Coaxial carbon-silicon-carbon nanotube arrays in porous anodic aluminum oxide templates as anodes for lithium ion batteries

Silicon is a promising anode material for lithium ion batteries because of its low discharge potential and high theoretical charge capacity (4200 mA h g(-1)). However, the poor cycle performance, which arises from the large volume change upon the insertion and extraction of lithium ions, has limited its application. Here, we introduce a composite structure of coaxial carbon-silicon-carbon nanotube arrays in a porous anodic aluminium oxide membrane as a high-capacity and long-life anode. The carbon layer can not only protect silicon from generating a solid electrolyte interphase, but can also function as the current collector. These anode materials have a high first Coulombic efficiency of 90% and high specific capacities (similar to 4000 mA h g(-1) for silicon and more than 600 mA h g(-1) for the whole anode). Significantly, using these composite structures we have obtained an area capacity of similar to 6 mA h cm(-2), which is larger than commercial graphite anode values.