Carbon-coated, carbon nanotube (CNT)/tin(oxide) spongy coaxial nanostructures, CNT/Sn(O(2))@C, with large areal mass loadings have been developed by employing a three-dimensional CNT sponge as a backbone. The freestanding spongy coaxial nano-architecture demonstrates exceptional electrochemical characteristics of tin-based anode materials with appropriate structural engineering for energy storage application.