Efficient asymmetric diffusion channel in MnCoO spinel for ammonium-ion batteries.

Transition metal oxides ion diffusion channels have been developed for ammonium-ion batteries (AIBs). However, the influence of microstructural features of diffusion channels on the storage and diffusion behavior of NH is not fully unveiled. In this study, by using MnCoO spinel as a model electrode, the asymmetric ion diffusion channels of MnCoO have been regulated through bond length optimization strategy and investigate the effect of channel size on the diffusion process of NH. In addition, the reducing channel size significantly decreases NH adsorption energy, thereby accelerating hydrogen bond formation/fracture kinetics and NH reversible diffusion within 3D asymmetric channels. The optimized MnCoO with oxygen vacancies/carbon nanotubes composite exhibits impressive specific capacity (219.2 mAh g at 0.1 A g) and long-cycle stability. The full cell with 3,4,9,10-perylenetetracarboxylic diimide anode demonstrates a remarkable energy density of 52.3 Wh kg and maintains 91.9% capacity after 500 cycles. This finding provides a unique approach for the development of cathode materials in AIBs.