A Separator with Double Coatings of Li4Ti5O12 and Conductive Carbon for Li-S Battery of Good Electrochemical Performance

Abstract

The market demand for energy pushes researchers to pay a lot of attention to Li-S batteries. However, the ‘shuttle effect’, the corrosion of lithium anodes, and the formation of lithium dendrites make the poor cycling performances (especially under high current densities and high sulfur loading) of Li-S batteries, which limit their commercial applications. Here, a separator is prepared and modified with Super P and LTO (abbreviation SPLTOPD) through a simple coating method. The LTO can improve the transport ability of Li+ cations, and the Super P can reduce the charge transfer resistance. The prepared SPLTOPD can effectively barrier the pass-through of polysulfides, catalyze the reactions of polysulfides into S2−, and increase the ionic conductivity of the Li-S batteries. The SPLTOPD can also prevent the aggregation of insulating sulfur species on the surface of the cathode. The assembled Li-S batteries with the SPLTOPD can cycle 870 cycles at 5 C with the capacity attenuation of 0.066% per cycle. When the sulfur loading is up to 7.6 mg cm−2, the specific discharge capacity at 0.2 C can reach 839 mAh g−1, and the surface of lithium anode after 100 cycles does not show the existence lithium dendrites or a corrosion layer. This work provides an effective way for the preparation of commercial separators for Li-S batteries.