Electrochemical rapid reconstruction of 1D ZIF-L derived hollow hierarchical multiphase NiCo-S for high-performance hybrid supercapacitors

The combination of low electronegative sulfur and common transition metals has obvious advantages in easing volume expansion and improving electrical conductivity for energy storage. Herein, we developed an electrochemically assisted strategy to rapidly reconstruct ZIFs (Zeolitic Imidazolate Frameworks) with Lewis acid to obtain reticulated cross-linked hierarchical electrode NiCo-LDH@CNFs (carbon-nitrogen frameworks) with excellent active specific surface area. Simple vulcanization can effectively optimize the active site and crystal structure, and further improve the conductivity of the multi-phase electrode NiCo-S@CNFs (NiCo2S4, CoS2). Furthermore, the synergistic effect of multi-phase metal sulfides and the reasonable structure can effectually enhance the redox activity, adsorption capacity of OH-, and reduce the volume expansion and of the electrode. The results demonstrate that the specific capacity of the electrode is 433.3 mAh g-1 (6 M KOH). The prepared HSC device (hybrid supercapacitor, NiCo-S@CNFs//AC (activated carbon)) exhibits a maximum energy density of 87.2 Wh kg-1 (800 W kg-1). After 12,000 charge/discharge cycles, the capacity retention rate is still 105.1%, which has excellent cycling stability among ZIF-derived binary metal sulfides. Furthermore, parallel-connected LEDs can be lit by two series-connected HSCs, showing their practicality and great potential.