Sodium and Potassium Storage Behaviour in AgNbO 3 Perovskite

In this work, we report on the investigation the perovskite‐type AgNbO 3 as a model negative electrode for sodium and potassium systems. We demonstrated that during the initial discharge, regardless of the inserted cation, the material undergoes an activation mechanism that induces a crystalline‐to‐amorphous transition. This transition, in turn, leads to an enhancement of the electrode capacity. At 5 A g −1 sodium‐ion AgNbO 3 and Potassium‐ion AgNbO 3 display capacities of 81 mAh g −1 and 60 mAh g −1 , respectively. Furthermore, both electrodes display good cycling stability and efficiency over 350 cycles at 1 A g −1 .