Metal-organic frameworks with carboxyl functionalized channels as multifunctional ion-conductive interphase for highly reversible Zn anode

Aqueous zinc batteries are promising for large-scale energy storage. However, the cycle stability of the Zn anode is severely hindered by the continuous side reactions and uncontrollable dendrite growth. Here, a carboxyl functionalized metal-organic frameworks, UiO-66-(COOH)2, has been developed as a multifunctional ion-conductive interphase to stabilize the Zn anode. The strong interaction between the carboxyl groups within UiO-66-(COOH)2 and hydrated Zn2+ could construct a concentrated electrolyte in the channels, promote the diffusion of electrolyte, and facilitate the desolvation of hydrated Zn2+, thereby inhibiting the water-induced side reactions and dendrite growth. Consequently, the UiO-66-(COOH)2 coated Zn achieves a lifespan of over 2800 h in symmetric cell at 2 mA cm−2 and 2 mAh cm−2, much better than those of bare Zn (114 h) and UiO-66 coated Zn (810 h). Moreover, the full cell based on the UiO-66-(COOH)2 coated Zn anode and V2O5·nH2O cathode also exhibits a high capacity retention of 91% after 2400 cycles at 1 A g−1. This work provides new insights for the rational design of advanced ion-conductive interphase for metal anodes.