A novel Mo@VN/V2O3-Co3O4 composite as a stable catalyst for potassium‑oxygen batteries with excellent performance

Abstract

The potassium‑oxygen battery (KOB) as the only new system in metal-air batteries does not generate singlet oxygen (¹O₂). It is a novel high-energy-density storage device which has attracted widespread attention. However, the low efficiency of potassium ion and oxygen transfer in KOB, along with slow kinetics, results in poor cycling stability. For this reason, a new composite catalytic material with a multicomponent Mo@VN/V₂O₃-Co₃O₄ in cathode of KOB has been designed and prepared. The homologous heterostructure formed between VN and V₂O₃ exhibits a good lattice match, enhancing the carrier mobility and electrochemical activity of the electrode, thereby increasing the discharge capacity of the KOB. The multicomponent active interface formed between Co₃O₄ and VN/V₂O₃ stimulates more electrons to participate in redox reactions, and the synergistic catalytic effect promotes the reversible decomposition of KO₂, improving the cycle life of the KOB. The doping of Mo enables Mo⁶⁺ to enter the V₂O₃ lattice, replacing some V^δ+, which creates crystal defects that facilitate the rapid diffusion of K⁺ and O₂ in the electrode. Final, the Mo@VN/V₂O₃-Co₃O₄ is used as a cathode catalyst of KOB, shown discharge specific capacity of 1899.61 mAh·g⁻¹ with a cycle life >170 cycles.