Mechanistic Study of Interfacial Modification for Stable Zn Anode Based on a Thin Separator

The interface plays a pivotal role in stabilizing metal anode. Extensive studies have been made but systematic research is lacking. In this study, preliminary studies are conducted to explore the prime conditions of interfacial modification to approach the practical requirements. Critical factors including reaction kinetics, transport rate, and modulus are identified to affect the Zn anode morphology significantly. The fundamental principle to enhance the Zn anode stability is systematically studied using the TEMPO-oxidized cellulose nanofiber (TOCNF) coating layer with thin a separator. Its advantageous mechanical properties buffer the huge volume variation. The existence of hydrophilic TOCNF in the Zn anode interface enhances the mass transfer process and alters the Zn²⁺ distribution with a record high double-layer capacitance (390 uF cm⁻²). With the synergetic effect, the modified Zn anode works stably under 5 mA cm⁻² with a thin nonwoven paper as the separator (thickness 113 µm). At an ultra-high current density of 10 mA cm⁻², this coated anode cycles for more than 300 h. This strategy shows an immense potential to drive the Zn anode forward toward practical applications.