The Energy Storage Technology Research Team headed by Professor ZHANG Huamin, Professor LI Xianfeng and Associate Professor ZHANG Hongzhang in Dalian Institute of Chemical Physics (DICP), Chinese Academy of Sciences (CAS) proposed a new lithium-sulfur (Li-S) battery electrolyte.
They added a new kind of electrolyte additives, which include a large size cation, to complex and stabilize the polysulfide in the electrolyte. This new proposed electrolyte could achieve a high energy density Li-S battery with a longer cycle life. The related research has been published on Advanced Functional Materials.
The schematic principle of MEP +complexation in Li-S battery electrolyte. (Image by CHEN Yuqing）
Li-S batteries have been one of the hottest spots of international research in energy storage field, owing to their high energy density and low cost.
However, the practical application of Li-S batteries is still hindered by the rapid capacity of fading. It’s due to the shuttle effect and the disproportionation of polysulfide, and the decomposition of electrolyte and lithium dendrite.
In order to suppress the disproportionation of polysulfide, this research group introduced a kind of large size cation into the Li-S battery. This could complex and stabilize the soluble of polysulfide, which is based on the hard and soft acids and bases (HSAB) theory.
Such electrolyte enables a more stable capability and a longer cycle life: the 5000 mAh Li-S batteries (soft package type) can achieve an initial specific energy over 300 Wh/kg and can maintain almost 70 % after 100 charge/discharge cycles at 1/20 C.
This interesting finding is believed to shed a light on the further development of Li-S batteries.
The above research work was supported by DICP, National Natural Science Foundation of China, Youth Innovation Promotion Association of CAS, Dalian Science and Technology Star Program.