A facile enhancement in battery-type of capacitive performance of spinel NiCo2O4 nanostructure via directly tuning thermal decomposition temperature

Abstract

A facile, low cost and time-saving method to synthesize porous NiCo2O4 nanoplatelet and nanorod structures is developed via a simple two-step route. A flakes assembled precursor containing Ni-Co hydroxides is firstly prepared via a facile, low-cost chemical bath coprecipitation process only using diluted ammonia solution as a precipitant to govern over the nucleation, growth, and agglomeration processes.Then, porous NiCo2O4 nanoplatelet and nanorod structures are successfully obtained through pyrolyzing the above precursor. The influence of the calcination temperature is mainly studied on the pyrolysis reaction. The calcination temperature has statistically significant effects on the morphology and structure evolution, crystallinity, electronic conductivity and the electrochemical performances of the products. The optimized, nanoplatelet predominated NiCo2O4 spinel, calcinated at 300 ∘C for 6h (denoted as NC300), has excellent crystallinity and electric conductivity. It shows a superior-specific capacitance of 1362Fg−1 at a current density of 1Ag−1.When the current density increases to 16Ag−1, the specific capacity still retains 964Fg−1 (70.8% capacity retention). Ragone plot indicates maximum energy density of our porous NC300 electrode is 75.67Whkg−1 at a power density of 499.82Wkg−1. Cycle-life tests show that the specific capacitance of NC300 is nearly stable between 300 and 1500 cycles, indicating its potential use in energy-storage field.The simplicity and practicability of the modified pyrolysis process may facilitate the successful commercial applications in electrochemical capacitors for nanostructured NiCo2O4 spinel.