Atomic insights into surface orientations and oxygen vacancies in the LiMn2O4 cathode for lithium storage

Surface anisotropy of spinel LiMn2O4 crystal is of significance for strengthening the lithium storage. In this work, we investigate the evolutions of surface orientations and oxygen vacancies in the LiMn2O4 cathode materials by the spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM) technique. Firstly, the {111} lattice planes appear in the formed LiMn2O4 octahedra, and then the {110} and {001} crystal planes are observed in the subsequent truncated octahedral at a higher temperature or a longer annealing time. The LiMn2O4 crystals with dominated {111} and {110} planes and an appropriate amount of oxygen vacancies exhibits a superior cycling performance and rate performance, suggesting a synergistic effect of surface orientation and concentration of oxygen vacancies achieves an enhanced electrochemical performance. The introduction of oxygen vacancies can accelerate the diffusion of lithiumions along {110} plane and strengthen the rate performance of LiMn2O4, as elucidated by the combination of Cs-STEM observation, X-ray photoelectronic spectra analysis and property measurements. ? 2021 Elsevier B.V. All rights reserved.

Automated summary

The study investigates the evolution of surface orientations and oxygen vacancies in LiMn2O4 cathode materials using Cs-STEM technique. LiMn2O4 crystals with dominated {111} and {110} planes and an appropriate amount of oxygen vacancies exhibit superior cycling performance and rate performance, indicating a synergistic effect of surface orientation and oxygen vacancies on enhanced electrochemical performance.