TiF-Coated Active Material for Low-Resistance Solid-State Batteries
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Solution Overview
Problem
Conventional batteries with sulfide solid electrolytes face issues of high resistance due to oxidative decomposition during charging, particularly when the solid electrolyte has poor anti-oxidative stability, leading to inefficiencies in energy transfer and battery performance.
Innovation Solution
A coated active material is developed with a coating layer containing Li, Ti, and F, where the proportion of TiF bonds exceeds 2%, providing enhanced oxidation resistance and reducing battery resistance by suppressing oxidative decomposition of the solid electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If sulfide solid electrolyte is used in battery, then ionic conductivity is improved, but oxidation resistance deteriorates leading to high battery resistance
Solution Approach 1:
The patent applies composite materials by combining sulfide solid electrolyte particles with a coating layer containing TiF bonds. The coating layer forms a composite structure on the surface of the sulfide solid electrolyte particles, providing both the high ionic conductivity of the sulfide base material and the oxidation resistance of the TiF-containing coating, thus resolving the contradiction between ionic conductivity and oxidation resistance
Solution Approach 2:
The patent applies local quality by creating a coating layer with specific TiF bond content (more than 2% proportion of TiF bonds) on the surface of the sulfide solid electrolyte particles. This localized modification at the particle surface provides oxidation resistance where it is most needed (at the interface with active material) while maintaining the bulk ionic conductivity properties of the sulfide solid electrolyte
2Reliability
If coating layer with TiF bonds is applied to active material surface, then oxidation resistance is improved, but battery resistance is reduced
Solution Approach 1:
The patent converts the harmful effect of oxidative decomposition into a benefit by using the coating layer to prevent oxidation. The TiF-containing coating layer acts as a protective barrier that prevents the sulfide solid electrolyte from undergoing oxidative decomposition during battery operation, thereby converting the potential harm of oxidation into the beneficial effect of protected, stable battery performance with reduced resistance
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 coated active material significantly reduces battery resistance, improves ionic conductivity, and enhances the durability and charge-discharge efficiency of batteries, even when using sulfide solid electrolytes with poor oxidation resistance.
Implementation Method 1
a proportion of a TiF bond in a group of bonds to the Ti included in the first solid electrolyte is more than 2%... the first solid electrolyte is excellent in oxidation resistance
Data Source
AI summary
A coated active material of the present disclosure includes: an active material; and a coating layer including a first solid electrolyte, the coating layer coating at least a portion of a surface of the active material. The first solid electrolyte includes Li, Ti, M, and F, the M is at least one selected from the group consisting of Ca, Mg, Al, Y, and Zr, and a proportion of a TiF bond in a group of bonds to the Ti included in the first solid electrolyte is more than 2%.