Self-assembled superstructure of carbon-wrapped, single-crystalline Cu3P porous nanosheets: One-step synthesis and enhanced Li-ion battery anode performance

Robust superstructures of self-assembling nanoscale building blocks are of functional and practical interest for improving the performance of materials in various advanced technological applications. Herein, we successfully synthesize a self-assembled, three-dimensional (3D) superstructure of carbon-wrapped, single-crystalline Cu3P porous nanosheets by one-step heat treatment of Cu foam with a phosphorus-containing resin. In this 3D superstructure, continuous single-crystalline Cu3P sheets are wrapped by uniform 5 nm-thick carbon shells (<30 nm thick) and have a length/thickness ratio of up to 3000. The unique arrangement of the carbon shell offers both close Cu3P to carbon contact aiding electron transport, in addition to void space required for buffering volume change of Li-ion insertion and extraction in Cu3P as a Li-ion battery anode. Furthermore, the abundant and hierarchical distribution of pores in the Cu3P provides tunnels for fast electron and Li-ion transport and an increased number of Li-ion adsorption/desorption sites. Accordingly, the unique structure has high specific capacity, highly improved rate capacity, as well as excellent cycling stability.