Lithium sulfur batteries become the promising candidate to develop the high-energy density rechargeable battery for electric vehicles and energy storage systems. The theoretical specific energy of the lithium-sulfur battery is 2600 W h/kg, which is much higher than lithium-ion batteries. ¹ However, the commercialization of the lithium sulfur batteries has been hindered by its poor cyclability, short cycle life and low coulombic efficiency.^2-3 The carbon interlayer modified separator provided a promising method to improve the electrochemical performance of lithium-sulfur battery. The carbon layer faced to the cathode blocks polysulfides in the cathode side and restrains the polysulfide shuttling during electrochemical reaction.^4-5

We describe in this work a carbon interlayer modified separator design by the inactive materials from the cathode. The carbon layer coated on the separator is thin and lightweight. In addition, the method using the redistributed inactive materials avoid the added weights of the battery involved. This design will be beneficial to ensure the high-energy density of lithium sulfur batteries. After 150 cycles, the batteries retain a reversible capacity of 644 mAh g^-1at the rate of 0.5 C, showing a low capacity decay of about 0.11% per circle (Figure 1).

Figure 1  Long cycle performance of Li-S batteries with modified separator at 0.5C.

Reference

1. Peled, E.; Gorenshtein, A.; Segal, M.; Sternberg, Y. Rechargeable Lithium-Sulfur Battery. J. Power Sources 1989, 26, 269-271.

2. Mikhaylik, V. Y.; James, R. A. Polysulfide shuttle study in the Li/S battery system. J. Electrochem. Soc. 2004, 151, A1969-A1976.

3. Diao, Y.; Xie, K.; Xiong, S.; Hong, X. Analysis of polysulfide dissolved in electrolyte in discharge-charge process of Li-S battery. J. Electrochem. Soc. 2012, 159, A421-A425.

4. Chung, S. H.; Manthiram, A. Bifunctional Separator with a Light‐Weight Carbon‐Coating for Dynamically and Statically Stable Lithium‐Sulfur Batteries. Adv. Funct. Mater. 2014, 24, 5299-5306.

5. Zhou, G.; Li, L.; Wang, D. W.; Shan, X. Y.; Pei, S.; Li, F.; Cheng, H. M. A Flexible Sulfur‐Graphene‐Polypropylene Separator Integrated Electrode for Advanced Li–S Batteries. Adv. Mater. 2015, 27, 641-647

Acknowledgement: Financial support from the National Science Foundation of China (no. 51272017) is gratefully appreciated.