Lithium-sulfur batteries show promise for replacing lithium-ion ones. Li-S offers energy densities of about 500 Whr/kg, vs. 150 to 200 Whr/kg for Li-ion versions. Further, Li-S batteries have been demonstrated to withstand 1,500 charge/discharge cycles.
New research might bring the technology closer to commercialization. In the journal APL Materials, from AIP Publishing, a team of researchers led by Dr. Vasant Kumar at the University of Cambridge and Professor Renjie Chen at the Beijing Institute of Technology describe their design of a multifunctional sulfur cathode at the nanolevel to address performance-related issues such as low efficiency and capacity degradation.
The researchers essentially wrapped a sheet of graphene around a multifunctional sulfur electrode. They employed a metal-organic framework (MOF) as a template to form a conductive porous carbon cage.
“Our carbon scaffold acts as a physical barrier to confine the active materials within its porous structure,” explained Kai Xi, a research scientist at Cambridge, as quoted at Newswise. “This leads to improved cycling stability and high efficiency.” They also discovered that by further wrapping the sulfur-carbon energy storage unit within a thin sheet of flexible graphene speeds the transport of electrons and ions.
Xi said that in the future, “We’ll focus on fabricating hybrid free-standing sulfur cathode systems to achieve high-energy density batteries, which will involve tailoring novel electrolyte components and building lithium ‘protection layers’ to enhance the electrochemical performance of batteries.”
The article, “Graphene-wrapped sulfur/metal organic framework (MOF)-derived microporous carbon composite for lithium sulfur batteries,” is authored by Renjie Chen, Teng Zhao, Tian Tian, Shuai Cao, Paul R. Coxon, Kai Xi, David Fairen-Jimenez, R. Vasant Kumar, and Anthony K. Cheetham. It can be accessed here.
