Design of a permselective interface for highly stable Zn electrodeposition

In aqueous electrolytes, the deterioration of Zn electrodes is mainly due to the electrolyte species (e.g., H2O, Zn2+, SO42−, etc.) involved side reactions happened at the Zn|electrolyte interface (ZEI). Here, we design a permselective polyelectrolyte (PPE) that is rich in hydrophobic ethylhexyl and anion-blocking sulfonate (–SO3−) groups for Zn electrodes. During Zn electrodeposition, the PPE coating serves as a “screener” to suppress the transportation of undesired electrolyte species (e.g., H2O and SO42−) while homogenizing the Zn-ion flux. The as-designed PPE significantly suppresses the side reactions and prolongs the cycling life of the Zn electrodes. Even with a PPE layer as thin as ∼ 220 nm, the protected Zn electrode delivers an exceptional stability of > 3400 h at an areal capacity of 2 mAh cm−2 and > 1200 h at a higher capacity of 10 mAh cm−2, superior to those of the control cells.