Carbon-Coated All-Solid Battery Cathode
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Solution Overview
Problem
All-solid batteries with sulfide-based solid electrolytes face increased interface resistance due to reactions between the active material and electrolyte, leading to decreased performance, and existing coating methods like mechano-fusion can cause the reaction-inhibiting layers to peel off, further reducing battery efficiency.
Innovation Solution
A positive-electrode active material particle with a reaction-inhibiting layer containing carbon, where the active material core is coated with precursors that inhibit reactions with the sulfide-based solid electrolyte and undergo heat treatment in a high-oxygen atmosphere to form a dense, electronically conductive carbon layer, preventing peeling and enhancing lithium conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sulfide-based solid electrolyte is used in all-solid batteries, then lithium ion conductivity is improved, but interface resistance increases due to reactions between active material and electrolyte
Solution Approach 1:
A reaction-inhibiting layer is introduced as an intermediary between the active material and sulfide-based solid electrolyte. This intermediate layer prevents direct harmful reactions while maintaining lithium ion conductivity, thus reducing interface resistance without sacrificing the high lithium ion conductivity benefit of sulfide-based electrolytes
2Reliability
If the active material is coated with carbon to improve electron conductivity, then electron conductivity is improved, but the reaction-inhibiting layer peels off due to mechanical stress
Solution Approach 1:
The reaction-inhibiting layer and carbon coating are merged into a single integrated layer. This combined layer simultaneously provides reaction inhibition and electron conductivity without the peeling problem, as the carbon is incorporated within the reaction-inhibiting matrix rather than applied as a separate outer coating
Solution Approach 2:
A composite reaction-inhibiting layer is created that combines multiple functional components. The layer integrates reaction inhibition properties with carbon-based electron conductivity, forming a stable composite structure that avoids the delamination issues of separate coatings
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 method effectively prevents interface resistance increases and provides electron conductivity, ensuring stable battery performance by maintaining the reaction-inhibiting layer on the active material surface and promoting lithium ion conductivity.
Implementation Method 1
undergo heat treatment in a high-oxygen atmosphere to form a dense, electronically conductive carbon layer
Implementation Method 2
heat treatment in a high-oxygen atmosphere
Implementation Method 3
reaction-inhibiting layer which contains carbon and with which the active material core is coated... preventing peeling and enhancing lithium conductivity
Implementation Method 4
an interface resistance to the lithium ions that migrate through an interface between the active material and the sulfide-based solid electrolyte
Data Source
AI summary
A positive-electrode active material particle for an all-solid battery which includes a sulfide-based solid electrolyte includes an active material core and a reaction-inhibiting layer which contains carbon and with which the active material core is coated.