Suppressed Polysulfide Crossover in Li–S Batteries through a High-Flux Graphene Oxide Membrane Supported on a Sulfur Cathode

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• 作者：Mahdokht Shaibani ; Abozar Akbari ; Phillip Sheath ; Christopher D. Easton ; Parama Chakraborty Banerjee ; Kristina Konstas ; Armaghan Fakhfouri ; Marzieh Barghamadi ; Mustafa M. Musameh ; Adam S. Best ; Thomas Rüther ; Peter J. Mahon ; Matthew R. Hill ; Anthony F. Hollenkamp ; Mainak Majumder
• 刊名：ACS Nano
• 出版年：2016
• 出版时间：August 23, 2016
• 年：2016
• 卷：10
• 期：8
• 页码：7768-7779
• 全文大小：597K
• 年卷期：0
• ISSN：1936-086X

文摘

Utilization of permselective membranes holds tremendous promise for retention of the electrode-active material in electrochemical devices that suffer from electrode instability issues. In a rechargeable Li–S battery—a strong contender to outperform the Li-ion technology—migration of lithium polysulfides from the sulfur cathode has been linked to rapid capacity fading and lower Coulombic efficiency. However, the current approaches for configuring Li–S cells with permselective membranes suffer from large ohmic polarization, resulting in low capacity and poor rate capability. To overcome these issues, we report the facile fabrication of a high-flux graphene oxide membrane directly onto the sulfur cathode by shear alignment of discotic nematic liquid crystals of graphene oxide (GO). In conjunction with a carbon-coated separator, the highly ordered structure of the thin (∼0.75 μm) membrane and its inherent surface charge retain a majority of the polysulfides, enabling the cells to deliver very high initial discharge capacities of 1063 and 1182 mAh g_electrode^–1 for electrodes with 70 and 80% sulfur content, respectively, at the practical 0.5 C rate. The very high sulfur utilization and impressive capacity retentions of the high sulfur content electrodes result in some of the highest performance metrics in the literature of Li–S (e.g., electrode capacity of 835 mAh g_electrode^–1 after 100 cycles at 0.5 C with a sulfur content of 80%). We show that the structural order of the shear-aligned GO membrane is key in maintaining good kinetics of the charge transfer processes in Li–S batteries.