O2FREE project aims to develop and validate an Al-air primary battery with high O2 absorption rate for cargo compartment inertisation during ETOPS time. During discharge, metal-air batteries consume oxygen from the surrounding air and thus have the capability to extract oxygen and inert the ambient air. Oxygen absorption capability is directly coupled to the power capacity of a metal-air battery (Ah), and this is currently the limiting factor for realizing such application. A major focus of the O2FREE project is on increasing the power performance of Al-air technology through the development of advanced anode and cathode materials for Al-air cells and optimization of the module configuration.

Metal-air batteries are inherently a safe and reliable technology. Moreover, aluminium is the third most abundant element in the earth’s crust, highly recyclable and non-flammable. Thus, O2FREE delivers a safe, lightweight and environmentally friendly technology free of critical raw materials with high recycling potential. All these advantages are aligned with European Union policies for airborne sustainability.


O2FREE project will be carried out by three partners with extensive knowledge and experience in the energy storage and aerospace sectors covering the full value chain for this project. LEITAT and AES have been working for years in the development of post Li-ion battery technologies including metal-air systems and are specialized in electrochemical processes, technology optimization through the development of novel materials and components, as well as module design and integration. SON is expert in structural design and manufacturing for the aerospace sector and will leverage their expertise for turning this technology into a product that meets the stringent requirements for installation and operation of this type of battery in future aircrafts.

Al-air shows the overall best trade-off for performance, lightweight, safety and reliability versus Zn-air and Li-air while also being the most mature technology of the non-commercial metal-air technologies. O2FREE proposes the development of metal-air fire suppression battery based on Al-air technology. As shown in the Figure 1, Al-air battery is composed on porous air cathode where the ORR (oxygen absorption) takes place, aluminium anode (alloyed with other metals in order to supress the Al-corrosion) and electrolyte between them that acts as an ionic conductor. O2FREE propose to use a proved high performant and cheap commercial alloys, improving the Al utilization and its resistance to high current ranges thanks to the addition of different additives. Moreover, the project will develop a Carbon nanofiber-base cathode that will increase the fire gasses tolerance of the cell. Finally, O2FREE will develop an electrolyte able to work at high range of temperature and pressure with the addition of some additives that will help to supress the al corrosion.

Figure 1. Schematic electrochemistry of an Al-air battery.


O2FREE proposes the development of an innovative and lightweight solution for fire suppression based on primary Al-air battery technology. Metal-air batteries consume oxygen during discharge and thus have the capability to suppress fires in closed compartments such as aircraft cargo bays by reducing oxygen concentration.

O2FREE will demonstrate the feasibility of such technology. Battery gravimetric power capacity is considered the critical factor for reaching high oxygen absorption capability. O2FREE proposes the development of Al alloys (anode) and nanofibers with optimum porosity (cathode) to enhance Al-air cell power capability. Moreover, 1S12P module configuration will be developed to maximize power output of the battery module and thereby oxygen absorption rate per kg of battery. Battery prototypes containing single battery modules will be developed for testing and validation. Modules will be placed in aluminium casings designed for protection and to allow air to reach cells, meeting the standards of aeronautics sector including RTCA DO160 Rev G.

O2FREE will demonstrate the feasibility of Al-air technology as a fire suppression solution for aeronautics; delivering a lightweight, safe and reliable technology free of critical raw materials. Results will directly contribute to EU competitiveness in aircraft systems and technologies.