A reality check and tutorial on electrochemical characterization of battery cell materials: How to choose the appropriate cell setup

The ever-increasing demand for electrical energy storage technologies triggered by the demands for consumer electronics, stationary energy storage systems and especially the rapidly growing market of electro mobility boosts the need for cost-effective, highly efficient and highly performant rechargeable battery systems. After the successful implementation of lithium ion batteries (LIBs) in consumer electronics and electric vehicles, there is still a need for further improvements in terms of energy and power densities, safety, cost and lifetime. In the last decades, a large battery research community has evolved, developing all kinds of new battery materials, e.g., positive and negative electrode active materials for different cell chemistries, electrolytes, related auxiliary (inactive) materials and their constituents. Different battery cell setups, including so-called “half-cell”, “symmetrical-cell” and “full-cell” setups as well as two-electrode or three-electrode configurations, are described in the literature to be used in the laboratory for the electrochemical characterization of battery components like electrode materials and electrolytes. Typically, all cell setups display certain limitations or issues concerning their application for the parameter determination of battery materials. In this review article, we highlight the advantages but also the limitations of different cell setups, with special focus on two- and three-electrode configurations with or without the help of “auxiliary” excess capacity Li metal electrodes. We point out possible mistakes and/or misinterpretations and give the reader recommendations, i.e., a guide for the right choice of the cell setup/configuration appropriate for the intended aim of the electrochemical investigation.