Identifying Pitfalls in Lithium Metal Battery Characterization

Abstract Over the past decade, there has been a revival of research activity on lithium metal batteries (LMBs) as these could be a solution for key challenges of electromobility and the energy revolution. While there is growing consensus in the scientific community that common reporting standards and testing conditions for LMBs have to be established, a vast majority of research activities on lithium metal use lab‐dependant testing protocols. For that reason, this publication aims to shed light on various, potentially neglected aspects in battery assembly and testing. Firstly, the long‐term cycling, regarding a range of experimental parameters, such as current density, capacity, electrolyte type and its quantity, as well as contribution of the electrode edges, is shown in both symmetric (Li||Li) and asymmetric (Cu||Li) configurations. The second part focuses on the reversibility of lithium thickness during cycling with and without protected electrode edges, investigated by operando dilatometry. By bringing the insights from this parameter study together, we aim to contribute to better experiment design for future LMB studies, as well as a better understanding for the failure mechanism of Li metal anodes.