Cauliflower-Like Ni/MXene-Bridged Fiber-Shaped Electrode for Flexible Microsupercapacitor
Narges Darmiani, Azam Iraji zad, Ali Esfandiar, Parvin Asen
Abstract
Microscale, flexible, and lightweight electrodes are of interest for the generation of light and miniaturized energy storage systems such as microsupercapacitors. Wire or fiber-shaped electrodes can be considered as potential candidates for microsupercapacitor fabrication. Herein, a facile strategy for the preparation of high electrochemical performance fiber-shaped microsupercapacitors based on Ni(OH)2-Ni-Ti3C2 film on a copper wire (CW) electrode is presented. We employed a porous cauliflower-like Ni-Ti3C2 MXene film as the supporting scaffold to bridge a Ni(OH)2 active substance with a Cu wire current collector. This hierarchical structure supplies a high surface area, many electroactive sites, and a short ion diffusion pathway and delivers outstanding performance with superior capacitance (1725.23 Fcm–3 and 19.81 Fcm–2 at 4 mAcm2) and a rather high rate capability (929.23 Fcm–3 and 10.33 Fcm–2 at 20 mAcm–2). It should be noted that the electrochemical behavior of Ni-Ti3C2@CW is significantly better than that of directly growing Ni on Cu wire due to the cauliflower-like morphology and high conductivity of the Ti3C2. Furthermore, a fiber-shaped supercapacitor (FSC) is assembled using Ni(OH)2-Ni-Ti3C2@CW and Ti3C2@CW as the positive and negative electrodes, respectively. The fabricated FSC shows high capacitance (72.35 Fcm–3 and 756 mFcm–2 at 1.5 mAcm–2), good rate capability, a maximum energy density of 206 μWhcm–2 at a power density of 1.94 mW cm–2, long cycling stability (89.3% capacitance retention after 7000 cycles at 50 mVs–1), and good flexibility. Therefore, the introduced wire-shaped electrode through a simple process could be a promising approach for a new class of microsupercapacitors.