A nanosilicon-based composite electrode that can achieve more than 700 cycles at a high capacity of 960 mAh/g of electrode was prepared using aqueous processing in an acidic medium. The buffering of the aqueous solution is mandatory to promote covalent bonding between Si particles and the carboxymethyl cellulose (CMC) binder. The latter is claimed to allow the formation of mechanically stronger contacts within the composite electrode in addition to the CMC bridging of the Si and carbon black particles.