Electrochemical engineering in aqueous metal-ion batteries

Aqueous metal ion batteries (AMIBs), with merits of safety, ambient assembly, and eco-friendliness, demonstrate great potential in various energy storage scenarios. Despite the laboratory-scale progress in battery components and mechanisms featured by large specific capacities and long lifespans, AMIBs' practical use meets challenges with electrodes and electrolytes. It is crucial to prepare a review discussing the problems and solutions for the battery performance degradation during the electrode/battery scaleup from the perspectives of ion mass transfer and electrode reaction, which is proposed as the electrochemical engineering in AMIBs. We first introduce the anodic reactions and their effective reinforcement by molecule chemistry and electrodeposition. Then, we discuss the ion diffusion in electrolytes by learning from the Nernst-Planck theory, followed by the interphase ion diffusion at the electrolyte-cathode interface. After that, we highlight the lattice-void and particle-gap ion diffusion in cathodes and the cathodic reactions reinforced by catalysis and micro-reactor construction. Finally, we present the challenge and perspective of this blooming field toward the lab-to-market transition of AMIBs.