Chlorine-Tuned Sulfide Solid Electrolyte for Safer High-Conductivity Cells
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Solution Overview
Problem
Current lithium ion batteries using liquid electrolytes face safety concerns due to flammable organic solvents, and while solid electrolytes offer improved safety, they require higher ion conductivity to compete effectively.
Innovation Solution
A sulfide solid electrolyte comprising lithium, phosphorus, sulfur, and chlorine, with a specific molar ratio of chlorine to phosphorus (Cl/P) greater than 1.0 and 1.9 or less, and an argyrodite-type crystal structure with a lattice constant between 9.750 Å and 9.820 Å, is developed to enhance ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid electrolyte containing flammable organic solvent is used, then the battery can achieve good ion conductivity, but safety concerns arise due to flammability and short circuit risks
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by incorporating chlorine into the sulfide solid electrolyte system with specific molar ratios (0.1 < c(Cl/P) ≤ 1.0), transforming the material properties to achieve both safety and high ion conductivity without flammable organic solvents
Solution Approach 2:
The patent creates a composite solid electrolyte system combining lithium phosphorus sulfide base material with chlorine addition, forming a new composite material (Li-P-S-Cl system) that integrates the advantages of both components to achieve high ion conductivity and safety simultaneously
2Reliability
If a solid electrolyte is used to replace liquid electrolyte, then safety is improved and production cost is reduced, but ion conductivity needs to be enhanced to compete effectively
Solution Approach 1:
The patent optimizes the compositional parameters of the solid electrolyte by controlling the chlorine to phosphorus molar ratio within a specific range (0.1 < c(Cl/P) ≤ 1.0) and adjusting the crystal structure lattice constant (9.700 Å < a ≤ 9.850 Å), thereby enhancing ion conductivity while maintaining the safety advantages of solid electrolytes
Solution Approach 2:
The patent utilizes the crystal structure phase characteristics of the argyrodite-type system, controlling the lattice parameter to achieve optimal ionic conduction pathways through phase structure optimization, enabling high ion conductivity in the solid state
Data Source
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AI summary
The present invention relates to a sulfide solid electrolyte comprising: lithium, phosphorus, sulfur and chlorine, wherein the molar ratio of the chlorine to the phosphorus, c (CI/P), is greater than 1.0 and 1.9 or less, wherein the sulfide solid electrolyte has an argyrodite-type crystal structure, wherein the sulfide solid electrolyte has a peak in each of regions 80.3 to 81.7 ppm, 82.4 to 83.7 ppm and 84.0 to 85.6 ppm in a solid 31P-NMR measurement, wherein an area ratio of the peak in the region of 80.3 to 81.7 ppm to a total area of all peaks in the region of 78 to 92 ppm is 40 % or more.