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 SO 4 2- in the ZnSO 4 electrolyte and promote Zn 2+ migration. The modified layer can avoid the drastic growth of dendrite by reducing concentration gradients especially at high currents. In addition, the captured SO 4 2- may retard the aggregation of Zn 2+ 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 5mA cm -2 and 5000 cycles for 10mA cm -2 ). Meanwhile, the capacity retention rate of Zn@LDO/MnO 2 battery reaches 86% after 1600 cycles under 1A g -1 .

Keywords: High current, Zn ion battery, Concentration gradient