Lithium insertion into Sn and SnSb x metallic hosts and the subsequent cycling behavior in polyethylene oxide (PEO)-based polymer electrolytes are examined. Inserted lithium can hardly be extracted from the electrode constituted by coarse tin powder due to the electrical isolation after dramatic host volume changes. Decreasing the host particle size and using intermetallic SnSb x alloy powders greatly enhance the electrode Li extraction capacity and its retention on cycling. The high irreversible capacity in the first cycle linked to the use of ultrafine host powders is compensated by introducing a certain amount of Li2.6Co0.4N into the electrode. Some factors influencing the cell performance are presented and discussed.