Exploring the Impact of Aluminum Substitution on the Structural Stability of LiMn₂O₄/C Cathode Materials for Lithium-Ion Batteries

Abstract

Aluminum is substituted for manganese in spinel LiMn 2 O 4 (LMO) materials to enhance their structural and electrochemical properties as cathodes for next-generation Li-ion batteries (LIBs). The computation method, in conjunction with the effect of aluminum (Al) substitution, performed a basic optimization of the initial step of this report. The phase purity and Al substitution in the Mn sites were confirmed using powder X-ray diffraction and X-ray photoelectron spectroscopy. Utilizing electron microscopy, we established that the agglomeration of nanosized Al-doped LMO particles with improved grain distribution is dependent on the Al content (X), respectively. The prepared Al-doped LMO cathode exhibited outstanding electrochemical properties depending on the amount of Al substitution. In detail, LiMn 1.975 Al 0.025 O 4 shows a superior high rate performance of 109.5 mAh g −1 at 10C, which corresponds to 81.1% initial capacity retention at 0.1C within the 3.3−4.3 V potential window. LiMn 1.95 Al 0.05 O 4 , a higher Al composition material, shows excellent cycle performance of 93.3% capacity retention after 100 cycles at 0.1C when compared to the initial capacity within the same potential window. The remarkable cycle and rate performance of the Aldoped LMO cathodes can be ascribed to the combined effect of the enhanced structural properties and the well-distributed grains resulting from Mn 3+ /Mn 4+ substitution with Al 3+ ions. Furthermore, from the cyclic voltammetry and impedance characterizations, we identified a highly stable electrochemical reaction and high rate performance in the LMO electrode with 0.025 Al content.