Interfacial Issues and Modification of Solid Electrolyte Interphase for Li Metal Anode in Liquid and Solid Electrolytes

The high energy density required for the next generation of lithium batteries will likely be enabled by a shift toward lithium metal anode from the conventional intercalation-based anode such as graphite. However, several critical challenges for Li metal originate from its highly reactive nature and the hostless reaction of deposition and stripping impede the practical use of Li metal as an anode. The role of the solid electrolyte interphase (SEI) is very important for the Li metal anode where the SEI must protect the dynamically changing surface of the Li metal. Since the SEI-generating reaction mechanisms for the two different electrolyte systems, liquid and solid, are considerably different, the SEI layers formed between the Li metal and the electrolytes in the two electrolyte systems have substantially different properties, causing different interfacial issues. Inhibition of the interfacial problems requires different strategies to reinforce the SEI layer for each of the electrolyte systems. However, the differences in the two electrolyte systems have not been clearly compared in the prior literature. In this report, the interfacial issues for the two different electrolyte systems are compared and different strategies for SEI modification are provided to overcome the issues.

Automated summary

The next generation of lithium batteries requires high energy density, which can be achieved by shifting from conventional intercalation-based anode (such as graphite) to lithium metal anode. However, the highly reactive nature of Li metal and the hostless deposition and stripping reactions hinder its practical use as an anode. The solid electrolyte interphase (SEI) plays a vital role in protecting the Li metal surface, but the SEI layers formed in different electrolyte systems have distinct properties, leading to different interfacial issues. This report compares the interfacial issues and provides different strategies for SEI modification to overcome these challenges.