Cobalt doped spinel LiMn2O4 cathode toward high-rate performance lithium-ion batteries

Great efforts have been devoted to improving the cycling stability and the high-rate performance of spinel LiMn 2 O 4 cathode. Herein, we demonstrate that Co doping can improve the electrochemical performance of spinel LiMn 2 O 4 . We elucidate the atomic position of Co in spinel LiMn 2 O 4 configuration and the stability improvement mechanism of the Co-doped LiMn 2 O 4 cathode by using the state-of-art spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM). The results show that the Co 3+ ions occupy the Mn octahedral 16d sites to reconstruct a more robust LiCo x Mn 2−x O 4 framework, which is beneficial for stabilizing the LiMn 2 O 4 crystal structure by ameliorating Mn dissolution and inhibiting Jahn-Teller distortion. Concomitantly, the doped Co atoms can offer short path lengths for Li + ions intercalation and deintercalation that leads to accelerated Li + diffusion kinetics. The as-designed optimal LiCo 0.05 Mn 1.95 O 4 presents a respectable capacity retention of 83.81 % after 1000 cycles at 10C (1C = 148 mAh g −1 ), with an initial discharge capacity of 86.31 mAh g −1 . Especially, excellent capacity retention of 78.52 % is obtained after 1000 cycles even at a high current rate of 15C. Our research shed light on the microscopic mechanism of Co doping on the cycling stability enhancement of spinel LiMn 2 O 4 toward high-rate performance LIBs .