Simultaneous phosphorization and sulfuration to Synergistically promote the supercapacitor performance of heterogeneous (CoxNi1-x)2P/CoxNi1-xS hydrangea-like microspheres

Abstract

How to effectively improve supercapacitors performances through electrode materials design is still an urgent task. Herein, a facile precursor strategy combining solvothermal synthesis and upstream gas method is proposed to regulate the structure and composition of the supercapacitor electrode material through doping and compositing. The precursors, CoxNi1-x microspheres, are synthesized through a facile solvothermal reaction with nickel/cobalt acetate in methanol without addition of any surfactants or templates, achieving the integration of cobalt and nickel species into a single structure. A subsequent simultaneous phosphorization and sulfuration process through an upstream gas method makes the CoxNi1-x precursor microspheres transform to heterogeneous (CoxNi1-x)2P/CoxNi1-xS microspheres in one step. The resulted (CoxNi1-x)2P/CoxNi1-xS microspheres show great enhanced supercapacitor performances with a high specific capacitance (1561 F g−1 at 1 A g−1 current density) and excellent cycling stability (a 89.7% capacitance retention after 5000 cycles at 10 A g−1) due to synergistic effects resulted from the coexistence of multiple elements, as well as the unique interface and structure caused by in-situ two-phase compositing, which can accelerate charge transfer and increase available active sites. Our study proves that simultaneous phosphorization and sulfuration is an effective means to adjust the microstructure of the electrode materials and thus promote their electrochemical performances.