Halide-Coated Cathode Material for Low-Overvoltage Solid Batteries
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Solution Overview
Problem
The increase in reaction overvoltage in batteries using halide solid electrolytes containing iodine is a result of oxidative decomposition and continuous electron transfer, leading to poor charge/discharge efficiency and high interfacial resistance.
Innovation Solution
A cathode material configuration with a coating layer of a halide solid electrolyte that does not include iodine, separated from the cathode active material, to suppress oxidative decomposition and electron transfer, using a composition formula LiαMβXγ where M includes metalloid and metal elements other than Li, and X includes Cl and Br, enhancing ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a halide solid electrolyte containing iodine is used, then ion conductivity is improved, but oxidative decomposition occurs leading to increased reaction overvoltage
Solution Approach 1:
The patent introduces an intermediary coating layer comprising a halide solid electrolyte without iodine between the cathode active material and the iodine-containing halide solid electrolyte. This intermediary layer prevents direct contact between the cathode active material and iodine, thereby suppressing oxidative decomposition while maintaining high ion conductivity through the dual-layer structure
2Reliability
If iodine-containing halide solid electrolyte is used, then ion conductivity is enhanced, but electron transfer increases causing high interfacial resistance
Solution Approach 1:
The coating layer acts as a selective intermediary that permits ion transport while blocking electron transfer. The halide solid electrolyte without iodine in the coating layer has appropriate electronic properties that prevent continuous electron transfer to the cathode active material, thereby reducing interfacial resistance while maintaining ion conductivity
3Productivity
If coating layer is added to suppress oxidative decomposition, then charge/discharge efficiency is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by creating a coating layer with specific local properties (halide solid electrolyte without iodine) only at the interface where oxidative decomposition occurs. This localized modification addresses the specific problem area without requiring complete structural redesign, thereby improving charge/discharge efficiency with minimal increase in overall device complexity
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
Suppresses reaction overvoltage, improves charge/discharge efficiency, and maintains high ion conductivity, thereby enhancing battery performance and thermal stability while preventing harmful gas generation.
Implementation Method 1
the first solid electrolyte material includes Li, M, and X... enhances ion conductivity
Implementation Method 2
suppress oxidative decomposition and electron transfer
Data Source
AI summary
Provided is a cathode material including a cathode active material; a coating layer which coats at least a part of a surface of the cathode active material, and which includes a first solid electrolyte material; and a second solid electrolyte material. The first solid electrolyte material includes Li, M, and X; however, does not include sulfur. M includes at least one element selected from the group consisting of metalloid elements and metal elements other than Li. X includes at least one element selected from the group consisting of Cl and Br.