Tailoring the Stability and Kinetics of Zn Anodes through Trace Organic Polymer Additives in Dilute Aqueous Electrolyte

High electrochemical stability and reaction kinetics of Zn anodes are crucial for rechargeable aqueous zinc batteries. Developing low-cost aqueous electrolytes is highly required. In this work, the fundamental principles to improve Zn anodes are systematically revealed in low-cost 1 M ZnSO4-based aqueous electrolytes using trace polymer additives with different polarities. The functional polymer additive could rearrange the "Zn2+–H2O–SO42––polymer" bonding network accordingly and reconstruct the space charge region of Zn anodes, resulting in distinctive cycling stability and reaction kinetics. Polymers with moderate polarity, such as polyacrylamide, exhibit synergic enhancement as the "smoother" and "thruster" for Zn2+ toward Zn anodes, with which Zn anodes run over 1300 h with Coulombic efficiency >99.65% under 2 mA cm–2, 2 mAh cm–2, showing uniform Zn deposition with minimal impact on reaction kinetics. This work provides useful insights on designing low-cost and high-performance aqueous electrolytes through functional electrolyte additives.