It sounds like science fiction, or at the very least vaporware, but zinc-air batteries are a technology that now allows more power density to be packed into batteries for power storage. A new single-atom catalyst has now pushed the power density to record levels. This type of technology may push battery technology forward to help make the storage of clean energy more affordable and efficient.

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Are zinc-air batteries the future of power storage?

So what is a zinc-air battery? Batteries store energy in the form of chemical energy for later use, and zinc-air batteries do this by using platinum as a catalyst to allow chemical reactions that optimize power storage. You may not be familiar with zinc-air batteries because they’re less common than lithium ion batteries that power your laptop or alkaline batteries like you use in a flashlight. However, zinc-air batteries are commonly used in button batteries for watches, hearing aids and garage door openers, so they are already a common technology.

Related: A new solid-state EV battery never loses charge capacity

Now scientists at the TU Dresden, Max Planck Institute for Chemical Physics of Solids (MPI-CPfS) and HZDR have developed a new catalyst with base metal zirconium that can replace the precious metal platinum for record-level power density and cheaper operation. It is this type of technological advance that will allow power storage technology to catch up with solar and wind generation clean energy production to allow storage of all the clean energy coming online for the grid.

When you have optimal power storage, you have flexible grid capabilities to store daytime solar for nighttime use, for example. This take the crunch out of peak energy demand prices during the evening rush for charging electric cars and home appliances.

The new catalyst for zinc-air batteries significantly improves the battery’s charging and discharging capabilities. It is durable as well — 130 hours of operation still results in a 92% retention rate of the battery’s original current. 

“This is an excellent value considering that we are still in the early development stages,” said Dr. Agnieszka Kuc from the Institute of Resource Ecology at Helmholtz-Zentrum Dresden-Rossendorf. Her job is to research the chemical-physical properties of battery catalysts. The technology is in its early days, but it is possible that this breakthrough might inspire other breakthroughs in catalyst technology to create other new kinds of batteries for clean energy storage as well.

Why battery catalysts control power storage and output

Catalysts are often used in the form of metal nanostructures on suitable support materials, the metal atoms acting as catalytically active sites. Size of metal particles is vital to the performance of catalysts. Catalytic effectiveness of metal atoms tends to increase the smaller the metal particles that house them.

“The ultimate frontier is the single-atom catalyst: isolated metal atoms individually distributed on a support,” explained Dr. Minghao Yu of TU Dresden. He works with catalysts such as single transition metal atoms, such as zirconium. “In our case, however, we have also an oxygen atom as an additional coordination partner above our metal, which leads to further interaction with the electronic structure of the zirconium.”

This special ability could lead to a new design for single-atom catalysts and zinc-air battery technology. Oxygen is also plentiful and inexpensive. Batteries tend to be made of expensive and hard to source metals and chemicals. The more plentiful the ingredients, the less harmful to the environment, and the more efficient they are in storing and transmitting power, the more efficient and inexpensive clean energy becomes.

How zinc-air batteries from zirconium increase efficiency

The catalyst reduces the effects of a phenomenon that limits the efficiency of electrochemical reactions: the so-called overpotential, which measures the deviation of the real chemistry in the battery cell from what could be expected theoretically.

“This basically means that we can harness less energy than thermodynamics predicts,” Kuc explained.

Catalysts can reduce overpotential and make conversion of chemical to electrical energy more efficient. Platinum is considered the current standard for efficient reactions in batteries, but its status as a rare precious metal makes it expensive.

Base metal zirconium is much cheaper, which is why it was the focus of the research in Dresden, which aimed to make a more practical battery with high efficiency and lower cost. To make it all work, the scientists had to address a common problem: decreasing particle size can lead to agglomeration of particles in small clusters which limits performance. By using a carrier material that interacts with the metal to prevent agglomeration, the scientists in Dresden created a stable finely distributed cluster of metals with high catalytic activity, which allowed the catalysts to achieve high levels of performance.

“In our case, we isolated our synthesized material on the surface of quartz spheres, which have a porous structure advantageous for catalytic processes. In our arrangement, we found a pronounced aversion of zirconium to agglomeration, so we were able to produce catalysts with a high zirconium load. As a result, we have achieved a record-breaking power density among all zinc-air batteries previously made with single-atom catalysts,” Kuc said.

The findings were published in the journal “Angewandte Chemie International Edition.”

Via Tech Xplore

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