Binder free 3D highly ordered Ta-NiCo2O4@CC nano-needle arrays as an efficient flexible supercapacitor electrode

Free standing metal oxide based electrodes having well-ordered nanostructures growth are significant for high performance flexible supercapacitor electrode applications. Along with the aligned nanostructures, the doping based material defects can lead to crystal imperfections and morphology engineering which can have the ability to enhance their specific performance. Here, facile hydrothermal approach has been employed to synthesize the binder free Ta-doped NiCo2O4 nano-needle arrays on carbon cloth (CC) substrate which serves as the backbone for the current collector in flexible portable gadgets. The synthesized nano-needles have the ability to enhance the specific surface area and exhibiting a greater number of active sites. The addition of tantalum (Ta) dopant modifies NiCo2O4 electronic structure by creating defects and reducing crystallite size from 26 nm to 15 nm resulting in improved electron transportation conductivity. The NC-5@CC nano-needles possess large internal surface charge leads to rapid redox reactions compared to pristine NiCo2O4 (NC-0@CC) micro-rods. The NC5@CC electrode exhibited the high specific capacitance (Cs) of 3007.4 Fg-1 at 1 Ag-1 . Additionally, this electrode showed remarkable cycling stability retaining 95.1 % after completing 10,000 cycles of GCD at 1 Ag-1 . The smallest value of Rs = 1.32 Omega and R ct = 3.07 Omega for NC-5@CC shows superior electron transportation properties leads to high electrochemical performance. The increase in pseudocapacitive trend is also verified from EIS fitting. The power law (b = 0.7) and Dunn method of capacitive-diffusive shows these binder free well-aligned nano-needles arrays have the ability to utilize in high performance flexible pseudocapacitors at industrial level.