Xian Wu,Lishuang Fan,Yue Qiu,Maoxu Wang,Junhan Cheng,Bin Guan,Zhikun Guo,Naiqing Zhang,Kening Sun
Graphical Li—pass, S—no chance : An ion-selective and cheap separator is required to construct high-performance lithium–sulfur batteries. To address the problem, a Celgard separator modified with Prussian blue is prepared through a simple growth method. This innovative separator allows unhindered diffusion of Li ions but hinders diffusion of polysulfides without affecting the performance. Application of Li–S batteries has been restricted because of their major problem, that is, shuttling of soluble polysulfides between electrodes, which results in serious capacity fading. For the development of high-performance Li–S batteries, we first time utilize a simple growth method to introduce a Prussian blue (PB)-modified Celgard separator as an ion-selective membrane. The unique structure of PB could effectively suppress the shuttle of polysulfides but scarcely affect the transfer ability of lithium ions, which is beneficial to achieve high sulfur conversion efficiency and capacity retention. The Li–S battery with PB-modified Celgard separator has an average capacity decay of only 0.03 % per cycle at 1 C after 1000 cycles.
The rapid capacity loss caused by the shuttling effect of polysulfides is one of the great challenges of Li–S batteries. In this work, we adopted a simple solid-phase sintering method to synthesize titanium disulfide (TiS2) and further demonstrated it as a superior modifier of separators for Li–S batteries. Two commonly adopted modification processes of separators, including vacuum filtration (VF) and slurry casting (SC) have been used to prepare TiS2/Celgard separators. TiS2-VF/Celgard can better restrain the polysulfide shuttling effect compared with TiS2-SC/Celgard. A TiS2-VF/Celgard-based Li–S battery has a reversible capacity of 771.6 mA h g−1, with a capacity retention of 645.6 mA h g−1 after 500 cycles at 2.0 C, corresponding to a capacity fading rate of ∼0.033% per cycle. This study has shown the potential of TiS2 as a multifunctional modifier of separators for high performance and long cycle life Li–S batteries.
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