Soon, better performing batteries with improved safety

ANI | Updated: Nov 24, 2017 03:36 IST

Washington D.C. [USA], Nov 24 (ANI): A team of researchers has brought batteries with better performance and improved safety closer to reality.

Researchers from Empa, the Swiss Federal Laboratories for Materials Science and Technology, and the University of Geneva (UNIGE), Switzerland, have devised a new battery prototype: known as "all-solid-state", this battery has the potential to store more energy while maintaining high safety and reliability levels.

Furthermore, the battery is based on sodium, a cheap alternative to lithium.

The team focused on the advantages of a "solid" battery to cope with the heightened demand from emerging markets and to make batteries with even better performance: faster charging together with increased storage capacity and improved safety. Their battery uses a solid instead of a liquid electrolyte that enables the use of a metal anode by blocking the formation of dendrites, making it possible to store more energy while guaranteeing safety.

"But we still had to find a suitable solid ionic conductor that, as well as being non-toxic, was chemically and thermally stable, and that would allow the sodium to move easily between the anode and the cathode," explained researcher Hans Hagemann.

The researchers discovered that a boron-based substance, a closo-borane, enabled the sodium ions to circulate freely. Furthermore, since the closo-borane is an inorganic conductor, it removes the risk of the battery catching fire while recharging. It is a material, in other words, with numerous promising properties.

"The difficulty was establishing close contact between the battery's three layers: the anode, consisting of solid metallic sodium; the cathode, a mixed sodium chromium oxide; and the electrolyte, the closo-borane," stated Leo Duchene.

The researchers dissolved part of the battery electrolyte in a solvent before adding the sodium chromium oxide powder. Once the solvent had evaporated, they stacked the cathode powder composite with the electrolyte and anode, compressing the various layers to form the battery.

The team subsequently tested the battery. "The electro-chemical stability of the electrolyte we are using here can withstand three volts, whereas many solid electrolytes previously studied are damaged at the same voltage," said Arndt Remhof, leader of the project.

The scientists also tested the battery over 250 charge and discharge cycles, after which 85% of the energy capacity was still functional. "But it needs 1,200 cycles before the battery can be put on the market", noted the researchers. "In addition, we still have to test the battery at room temperature so we can confirm whether or not dendrites form, while increasing the voltage even more. Our experiments are still ongoing."

The study appears in the journal Energy and Environmental Science. (ANI)

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