Reducing Zn-ion concentration gradient by SO42−-immobilized interface coating for dendrite-free Zn anode

Abstract

The Zn metal anode is considered one of the most promising candidates for aqueous zinc ion batteries. However, Zn anode is seriously plagued by the issues of dendrite and side reactions. Herein, we constructed Layered Double Oxide (LDO) artificial interface protective coating which can attract SO42− in the ZnSO4 electrolyte and promote Zn2+ migration. The modified layer can avoid the drastic growth of dendrite by reducing concentration gradients especially at high currents. In addition, the captured SO42− may retard the aggregation of Zn2+ on the anode surface and promote uniform deposition of Zn. The assembled cells can achieve average coulombic efficiency of 99.7 % after 2800 cycles and superior cycling performance (6600 cycles for 5 mA cm−2 and 5000 cycles for 10 mA cm−2). Meanwhile, the capacity retention rate of Zn@LDO/MnO2 battery reaches 86 % after 1600 cycles under 1 A g−1.