Template-directed synthesis of Co2P/MoSe2 in a N-doped carbon hollow structure for efficient and stable sodium/potassium ion storage

Multi-component hollow structures with attractive physicochemical properties, often show superior electrochemical performance in alkali-ion batteries. Herein, a template-directed strategy is proposed for synthesis of multi-component hollow nanosphere with Co2P/MoSe2 confined in N-doped carbon (Co2P/MoSe2@NC). This structure markedly improves the kinetics, provides sufficient active sites and accommodates volume expansion, for the large-sized K+/Na+ storage, which is proved by the in-situ and ex-situ transmission electron microscopy measurements. As for sodium storage, a capacity of 230 mAh g−1 over 1500 cycles can be retained at current of 2.0 A g−1, with a capacity retention of 83%. In terms of K+ storage, Co2P/MoSe2@NC anodes display excellent rate capability and ultra-long cycling performance (177.6 mAh g−1 at 1.0 A g−1 for 5000 cycles with a capacity retention of 75%). Based on the analysis of electrode process by comparison of dQ/dV curves and theoretical calculations, the intercalation-conversion reaction for K+ storage is more reversible and the weaker adsorption of K+ on the Co2P/MoSe2 interface can guarantee the stable storage of the K+-ions. High energy density of 43.34 Wh kg−1 at power densities of 22263.7 W kg−1 is delivered in the Co2P/MoSe2@NC//AC potassium-ion hybrid supercapacitor. This indicates that a selenide/phosphide combination can exert useful synergistic effects on the large-sized K+/Na+ storage, and is a promising anode candidate.