Halide Solid Electrolyte Composition for Dry-Stable Ion Conductivity
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Solution Overview
Problem
Existing solid electrolytes, such as those containing halides like Li3YCl6 and Na2ZrCl6, exhibit low stability when exposed to dry environments, leading to a reduction in lithium-ion or sodium-ion conductivity.
Innovation Solution
A solid electrolyte composition comprising Li, Na, Zr, Ta, Gd, Yb, and Cl, with specific molar ratios and ionic radius ratios, that achieves high ion conductivity and stability by avoiding the decomposition commonly seen in halide-based electrolytes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If halide-based solid electrolytes (e.g., Li3YCl6, Na2ZrCl6) are used to achieve high ion conductivity at ambient temperature, then lithium-ion or sodium-ion conductivity is improved, but stability deteriorates when exposed to dry environments
Solution Approach 1:
The patent uses a composite material system combining oxide and halide components. The oxide matrix (e.g., Li2SiO3, Li2GeO3) provides structural stability and resistance to decomposition in dry environments, while the halide component (e.g., ZrCl6 2-, TaCl6 2-) contributes to high ion conductivity. This composite structure allows the electrolyte to maintain both high reliability and stability simultaneously.
Solution Approach 2:
The patent modifies the chemical composition parameters by introducing multiple cations (Li, Na, Zr, Hf, Ta, Nb, Gd, Yb, Dy, Er, Ho, Eu, Sc) and controlling their molar ratios. Specifically, the chloride-to-alkali metal ratio is optimized (Cl > A in molar amount), and the average ionic radius ratio is controlled (<0.424 for Li, <0.526 for Na). These parameter changes enable the material to achieve both high ion conductivity and environmental stability.
2Stability of the object's composition
If chloride electrolyte powder is prepared and rested in a dry room (dew point -40°C) to maintain stability, then decomposition is prevented, but initial lithium-ion conductivity is lost
Solution Approach 1:
The patent identifies and controls critical composition parameters: the molar ratio of Cl to A (where Cl > A), and the average ionic radius ratio of cations to chloride (<0.424 for Li, <0.526 for Na). By optimizing these parameters, the electrolyte achieves intrinsic stability that does not require aggressive dry storage conditions, thereby maintaining both stability and conductivity.
Solution Approach 2:
The oxide-halide composite structure creates a more stable crystal lattice that is resistant to decomposition even in less stringent environmental conditions. The oxide component provides structural rigidity and chemical stability, allowing the material to maintain its conductivity properties without requiring dew point -40°C storage, thus resolving the contradiction between stability and conductivity retention.
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 proposed solid electrolyte maintains high ion conductivity and stability, even after exposure to dry conditions, thereby enhancing the reliability and safety of all-solid-state batteries.
Implementation Method 1
Li 3 YCl 6 exhibits high lithium-ion conductivity at ambient temperature
Data Source
Figure 1
AI summary
A solid electrolyte contains A, Mα, Mβ, Mγ, and Cl, wherein A is at least one element selected from the group consisting of Li and Na, Mα is at least one element selected from the group consisting of Zr and Hf, Mβ is at least one element selected from the group consisting of Ta and Nb, Mγ is at least one element selected from the group consisting of Gd, Yb, Dy, Er, Ho, Eu, and Sc, and the amount of substance of Cl is greater than the amount of substance of A. Accordingly, it is possible to provide the solid electrolyte with high ion conductivity and high stability.