Rechargeable batteries with high energy density, long cycle life, and low cost are considered key enablers for sustainable consumer electronics, electric vehicles (EVs), and smart grid energy storage. Lithium-ion batteries (LIBs) have been emerged

Blended electrode materials containing high‐capacity silicon (Si) and robust graphite (Gr) materials are considered advanced alternatives to pure graphite electrodes used in Li‐ion batteries. Understanding the component‐specific lithiation and delithiation behavior and electrochemical interactions between the blended materials is of crucial importance for targeted optimization of composition and microstructural design, yet hardly addressed to date. Herein, a model‐like Si/Gr blended electrode and special electrochemical cell are introduced to directly capture the component specific behaviors for the first time. This includes studies of the formation cycles, the reaction distribution between Si and Gr, the component‐specific contributions to the capacity at different charge and discharge rates, and the internal dynamics during pulse loads and subsequent relaxation. The deconvolution of the components’ behavior during operation provides fundamental insights that contribute to a profound understanding and targeted optimization of Si/Gr blended electrodes. Furthermore, the application of the presented experimental approach can serve scientists to identify and study other advanced materials combinations as blended electrodes for rechargeable batteries.

Zero-excess Li metal batteries (ZELMB), in which the Li-metal anode is plated in situ on the anode current collector during initial charging, have received considerable attention in recent years. Such batteries hold enormous potential for increasing energy density and simplifying battery production, thus reducing costs, material, and energy requirements. However, transfer into application has so far been limited by challenges related to the non-uniform deposition behavior of lithium, which leads to inadequate performance and safety concerns. To meet these challenges, the electrochemical deposition behavior of lithium must be very well understood to derive and evaluate knowledge-based optimization approaches. For this purpose, advanced characterization methods are urgently needed. Herein the use of operando electrochemical dilatometry (OED) to study Li deposition and dissolution in ZELMB is demonstrated. We show how OED not only provides information on thickness changes during Li deposition and stripping, but also allows insights regarding morphology evolution and quantification of dead Li. The present work is intended to serve as an example to demonstrate the valuable insights that can be gained with OED and to encourage the scientific community to use it to support the development of advanced Li-, Na-, or K-metal batteries.

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.