Chloride Solid Electrolyte Composition for Conductivity and Humidity Stability
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Solution Overview
Problem
Existing solid electrolytes, such as Li3YCl6, exhibit high ionic conductivity but low stability due to decomposition in humid environments, necessitating improved stability without compromising conductivity.
Innovation Solution
A solid electrolyte composition containing Li, Zr, Ta, Gd, Cl, and O, with specific molar ratios, achieves high ionic conductivity and stability by incorporating trivalent, quadrivalent, and pentavalent cations, and oxygen, enhancing structural defects for ion mobility and bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chloride electrolytes such as Li3YCl6 are used to achieve high ionic conductivity at ambient temperature, then ionic conductivity is improved, but stability deteriorates due to decomposition in humid environments
Solution Approach 1:
The patent employs composite materials by combining multiple cations (Mα from Zr/Hf, Mβ from Ta/Nb, Mγ from rare earth elements) within the Li2MX6 structure. This composite approach creates a synergistic effect where the different cations contribute to both maintaining high ionic conductivity and enhancing stability against humidity-induced decomposition, resolving the contradiction between conductivity and stability.
Solution Approach 2:
The patent applies parameter changes by systematically varying the composition ratios of different cations (Mα, Mβ, Mγ) in the Li2MX6 structure. By optimizing these compositional parameters, the material achieves a balance where ionic conductivity remains high while stability against decomposition is significantly improved compared to single-cation systems like Li3YCl6.
2Stability of the object's composition
If various cations are combined in Li x MCl 6 to improve stability, then stability is improved, but ionic conductivity fails to constantly achieve sufficient levels
Solution Approach 1:
The patent systematically adjusts compositional parameters by defining specific ranges for cation ratios (0 < a < 1, 0 < b < 1, 0 < c < 1) in the Li6-(4+a-b)(1+c)(Mα(1-a-b)MβaMγb)1+cCl6-2dOd formula. These parameter optimizations ensure that stability is maintained while ionic conductivity remains sufficiently high, overcoming the limitation of previous multi-cation approaches.
Solution Approach 2:
The patent uses a three-component cation composite (Mα, Mβ, Mγ) where each component serves a specific function: Mα (Zr/Hf) provides structural stability, Mβ (Ta/Nb) enhances ionic conductivity pathways, and Mγ (rare earth) improves overall stability. This functional division within the composite resolves the contradiction between stability and conductivity.
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 electrolyte maintains high ionic conductivity and stability in dry room conditions, eliminating the need for heat treatment to recover conductivity, thus reducing production costs and ensuring battery reliability.
Implementation Method 1
Li 3 YCl 6 exhibits high Li ionic conductivity at ambient temperature
Data Source
Figure 1
AI summary
A solid electrolyte contains Li, Mα, Mβ, Mγ, Cl, and O. 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, and Mγ is at least one element selected from the group consisting of Gd, Yb, Dy, Er, Ho, Eu, and Sc. This provides the solid electrolyte with high ionic conductivity and high stability.