Construction of porous NiCo2S4 hierarchical nanoflakes based on zeolitic imidazolate frameworks as battery-type electrodes for high performance supercapacitors

Abstract

Electrode materials with hierarchical nanoflakes structure show an important application potential in the efficient storage of electrochemical energy. In this work, a bimetallic sulfide NiCo2S4 with a novel controllable structure by adopting a layered double hydroxide (LDH) based on zeolitic imidazolate frameworks (ZIFs) template-oriented strategy is designed. The as-synthesized NiCo2S4 exhibits a hierarchical layered structure composed of nanoparticles with large specific surface area. This unique nanostructure provides abundant electrolyte-accessing sites and sufficient contact between the electroactive materials and electrolytes. As a result, the porous NiCo2S4 electrode exhibits a high specific capacity of 968 C g−1 at 1 A g−1 and an extraordinary rate capability of 91% at the current density of 10 A g−1. Furthermore, a hybrid supercapacitor is assembled with NiCo2S4 as the positive electrode and activated carbon as the negative electrode. The as-prepared device can deliver a high specific energy of 45.1 Wh/Kg at a high specific power of 699.7 W/Kg and its long-term cycling stability can reach 74.7% after 20000 cycles.