Flexible high ionic conductive inorganic solid electrolyte, and preparation method and application thereof

Abstract

This invention discloses a flexible, highly ion-conducting inorganic solid electrolyte, its preparation method, and its applications, relating to the field of electrolyte materials technology. The general chemical formula is [chemical formula not provided]. x Li2O-Ga 1‑y M y Cl 3‑z X z , 0.3≤ x ≤2.2, 0≤ y ≤1, 0≤ z ≤3. The flexible solid electrolyte material of this invention can achieve high densification under low stacking pressure of approximately 30~100 MPa, exhibiting a high room temperature ionic conductivity of 0.2~1 mS / cm, a Young's modulus of 0.5~2 GPa, and good mechanical plasticity. The flexible solid electrolyte of this invention not only possesses a low Young's modulus and high ionic conductivity but also a wide electrochemical stability window. When matched with a high-voltage cathode and applied to the cathode side of an all-solid-state battery, the solid electrolyte provides stability to the cathode, resulting in an all-solid-state battery with excellent electrochemical performance and promising application prospects.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage technology, specifically relating to flexible high ion conductivity inorganic solid electrolyte materials, their preparation methods, and their applications in solid-state batteries. Background Technology

[0002] Commercially available rechargeable batteries mostly use flammable organic electrolytes, posing safety hazards such as electrolyte leakage and thermal runaway. Furthermore, their electrochemical stability window is generally below 4.5 V, making it difficult to match them with high-voltage cathode materials. All-solid-state batteries, using intrinsically safe solid electrolytes, can significantly improve safety and energy density, and are considered an important development direction for next-generation energy storage technology, possessing significant application value in key areas such as power batteries and aerospace.

[0003] As a core component, the ion transport characteristics and mechanical properties of solid electrolytes directly determine the electrochemical performance of batteries. An ideal solid electrolyte should possess high room-temperature ionic conductivity, a wide electrochemical stability window, and good flexibility and ductility. Existing solid electrolyte systems each have their advantages, but it is difficult to simultaneously achieve interfacial stability, ionic conductivity, and mechanical properties. Although polymer electrolytes have good flexibility (Young's modulus is usually less than 10 GPa), their room-temperature ionic conductivity is low, and their electrochemical window is narrow.

[0004] In contrast, inorganic solid electrolytes typically exhibit higher ionic conductivity, wider electrochemical stability windows, and superior electrochemical stability. However, current inorganic solid electrolyte materials suffer from high mechanical brittleness and poor flexibility, leading to poor contact between solid electrolyte particles and at the solid electrolyte / electrode interface. This necessitates high stacking pressure (~250 MPa) to mitigate solid-solid interface failure. Furthermore, their room-temperature ionic conductivity and electrochemical window still require improvement, hindering the application of high-energy-density solid-state batteries and the demand for room-temperature operation. Therefore, there is an urgent need to provide a solid electrolyte that maintains high flexibility at room temperature while still exhibiting high ionic conductivity and a wide electrochemical stability window, achieving high electrolyte layer density and tight electrode / electrolyte interface contact without requiring high stacking pressure. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing solid-state electrolytes by providing a flexible, highly ion-conducting inorganic solid-state electrolyte, its doping method, and its applications. This solves the problems of low room-temperature ion conductivity, insufficient high-voltage stability, and poor mechanical flexibility in current inorganic solid-state electrolytes. A highly ion-conducting inorganic electrolyte material with good flexibility has been developed, which can achieve high electrolyte layer density and tight electrode / electrolyte interface contact in all-solid-state battery systems without high stacking pressure. It is not only suitable for high-voltage solid-state lithium battery systems but also for sodium, potassium, and other alkali metal battery systems, exhibiting excellent electrochemical performance.

[0006] To achieve the above objectives, the following technical solution is proposed: Firstly, a flexible, highly ion-conducting inorganic solid electrolyte is provided, with the following general chemical formula: x Li2O-Ga 1-y M y Cl 3- z X z ; Where M is a cation dopant and X is an anion dopant, 0.3≤ x ≤2.2, 0≤ y ≤1, 0≤ z ≤3, and y = z =0 indicates an undoped solid electrolyte.

[0007] This invention provides a flexible, highly ion-conducting inorganic solid electrolyte. The coexistence structure of Li2O and GaX3 in the solid electrolyte and their interphase interaction not only enhance the ion transport capability but also improve the mechanical flexibility of the solid electrolyte, thus exhibiting good plasticity. This allows for the high densification of the electrolyte layer and close solid-solid interface contact in the all-solid battery system under low stacking pressure.

[0008] Preferably, the solid electrolyte is a cation-doped and / or anion-doped solid electrolyte; The cation M is selected from one or more elements chosen from Ti, Zr, Hf, V, Nb, Ta, Sc, Y, Al, In, P, Sb, Mg, Ca, Sr, Ba, Si, Ge, La, Sm, Tb, Ho, Gd, and Er; the anion X is selected from one or more elements chosen from F, Br, I, N, S, and Se. Cation doping or co-doping of cations and anions yields doped solid electrolytes to further optimize the ionic conductivity, electrochemical stability window, and mechanical plasticity of the solid electrolyte.

[0009] Preferably, 0 < y ≤0.4, such as 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, etc., 0 < z ≤2, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, etc.

[0010] Preferably, the solid electrolyte is clay-like, and its Young's modulus is 0.5~2 GPa, such as 0.5GPa, 0.8GPa, 1GPa, 1.2GPa, 1.5GPa, 1.8GPa, 2.0GPa, etc.

[0011] Preferably, the room temperature ionic conductivity of the cold-pressed sheet obtained by the solid electrolyte under a stacking pressure of 30~100 MPa is 0.2~1 mS / cm, for example 0.2 mS / cm, 0.3 mS / cm, 0.4 mS / cm, 0.5 mS / cm, 0.6 mS / cm, 0.7 mS / cm, 0.8 mS / cm, 0.9 mS / cm, 1.0 mS / cm, etc.

[0012] This invention provides a method for preparing a flexible, highly ion-conducting inorganic solid electrolyte. The method for preparing the solid electrolyte material includes the following steps: under an inert atmosphere, raw materials required for preparing the solid electrolyte are weighed according to a certain stoichiometric ratio, including lithium source, gallium source, oxygen source, chlorine source and optional doping source, and ground and mixed evenly to obtain an electrolyte matrix mixed powder; subsequently, a high-energy ball milling method is used to prepare the solid electrolyte material to obtain the inorganic solid electrolyte.

[0013] Preferably, in the preparation method, the high-energy ball milling speed is 200~1000 rpm, such as 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, etc., the mass ratio of the ball milling beads to the electrolyte matrix mixed powder is 20:1~100:1, such as 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, etc., and the ball milling time is 3~60 h.

[0014] More preferably, the ball milling speed is 300~800 rpm, the mass ratio of the ball milling beads to the electrolyte matrix mixed powder is 20:1~80:1, and the ball milling time is 5~50 h.

[0015] Preferably, the lithium source is Li2O; the gallium source is selected from one or more of GaCl3, GaBr3, GaF3, Ga2O3, Ga(OH)3, Ga(NO3)3, Ga2(CO3)3, Ga2(SO4)3, GaOF, GaOCl, and GaOBr; the oxygen source and chlorine source are selected from one or more of the lithium source, gallium source, and doping source. The doping source is an anion doping source or a cation doping source; The anion doping source is selected from one or more of LiF, LiBr, LiI, Li2S, Li3N, Li2Se, Li2S, GaF3, GaBr3, GaI3, GaN, Ga2Se3, and Ga2S3; The cation doping source is selected from MF. α ,MClα , MBr α MI α MN α MSe α MS α MO α One or more of them.

[0016] Preferably, the molar ratio of lithium in the lithium source to gallium in the gallium source is 0.6 to 4.4, for example, 0.6, 0.8, 1, 1.2, 1.5, 1.8, 2.0, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4.0, 4.2, 4.4, etc.

[0017] Preferably, the molar ratio of lithium in the lithium source to oxygen in the oxygen source is 0.4 to 2, for example, 0.4, 0.6, 0.8, 1, 1.2, 1.5, 1.8, 2.0, etc.

[0018] Preferably, the molar ratio of gallium in the gallium source to chlorine in the chlorine source is 0.3 to 2, for example, 0.3, 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2.0, etc.

[0019] Preferably, the molar ratio of gallium in the gallium source to cation in the cation-doped source is 1.5 to 9, for example, 1.5, 1.8, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.2, 8.5, 8.8, 9, etc.

[0020] Preferably, the molar ratio of chlorine in the chlorine source to anion in the anion dopant source is 0.5 to 59, for example, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 42, 45, 48, 50, 52, 55, 59, etc.

[0021] Furthermore, the present invention provides a solid-state alkali metal battery, comprising the aforementioned flexible inorganic solid electrolyte with high ionic conductivity or the aforementioned flexible inorganic solid electrolyte with high ionic conductivity prepared by the aforementioned preparation method.

[0022] Preferably, the solid alkali metal battery includes a positive electrode, a negative electrode, and an electrolyte layer located between the positive electrode and the negative electrode, wherein at least one of the positive electrode, the negative electrode, and the electrolyte layer contains the solid electrolyte material.

[0023] Compared with the prior art, the present invention has the following beneficial effects: The solid electrolyte in this invention maintains high flexibility while exhibiting high ionic conductivity and a wide electrochemical stability window. All-solid-state batteries assembled based on this solid electrolyte demonstrate good interfacial contact, exhibiting high discharge specific capacity, good cycle stability, and rate performance while maintaining high voltage stability. Furthermore, the battery fabrication method using this electrolyte is simple, and the electrochemical performance is excellent, showing broad application prospects and advantages.

[0024] This invention discloses a flexible, highly ionicly conductive inorganic solid electrolyte. Compared with existing technologies, the advantages of this invention include: Firstly, the preparation method used in this invention is a common method for preparing inorganic solid electrolytes, based on mechanochemistry and solid-phase reactions. The process is simple, reproducible, and produces a product with uniform composition, facilitating large-scale production. Secondly, this invention provides a flexible, highly ionicly conductive inorganic solid electrolyte with the following chemical formula: x Li2O-Ga 1-y M y Cl 3-z X z This invention eliminates the need for secondary composite preparation using other types of electrolytes (such as polymer electrolytes), framework materials (such as MOF, COF), or organic binders (such as PTFE) to enhance mechanical plasticity. By utilizing only the interaction between O and X elements in the system, the inorganic solid electrolyte exhibits excellent mechanical flexibility and plasticity, fulfilling the superior mechanical performance requirements of electrolytes in solid-state batteries. Specifically, under cold pressing conditions, the electrolyte of this invention only requires 30 MPa to achieve electrolyte ionic conductivity saturation, while existing inorganic electrolytes require at least 250 MPa. This not only allows for the simple preparation of dense ceramic electrolytes but also enables excellent solid-solid interface contact in solid-state batteries. Furthermore, the solid electrolyte provided by this invention possesses an ionic conductivity as high as 1 S / cm, enabling rapid ion transport in solid-state batteries. Simultaneously, this solid electrolyte exhibits a wide electrochemical stability window, particularly compatible with high-voltage cathodes. The assembled solid-state battery maintains excellent electrochemical performance even when charged to 4.8 V. This wide electrochemical window characteristic is unattainable by most current electrolytes. The solid electrolyte prepared by this invention exhibits excellent performance in terms of ionic conductivity, electrochemical stability window, and mechanical properties. It is not only suitable for high-voltage solid-state lithium battery systems, but also for alkali metal battery systems such as sodium and potassium. Furthermore, solid-state batteries assembled based on this electrolyte demonstrate excellent performance. Attached Figure Description

[0025] Figure 1 This is the electrochemical impedance spectroscopy of the solid electrolyte prepared in Example 1 of this invention.

[0026] Figure 2 The X-ray diffraction patterns are those of the solid electrolytes prepared in Examples 1 and 2 of this invention.

[0027] Figure 3 The all-solid-state battery assembled with the solid electrolyte prepared in Example 1 of this invention and NMC-83 at 2.6-4.8V vs Li + Initial charge-discharge curves within the / Li voltage range. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments and accompanying drawings, but the present invention is not limited to the following embodiments. Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of the present invention.

[0029] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0030] Example 1 Preparation of solid electrolyte: Li2O:GaCl3 was loaded into an inert atmosphere-filled ball mill jar in a glove box with water and oxygen contents both below 0.1 ppm at a molar ratio of 0.5:1. The ball-to-material ratio was 20:1, and the rotation speed was 500 rpm to obtain the solid electrolyte material of sample 1.

[0031] Ion conductivity testing: In a glove box where both water and oxygen content were below 0.1 ppm, 100 mg of the solid electrolyte material from sample 1 was weighed and placed inside a standard molded battery with a diameter of 10 mm. A pressure of approximately 60 MPa was applied and maintained for 3 minutes to obtain a solid electrolyte sheet. The battery was then assembled, and its electrochemical impedance spectroscopy was tested. The ionic conductivity of sample 1 at room temperature was determined to be 0.3 mS / cm. Figure 1 As shown.

[0032] X-ray diffraction test: The solid electrolyte was sealed in an inert atmosphere, and the X-ray diffraction pattern of the solid electrolyte was measured at 10°~80° using a Cu-Kα X-ray source, as shown in the figure. Figure 2 As shown.

[0033] Young's modulus test: The test was conducted using nanoindentation. The sample was a cold-pressed solid electrolyte sheet (10 mm in diameter), with a loading force of 10 mN, and an Oliver... The Pharr method is used to calculate the elastic modulus, and the Young's modulus is approximately 0.5 GPa.

[0034] Battery Assembly: In a glove box with water and oxygen content both below 0.1 ppm, the solid electrolyte material of Sample 1 and NMC83 (as the positive electrode active material) were mixed at a mass ratio of 30:70 to prepare a positive electrode mixture. 100 mg of Li6PS5Cl solid electrolyte, 100 mg of Sample 1 solid electrolyte, and 10 mg of the positive electrode mixture were sequentially stacked to form a laminate. A pressure of 300 MPa was applied to the laminate to form the solid electrolyte and positive electrode layers. Then, a 200 μm layer of Li-In alloy was stacked on one side of the Li6PS5Cl solid electrolyte to obtain the laminate. This laminate was then assembled into a molded battery for electrochemical performance testing. Charge-discharge tests were conducted at 0.2 C at room temperature, with a test voltage range of 2.8–4.8 V vs Li + / Li, the initial discharge specific capacity is 195 mAh / g, such as Figure 3 As shown.

[0035] Example 2 The solid electrolyte material of sample 2 was prepared using the same method as sample 1 with a Li₂O:GaCl₃ molar ratio of 1:1. The testing methods for sample 2 were the same as those for sample 1, including electrochemical impedance spectroscopy, Young's modulus, X-ray diffraction, and electrochemical performance testing. The ionic conductance of sample 2 at room temperature was 0.55 mS / cm, and the Young's modulus was approximately 0.5 GPa.

[0036] Example 3 The solid electrolyte material of sample 4 was prepared using the same method as sample 1, with a Li₂O:GaCl₃ molar ratio of 1.5:1. The testing methods for sample 3 were the same as for sample 1, including electrochemical impedance spectroscopy, Young's modulus, X-ray diffraction, and electrochemical performance testing. Sample 3 exhibited an ionic conductivity of 0.7 mS / cm and a Young's modulus of approximately 0.7 GPa at room temperature.

[0037] Example 4 Preparation of solid electrolyte: Li₂O and GaCl₃ were loaded into an inert atmosphere-filled ball mill jar at a molar ratio of 0.5:1 in a glove box with both water and oxygen content below 0.1 ppm. The ball-to-material ratio was 20:1, and the milling speed was 800 rpm, yielding the solid electrolyte material of sample 4. The testing methods for sample 4 were the same as for sample 1, including ionic conductivity, Young's modulus, X-ray diffraction, and electrochemical performance testing. Sample 4 exhibited an ionic conductivity of 0.8 mS / cm and a Young's modulus of approximately 0.5 GPa at room temperature.

[0038] Example 5 The solid electrolyte material of sample 5 was prepared using the same method as sample 4, with a Li₂O:GaCl₃ molar ratio of 2:1. The testing methods for sample 5 were the same as for sample 1, including ionic conductivity, Young's modulus, X-ray diffraction, and electrochemical performance testing. Sample 5 had an ionic conductivity of 0.8 mS / cm and a Young's modulus of approximately 0.6 GPa at room temperature.

[0039] Example 6 Preparation of solid electrolyte: Li₂O:GaCl₃ was loaded into an inert atmosphere-filled ball mill jar at a molar ratio of 2:1 in a glove box with both water and oxygen content below 0.1 ppm. The ball-to-material ratio was 20:1, and the milling speed was 800 rpm. After 30 h, the solid electrolyte material of sample 6 was obtained. The testing methods for sample 6 were the same as those for sample 1, including ionic conductivity, Young's modulus, X-ray diffraction, and electrochemical performance testing. The ionic conductivity of sample 6 at room temperature was 0.5 mS / cm, and the Young's modulus was approximately 1.8 GPa.

[0040] Example 7 The solid electrolyte material for sample 7 was prepared using the same method as for sample 6, with a molar ratio of Li₂O:GaF₃:TaCl₅ of 0.5:1:0.5. The testing methods for sample 7 were the same as for sample 1, including ionic conductivity, Young's modulus, X-ray diffraction, and electrochemical performance testing. Sample 7 exhibited an ionic conductivity of 1.0 mS / cm and a Young's modulus of approximately 0.6 GPa at room temperature.

[0041] Comparative Example 1 The solid electrolyte of Example 1 was used to test the ionic conductivity. The electrolyte material processing steps were the same as in Example 1, except that pressures of about 30 and 100 MPa were applied and held for 3 min to obtain solid electrolyte sheets formed under different stacking pressures. Using the same test method as in Example 1, the ionic conductivity of Comparative Example 1 at room temperature was 0.3 mS / cm under stacking pressures of 30 and 100 MPa.

[0042] Comparative Example 2 The solid electrolyte of Example 6 was used to test the ionic conductivity. The electrolyte material processing steps were the same as those of Comparative Example 1. Solid electrolyte sheets were obtained under different stacking pressures. Using the same test method as Example 1, the ionic conductivity of Comparative Example 1 at room temperature was 0.45 and 0.5 mS / cm at stacking pressures of 30 and 100 MPa, respectively.

[0043] Table 1. Pressure conditions and results for testing Young's modulus and room temperature ionic conductivity of solid electrolytes. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A flexible high-ionic-conductivity inorganic solid electrolyte, characterized by, The chemical general formula of the solid electrolyte is: x Li2O-Ga 1-y M y Cl 3-z X z ; where M is a cationic doping element, X is an anionic doping element, 0.3≤ x ≤2.2, 0≤ y ≤1, 0≤ z ≤3, and y = z = 0 is an undoped solid electrolyte.

2. The flexible high-ionic-conductivity inorganic solid electrolyte according to claim 1, wherein The solid electrolyte is a cation-doped and / or anion-doped solid electrolyte; The cation M is selected from one or more elements chosen from Ti, Zr, Hf, V, Nb, Ta, Sc, Y, Al, In, P, Sb, Mg, Ca, Sr, Ba, Si, Ge, La, Sm, Tb, Ho, Gd, and Er; the anion X is selected from one or more elements chosen from F, Br, I, N, S, and Se; where 0 < y ≤0.4, 0< z ≤2.

3. The flexible inorganic solid electrolyte with high ionic conductivity as described in claim 1, characterized in that, The solid electrolyte is clay-like; The Young's modulus of the solid electrolyte is 0.5~2 GPa.

4. The flexible inorganic solid electrolyte with high ionic conductivity as described in claim 1, characterized in that, The room temperature ionic conductivity of the cold-pressed sheet obtained by the solid electrolyte under a stacking pressure of 30~100 MPa is 0.2~1 mS / cm.

5. The method for producing a flexible high-ionic-conductivity inorganic solid electrolyte according to any one of claims 1 to 4, characterized by, Includes the following steps: Under an inert atmosphere, lithium source, gallium source, oxygen source, chlorine source and optional doping source are mixed in a certain stoichiometric ratio to prepare the solid electrolyte, resulting in an electrolyte matrix mixed powder, which is then ball-milled to obtain the inorganic solid electrolyte.

6. The preparation method according to claim 5, characterized in that, The ball milling is a high-energy ball milling; the rotation speed of the ball milling is 200~1000 rpm; the mass ratio of the ball milling beads to the electrolyte matrix mixed powder is 20:1~100:1; the ball milling time is 3~60 h.

7. The preparation method according to claim 5, characterized in that, The lithium source is Li2O; the gallium source is selected from one or more of GaCl3, GaBr3, GaF3, Ga2O3, Ga(OH)3, Ga(NO3)3, Ga2(CO3)3, Ga2(SO4)3, GaOF, GaOCl, and GaOBr; the oxygen source and chlorine source are selected from one or more of the lithium source, gallium source, and doping source. The doping source is an anion doping source or a cation doping source; The anion doping source is selected from one or more of LiF, LiBr, LiI, Li2S, Li3N, Li2Se, Li2S, GaF3, GaBr3, GaI3, GaN, Ga2Se3, and Ga2S3; The cation doping source is selected from MF. α ,MCl α , MBr α MI α MN α MSe α MS α MO α One or more of them, where α is determined by the valence of M and the charge number of the corresponding anion, satisfying the charge balance rule; The molar ratio of lithium in the lithium source to gallium in the gallium source is 0.6 to 4.4; The molar ratio of lithium in the lithium source to oxygen in the oxygen source is 0.4~2; The molar ratio of gallium in the gallium source to chlorine in the chlorine source is 0.3~2; The molar ratio of gallium in the gallium source to cations in the cation-doped source is 1.5 to 9; The molar ratio of chlorine in the chlorine source to anion in the anion dopant source is 0.5 to 59.

8. Solid-state alkali metal battery, characterized by This includes the flexible inorganic solid electrolyte with high ionic conductivity as described in any one of claims 1 to 4, or the flexible inorganic solid electrolyte with high ionic conductivity prepared by the preparation method described in any one of claims 5 to 7.

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