Wang said researchers have, for years, been vexed by the capacity limits associated with traditional lithium battery anodes. Sandia turned to silicon, which offers more than 10 times the lithium capacity potential of graphite.

Sandia researchers acknowledge that the new material has some vulnerabilities. Silicon undergoes a rapid capacity loss during the battery cycling phase. But when small particles of silicon are combined within a graphite matrix, the large capacities are retained. The complete elimination of fading of long-term cycling capacity in the silicon-based electrodes may not be possible, but it can likely be minimized by the design of the carbon-silicon composite microstructure. Still, Wang is confident that the silicon and graphite electrode materials have set the bar for future breakthroughs. "We believe that only other silicon-containing electrode materials can compete with the large capacities that our silicon and graphite composites have demonstrated," says Wang.