Engineering MoS2 Nanosheets on Spindle‐Like α‐Fe2O3 as High‐Performance Core–Shell Pseudocapacitive Anodes for Fiber‐Shaped Aqueous Lithium‐Ion Capacitors

Abstract

AbstractFiber‐shaped aqueous lithium‐ion capacitors (FALICs) featured with high energy and power densities together with outstanding safety characteristics are emerging as promising electrochemical energy‐storage devices for future portable and wearable electronics. However, the lack of high‐capacitance fibrous anodes is a major bottleneck to achieve high performance FALICs. Here, hierarchical MoS2@α‐Fe2O3 core–shell heterostructures consisting of spindle‐shaped α‐Fe2O3 cores and MoS2 nanosheet shells on a carbon nanotube fiber (CNTF) are successfully fabricated. Originating from the unique core/shell architecture and prominent synergetic effects for multi‐components, the resulting MoS2@α‐Fe2O3/CNTF anode delivers a remarkable specific capacitance of 2077.5 mF cm−2 (554.0 F cm−3) at 2 mA cm−2, substantially outperforming most of the previously reported fibrous anode materials. Further density functional theory calculations reveal that the MoS2@α‐Fe2O3 nano‐heterostructure possesses better electrical conductivity and stronger adsorption energy of Li+ than those of the individual MoS2 and α‐Fe2O3. By paring with the self‐standing LiCoO2/CNTF battery‐type cathode, a prototype quasi‐solid‐state FALIC with a maximum operating voltage of 2.0 V is constructed, achieving impressive specific capacitance (253.1 mF cm−2) and admirable energy density (39.6 mWh cm−3). Additionally, the newly developed FALICs can be woven into the flexible textile to power wearable electronics. This work presents a novel effective strategy to design high‐performance anode materials for next‐generation wearable ALICs.