Three-dimensional, hetero-structured, Cu3P@C nanosheets with excellent cycling stability as Na-ion battery anode material

Abstract

Transition metal phosphides, especially copper phosphide nanocrystals, afford promising anode material candidates for sodium ion batteries. However, despite their high specific capacity, their performance is generally thwarted by rapid capacity fading due to limited cycling stability. To address this issue, we report a three-dimensional nanoarchitecture comprising a heterostructured assembly of Cu₃P@C nanosheets synthesized via a simple combined epitaxial phosphidation growth/carbon deposition process. In each individual nanosheet, the thin carbon shell serves as an electron conductor and accommodates volume change of the Cu₃P single-crystalline nanosheet. On a macroscopic level, the assembled 3D nanoarchitecture offers fast ion transfer pathways and prevents aggregation of the nanosheets. As a result, the 3D Cu₃P@C nanoarchitecture delivers an exceptionally high capacity retention of 286 mA h g⁻¹ after 300 cycles at 0.1 A g⁻¹ and 156 mA h g⁻¹ after 1000 cycles at 1 A g⁻¹. This work, therefore, shows that achieving a synergistic multidimensional structure is possible via a simple one-pot method, and opens avenues to explore other metal phosphides in the same heterostructured format.