质子交换膜电解水(Proton Exchange Membrane Water Electrolysis，PEMWE)制氢技术具有响应速度快、氢气纯度高、电流密度大、适应波动性可再生能源等优点，是绿色制氢技术的重要发展方向。金属双极板作为PEM电解水电堆的重要组件，在运行过程中会发生氧化、腐蚀等反应，引起界面接触电阻的增加，从而缩短电堆寿命以及降低水电解效率。因此，在双极板表面制备低成本、高性能的防护涂层已成为PEM制氢技术的重要研究方向。在该技术背景下，概述了电解水制氢技术原理及现状，介绍了PEM制氢双极板材料及其特性，系统总结了PEM制氢双极板防护涂层的研究进展，包括金属、金属氮化物、导电氧化物、金属磷化物和非晶碳基涂层的制备方法、结构，及其在PEM电解水模拟工况下的耐腐蚀性能、接触电阻和应用验证等数据。从制备成本、腐蚀前后接触电阻变化、耐高电位腐蚀性能等方面阐述了不同涂层的主要优点和缺点，并对PEM制氢双极板涂层及其制备技术的发展趋势进行了展望，为今后PEM电解水制氢双极板涂层材料的设计开发和应用提供借鉴。

Proton exchange membrane water electrolysis (PEMWE) technology is regarded as a significant development direction for future green hydrogen production technology, which has advantages in rapid response, high hydrogen purity, high current density, and high compatibility with renewable energy sources, etc. As crucial components of PEM hydrogen production stacks, metal bipolar plates suffer from oxidation and corrosion during stack operation, which results in increased interface contact resistance (RIC), shortened stack‘s service life and reduced water electrolysis efficiency. At present, the lack of high-performance bipolar plates has become one of the key factors limiting the commercial application of PEM hydrogen production technology. As a result, developing low-cost, corrosion-resistant, and highly conductive protective coatings of bipolar plates has been a hot research topic in PEM hydrogen production technology. In this context, this paper outlines the basic principles and present situation of hydrogen production by water electrolysis technology. It introduces the main types, characteristics, and issues of PEM water electrolyzer bipolar plate materials. More importantly, this paper provides a comprehensive overview of the current research on protective coatings for bipolar plates used in PEM water electrolyzers, including their preparation methods, structural characteristics, anti-corrosion properties in simulated water electrolysis conditions, contact resistance, and experimental validation under PEM water electrolysis conditions. The types of coating materials are mainly metals, metal nitrides, conductive oxides, metal phosphides, and carbides. It indicates that a thin noble metal Pt coating offers an effective solution for the electrical conductivity and corrosion protection of titanium bipolar plates, yet it fails to protect stainless steel bipolar plates against corrosion. Highly corrosion-resistant metal coatings (Nb, Ti, etc.) with high thickness provide a feasible technical path for low-cost bipolar plates made of stainless steel or copper. Metal nitride coatings exhibit excellent electrical conductivity and thermal stability, but their corrosion resistance is inadequate in aggressive corrosive environments. Further improvement in the electrochemical stability of nitride coating is still needed to target electrolytic cell applications. Multiphase composite design may provide a promising technical path for this purpose. From a low-cost perspective, some conductive and corrosion-resistant materials (e.g. Ti4O7) provide new and possible solutions for protection of bipolar plates, which exhibit the similar water electrolysis performance to Pt coatings when applied to the surface of bipolar plates. However, a long-term verification test is currently lacking in the present study. The amorphous carbon-based coatings also attract strong interests in PEM water electrolyzers because of their low cost and high electrical conductivity. Notably, it just tends to be used for the cathode-side protection of bipolar plates due to intolerance to high potential. In addition, this review synthesizes critical performance data, specifically corrosion resistance and contact resistance, for representative coatings when tested under simulated PEM water electrolysis conditions. A comparative assessment of these coatings is conducted across parameters such as fabrication complexity, post/after corrosion contact resistance stability, and high-potential durability. Finally, the study outlines future trends in coating development and preparation technologies, providing actionable insights for the design, development, and industrial deployment of advanced bipolar plate coatings in PEM water electrolysis systems.