A practical 4.8-V Li||LiCoO <sub>2</sub> battery
Qi Xiong, Dedi Li, Shimei Li, Dechao Zhang, Ruhong Li, Shuo‐Qing Zhang, Shixun Wang, Hu Hong, Daming Zhu, Qi Liu, Xiulin Fan, Chunyi Zhi
Abstract
Raising the charging voltage of a lithium||lithium cobalt oxide (Li||LiCoO 2 ) battery is a shortcut to realize high energy density in portable electronics, while the fragile interface of highly delithiated LiCoO 2 (>4.55 volts) can trigger the lattice oxygen release, thus leading to severe interfacial degradation and structural collapse. Here, using lithium pentadecafluorooctanoate as a fluorine source to build robust lithium fluoride–rich electrode-electrolyte interfaces, stable Li||LiCoO 2 batteries at high voltage have been realized, capable of cycling 1500, 600, and 188 times at 4.6, 4.7, and 4.8 volts, respectively. Furthermore, the practicality of Li||LiCoO 2 batteries at an unprecedented cutoff voltage of 4.8 volts has been validated by a 2.7–ampere hour pouch cell, which shows a superior energy density of 544 watt-hours per kilogram and can operate more than 50 cycles. Our exploration of 4.8-volt LiCoO 2 may pave the way to ceaselessly approach its theoretical capacity.