  Rechargeable lithium, sodium, and aluminum metal-based batteries are among
the most versatile platform for high-energy, cost effective electrochemical
energy storage. Non-uniform metal deposition and dendrite formation on the
negative electrode during repeated cycles of charge and discharge are major
hurdles to commercialization of energy storage devices based on each of these
chemistries. A long held view is that unstable electrodeposition is a
consequence of inherent characteristics of these metals and their inability to
form uniform electrodeposits on surfaces with inevitable defects. We report on
electrodeposition of lithium in simple liquid electrolytes and in nanoporous
solids infused with liquid electrolytes. We find that simple liquid
electrolytes reinforced with halogenated salt blends exhibit stable long-term
cycling at room temperature, often with no signs of deposition instabilities
over hundreds of cycles of charge and discharge and thousands of operating
hours. We rationalize these observations with the help of surface energy data
for the electrolyte/lithium interface and impedance analysis of the interface
during different stages of cell operation. Our findings provide support for an
important recent theoretical prediction that the surface mobility of lithium is
significantly enhanced in the presence of lithium halide salts.
