Electrochemical evaluation of Co-Al dual-doped LiMn₂O₄ spinels synthesized via hydrothermal method

In order to improve the cycling performance of LiMn₂O₄-based cathode materials, the Co-Al dual-doped Li_1.088Al_0.037Co_0.028Mn_1.847O₄ cathode materials were prepared by hydrothermal method followed by heat treatment. XRD patterns reveal that the dual-doped Al and Co in spinel lithium manganese oxide does not affect the Fd3m space group of the cathode materials. SEM shows that all Li_1.088Al_0.037Co_0.028Mn_1.847O₄ samples exhibit a uniform, nearly cubic structure morphology with narrow size distribution. The effect of the dual-doped Co-Al on the electrochemical performance of Li_1.088Al_0.037Co_0.028Mn_1.847O₄ was investigated by galvanostatic charge-discharge test, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results demonstrate that the synthesized Co-Al dual-doped LiMn₂O₄ materials gain better cycling stability and rate performance, which retains a capacity retention of 95.9% after 100 cycles at 1 C and deliver a higher capacity of 77.5 mAh·g^-1 at 8 C. This indicates superior cycling and rate performance compared with pristine one and single-phase doping of Al and Co.