Hierarchical heterostructure engineering of eutectic alloy for dendrite-free and ultralong-lifespan anode in low-temperature aqueous zinc-metal battery

Rechargeable aqueous zinc-metal batteries show genuine potential in grid-scale energy storage because of the inherent safety, low cost and high volumetric capacity. However, metallic Zn anode persistently undergoing uncontrollable dendrite growth and parasitic side reactions in subambient environments essentially impedes their practical application. Here we report hierarchically heterostructured ternary eutectic Zn-Ge-Cu alloy composed of interconnective Ge and ZnCu alloy lamellas (E-Ge/ZnCu) as a dendrite-free and ultralong-lifespan anode for low-temperature aqueous zinc-metal batteries. In such unique heterostructure with periodically local galvanic couples of Ge||ZnCu, the symbiotic Ge lamellas not only promote Zn stripping from ZnCu alloy to in-situ form porous intermetallic Zn 5 Cu, but also guide Zn plating along abundant nucleation sites of highly zincophilic Zn 5 Cu skeleton. Consequently, the E-Ge/ZnCu alloy electrode exhibits highly reversible Zn stripping/plating behaviors in aqueous hybrid electrolyte of triethylene glycol and zinc trifluoromethanesulfonate at temperatures from 25°C to −30°C, with ultralow voltage polarizations at various current densities and ultralong lifespan of > 6000 h with the cumulative areal capacity of > 6000 mAh cm −2 . This is also convincing in low-temperature E-Ge/ZnCu||Zn x V 2 O 5 /C full cells, which exhibit high capacities and excellent stability for > 5000 cycles at 25°C and −30°C.