Electrochemical behavior of elemental alloy anodes in solid-state batteries

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Dense lithium alloy anodes are promising for solid-state batteries (SSBs) but their reaction mechanisms are poorly understood.
• Current research lacks direct comparisons of various alloy anodes in SSBs.

Purpose of the Study:

• To investigate the electrochemical lithiation/delithiation behavior of 12 elemental alloy anodes in SSBs.
• To identify the key factors influencing Coulombic efficiency in dense alloy anodes.

Main Methods:

• Electrochemical testing of 12 elemental alloy anodes with Li6PS5Cl solid-state electrolyte.
• Microstructural imaging to analyze reaction and degradation mechanisms.

Main Results:

• Observed highly divergent first-cycle Coulombic efficiency, from ~20% for antimony to 99.3% for indium.
• Identified lithium trapping during delithiation as a primary cause of low Coulombic efficiency for most alloys.
• Indium's superior performance is attributed to a unique delithiation front morphology enabling sustained LiIn phase at the electrolyte interface.

Conclusions:

• Alloy composition significantly impacts reaction behavior and Coulombic efficiency in SSBs.
• Understanding delithiation mechanisms is crucial for designing high-performance alloy anodes.
• Indium's behavior provides a model for developing advanced alloy anodes for next-generation solid-state batteries.