LO2CAL – Increasing the Lifetime of the Oxygen-Depolarized Cathode for Industrial Use in Chlor-Alkali Electrolysis

Chlor-alkali electrolysis is a key process in the chemical industry for the production of chlorine, hydrogen, and caustic soda. Accounting for approximately 2% of Germany’s total electricity consumption (as of 2018), it is among the most energy-intensive industrial processes.

A significant advancement in reducing electrical energy demand has been achieved through the use of so-called oxygen-depolarized cathodes (ODCs). These represent a specialized form of gas diffusion electrodes (GDEs) and enable the oxygen reduction reaction (ORR) instead of conventional hydrogen evolution. This alternative cathodic process allows for a significant reduction in cell voltage, resulting in energy savings of up to 25% compared to conventional chlor-alkali technologies.

Initial industrial applications of the ODC process have demonstrated great potential, but also revealed certain challenges. In particular, process-related shutdowns lead to accelerated electrode degradation, thereby limiting system lifetime.

The joint project LO2CAL aims to significantly extend the service life of ODC systems under real operating conditions, thereby unlocking further energy savings. The focus lies on optimizing the electrode structure and catalyst—especially with regard to pore structure, surface properties, and catalyst doping.

The scope of work at TU Clausthal includes the process-integrated adaptation of the manufacturing method for gas diffusion electrodes, along with their comprehensive characterization regarding structure, surface morphology, and electrochemical performance. Further core focus areas are the development of accelerated aging tests and the establishment of a dynamic model to describe degradation processes under realistic operating conditions.