Frogspawn-Like P-Rich Copper Phosphides@N-doped Carbon As Advanced Potassium-Ion Batteries Anodes

Metal phosphides (MPs) are drawing increased attention as potential anode materials for high-performance potassium-ion batteries (PIBs) because of their high theoretical capacity and relatively low working potential. However, MPs usually suffer from structural degradation resulting from the large volume changes in the course of cycling. Herein, we design a frogspawn-like phosphorus (P)-rich copper phosphides@N-doped carbon (CuP2@C) and synthesize it through a low-temperature rapid phosphorization route. With this unique architecture, the composite material possesses enhanced conductivity and voids to alleviate the volume variations upon the potassiation. Moreover, this proposed phosphorization method can rapidly obtain P-rich copper phosphides to retain the structure of precursors as much as possible. The resultant CuP2@C hybrid then delivers a high depotassiation capacity (463 mAh g–1 at 0.05 A g–1), good rate performance (206 mAh g–1 at 2 A g–1), and outstanding cycle capability (a tiny attenuation rate of 0.08% per cycle during 1000 cycles at 2 A g–1). Furthermore, the assembled full PIBs from using a well-developed potassium Prussian blue cathode exhibit impressive performance (78.8 mAh g–1 at 0.1 A g–1). The frogspawn-like architecture and proposed fast phosphorization strategy can be applied to synthesize other P-rich MPs for energy storage systems.