The electrochemical performance of sodium-ion-modified spinel LiMn2O4 used for lithium-ion batteries

The spinel LiMn2O4 cathode material has been considered as one of the most potential cathode active materials for rechargeable lithium ion batteries. The sodium-doped LiMn2O4 is synthesized by solid-state reaction. The X-ray diffraction analysis reveals that the Li1-x Na (x) Mn2O4 (0 a parts per thousand currency signaEuro parts per thousand x a parts per thousand currency signaEuro parts per thousand 0.01) exhibits a single phase with cubic spinel structure. The particles of the doped samples exhibit better crystallinity and uniform distribution. The diffusion coefficient of the Li0.99Na0.01Mn2O4 sample is 2.45 x 10(-10) cm(-2) s(-1) and 3.74 x 10(-10) cm(-2) s(-1), which is much higher than that of the undoped spinel LiMn2O4 sample, indicating the Na+-ion doping is favorable to lithium ion migration in the spinel structure. The galvanostatic charge-discharge results show that the Na+-ion doping could improve cycling performance and rate capability, which is mainly due to the higher ion diffusion coefficient and more stable spinel structure.