Conversion-type anode chemistry with interfacial compatibility toward Ah-level near-neutral high-voltage zinc ion batteries

ABSTRACT High-voltage aqueous zinc ion batteries (AZIBs) with a high-safety near-neutral electrolyte is of great significance for practical sustainable application; however, they suffer from anode and electrode/electrolyte interfacial incompatibility. Herein, a conversion-type anode chemistry with a low anodic potential, which is guided by the Gibbs free energy change of conversion reaction, was designed for high-voltage near-neutral AZIBs. A reversible conversion reaction between ZnC2O4·2H2O particles and three-dimensional Zn metal networks well-matched in CH3COOLi-based electrolyte was revealed. This mechanism can be universally validated in the battery systems with sodium or iodine ions. More importantly, a cathodic crowded micellar electrolyte with a water confinement effect was proposed in which lies the core for the stability and reversibility of the cathode under an operating platform voltage beyond 2.0 V, obtaining a capacity retention of 95% after 100 cycles. Remarkably, the scientific and technological challenges from the coin cell to Ah-scale battery, sluggish kinetics of the solid-solid electrode reaction, capacity excitation under high loading of active material, and preparation complexities associated with large-area quasi-solid electrolytes, were explored, successfully achieving an 88% capacity retention under high loading of more than 20 mg cm−2 and particularly a practical 1.1 Ah-level pouch cell. This work provides a path for designing low-cost, eco-friendly and high-voltage aqueous batteries.