High-performance heterojunction Ti3C2/CoSe2 with both intercalation and conversion storage mechanisms for magnesium batteries

Searching for high-performance cathode materials has become the key to the development of rechargeable magnesium batteries (RMBs). Herein, we successfully constructed a novel heterostructure Ti3C2/CoSe2 by in-situ selenization of Ti3C2/ZIF-67 composite as a cathode for RMBs. In the heterostructure, the unique MXene structure plays a role in maintain the stability of the material skeleton during the charge/discharge process, and the CoSe2 nanoparticles can fully deliver the advantage of high capacity. As a result, the Ti3C2/CoSe2 heterojunction has great obvious improvement in electrochemical performance, leading to a high-rate performance (75.7 mA h g−1 at 1000 m A g−1) and long cycling life with ~79% capacity retention after 500 cycles. Moreover, the Mg storage mechanism and Mg-migration kinetics of Ti3C2/CoSe2 are analyzed and discussed by ex-situ X-ray diffraction and X-ray photoelectron spectroscopy. In particular, the Ti3C2/CoSe2 heterostructures display impressive Mg storage performance (67.3 mA h g−1 after 70 cycles at 55 °C) in quasi-solid-state magnesium batteries. Importantly, the selenization strategy has inspired the exploration of the preparation of other novel MXene-based selenide electrodes for high-performance energy storage devices.