Functional Hybrid Separator for Advanced Lithium-Sulfur Batteries

The lithium-sulfur (Li-S) battery is considered one of the most promising candidates for next-generation rechargeable batteries due to its high theoretical specific energy of 2.6 kWh kg−1, which is up to 5 times higher compared to state-of-the-art lithium-ion batteries. Additionally, sulfur has the enormous advantages of being inexpensive, environmentally benign and naturally abundant. However, its commercialization has been hindered due to the insulating nature of sulfur and the poor cycling stability, mainly caused by the polysulfide shuttle phenomenon.[1]

In order to tackle these issues, we focus on the development of functional hybrid separators by a straightforward coating modification of a commercial separator with porous carbon materials (Figure 1).[2] Particularly, Li-S cells with a mesoporous carbon-coated separator retain capacities of the order of 700 mAh g–1 after 500 cycles at 1 C, despite the use of a simple cathode mixture containing a high sulfur/non-porous carbon. The enhanced electrochemical performance of the Li-S cells is attributed to the unique features of the mesoporous carbon-coating, which i) effectively reduces the resistance of the sulfur cathode, ii) prompts fast electron/lithium ion transport through the carbon network, iii) successfully sequestrates, stores and maintains available the sulfur active material for further reutilization and, iv) buffers the large volume change during sulfur/Li2S conversion reaction.

Our work highlight the importance of the rational design of modified separators with mesoporous carbon materials and this proof-of-concept may bring reliability for high performance Li–S batteries.

Figure 1. (a) Schematic configuration of the Li–S cells with a mesoC-coated separator. The cell configuration is composed of, from left to right, a sulfur cathode, the functional hybrid separator and a lithium anode. (b) Digital images of the mesoC-coated separator. (c) Long-term cycling performance of Li–S cells with a mesoC-coated separator at 0.5, 1 and 2 C (1 C = 1672 mA g–1).    

Contact person:

Dr. Lars Giebeler

l.giebeler@ifw-dresden.de  

Publications:  

J. Balach, T. Jaumann, M. Klose, S. Oswald, J. Eckert, L. Giebeler: Mesoporous Carbon Interlayers with Tailored Pore Volume as Polysulfide Reservoir for High-Energy Lithium-Sulfur Batteries, The Journal of Physical Chemistry C 119 (2015), S. 4580-4587. URL

J. Balach, T. Jaumann, M. Klose, S. Oswald, J. Eckert, L. Giebeler: Functional Mesoporous Carbon-Coated Separator for Long-Life, High-Energy Lithium-Sulfur Batteries, Advanced Functional Materials 25 (2015), S. 5285-5291. URL

U. Stoeck, J. Balach, M. Klose, D. Wadewitz, E. Ahrens, J. Eckert, L. Giebeler: Reconfiguration of lithium sulphur batteries: "Enhancement of Li-S cell performance by employing a highly porous conductive separator coating", Journal of Power Sources 309 (2016), S. 76-81. URL