Efficient asymmetric diffusion channel in MnCo 2 O 4 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 4 + is not fully unveiled. In this study, by using MnCo 2 O 4 spinel as a model electrode, the asymmetric ion diffusion channels of MnCo 2 O 4 have been regulated through bond length optimization strategy and investigate the effect of channel size on the diffusion process of NH 4 + . In addition, the reducing channel size significantly decreases NH 4 + adsorption energy, thereby accelerating hydrogen bond formation/fracture kinetics and NH 4 + reversible diffusion within 3D asymmetric channels. The optimized MnCo 2 O 4 with oxygen vacancies/carbon nanotubes 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.