Abstract
The practical application of lithium-sulfur battery (LSB) is limited owing to its poor cycling stability stemming from the 'shuttle effect' or the migration of soluble polysulfide intermediates (Li2Sn, 4 ≤ n ≤ 8). Numerous strategies have been proposed to solve this issue by designing host materials to control polysulfides within the cathode, developing electrolytes to be able to reduce polysulfide solubility, and adding interlayers to block polysulfide migration to the anode.[1] However, these concepts are far from practical operation. Herein, we introduce the modified polyethylene separator with an objective for reducing the 'shuttle effect'. The commercial hydrolyzed polyethylene (HyPE) separator was firstly functionalized with carboxylic acid (-COOH) groups before grafting polyaniline (PANI) molecules on its surface via an amide coupling process for which the -COOH on the HyPE surface can chemically react with imine groups (-N=) of the PANI structure. Interestingly, the battery with the modified PANI separator can enhance the specific capacity and coulombic efficiency for 10 and 15%, respectively, as compared with the conventional cell configuration using the PE seperator. Owing to the chemical interaction between the imine group of the quinoid ring in the structure of PANI and the lithium polysulfide molecules, the polysulfide species are retained on the PANI/HyPE surface until Li2S is fully formed.[2] This idea can improve the sulfur utilization and enhance the stability of the lithium-sulfur batteries.
References:
Yin, L., et al., A functional interlayer as a polysulfides blocking layer for high-performance lithium–sulfur batteries. New Journal of Chemistry, 2018. 42(2): p. 1431-1436.
Zhong, M.-e., et al., Accelerated polysulfide redox kinetics revealed by ternary sandwich-type S@Co/N-doped carbon nanosheet for high-performance lithium-sulfur batteries. Carbon, 2018. 128: p. 86-96.
Figure 1