The high specific capacity of alkalic
metal (Li, Na, and K) anodes
has drawn widespread interest; however, the practical applications
of alkalic metal anodes have been hampered by dendrite growth and
interfacial instability, resulting in performance deterioration and
even safety issues. Here, we describe a simple method for building
tunable fluoride-based artificial solid-electrolyte interphase (SEI)
from the fluorination reaction of alkali metals with a mild organic
fluorinating reagent. Comprehensive characterization by advanced electron
microscopes shows that the LiF-based artificial SEI adopts a crystal–glass
structure, which enables efficient Li ion transport and improves structural
integrity against the volume changes that occur during Li plating/stripping.
Compared with bare Li anode, the ones with artificial SEI exhibit
decreased voltage hysteresis, enhanced rate capability, and prolonged
cycle life. This method is also applied to generate fluoride-based
artificial SEI on Na and K metal anodes that brings significant improvement
in battery performance.