How salt can up energy storage capacity

Researchers have found that adding salt to metal oxides increases their energy storage capacity by increasing their surface area.

The team, including researchers from Drexel University in the US, Huazhong University of Science and Technology (HUST) and Tsinghua University in China, published the results in the journal Nature Communications.

The results show that using salt crystals as a template to grow thin sheets of conductive metal oxides make the materials turn out larger and more chemically pure -- which makes them better suited for gathering ions and storing energy.

"The challenge of producing a metal oxide that reaches theoretical performance values is that the methods for making it inherently limit its size and often foul its chemical purity, which makes it fall short of predicted energy storage performance," said Jun Zhou, an author of the research, said.

"Our research reveals a way to grow stable oxide sheets with less fouling that are on the order of several hundreds of times larger than the ones that are currently being fabricated," Zhou, who is also a professor at HUST's Wuhan National Laboratory for Optoelectronics, added.

In theory, the best materials for the job should be thin sheets of metal oxides, because their chemical structure and high surface area makes it easy for ions to attach -- which is how energy storage occurs.

But the metal oxide sheets that have been fabricated in labs thus far have fallen well short of their theoretical capabilities, the paper said.

"This method of synthesis, called 'templating' -- where we use a sacrificial material as a substrate for growing a crystal -- is used to create a certain shape or structure," said Yury Gogotsi, another author of the paper.

"The trick in this work is that the crystal structure of salt must match the crystal structure of the oxide, otherwise it will form an amorphous film of oxide rather than a thing, strong and stable nanocrystal. This is the key finding of our research -- it means that different salts must be used to produce different oxides," Gogotsi added.

--IANS

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