Reversible Mg insertion into chevrel phase Mo6S8 cathode: Preparation, electrochemistry and X-ray photoelectron spectroscopy study

Highlights: • Surface modification of Mo6S8 to enhance the reactivity against Mg. • Mechanism study using XPS and EIS. • Excellent Mg-ion battery performance. - Abstract: Electrical energy storage is absolute for complete usage of all renewable energy sources. Herein, we have studied the electrochemical performance of Chevrel phase Mo₆S₈ as cathode material towards rechargeable Mg battery. Solution chemistry route is adopted for the synthesis of Mo₆S_8. The morphology, phase purity is analyzed by Scanning Electron Microscopy, Transmission Electron Microscopy, and X-Ray Diffraction techniques. The cyclic Voltammetry and Galvanostatic charge-discharge studies confirmed the reversibility of Mg-ion insertion. Herein, Mo₆S₈ cubes show excellent capacity retention of 70 mAh g⁻¹ for 200 cycles at C/5 rate. The role of CNT in improving rate performance was also demonstrated. The reasonable reversible capacity, rate performance, and cycling stability reveal the feasibility of Mo₆S₈ material for future rechargeable Mg battery. In order to study the kinetics of Chevrel phase compound upon cycling, EIS study was carried out. The redox process upon insertion/extraction is investigated by X-ray Photoelectron spectroscopy which shows no change in oxidation state of a transition metal.