Investigating the large potential window of NiCo2O4 supercapacitors in neutral aqueous electrolyte

Abstract

The enhancement of potential window can be identified as one of the effective pathways to boost the energy density of supercapacitors to break the limitation of practical applications. NiCo2O4 nanosheet networks grown on carbon cloth are prepared via a facile cathodic electrodeposition process with a post-annealing procedure. A neutral electrolyte of mixing 2 M LiSO4 and 0.1 M CoSO4 is employed to enlarge the potential window of the as-prepared NiCo2O4/CC electrode to 0–1.2 V (vs SCE), while the corresponding potential window in alkaline electrolyte is merely 0–0.5 V. Moreover, the NiCo2O4/CC electrode shows an excellent cycling stability of maintaining 129.7% after 10,000 cycles in neutral electrolyte. The quantitative CV kinetic analysis is carried out to explore the charge storage mechanism, manifesting that capacitive contribution is estimated as high as 64.7–81.8% at the sweep rate of 3–10 mV s−1. Results demonstrate that this neutral electrolyte can greatly boost the electrochemical characteristics of the NiCo2O4 electrode and also provide the possibility of achieving better characteristics in the field of energy storage when applied in other battery-type materials.