Fast Ion Transport Interphase Constructed by Hollow Mesoporous Na3V2(PO4)3 for Stable Zinc Anode

Abstract The main challenges in aqueous Zn metal batteries (AZMBs) are enhancing energy density and cycling life, which require low Zn deposition/stripping overpotential and a stable anode/electrolyte interface. Herein, a hollow mesoporous Na 3 V 2 (PO 4 ) 3 coated with carbon (HMNVP/C) is designed as the Zn anode protective layer (HMNVP/C@Zn). The zincophilic Na 3 V 2 (PO 4 ) 3 with numerous ion channels accelerates Zn 2+ desolvation, while the hollow mesoporous structure promotes rapid Zn 2+ migration through the artificial solid electrolyte interface (ASEI). Diffusion rate differences between the external wall and hollow core lead to Zn 2+ enrichment and flux homogenization at the anode interface. Consequently, the HMNVP/C@Zn symmetric cell achieves an ultralow overpotential of 13.0 mV at 1 mA cm −2 , with stable cycling for over 1200 h at 0.2 mA cm −2 and 0.2 mAh cm −2 without dendrite growth. Additionally, for the first time, the electrochemical process of the zinc anode is decomposed into seven steps, and determine the relaxation time range of Zn 2+ migration in ASEI by in situ electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) analysis. It is noted that the rapid Zn 2+ migration within the stable HMNVP/C layer significantly reduces the impedance of subsequent zinc crystal growth. This novel design and characterization technique offer valuable insights for preparing advanced ASEI in AZMBs.