Purified molybdenite encapsulated in N-doped carbon nanofibers as binder-free anodes for flexible lithium-ion hybrid capacitors

Abstract

Molybdenite possesses high natural abundance and a high theoretical lithium storage capacity but is limited by its low intrinsic conductivity and volume expansion during cycling. Herein, a flexible and binder-free anode is designed by encapsulating purified molybdenite nanosheets within nitrogen-doped carbon nanofibers (MoS₂@CNF) via a scalable electrospinning and carbonization process. The unique “necklace-like” structure, in which MoS₂ nanosheets are uniformly embedded within interconnected conductive CNFs, not only exposes abundant active sites but also enhances both the electrical conductivity and mechanical stability. The delicate nanostructure of MoS₂@CNF facilitates rapid ion/electron transport and alleviates the volume stress of MoS₂ during electrochemical processes, consequently contributing to its outstanding rate capability (544.0 mAh g⁻¹ at 2 A g⁻¹) and excellent cycling performance (716.9 mAh g⁻¹ after 500 cycles at 1 A g⁻¹). The MoS₂@CNF anode is further coupled with a flexible cathode (activated carbon cast onto CNF) to construct a lithium-ion hybrid capacitor, which exhibits a high energy and power density (84.3 Wh kg⁻¹ at 10 kW kg⁻¹) while demonstrating negligible capacity decay even under harsh bending conditions. This work provides a cost-effective strategy for transforming natural ore into high-performance electrodes for flexible energy storage.