Carbon coated MoS2 nanosheets vertically grown on carbon cloth as efficient anode for high-performance sodium ion hybrid capacitors

Abstract

Sodium-ion hybrid capacitors (NIHC) with sodium ion battery type anodes and supercapacitor type cathodes are emerging as an attractive energy storage device due to the integration of high energy, high power and long lifetime. However, the battery type electrodes usually exhibit sluggish reaction kinetics than capacitor type cathodes due to slow Na ion insertion and extraction, which greatly hinders the rate performance. In this paper, carbon coated MoS2 nanosheets are vertically grown on carbon cloth (CC) substrate using a hydrothermal reaction followed by calcination. The expanded interlayer distance of the MoS2 ensures high ionic mobility while the highly conductive CC not only provides a self-supporting structure without the addition of insulative binder and additional conductive additive, but also effectively prevents the restacking of the MoS2 sheets during cycling. Thus the architecture delivers a high area capacity of 0.511 mAh cm−2 at a current density of 0.2 mA cm−2 and a stable capacity retention of 83.3% after 200 cycles at 1 mA cm−2. Furthermore, NIHC constructed with above anode delivers a high areal energy density of 1.22 mWh cm−2 at a power of 0.76 mW cm−2, demonstrating an excellent energy-power delivery.