Search

Summary: Potassium ion batteries (KIBs) have attracted considerable attention as a next‐generation large‐scale energy storage system. Due to the large diameter of K+ ions, developing advanced electrode materials to achieve high‐performance KIBs is challenging. In this paper, one‐dimensional (1D) hybrid nanostructures comprising a MoSe2 core and a CoSe2/N‐doped carbon shell (denoted as MC‐Se@NC) are successfully synthesized by thermal treatment of Co‐based metal‐organic framework (ZIF‐67)‐coated MoO3 nanorods. The unique 1D morphology and synergistic effect between the different elements provide sufficient electrochemical reaction sites and facilitate the reaction kinetics. Further, the N‐doped carbon coating alleviates the volume fluctuation and pulverization of the active materials during cycling and improves the electrode conductivity. Accordingly, when applied to KIBs, the MC‐Se@NC anode delivers a high reversible capacity of 327 mA h g−1 at 0.5 A g−1 after 150 cycles, and remarkable rate capability of 190 mA h g−1 at 2.0 A g−1. Furthermore, to explore the practical application of MC‐Se@NC anode, a K‐ion full cell consisting of MC‐Se@NC anode and Prussian blue cathode is fabricated and characterized. As a demonstration, a light‐emitting diode (LED) is successfully powered by the K‐ion full cell. These excellent electrochemical properties of MC‐Se@NC present possibilities for the commercialization of KIB‐based large‐scale energy storage systems. [ABSTRACT FROM AUTHOR]

Summary: Sodium‐ion batteries (SIBs) and potassium‐ion batteries (KIBs) have received much attention as next‐generation energy storage systems owing to the abundance. Nevertheless, they face great challenges in the design of optimum electrode materials for practical applications. Herein, we prepared a unique two‐dimensional structured composite consisting of N‐doped carbon‐coated CoSe2 nanocrystals and MXene nanosheets (CoSe2@NC/MX) for efficient electrochemical Na‐ and K‐ion storage. In this strategy, a Co‐based zeolitic imidazole framework (ZIF‐67) was deposited on the surface of MXene nanosheets, and the subsequent selenization process resulted in the transformation of the ZIF‐67 into CoSe2@NCs. The unique structure can shorten the transport pathways for electrons/ions and provide sufficient space to accommodate the volume change of the active materials. Furthermore, the N‐doped carbon matrix and MXene can enhance the robustness of the electrode materials. Accordingly, the composites exhibited enhanced electrochemical performance in terms of cycle stability (317 mA h g−1 after 200 cycles at 0.5 A g−1) and rate capability (343 mA h g−1 at 7.0 A g−1) for SIBs. For KIBs, they exhibited a high reversible capacity of 358 mA h g−1 at 0.5 A g−1 after 100 cycles and 276 mA h g−1 at a high rate of 2.0 A g−1. [ABSTRACT FROM AUTHOR]