CoC HITMOBIL’s Invention Is IEES-BAS’s Most Outstanding Scientific and Applied Achievement of 2025
A single-layer gas diffusion electrode (GDE) for rechargeable metal hydride–air batteries
The most significant scientific and applied achievement of IEES-BAS for 2025 was presented at the joint Annual Reporting Meeting of the General Assembly of Scientists and the Scientific Council of IEES-BAS, held on 28 January 2026.
The development of the “Single-layer Gas Diffusion Electrode (GDE) for Rechargeable Metal–Air Batteries” was accomplished with the support of the equipment infrastructure and financial funding provided by the HITMOBIL Center of Competence project. The innovation is the result of the work of a research team led by Assoc. Prof. Borislav Abrashev, PhD, and Assist. Prof. Valentin Terziev, PhD, from IEES-BAS. In 2025, the invention was granted intellectual property protection in the form of Patent No. 67713 B1, issued by the Bulgarian Patent Office.
The electrode is intended for application in the production of batteries characterized by high energy density, long operational lifetime, and low manufacturing and operating costs, while simultaneously meeting environmental requirements regarding both the materials used and the production process.
The gas diffusion electrode features a single-layer structure in which no distinction is made between the gas diffusion layer and the catalytic layer—they are integrated into a monolithic composite structure. Through direct mechanical mixing of selected raw materials in specific weight ratios followed by sintering, an electrode is obtained with electrochemical characteristics and mechanical properties comparable to, or exceeding, those of conventional multilayer gas diffusion electrodes.
The primary advantage of the single-layer gas diffusion electrode lies in eliminating the need for the separate deposition of a catalytic layer, significantly reducing the complexity, duration, and cost of the manufacturing process. Additional benefits include the ease of scaling and technology transfer—from laboratory fabrication using a press and die to industrial production via extrusion and rolling. The technology can be adapted by modifying the type and quantities of the raw materials as well as the configuration of the current collector. It can also be integrated with other types of metal electrodes in rechargeable metal–air battery systems.
The combination of selected raw materials within the proposed single-layer structure represents an effective alternative for the broader adoption of gas diffusion electrodes in mass production, particularly in the context of growing demand and rising electricity costs.
The development was carried out using equipment and financial support provided by the CC HITMOBIL.