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Chemical and electrochemical alkali metal exchange (AME) techniques are powerful tools to synthesize and investigate active materials for secondary Li-, Na- and K- or mixed-ion batteries. AME can provide fundamental...

The development of advanced battery materials requires fundamental research studies, particularly in terms of electrochemical performance. Most investigations on novel materials for Li‐ or Na‐ion batteries are carried out in 2‐electrode half‐cells (2‐EHC) using Li‐ or Na‐metal as the negative electrode. Although such cells are easy to assemble and generally provide sufficient stability, scientists should be aware of any effects that may influence the measurements, and care should be taken when interpreting the corresponding results. The present work addresses specific effects that can affect the electrochemical response of measurements in 2‐EHC. Critical points to be considered for long‐term cycling tests and impedance analyses are discussed and illustrated with relevant examples. The different behavior of electrochemically deposited and pristine alkali metal electrodes is shown, deriving the corresponding impact on the characterization of the actual material of interest. We demonstrate possible impacts of anode‐cathode crosstalk effects on the evaluation of measurements in 2‐EHC and highlight challenges and pitfalls in the interpretation of measurements in 2‐EHC with respect to kinetic and thermodynamic properties and battery performance. These findings contribute to the understanding of the limitations of electrochemical characterization in 2‐EHCs and should be carefully considered by researchers when evaluating novel battery materials.

The continuing rise of electric mobility is driving demand for lithium‐ion batteries to unprecedented levels. To ensure efficient production of high quality, yet affordable battery cells, while making the best use of available raw materials and processes, reasonable quality assurance criteria are needed. A step of particular importance, affecting all downstream processes, lies in electrode manufacturing including mixing, coating, drying, and calendering. Several classes of defects which originate in these processes are well‐known and detectable using various methods. The crucial point, however, lies in the quantification of their electrochemical significance, i. e., in an evaluation, which defect types, sizes and concentrations can be tolerated without impacting cell performance. Herein, we review the still scarce literature on that topic. It is found that, although the impact of some defects is quite well understood, others almost completely lack an evaluation of their criticality. We finally make suggestions for further studies paving the way to deduce knowledge‐based quality assurance criteria for the large variety of coating defects occurring in lithium‐ion battery electrodes.

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