Morphology tuned synthesis of battery-type NiCo2O4 for high performance hybrid supercapacitors

Abstract

NiCo2O4, as a typical battery material, has been researched in LIB and hybrid supercapacitors. The electrochemical performance of NiCo2O4 is greatly influenced by its morphology. Interestingly, alkaline substances play a vital role in the morphology formation of NiCo2O4. Therefore, it's necessary to study the effect of alkaline substances on the morphology of NiCo2O4. In this work, nanosheet-like, ball-like and urchin-like NiCo2O4 are formed by sodium hydroxide, ammonium hydroxide and urea. Nanosheet-like NiCo2O4 formed by sodium hydroxide exhibits the most outstanding electrochemical performance. Northworthy, huge morphological changes emerge while tailoring the concentration of sodium hydroxide. Nanorod-like NiCo2O4 appears at the sodium hydroxide concentration of 0.025 M. It also displays high capacity of 866 C g−1 at 1 A g−1 and superior cycle stability with 95% capacitance retention after 10000 cycles. In the practical application, coin-type hybrid supercapacitors deliver maximum energy density of 57.78 Wh kg−1 and power density of 8000 W kg−1.