Anion-functionalized interfacial layer for stable Zn metal anodes

Zinc metal anodes suffer from severe dendrite growth and parasitic hydrogen evolution in aqueous electrolyte, which impede their practical application. Herein, a negatively charged protection layer combining metal-organic framework (UIO-66-SO3H) and flexible sulfonated poly (ether ether ketone) (SPEEK) binder is introduced on the Zn anode to suppress dendrites and side reactions (denoted as USL-Zn). The USL film with zincophilic -SO3- functional groups uniformizes the Zn2+ flux and guides even Zn deposition. In addition, this protective layer functions as a physical barrier and manipulates the local electrolyte structure to mitigate the hydrogen evolution reaction and passivation on Zn anode surface. As a result, USL-Zn electrodes deliver high cycling stability at various current densities and capacities (700 h at 5 mA cm(-2), 5 mAh cm(-2) and 300 h at 10 mA cm(-2), 10 mAh cm-2), and enable high average Coulombic efficiency of 99.34 % (1 mA cm-2 for 1 h). Moreover, enhanced rate capacity and prolonged lifespan can be attained in Zn//VO2 full cells. This proposed strategy provides insight into the design of SEI layers in aqueous batteries and promotes the potential application of Zn metal batteries.

Automated summary

The introduction of a negatively charged protection layer on the zinc anode improves cycle stability and Coulombic efficiency by suppressing dendrite growth and hydrogen evolution. The protective layer also acts as a physical barrier and manipulates the local electrolyte structure to mitigate passivation on the anode surface.