Abstract
Rational design of positrode material with kinetics matching with negatrode is essential to achieve favorable electrochemical performance for hybrid supercapacitor. In this paper, we prepare a series of Mn substituted NiCo2O4 (MNCO) nanowires arrays with different substitution ratios via a hydrothermal-annealing strategy. We find from first-principles calculation that Mn3+ ions preferentially substitute Ni3+ ions at the octahedral sites enables Mn3+ act as an n-type dopant and induce a higher electron density of states near the Fermi level, especially for MNCO with Mn/Ni molar ratios of 2:6. In addition, the Mn substitution can increase the energy overlap between the eg, β band of Ni and Mn and d7 configuration of tetrahedral sites Co2+ and enhance the charge transfer ability from Ni to O ions, which also plays an important role in improving electrochemical activities. The electrochemical experiment results show that the optimal MNCO electrode exhibit a large specific capacity of 200.3 mAh g−1 (1441.8 F g−1) and high rate capability (62.8%). The enhanced electrochemical activity and electrochemical reaction kinetics of positrode material is crucial for high power and energy density hybrid supercapacitors.
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