Multiple structural defects in poor-crystalline In-doped NiCo2O4 nanoneedles synergistically and remarkably enhance supercapacitive performance

Abstract

Simultaneous acquirement of enhanced activity, improved stability, and reduced cost still is a tremendous challenge in the research of supercapacitors (SCs). In this work, we report a fascinating strategy to synthesize poor-crystalline Indium (In)-doped NiCo2O4 (In-NiCo2O4) nanoneedles with oxygen vacancies (Vo) on the carbon fiber (CF) (In-NiCo2O4/CF) by a simple laser-assisted technique. In doping not only could create more Co2+ and rich Vo but also could induce the distortion of [CoO6] in the In-NiCo2O4 lattices through the strong electronic interaction between the doped In and Co atoms, thus leads to the significant increment of active sites and pronounced enhancement of the electrical conductivity and charge transfer efficiency. Meanwhile, the high BET surface area and poor crystalline structures promote the easy penetration of electrolyte ions. Based on the synergistic effect of the above multiple structural advantages, In-NiCo2O4/CF as an advanced electrode exhibits a high supercapacitor performance with a high specific capacitance of 2375.1F g−1 at a current density of 1 A g−1, a high rate capability and 89.3% of the capacitance retention after 10,000 cycles. Moreover, a solid-state asymmetric supercapacitor successfully assembled based on In-NiCo2O4/CF and active carbon electrodes has a high energy density of 60.2 Wh kg−1 at a power density of 985.5 W kg−1 and excellent cycle stability. Density functional theory (DFT) calculations further reveal the enhanced electrochemical activity. It is believed that our assembled asymmetric supercapacitors could rich the next generation of energy-storage devices.