Active/inactive nanocomposites as anodes for Li-ion batteries

Composites consisting of "active" grains which can alloy with lithium and "inactive" grains which cannot have been made by mechanical alloying of elemental powders. The inactive grains act as a matrix to hold the active grains as they repeatedly alloy with lithium during the operation of a lithium battery. A microscopic mixture of 25% Sn2Fe (active) and 75% SnFe3C (inactive) shows a volumetric capacity for Li which is more than twice that of the graphite materials which are now the anode of choice for the Li-ion battery. Unlike pure Li-Sn and Li-Al alloys, the composite retains this capacity for many charge-discharge cycles suggesting that materials like this will be the anodes of choice for the next generation of compact, high energy, Li-ion batteries. (C) 1998 The Electrochemical Society. S1099-0062(98)07-053-9. All rights reserved.