Facile constucture of amorphous/crystalline NiCoB@NiCo2S4 heterogeneous interface nanocomposites for enhanced supercapacitor performance

Abstract

Transition metal borides have shown great promise as a supercapacitor electrode material. However, the amorphous structure of metal borides leads to the structural collapse of electrode material during electrochemical cycling, which seriously affects the stability of the material. In the present work, we successfully construct amorphous/crystalline NiCoB@NiCo2S4 heterogeneous interfacial composites by introducing the outer layer of sulfide to improve the electrochemical performance. NiCoB@NiCo2S4 shows a specific capacitance of 1562 F g−1 at a current density of 1 A g−1 and still possesses 58% specific capacitance even at a higher current density of 50 A g−1. The asymmetric supercapacitor (ASC) device assembled with Bi2O3@C as the negative electrode and NiCoB@NiCo2S4 as the positive exhibits a high energy density of 98.75 Wh kg−1 at a power density of 750 W kg−1. The ASC also exhibits excellent cycling stability with capacitance retention of 118% after 10000 cycles at a current density of 10 A g−1, which fully demonstrates the practical applications value of NiCoB@NiCo2S4//Bi2O3@C.