Nanostructured Metal Oxide Based Interlayers for Lithium-Sulfur Batteries

Abstract

High-energy lithium-sulfur batteries are now earmarked as a viable means to meet the ever-rising demands of large-scale utilities and long-range electric vehicle.1 However, their commercialization has not come true yet due to the issues with the dissolution and diffusion of intermediate polysulfides in liquid organic electrolytes, which cause serious capacity degradation and low Coulombic efficiency. To solve these problems, a layer of material with nano-architecture, made from tiny metal oxides, is placed on the surface of sulfur cathode. As a proof of concept, zinc oxides (ZnO) nanowire arrays are grown on three-dimensional (3D) nickel foam and are used as an interlayer to enhance the electrochemical performance of Li-S batteries2. It is demonstrated that ZnO nanowires play a key role in chemically capturing polysulphides and remarkably mitigating capacity decay. After successful results, the foam was replaced by a lightweight carbon fibre mat to reduce the battery’s overall weight. Based on a similar design principle，a praline-like flexible interlayer consisting of titanium oxide (TiO2) nanoparticles and carbon nanofibers which allows the chemical adsorption of polysulfides to a robust conductive film. TiO2 nanoparticles, serving as anchors, can chemically detect and intercept polysulfides in-situ3. The porous conductive carbon backbone helps in the physical absorption of polysulfides and provides redox reaction sites to allow the polysulfides to be reused. A significant enhancement in cycle stability and rate capability has been achieved by incorporating our interlayer with a sulfur/carbon nanotube composite cathode. These results herald a new approach to advanced lithium–sulfur batteries using nanostructured metal oxide based interlayers. Reference 1. Chen, R., Zhao, T. and Wu, F. Chemical Communications, 2015, 51(1), 18-33. 2. Zhao, T., Ye, Y., Peng, X., Divitini, G., Kim, H.K., Lao, C.Y., Coxon, P.R., Xi, K., Liu, Y., Ducati, C. and Chen, R., Advanced Functional Materials, 2016. 26(46), 8418-8426. 3. Zhao, T., Ye, Y., Lao, C.Y., Divitini, G., Coxon, P.R., Peng, X., He, X., Kim, H.K., Xi, K., Ducati, C. and Chen, R., Small, 2017, 13(40), p.1700357. Figure 1