3D Printing of Electron/Ion‐Flux Dual‐Gradient Anodes for Dendrite‐Free Zinc Batteries

Abstract 3D porous Zn‐metal anodes have aroused widespread interest for Zn‐ion batteries (ZIBs). Nevertheless, the notorious “top‐growth” dendrites caused by the intrinsic top‐concentrated ions and randomly distributed electrons may ultimately trigger a cell failure. Herein, an electron/ion‐flux dual‐gradient 3D porous Zn anode is reported for dendrite‐free ZIBs by adopting 3D printing technology. The 3D‐printed Zn anode with layer‐by‐layer bottom‐up attenuating Ag nanoparticles (3DP‐BU@Zn) establishes dual‐gradient electron/ion fluxes, i.e., an internal bottom‐up gradient electron flux created by bottom‐rich conductive Ag nanoparticles, and a gradient ion flux resulting from zincophilic Ag nanoparticles which pump ions toward the bottom. Meanwhile, the 3D‐printing‐enabled hierarchical porous structure and continuously conducting network endow unimpeded electron transfer and ion diffusion among the electrode, dominating a bottom‐preferential Zn deposition behavior. As a result, the 3DP‐BU@Zn symmetrical cell affords highly reversible Zn plating/stripping with an extremely small voltage hysteresis of 17.7 mV and a superior lifespan over 630 h at 1 mA cm⁻² and 1 mAh cm⁻². Meanwhile, the 3DP‐BU@Zn//VO₂ full cell exhibits remarkable cyclic stability over 500 cycles. This unique dual‐gradient strategy sheds light on the roadmap for the next‐generation safe and durable Zn‐metal batteries.