Synthesis of Highly-Ordered Two-Dimensional Hierarchically Porous Carbon Nanosheet Stacks as Advanced Electrode Materials for Lithium-Ion Storage

Highly ordered, hierarchically porous and interlinked carbon nanosheet stacks are explored via an intercalation reaction into the layered TiO2 template. Herein, benzidine is used as the raw material to produce carbon nanosheet stacks through polymerization and carbonization, followed by a wet-chemical etching to remove the template. The oriented nanosheet structures can provide accessible electrochemical channels for ion diffusion, while the interconnected interlayer can also maintain high electronic conductivity and fast electron transfer, thus resulting in a remarkable rate performance. Typically, a high specific capacity of 681.2 mA h g-1 can be delivered by the as-prepared carbon nanosheets at 0.1 A g-1, and 120.0 mA h g-1 is still maintained at a high current of 12.8 A g-1. Meanwhile, a specific capacity of 100 mA h g-1 remains over 7000 charge/discharge cycles at 3 A g-1. The outstanding rate performance and cycle stability of carbon nanosheets are ascribed to the hierarchical and oriented nanosheet structure with high porosity, which can provide interconnected charge-transfer pathways, enable large contact area and interface channel between the electrolyte ions and the electrode material, and shorten diffusion length of lithium ions.