2D/2D heterojunction of cobalt iron selenide and nickel cobalt phosphate for boosted supercapacitor performance

Abstract

The performance of hybrid supercapacitors is restricted by inferior matched electrochemical kinetics of cathode and anode materials, leading to unsatisfactory energy density and poor cyclic stability. Herein, hierarchically porous cobalt iron selenide (Co0.7Fe0.3Se2) @ nickel cobalt phosphate (NiCoPO) nanosheet arrays are successfully fabricated on carbon cloth substrate via an electrodeposition method, a hydrothermal treatment, followed by an electrodeposition process. The well-designed Co0.7Fe0.3Se2 @NiCoPO cathode material not only combines the merits of high electrical conductivity of Co0.7Fe0.3Se2 and high electrochemical activity of NiCoPO, but also generates interaction and synergistic effect between two constituents. Profiting from its unique core-shell heterostructure with short ion transfer roadways and enhanced conductivity, Co0.7Fe0.3Se2 @NiCoPO electrode yields a specific capacity of 887.4 C g−1 at 1 A g−1, splendid rate capability of 86.2% capacity retention at 20 A g−1, along with a wonderful cycling stability of 91.1% over 5000 cycles. Besides, a Co0.7Fe0.3Se2 @NiCoPO//porous carbon hybrid supercapacitor achieves a maximum energy density of 68.0 Wh kg−1 at 826.6 W kg−1 and outstanding long-term cycling performance with 95.7% initial capacity over 10,000 cycles. Our results propose an efficient approach to construct selenide/phosphate heterojunction with special morphology and nanostructure for advanced energy storage devices.