Ten concerns of Zn metal anode for rechargeable aqueous zinc batteries

Summary

Thousands of articles have been reported to enhance the electrochemical stability/reversibility of the Zn-metal anode (ZMA). However, some scientific concepts, engineering factors, mechanism models, and characterization limitations are still not comprehensively understood. Here, based on fair experiments, we proposed ten critical concerns on ZMAs, including the following: (1) scientific concepts misunderstanding on basic electrochemistry and crystallography terms, (2) non-scientific engineering factors affecting Coulombic efficiency (CE) assessment based on operation modes and "edge effect," and cell parameters on regulating battery performance, (3) influence mechanisms of coating modifications and Zn₄(OH)₆SO₄·xH₂O (ZHS) byproduct, and (4) limitations of typically used characterization tools and accuracy of advanced in situ technique paradigms. We not only proposed existing dilemmas but also provided the right medicine for corresponding pains. This perspective hopes to awaken research status of blind advance on aqueous zinc batteries and provide constructive guidance for building theory models and designing modification strategies to meet the challenges of energy storage scientifically and effectively.