Sulfide Solid Electrolyte Composition for Safe Lithium Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithium batteries rely on flammable organic solvents in their electrolytes, posing safety risks and requiring complex safety devices, while all-solid-state batteries with sulfide solid electrolytes aim to simplify safety but often have high lithium content and stability issues.
Innovation Solution
A sulfide solid electrolyte material with a composition of (Li2S)x(MS2)y(P2S5)z, where M is Ge, Sb, Si, Sn, B, Al, Ga, In, Zr, or Nb, and 0.53≤x≤0.74, 0.13≤y≤0.37, 0.04≤z≤0.15, exhibiting favorable Li ion conductivity and stability, and an argyrodite type structure stable at room temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flammable organic solvents are used in electrolytes to achieve high ion conductivity, then ion conductivity is improved, but safety deteriorates due to fire hazards and requirement for complex safety devices
Solution Approach 1:
The invention changes the physical state parameter of the electrolyte from liquid (organic solvent) to solid (sulfide-based solid electrolyte), thereby eliminating flammability while maintaining ion conductivity through compositional optimization of Li2S-MS2-P2S5 system
Solution Approach 2:
The invention uses composite material strategy by combining Li2S, MS2 (M=Ge, Sb, Si, Sn, B, Al, Ga, In, Zr, or Nb), and P2S5 in specific ratios to create a solid electrolyte that achieves both high ion conductivity and intrinsic safety without flammable components
2Reliability
If Li4GeS4 and Li3PS4 solid-solution systems are used to achieve high Li ion conductivity, then ion conductivity is improved, but lithium content becomes excessively high which affects stability
Solution Approach 1:
The invention optimizes the compositional parameters by controlling the ratios of Li2S (x), MS2 (y), and P2S5 (z) within specific ranges, achieving a balance between lithium content and structural stability, and stabilizing the argyrodite type structure at room temperature
Solution Approach 2:
The invention introduces different M elements (Ge, Sb, Si, Sn, B, Al, Ga, In, Zr, Nb) that can be selectively positioned in the crystal structure to locally optimize both ion conductivity pathways and structural stability, allowing different regions of the crystal to fulfill different functional requirements
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 material achieves lower lithium content, improved stability, and high ion conductivity, enabling the development of safer and more efficient lithium batteries with reduced production costs.
Implementation Method 1
a sulfide-based solid electrolyte which exhibits favorable Li ion conductivity
Data Source
AI summary
(Problem to be Solved) A solid electrolyte material with favorable ion conductivity is demanded from the viewpoint of the higher output of a battery. The present invention was made in view of the above-described problems, with an object of providing a sulfide solid electrolyte material with favorable Li ion conductivity and providing a lithium battery including the sulfide solid electrolyte material. (Solution) There are provided: a solid electrolyte including a sulfide-based solid electrolyte represented by a composition formula: (Li2S)x(MS2)y(P2S5)z, in which M is at least one selected from the group consisting of Ge, Sb, Si, Sn, B, Al, Ga, In, Zr, V, and Nb, and 0.53≤x≤0.74, 0.13≤y≤0.37, 0.04≤z≤0.15, and x+y+z=1 are satisfied; and a lithium battery including the solid electrolyte.