pressed at 2t for 2 min to form a double-layer structure of positive electrode|electrolyte. To improve the interfacial stability between the electrolyte layer and the negative electrode, 40 mg of Li6PS5Cl powder is evenly spread on the other side of the electrolyte layer as a buffer layer, and pressed at 3t for 5 min.

[0046] S4. Negative Electrode Integration: A layer of Li-In alloy (5mg, lithium-indium mass ratio 1:1) is placed on the Li6PS5Cl buffer layer. The entire solid-state battery is placed in a stainless steel mold and a constant axial pressure of 100MPa is applied to assemble it into an all-solid-state lithium battery.

[0047] Example 5: This example provides an all-solid-state lithium battery. The only difference between its preparation method and Example 2 is that in step S1, the preparation method of the redox-active solid electrolyte material includes the following steps: S1, redox-active solid electrolyte material (chemical formula Li 0.7 Y 0.7 Fe 0.4Preparation of Cl4 (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar, and LiCl, FeCl3 and YCl3 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1. (2) First, the mixture is ball milled at 100rpm for 2h. Then, the speed is increased to 500rpm and a high-energy ball milling reaction is carried out for 15h to obtain redox active solid electrolyte material.

[0048] Example 6: This example provides an all-solid-state lithium battery. The only difference between its preparation method and Example 2 is that in step S1, the preparation method of the redox-active solid electrolyte material includes the following steps: S1, redox-active solid electrolyte material (chemical formula Li 0.1 Y 0.7 Fe 0.6 Preparation of Cl4 (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar, and LiCl, FeCl3 and YCl3 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1. (2) First, the mixture is ball milled at 100rpm for 2h. Then, the speed is increased to 500rpm and a high-energy ball milling reaction is carried out for 15h to obtain redox active solid electrolyte material.

[0049] Example 7: This example provides an all-solid-state lithium battery. The only difference between its preparation method and Example 2 is that in step S1, the preparation method of the redox-active solid electrolyte material includes the following steps: S1, redox-active solid electrolyte material (chemical formula Li 0.4 Tm 0.7 Fe 0.5 Preparation of Cl4 (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar. LiCl, FeCl3 and TmCl3 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1. (2) First, the mixture is ball milled at 100rpm for 2h. Then, the speed is increased to 500rpm and a high-energy ball milling reaction is carried out for 15h to obtain redox active solid electrolyte material.

[0050] Example 8: This example provides an all-solid-state lithium battery. The only difference between its preparation method and Example 2 is that in step S1, the preparation method of the redox-active solid electrolyte material includes the following steps: S1, redox-active solid electrolyte material (chemical formula Li 0.4 Yb 0.7 Fe 0.5Preparation of Cl4 (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar, and LiCl, FeCl3 and YbCl3 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1. (2) First, the mixture is ball milled at 100rpm for 2h. Then, the speed is increased to 500rpm and a high-energy ball milling reaction is carried out for 15h to obtain redox active solid electrolyte material.

[0051] Example 9: This example provides an all-solid-state lithium battery. The only difference between its preparation method and Example 2 is that in step S1, the preparation method of the redox-active solid electrolyte material includes the following steps: S1, redox-active solid electrolyte material (chemical formula Li 0.4 Y 0.8 Fe 0.4 Preparation of Cl4 (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar, and LiCl, FeCl3 and YCl3 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1. (2) First, the mixture is ball milled at 100rpm for 2h. Then, the speed is increased to 500rpm and a high-energy ball milling reaction is carried out for 15h to obtain redox active solid electrolyte material.

[0052] Example 10: This example provides an all-solid-state lithium battery. The only difference between its preparation method and Example 2 is that in step S1, the preparation method of the redox-active solid electrolyte material includes the following steps: S1, redox-active solid electrolyte material (chemical formula Li 0.4 Y 0.6 Fe 0.6 Preparation of Cl4 (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar, and LiCl, FeCl3 and YCl3 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1. (2) First, the mixture is ball milled at 100rpm for 2h. Then, the speed is increased to 500rpm and a high-energy ball milling reaction is carried out for 15h to obtain redox active solid electrolyte material.

[0053] Comparative Example 1: This comparative example provides an all-solid-state lithium battery. The difference between its preparation method and Example 2 is only that: in step S1, the preparation method of the redox active solid electrolyte material includes the following steps: S1, preparation of redox active solid electrolyte material (chemical formula LiFeCl4) (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar, and LiCl and FeCl3 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1; (2) First, the mixture is ball milled at a speed of 100rpm for 2h. Then, the speed is increased to 500rpm and a high-energy ball milling reaction is carried out for 15h to obtain the redox active solid electrolyte material.

[0054] Comparative Example 2: This comparative example provides an all-solid-state lithium battery, the only difference between its preparation method and Example 2 is that: in step S1, the preparation method of the redox-active solid electrolyte material includes the following steps: S1, redox-active solid electrolyte material (chemical formula Li 0.7 Fe 1.1 Preparation of Cl4) (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar, and LiCl and FeCl3 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1. (2) After ball milling and mixing at 100rpm for 2h, the speed is increased to 500rpm and high-energy ball milling reaction is carried out for 15h to obtain the redox active solid electrolyte material.

[0055] Comparative Example 3: This comparative example provides an all-solid-state lithium battery. The difference between its preparation method and Example 2 is only that: in step S1, the preparation method of the redox active solid electrolyte material includes the following steps: S1, preparation of redox active solid electrolyte material (chemical formula Li2ZrOCl4) (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar, and Li2O and ZrCl4 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1; (2) First, the mixture is ball milled at 100rpm for 2h, and then the speed is increased to 500rpm for a high-energy ball milling reaction for 15h to obtain the redox active solid electrolyte material.

[0056] Comparative Example 4: This comparative example provides an all-solid-state lithium battery, the only difference between its preparation method and Example 2 is that: in step S1, the preparation method of the redox-active solid electrolyte material includes the following steps: S1, redox-active solid electrolyte material (chemical formula Li 0.4 In0.7 Fe 0.5 Preparation of Cl4) (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar, and LiCl, FeCl3 and InCl3 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1. (2) First, the mixture is ball milled at 100rpm for 2h. Then, the speed is increased to 500rpm and a high-energy ball milling reaction is carried out for 15h to obtain redox active solid electrolyte material.

[0057] Comparative Example 5: This comparative example provides an all-solid-state lithium battery, the only difference between its preparation method and Example 2 is that: in step S1, the preparation method of the redox-active solid electrolyte material includes the following steps: S1, redox-active solid electrolyte material (chemical formula Li 1.3 Y 0.7 Fe 0.2 Preparation of Cl4 (1) Under the protection of argon atmosphere, the water and oxygen content in the glove box is controlled to be less than 0.01ppm. 75g of ball milling beads are added to a 50mL ball milling jar, and LiCl, FeCl3 and YCl3 are weighed as raw materials according to the stoichiometric ratio and placed in the ball milling jar. The ball-to-material ratio is controlled to be 50:1. (2) First, the mixture is ball milled at 100rpm for 2h. Then, the speed is increased to 500rpm and a high-energy ball milling reaction is carried out for 15h to obtain redox active solid electrolyte material.

[0058] Test Example: 1.1, Structural and Morphological Characterization Test Method: X-ray diffraction (XRD) tests were performed on the redox active solid electrolyte materials prepared in step S1 of Examples 1-4 and Comparative Example 1, respectively.

[0059] As shown in Figure 1, the diffraction peaks of the redox active solid electrolyte materials in Examples 1-4 of this invention all match the characteristic peaks of the crystal structure of FeCl3, indicating that the doping modification of this invention did not change its main crystal structure and did not generate impurity phases.

[0060] 1.2 Ionic and electronic conductivity test method: 150 mg of the redox active solid electrolyte material prepared in step S1 of Examples 1-10 and Comparative Examples 1-5 were placed in a mold and pressed into an electrolyte sheet under a pressure of 500 MPa. Then, they were assembled into Ti|electrolyte|Ti symmetric cells and tested using an electrochemical workstation.

[0061] Ionic conductivity: The room temperature ionic conductivity was calculated by measuring the AC impedance spectrum (frequency range set to 7 MHz-1 Hz, amplitude 100mV) using the AC impedance method. The results are shown in Table 1 and Figure 2.

[0062] As shown in Figure 2, the redox active solid electrolyte materials of Examples 1-4 of the present invention can significantly improve their room temperature ionic conductivity by doping FeCl3, and the room temperature ionic conductivity is greater than 4.0 mS / cm, indicating that the redox active solid electrolyte of the present invention has excellent ion transport capability.

[0063] Electronic conductivity: The electronic conductivity was calculated by measuring the steady-state current using the DC polarization method (test voltage 0.1V-0.5V, continuous for 2h), and the results are shown in Table 1.

[0064] 1.3 Electrochemical Performance Testing 1.3.1 Half-Cell Specific Capacity Testing Test Method: In a glove box filled with argon gas (99.99% purity), weigh 50 mg of the positive electrode active material LiCoO2, 40 mg of the redox active solid electrolyte material prepared in step S1 of Examples 1-10 or Comparative Examples 1-5, and 10 mg of conductive carbon SP. After mixing, plasma ball milling was performed for at least 30 minutes to obtain a uniform half-cell composite positive electrode material. The half-cell composite positive electrode material was assembled into a half-cell with lithium metal as the counter electrode and the solid electrolyte layer and composite positive electrode as the working electrode.

[0065] The Blue Battery testing system was used, operating at a constant temperature of 25°C and within a voltage window of 2.0V-3.6V, at a current of 0.127mA / cm. 2 The constant current charge-discharge test was performed using the current density, and the resulting capacity is the capacity contributed by the variable valence cation. The results are shown in Table 1.

[0066] 1.3.2 Full Cell Specific Capacity Test Method: The Blue Battery testing system was used, operating at a constant temperature of 25°C within a voltage window of 2.0V-3.6V, at a rate of 0.127mA / cm². 2 The current density was used to perform constant current charge-discharge tests on the all-solid-state lithium batteries prepared in step S4 of Examples 1-10 and Comparative Examples 1-5. The obtained capacity is the specific capacity of the full cell. The results are shown in Table 1 and Figure 3.

[0067] As shown in Figure 3, the all-solid-state lithium battery of Embodiment 2 of the present invention uses an electrolyte with redox activity as the electrolyte material in the composite cathode, which can contribute an additional 86.1 mAh / g of specific capacity, greatly improving the energy density of the all-solid-state lithium battery.

[0068] 1.3.3 Full Battery Rate Performance Test Method: Using the Blue Battery Testing System, at a constant temperature of 25°C and within a voltage window of 2.0V-3.6V, the all-solid-state lithium battery prepared in step S4 of Example 2 was first tested at a low rate (0.1C, 0.127mA / cm). 2Five charge-discharge cycles were performed. Then, within the same voltage window, constant current charge-discharge tests were conducted with a step-increase-then-decrease current density (0.2C, 0.3C, 0.5C, 1C, 0.1C) to obtain the rate performance of the full battery. The results are shown in Figure 4.

[0069] As shown in Figure 4, the all-solid-state lithium battery of Embodiment 2 of the present invention has excellent rate performance. Even at a high rate of 1C, it still has a reversible capacity of 136mAh / g, indicating that it has extremely fast ion / electron transport kinetics and excellent rate performance. Moreover, when the current density returns to 0.1C, the capacity almost recovers to the initial value, indicating that the battery structure remains intact after a high rate shock and no irreversible damage occurs.

[0070] 1.3.4. Full-cell long-cycle stability test method: The Blue Battery testing system was used. At a constant temperature of 25°C and a voltage window of 2.0V-3.6V, the all-solid-state lithium battery prepared in step S4 of Example 2 was tested at a fixed current density (1C, 1.27mA / cm²). 2 At least 500 consecutive constant current charge-discharge cycles were performed, and the discharge specific capacity and coulombic efficiency of each cycle were recorded. The results are shown in Figure 5.

[0071] As shown in Figure 5, the all-solid-state lithium battery of Embodiment 2 of the present invention shows almost no capacity decay after 500 cycles, indicating that the all-solid-state lithium battery has excellent cycle stability.

[0072] Table 1 Performance test results of redox-active solid electrolyte materials and all-solid-state lithium batteries in the test examples of this invention. The test results in Table 1 and Figures 1-5 show that the redox-active solid electrolyte material of this invention possesses high ionic and electronic conductivity, as well as intrinsic redox activity. It breaks through the passive role of traditional solid electrolytes as merely "ionic conductors," enabling them to function as active materials, working synergistically with the cathode material to contribute to capacity, thereby significantly improving the energy density and interface stability of the full battery. Specifically, the redox-active solid electrolyte material of this invention, through doping with rare earth or variable-valence elements, significantly improves the room-temperature ionic and electronic conductivity of the solid electrolyte. For example, the ionic conductivity of Example 2 reaches 9.65 × 10⁻⁶. -3 S / cm, Comparison Example 1 (4.63×10 -6The S / cm ratio is nearly three orders of magnitude higher. Secondly, the redox-active solid electrolyte material of this invention can undergo redox reactions during charge and discharge, providing excellent variable-valence cation contribution capacity (52.5 mAh / g-86.1 mAh / g). This characteristic allows the solid electrolyte material of this invention not only to act as an ion conductor but also to become a component of the positive electrode capacity, thereby significantly improving the overall capacity of the full battery. The contribution capacity of Comparative Examples 1-5 is significantly lower than that of this invention. Furthermore, the redox-active solid electrolyte material of this invention also achieves extremely high full-cell specific capacity (up to 220.1 mAh / g), excellent rate performance, and long-cycle stability.

[0073] Therefore, the solid electrolyte material of this invention, which combines high ionic conductivity, moderate electronic conductivity, and significant redox activity, exhibits significant advantages in improving the energy density, rate performance, and cycle stability of all-solid-state batteries. Furthermore, all-solid-state batteries assembled based on the electrolyte material of this invention demonstrate high efficiency, long cycle life, and excellent rate performance, fully verifying its enormous application potential in practical solid-state battery devices and providing a competitive electrolyte solution for the development of next-generation high-safety, high-energy-density solid-state batteries.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A redox-active solid electrolyte material, characterized in that, The chemical formula of the redox-active solid electrolyte material is Li x Fe y M z B m Cl n Wherein, the values ​​of x, y, z, m, and n satisfy 0.01≤x≤1, 0.1≤y<1.4, 0≤z<1.4, 0≤m≤4, and 0<n≤4; M includes at least one of La, Sc, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y, Yb, and Lu; and B includes at least one of O, S, Se, N, OH, NO3, PO4, and SO4.

2. The redox-active solid electrolyte material as described in claim 1, characterized in that, The M includes at least one of Sc, Ce, Y, Tm, and Yb; and / or the B includes at least one of O, S, and OH.

3. The redox-active solid electrolyte material as described in claim 2, characterized in that, M includes Y.

4. The redox-active solid electrolyte material as described in claim 1, characterized in that, The values ​​of x, y, and z satisfy 0.01≤x≤0.7, 0.4≤y≤1.05, and 0.25≤z≤0.

8.

5. The redox-active solid electrolyte material as described in claim 4, characterized in that, The values ​​of x, y, and z satisfy 0.1≤x≤0.4, 0.5≤y≤0.6, and 0.5≤z≤0.

7.

6. The method for preparing the redox-active solid electrolyte material as described in claim 1, characterized in that, Choose any one of the following (1)-(2): (1) Under a protective atmosphere, mix lithium source, iron source and doped metal source in stoichiometric ratio and perform high-energy ball milling reaction to obtain the redox active solid electrolyte material; (2) Under a protective atmosphere, mix iron source and doped metal source as positive electrode, lithium source as solid electrolyte, and lithium indium alloy as negative electrode, assemble into a full cell and perform electrochemical treatment to obtain the redox active solid electrolyte material.

7. The method for preparing the redox-active solid electrolyte material as described in claim 6, characterized in that, In step (1), the lithium source includes at least one of lithium hydroxide, lithium oxide, lithium chloride, lithium carbonate, lithium phosphate, lithium sulfate, and lithium nitrate; the iron source includes ferric chloride; the doped metal source includes at least one of yttrium trichloride, cerium disulfide, scandium trichloride, thulium trichloride, and ytterbium trichloride; and / or, in step (2), the lithium source includes lithium zirconium chloride oxychloride; the iron source includes ferric chloride; the iron source includes ferric chloride; the doped metal source includes at least one of yttrium trichloride, cerium disulfide, scandium trichloride, thulium trichloride, and ytterbium trichloride.

8. A composite cathode material, characterized in that, It includes the redox active solid electrolyte material, positive electrode active material, and conductive agent as described in any one of claims 1-5.

9. The composite cathode material as described in claim 8, characterized in that, The positive electrode active material includes lithium cobalt oxide and / or lithium iron phosphate; and / or, the conductive agent includes conductive carbon black.

10. An all-solid-state lithium battery, characterized in that, It includes a composite positive electrode layer, a solid electrolyte layer, a buffer layer, and a negative electrode layer; the composite positive electrode layer includes the composite positive electrode material as described in claim 8 or 9.

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