Enhanced faradic activity by construction of p-n junction within reduced graphene oxide@cobalt nickel sulfide@nickle cobalt layered double hydroxide composite electrode for charge storage in hybrid supercapacitor

Abstract The intrinsic faradic reactivity is the uppermost factor determining the charge storage capability of battery material, the construction of p-n junction composing of different faradic components is a rational tactics to enhance the faradic activity. Herein, a reduced graphene oxide@cobalt nickle sulfide@nickle cobalt layered double hydroxide composite (rGO@CoNi2S4@NiCo LDH) with p-n junction structure is designed by deposition of n-type nickle cobalt layered double hydroxide (NiCo LDH) around p-type reduced graphene oxide@cobalt nickle sulfide (rGO@CoNi2S4), the charge redistribution across the p-n junction enables enhanced faradic activities of both components and further the overall charge storage capacity of the resultant rGO@CoNi2S4@NiCo LDH battery electrode. As expected, the rGO@CoNi2S4@NiCo LDH electrode can deliver high specific capacity (Cs, 1310 ± 26 C g-1 at 1 A g-1) and good cycleability (77 % Cs maintaining ratio undergoes 5000 charge-discharge cycles). Furthermore, the hybrid supercapacitor (HSC) based on the rGO@CoNi2S4@NiCo LDH p-n junction battery electrode exports high energy density (Ecell, 57.4 Wh kg-1 at 323 W kg-1) and good durability, showing the prospect of faradic p-n junction composite in battery typed energy storage.