Work

Interface‐Controlled Phase Transformation and Corrosion Performance of Nb/NbN Multilayer Coatings for Bipolar Plates

Year: 2026

Type: article

Abstract: ABSTRACT Proton exchange membrane water electrolysis (PEMWE) bipolar plates face a critical trade‐off between corrosion resistance and interfacial electrical conductivity. To address this, Nb/NbN multilayer coatings with systematically varied interface densities were deposited on TA1 substrates via magnetron sputtering. Increasing the multilayer level induces a transition from substrate‐influenced to interface‐controlled growth, triggering a crystallographic phase transformation from metastable hexagonal ε ‐NbN to stable cubic δ ‐NbN. Finite element analysis and physical characterizations confirm this transformation drives microstructural densification and a pronounced increase in compressive residual stress, accompanied by pronounced transformation‐associated residual‐stress evolution and microstructural densification. Consequently, transformation‐induced densification significantly enhances corrosion resistance in simulated PEMWE anodic environments, while electrical properties remain moderate alongside stress accumulation. Notably, the Nb/NbN‐3 coating architecture achieves an optimal balance, exhibiting low interfacial contact resistance (∼6.18 mΩ·cm 2 at 1.5 MPa) and high corrosion stability (0.195 µA·cm − 2 in potentiostatic polarization). Ultimately, these results establish interface‐density engineering as a highly effective strategy for optimizing the performance of bipolar plates in advanced PEMWE systems.

Source: Small

DOI: 10.1002/smll.76237

Authors: Zihui Xu, Jiawei Wan, Jian Lin, Mengying Wang, Xungang Diao

Institutions: Beihang University, Tianmushan Laboratory

Language: English

Topic: Fuel Cells and Related Materials

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

SDG: Affordable and clean energy

Open Access status: bronze

Funder: Beihang University