960化工网
Electrodeposition of honeycomb-shaped NiCo2O4 on carbon cloth as binder-free electrode for asymmetric electrochemical capacitor with high energy density
Yufeng An,Zhongai Hu,Bingshu Guo,Ning An,Yadi Zhang,Zhimin Li,Yuying Yang,Hongying Wu
RSC Advances Pub Date : 04/04/2016 00:00:00 , DOI:10.1039/C6RA04788B
Abstract

Combining high-capacitive metal oxides and excellent conductive carbon substrates is a very significant strategy to achieve high-performance electrodes for electrochemical capacitors (ECs). Herein, the bimetallic (Ni, Co) hydroxide is uniformly grown on the electro-etched carbon cloth (CC) by a facile co-electrodeposition method, and then the honeycomb-shaped NiCo2O4/CC (HSNC) composite is formed by transforming the hydroxide precursor into its bimetallic oxides through the subsequent thermal treatment. The special structure of the HSNC as binder-free electrode is responsible for its excellent electrochemical performance with carbon-like power feature. The experimental results show that HSNC electrode exhibits a high specific capacitance with remarkable cycle stability (94.3% after 10 000 cycles at 10 A g−1) in the three-electrode configuration. To evaluate further the capacitive performance of the as-prepared binder-free electrode in a full cell set-up, an asymmetric electrochemical capacitor (AEC) is assembled by using the HSNC as the positive electrode and reduced graphene oxide/carbon cloth (rGO/CC) as the negative electrode in KOH electrolyte. The as-assembled device presents an energy density as high as 32.4 W h kg−1 along with power density of 0.75 kW kg−1, comparing with nickel-metal hyoride battery (Ni-MH) batteries (30.0 W h kg−1 at 0.35 kW kg−1). Even at the power density of 37.7 kW kg−1 (50-time increase, a full charge–discharge within 3.5 s), energy density still holds at 17.8 W h kg−1, indicating an outstanding rate capability. Furthermore, the as-fabricated device exhibits a long cycle lifetime (76.5% after 10 000 cycles at 3 A g−1) with a cell voltage of 1.5 V.

Graphical abstract: Electrodeposition of honeycomb-shaped NiCo2O4 on carbon cloth as binder-free electrode for asymmetric electrochemical capacitor with high energy density
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