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Towards High Performance Li–S Batteries via Sulfonate‐Rich COF‐Modified Separator

2021; Volume: 33; Issue: 49 Linguagem: Inglês

10.1002/adma.202105178

1521-4095

Jie Xu, Shuhao An, Xianyu Song, Yongjie Cao, Nan Wang, Xuan Qiu, Yu Zhang, Jiawei Chen, Xianli Duan, Jianhang Huang, Wei Li, Yonggang Wang,

Advanced battery technologies research

Lithium-sulfur (Li-S) batteries are held great promise for next-generation high-energy-density devices; however, polysulfide shuttle and Li-dendrite growth severely hinders their commercial production. Herein, a sulfonate-rich COF (SCOF-2) is designed, synthesized, and used to modify the separator of Li-S batteries, providing a solution for the above challenges. It is found that the SCOF-2 features stronger electronegativity and larger interlayer spacing than that of none/monosulfonate COFs, which can facilitate the Li+ migration and alleviate the formation of Li-dendrites. Density functional theory (DFT) calculations and in situ Raman analysis demonstrate that the SCOF-2 possesses a narrow bandgap and strong interaction on sulfur species, thereby suppressing self-discharge behavior. As a result, the modified batteries deliver an ultralow attenuation rate of 0.047% per cycle over 800 cycles at 1 C, and excellent anti-self-discharge performance by a low-capacity attenuation of 6.0% over one week. Additionally, even with the high-sulfur-loading cathode (3.2-8.2 mgs cm-2 ) and lean electrolyte (5 µL mgs-1 ), the batteries still exhibit ≈80% capacity retention over 100 cycles, showing great potential for practical application.