Effect of microstructure on the cycling behaviour of Li-In alloy anodes for solid-state batteries
In this paper* published by ACS Energy Letters, a team of researchers from the Pasta Group reviewed how indium-lithium alloys operate in the two-phase region of indium metal and the InLi intermetallic as counter and reference electrodes of choice in two-electrode solid-state batteries.
At high current densities on both charge and discharge, they offer low polarisation, good accessible capacity and a good cycle life. By synthesising 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 maximises performance.
Despite the limitations of indium-based alloys in commercial applications, the lessons learned can be extended to other fast-conducting lithium intermetallics.
*Effect of microstructure on the cycling behaviour of Li-In alloy anodes for solid-state batteries'.
