The Heteropolar Structure Design and Performance Research of Sulfur Composite Cathode Materials
College of Materials Science and Engineering, Zhejiang University of Technology
Abstract: Rechargeable lithium sulfur (Li-S) batteries have recently become one of the more exciting energy storage systems due to the low cost and high specific energy of sulfur cathode. But the practical application of Li-S batteries is still hindered by many challenges: (1) poor electronic/ionic conductivity of sulfur and lithium sulfide, (2) large volumetric expansion (80%) of sulfur upon lithiation, (3) dissolution of intermediate lithium polysulfides (Li2Sx, x>3) in the electrolyte.
In order to solve these problems, our group combined the elemental sulfur with porous Pt nanoparticles, conducting oxides Ti4O7, boron or nitrogen doped carbon, phosphides doped carbon nanosheets serving as C/S composite materials in the past few years. Besides, considering the nonpolar nature of sulfur and polar nature of discharge products Li2Sx and Li2S, our group proposed heteropolar design to obtain high-performance sulfur cathode. One side, the nonpolar surface of framework material can enhance the binding force with sulfur, improve the sulfur content and then increase the conductivity. On the other side, the polar surface of framework material can restrain the dissolution of Li2Sx, suppress the shuttle effect and increase the binding force between framework material and Li2S. Hence, we prepared a series of nonconductive metal oxides nanoparticles decorated porous carbon nanoflakes materials. Based on the adsorption test and DFT calculations, we firstly verified the monolayered chemisorptions behavior of Li2S and proposed the design principle for adsorption enhanced C/S composites.
Biography: Prof. Xinyong Tao, received his ph. D degree in Department of Materials Science and Engineering, Zhejiang University in 2007. Then, he did postdoctoral research at University of South Carolina from 2007 to 2008 and went to Stanford University as a visiting scholar from 2014 to 2015. He joined the Department of Materials Science and Engineering, Zhejiang University of Technology as professor at 2008. His research interests focus on the preparation and energy storage properties investigation of carbon-based functional materials, advanced lithium secondary battery and new energy storage materials. He has authored and co-authored about 175 peer-reviewed journal articles and has earned over 4000 citations. He was selected as “New century excellent talents in university”, “Qianjiang specially-appointed professor”, “New century 151 talent project (Level 1)” and acquired 2017 China National Funds for Excellent Young Scientists.