A variety of batteries employing an alkaline zinc anode have been investigated and partially commercialized over the last decades. Of these, electrically rechargeable zinc–air batteries have been considered, since the mid 20th century, as a sustainable alternative for future green energy storage. Despite significant research efforts, it has so far not been possible to commercialize this battery on a large scale because of insufficient performance. The herein presented overview is not yet another review; on the basis of a total of 70 articles published during the last 20 years in lab-scale research, we assess the state-of-the-art performance of alkaline zinc anodes for application in zinc–air batteries. We define descriptors for the underlying analysis focusing on the practical relevance and reveal that the expectations for this battery type are unfortunately too high. Most importantly, the ultimate long-lasting alkaline zinc anode has yet to be identified; this is a challenging, but appealing task for interdisciplinary research.

Limited cycling stability of secondary cells with zinc anodes arises mainly from the high solubility of oxidized zinc species in the alkaline electrolyte resulting in electrode shape change and loss of active material during repeated discharge and charge. We propose and successfully employ a homogeneous coating with an anion-exchange ionomer (AEI) on model electrodes with electron-conductive host structures to confine the oxidized zinc species. Ideally, the confinement of oxidized zinc species reduces the shape change of the electrode and keeps the active material as close as possible at its place of origin. In this work, the confinement concept for the oxidized zinc species is elucidated by means of electrochemical studies and X-ray photoelectron spectroscopy: as intended, an interlayer of zinc oxide forms between the AEI and the surface of the zinc electrode. This interlayer implies that the hydroxide ions are able to pass and react as intended, whereas the migration of oxidized zinc species into the bulk electrolyte is hindered. The coating with an AEI yields a higher amount of restored zinc during electrodeposition in comparison to an uncoated zinc electrode-applying an AEI coating increases the achievable cycle number by up to six times. We investigate the morphology of the cycled electrodes and derive thereby the needs for further material classes that might be employed in the confinement concept. This approach demonstrates the benefit of ion-selective coatings, allowing for the permeation of hydroxide ions but not of oxidized zinc species, a concept which improves rechargeable batteries with zinc anodes, such as zinc-oxygen batteries.

This review aims to address the status of transition metal‐based cathode materials for Mg2+ and Ca2+‐based multivalent‐ion batteries on a critical standpoint, providing a comprehensive overview. Multivalent‐based ions battery (MIB) technologies are among the most promising post‐lithium electrochemical energy storage devices currently studied, but they still fall short in several aspects due to their early stage of research. In addition, difficult experimental conditions related to the electrolyte systems and the cathode materials require an additional quote of care when performing experiments. In this review, a global approach is undertaken, from an introduction to electrolytes to the studied insertion parameters that allow a fast (de)insertion of multivalent ions. Then, the currently studied structural classes of cathode materials and a critical comment on data reporting, which are among the focal points of the actual state‐of‐the‐art research, are thoroughly discussed.

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H2O2 is produced at the interface between a room-temperature ionic liquid with decamethylferrocene as an electron donor and an acidic aqueous solution. The electron donor can be regenerated electrochemically.