Hydrogen treated, cap-opened Si nanotubes array anode for high power lithium ion battery

Silicon is a promising anode material for lithium ion batteries due to its low discharge potential and high theoretical capacity. However, rapid capacity fading caused by large volume change during cycling and poor rate capability came from low lithium ion diffusivity limit its practical use. Here, we report a novel approach to provide higher accessibility of lithium ions to the Si surface and shorter lithium ion diffusion length in Si nanotube structures. Its tubular geometry and large surface area enable effective accommodation of large volume change and large lithium ion flux at the interface between Si and electrolyte, respectively. Hydrogen treated, cap-opened Si nanotubes electrode shows excellent rate capability. The proposed electrode geometry provides a significant new insight into designing high power anode materials for the advanced lithium ion batteries.