Tandem structure of porous silicon film on single-walled carbon nanotube macrofilms for lithium-ion battery applications.

Development of materials and structures leading to high energy and power density lithium-ion batteries is a major challenge to the power needs of the electronic and automobile industries. Silicon is an attractive anode material being closely scrutinized for use in lithium-ion batteries but suffers from a poor cyclability and early capacity fading. In this work, we present a tandem structure of porous silicon film on single-walled carbon nanotube (SWNT) film to significantly improve the cycling stability of silicon as lithium-ion battery anode material. With this new structure configuration of the silicon films, a reversible specific capacity of 2221 mAh/g was retained after 40 charge-discharge cycles at 0.1 C rate, which is 3.6 times that of silicon film on a regular copper substrate and more than 11 times that of the SWNT film. The facile method is efficient and effective in improving specific capacity and stability of silicon anode lithium-ion batteries and will provide a powerful means for the development of lithium-ion batteries.