LiMn2O4 as strong polysulfides adsorption carrier for high performance lithium‑sulfur batteries

Abstract

Spinel LiMn2O4 was introduced into cathode for lithium‑sulfur (Li-S) batteries due to its stable structure, low price, good lithium ion conductivity and much active sites of Mn atoms which could capture polysulfides. Ultraviolet/visible absorption, Fourier transform infrared and X-ray photoelectron spectroscopies verified strong adsorption of Li2S6 by LiMn2O4. It could be explained by following possible adsorption mechanism that part Mn4+ on the surface of LiMn2O4 was reduced and transformed Mn3+ and Mn2+, at the same time, some S62− was oxidized and transformed Li2S6−x (1<x<6) which was adsorbed on S/LiMn2O4 electrode. In addition, S/LiMn2O4 electrode could exhibit the capacities of 924.9 and 728.0mAhg−1 at 1st and 300th cycle at 0.5C, respectively, exceeding S/Acetylene black electrode's capacities of 722.1 and 518.9mAhg−1 in sequence. Rate property tests suggested that S/LiMn2O4 electrode had higher capacity than S/C electrode, which as well indicated that LiMn2O4 had better help in limiting polysulfides and promoting utilization of sulfur.