A novel mulberry-like Ag/AgCl@TiO2/V2O5-x composite as a stable catalyst for long-life potassium‑oxygen batteries

The potassium‑oxygen battery is a new type of metal-air battery with potassium metal as the anode and obtaining O2 from the air as a reactant for the cathode. In current, the focus of research about metal-air battery has gradually shifted to potassium‑oxygen battery due to its ideal energy density and green environmental protection. However, potassium‑oxygen batteries suffer from low potassium ion and oxygen transfer efficiency resulting in suboptimal cycling stability. For this purpose, a novel mulberry-like Ag/AgCl@TiO2/V2O5-x composite cathode catalyst is designed in order to form an active interface consisting of TiO2, V2O5-x, Ag and AgCl. TiO2 increases the rate and capacity of K+ insertion, and the V2O5-x with anoxic structure attracts more O2 to O2− for facilitating its binding to K+ and promoting the formation of discharge product KO2. In addition, AgCl has a high OER catalytic activity due to the large difference in electronegativity between these two elements which accelerates the KO2 decomposition. While, the addition of Ag allows more electrons to be transferred from the current collector to the electrode surface so as to compensate for the poor conductivity of AgCl. Therefore, the potassium‑oxygen batteries showcase a high discharge specific capacity of 1391.72 mAh·g−1 with a 80 time long cycle life.