How is anodizing applied in the new energy field?

Applications of Anodizing Processing in the New Energy Field

I. Overview of Anodizing Technology

Anodizing is a surface treatment technology that forms an oxide film on a metal surface through electrochemical methods. It is mainly applied to light metals such as aluminum, magnesium, and titanium, and their alloys. This process involves applying direct current to an electrolyte, causing an oxidation reaction on the metal surface to form a dense, uniform oxide film. This oxide film not only significantly improves the metal's corrosion resistance and wear resistance but also enhances its surface aesthetics and insulation properties.

The anodizing process mainly includes four steps: pretreatment, anodizing, coloring, and sealing. Pretreatment removes surface contaminants through degreasing, alkaline washing, and acid washing. The anodizing stage involves applying voltage in a specific electrolyte (such as sulfuric acid or oxalic acid) to form the oxide film. Coloring can be achieved through electrolytic coloring or dye adsorption. Hot water or steam is used to seal the micropores of the oxide film, improving its performance stability.

II. Special Requirements for Material Performance in the New Energy Field

The new energy industry includes multiple branches such as solar energy, wind energy, energy storage batteries, and hydrogen energy. These fields place special demands on material performance. First, new energy equipment often needs to operate in harsh environments for extended periods, such as the high salt spray environment of offshore wind power and the outdoor exposure of photovoltaic modules. Therefore, materials must possess excellent corrosion resistance. Second, new energy equipment prioritizes lightweight design to improve energy efficiency and reduce transportation and installation costs, making lightweight metal materials essential. Furthermore, certain applications require materials with good thermal conductivity, electrical insulation, or specific surface optical properties.

Anodizing treatment precisely meets these requirements: the oxide film significantly improves the corrosion resistance of lightweight metals; the weight increase after treatment is minimal; different colors and surface properties can be obtained through process adjustments; and the alumina film itself has excellent insulation properties. These characteristics make anodizing an important surface treatment technology in the new energy field.

III. Application of Anodizing in the Photovoltaic Industry

In the solar photovoltaic field, anodizing technology is mainly applied to aluminum alloy frames and support systems. Photovoltaic modules need to withstand outdoor environmental testing for more than 25 years, and traditional coating methods are insufficient to meet long-term weather resistance requirements. The alumina film formed on the surface of the anodized aluminum alloy frame is metallurgically bonded to the base metal, preventing coating peeling, exhibiting excellent UV resistance, and maintaining stable appearance and performance over a long period. Of particular note is that by adjusting the anodizing process parameters, surfaces with specific optical properties can be obtained. For example, the microporous surface formed by hard anodizing can reduce light reflectivity, which, when applied to photovoltaic frames, can reduce light pollution and improve the overall efficiency of the module. Furthermore, certain specially formulated electrolytes can produce dark oxide films, meeting the aesthetic requirements of building-integrated photovoltaics (BIPV).

Anodizing is also widely used in photovoltaic tracking bracket systems. These brackets require frequent rotation and long-term outdoor exposure, demanding extremely high wear and corrosion resistance. The thick oxide film (up to 50-100 micrometers) formed by hard anodizing can achieve a surface hardness of HV800 or higher, exhibiting excellent wear resistance while maintaining good corrosion resistance, significantly extending the service life of the bracket system.

IV. Application of Anodizing in Energy Storage Systems

Energy storage battery systems are an important component of the new energy field, and thermal management is a key factor affecting battery performance and safety. Anodized aluminum plates, due to their excellent thermal conductivity and insulation, have become an ideal material for battery heat dissipation systems. Anodized aluminum heat sinks not only possess excellent thermal conductivity, but their surface oxide film also provides electrical insulation, preventing short-circuit risks in the battery pack.

Regarding battery casings, anodizing offers multiple advantages: the oxide film prevents corrosion caused by electrolyte leakage; the sealing process reduces the surface friction coefficient, facilitating battery pack installation and maintenance; and specific surface colors can be used for identification and classification of different modules within the battery system. For large-scale energy storage power stations, these characteristics significantly improve system safety and maintainability.

Furthermore, the application of anodized aluminum is being explored in emerging solid-state battery technologies. Porous anodized aluminum templates can serve as solid electrolyte carriers or electrode structural frameworks; their regular nanopore structure facilitates ion transport while also exhibiting good thermal stability and mechanical strength.

V. Application of Anodizing in Hydrogen Energy Equipment

In the hydrogen energy industry chain, water electrolysis hydrogen production equipment and fuel cell systems face severe corrosive environmental challenges. Bipolar plates in proton exchange membrane electrolyzers (PEMECs) need to simultaneously possess good conductivity, corrosion resistance, and low cost. Titanium is chosen as a material due to its excellent properties, and anodizing further enhances its corrosion resistance and forms a stable passivation film.

Of particular note is the formation of an oxide film with specific catalytic activity on the titanium surface through micro-arc oxidation (a high-pressure variant of anodizing). This modified surface reduces the hydrogen/oxygen evolution overpotential and improves electrolysis efficiency. Simultaneously, the titanium oxide film exhibits photocatalytic properties, showing application potential in photoelectrochemical water splitting for hydrogen production.

Metal bipolar plates in fuel cell systems also benefit from anodizing technology. Traditional graphite bipolar plates are costly and have poor mechanical properties. After anodizing, the dense oxide film formed on the surface of metal bipolar plates significantly improves corrosion resistance in acidic environments while maintaining sufficient conductivity, making it an ideal alternative.

VI. Application of Anodizing in Wind Power Equipment

Anodizing technology is also used in various components of wind turbine generators. The aluminum alloy cable trays inside the wind turbine tower, after anodizing, not only have improved corrosion resistance, but the insulating properties of the oxide film also provide additional electrical safety. Offshore wind power environments are harsher, with high salt spray causing more severe corrosion to metal components. Thick-film hard anodizing of aluminum-magnesium alloy components can significantly extend maintenance intervals.

Anodizing is also commonly used for metal connectors and fasteners in wind turbine blades. These components withstand complex alternating stresses, requiring surface treatment that prevents corrosion while avoiding hydrogen embrittlement. Compared to traditional electroplating, anodizing does not introduce hydrogen atoms and provides sufficient surface hardness and wear resistance, making it a safer and more reliable option.

It is worth noting that rare-earth permanent magnets widely used in wind power equipment can also have their corrosion resistance improved through similar anodizing surface treatments. By using specific electrolyte formulations and process parameters, a uniform protective layer can be formed on the surface of NdFeB magnets, preventing magnetic performance degradation caused by oxidation and corrosion.

VII. Technological Challenges and Development Trends

Although anodizing is widely used in the new energy field, it still faces some technological challenges. The first is the environmental impact of the process; traditional anodizing uses large amounts of strong acids and alkalis, resulting in high wastewater treatment costs. Developing low-concentration, chromium-free, and nickel-free environmentally friendly electrolytes has become an important research direction. Secondly, energy consumption is a significant issue, especially since hard anodizing requires high voltages. Reducing process energy consumption is closely related to the sustainable development concept of the new energy industry.

Future development trends include: precise control of nanostructured anodized films to obtain specific functional surfaces; composite anodizing technologies, such as combining anodizing with sol-gel and electrophoretic deposition techniques to obtain multifunctional composite coatings; and intelligent anodizing production lines that utilize IoT technology for real-time monitoring and optimization of process parameters.

Of particular note is the synergistic innovation between anodizing technology and new energy materials. For example, nanostructures constructed on aluminum surfaces through anodizing can serve as anode materials for lithium-ion batteries; porous anodized aluminum templates can be used to prepare novel solar heat-absorbing coatings; and gradient anodized films may solve the thermo-mechanical stress matching problem. These innovative applications will further expand the value of anodizing in the new energy field.

VIII. Conclusion

Anodizing, as a mature surface treatment technology, demonstrates broad application prospects and continuous innovation vitality in the new energy field. From photovoltaic modules to energy storage systems, from hydrogen energy equipment to wind power equipment, anodizing provides a reliable surface solution for new energy equipment by improving the corrosion resistance, wear resistance, insulation, and aesthetics of light metal materials. With the rapid development of new energy technologies and increasingly stringent environmental requirements, anodizing technology will continue to innovate, providing more efficient, environmentally friendly, and multifunctional surface treatment solutions for the new energy industry, becoming one of the important technologies supporting the sustainable development of new energy.