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Systematic Effect for an Ultralong Cycle Lithium–Sulfur Battery

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journal contribution
posted on 11.11.2015, 00:00 by Feng Wu, Yusheng Ye, Renjie Chen, Ji Qian, Teng Zhao, Li Li, Wenhui Li
Rechargeable lithium–sulfur (Li–S) batteries are attractive candidates for energy storage devices because they have five times the theoretical energy storage of state-of-the-art Li-ion batteries. The main problems plaguing Li–S batteries are poor cycle life and limited rate capability, caused by the insulating nature of S and the shuttle effect associated with the dissolution of intermediate lithium polysulfides. Here, we report the use of biocell-inspired polydopamine (PD) as a coating agent on both the cathode and separator to address these problems (the “systematic effects”). The PD-modified cathode and separator play key roles in facilitating ion diffusion and keeping the cathode structure stable, leading to uniform lithium deposition and a solid electrolyte interphase. As a result, an ultralong cycle performance of more than 3000 cycles, with a capacity fade of only 0.018% per cycle, was achieved at 2 C. It is believed that the systematic modification of the cathode and separator for Li–S batteries is a new strategy for practical applications.