Sulfide Solid Electrolyte Composition for Moisture-Reversible Conductivity
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Solution Overview
Problem
Sulfide solid electrolytes have low water resistance and react with moisture in the air, leading to decreased ionic conductivity that is not fully recovered even after drying.
Innovation Solution
A sulfide solid electrolyte with a crystal structure containing divalent elements, halogen elements, and nitrogen, where the combination of divalent and halogen elements has higher hydration energy than LiI, improving the reversibility of hydration reactions and recovery rate of ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sulfide solid electrolyte is used as a nonaqueous electrolyte, then high energy density and improved safety are achieved, but the ionic conductivity decreases when exposed to moisture in the air
Solution Approach 1:
The invention changes the chemical composition parameters of the sulfide solid electrolyte by incorporating specific divalent elements (Ca, Sr, Ba, Mn, Zn, Cu) and halogen elements (F, Cl, Br, I) in controlled ratios. This compositional modification alters the material's hydration characteristics, enabling it to resist moisture-induced conductivity degradation while maintaining high ionic conductivity in the dry state
Solution Approach 2:
The invention creates a composite sulfide solid electrolyte system by combining multiple elements (divalent elements, halogen elements, sulfur, and optionally lithium and phosphorus) into a unified material structure. This composite approach leverages the synergistic effects of different elements to achieve both high ionic conductivity and improved water resistance simultaneously
2Reliability
If the sulfide solid electrolyte is left in a dry air atmosphere, then it reacts with moisture and ionic conductivity decreases, but drying again does not sufficiently recover the ionic conductivity
Solution Approach 1:
The invention modifies the hydration thermodynamics by selecting divalent element and halogen element combinations with specific hydration energy characteristics. This parameter optimization ensures that hydration reactions are highly reversible, allowing the material to regain its original ionic conductivity state after drying following moisture exposure
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
The sulfide solid electrolyte achieves a high recovery rate of ionic conductivity upon drying, enhancing its performance and stability in humid environments.
Implementation Method 1
the sulfide solid electrolyte reacts with the moisture contained in a minute amount in the dry air
Implementation Method 2
even when the sulfide solid electrolyte is dried again
Data Source
AI summary
A sulfide solid electrolyte according to an aspect of the present invention includes a crystal structure and contains, as constituent elements, one, or two or more divalent elements A, one, or two or more halogen elements X, and a nitrogen element, and the divalent element A and the halogen element X make a combination such that a compound A0.5X composed of the divalent element A and the halogen element X is higher in hydration energy than LiI.