Ultra-fast NH4+ Storage: Strong H Bonding between NH4+ and Bi-layered V2O5

It is accepted that the performance of batteries is dominated by the properties of their electrode materials. However, this maxim is built from the practice that the majority of research efforts have been directed toward batteries that use metal ions as the charge carriers. Herein, we show that the use of NH4+ results in battery performance governed by the chemical nature of the ion-electrode interaction. Specifically, we show that H bonding between NH4+ and a bi-layered V2O5 electrode is coupled with prominent pseudocapacitive behavior. The importance of the H bonding is demonstrated by comparing the storage of NH4+ in V2O5 with storage of K+. In addition to having a higher capacity and longer life of 30,000 cycles, NH4+ storage is overwhelmingly more pseudocapacitive than the K+ storage. Furthermore, first-principle calculations reveal an intriguing ion rotation-diffusion mechanism of NH4+ inside the V2O5 structure, akin to swinging on monkey bars.