Mechanistic insights and emerging electrolytes for high-performance zinc metal batteries: Opportunities and challenges

Zinc-based rechargeable batteries have emerged as promising sustainable alternatives to lithium-ion systems due to their natural abundance, low cost, inherent safety, and high theoretical capacity. Despite these advantages, the practical deployment of Zn batteries is severely constrained by challenges associated with the Zn anode such as Zn-dendrites, passivation, hydrogen evolution reactions (HER), and self-corrosion in conventional aqueous electrolytes. Recent progress in non-aqueous and hybrid organic–aqueous electrolytes offer potential pathways to overcome these barriers. Nonaqueous systems expand the electrochemical stability window (ESW), suppress HER, and enable dendrite-free Zn deposition. Hybrid electrolytes, by partially disrupting water's hydrogen-bond network, effectively balance ionic conductivity with anode stability. Among these, organic phosphate solvents-such as trimethyl phosphate (TMP) and triethyl phosphate (TEP) stand out for their excellent salt solubility, broad liquid range, non-flammability, and strong anodic compatibility. This review summarizes the key challenges of Zn anode, recent advances in electrolyte engineering, mechanisms involved in cathode materials, discussing mechanistic insights, emerging materials, and future research directions especially focusing on the emergence of safe organic phosphate electrolytes and hybrid electrolytes. Emphasis is placed on the development of safe, scalable, and high-performance electrolytes as the cornerstone for next-generation Zn-based energy storage technologies.