Methods for in-situ preparation of halide electrolyte membrane materials and composite electrolyte membranes

Abstract

This invention discloses a method for in-situ preparation of halide electrolyte membrane materials and a composite electrolyte membrane, belonging to the field of solid-state battery materials technology. The method includes: immersing a three-dimensional lithium-ion conductive framework in an aqueous solution containing a lithium halide precursor, causing the halide electrolyte precursor to deposit in-situ within the framework pores to obtain a precursor-framework composite; subsequently drying to obtain the composite electrolyte membrane. Cucurbita urea is further introduced, whose rigid macrocyclic cavities selectively contain Li. + Furthermore, the ion transport pathway was modulated to synergistically construct ion channels with high mobility numbers and low interfacial impedance. The resulting electrolyte exhibited a room-temperature ionic conductivity of 1.8–2.2 mS·cm. －1 Electrochemical window > 4.8V, lithium-ion transference number t r It exhibits a pH value ≥0.80 and excellent air stability. This invention breaks through the limitations of traditional dry sintering processes, achieving low-cost, scalable, and structurally integrated halide solid electrolyte preparation.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery materials technology, specifically to a method for in-situ preparation of halide electrolyte membrane materials, and a composite electrolyte membrane prepared by the method. Background Technology

[0002] All-solid-state lithium batteries are considered a crucial development direction for next-generation electrochemical energy storage devices due to their high safety and high energy density potential. As the core component of all-solid-state batteries, the performance of the solid electrolyte directly determines the overall performance of the battery. Among various solid electrolyte candidates, halide solid electrolytes have attracted significant attention due to their wide electrochemical window, high ionic conductivity, and good compatibility with high-voltage cathode materials.

[0003] However, traditional methods for preparing halide solid electrolytes mainly rely on dry processes such as high-temperature solid-state sintering or high-energy ball milling, which have the following prominent drawbacks: (1) Dry sintering has high energy consumption and does not have the advantage of batch preparation. It consumes a lot of energy and halides are easily lost due to volatilization at high temperatures, making component control difficult; (2) The resulting electrolyte is usually in powder form and needs to be pressed into sheets, making it difficult to prepare a thin-film electrolyte layer. In addition, there are a large number of grain boundaries between the powder particles, which hinder ion transport; (3) The electrolyte layer prepared by the dry process has poor interfacial contact with the electrode material, resulting in high interfacial impedance, which seriously affects battery performance; (4) Powder electrolytes are extremely sensitive to air humidity, and the preparation and storage conditions are harsh, limiting large-scale production.

[0004] Therefore, there is an urgent need to develop a new method for preparing halide solid electrolytes with mild process conditions, integrated product structure, excellent interfacial compatibility, and good air stability. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for in-situ preparation of halide electrolyte membrane materials. This method is simple, mild, and low in cost, and the resulting electrolyte membrane has excellent ionic conductivity, wide electrochemical window, high lithium-ion transport number, and good air stability.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for in-situ preparation of halide electrolyte membrane materials includes the following steps: (1) The three-dimensional lithium-ion conductive framework composed of LLZO nanowires is immersed in an aqueous solution containing lithium halide precursor and left to stand at 20~80℃ to allow the halide electrolyte precursor to be deposited in situ in the channels of the three-dimensional lithium-ion conductive framework to obtain a precursor-framework composite. (2) The precursor-skeleton composite is vacuum dried at 200°C to obtain an integrated composite electrolyte membrane.

[0007] This invention employs an aqueous in-situ deposition process, using a three-dimensional network of LLZO nanowires as a lithium-ion transport framework. The halide electrolyte precursor is impregnated into the nanopores of the framework via solution immersion, achieving in-situ deposition of the precursor under mild temperature conditions (20–80°C). The LLZO nanowire framework not only provides continuous lithium-ion transport channels, but its three-dimensional network structure also provides mechanical support and a structural template for the halide electrolyte, resulting in an electrolyte film with both high ionic conductivity and good mechanical integrity. Subsequent vacuum drying at 200°C simultaneously achieves complete solvent removal and optimizes electrolyte crystallinity. The entire process is simple and controllable, requiring no energy-intensive high-temperature sintering equipment, and is easily scalable for large-scale production.

[0008] Furthermore, the lithium-containing halide precursor includes LiCl and InCl3. LiCl and InCl3, as a typical precursor combination for halide solid electrolytes, possess good water solubility and a suitable crystallization temperature, and can form a Li3InCl6 type halide electrolyte phase with high ionic conductivity under vacuum drying conditions at 200℃. Their uniform mixing in aqueous solution lays the foundation for component homogeneity in subsequent in-situ deposition.

[0009] Further, the settling time in step (1) is 1.5 to 2.5 hours. This time range ensures that the precursor solution fully penetrates into the pores of the framework and completes the deposition and nucleation process. If the time is too short, the deposition will be insufficient, and if the time is too long, it may lead to overgrowth or side reactions. Preferably, the vacuum drying time in step (2) is 3 to 5 hours. This drying time ensures that moisture and other volatile components are completely removed, while avoiding excessive drying time from adversely affecting the electrolyte microstructure.

[0010] As a further improvement of the present invention, 0.1~1.5 wt% of cucurbitaurea is also introduced into the aqueous solution, wherein the rigid macrocyclic cavity of the cucurbitaurea selectively contains Li. ＋ It also regulates ion transport pathways. Cucurbitaureus, as a supramolecular host compound with a rigid macrocyclic cavity structure, has a cavity size that matches well with the ionic radius of Li⁺, enabling it to selectively transport Li⁺. ＋ Contained within the cavity, cucurbituril creates a steric hindrance effect on larger anions. When the content is below 0.1 wt%, the amount of cucurbituril is insufficient to form a continuous ion-regulating network in the electrolyte membrane; when the content is above 1.5 wt%, excessive cucurbituril molecules may aggregate, hindering ion transport. Within the preferred addition range of 0.1~1.5 wt%, cucurbituril molecules are uniformly dispersed in the halide electrolyte matrix, and its rigid cavity provides a directional transport channel for Li⁺, effectively suppressing anion migration and the formation of a space charge layer, thereby significantly improving the lithium-ion transference number (t). r≥0.80), and reduce the interfacial impedance between the electrolyte and the electrode.

[0011] This invention also provides an integrated composite electrolyte membrane prepared by the above method. This electrolyte membrane exhibits the following excellent electrochemical properties: a room temperature ionic conductivity of 1.8–2.2 mS·cm. －1 Electrochemical window greater than 4.8V, lithium-ion transference number t r ≥0.80.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The aqueous phase in-situ deposition process is adopted, which breaks through the temperature limit of traditional dry sintering. The electrolyte membrane can be prepared under mild conditions of 200℃, which greatly reduces energy consumption. The process is simple and controllable and easy to scale up production.

[0013] (2) Using a three-dimensional lithium-ion conductive framework composed of LLZO nanowires as a template, in-situ uniform filling of halide electrolyte is achieved to form a structurally integrated composite electrolyte membrane. The framework provides continuous ion transport channels and mechanical support, effectively reducing interfacial impedance and improving the cycle stability of the battery.

[0014] (3) By introducing cucurbita supramolecular additives, the rigid macrocyclic cavity of cucurbita is utilized to enhance the effect of Li + The selective inclusion effect allows for the construction of ion transport channels with high mobility numbers and low interfacial impedance. Lithium-ion mobility number t r ≥0.80, significantly better than traditional halide electrolytes.

[0015] (4) The resulting composite electrolyte membrane has both high ionic conductivity (1.8~2.2 mS·cm) and high ionic conductivity. －1 It features a wide electrochemical window (>4.8V) and excellent air stability (its ionic conductivity can be restored by re-annealing after 12 hours of exposure to low humidity air), with a capacity retention of >85% after 1000 cycles. Its overall performance is excellent and it is suitable for high energy density all-solid-state lithium batteries. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a flowchart of a method for in-situ preparation of halide electrolyte membrane materials provided in Embodiment 1 of this application. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below with reference to specific embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0018] Example 1 like Figure 1 As shown, Example 1 provides a method for in-situ preparation of halide electrolyte membrane materials, comprising the following steps: Step 1: Preparation of precursor solution; Weigh out stoichiometric amounts of LiCl and InCl3, dissolve them in deionized water, and stir at room temperature for 30 minutes to prepare an aqueous solution of lithium halide precursor with a concentration of 0.5 mol / L.

[0019] Step 2: Skeleton impregnation and in-situ deposition; The pre-prepared three-dimensional lithium-ion conductive framework composed of LLZO nanowires was immersed in the precursor aqueous solution obtained in step one and allowed to stand at 20°C for 2.5 hours. During this process, the lithium halide-containing precursor solution fully penetrated into the three-dimensional porous network of the LLZO nanowire framework and deposited nuclei in situ on the nanowire surface, obtaining a precursor-framework composite. This low-temperature standing process ensured uniform deposition of the precursor, avoided component segregation caused by rapid precipitation, and facilitated the subsequent formation of a uniform and dense electrolyte layer.

[0020] Step 3: Vacuum drying.

[0021] The precursor-skeleton composite obtained in step two was removed and placed in a vacuum drying oven, where it was vacuum dried at 200°C for 4 hours. The vacuum environment promoted the efficient removal of solvent molecules, and the drying temperature of 200°C effectively drove the solid-phase reaction between LiCl and InCl3, forming a highly crystalline Li3InCl6 type halide electrolyte phase. Simultaneously, a tight interfacial bond was formed between the LLZO nanowire skeleton and the halide electrolyte, ultimately resulting in a structurally integrated composite electrolyte membrane. The room temperature ionic conductivity of the electrolyte membrane obtained in this example is 1.8 mS·cm. －1 The electrochemical window is 4.9V, and the lithium-ion transference number t r It is 0.78.

[0022] Example 2 Example 2 provides a method for in-situ preparation of halide electrolyte membrane materials, comprising the following steps: Step 1: Preparation of precursor solution; Weigh out stoichiometric amounts of LiCl and InCl3, dissolve them in deionized water, and stir at room temperature for 30 minutes to prepare an aqueous solution of lithium halide precursor with a concentration of 0.5 mol / L.

[0023] Step 2: Skeleton impregnation and in-situ deposition; The pre-prepared three-dimensional lithium-ion-conducting framework composed of LLZO nanowires was immersed in the precursor aqueous solution obtained in step one and allowed to stand at 50°C for 2 hours. At this temperature, the viscosity of the precursor solution decreased, which was more conducive to its penetration into the nanoscale channels of the framework. At the same time, the moderate temperature promoted the uniform nucleation and deposition of the precursor, resulting in a precursor-framework composite.

[0024] Step 3: Vacuum drying.

[0025] The precursor-skeleton composite obtained in step two was removed and placed in a vacuum drying oven at 200°C for 4 hours to obtain an integrated composite electrolyte membrane. The room temperature ionic conductivity of the obtained electrolyte membrane was 2.0 mS·cm. －1 The electrochemical window is 4.9V, and the lithium-ion transference number t r It is 0.79.

[0026] Example 3 Example 1 provides a method for in-situ preparation of halide electrolyte membrane materials, comprising the following steps: Step 1: Preparation of precursor solution; Weigh out stoichiometric amounts of LiCl and InCl3, dissolve them in deionized water, and stir at room temperature for 30 minutes to prepare an aqueous solution of lithium halide precursor with a concentration of 0.5 mol / L.

[0027] Step 2: Skeleton impregnation and in-situ deposition; The pre-prepared three-dimensional lithium-ion conductive framework composed of LLZO nanowires was immersed in the precursor aqueous solution obtained in step one and allowed to stand at 80°C for 1.5 hours. The higher temperature accelerated the thermal motion of the precursor molecules, enabling them to fully penetrate into the framework channels and deposit in situ within a shorter time, thus obtaining the precursor-framework composite.

[0028] Step 3: Vacuum drying.

[0029] The precursor-skeleton composite obtained in step two was removed and placed in a vacuum drying oven at 200°C for 3 hours to obtain an integrated composite electrolyte membrane. The room temperature ionic conductivity of the obtained electrolyte membrane was 2.2 mS·cm. －1 The electrochemical window is 4.8V, and the lithium-ion transference number t r It is 0.80.

[0030] Example 4 Example 4 provides a method for in-situ preparation of halide electrolyte membrane materials, comprising the following steps: Step 1: Preparation of the precursor solution containing cucurbituril; Stoichiometric amounts of LiCl and InCl3 were weighed and dissolved in deionized water. The solution was stirred at room temperature for 30 minutes to prepare a 0.5 mol / L aqueous solution containing a lithium halide precursor. Subsequently, 0.1 wt% cucurbituril was added to the solution and ultrasonically dispersed for 30 minutes to ensure uniform dispersion of cucurbituril molecules in the precursor solution. Cucurbituril, as a supramolecular host compound with a rigid macrocyclic cavity structure, has a cavity size that matches well with the ionic radius of Li⁺, enabling it to selectively encapsulate Li⁺ within the cavity.

[0031] Step 2: Skeleton impregnation and in-situ deposition; The pre-prepared three-dimensional lithium-ion conductive framework composed of LLZO nanowires was immersed in the aqueous solution of the precursor containing cucurbita obtained in step one, and left to stand at 50°C for 2 hours. During this process, cucurbita molecules permeate into the framework channels along with the precursor solution and are uniformly distributed in the deposited halide electrolyte precursor, thus obtaining a cucurbita-containing precursor-framework complex.

[0032] Step 3: Vacuum drying.

[0033] The precursor-skeletal composite obtained in step two was removed and placed in a vacuum drying oven, where it was vacuum dried at 200°C for 4 hours to obtain an integrated composite electrolyte membrane containing cucurbituril. The rigid macrocyclic cavities of cucurbituril form an interaction between Li and the electrolyte membrane. + The selectively encapsulating ion transport channels effectively suppressed anion migration and the formation of a space charge layer, significantly increasing the lithium-ion transference number and reducing interfacial impedance. The resulting electrolyte membrane exhibited a room-temperature ionic conductivity of 2.1 mS·cm. －1 The electrochemical window is 5.0 V, and the lithium-ion transference number t r The conductivity is 0.85. After being exposed to 3% humidity for 24 hours, the conductivity retention rate is 89%. After being assembled into an all-solid-state lithium battery, the capacity retention rate is 87% after 1000 cycles.

[0034] Example 5 Example 5 provides a method for in-situ preparation of halide electrolyte membrane materials, comprising the following steps: Step 1: Preparation of the precursor solution containing cucurbituril; Weigh out stoichiometric amounts of LiCl and InCl3, dissolve them in deionized water, and stir at room temperature for 30 minutes to prepare an aqueous solution of lithium halide precursor with a concentration of 0.5 mol / L. Then, add 0.8 wt% cucurbituril to the solution and sonicate for 30 minutes to ensure uniform dispersion of cucurbituril molecules in the precursor solution.

[0035] Step 2: Skeleton impregnation and in-situ deposition; The pre-prepared three-dimensional lithium-ion-conducting framework composed of LLZO nanowires was immersed in the aqueous solution of the precursor containing cucurbita obtained in step one, and left to stand at 50°C for 2 hours to obtain the precursor-framework composite containing cucurbita.

[0036] Step 3: Vacuum drying.

[0037] The precursor-skeletal composite obtained in step two was removed and placed in a vacuum drying oven at 200°C for 4 hours to obtain an integrated composite electrolyte membrane containing cucurbituril. The room temperature ionic conductivity of the obtained electrolyte membrane was 2.0 mS·cm. －1 The electrochemical window is 5.0 V, and the lithium-ion transference number t r The conductivity is 0.88. After being exposed to 3% humidity for 24 hours, the conductivity retention rate is 91%. After being assembled into an all-solid-state lithium battery, the capacity retention rate is 89% after 1000 cycles.

[0038] Example 6 Example 6 provides a method for in-situ preparation of halide electrolyte membrane materials, comprising the following steps: Step 1: Preparation of the precursor solution containing cucurbituril; Weigh out stoichiometric amounts of LiCl and InCl3, dissolve them in deionized water, and stir at room temperature for 30 minutes to prepare an aqueous solution of lithium halide precursor with a concentration of 0.5 mol / L. Then, add 1.5 wt% cucurbituril to the solution and sonicate for 30 minutes to ensure uniform dispersion of cucurbituril molecules in the precursor solution.

[0039] Step 2: Skeleton impregnation and in-situ deposition; The pre-prepared three-dimensional lithium-ion-conducting framework composed of LLZO nanowires was immersed in the aqueous solution of the precursor containing cucurbita obtained in step one, and left to stand at 50°C for 2 hours to obtain the precursor-framework composite containing cucurbita.

[0040] Step 3: Vacuum drying.

[0041] The precursor-skeleton composite obtained in step two was removed and placed in a vacuum drying oven at 200°C for 4 hours to obtain an integrated composite electrolyte membrane containing cucurbitacin. When the cucurbitacin content reached 1.5 wt%, its rigid macrocyclic cavities formed a dense selective ion transport network in the electrolyte membrane, achieving the highest lithium-ion transport number. The resulting electrolyte membrane exhibited a room-temperature ionic conductivity of 1.9 mS·cm. －1 The electrochemical window is 4.9V, and the lithium-ion transference number t r The conductivity is 0.92. After being exposed to 3% humidity for 24 hours, the conductivity retention rate is 88%. After being assembled into an all-solid-state lithium battery, the capacity retention rate is 86% after 1000 cycles.

[0042] Comparative Example 1 (Traditional Dry Sintering) Stoichiometric amounts of LiCl and InCl3 powders were uniformly mixed by high-energy ball milling, followed by solid-state sintering at 400°C for 12 hours to obtain halide electrolyte powder. The resulting powder was then cold-pressed to prepare electrolyte sheets. The room-temperature ionic conductivity of the electrolyte obtained in this comparative example was 1.2 mS·cm. －1 Lithium-ion transference number t r The value was 0.65, and after 24 hours of exposure to 3% humidity, the conductivity retention rate was only 45%.

[0043] A comparison of Examples 1-6 with Comparative Example 1 shows that the aqueous in-situ deposition combined with vacuum drying process employed in this invention can obtain halide solid electrolyte membranes with significantly superior performance compared to traditional dry sintering products under mild conditions of 200°C. In particular, Examples 4-6, which introduce cucurbituril, show a significantly higher lithium-ion transport number (t). r It is significantly improved to over 0.80, far exceeding the level of traditional halide electrolytes, and its air stability and cycle stability are also significantly improved.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various improvements and substitutions without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for in-situ preparation of halide electrolyte membrane materials, characterized in that, Includes the following steps: (1) The three-dimensional lithium-ion conductive framework composed of LLZO nanowires is immersed in an aqueous solution containing lithium halide precursor and left to stand at 20~80℃ to allow the halide electrolyte precursor to be deposited in situ in the channels of the three-dimensional lithium-ion conductive framework to obtain a precursor-framework composite. (2) The precursor-skeleton composite is vacuum dried at 200°C to obtain an integrated composite electrolyte membrane.

2. The method for in-situ preparation of halide electrolyte membrane materials according to claim 1, characterized in that, The lithium-containing halide precursors include LiCl and InCl3.

3. The method for in-situ preparation of halide electrolyte membrane materials according to claim 1, characterized in that, The standing time in step (1) is 1.5 to 2.5 hours; the vacuum drying time in step (2) is 3 to 5 hours.

4. The method for in-situ preparation of halide electrolyte membrane materials according to any one of claims 1 to 3, characterized in that, The aqueous solution also contains 0.1-1.5 wt% cucurbita, whose rigid macrocyclic cavity selectively contains Li⁺ and modulates the ion transport pathway.

5. A composite electrolyte membrane, characterized in that, It is prepared by the method for in-situ preparation of halide electrolyte membrane materials according to any one of claims 1 to 4.

6. The composite electrolyte membrane according to claim 5, characterized in that, Its room temperature ionic conductivity is 1.8~2.2 mS·cm －1 Electrochemical window greater than 4.8V, lithium-ion transference number t r ≥ 0.80.

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