Genetic engineering of porous sulfur species with molecular target prevents host passivation in lithium sulfur batteries

Abstract

High-specific-area host materials have been widely used in lithium-sulfur (Li–S) batteries to trap ploysulfides for high sulfur utilization and excellent operation stability. However, uncontrollable deposition of non-conductive Li2S on host materials tends to occur on the high-loading hosts, causing disastrous surface passivation during the long-term operation. One effective way to tackle this problem is to control the nucleation and growth of sulfur species during cycling by engineering the structure of electrodeposited insulating Li2S to generate open channels for charge transport. In this work, we report a rationally designed porous structure sulfur cathode with homogeneous sulfur loading by incorporating polyisoprene@sulfur into the interlayers of highly conductive Ti3C2Tx, in which the backbone of the polyisoprene and the interlayers of Ti3C2Tx support the porous structure sulfur species, and the unsaturated and functionalized bonds including C–C and C–O regulate the nucleation and heterogeneous growth of Li2S to prevent arbitrary Li2S accumulation on host surface. As a result, three-dimensional porous Li2S islands are achieved during discharge for free electron and ion transfer, thus effectively suppressing the surface passivation of the host. This conceptually novel design leads to remarkable improvement of the cycling performances with a capacity retention of 71% over 650 cycles. This report opens up an efficient avenue for controling the deposition of S/Li2S on the high-surface-area hosts to build high-performance Li–S batteries.