To overcome the challenge of soluble polysulfides as charge/discharge intermediates in Li-S batteries, researchers at the University of Texas at Austin, with colleagues at Murray State University, have designed highly crosslinked polymer-electrolyte coating layers with electron-donating groups to bind the polysulfides.
Although chemical surface-trap-sites have been proposed to address the polysulfide issue, experimental evidence about the trapping interaction hasn’t been reported.
The Texas team investigated the use of an ester group with a high spatial density to bind the polysulfides. In a paper published in the RSC journal Energy & Environmental Science, the researchers reported spectroscopic evidence for the presence of lithium bonds between the lithium polysulfides and the electron-donating groups for the first time.
They also proposed an electrochemical charge/discharge model which can explain the electrochemical behavior within the insulating polymer layer.
Kyusung Park, Joon Hee Cho, Ji-Hoon Jang, Byeong-Chul Yu, Andreah T. De La Hoz, Kevin M. Miller, Christopher J. Ellison and John B. Goodenough (2015) “Trapping lithium polysulfides of a Li–S battery by forming lithium bonds in a polymer matrix” Energy Environ. Sci. doi: 10.1039/C5EE01809A