Solvation substitution of natural hydrophilic additive for highly stable zinc anode in aqueous zinc-ion batteries

Abstract

In this work, the bio-surfactant L-rhamnose (Rha) was added into the zinc sulfate electrolytes in aqueous zinc batteries (aZIBs) to enhance the stability of zinc anode undergoing long cycle plating/peeling process. The introduction of hydrophilic Rha can disrupt the hydrogen bonding network and restrict the activity of water in the electrolytes, leading to a decrease in hydrogen evolution potential from − 0.149 to − 0.183 V. Meanwhile, the solvation of Rha formed by replacing original Zn(H₂O)₆²⁺ structure can be more effectively absorbed onto zinc anode, promoting the uniform deposition of zinc ions. Under the action of Rha, the cycle life of Zn||Zn cells exceeds 1800 h, and that the Zn||Cu cells have a stable cycle of 841 times with average coulombic efficiency of 99.4979% at 1 mA cm⁻² and 1 mAh cm⁻². Additionally, the Zn||MnO₂ full cells maintained 350 cycles and theoretical capacity of 88.4% at 0.5 C.