Sulfide Solid Electrolyte Argryrodite Composition
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Solution Overview
Problem
Current lithium ion batteries using liquid electrolytes with flammable organic solvents require safety devices to prevent temperature increases during short circuits, and solid electrolytes with argyrodite crystal structures have high ion conductivity but require improved production methods for mass production and further conductivity enhancement.
Innovation Solution
A sulfide solid electrolyte with an argyrodite-type crystal structure, composed of lithium, phosphorus, sulfur, and one or more halogen or chalcogen elements, with specific molar ratios that enhance ion conductivity, allowing for the formation of a high ion conductivity phase without the need for hydrogen sulfide during heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid electrolyte with flammable organic solvent is used, then ion conductivity is achieved, but safety risk increases requiring additional safety devices
Solution Approach 1:
The patent changes the physical state of the electrolyte from liquid to solid by using a sulfide solid electrolyte with specific composition (Li7-xPS6-yXy where X is halogen or chalcogen element). This parameter change eliminates flammability while maintaining ion conductivity, removing the need for safety devices.
2Reliability
If argyrodite crystal structure sulfide solid electrolyte is used, then ion conductivity is improved, but production method requires improvement for mass production
Solution Approach 1:
The patent optimizes compositional parameters (x and y values in Li7-xPS6-yXy) to achieve the argyrodite crystal structure while enabling mass production. Specific ratios of lithium, phosphorus, sulfur, and halogen/chalcogen elements create a composition that forms the desired crystal structure with high ion conductivity and suitable manufacturing properties.
Solution Approach 2:
The patent creates a composite sulfide solid electrolyte by combining multiple elements (lithium, phosphorus, sulfur, and halogen or chalcogen elements) in specific ratios. This composite material approach achieves both the argyrodite crystal structure for high ion conductivity and improved manufacturability.
3Productivity
If conventional sulfide solid electrolyte production method is used, then production is possible, but sulfur deficiency and unreacted lithium halide occur
Solution Approach 1:
The patent modifies production parameters by optimizing the initial composition ratios of raw materials (Li2S, P2S5, and lithium halide) to account for potential losses during heat treatment. The specific stoichiometric relationships ensure complete reaction without sulfur deficiency or unreacted lithium halide, achieving precise composition control.
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 high ion conductivity, simplifying safety devices and reducing production costs, while avoiding sulfur deficiency and unreacted lithium halide issues, enabling efficient use in lithium ion batteries.
Implementation Method 1
a sulfide solid electrolyte comprising lithium, phosphorus, sulfur and one or more of elements X selected from the group consisting of halogen elements and chalcogen elements excluding sulfur, wherein the sulfide solid electrolyte comprises an argyrodite-type crystal structure
Data Source
AI summary
A sulfide solid electrolyte containing lithium, phosphorus, sulfur; and one or more of elements X selected from the group consisting of halogen elements and chalcogen elements excluding sulfur, wherein the sulfide solid electrolyte includes an argyrodite-type crystal structure, and wherein a molar ratio of the lithium to the phosphorus, a (Li/P), a molar ratio of the sulfur to the phosphorus, b (S/P), and a molar ratio of the element X to the phosphorus, c (X/P), satisfy formulas (1) to (3): 5.0≤a≤7.1 (1) 1.0<a−b≤1.5 (2) 6.5≤a+c<7.1 (3) wherein b>0 and c>0 are satisfied.