Inorganic composite solid-state electrolyte, preparation method and application thereof

Abstract

This invention relates to the field of solid-state electrolyte technology, and discloses an inorganic composite solid-state electrolyte, its preparation method, and its application. The preparation method includes the following steps: mixing electrolyte raw material I and electrolyte raw material II and reacting them at 40-100°C; wherein electrolyte raw material I comprises Li₄(BH₄)₃I, and electrolyte raw material II comprises Li₃InCl₆ and Li a SbCl b In the preparation method of this invention, Li4(BH4)3I, Li3InCl6, and Li a SbCl b The reaction at the interface between them can endow the inorganic composite solid electrolyte with high ionic conductivity, while also improving its ability to suppress dendrite penetration, thus giving the battery better cycle stability.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte technology, and in particular to an inorganic composite solid electrolyte, its preparation method and application. Background Technology

[0002] Among numerous energy storage technologies, lithium-ion batteries have become the preferred choice for portable electronic devices, electric vehicles, and grid energy storage due to their high energy density, long cycle life, and low self-discharge rate. However, traditional lithium-ion batteries use liquid electrolytes, which have some inherent limitations. Liquid electrolytes are typically composed of organic solvents and lithium salts, and are flammable and volatile, posing safety hazards. Furthermore, the interfacial stability between liquid electrolytes and electrode materials is poor, easily leading to side reactions in the electrode materials and electrolyte decomposition, affecting the battery's cycle life and safety. To overcome these challenges, researchers have begun exploring novel electrolyte materials, among which solid-state electrolytes have attracted considerable attention due to their advantages such as high safety, high energy density, wide voltage operating range, and wide operating temperature range.

[0003] Significant progress has been made in the research of various solid-state electrolytes over the past few decades. In particular, halide and hydride electrolytes, which have begun to be developed in recent years, have rapidly gained attention in the scientific community due to their unique electrochemical advantages. However, both types of electrolytes face problems such as instability with lithium metal and low lithium-ion conductivity at room temperature, which limit the selection of their operating voltage range and temperature range. It is difficult for a single halide electrolyte or a single hydride electrolyte to simultaneously meet the chemical / electrochemical compatibility with mainstream positive and negative electrode materials. Therefore, the combined effect of two or more solid-state electrolytes in all-solid-state batteries is beginning to receive more attention and research.

[0004] By blending or layering halide electrolytes and hydride electrolytes, the complementary advantages of these two electrolytes can be achieved (e.g., patent CN118553992A). However, due to the chemical incompatibility and interfacial side reactions between the two electrolytes, Li+ at the interface is prone to occur. + The relatively weak conductivity affects the ionic conductivity of composite solid electrolytes. Currently, there is a lack of in-depth research and reports on the combination of halide and hydride electrolytes, and the interaction between the two and the resulting products, as well as their relative improvement or impact on the performance of the full cell, remain to be explored. Summary of the Invention

[0005] To address the Li... + To address the technical problem of poor conductivity, this invention provides a method for preparing an inorganic composite solid electrolyte. In this preparation method, Li4(BH4)3I and Li3InCl6 and / or Li a SbCl bThe reaction at the interface between them can endow the inorganic composite solid electrolyte with high ionic conductivity and give the battery high cycle stability.

[0006] The specific technical solution of this invention is as follows: In a first aspect, the present invention provides a method for preparing an inorganic composite solid electrolyte, comprising the steps of: mixing electrolyte raw material I and electrolyte raw material II and reacting them at 40-100°C; wherein electrolyte raw material I comprises Li4(BH4)3I, and electrolyte raw material II comprises Li3InCl6 and Li a SbCl b .

[0007] During the reaction at 40–100 °C, the reaction between Li₄(BH₄)₃I and Li₃InCl₆ is self-limiting, generating InI and LiCl at their interface. These two products are themselves good conductors of lithium ions and poor conductors of electrons. Furthermore, due to the presence of In... 3+ Become a low-price state In + Therefore, after the formation of the interface layer composed of InI and LiCl, the reaction rate is greatly reduced, which can prevent further reaction between Li4(BH4)3I and Li3InCl6, thus preserving the inherent properties of Li4(BH4)3I and Li3InCl6 to a greater extent. Furthermore, the interface layer formed in situ has good continuity with Li4(BH4)3I and Li3InCl6, ensuring good contact between the two without reducing the overall ionic conductivity. In addition, if the electrolyte is pierced by lithium dendrites, the interface layer can react with lithium to form a new LiI and lithium-indium alloy with good ionic conductivity, further transforming the lithium dendrites into the electrolyte layer, thereby preventing short circuits caused by lithium dendrite growth.

[0008] Similarly, Li a SbCl b Li4(BH4)3I also has the above-mentioned effects, and the SbI and LiCl generated at the interface of the two have similar effects to InI and LiCl.

[0009] Based on this, the present invention further employs Li3InCl6+Li4(BH4)3I+Li a SbCl b In addition to the aforementioned compounding schemes, the combinations of Li4(BH4)3I and Li3InCl6, and Li4(BH4)3I and Li a SbCl bA self-limiting reaction occurs between them to generate an interface layer composed of InI, SbI, and LiCl. In addition to good lithium-ion conductivity, this interface layer can also produce the following effects: InI can effectively suppress the interfacial side reactions of the electrodes by reacting with the positive and negative electrode materials or acting as a physical isolation layer, significantly improving cycle stability. The role of SbI is to build high conductivity. Sb doping can synergistically reconstruct the crystal structure of the material with I element, forming huge lithium-ion migration channels, achieving ultrafast ion conduction comparable to or even exceeding that of liquid electrolytes. The synergistic doping of In and Sb is an effective strategy to achieve a comprehensive performance of high ionic conductivity, good interfacial stability, and excellent air stability.

[0010] Preferably, the specific steps of the preparation method include: taking Li a SbCl b The product is mixed with the first part Li4(BH4)3I and reacted at 40~100℃ for 1~4h. Then the product is mixed with Li3InCl6 and the second part Li4(BH4)3I and reacted at 40~100℃ for 1~4h.

[0011] In the above preparation steps, Li is first... a SbCl b The mixture reacts with the first part Li4(BH4)3I, and then Li3InCl6 and the second part Li4(BH4)3I are added to continue the reaction. This allows SbI to be distributed in the inner layer, which is used to construct the overall electrolyte material with high lithium-ion conductivity. InI is distributed in the outer layer, which is beneficial as a stabilizer for the interfacial side reactions between the electrolyte and the electrode material, thereby improving cycle stability.

[0012] Preferably, the Li a SbCl b It is one or more of LiSbCl6, Li3SbCl6, and LiSbCl4; the molar ratio of electrolyte raw material I to electrolyte raw material II is 0.3~0.8:1; the Li3InCl6 and Li a SbCl b The molar ratio is 1~1.5:1.

[0013] Preferably, the Li a SbCl b The first part of Li4(BH4)3I is mixed by grinding for 10-30 min; the product is mixed with Li3InCl6 and the second part of Li4(BH4)3I by grinding for 10-30 min; the molar ratio between the first part of Li4(BH4)3I and the second part of Li4(BH4)3I is 0.5-2:1.

[0014] Secondly, the present invention provides an inorganic composite solid electrolyte prepared by the aforementioned preparation method.

[0015] Thirdly, the present invention provides the application of the inorganic composite solid electrolyte in all-solid-state lithium batteries.

[0016] Preferably, the all-solid-state lithium battery includes a solid electrolyte sheet and a positive electrode sheet and a negative electrode sheet respectively disposed on both sides of the solid electrolyte sheet; the solid electrolyte sheet contains the inorganic composite solid electrolyte.

[0017] Preferably, the positive electrode contains electrolyte material II; and the negative electrode contains electrolyte material I.

[0018] Preferably, the positive electrode sheet also contains a positive electrode active material and a conductive material; the contents of the positive electrode active material, the conductive material and the electrolyte raw material II in the positive electrode sheet are 20~70 wt%, 3~60 wt% and 20~30 wt%, respectively.

[0019] Preferably, the negative electrode sheet also contains a negative electrode active material and a conductive material; the contents of the negative electrode active material, the conductive material and the electrolyte raw material I in the negative electrode sheet are 50~90 wt%, 5~25 wt% and 5~25 wt%, respectively.

[0020] Compared with the prior art, the present invention has the following advantages: (1) In the process of preparing inorganic composite solid electrolyte, this invention uses specific electrolyte raw materials for reaction, utilizing Li4(BH4)3I with Li3InCl6 and Li a SbCl b The self-limiting nature of the reaction and the characteristics of the reaction products enable the prepared inorganic composite solid electrolyte to have high ionic conductivity, while also improving its ability to suppress dendrite penetration.

[0021] (2) In the process of preparing the inorganic composite solid electrolyte, this invention utilizes InI generated by the reaction between Li4(BH4)3I and Li3InCl6, in conjunction with Li4(BH4)3I and Li a SbCl b The SbI generated by the reaction can improve the lithium-ion conductivity of the electrolyte and give the battery better cycle stability.

[0022] (3) In the process of preparing the inorganic composite solid electrolyte, the present invention first uses Li a SbCl bThe reaction is carried out by mixing the first part Li4(BH4)3I with the second part Li4(BH4)3I, and then adding Li3InCl6 and the second part Li4(BH4)3I to continue the reaction, which helps to improve the cycle stability of the battery to a greater extent. Attached Figure Description

[0023] Figure 1 The lithium-ion conductivity of the solid electrolytes in Examples 1-4 and Comparative Examples 1-4 at different temperatures.

[0024] Figure 2 This is a scanning electron microscope (SEM) image of the solid electrolyte in Comparative Example 1.

[0025] Figure 3 The image shows the energy dispersive spectroscopy (EDS) spectra of Cl and In elements in the solid electrolyte of Comparative Example 1.

[0026] Figure 4 This is a scanning electron microscope (SEM) image of the solid electrolyte in Comparative Example 2.

[0027] Figure 5 The image shows the energy dispersive spectroscopy (EDS) spectra of Cl and Sb elements in the solid electrolyte of Comparative Example 2. Detailed Implementation

[0028] The present invention will be further described below with reference to embodiments.

[0029] First, the present invention relates to a method for preparing an inorganic composite solid electrolyte, comprising the steps of: mixing electrolyte raw material I and electrolyte raw material II and reacting them at 40-100°C; wherein electrolyte raw material I comprises Li4(BH4)3I, and electrolyte raw material II comprises Li3InCl6 and Li a SbCl b .

[0030] In some specific embodiments, the preparation method includes the following steps: [The text abruptly ends here, so the translation stops.] a SbCl b The product is mixed with the first part Li4(BH4)3I and reacted at 40-100℃ for 1-4 hours. Then, the product is mixed with Li3InCl6 and the second part Li4(BH4)3I and reacted at 40-100℃ for 1-4 hours. Optionally or preferably, the Li... a SbCl b The first part of Li4(BH4)3I is mixed by grinding for 10-30 min; the product is mixed with Li3InCl6 and the second part of Li4(BH4)3I by grinding for 10-30 min; the molar ratio between the first part of Li4(BH4)3I and the second part of Li4(BH4)3I is 0.5-2:1.

[0031] In some specific embodiments, the Li a SbCl b It is one or more of LiSbCl6, Li3SbCl6 and LiSbCl4.

[0032] In some specific embodiments, the molar ratio of electrolyte raw material I to electrolyte raw material II is 0.3~0.8:1.

[0033] In some specific embodiments, the Li3InCl6 and Li a SbCl b The molar ratio is 1~1.5:1.

[0034] Second, the present invention relates to an inorganic composite solid electrolyte prepared by the aforementioned preparation method.

[0035] Third, the present invention relates to the application of the inorganic composite solid electrolyte in all-solid-state lithium batteries.

[0036] In some specific embodiments, the all-solid-state lithium battery includes a solid electrolyte sheet and a positive electrode sheet and a negative electrode sheet respectively disposed on both sides of the solid electrolyte sheet; the solid electrolyte sheet contains the inorganic composite solid electrolyte.

[0037] In some specific embodiments, the positive electrode contains the electrolyte raw material II; the content of the electrolyte raw material II in the positive electrode is 20~30 wt%.

[0038] In some specific embodiments, the positive electrode sheet contains a positive electrode active material; the content of the positive electrode active material in the positive electrode sheet is 20~70 wt%.

[0039] In some specific embodiments, the positive electrode contains a conductive material; the content of the conductive material in the positive electrode is 3~60 wt%; the conductive material includes one or more of Ketjen Black, Super-P, vapor-grown carbon nanofibers and carbon nanotubes.

[0040] In some specific embodiments, the negative electrode sheet contains the electrolyte raw material I; the content of the electrolyte raw material I in the negative electrode sheet is 5~25 wt%.

[0041] In some specific embodiments, the negative electrode sheet contains a negative electrode active material; the content of the negative electrode active material in the negative electrode sheet is 50~90 wt%; the negative electrode active material includes one or more of Li, Li-In alloy, Li-Mg alloy and Li-Sn alloy.

[0042] In some specific embodiments, the negative electrode sheet contains a conductive material; the content of the conductive material in the negative electrode sheet is 5~25 wt%; the conductive material includes one or more of Ketjen Black, Super-P, vapor-grown carbon nanofibers and carbon nanotubes.

[0043] In some specific embodiments, the preparation steps of the positive electrode sheet include: mixing all positive electrode materials, ball milling them in an inert atmosphere at a ball-to-material ratio of 50~400:1 and a rotation speed of 200~800 rpm for 1~24 h, and then pressing them into sheets.

[0044] In some specific embodiments, the preparation steps of the negative electrode sheet include: mixing all negative electrode materials, ball milling them in an inert atmosphere at a ball-to-material ratio of 60~200:1 and a rotation speed of 200~1000 rpm for 1~24 h, and then pressing them into sheets.

[0045] In some specific embodiments, the solid electrolyte sheet is obtained by pressing the inorganic composite solid electrolyte into a sheet.

[0046] The present invention will now be described with reference to specific embodiments and comparative examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0047] Example 1

[0048] Inorganic composite solid electrolytes are prepared according to the following steps, and then further fabricated into lithium symmetric batteries and all-solid-state lithium batteries: S1: Preparation of Inorganic Composite Solid Electrolytes Li4(BH4)3I powder, Li3InCl6 powder, and LiSbCl6 powder were taken in a molar ratio of 1:1:1. The Li4(BH4)3I powder was divided into two parts for later use. The Li3InCl6 powder and the first part of Li4(BH4)3I powder were mixed and manually ground for 30 min. The resulting mixed powder was placed in a reaction tube and kept at 60℃ for 2 h. After naturally cooling to room temperature, the resulting product was mixed with LiSbCl6 powder and the second part of Li4(BH4)3I powder. After manually grinding for 30 min, the mixture was placed in a reaction tube and kept at 60℃ for 2 h. After naturally cooling to room temperature, the inorganic composite solid electrolyte was obtained.

[0049] S2: Fabrication of lithium-symmetric batteries An inorganic composite solid electrolyte is pressed into a sheet in a solid-state battery mold to obtain a solid electrolyte sheet. After attaching lithium metal sheets to both sides of the solid electrolyte sheet, a stainless steel frame is used to apply pressure to obtain a lithium symmetric battery.

[0050] S3: Fabrication of all-solid-state lithium batteries LiNi0.8 Co 0.1 Mn 0.1 O2, Li3InCl6, LiSbCl6, and carbon nanotubes were mixed in a mass ratio of 70:13.5:13.5:3, sealed in a ball mill jar, and grinding balls were added at a ball-to-material ratio of 200:1. The mixture was then bidirectionally ball-milled overnight at 600 rpm under an argon atmosphere to obtain the positive electrode composite material. Li, Li4(BH4)3I, and carbon nanotubes were mixed in a mass ratio of 70:27:3, sealed in a ball mill jar, and grinding balls were added at a ball-to-material ratio of 100:1. The mixture was then bidirectionally ball-milled overnight at 800 rpm under an argon atmosphere to obtain the negative electrode composite material. The inorganic composite solid electrolyte was pressed into a sheet in a solid-state battery mold to form a solid electrolyte sheet. The positive electrode composite material was poured onto one side of the solid electrolyte sheet and pressed into a sheet. The negative electrode composite material was poured onto the other side of the solid electrolyte sheet and pressed into a sheet to obtain an all-solid-state lithium battery.

[0051] Example 2

[0052] Inorganic composite solid electrolytes are prepared according to the following steps, and then further fabricated into lithium symmetric batteries and all-solid-state lithium batteries: S1: Preparation of Inorganic Composite Solid Electrolytes Li4(BH4)3I powder, Li3InCl6 powder, and Li3SbCl6 powder were prepared in a molar ratio of 3:6:4. The Li4(BH4)3I powder was divided into two parts for later use. The Li3InCl6 powder and the first part of Li4(BH4)3I powder were mixed and manually ground for 30 min. The resulting mixed powder was placed in a reaction tube and kept at 40℃ for 4 h. After naturally cooling to room temperature, the resulting product was mixed with the Li3SbCl6 powder and the second part of Li4(BH4)3I powder. The mixture was manually ground for 30 min and then placed in a reaction tube. The mixture was kept at 40℃ for 4 h and then naturally cooled to room temperature to obtain the inorganic composite solid electrolyte.

[0053] S2: Fabrication of lithium-symmetric batteries An inorganic composite solid electrolyte is pressed into a sheet in a solid-state battery mold to obtain a solid electrolyte sheet. After attaching lithium metal sheets to both sides of the solid electrolyte sheet, a stainless steel frame is used to apply pressure to obtain a lithium symmetric battery.

[0054] S3: Fabrication of all-solid-state lithium batteries LiNi 0.8 Co 0.1 Mn 0.1O2, Li3InCl6, Li3SbCl6, and carbon nanotubes were mixed in a mass ratio of 70:13.5:13.5:3, sealed in a ball mill jar, and grinding balls were added at a ball-to-material ratio of 200:1. The mixture was then bidirectionally ball-milled overnight at 600 rpm under an argon atmosphere to obtain the positive electrode composite material. Li, Li4(BH4)3I, and carbon nanotubes were mixed in a mass ratio of 70:27:3, sealed in a ball mill jar, and grinding balls were added at a ball-to-material ratio of 100:1. The mixture was then bidirectionally ball-milled overnight at 800 rpm under an argon atmosphere to obtain the negative electrode composite material. The inorganic composite solid electrolyte was pressed into a sheet in a solid-state battery mold to form a solid electrolyte sheet. The positive electrode composite material was then poured onto one side of the solid electrolyte sheet and pressed into a sheet. The negative electrode composite material was poured onto the other side of the solid electrolyte sheet and pressed into a sheet to obtain an all-solid-state lithium battery.

[0055] Example 3

[0056] Inorganic composite solid electrolytes are prepared according to the following steps, and then further fabricated into lithium symmetric batteries and all-solid-state lithium batteries: S1: Preparation of Inorganic Composite Solid Electrolytes Li4(BH4)3I powder, Li3InCl6 powder, and LiSbCl4 powder were prepared in a molar ratio of 8:5:5. The Li4(BH4)3I powder was divided into two parts for later use. The Li3InCl6 powder and the first part of Li4(BH4)3I powder were mixed and manually ground for 30 min. The resulting mixed powder was placed in a reaction tube and kept at 100℃ for 1 h. After cooling to room temperature, the resulting product was mixed with LiSbCl4 powder and the second part of Li4(BH4)3I powder and manually ground for 30 min. The mixture was then placed in a reaction tube and kept at 100℃ for 1 h. After cooling to room temperature, the inorganic composite solid electrolyte was obtained.

[0057] S2: Fabrication of lithium-symmetric batteries An inorganic composite solid electrolyte is pressed into a sheet in a solid-state battery mold to obtain a solid electrolyte sheet. After attaching lithium metal sheets to both sides of the solid electrolyte sheet, a stainless steel frame is used to apply pressure to obtain a lithium symmetric battery.

[0058] S3: Fabrication of all-solid-state lithium batteries LiNi 0.8 Co 0.1 Mn 0.1O2, Li3InCl6, LiSbCl4, and carbon nanotubes were mixed in a mass ratio of 70:13.5:13.5:3, sealed in a ball mill jar, and grinding balls were added at a ball-to-material ratio of 200:1. The mixture was then bidirectionally ball-milled overnight at 600 rpm under an argon atmosphere to obtain the positive electrode composite material. Li, Li4(BH4)3I, and carbon nanotubes were mixed in a mass ratio of 70:27:3, sealed in a ball mill jar, and grinding balls were added at a ball-to-material ratio of 100:1. The mixture was then bidirectionally ball-milled overnight at 800 rpm under an argon atmosphere to obtain the negative electrode composite material. The inorganic composite solid electrolyte was pressed into a sheet in a solid-state battery mold to form a solid electrolyte sheet. The positive electrode composite material was poured onto one side of the solid electrolyte sheet and pressed into a sheet. The negative electrode composite material was poured onto the other side of the solid electrolyte sheet and pressed into a sheet to obtain an all-solid-state lithium battery.

[0059] Example 4

[0060] The difference between this embodiment and Embodiment 1 is that a batch feeding method was not used in the preparation of the inorganic composite solid electrolyte. Specifically, this embodiment prepares the inorganic composite solid electrolyte according to the following steps, and further fabricates it into a lithium symmetric battery and an all-solid-state lithium battery: S1: Preparation of Inorganic Composite Solid Electrolytes Li4(BH4)3I powder, Li3InCl6 powder, and LiSbCl6 powder were prepared in a molar ratio of 1:1:1 and set aside. The Li4(BH4)3I powder, Li3InCl6 powder, and LiSbCl6 powder were mixed and manually ground for 30 min. The resulting mixed powder was placed in a reaction tube and kept at 60℃ for 4 h. After naturally cooling to room temperature, an inorganic composite solid electrolyte was obtained.

[0061] S2: Fabrication of lithium-symmetric batteries An inorganic composite solid electrolyte is pressed into a sheet in a solid-state battery mold to obtain a solid electrolyte sheet. After attaching lithium metal sheets to both sides of the solid electrolyte sheet, a stainless steel frame is used to apply pressure to obtain a lithium symmetric battery.

[0062] S3: Fabrication of all-solid-state lithium batteries LiNi 0.8 Co 0.1 Mn 0.1O2, Li3InCl6, LiSbCl6, and carbon nanotubes were mixed in a mass ratio of 70:13.5:13.5:3, sealed in a ball mill jar, and grinding balls were added at a ball-to-material ratio of 200:1. The mixture was then bidirectionally ball-milled overnight at 600 rpm under an argon atmosphere to obtain the positive electrode composite material. Li, Li4(BH4)3I, and carbon nanotubes were mixed in a mass ratio of 70:27:3, sealed in a ball mill jar, and grinding balls were added at a ball-to-material ratio of 100:1. The mixture was then bidirectionally ball-milled overnight at 800 rpm under an argon atmosphere to obtain the negative electrode composite material. The inorganic composite solid electrolyte was pressed into a sheet in a solid-state battery mold to form a solid electrolyte sheet. The positive electrode composite material was poured onto one side of the solid electrolyte sheet and pressed into a sheet. The negative electrode composite material was poured onto the other side of the solid electrolyte sheet and pressed into a sheet to obtain an all-solid-state lithium battery.

[0063] Comparative Example 1 The difference between this comparative example and Example 4 is that, in the preparation of the inorganic composite solid electrolyte, LiSbCl6 powder is replaced with an equimolar amount of Li3InCl6 powder. Specifically, this comparative example prepares the inorganic composite solid electrolyte according to the following steps, and further fabricates it into a lithium symmetric battery and an all-solid-state lithium battery: S1: Preparation of Inorganic Composite Solid Electrolytes Li4(BH4)3I powder and Li3InCl6 powder were prepared at a molar ratio of 1:2 and set aside. The Li4(BH4)3I powder and Li3InCl6 powder were mixed and manually ground for 30 min. The resulting mixture was placed in a reaction tube and kept at 60℃ for 4 h, then allowed to cool naturally to room temperature to obtain an inorganic composite solid electrolyte. Its surface morphology is shown in the figure. Figure 2 As shown, the distribution of Cl and In elements is as follows: Figure 3 As shown.

[0064] S2: Fabrication of lithium-symmetric batteries An inorganic composite solid electrolyte is pressed into a sheet in a solid-state battery mold to obtain a solid electrolyte sheet. After attaching lithium metal sheets to both sides of the solid electrolyte sheet, a stainless steel frame is used to apply pressure to obtain a lithium symmetric battery.

[0065] S3: Fabrication of all-solid-state lithium batteries LiNi 0.8 Co 0.1 Mn 0.1O2, Li3InCl6, and carbon nanotubes were mixed in a mass ratio of 70:27:3 and sealed in a ball mill jar. Milling beads were added, with a ball-to-material ratio of 200:1. The mixture was bidirectionally ball-milled overnight at 600 rpm under an argon atmosphere to obtain the positive electrode composite material. Li, Li4(BH4)3I, and carbon nanotubes were mixed in a mass ratio of 70:27:3 and sealed in a ball mill jar. Milling beads were added, with a ball-to-material ratio of 100:1. The mixture was bidirectionally ball-milled overnight at 800 rpm under an argon atmosphere to obtain the negative electrode composite material. The inorganic composite solid electrolyte was pressed into a sheet in a solid-state battery mold to form a solid electrolyte sheet. The positive electrode composite material was poured onto one side of the solid electrolyte sheet and pressed into a sheet. The negative electrode composite material was poured onto the other side of the solid electrolyte sheet and pressed into a sheet to obtain an all-solid-state lithium battery.

[0066] Comparative Example 2 The difference between this comparative example and Example 4 is that, in the preparation of the inorganic composite solid electrolyte, Li3InCl6 powder is replaced with an equimolar amount of LiSbCl6 powder. Specifically, this comparative example prepares the inorganic composite solid electrolyte according to the following steps, and further fabricates it into a lithium symmetric battery and an all-solid-state lithium battery: S1: Preparation of Inorganic Composite Solid Electrolytes Li₄(BH₄)₃I powder and LiSbCl₆ powder were prepared at a molar ratio of 1:2 and set aside. The Li₄(BH₄)₃I powder and LiSbCl₆ powder were mixed and manually ground for 30 min. The resulting mixture was placed in a reaction tube and kept at 60℃ for 4 h, then allowed to cool naturally to room temperature to obtain an inorganic composite solid electrolyte. Its surface morphology is shown in the figure. Figure 4 As shown, the distribution of Cl and Sb elements is as follows: Figure 5 As shown.

[0067] S2: Fabrication of lithium-symmetric batteries An inorganic composite solid electrolyte is pressed into a sheet in a solid-state battery mold to obtain a solid electrolyte sheet. After attaching lithium metal sheets to both sides of the solid electrolyte sheet, a stainless steel frame is used to apply pressure to obtain a lithium symmetric battery.

[0068] S3: Fabrication of all-solid-state lithium batteries LiNi 0.8 Co 0.1 Mn 0.1O2, LiSbCl6, and carbon nanotubes were mixed in a mass ratio of 70:27:3 and sealed in a ball mill jar. Milling beads were added, with a ball-to-material ratio of 200:1. The mixture was bidirectionally ball-milled overnight at 600 rpm under an argon atmosphere to obtain the positive electrode composite material. Li, Li4(BH4)3I, and carbon nanotubes were mixed in a mass ratio of 70:27:3 and sealed in a ball mill jar. Milling beads were added, with a ball-to-material ratio of 100:1. The mixture was bidirectionally ball-milled overnight at 800 rpm under an argon atmosphere to obtain the negative electrode composite material. The inorganic composite solid electrolyte was pressed into a sheet in a solid-state battery mold to form a solid electrolyte sheet. The positive electrode composite material was poured onto one side of the solid electrolyte sheet and pressed into a sheet. The negative electrode composite material was poured onto the other side of the solid electrolyte sheet and pressed into a sheet to obtain an all-solid-state lithium battery.

[0069] Comparative Example 3 The difference between this comparative example and Example 4 is that, in the preparation of the inorganic composite solid electrolyte, LiSbCl6 powder is replaced with an equimolar amount of LiNiCl3 powder. Specifically, this comparative example prepares the inorganic composite solid electrolyte according to the following steps, and further fabricates it into a lithium symmetric battery and an all-solid-state lithium battery: S1: Preparation of Inorganic Composite Solid Electrolytes Li4(BH4)3I powder, Li3InCl6 powder, and LiNiCl3 powder were prepared in a molar ratio of 1:1:1 and set aside. The Li4(BH4)3I powder, Li3InCl6 powder, and LiNiCl3 powder were mixed and manually ground for 30 min. The resulting mixed powder was placed in a reaction tube and kept at 60℃ for 4 h. After naturally cooling to room temperature, an inorganic composite solid electrolyte was obtained.

[0070] S2: Fabrication of lithium-symmetric batteries An inorganic composite solid electrolyte is pressed into a sheet in a solid-state battery mold to obtain a solid electrolyte sheet. After attaching lithium metal sheets to both sides of the solid electrolyte sheet, a stainless steel frame is used to apply pressure to obtain a lithium symmetric battery.

[0071] S3: Fabrication of all-solid-state lithium batteries LiNi 0.8 Co 0.1 Mn 0.1O2, Li3InCl6, LiNiCl3, and carbon nanotubes were mixed in a mass ratio of 70:13.5:13.5:3, sealed in a ball mill jar, and grinding balls were added at a ball-to-material ratio of 200:1. The mixture was then bidirectionally ball-milled overnight at 600 rpm under an argon atmosphere to obtain the positive electrode composite material. Li, Li4(BH4)3I, and carbon nanotubes were mixed in a mass ratio of 70:27:3, sealed in a ball mill jar, and grinding balls were added at a ball-to-material ratio of 100:1. The mixture was then bidirectionally ball-milled overnight at 800 rpm under an argon atmosphere to obtain the negative electrode composite material. The inorganic composite solid electrolyte was pressed into a sheet in a solid-state battery mold to form a solid electrolyte sheet. The positive electrode composite material was then poured onto one side of the solid electrolyte sheet and pressed into a sheet. The negative electrode composite material was poured onto the other side of the solid electrolyte sheet and pressed into a sheet to obtain an all-solid-state lithium battery.

[0072] Comparative Example 4 The difference between this comparative example and Example 4 is that in the preparation of the inorganic composite solid electrolyte, the electrolyte raw materials are simply mixed without reaction. Specifically, this comparative example prepares the inorganic mixed solid electrolyte according to the following steps, and further fabricates it into a lithium symmetric battery and an all-solid-state lithium battery: S1: Preparation of inorganic mixed solid electrolyte Li4(BH4)3I powder, Li3InCl6 powder, and LiSbCl6 powder were prepared in a molar ratio of 1:1:1 and set aside. The Li4(BH4)3I powder, Li3InCl6 powder, and LiSbCl6 powder were mixed and manually ground for 30 min to obtain an inorganic mixed solid electrolyte.

[0073] S2: Fabrication of lithium-symmetric batteries An inorganic mixed solid electrolyte is pressed into a sheet in a solid-state battery mold to obtain a solid electrolyte sheet. After attaching lithium metal sheets to both sides of the solid electrolyte sheet, a stainless steel frame is used to apply pressure to obtain a lithium symmetric battery.

[0074] S3: Fabrication of all-solid-state lithium batteries LiNi 0.8 Co 0.1 Mn 0.1O2, Li3InCl6, LiSbCl6, and carbon nanotubes were mixed in a mass ratio of 70:13.5:13.5:3, sealed in a ball mill jar, and grinding balls were added at a ball-to-material ratio of 200:1. The mixture was then bidirectionally ball-milled overnight at 600 rpm under an argon atmosphere to obtain the positive electrode composite material. Li, Li4(BH4)3I, and carbon nanotubes were mixed in a mass ratio of 70:27:3, sealed in a ball mill jar, and grinding balls were added at a ball-to-material ratio of 100:1. The mixture was then bidirectionally ball-milled overnight at 800 rpm under an argon atmosphere to obtain the negative electrode composite material. The inorganic mixed solid electrolyte was pressed into a sheet in a solid-state battery mold to form a solid electrolyte sheet. The positive electrode composite material was poured onto one side of the solid electrolyte sheet and pressed into a sheet. The negative electrode composite material was poured onto the other side of the solid electrolyte sheet and pressed into a sheet to obtain an all-solid-state lithium battery.

[0075] Test Example 1: Lithium-ion conductivity test of solid electrolyte The solid electrolytes prepared in Examples 1-4 and Comparative Examples 1-4 were used to test their lithium-ion conductivity at different temperatures. The results are shown in […]. Figure 1 ( Figure 1 In the x-axis, "T" represents Kelvin temperature.

[0076] Test Example 2: Cycle Stability Test of All-Solid-State Lithium Batteries The all-solid-state lithium batteries prepared in Examples 1-4 and Comparative Examples 1-4 were subjected to cycle stability tests. The remaining capacity rate after 100 charge-discharge cycles at 30°C and a charge-discharge rate of 1C was measured. The results are shown in Table 1.

[0077] Table 1. Cycle stability test results of all-solid-state lithium batteries

[0078] The experimental results from Test Case 1 and Test Case 2 show that: (1) Compared to Comparative Example 4, the solid electrolyte prepared in Example 4 has a higher lithium-ion conductivity. The reason for this is that Example 4 uses Li4(BH4)3I, Li3InCl6, and Li a SbCl b After mixing, a heating reaction was carried out, which generated InI, SbI, and LiCl at the interface of several electrolyte raw materials. These products can improve the lithium-ion conductivity at the interface; while Comparative Example 4 only used Li4(BH4)3I, Li3InCl6, and Li a SbCl b Simple blending cannot form the interfaces that are conducive to lithium-ion conduction, thus resulting in weak lithium-ion conduction capacity of solid electrolytes.

[0079] (2) The lithium-ion conductivity of the solid electrolyte prepared in Example 4 is higher than that of Comparative Example 1, and the cycle stability of the all-solid-state lithium battery prepared in Example 4 is better than that of Comparative Example 2. The reason for this is that Example 4 uses Li3InCl6+Li4(BH4)3I+Li a SbCl b In the compound formulation, the InI generated at the interface between Li4(BH4)3I and Li3InCl6 can effectively suppress interfacial side reactions of the electrodes by reacting with the positive and negative electrode materials or acting as a physical isolation layer, thereby improving cycle stability. Furthermore, the reaction between Li4(BH4)3I and Li... a SbCl b The SbI generated at the interface can provide good lithium-ion conductivity. By utilizing Sb doping and I element to synergistically reconstruct the crystal structure of the material, a huge lithium-ion migration channel is formed.

[0080] (3) Compared to Comparative Example 3, the solid electrolyte prepared in Example 4 has a higher lithium-ion conductivity. The reason for this is that Li₂ was used in Example 4. a SbCl b At the interface between Li4(BH4)3I and I, Sb doping can synergistically reconstruct the crystal structure of the material with I element, forming a huge lithium-ion migration channel; while in Comparative Example 3, the Li in Example 4... a SbCl b The above effect cannot be achieved when LiNiCl3 is used instead.

[0081] (4) Compared with Example 4, the all-solid-state lithium battery prepared in Example 1 has higher cycle stability. The reason for this is that Example 1 adopted a specific batch feeding and reaction method in the process of preparing the solid electrolyte (first feeding Li...). a SbCl b The mixture reacts with the first part Li4(BH4)3I, and then Li3InCl6 and the second part Li4(BH4)3I are added to continue the reaction. This allows SbI to be distributed in the inner layer, which is used to construct the overall electrolyte material with high lithium-ion conductivity. InI is distributed in the outer layer, which is beneficial as a stabilizer for the interfacial side reactions between the electrolyte and the electrode material, thereby improving cycle stability.

Claims

1. A method for preparing an inorganic composite solid electrolyte, characterized in that the steps include... include: Electrolyte raw material I and electrolyte raw material II are mixed and reacted at 40-100°C; electrolyte raw material I includes Li4(BH4)3I, and electrolyte raw material II includes Li3InCl6 and Li a SbCl b .

2. The preparation method according to claim 1, characterized in that, The specific steps include: [Li] a SbCl b The product is mixed with the first part Li4(BH4)3I and reacted at 40~100℃ for 1~4h. Then the product is mixed with Li3InCl6 and the second part Li4(BH4)3I and reacted at 40~100℃ for 1~4h.

3. The preparation method according to claim 1 or 2, characterized in that, The Li a SbCl b It is one or more of LiSbCl6, Li3SbCl6, and LiSbCl4; the molar ratio of electrolyte raw material I to electrolyte raw material II is 0.3~0.8:1; the Li3InCl6 and Li a SbCl b The molar ratio is 1~1.5:

1.

4. The preparation method according to claim 2, characterized in that, The Li a SbCl b The first part of Li4(BH4)3I is mixed by grinding for 10-30 min; the product is mixed with Li3InCl6 and the second part of Li4(BH4)3I by grinding for 10-30 min; the molar ratio between the first part of Li4(BH4)3I and the second part of Li4(BH4)3I is 0.5-2:

1.

5. An inorganic composite solid electrolyte prepared by the preparation method according to any one of claims 1 to 4.

6. The application of the inorganic composite solid electrolyte according to claim 5 in all-solid-state lithium batteries.

7. The application according to claim 6, characterized in that, The all-solid-state lithium battery includes a solid electrolyte sheet and a positive electrode sheet and a negative electrode sheet respectively disposed on both sides of the solid electrolyte sheet; the solid electrolyte sheet contains the inorganic composite solid electrolyte.

8. The application according to claim 7, characterized in that, The positive electrode contains electrolyte material II; the negative electrode contains electrolyte material I.

9. The application according to claim 8, characterized in that, The positive electrode sheet also contains positive electrode active material and conductive material; the contents of positive electrode active material, conductive material and electrolyte raw material II in the positive electrode sheet are 20~70 wt%, 3~60 wt% and 20~30 wt%, respectively.

10. The application according to claim 8, characterized in that, The negative electrode sheet also contains a negative electrode active material and a conductive material; the contents of the negative electrode active material, the conductive material and the electrolyte raw material I in the negative electrode sheet are 50~90 wt%, 5~25 wt% and 5~25 wt%, respectively.

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