New catalyst makes zinc-air batteries rechargeable up to 500 times
The new material could make batteries with up to five times the energy density of lithium-ion batteries suitable for practical use
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zinc-air batteries can store significantly more energy than lithium-ion batteries, but until now have been virtually impossible to recharge. A team led by Professor Jörg J. Schneider from the Department of Chemistry has now demonstrated how a material made of iron, nickel and carbon enables the battery to be charged and discharged up to 500 times.
They have been used in hearing aids for decades: zinc-air batteries. They are technically mature and wide spread, but they have one major drawback: once they are discharged, they end up in the bin. Rechargeable versions have so far been rare on the market. Yet they have great potential. In theory, zinc-air batteries can store up to five times more energy than the lithium-ion batteries widely used today. The main stumbling blocks are their full rechargeability and the complex chemical processes within the cell, which are technically difficult to control. This is precisely what makes the topic so exciting for basic research.
The research group led by Professor Jörg J. Schneider from the Department of Chemistry at TU Darmstadt has now described an important step towards a rechargeable zinc-air battery in the journal ‘Advanced Science’. The team has developed a new material and investigated its electrochemical properties; this material acts as a particularly efficient and long-lasting catalyst within the battery. The material is based on so-called spinels. This group of minerals is widespread in nature; one example is trevorite, a compound of nickel, iron and oxygen. In chemistry, materials science and electrical engineering, spinels are already used in a variety of ways due to their special properties.
The Darmstadt researchers have directly and firmly attached tiny spinel particles – just a few nanometres in size – to carbon nanomaterials. In addition, the elements nitrogen and phosphorus are incorporated into the carbon surface. This creates a composite material capable of performing several functions simultaneously: it conducts electricity, is chemically stable and activates the battery’s key element, oxygen.
A zinc-air battery utilises oxygen from the ambient air. During discharge, oxygen undergoes a chemical reaction; during charging, it must be re-formed again. Both reactions can only proceed with the aid of a catalyst. The search for materials that consistently support both processes effectively is of central importance. The new catalyst achieves precisely this: in experiments, it enabled up to 500 charge and discharge cycles. A crucial factor here is a kind of ‘meeting point’ within the battery where three key players must come together: the solid catalyst, the liquid electrolyte solution – which facilitates charge transport – and the oxygen from the air. Only if this contact area – referred to by experts as the ‘triple junction’ – remains stable during operation will the battery function reliably. The new composite material creates favourable conditions for this.
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Topic World Battery Technology
The topic world Battery Technology combines relevant knowledge in a unique way. Here you will find everything about suppliers and their products, webinars, white papers, catalogs and brochures.