Lithium Metal Interface Modification for High-Energy Batteries: Approaches and Characterization

Rechargeable batteries have been a profoundly greater part of our lives than we could have ever imagined. The rechargeable Li-ion batteries (LIBs) that have been developed for transport systems even put fossil fuels in the corner. However, state-of-the-art Li-ion batteries with graphite anodes are now approaching their theoretical specific energy limits, so they cannot meet the increasing demands of a range of portable electronics and large-scale energy storage systems. Li metal is one of the most promising anode materials that could break through the energy density bottleneck of Li-ion batteries due to its ultrahigh specific capacity and very low potential compared to other anode materials. Nonetheless, the direct use of Li metal in commercial battery systems has been hindered due to significant obstacles associated with it such as safety issues, corrosion from chemical reactions that occur inside the battery, or poor cycling performance. The fundamental reason for these problems is the dendritic growth of Li-ions on the Li metal anode during cycling, as a result of the interfacial phenomena of Li metal and electrolytes. Modification of the Li metal interface with an electrolyte presents an efficient solution to solve these problems. In this review, the current challenges facing the development of Li metal anodes are presented in detail. The most recent advances in Li metal anodes using a controlled interface between the Li metal surface and an electrolyte are highlighted and an introduction on the synthesis and production methods for the application of high-energy-density battery systems such as Li-oxygen (Li-O-2), Li-sulfur (Li-S), and Li metal batteries with high-energy density cathodes is presented. Furthermore, the recent developments in the in situ/operando analysis tools adopted for the investigation of Li metal anodes such as the structural and chemical changes, dynamic properties, and solid-electrolyte interface (SEI) layer properties are described and summarized. Finally, some suggestions are given in the direction of the development of Li metal with artificial surface layers for use in future high-energy batteries.