Morphological and Chemical Mapping of Columnar Lithium Metal

The development of high energy density lithium metal batteries requires the successful implementation of thin lithium metal anodes with limited excess lithium. Primary electrodeposition is a strategy for on-site production of thin lithium metal and avoids the costs and challenges of traditional lithium metal foil processing and transport. Herein we explore the interfacial parameters governing deposition of up to 30 μm uniform columnar lithium in LiF-rich environments, by investigating the effects of both the substrate/lithium and electrolyte/lithium interfaces for three common electrolytes: carbonate, fluorinated carbonate, and ether-based. By analyzing the transition to growth heterogeneity at higher current densities and later stage deposition, we confirm that improved growth uniformity is coupled with increasingly stable solid electrolyte interphases, but that this correlation differs for the three electrolytes. In comparison with conventional dimethyl carbonate, fluorinated carbonate and ether-based electrolytes exhibit fewer chemical shifts in the morphological transition region. We pinpoint the chemical origins of growth transitions in conventional dimethyl carbonate and show that close-packed columnar growth can be electrodeposited in ether-based electrolyte at 100-fold higher current densities.