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

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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 Na3V2(PO4)3 coated with carbon (HMNVP/C) is designed as the Zn anode protective layer (HMNVP/C@Zn). The zincophilic Na3V2(PO4)3 with numerous ion channels accelerates Zn2+ desolvation, while the hollow mesoporous structure promotes rapid Zn2+ migration through the artificial solid electrolyte interface (ASEI). Diffusion rate differences between the external wall and hollow core lead to Zn2+ 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 Zn2+ migration in ASEI by in situ electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) analysis. It is noted that the rapid Zn2+ 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.
Funding Information
  • National Natural Science Foundation of China (NSFC 52432002, 52372041, 52302087)
  • China Postdoctoral Science Foundation (2023M740895)
  • Fundamental Research Funds for the Central Universities (HIT.OCEF.2021003)

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