Sabatier Principle‐Guided Co‐Solvent Selection for Highly Reversible Aqueous Zinc Batteries

Organic co‐solvents can effectively stabilize Zn anodes in rechargeable aqueous batteries, yet their selection remains largely empirical. Here, a Sabatier principle‐analogous framework utilizing molecular polarity index (MPI) as a quantitative descriptor is proposed for rational electrolyte engineering. By investigating a series of C3 alcohol co‐solvents with tunable hydroxyl configurations, we reveal a volcano‐type relationship between MPI and electrochemical performance. Co‐solvents with intermediate MPI, exemplified by 1,3‐propanediol, reside at the apex of this volcano. This optimal polarity strikes a delicate balance between interfacial homogeneity and reaction kinetics, thereby promoting dendrite‐free deposition and suppressing side reactions. Consequently, the optimized electrolyte enables a symmetric battery to achieve a cumulative plating capacity of 5.2 A h cm −2 and a lifespan exceeding seven months. Furthermore, a high‐mass‐loading (∼30 mg cm −2 ) Zn//I 2 pouch cell (0.3 A h) maintains stable operation over 1200 cycles with a low‐capacity decay rate of 0.057‰ per cycle. More importantly, this framework successfully identifies 1,2,4‐butanetriol as a new highly efficient co‐solvent, demonstrating the robust predictive power of MPI descriptor. This work translates the Sabatier principle into a predictive tool for electrolyte formulation, establishing a generalizable framework for co‐solvent screening that accelerates the development of high‐performance Zn batteries for large‐scale energy storage.