Efficient asymmetric diffusion channel in MnCo2O4 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 NH4+is not fully unveiled. In this study, by using MnCo2O4 spinel as a model electrode, the asymmetric ion diffusion channels of MnCo2O4 have been regulated through bond length optimization strategy and investigate the effect of channel size on the diffusion process of NH4+. In addition, the reducing channel size significantly decreases NH4+ adsorption energy, thereby accelerating hydrogen bond formation/fracture kinetics and NH4+ reversible diffusion within 3D asymmetric channels. The optimized MnCo2O4 with oxygen vacancies/carbon nano- tubes composite exhibits impressive specific capacity (219.2 mAh g -1 at 0.1 A g-1) 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-1 and maintains 91.9% capacity after 500 cycles. This finding provides a unique approach for the development of cathode materials in AIBs.