Flexible MoSe2/MXene films for Li/Na-ion hybrid capacitors

MoSe 2 presents a prospect in sodium-ion capacitors (SICs) and lithium-ion capacitors (LICs), which are considered as promising new energy systems because they possess the merits of both batteries and supercapacitors . In this work, we develop a flexible and free-standing MoSe 2 /MXene film with sandwich structure as an anode for SICs and LICs. The highly conductive MXene sheets can boost the electrochemical activity of MoSe 2 nanoparticles . Meanwhile, the MoSe 2 nanoparticles can also enlarge the interlayer spacing of MXene film, facilitating the permeation of electrolyte and eventually leading to fast reaction kinetics of MoSe 2 . The sandwich structure can effectively limit the loss of intermediate products generated during the insertion/extraction reactions of MoSe 2 , giving rise to a durable cycle performance. The MoSe 2 /MXene film with an optimized mass ratio exhibits much improved Li/Na storage performances as compared with the pristine MoSe 2 , particular the long term cyclic stability. SICs and LICs could deliver high energy/power densities (Max 110.1 Wh kg −1 /4764.7 W kg −1 and 84.9 Wh kg −1 /3288.3 W kg −1 , respectively), as well as long lifespans, demonstrating the prospective of such MXene/MoSe 2 film electrode towards alkali metal ion capacitors. Assembled flexible SICs/LICs prototypes further prove the potential application for the future flexible energy storage devices. MoSe 2 /MXene film electrode with a sandwich structure exhibits a great electrochemical performance for SICs and LICs. • Flexible and free-standing MoSe 2 /MXene films with sandwich structure are prepared. • The cyclic performance of MoSe 2 is much improved by this composite film way. • The probed mechanism gives insights into the ion storage performance. • MoSe 2 /MXene film exhibits a great performance as the anode for SICs and LICs.