Layered MoSi2N4 as Electrode Material of Zn–Air Battery

Abstract

Metal–air batteries have an outstanding advantage of combining high‐energy‐density metal anodes with active air cathodes. The advanced properties of layered materials can be utilized to improve the internal reaction rate and charge storage of metal–air batteries. Layered MoSi2N4 is a newly synthesized MAX phase (where M is transition metal, A is Al or Si, and X is C, N, or both). This work investigates the possibility of MoSi2N4, a layered MAX phase, as both the cathode and anode of Zn–air batteries. The mechanism of Zn storage is revealed. As a Zn storage material, phase transition from state I to state III occurs with increasing Zn loading in MoSi2N4. The maximum theoretical capacity of Zn‐loaded MoSi2N4 is 257 mAh g−1. On MoSi2N4 surface as the cathode, the two‐electron mechanism of O2 reduction to ZnO2 is more efficient than general sluggish four‐electron aqueous O2 redox reactions. The work reveals the possibility of MAX phases as the electrodes of Zn–air batteries and the mechanism of Zn storage in 2D MAX layered materials.