Flexible free-standing porous graphene/Ni film electrode with enhanced rate capability for lithium-ion batteries

Flexible, lightweight and reliable lithium-ion batteries have attracted tremendous attention and research interest to meet the requirements of portable and bendable devices. Here, flexible, free-standing and porous graphene/Ni film with vertical nano-channels inside is prepared by metal etching of graphene film. Compared with dense graphene film, the porous graphene/Ni film employed as a binder-free anode in lithium-ion batteries exhibits higher capacity and much better rate capability, due to its unique interior channel architecture which is favorable for fast ion transport. At a high current density of 2 A g−1, it can reach a specific capacity of 117 mAh g−1. The porous film also shows low charge transfer resistance and good cycling stability. After 300 cycles at 1 A g−1, its specific capacity still remains at 147 mAh g−1, with high Coulombic efficiency of nearly 100%. Furthermore, the strategy developed here is very simple and of great importance to rational design of porous graphene film or graphene-based hybrids with various applications.