Mesoporous carbon rods capable of fast transport of axial electrons and radial ions for ultra-thick supercapacitor electrodes

Abstract

Increasing the energy density (Ewt) under large currents is always highly desired for supercapacitors using thick carbon electrodes. Herein, we report an ultra-thick carbon electrode composed of mesoporous carbon rods (MCR) with ultrahigh specific surface area. At 250 μm, it exhibits the highest capacitance (Cwt, 239 F g −1 at 1 A g −1) and Cwt retention (53% at 100 A g −1) in EMIMBF4 as far as we know, and ultrahigh Ewt (132 Wh kg−1) and achievable power density (Pwt, 74 kW kg−1). Even at ultra-thick 600 μm, its Ewt and Pwt are still up to 95 Wh kg−1 and 70 kW kg−1, respectively, with the decay of Cwt at 50 A g −1 < 3% (much smaller than commercial carbon YP-50F). Such excellent performance is attributed to the unique MCR structure, i.e., the micron-sized rod-like frame structure consisted of interconnected carbon nanocages acting as axial electron channel, as well as the stacking pores formed by MCR serving as radial channels for ions, finally enabling electrons and ions to be rapidly transferred in the axial and radial directions, respectively. It fully demonstrates its potential application prospects in scenarios requiring high energy and high power at the same time.