Abstract: Electrolytes are described that involve lithium salt blends and compatible nonaqueous solvents that provide to high rate performance, charging and discharging, of lithium ion cells using silicon-based active materials, such as silicon suboxide composites, for example, silicon oxide/silicon/carbon composites. The lithium salts generally were a blend of LiPF6, and LiFSI or LiTFSI. The solvents generally comprised fluoroethylene carbonate and dimethyl carbonate with optional cosolvents and/or other additives.