Coated Sulfide Solid Electrolyte for Moisture-Stable Solid-State Batteries
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Solution Overview
Problem
The Li ion conductivity of sulfide solid electrolytes in solid state batteries is easily degraded by moisture, leading to battery deterioration.
Innovation Solution
A solid state battery design that incorporates a coated sulfide solid electrolyte with a modifier, where the cathode, anode, and solid electrolyte layers contain the coated sulfide solid electrolyte, and the modifier is a compound represented by specific general formulas or their polymers, with a modifier proportion of 12.5 mass % or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a sulfide solid electrolyte is used in a solid state battery, then high Li ion conductivity is achieved, but the battery is easily deteriorated by moisture
Solution Approach 1:
The patent applies composite materials by combining sulfide solid electrolyte particles with a coating layer containing modifier compounds (epoxy compounds, silane compounds, or their polymers). This composite structure maintains the high Li ion conductivity of the sulfide core while the coating layer provides moisture resistance, resolving the contradiction between conductivity and moisture stability
Solution Approach 2:
The patent uses a thin coating layer (1-100 nm thickness) formed on the surface of sulfide solid electrolyte particles. This flexible thin film approach provides effective moisture protection while minimizing impact on ion conductivity and maintaining the structural integrity of the electrolyte particles
2Reliability
If a coating layer with modifier is applied on sulfide solid electrolyte, then moisture resistance is improved, but production cost increases
Solution Approach 1:
The patent optimizes the modifier proportion parameter to 1-12.5 mass% (preferably 1-10 mass%) relative to the sulfide solid electrolyte. This parameter control ensures sufficient moisture resistance while avoiding excessive modifier usage that would increase production costs, achieving a cost-effective balance
Solution Approach 2:
The patent applies the coating layer selectively on the surface of sulfide solid electrolyte particles rather than throughout the entire electrolyte structure. This localized application provides moisture protection exactly where needed (at the particle surfaces exposed to moisture) while minimizing the total amount of expensive modifier material required
Data Source
AI summary
A solid state battery includes a cathode active material layer, an anode active material layer, and a solid electrolyte layer arranged between the cathode active material layer and the anode active material layer, wherein the cathode active material layer, the anode active material layer, and the solid electrolyte layer contain a coated sulfide solid electrolyte as an electrolyte; the coated sulfide solid electrolyte includes a sulfide solid electrolyte containing at least a Li element, a S element, and a P element, and a coating layer that covers a surface of the sulfide solid electrolyte and contains a modifier; and the modifier is at least one kind of, a compound represented by the general formula (1), a compound represented by the general formula (2), a polymer of the compound represented by the general formula (1), and a polymer of the compound represented by the general formula (2).