Coulombic Efficiency for Practical Zinc Metal Batteries: Critical Analysis and Perspectives

Reviewartikel, 2024

Climate change and energy depletion are common worries of this century. During the global clean energy transition, aqueous zinc metal batteries (AZMBs) are expected to meet societal needs due to their large-scale energy storage capability with earth-abundant, non-flammable, and economical chemistries. However, the poor reversibility of Zn poses a severe challenge to AZMB implementation. Coulombic efficiency (CE) is a quantitative index of electrode reversibility in rechargeable batteries but is not well understood in AZMBs. Thus, in this work, the state-of-art CE to present the status quo of AZMB development is summarized. A fictional 120 Wh kg-1 AZMB pouch cell is also proposed and evaluated revealing the improvement room and technical goal of AZMB chemistry. Despite some shared mechanisms between AZMBs and lithium metal batteries, misconceptions prevalent in AZMBs are clarified. Essentially, AZMB has its own niche in the market with unique merits and demerits. By incorporating academic and industrial insights, the development pathways of AZMB are suggested. This work comprehensively explores recent advancements in the Coulombic efficiency of aqueous zinc ion batteries, illuminating overlooked test details. Setting a target of 99.9% efficiency, the researchers propose a hypothetical 120 Wh kg-1 MnO2/Zn pouch cell and delineate a three-stage plan to enhance energy density in future developments. Additionally, this work provides valuable insights for improving Coulombic efficiency and refining battery testing methodologies.image