A long-life lithium-oxygen battery via a molecular quenching/mediating mechanism
Jinqiang Zhang, Yufei Zhao, Bing Sun, Yuan Xie, Anastasia Tkacheva, Feilong Qiu, Ping He, Haoshen Zhou, Kang Yan, Xin Guo, Shijian Wang, Andrew M. McDonagh, Zhangquan Peng, Jun Lü, Guoxiu Wang
Abstract
The advancement of lithium-oxygen (Li-O 2 ) batteries has been hindered by challenges including low discharge capacity, poor energy efficiency, severe parasitic reactions, etc. We report an Li-O 2 battery operated via a new quenching/mediating mechanism that relies on the direct chemical reactions between a versatile molecule and superoxide radical/Li 2 O 2 . The battery exhibits a 46-fold increase in discharge capacity, a low charge overpotential of 0.7 V, and an ultralong cycle life >1400 cycles. Featuring redox-active 2,2,6,6-tetramethyl-1-piperidinyloxy moieties bridged by a quenching-active perylene diimide backbone, the tailor-designed molecule acts as a redox mediator to catalyze discharge/charge reactions and serves as a reusable superoxide quencher to chemically react with superoxide species generated during battery operation. The all-in-one molecule can simultaneously tackle issues of parasitic reactions associated with superoxide radicals, singlet oxygen, high overpotentials, and lithium corrosion. The molecular design of multifunctional additives combining various capabilities opens a new avenue for developing high-performance Li-O 2 batteries.