MoS2/Carbon Cloth As Free-Standing and Flexible Anode for Sodium-Ion Hybrid Capacitors

Abstract

Sodium-ion hybrid capacitors (NICs) combine the advantages of both battery and supercapacitor, exhibiting high energy and power density. Nevertheless, the sluggish kinetics of battery-type anodes limits its synergy effect with capacitor-type cathodes, which impedes both rate performance and cycling stability. Therefore, it is necessary to develop suitable anode materials for NICs, in order to enlarge the working voltage and long-term stability. Molybdenum disulfide (MoS­2) is a material with layer structure and can easily store lithium and sodium ions, showing promising energy storage characterization. However, the low electrical conductivity and particles aggregation problems confines its capacity performance. In this work, we grow crescent-like MoS­2 on the carbon cloth to prepare a free-standing and flexible anode without binder. MoS­2 is mainly in charge of ion intercalation and deintercalation; on the other hand, carbon cloth is utilized as a conductive substrate for MoS­2 growth. The Raman shift peaks of MoS­2 /carbon cloth are at about 375 cm-1 and 402 cm-1, corresponding to MoS­2 in-plane and out-of-plane vibration modes. Energy dispersive spectroscopy mapping shows that MoS­2 is uniformly distribute on the carbon substrate. These results demonstrate that MoS­2 successfully grew on the carbon cloth. Furthermore, electrochemical performances of MoS­2 /carbon cloth electrodes were measured in the potential range from 0.01 V to 3 V vs. Na/Na+. After combining MoS­2 with carbon cloth, the discharging capacity enhanced from 110 mA h g-1 to about 250 mA h g-1 at 50 mA g-1. These results indicate that MoS­2/carbon cloth hybrid material is a potential anode for NICs. Keywords: Na-ion hybrid capacitors, MoS­2, Free-standing and flexible anode Figure 1