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

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.