Alkali conversion of Ni-Co nanoarrays on carbon cloth for a high-capacity supercapacitor electrode

5 years ago

Alkali conversion of Ni-Co nanoarrays on carbon cloth for a high-capacity supercapacitor electrode

Three-dimensional free-standing nanoarray electrodes with hierarchical structure grown on carbon cloth substrate have attracted great interest for flexible energy storage devices. However, the direct growth of active material with a large mass loading on carbon fibers is difficult because of the hydrophobic nature. Herein, “two-step” growth route is adopted to achieve high-loading Ni-Co carbonate hydroxide nanowire arrays, in which the effect of electrochemical pre-activation is discussed. A facile and novel process is used to boost the areal capacity by converting Ni-Co carbonate hydroxide nanowires to hydroxide nanowire-supported nanoplate arrays in an alkaline solution. The areal capacity of the as-soaked free-standing Ni-Co hydroxide nanoarrays electrode increases from 856mC·cm⁻² (152C·g⁻¹) to 1944mC·cm⁻² (348C·g⁻¹) and 3028mC·cm⁻² (542C·g⁻¹) at 2mA·cm⁻² after soaking for 8h and 16h. The electrochemical pre-activation is important for achieving high mass loading as well as high rate capability. Moreover, the as-soaked electrode is employed as the positive electrode for hybrid supercapacitor. The device possesses a high areal capacitance of 1.47F·cm⁻² at 1mA·cm⁻², a large energy density of 6.7mWh·cm⁻³ at 11.6mW·cm⁻³. This work gives an insight for designing high-loading three-dimensional electrodes and paves a new way to construct binder-free film electrode for high-performance hybrid supercapacitor applications.

Publisher URL: www.sciencedirect.com/science

DOI: S0013468617315505