Communication—Solid-State Synthesis of Lithium Silicide

Abstract

Lithium silicide (Li-Si) compounds were synthesized by a reaction between ball-milled commercially available micron sized precursor powders of lithium hydride and silicon. The reaction occurs at ≤500 °C, with the composition controlled by the LiH-to-Si ratio. The products are crystalline equilibrium phases found in the Li-Si phase diagram. The synthesized Li-Si material has a particle size akin to that in the precursor Si, thus eliminating the need for attrition processing before electrode fabrication. Furthermore, the crack-free Li-Si particles may reduce gassing and improve capacity retention in cells. Synthesized Li-Si was also found to be relatively stable during handling in ambient air.

Lessons Learned─Lithium Silicide Hydration Fire

“…Lithium silicide is a complicated alloy, but generally, the various phases are more stable than pure lithium metal . However, lithium silicide is pyrophoric like lithium metal, with its reaction with water being extremely exothermic, , autoigniting the hydrogen gas produced when the temperature reaches 585 °C or, in some cases, the metal alloy itself (the temperature at which this occurs varies depending on the environment), resulting in an explosion and subsequent fire (example lithium silicide ignition, Figure ).…”