posted on 2024-01-26, 14:04authored byJack Aspinall, Yvonne Chart, Hua Guo, Pranay Shrestha, Matthew Burton, Mauro Pasta
Indium–lithium
alloys operating in the two-phase region
of indium metal and the InLi intermetallic are the counter and reference
electrodes of choice in two-electrode solid-state batteries. At high
current densities on both charge and discharge, they offer low polarization,
good accessible capacity, and good cycle life. By synthesizing a phase
pure InLi intermetallic and measuring its diffusion and mechanical
properties, it is clear that the electrochemical performance is attributable
to measured fast diffusion kinetics in the InLi intermetallic, DLi298K = 5.5 × 10–7 cm2 s–1. The indium metal phase is essentially ion-blocking, so the performance
is tied to the microstructure, which evolves with cycling. A simple
two-layer microstructure is proposed, based on the fundamental understanding
established, which maximizes performance. Despite the limitations
of indium-based alloys in commercial applications, the lessons learned
can be extended to other fast-conducting lithium intermetallics.