Elucidating the Role of Porous Zn Anode in Improving Zn Nucleation and Growth Behavior for Aqueous Zn-Ion Batteries

Achieving uniform deposition of metallic Zn and maintaining interfacial chemical stability are critical to addressing the dual challenges of dendrite formation and severe side reactions in aqueous Zn-ion batteries (AZIBs). Porous structure has been shown to mitigate these issues, but the relationship between dynamic deposition behavior of Zn and electrochemical performance in porous Zn anodes remains poorly understood. Herein, a selective phase etching strategy was employed to fabricate self-supporting porous Zn anodes (P-Zn_x, x = 20, 40, 55 and 70) with a three-dimensional bicontinuous ligament/pore structure. Through multiple in situ techniques (X-ray diffraction, impedance spectroscopy and optical microscopy) with finite element simulation, we investigated the dynamic nucleation and growth behavior of metallic Zn on the porous Zn anode. As benchmarked with a planar Zn free of pores, the optimized P-Zn₄₀ anode with abundant nucleation sites and strong (101) preferred orientation shows lower nucleation overpotential and uniform Zn plating without dendrite formation. Furthermore, the P-Zn₄₀ anode delivers excellent cycling stability for 1000 h at 0.5 mA cm^-2 in symmetric cells. More importantly, coupled the P-Zn₄₀ anode with a NH₄⁺-intercalated V₂O₅ cathode, the full cell displays superior cycling performance (1000 cycles with capacity retention of 85.9%) and rate capability, with negligible H₂ evolution as revealed by online differential electrochemical mass spectrometry. These findings provide valuable insights into the design of high-performance anodes for AZIBs.