Enhanced Cycling Performance of Fe‐doped LiMn2O4 Truncated Octahedral Cathodes for Li‐Ion Batteries

Abstract LiMn 2 O 4 (LMO) with a spinel crystal structure is a promising cathode for next‐generation Li‐ion batteries (LIBs), owing to its low cost and high operating voltage of ∼4.4 V. However, due to the Jahn‐Teller distortion effect, LMO typically exhibits deteriorated cycling performance, owing to the dissolution of Mn into a liquid electrolyte. In this study, Fe‐doped truncated octahedral LMO cathodes with different concentrations were synthesized to improve LMO stability in LIBs. The Fe‐doped truncated octahedral LMO was characterized using X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and X‐ray photoelectron spectroscopy. The Li + ion diffusion coefficients of the cathodes were measured using electrochemical impedance spectroscopy and the galvanostatic intermittent titration technique. Compared to the truncated octahedral undoped LMO, the Fe‐doped LMO cathode with an appropriate amount of dopant exhibited the best LIB performance, with the highest Li + ion diffusivity resulting from the increased oxygen vacancy as the path of Li + ion.