Directing the Preferred Crystal Orientation by a Cellulose Acetate/Graphene Oxide Composite Separator for Dendrite-Free Zn-Metal Anodes

The issue of degraded reversibility of zinc-metal anodes resulting from dendrite formation and surface-originated side reactions is still a fundamental challenge for high-performance zinc-ion batteries (ZIBs). Herein, a graphene oxide (GO) nanosheet-modified cellulose acetate (CA) separator is developed with an ultralow mass loading of 4 μg cm–2 by a simple and low-cost filtration method. The low lattice mismatch of GO with Zn metal and numerous hydrophilic O-containing groups of GO enable the uniform Zn nucleation and the following epitaxial electrodeposition along the (002) plane, leading to a dendrite-free surface. Significantly, the surface chemistry of GO is important as the hydrophilic O-containing groups act as the initial nuclei deposition sites, which would grow larger along the parallel direction in the subsequent process. This CA/GO composite separator elevates the symmetric cell lifespan to 500 h at a high current density of 10 mA cm–2 (1 mA h cm–2). Moreover, a smaller nucleation overpotential (89 mV at 1 mA cm–2) and excellent Coulombic efficiency (higher than 96%) can also be realized. Furthermore, such a separator engineering enables an improved cycling performance for hydrated VO2/CC||Zn batteries. This separator modification method provides a pathway for the development of high-performance ZIBs and expands their application in other metal-related energy devices suffering from irreversibility.