Sulfide Solid Electrolyte Particles with Oxidized Surface Layer
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Solution Overview
Problem
Sulfide solid electrolyte materials in all-solid-state batteries face challenges with low ion conductivity and insufficient suppression of hydrogen sulfide generation, particularly when the Li/P molar ratio exceeds 3, leading to high interface resistance and limited practical use.
Innovation Solution
Sulfide solid electrolyte particles comprising Li, P, S, and a halogen with a specific oxygen/sulfur element ratio range on the surface and at a depth of 30 nm, achieved through exposure to a controlled water concentration atmosphere followed by drying, to enhance ion conductivity while suppressing hydrogen sulfide generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Li/P molar ratio is increased to improve ion conductivity, then ion conductivity is improved, but hydrogen sulfide generation increases and interface resistance increases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core maintains high Li/P molar ratio for ion conductivity while the outer shell has modified composition to suppress hydrogen sulfide generation. Specifically, the sulfide solid electrolyte particle has a core region with Li/P > 3 and an outer layer with different oxygen/sulfur ratios that prevents H2S emission while maintaining overall high ion conductivity.
Solution Approach 2:
The patent uses composite materials by combining sulfide solid electrolyte with controlled oxygen and sulfur distribution. The composite structure includes regions with different oxygen/sulfur element ratios, creating a multi-phase material that simultaneously achieves high ion conductivity (from sulfide-rich core) and low hydrogen sulfide generation (from oxidized outer layer).
2Object-generated harmful factors
If the oxygen/sulfur element ratio on the surface is increased to suppress hydrogen sulfide generation, then hydrogen sulfide generation is suppressed, but ion conductivity decreases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core maintains high Li/P molar ratio for ion conductivity while the outer shell has modified composition to suppress hydrogen sulfide generation. Specifically, the sulfide solid electrolyte particle has a core region with Li/P > 3 and an outer layer with different oxygen/sulfur ratios that prevents H2S emission while maintaining overall high ion conductivity.
Solution Approach 2:
The patent uses partial action by applying oxidation treatment only to the outer surface layer rather than the entire particle. The oxygen/sulfur ratio is controlled to be 0.5 or more at the surface (to suppress H2S) while maintaining lower ratios in the bulk (to preserve ion conductivity). This partial modification achieves both goals without excessive oxidation that would harm overall performance.
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 approach results in sulfide solid electrolyte particles with improved ion conductivity and reduced hydrogen sulfide generation, enabling higher charge/discharge rates and increased durability in all-solid-state batteries.
Implementation Method 1
the oxide layer resulting from the oxidation of the particle itself
Data Source
AI summary
Provided are sulfide solid electrolyte particles which have sufficient ion conductivity and which are configured to suppress hydrogen sulfide generation, and an all-solid-state battery comprising the sulfide solid electrolyte particles. Disclosed are sulfide solid electrolyte particles comprising Li, P, S and a halogen as constituent elements and having a Li/P molar ratio of more than 3, wherein an oxygen/sulfur element ratio of a particle surface measured by XPS is 0.29 or more and 0.81 and less, and an oxygen/sulfur element ratio at a depth of 30 nm (in terms of a SiO2 sputter rate) from the particle surface measured by XPS, is 0.29 or less.