Microwave-anion-exchange route to spinel CuCo2S4 nanosheets as cathode materials for magnesium storage

Exploring high-performance cathode materials is of great significance for development of rechargeable magnesium batteries. Herein, two-dimensional ultrathin spinel CuCo2S4 nanosheets synthesized via microwave-assisted liquid-phase growth and anion-exchange post-sulfuration method. As a magnesium storage material, the electrochemical behavior of the CuCo2S4 nanosheets is investigated in different voltage ranges. After activated for several cycles in 0.1–2.1 V, the CuCo2S4 nanosheet material can show good electrochemical reversibility between 0.1 and 2.0 V with capacity of 191.4 mAh g−1 (50 mA g−1) and 114.5 mAh g−1 (500 mA g−1). The excellent Mg-storage properties are attributed to the fast kinetics of Mg2+ by the 2D morphology and ternary structure. A conversion reaction of the magnesium ion storage mechanism is confirmed by ex situ X-ray diffraction characterization. The excellent performance of spinel CuCo2S4 nanosheets validates the viability of the multinary strategy and sheds light on the application of 2D material design for cathode research. •Spinel CuCo2S4 nanosheets are synthesized by a microwave-anion-exchange route.•CuCo2S4 with multinary structure and 2D morphology has good rate performance.•The Mg2+ storage performance can be enhanced by altering upper cut-off voltage.•The magnesium storage mechanism of spinel CuCo2S4 is studied by ex-situ XRD.