A practical 4.8-V Li||LiCoO2 battery

Abstract

Raising the charging voltage of a lithium||lithium cobalt oxide (Li||LiCoO2) battery is a shortcut to realize high energy density in portable electronics, while the fragile interface of highly delithiated LiCoO2 (>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||LiCoO2 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||LiCoO2 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 LiCoO2 may pave the way to ceaselessly approach its theoretical capacity.