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Prussian blue analogues (PBAs) cathodes can host diverse monovalent and multivalent metal ions due to their tunable structure. However, their electrochemical performance suffers from poor cycle life associated with chemo‐mechanical instabilities. This study investigates the driving forces behind chemo‐mechanical instabilities in Ni‐ and Mn‐based PBAs cathodes for K‐ion batteries by combining electrochemical analysis, digital image correlation, and spectroscopy techniques. Capacity retention in Ni‐based PBA is 96% whereas it is 91.5% for Mn‐based PBA after 100 cycles at C/5 rate. During charge, the potassium nickel hexacyanoferrate (KNHCF) electrode experiences a positive strain generation whereas the potassium manganese hexacyanoferrate (KMHCF) electrode undergoes initially positive strain generation followed by a reduction in strains at a higher state of charge. Overall, both cathodes undergo similar reversible electrochemical strains in each charge–discharge cycle. There is ~0.80% irreversible strain generation in both cathodes after 5 cycles. XPS studies indicated richer organic layer compounds in the cathode‐electrolyte interface (CEI) layer formed on KMHCF cathodes compared to the KNHCF ones. Faster capacity fades in Mn‐based PBA, compared to Ni‐based ones, is attributed to the formation of richer organic compounds in CEI layers, rather than mechanical deformations. Understanding the driving forces behind instabilities provides a guideline to develop material‐based strategies for better electrochemical performance. [ABSTRACT FROM AUTHOR]

The formation of dendrites is the bottleneck to harvest the high theoretical capacities of metal anodes. In this study, we investigated the impact of the solid‐electrolyte interface (SEI) layer on the electroplating of zinc metals in organic and aqueous electrolytes by using electrochemical techniques coupled with SEM, FTIR, and XPS. First, the electrochemical response of Zn plating in organic or aqueous electrolytes was compared with the ones for Li and Na metal plating by using analogous perchlorate salt dissolved in the same organic solvent. Under similar charge conditions, the cycle life of the metal electrodes was longer in the order of Zn (aqueous)>Li>Zn (organic)>Na. In organic electrolytes, the cycle life of the PAO‐Zinc is almost three‐fold longer than the as‐received zinc electrodes. The methodology established here can be used to study the impact of electrolyte salt and additives on the formation of dendrites on metal electrodes. [ABSTRACT FROM AUTHOR]

Keywords: dendrites; solid-electrolyte interface; metal batteries; interfacial kinetics; zinc EN dendrites solid-electrolyte interface metal batteries interfacial kinetics zinc 1 1 1 02/28/22 20220224 NES 220224 B The Cover Feature b illustrates that PAE-Zinc anodes (represented by the runner on the right) have better electrochemical stability and significantly longer cycle life compared to zinc anodes (represented by the runner on the left) when cycled in organic electrolytes. Cover Feature: Impact of the Solid-Electrolyte Interface on Dendrite Formation: A Case Study Based on Zinc Metal Electrodes (ChemElectroChem 4/2022) Dendrites, solid-electrolyte interface, metal batteries, interfacial kinetics, zinc. [Extracted from the article]