Lithium (Li) metal batteries have been regarded as the most promising candidate for next generation energy storage because Li metal as anode has extremely high theoretical specific capacity (3860 mAh g^-1), the lowest negative electrochemical potential (-3.040 V vs. the standard hydrogen electrode) and low density (0.534 g cm^-3). However, the safety concerns and the short cycle life due to Li dendrite growth and low Coulombic efficiency (CE) hinder the development and practical applications of rechargeable Li metal batteries. During the past four decades, several approaches have been reported to suppress the Li dendrite growth and improve the stability of Li metal anode, including using Li alloys, solid-state electrolytes, polymer electrolytes, ionic liquids, highly concentrated liquid electrolytes, additives, protecting layers, interlayers between Li and separator, nanoscale design, selective deposition, Li-reduced graphene oxide composites, and so on. However, the improvement on Li anode as far is still unsatisfactory. In the past six years, we at PNNL systematically investigated various strategies to suppress Li dendrite growth, increase Li CE and enhance Li structural stability through electrolyte formulations, separator modifications, 3D structured Li hybrid anodes, and so on. In this talk, the electrolyte strategy to guide uniform growth and to form smooth deposition of Li metal film will be discussed and the details of the investigations will be reported at the presentation.

Acknowledgement

The research has been supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy (DOE) through the Advanced Battery Materials Research (BMR) Program.