Sulfide Solid Electrolyte Drying via LiOH Mediator
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Solution Overview
Problem
The high deliquescency of LiI requires high temperatures for drying, and adding large amounts of LiOH to increase drying temperature to 200°C or less results in a decrease in lithium halide concentration, posing a challenge in producing sulfide solid electrolyte materials effectively.
Innovation Solution
A method involving a precursor aqueous solution with a molar ratio of LiOH to (LiI + LiBr) of 3 or more but less than 6, allowing LiI, LiBr, and LiOH to coexist during drying, which increases lithium halide concentration and enables drying at 200°C or less, involving a sulfidization treatment to convert LiOH to LiHS, followed by de-sulfide-hydrogenating treatment to obtain Li2S, and reacting it with an auxiliary material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LiI is dried at a high temperature to remove water, then drying efficiency is improved, but energy consumption increases and material decomposition risk increases
Solution Approach 1:
LiOH acts as an intermediary substance that facilitates water removal from LiI at lower temperatures. The LiOH forms a hydrate complex with water molecules, enabling drying at 200°C or less instead of requiring high temperatures. This mediator approach resolves the contradiction by providing an alternative drying mechanism that consumes less energy while maintaining drying efficiency.
Solution Approach 2:
The invention changes the chemical composition parameters of the precursor aqueous solution by controlling the molar ratio of LiOH to (LiI + LiBr) to be 3 or more and less than 6. This parameter optimization enables low-temperature drying while preventing material decomposition, thus resolving the contradiction between drying efficiency and energy consumption.
2Temperature
If a large amount of LiOH is added to LiI to enable low-temperature drying, then drying temperature is reduced, but lithium halide concentration decreases
Solution Approach 1:
The invention optimizes the molar ratio parameter of LiOH to (LiI + LiBr) within the specific range of 3 or more and less than 6. This precise parameter control allows sufficient LiOH to be present for low-temperature drying while preventing excessive LiOH from diluting the lithium halide concentration too much, thus resolving the contradiction between temperature reduction and concentration maintenance.
Solution Approach 2:
The invention uses a controlled amount of LiOH that is sufficient for low-temperature drying but not excessive. By limiting the LiOH ratio to less than 6, the invention achieves partial action - enough LiOH to enable low-temperature drying while avoiding the harmful effect of excessive LiOH that would overly dilute the lithium halide concentration.
3Reliability
If LiI and LiBr are used together in the precursor aqueous solution, then the stability of the electrolyte material is improved, but the complexity of the production process increases
Solution Approach 1:
The invention merges LiI and LiBr into a single precursor aqueous solution with a controlled molar ratio, allowing both halides to coexist and contribute to electrolyte stability. This combining approach maintains reliability while simplifying the process compared to separate treatments, as both materials are processed simultaneously in one drying and sulfidization cycle.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enhances lithium halide concentration and allows for low-temperature drying, potentially increasing the Li ion conductivity of the sulfide solid electrolyte material, facilitating its production with improved efficiency.
Implementation Method 1
addition of 6 times of LiOH to LiI in the molar basis allows drying at a low temperature (such as 200° C. or less)
Implementation Method 2
conducting a sulfidization treatment, a de-sulfide-hydrogenating treatment, and a synthesizing treatment
Data Source
AI summary
A main object of the present disclosure is to provide a method for producing a sulfide solid electrolyte material, the method that allows a concentration of lithium halide to increase and that allows drying at a low temperature. The present disclosure achieves the object by providing a method for producing a sulfide solid electrolyte material, the method comprising: a drying step of drying a precursor aqueous solution containing LiI, LiBr, and LiOH to remove water and obtain a precursor mixture; and an electrolyte synthesizing step including a sulfidization treatment to sulfurize the LiOH in the precursor mixture and obtain LiHS, a de-sulfide-hydrogenating treatment to desorb a hydrogen sulfide from the LiHS and obtain Li2S, and a synthesizing treatment to make the Li2S to react with an auxiliary material; wherein a molar ratio of the LiOH with respect to the LiI and the LiBr, LiOH/(LiI+LiBr), in the precursor aqueous solution is 3 or more and less than 6.