Polymer-based lithium metal batteries are among the most promising next-generation systems owing to their high specific energy and operational safety. Despite significant progress in this battery field in recent years, relevant key challenges remain to be solved. Inhomogeneous and irreversible lithium metal deposition as well as volume expansion upon cell operation result in continuous interfacial changes and increased resistances. A solution for better reversibility of lithium inventory and enhanced overall cell performance comprise polymer-based artificial coatings, likely owing to favorable properties, such as sufficient ionic conductivity and high mechanical flexibility. The latter allows to counteract volume expansions upon cell operation while mitigating occurrence of high surface area Lithium metal deposits. Also, targeted design of artificial coatings may homogenize Li deposition and dissolution, in this way enhancing long-term performance of the cells.

The present study focuses on the monitoring of reactions among solid polymer electrolytes and artificial polymer coatings to address major challenges for operation of lithium metal batteries. Different concepts for the design of artificial coatings on lithium metal were critically evaluated invoking electrochemical impedance spectroscopy and galvanostatic experiments. Notably, observation of overpotential evolution and frequency-dependent interfacial processes provides further insights into critical processes such as charge-transfer and solid electrolyte interface (SEI) formation, thereby eventually providing pathways for tailored designs of artificial coatings facilitating long-term performance of the cells and reduced irreversible loss of lithium inventory in optimized next-generation lithium metal batteries.