Research into energy storage systems continues. Picture: panthermedia.net/phortcach (YAYMicro)
The German engineering website Ingenieur.de published an interesting article today on energy storage, mentioning Zinc8 with its patented zinc-air flow battery competing with lithium-ion batteries. The article chas been translated into English with the help of Google-Translate.
Whether laptop, smartphone or electric car: The lithium-ion battery is currently the predominant battery technology. Despite its many advantages, the battery, which was developed in the 1970s, has its limitations. With the zinc-air battery, the next system is already in the starting blocks and could replace the lithium-ion battery within a few years.
Lithium-ion battery and zinc-air battery in comparison
Zinc-air batteries are not a novelty in themselves; many smaller disposable batteries, but also devices that require an uninterrupted flow of current, are occasionally used. Unlike lithium-ion batteries, the production of zinc-air batteries is resource-saving, because all raw materials used are available in abundance and can be extracted very easily and at low cost. A zinc-air battery can even be 98% recycled and the manufacturing costs are very low at around ten Euro per kilowatt hour. A further development is correspondingly attractive for industry and science, because this battery form has the potential to store energy in a greener and cheaper way than previous systems.
In addition, a zinc-air battery has many advantages and these have something to do with how it works. The primary reaction of electron release requires sufficient oxygen, therefore some leeway is needed to really bring the oxygen to the reaction surface. This may sound like a small disadvantage at first, but it also means that zinc-air batteries cannot discharge in an oxygen-depleted environment. If stored correctly, a full charge is possible for up to ten years.
Also, the electrical capacity is significantly higher than that of a lithium-ion battery, around three times the charging capacity can be stored in the same space. This is particularly important for electric vehicles, as their range is seen by critics as an essential shortcoming. The combination of low weight and high charge is so crucial here to enable electric mobility over long distances.
Neither the Lazy-Battery Effect nor the Memory Effect occur with zinc-air accumulators. The Memory Effect describes a loss of capacity during frequent partial discharge. Here, lithium-ion batteries have already offered an enormous leap in performance compared to the nickel-cadmium battery that dominated before, and the zinc-air battery is the next logical step in development. These accumulators are also free of the Lazy-Battery Effect, a voltage loss over the discharge time.
The functioning of zinc-air batteries
During discharge, the zinc in the cell reacts with the oxygen in the air. This oxygen hits the cell through a permeable electrode. With only one reaction partner in the cell, a zinc-air battery enables a higher energy density than comparable batteries. However, this has a decisive disadvantage: During the reaction, zinc oxide is produced as a waste product, which would have to be reduced and converted back into zinc for recharging. The resulting crystalline deposits can lead to short circuits. There are various research approaches that deal with this problem.
At the University of Bayreuth, for example, they try to incorporate a reduction of zinc oxide into the accumulators without impairing their function. The Canadian company Zinc8, for which the North Americans have already received an award from the New York Power Authority, is pursuing a different approach.
The state of research and findings of Zinc8
A Canadian company called Zinc8 is currently working hard to develop the next generation of zinc-air batteries to make lithium-ion technology largely obsolete.
Over a total development period of 14 years, the company has invested $84 million USD to prevent the formation of crystalline zinc residues on the battery. The focus of the research is usually the use of an electrolyte to remove the zinc residues (the dendrite). Zinc8, on the other hand, has developed a process that does not remove the dendrite but forms large particles. These can then be stored back in the battery so that it can be used as a rechargeable battery with a high charging capacity without any problems. However, not only several years of development time will be necessary until then, but also the required licenses and safety approvals will take their time. Even Zinc8 does not expect the first commercial use until 2023.
However, the Canadians have several advantages that play into their cards. On the one hand, there is the support of the New York Power Authority and cooperation in the construction of a prototype that is to demonstrate the long durability of the load. On the other hand, there is the [non-existing] competition – there is currently a gaping void in the market for long-term storage of energy.
The future of zinc air batteries
Of course, zinc-air batteries are already in use, for example in hearing aids. But with further development stages, the zinc-air technology could finally take the next step. This means that this type of battery could also be used in larger devices such as tablets and laptops, and could even become interesting for large-scale use as a storage device in the power grid.
All this currently requires years of research, but the benefits are tangible. For example, zinc-air batteries are not only significantly more energy-efficient than lithium-ion batteries, they are also, above all, more environmentally friendly. This is because both the production and recycling of lithium-ion batteries are environmentally harmful, as the batteries are difficult to recycle and the mere material value does not cover the recycling costs. This is different with zinc-air batteries, because they can be almost completely recycled very easily and very efficiently, whereas also the production could be carried out in Germany without major problems, all the way from mining to the finished battery.
