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

Highlights: • NiCo₂O₄ nanosheet networks were prepared on carbon cloth. • The electrochemical behaviors were exploded in different electrolyte. • The potential window was enlarged to 0–1.2 V (vs SCE) in neutral electrolyte. • The NiCo₂O₄/CC electrode shows an excellent cycling stability. • The charge storage mechanism is confirmed via the kinetic analysis. -- 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.