Spatial configuration of interlayer maximizing suppression and conversion efficiency of lithium polysulfides for advanced lithium-sulfur batteries

Shuttle effect of polysulfides and sluggish redox kinetics of sulfur are two tricky problems in lithium -sulfur (Li-S) batteries. Engineering interlayer between sulfur cathode and separator is an innovative approach to alleviate these weaknesses. From the spatial perspective, we validate an efficient interlayer by regulating the stacking configuration composed of a conductive layer (carbonized polyacrylonitrilecarbon nanotube, CPCNT) and catalytic layer (carbonized polyacrylonitrile-selenium, CPSe), forming a hierarchical polysulfide suppression and conversion system. Electrochemical measurements reveal that the contact priority of CPCNT or CPSe on sulfur cathode poses a momentous impact on the overall working efficiency of interlayer. Accordingly, CPSe@CPCNT|S enables Li-S batteries to deliver a specific capacity of up to 760 mAh/g at 1.0C after 500 cycles. Impressively, Li-S batteries endure 250 cycles with 87% capacity retention at 0.2C, even under a sulfur loading of 6.1 mg/cm2. The polysulfide diffusion visualization coupled with finite elemental analyses disclose that CPSe@CPCNT|S configuration shapes a higher diffusion damping towards polysulfides, while maintaining a smooth electron motion pathway from cathode to interlayer for polysulfide conversion, which is the decisive cause of the enhanced electrochemical performance. This research affords a spatial strategy for interlayer design in Li-S batteries and other alkali metal-sulfur batteries. (c) 2024 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).