Solid-State Battery Design: Solving Ion Conduction Path Issues
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Summary
Problems
Conventional solid-state batteries using high-capacity negative electrode active materials with large volume changes and sulfide-based solid electrolytes face issues with ion conduction path disappearance due to charge-discharge cycles, leading to capacity degradation, and existing solutions like binders and ionic liquids either increase resistance or react negatively with sulfide-based electrolytes.
Innovation solutions
A negative electrode composite material comprising a silicon-based active material, a sulfide-based solid electrolyte, and a specific ionic liquid with an anion donor number of 9 or less, such as BMPTFSI, is used to maintain ion conduction paths, suppressing capacity loss during charge-discharge cycles.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If a high-capacity negative electrode active material with large volume change ratio is used, then battery capacity is improved, but ion conduction path disappears due to repeated volume changes, leading to capacity degradation
Why choose this principle:
The invention changes the physical state of the electrolyte from solid to liquid (or gel-like) to enable the electrolyte to dynamically adapt to volume changes. The liquid/gel electrolyte can flow and deform to maintain contact with the active material surface during expansion and contraction, preserving ion conduction paths throughout charge-discharge cycles.
Principle concept:
If a high-capacity negative electrode active material with large volume change ratio is used, then battery capacity is improved, but ion conduction path disappears due to repeated volume changes, leading to capacity degradation
Why choose this principle:
The liquid or gel electrolyte acts as an intermediary between the solid electrodes and provides a flexible ion conduction medium. This intermediary can accommodate volume changes better than solid electrolytes, maintaining continuous ion transport pathways even when electrode dimensions change during cycling.
Application Domain
Data Source
AI summary:
A negative electrode composite material comprising a silicon-based active material, a sulfide-based solid electrolyte, and a specific ionic liquid with an anion donor number of 9 or less, such as BMPTFSI, is used to maintain ion conduction paths, suppressing capacity loss during charge-discharge cycles.
Abstract
To blend a specific ionic liquid in the negative electrode composite material. Specifically, the negative electrode composite material includes a negative electrode active material, a solid electrolyte, and an ionic liquid, wherein the negative electrode active material is a silicon-based negative electrode active material, the solid electrolyte is a sulfide-based solid electrolyte, and the ionic liquid includes an anion having a donor number of 9 or less as determined from a half-wave potential of a noble metal.