Kinetic insights for high-rate and low-temperature ammonium-ion batteries/supercapacitors

Ammonium ion batteries/supercapacitors (AIBs/AISCs) have the metal dendrite-free, corrosion-free, and low-cost advantages, attracting growing attention recently. Besides, NH₄⁺has a flexible tetrahedral configuration and relies on hydrogen bonds to migrate and transfer charges, which are totally different from the rigid spherical metal ions and metallic coordination interactions; thus, AIBs/AISCs are superior in rate performance. Based on these advantages, AIBs/AISCs show great potential in the fields that require high power, safety, and cost effectiveness (e.g., new-energy vehicles, integrated energy storage systems, and altitude flight vehicles). Still, rate capabilities and low-temperature performance need to be improved before they can make major effects in applications. Given this unique kinetic behaviour, a systematic review of recent advancements in AIBs/AISCs is essential. This review highlights the progress of cathodes, anodes, and electrolytes according to the material classification. Their kinetic behaviors, NH₄⁺ transport mechanisms, reported strategies to enhance kinetics and low-temperature tolerance, and unsolved issues are all summarized. Some novel device configuration designs beneficial to rate performance are also demonstrated, e.g., dual-ion, ammonium-O₂, ammonium-metal cells, etc. Through this review, specific characteristics of every type of major materials are clear to see, as well as innovative designs at the device level, so researchers can conduct targeted investigations. We hope to stimulate the research on high-rate low-temperature AIBs/AISDs, and eventually promote their practical applications.