Nickel selenide nanorod arrays as an electrode material for lithium-ion batteries and supercapacitors

The growing need for renewable energy and environmental concern has prompted extensive study into energy storage devices, especially batteries and supercapacitors and their electrode materials. Nano array structures are among the most promising electrode structures for improving the electrochemical performance of energy storage devices. In this work, nanorod arrays of nickel selenide grown on nickel foam were synthesized via a simple onestep binder-free hydrothermal method. The change in morphology and electrochemical performance were studied due to altering reaction time. The nanorod growth mechanism and its electrochemical behavior were investigated. The optimum reaction time was 18 h giving nanorod arrays of NixSey with unique electrochemical performance when inspected as an active electrode material for both lithium-ion battery (LIB) and a supercapacitor (SC). For LIB, the as-prepared electrode gave an initial discharge capacity of 632.8 mAh g(-1) with a good rate capability and coulombic efficiency. Meanwhile, as an SC electrode, it delivered a capacity of 426.5 C g(-1) at 1 A g(-1) in a three-electrode apparatus. The hybrid supercapacitor demonstrates 24.67 Wh kg(-1) specific energy at 1020.83 W kg(-1) specific power with remarkable cycle stability of 92.3 % after 9000 cycles. These results prove that nanorod arrays of NixSey are a promising electrode material for energy-storage applications.