Tang Ben, Wu Han, Du Xiaofan, Cheng Xiangyang, Liu Xing, Yu Zhe, Yang Jinfeng, Zhang Min, Zhang Jianjun, Cui Guanglei
Qingdao Industrial Energy Storage Research Institute, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, P. R. China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
Small. 2020 Feb;16(5):e1905737. doi: 10.1002/smll.201905737. Epub 2020 Jan 9.
Conventional lithium-sulfur batteries often suffer from fatal problems such as high flammability, polysulfide shuttling, and lithium dendrites growth. Here, highly-safe lithium-sulfur batteries based on flame-retardant electrolyte (dimethoxyether/1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether) coupled with functional separator (nanoconductive carbon-coated cellulose nonwoven) to resolve aforementioned bottle-neck issues are demonstrated. It is found that this flame-retardant electrolyte exhibits excellent flame retardancy and low solubility of polysulfide. In addition, Li/Li symmetrical cells using such flame-retardant electrolyte deliver extraordinary long-term cycling stability (less than 10 mV overpotential) for over 2500 h at 1.0 mA cm and 1.0 mAh cm . Moreover, bare sulfur cathode-based lithium-sulfur batteries using this flame retardant electrolyte coupled with nanoconductive carbon-coated cellulose separator can retain 83.6% discharge capacity after 200 cycles at 0.5 C. Under high charge/discharge rate (4 C), lithium-sulfur cells still show high charge/discharge capacity of ≈350 mAh g . Even at an elevated temperature of 60 °C, discharge capacity of 870 mAh g can be retained. More importantly, high-loading bare sulfur cathode (4 mg cm )-based lithium-sulfur batteries can also deliver high charge/discharge capacity over 806 mAh g after 56 cycles. Undoubtedly, the strategy of flame retardant electrolyte coupled with carbon-coated separator enlightens highly safe lithium-sulfur batteries at a wide range of temperature.
传统锂硫电池常常面临诸如高易燃性、多硫化物穿梭和锂枝晶生长等致命问题。在此，展示了基于阻燃电解质（二甲氧基醚/1,1,2,2-四氟乙基 2,2,3,3-四氟丙基醚）与功能性隔膜（纳米导电碳包覆纤维素无纺布）相结合的高安全性锂硫电池，以解决上述瓶颈问题。研究发现，这种阻燃电解质具有优异的阻燃性和较低的多硫化物溶解度。此外，使用这种阻燃电解质的锂/锂对称电池在1.0 mA cm²和1.0 mAh cm²的条件下，可实现超过2500小时的超长循环稳定性（过电位小于10 mV）。而且，使用这种阻燃电解质与纳米导电碳包覆纤维素隔膜的基于裸硫阴极的锂硫电池，在0.5 C下循环200次后仍可保持83.6%的放电容量。在高充放电速率（4 C）下，锂硫电池仍显示出约350 mAh g⁻¹的高充放电容量。即使在60°C的高温下，仍可保持870 mAh g⁻¹的放电容量。更重要的是，基于高负载裸硫阴极（4 mg cm⁻²）的锂硫电池在56次循环后也能提供超过806 mAh g⁻¹的高充放电容量。毫无疑问，阻燃电解质与碳包覆隔膜相结合的策略为宽温度范围内的高安全性锂硫电池提供了启示。
