Alloy Negative Electrodes for High Energy Density Metal-Ion Cells

The volume expansion behavior and volumetric energy densities of metal alloy negative electrodes (AxM) for metal-ion batteries based on A = Li, Na, K, Mg, Ca and Al are compared. It was found that each metal ion, A, occupies a characteristic volume in alloys which is almost insensitive to the host metal, M. All alloy systems, with the exception of KxM alloys, were found to have similar or greater volumetric energy density than conventional graphitic anodes in Li-ion cells. It is predicted that both the MgxM and AlxM systems might achieve higher energy densities than possible with any Li-ion negative electrode known and operate at potentials at which organic electrolytes are known to be stable.