What Factors Affect the Service Life of Water Electrolysis Hydrogen Production Electrolyzers?

With the accelerated global energy transition, green hydrogen production has become a research hotspot, and water electrolysis hydrogen production technology has attracted extensive attention. As the core equipment for hydrogen production, the electrolyzer’s service life directly determines hydrogen production costs and project economic benefits. The factors affecting electrolyzer service life are complex; a single factor may induce multiple adverse conditions. Common restrictive components include inherent materials, operating conditions and electrodes. In addition, the electrolysis environment is also a key life-limiting factor, such as excessive voltage, over-high temperature and acidic/alkaline environments.

1. Start-Stop and Fluctuating Operating Conditions

What an electrolyzer fears most is not continuous operation, but frequent start-stop and power fluctuation.

Thermal Stress Cycling: The internal temperature of the electrolyzer changes repeatedly with each start and stop. Differences in the thermal expansion coefficients of various materials cause alternating stress on seals, pole plates and diaphragms, resulting in structural loosening, leakage and even rupture after long-term accumulation.

Reverse Current Corrosion: During shutdown, residual hydrogen and oxygen in the electrolyte diffuse mutually to form local galvanic cells on electrodes and generate reverse current, which severely corrodes the anodes.

Voltage Surge: Instant voltage overshoot during startup may break down the diaphragm, causing hydrogen-oxygen cross-permeation, bringing potential safety hazards and accelerating performance degradation.

2. Inherent Durability of Materials and Components

2.1 Diaphragm

Alkaline Water Electrolyzer: Asbestos diaphragms in the early stage have been phased out, and the mainstream products currently are polyphenylene sulfide (PPS) or polyether ether ketone (PEEK) composite diaphragms. Under high temperature and strong alkaline conditions, diaphragms will gradually become brittle with reduced porosity and increased internal resistance.

PEM Electrolyzer: Perfluorosulfonic acid membranes suffer from dual degradation including chemical degradation (free radical attack) and mechanical degradation (dry-wet cycling), leading to membrane thinning and increased pinholes, which in turn raise hydrogen permeation rate and reduce operation efficiency.

2.2 Electrode

For nickel-based electrodes, long-term operation will cause shedding of active substances, thickening of oxide layers and reduction of specific surface area, further increasing overpotential and energy consumption.Reverse current and impurity ions (Fe³⁺, Cl⁻, etc.) will accelerate electrode corrosion and poisoning.

2.3 Pole Plate and Sealing Parts

Once pinholes appear on the coating of pole plates (nickel-plated carbon steel or pure nickel), the carbon steel substrate will corrode and rust, contaminating the electrolyte and increasing contact resistance.Long-term exposure to high temperature, lye and pressure cycling will cause deformation and softening of sealing gaskets, resulting in liquid leakage or gas cross-flow.

3. Operating Conditions and Water Quality Control

3.1 Temperature and Pressure

When the operating temperature exceeds the optimal range, the aging rate of diaphragms and materials increases exponentially with every 10 ℃ rise in temperature. Generally, the optimal operating temperature of alkaline electrolyzers is 80–90 ℃, while that of PEM electrolyzers is 60–70 ℃.Pressure fluctuation also causes fatigue damage to the overall sealing and structure of the electrolyzer.

3.2 Electrolyte Purity

Alkaline Water Electrolyzer: Impurities (Fe³⁺, Ca²⁺, Mg²⁺) in KOH solution will form hydroxide precipitates and deposit on diaphragms, blocking pores and increasing resistance.

PEM Electrolyzer: Extremely sensitive to metal ions. Ion exchange occurs when metal ions contact the ion exchange membrane, reducing proton conductivity and accelerating membrane degradation.

3.3 Current Density and Load Range

Long-term operation under excessive current density will lead to local hot spots, increased oxygen evolution overpotential and bubble blockage of mass transfer channels, accelerating the aging of electrodes and diaphragms.Operation under ultra-low load (less than 20% rated load) results in low gas output and higher risk of hydrogen-oxygen mutual diffusion, forming explosive mixed gas. Meanwhile, the risk of reverse corrosion under low current also rises significantly.

4. Deficiencies in Operation and Maintenance Strategies

1.Failure to replace electrolyte on schedule (alkaline electrolyzers are recommended for electrolyte replacement every 1 to 2 years). After long-term operation, trace corrosion products (iron, nickel ions, etc.) from electrodes and pipelines will enter the electrolyte, turning it yellow and turbid, increasing resistance and raising energy consumption.

2.Lack of monitoring on single-cell voltage consistency. Abnormal voltage rise of individual cells without timely treatment will generate local high temperature and impurities, which spread through electrolyte and structures and accelerate the aging of adjacent cell seals and corrosion of pole plates.

3.Absence of nitrogen purging or protective measures after shutdown. Residual lye absorbs moisture and crystallizes, resulting in equipment corrosion.

4.Neglect of maintenance for pure water and cooling water systems, causing impurities to enter the electrolyzer.

5. Conclusion

The service life and performance of electrolyzers are never determined by a single factor, but rely on comprehensive optimization of material science, operation strategies and maintenance systems. From controlling the optimal temperature and matching reasonable current density, to regular electrolyte replacement and early warning of abnormal single-cell voltage, every seemingly minor parameter is critical to the stable operation of electrolyzer equipment.

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