In-situ electro-polymerization of l-tyrosine enables ultrafast, long cycle life for lithium metal battery

Abstract

The growth of dendrites in the lithium (Li) metal anode hinders the commercialization of lithium metal batteries (LMBs). Electrolyte additives have proved to be an effective way to solve the problem of dendrites and improve the coulombic efficiency. Herein, we propose a strategy of using l-tyrosine (l-Tyr) as an additive to protect the lithium metal anode in situ, where l-Tyr can be electropolymerized in situ to form an ordered array of nanosheets on the surface of the lithium metal anode to uniformly deposit lithium ions. At the same time, the addition of l-Tyr changed the structure of the solvent in the electrolyte, because the carboxyl group on l-Tyr make DME form hydrogen bonds easily. Besides, the reduction of free DME makes more TFSI− involved in the formation of the SEI film on the electrode surface, which increases the proportion of LiF in the SEI film. With 2 wt% l-Tyr, Li||Li symmetric cells superior cycle stability in ether electrolytes, Li|Cu cells y improved stability up to 200 cycles with an average CE of 93.1% in ether electrolytes and Li||Li4Ti5O12 (LTO) demonstrated an excellent cycling capabilitie with 119 mAh/g capacity retention by the 5000th cycle.