Abstract: A novel hybrid lithium-ion anode material based on coaxially coated Si shells on carbon nanofibers (CNF). The unique cup-stacking graphitic microstructure makes the CNFs an effective Li+ intercalation medium. Highly reversible Li+ intercalation and extraction were observed at high power rates. More importantly, the highly conductive and mechanically stable CNF core optionally supports a coaxially coated amorphous Si shell which has much higher theoretical specific capacity by forming fully lithiated alloy. Addition of surface effect dominant sites in close proximity to the intercalation medium results in a hybrid device that includes advantages of both batteries and capacitors.