Regulating solid electrolyte interphase with amide-rich carbon nanotube interlayer for high power lithium-sulfur battery

Abstract

Lithium-Sulfur (Li-S) batteries are considered a promising energy storage technology for their high energy density and low material cost. However, challenges facing this system include the shuttle effect and insulating nature of sulfur associated with the cathode, which shorten cycle life and limit capacity. Moreover, the lithium metal anode may suffer from continuous parasitic reactions with the electrolyte. Here, a multifunctional amide-multiwalled carbon nanotube (A-MWCNT) interlayer is fabricated with a free-standing, 3D-like structure for Li-S batteries. Through in situ X-ray diffraction (XRD) and impedance measurements, amide-rich interlayers are found promoting formation of conductive solid electrolyte interphase (SEI) layers. Thickness reduction of the compact SEI layer, suggested by the impedance analysis, is attributed to higher electrolyte retention capability of the A-MWCNT interlayer. The Li symmetric cell equipped with this interlayer exhibits low overpotential and prolonged cycle life, resulting from the formation of more conductive and stable SEI. The amide-rich interlayer is also found to achieve substantial suppression of the shuttle effect. Li-S batteries equipped with this interlayer, in turn, are shown to exhibit high initial capacity, low decay rate, and afford high current rate up to 4C. These results demonstrate that the amide-rich interlayer can perform a multitude of functionality and enable Li-S batteries for high power applications.