Li-Air Battery Lifespan Improves

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The AMaLiS 2.0 research project, initiated by IOLITEC Ionic Liquids Technologies also involving multiple research organizations, achieved a innovation lead to improve the stability and lifespan of Li-air battery by using a membrane that separates the positive and negative electrodes, allowing for different electrolytes on each side. The purpose of this innovative concept is to create a stable, rechargeable prototype using advanced materials and membranes.

Research project, titled, “Alternative materials and components for aprotic Li-air battery: chemistry and stability of inactive components – AMaLiS 2.0,” is initiated by a Germany based company IOLITEC Ionic Liquids Technologies, with an intention to improve the stability of this novel Li-Air battery type. The MEET (Münster Electrochemical Energy Technology) Battery Research Center at the University of Münster and the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Bremen are also the part of the project AMaLiS 2.0. 1.1 million euros funding projection is also approved by the Federal Ministry of Education and Research over a three-year period.

Li-air batteries, also known as lithium-oxygen batteries, are the future of high-energy electricity storage devices. The new innovative concept AMaLiS 2.0 research project is in under testing to increase the stability and lifetime of the battery cells. The focus of this innovative concept is to separating positive and negative electrodes using a membrane coated on both sides. This indicates that different electrolytes can be used on both sides of the membrane. In addition, the researchers also planned to test a novel gas diffusion electrode made of nanostructured titanium carbide.

The Working Concept of Li-Air Battery

The working concept of Li-air battery is quite similar to the conventional battery types, but the electricity generation in this type of battery occurs due to the reaction of lithium ions with oxygen from the air at the positive electrode. The big advantage is that Li-air batteries can store almost as much energy per kilogram as fossil fuels. This property makes Li-Air battery lighter but similar energy storage capable and due to this advantage it is quite useful in electric cars as well as in stationary energy storage. “However, before we get that far there are still a chain of technical challenges to be solved. One of these challenges is the shortage of electrolyte that are chemically stable at both the positive and the negative electrodes. These conductive fluids or solids are located in the area between the two electrodes.

In Li-air batteries, one of the electrodes is made of metallic lithium while the other – called the gas diffusion electrode – consists of a porous porous network and conducting material where oxygen (O2) from the air is reduced in an oxidation-reduction reaction. When the battery is discharging, positively charged lithium ions move across the electrolyte from one electrode to the gas diffusion electrode, where they combine with oxygen and electrons from an external electrical circuit to form lithium oxide. This generates an electric current which can be used to provide energy for electrical devices. During charging, lithium, and oxygen separate once more and the ions and electrons travel in the opposite direction.

To increase the stability of the Li-air battery, the project team aims to design a membrane that separates the positive electrode from the negative electrode, thus allowing different electrolytes to be used on either side. “This would significantly expand the options for electrolytes,” says IOLITEC’s project coordinator Dr Thomas Schubert. The scientists plan to test a separator with a special coating on each side that protects both the lithium electrode and the gas diffusion electrode.

The Oldenburg team led by Wittstock is using various methods, including surface spectroscopy and scanning electrochemical microscopy (SECM), to investigate the processes on the surfaces of the separator and electrodes. IOLITEC is developing the separating layer together with a team from MEET Battery Research Center at the University of Münster which is headed by Verena Küpers. “We are testing different coatings that are specifically adapted to the challenges posed by each type of electrode,” Küpers explains.