High magnetic field-engineered high mass loading sulfides with well-ordered hierarchical nanostructures for all-solid-state supercapacitors

Low energy density is becoming the largest sore point of supercapacitors. Constructing all-solid-state asymmetric supercapacitors (AASCs) with high mass loading and high utilization of electrochemically active materials can largely remedy the drawback. Herein, well-ordered hierarchical porous NiCo2S4 pine needles on carbon cloth (CC) with a loading mass as high as 10.76 mg cm-2 (NCS-12 T) were fabricated by low-temperature topotactic vulcanization of the high-mass-loading (Ni, Co)(CO3)0.5(OH)center dot 0 center dot.11H2O precursor (NCCH-12 T) yielded under 12 T high magnetic field (HMF). The loading mass on each CC tends towards equivalence and increases remarkably with the rise of HMF by guaranteeing sufficient ion supply. Impressively, a high overall capacitance of 10.46F cm-2 at 5 mA cm-2 was achieved without sacrificing the specific capacitance and rate capability that are slightly superior to those of the low mass loading NiCo2S4 electrodes instead. The striking electrochemical performances are ascribed to the available ion and electron transport in the whole electrode, which results from the construction of three-dimensional hierarchical porous nanostructures and HMF-derived well-ordered and uniform deposition via boosting ion transport. Finally, the NCS-12 T-based AASCs with high mass loading exhibit a high energy density of 280 mu Wh cm-2 at the power density of 1.71 mW cm-2, exceeding most state-of-the-art supercapacitors.