Halide Solid Electrolyte Lattice Expansion for Battery Safety
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Solution Overview
Problem
Existing solid electrolyte materials for batteries often have limitations in lithium-ion conductivity and safety, particularly due to the generation of hydrogen sulfide, which can compromise battery performance and safety.
Innovation Solution
A solid electrolyte material composed of Li, M (metallic elements), and X (Cl, Br, or I) with a sublattice structure that is 1.8% or more expanded compared to a rock-salt structure, promoting high lithium-ion conductivity and eliminating sulfur, thus preventing hydrogen sulfide generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfide solid electrolyte materials are used in batteries, then lithium-ion conductivity can be achieved, but hydrogen sulfide is generated compromising safety
Solution Approach 1:
The patent changes the chemical composition parameters by replacing sulfur-based electrolytes with halide-based electrolytes (Li3YCl6, Li3YBr6, or their solid solutions). This fundamental parameter change eliminates the harmful hydrogen sulfide generation while maintaining high lithium-ion conductivity through the halide ion conduction mechanism.
Solution Approach 2:
The patent employs composite material design by creating solid solution electrolytes that combine Li3YCl6 and Li3YBr6 in various ratios. This composite approach allows optimization of both ionic conductivity and structural stability, achieving high performance without the harmful effects of sulfide materials.
2Device complexity
If rock-salt structure is used for Li and X, then structural simplicity is maintained, but lithium-ion conductivity is limited
Solution Approach 1:
The patent modifies the structural parameter by expanding the lattice constant of the rock-salt structure. By increasing the distance between adjacent X atoms to 1.8% or more compared to the standard rock-salt structure, the material achieves higher lithium-ion conductivity while retaining the structural simplicity and stability of the rock-salt framework.
3Reliability
If lattice expansion of 1.8% or more is achieved, then lithium-ion conductivity increases to 1×10−4 S/cm or more, but structural deviation from rock-salt increases
Solution Approach 1:
The patent optimizes the lattice expansion parameter within a specific range (1.8% or more but maintaining rock-salt framework). This controlled parameter change achieves the threshold for high conductivity (1×10−4 S/cm or more) while preserving the fundamental structural stability needed for practical battery applications.
Solution Approach 2:
The patent uses composite solid solutions of Li3YCl6 and Li3YBr6 to achieve the desired lattice expansion. The composite structure allows fine-tuning of the lattice constant through composition control, enabling simultaneous achievement of high conductivity and structural stability.
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 material achieves high lithium-ion conductivity of 1×10−4 S/cm or more, ensuring good charge/discharge characteristics and enhanced safety by avoiding hydrogen sulfide generation, while maintaining stability and efficiency in battery operations.
Implementation Method 1
a solid electrolyte material having a high lithium-ion conductivity
Data Source
AI summary
A solid electrolyte material contains Li, M, and X. M is at least one selected from metallic elements, and X is at least one selected from the group consisting of Cl, Br, and I. A plurality of atoms of X form a sublattice having a closest packed structure. An average distance between two adjacent atoms of X among the plurality of atoms of X is 1.8% or more larger than a distance between two adjacent atoms of X in a rock-salt structure composed only of Li and X.