Disclosed is a material having a composite particle. The composite particle includes an outer shell containing an element such as carbon, nitrogen, oxygen or sulfur and an inner core made from a lithium alloying material such as tin, silicon, aluminum and/or germanium. If the outer shell is made from carbon, the outer shell of the composite particle has an average thickness of less than 20 nanometers and the composite particle has an outer mean diameter of less than 100 nanometers. In some instances, the inner core is made from tin, a tin binary alloy, a tin tertiary alloy or a tin quaternary alloy.
 This invention was made with government support under Contract No. DE-AC52-06NA25396 awarded by the U.S. Department of Energy. The government has certain rights in the invention.