Alloy Negative Electrodes for High Energy Density Metal-Ion Cells

The volume expansion behavior and volumetric energy densities of metal alloy negative electrodes (A x M) 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 K x M 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 Mg x M and Al x M 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.