High-energy-density rechargeable batteries play an important role in our daily life by supplying energy for mobile phones, laptops, and electric vehicles. Li–S batteries have an ultrahigh theoretical energy density of 2600 Wh kg −1 , allowing them to significantly outperform existing Li ion batteries. Therefore, they are recognized as promising next-generation rechargeable battery systems.
However, the cycling lifespan of high-energy-density Li–S batteries is far from satisfactory, and its main limiting factors and underlying mechanism have not yet been clarified. Therefore, evaluating high-energy-density Li–S batteries is of great importance for us to understand their working mechanism and design rational promotion strategies.
Recently, a research group led by Dr. Bo-Qian Li and Prof. Jia-Qi Huang from Beijing Institute of Technology performed a systematic evaluation on 400 Wh kg −1 Li–S pouch cells. They found that considerable lithium polysulfides existed in the electrolyte even at the end of the first cycle of discharge or charge despite the actual high specific capacities, which is very different from our common understanding of coin cells. Part of the sulfur on the cathode could not participate in cell discharge, on the contrary, the discharge product Li 2 S could be charged with high reversibility. Meanwhile, drastic morphological changes were observed on the Li metal anode as expected. Nevertheless, there remained a substantial amount of active Li to support the following cycles. These results suggest that the actual capacity loss compared with the theoretical value is mainly attributed to the dissolved sulfur species in the electrolyte rather than the depletion by the Li anode.
“This work demonstrates unique Li–S electrochemical behaviors under practical conditions and inspires us to further investigate high-energy-density Li–S batteries,” says Dr. Li.
These results have been published in the Journal of Energy Chemistry .
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This work was supported by the Beijing Natural Science Foundation (JQ20004), the National Natural Science Foundation of China (U1801257), and the Scientific and Technological Key Project of Shanxi Province (20191102003).
About the journal
The Journal of Energy Chemistry is a publication that mainly reports on creative researches and innovative applications of chemical conversions of fossil energy, carbon dioxide, electrochemical energy and hydrogen energy, as well as the conversions of biomass and solar energy related with chemical issues to promote academic exchanges in the field of energy chemistry and to accelerate the exploration, research and development of energy science and technologies.
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DOI
10.1016/j.jechem.2021.07.010
Journal of Energy Chemistry