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High-Performance, Flexible, All-Solid-State Wire-Shaped Asymmetric Micro-Supercapacitors Based on Three Dimensional CoNi2S4 Nanosheets Decorated–Nanoporous Ni–Zn–P Film/Cu Wire

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journal contribution
posted on 22.08.2019, 14:09 by Saeed Shahrokhian, Leila Naderi
Demand increasing for next generation portable and miniaturized electronics has aroused much interest to explore microscale and lightweight energy storage devices. Herein, we demonstrate successful development of flexible wire-shaped micro-supercapacitors (micro-SCs) based on novel CoNi2S4/E-NZP film@Cu wire electrode. The etched Ni–Zn–P (E-NZP) film was synthesized by directly deposition of NZP film on Cu wire, followed by a chemical etching process. Alkaline etching treatment provides a micro- and mesoporous structure with high surface area and facilitates the penetration of electrolyte ions into the electrode matrix. Then, CoNi2S4 nanosheets as electroactive material are electrochemically grown onto the E-NZP film@CW electrode under a constant potential. The synergistic effects contributed by various components inside the CoNi2S4/E-NZP@CW electrode deliver superior performances with a high specific capacitance of 1.12 F cm–1, 8.9 F cm–2, and 889.68 F cm–3 at 4 mA cm–2, outstanding rate capability (0.66 F cm–1, 5.3 F cm–2, and 529.02 F cm–3 at 80 mA cm–2) and long-term cycling stability (93.4% capacitance retention after 7000 cycles). Moreover, a flexible solid-state asymmetric micro-SC is fabricated using CoNi2S4/E-NZP film @CW as the positive electrode and rGO-coated carbon fiber (rGO/CF) as the negative electrode. The fabricated device exhibits high length, areal and volumetric capacitances of CL: 40 mF cm–1, CA: 0.241 F cm–2 and CV: 18.54 F cm–3, good mechanical stability with a maximum energy (EL, 18 μW h cm–1; EA, 108.4 μW h cm–2; and EV, 8.34 mW h cm–3), and power densities (PL, 1454 μW cm–1; PA, 9280 μW cm–2; and PV, 716.9 mW cm–3). This work provides a new and facile approach to develop high-performance wire-shaped electrodes as a new generation in energy storage applications.