A Rechargeable Quasi-symmetrical MoS2 Battery

Summary

The symmetrical configuration is attractive for electrochemical energy storage devices due to using one electrode material, but it is difficult to achieve for a rechargeable battery. Here, we propose an electrochemical activity modulation method to construct a quasi-symmetrical rechargeable battery with decoupled conversion reactions of the anionic/cationic counterparts of covalent transition metal sulfides. The modulated process contains potential window and electrolyte modulation, followed by a predesigned conversion reaction. For molybdenum disulfide (MoS₂), after cathodic modulation the sulfur redox (S⁰ to S²⁻) inside MoS₂ was activated as redox center of cathode, resulting in a capacity increase of one order of magnitude and high cycling stability. Meanwhile, an anodic-modulated MoS₂ anode displayed high capacity due to the reversible conversion between Mo^x+ and Mo⁰. Coupling this cathode and anode, a quasi-symmetrical battery is fabricated and opens up a new direction for building high-energy electrochemical systems.