Published February 21, 2024 | Published
Journal Article

Dual role of hBN as an artificial solid–electrolyte interface layer for safe zinc metal anodes

Abstract

Highly reversible and stable cycling of zinc metal anodes remains a challenge due to the undesirable side reaction of the hydrogen evolution reaction (HER) and dendrite formation. Herein, hexagonal boron nitride (hBN) with large area and continuous growth was developed and used as the artificial solid–electrolyte interface (SEI) coating, which plays two roles to protect the electrode surface by (1) mitigating the side reactions and (2) inducing the epitaxial electrodeposition of hexagonal close-packed (hcp) Zn to form the compact Zn structure aligned in (002) orientation. From the density functional theory (DFT) calculations, hBN exhibits a remarkably small lattice mismatch (4.1%) with the Zn (002) surface. Additionally, insignificant Zn binding energy of hBN (−0.20 eV) reveals a weak interaction between hBN and Zn atoms; therefore fewer seeding points are provided for generating Zn dendrites. In addition, the low surface energy of the hBN interface enhances the electrolyte wettability to the electrode–electrolyte interface, promoting smooth Zn plating. Consistently, highly horizontally aligned Zn metal deposition without dendrites and H2 formation was visualized from an in situ optical cell. The symmetric cell shows stable cycling with a significantly smaller plating overpotential of 0.15 V over 300 cycles, while a full cell with an AlxVOH cathode exhibits highly stable cycling over 50 cycles with a 73.6% capacity retention rate and improved rate capability.

Copyright and License

© The Royal Society of Chemistry 2024.

Acknowledgement

The work described in this paper was partially supported by grants from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. HKUST C6008-20E and 16304421), Research Fund of Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology (2020B1212030010) and Shenzhen Special Fund for Central Guiding the Local Science and Technology Development (2021Szvup136). Technical assistance from the Advanced Engineering Materials Facilities and the Materials Characterization and Preparation Facilities at HKUST is greatly appreciated.

Data Availability

https://www.rsc.org/suppdata/d3/ta/d3ta06947h/d3ta06947h1.pdf

Conflict of Interest

The authors declare no conflict of financial interests.

Additional details

Created:
March 25, 2024
Modified:
March 25, 2024