Solid electrolyte interphases in lithium metal batteries

Lithium metal batteries (LMBs) are a promising alternative to lithium-ion batteries (LIBs) owing to the high theoretical specific capacity (3,860 mAh G^-1) and low electrode potential (-3.04V vs. standard hydrogen electrode) of lithium metal.  High-specific-energy LMBs would enable novel high-energy applications, such as electric flight, and facilitate the electrification necessary to meet net-zero targets.  The commercialisation of LMBs, however, is currently limited by their poor cycle life.

Reactions between the anode and electrolyte form a thin solid electrolyte interphase (SEI) layer that regulates lithium plating/stripping morphology and controls LMS cycling stability, which has been the focus of numerous research efforts.  In this perspective*, we highlight recent breakthroughs and common misconceptions in the literature and identify several key research fronts necessary for accurate SEI characterisation, with emphasis on its nanostructure, transport and mechanical properties.

*'Solid electrolyte interphases in lithium metal batteries' published in Joule.