Fu Yongsheng, Wu Zhen, Yuan Yifei, Chen Peng, Yu Lei, Yuan Lei, Han Qiurui, Lan Yingjie, Bai Wuxin, Kan Erjun, Huang Chengxi, Ouyang Xiaoping, Wang Xin, Zhu Junwu, Lu Jun
Key Laboratory for Soft Chemistry and Functional Materials of Ministry of Education, Nanjing University of Science and Technology, Nanjing, 210094, China.
Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL, 60439, USA.
Nat Commun. 2020 Feb 12;11(1):845. doi: 10.1038/s41467-020-14686-2.
Encapsulation strategies are widely used for alleviating dissolution and diffusion of polysulfides, but they experience nonrecoverable structural failure arising from the repetitive severe volume change during lithium-sulfur battery cycling. Here we report a methodology to construct an electrochemically recoverable protective layer of polysulfides using an electrolyte additive. The additive nitrogen-doped carbon dots maintain their "dissolved" status in the electrolyte at the full charge state, and some of them function as active sites for lithium sulfide growth at the full discharge state. When polysulfides are present amid the transition between sulfur and lithium sulfide, nitrogen-doped carbon dots become highly reactive with polysulfides to form a solid and recoverable polysulfide-encapsulating layer. This design skilfully avoids structural failure and efficiently suppresses polysulfide shuttling. The sulfur cathode delivers a high reversible capacity of 891 mAh g at 0.5 C with 99.5% coulombic efficiency and cycling stability up to 1000 cycles at 2 C.
封装策略被广泛用于缓解多硫化物的溶解和扩散，但在锂硫电池循环过程中，由于反复出现的严重体积变化，它们会经历不可恢复的结构失效。在此，我们报告一种使用电解质添加剂构建多硫化物电化学可恢复保护层的方法。添加剂氮掺杂碳点在全充电状态下在电解质中保持其“溶解”状态，其中一些在全放电状态下作为硫化锂生长的活性位点。当多硫化物存在于硫和硫化锂之间的转变过程中时，氮掺杂碳点与多硫化物发生高度反应，形成一个固体且可恢复的多硫化物封装层。这种设计巧妙地避免了结构失效，并有效抑制了多硫化物穿梭。该硫阴极在0.5 C下具有891 mAh g的高可逆容量，库仑效率为99.5%，在2 C下循环稳定性高达1000次循环。
