Electrolysis

In view of the shortage of fossil energy resources and the ongoing climate change caused by man-made carbon dioxide emissions, the energy industry is facing a radical change. In view of “green” energy technologies, hydrogen will play a leading role as secondary energy carrier if a low-cost and climate-neutral hydrogen production from renewable energy sources like wind or solar power can be achieved. The alkaline electrolysis of water has the potential to fulfill both requirements. However, in the last years only marginal efforts have been made to enhance efficiency and power density of the electrolysis process.

Nanocrystalline Electrodes

The electrocatalytical activity of electrodes and thus the efficiency of the electrolysis process are positively influenced by nanocrystalline electrode surfaces. Such a nanocyrstallinity of metal surfaces can be achieved by certain surface treatments or deposition processes. At Fraunhofer IFAM Dresden, nanocrystalline metal alloys (Fe- and Ni-base), which are produced by melting metallurgical routes, are being developed and tested with regard to their applicability as electrode materials.

3D Electrodes

Porous materials offer the possibility to enlarge the active surface area of the electrode and to direct the gas-electrolyte flow. Both aspects depend on the pore structure. At Fraunhofer IFAM Dresden we are able to modify open-cellular metal foams or fleeces so that they form nanocrystalline surfaces which are electrocatalytically very active:

    pore size: 5 - 1200 µm
    porosity: 50 - 95 vol.%

 

 

Electrochemical and Structural Analysis

Fraunhofer IFAM Dresden is equipped with state-of-the-art analysis tools in order to investigate the electrochemical properties, the surface morphology and the structural properties of the electrode materials:

    Electrochemical analysis

    - Cyclic voltammetry (CV)
    - Electrochemical impedance spectroscopy (EIS)
    - Polarization methods

    Scanning electron microscopy (SEM)

    Scanning probe microscopy

    - Atomic force microscopy (AFM)
    - Scanning tunneling microscopy (STM)
    - Electrochemical STM (EC-STM) and scanning electrochemical potential mapping
      (SECPM) for in situ experiments in liquids

 

Lab-scale Electrolyzer

The electrode materials are tested under realistic operation conditions (80°C, 30 m% KOH) to demonstrate their applicability. Therefore, the electrodes are integrated into lab-scale electrolyzer cells. Due to the flexible design of the test system different electrode configurations and operation conditions can be realized:

    Single-cell design
    20°C ... 80°C
    atmospheric pressure
    5 Normliter-H₂ per hour