PROCESSES TO FABRICATE POROUS SILICON AND ITS USE AS FEEDSTOCK FOR SECONDARY BATTERY ELECTRODES

Provided are processes to form microporous silicon useful as an active material in an electrode of an electrochemical cell the processes including subjecting a mixture of silicon oxide and a metal reducing agent, optionally aluminum, to mechanical milling to form mechanically activated silicon oxide/aluminum, thermally treating the silicon oxide/aluminum to reduce the silicon oxide and form Si/AlO, and removing at least a portion of the alumina from the Si to form a microporous silicon. The resulting electrochemically active microporous silicon is also provided with residual alumina present at 15% by weight or less that demonstrates excellent cycle life and safety.