Alloy Anodes for Solid-State Batteries

The serious challenges of utilizing Li metal anodes with solid electrolytes have motivated the research on alternative anodes. Alloy-based anodes have been gaining great interest recently due to their high capacities. Nevertheless, the utilization of alloy anodes cannot prevent Li plating and subsequent cell shorting. In this presentation, we aim to provide our initial understanding of the dendrite formation in alloy-based solid-state batteries by evaluating the dendrite suppression capability of commonly Li alloys including Li-Zn, Li-Si, Li-Sn, and Li-Al. Our results indicate that Li-Al outperforms other alloys in preventing cell shorting. A possible mechanism for the superior performance of Li-Al based on its mechanical properties will also be introduced. While the slightly higher potential of alloy anodes helps to improve the interfacial stability with solid electrolytes, our recent results show that apparent decomposition of thiophosphate-based solid electrolytes occurs when used with Si anodes. The decomposition of solid electrolytes not only leads to a decrease in the first cycle coulombic efficiency which can complicate cell balancing, but also affects the reaction mechanisms in the subsequent cycles. The utilization of cathodic stable electrolytes, for example, hydrides, is therefore important for alloy anodes. Our work highlights that the properties of both the alloy itself and the solid electrolyte should be carefully studied for the future development of alloy anodes for solid-state batteries.