BIT Has Made New Progress in the Field of Lithium-Sulfur Battery Negative Electrode Protection Strategies

  Recently, the top international material journal "Advanced Materials" (impact factor 27.4) reported the research progress of Huang Jiaqi's research group at the Advanced Research Institute of Multidisciplinary Science of Beijing Institute of Technology in the protection of lithium-sulfur batteries lithium negative electrodes. Their research results were published online under the title of "Shielding Polysulfide Intermediates by an Organosulfur-Containing Solid Electrolyte Interphase on the Lithium Anode in Lithium–Sulfur Batteries". The first author of this work is Wei Junyu, a postgraduate student at the School of Materials Science and Engineering / Advanced Research Institute of Multidisciplinary Science of Beijing Institute of Technology.

  Sulfur batteries are one of the electrochemical energy storage systems that have great development potential. However, due to the highly active soluble polysulfides and unstable lithium negative electrodes, lithium-sulfur batteries have been limited by problems such as short cycle life and low coulombic efficiency, making it difficult for practical applications. Therefore, the construction of an SEI that can inhibit the side reactions between polysulfides and lithium metal is very important for achieving stable and efficient cycling of lithium-sulfur batteries.
In this work, by introducing 3,5-bis(trifluoromethyl)thiophenol (BTB) as an electrolyte additive, a solid electrolyte interface (SEI) containing organic sulfur that can "shield" polysulfides was designed to protect the lithium anode. The stability and cycle life of lithium-sulfur batteries were improved under practical conditions.

  According to visual experiments and XPS, it is verified that the SEI containing organic sulfur, which is involved in the regulation of BTB, can effectively inhibit the side effects of polysulfides and metallic lithium, and its components can stably exist in the SEI.

Figure 1. Visualization experiment and XPS's polysulfide "shielding" ability verification of SEI

  SEI conducted further evaluations, it shows that compared with conventional SEI, SEI containing organic sulfur has effectively improved battery stability and cycle life. According to the change of voltage with cycle and the comparison of deposition morphology, it is shown that SEI containing organic sulfur can improve the uniformity of lithium deposition in lithium-sulfur batteries and reduce the consumption of lithium metal.

Figure 2. Electrochemical performance and deposition morphology of lithium-lithium symmetric battery

Figure 3. Electrochemical performance and deposition morphology of lithium-sulfur batteries

  Through the disassembly and analysis of the full battery after the cycle, the composition of the SEI containing organic sulfur was further explored. It was found that SEI containing organic sulfur contains Ph–S−, a reaction product of BTB and metallic lithium. The Ph-S- component can "shield" the polysulfide through electrostatic repulsion, thereby effectively inhibiting the side reaction between lithium metal and polysulfide, and protecting the lithium metal negative electrode.

Figure 4. Schematic diagram of the composition, formation and effect of SEI containing organic sulfur

  This work reveals the role of the organic components of SEI in lithium-sulfur batteries in protecting lithium metal anodes under practical conditions.

  Huang Jiaqi is a professor and a doctoral supervisor of Advanced Research Institute of Multidisciplinary Science of Beijing Institute of Technology, and a member of Jiusan Society. He mainly works on energy interface chemistry research. In Angew. Chem. Int. Ed. , J. Am. Chem. Soc. , Adv. Mater. , Adv. Funct. Mater. , Sci. Bull. He has published more than 100 research papers with h factor of 72, among which more than 40 are highly cited papers on ESI. He was selected into the first China Association for Science and Technology Young Talents Support Program, won the Hou Debang Chemical Science and Technology Youth Award of the Chinese Society of Chemical Industry, the Young Particle Science Award of the Chinese Society of Particulates, the National Ten Thousand Talents Program Young Top Talent, Clarivate Analytics Cited Scientist in 2018 and 2019 and so on.

  Paper details: Jun-Yu Wei, Xue-Qiang Zhang, Li-Peng Hou, Peng Shi, Bo-Quan Li, Ye Xiao, Chong Yan, Hong Yuan, Jia-Qi Huang *. Shielding Polysulfide Intermediates by an Organosulfur‐Containing Solid Electrolyte Interphase on the Lithium Anode in Lithium–Sulfur Batteries, Advanced Materials, 2020, 2003012.
Paper: https: //onlinelibrary. wiley. com/doi/full/10.1002/adma. 202003012


News Source: Advanced Research Institute of Multidisciplinary Science 
Editor: Zhu Qianyun Audit: Tang Shuiyuan