Researchers at University of Maryland and US Army Research Laboratory appear to have developed a powerful solid-state lithium battery. They hope this will do away with the flammable liquid electrolyte in rechargable batteries. Their safe lithium battery with solid electrolyte uses a new, high capacity cathode to produce impressive density. This is as good as commercial batteries while being less likely to explode.
Moreover Their Safe Lithium Battery is Commercially Feasible
Chemical and bio-molecular engineer Chunsheng Wang and his colleagues at the US Army Research Laboratory previously developed water-in-salt electrolytes. They were able to make 4-volt batteries by combining this super-concentrated, sticky lithium salt gel with coated anodes. This was a step towards a safe lithium battery.
However they were convinced they could achieve more by directing their attention to the cathode. This involved understanding how lithium ions move between electrodes. Traditional lithium-ion design combines lithium-metal oxide cathodes and graphite anodes with liquid electrolytes. However this model is inefficient because graphite holds more charge than lithium–metal oxide.
In Hindsight the Solution Was Obvious, It Often Is
Chunsheng Wang and his colleagues at University of Maryland and US Army Research Laboratory decided to go where others failed. Battery scientists had previously tried using pure graphite electrodes in a lithium-salt solution electrolyte. However the large amount of liquid they required meant a bulky battery.
This time, the researchers preloaded their graphite cathode with lithium bromide and lithium chloride powders according to Chemical Engineering News. The beauty is these halide salts don’t dissolve in the highly concentrated gel electrolyte. Consequently the lithium ions don’t consume salt as they charge and discharge the battery. Therefore, there’s no need for a large quantity of electrolyte and a bulky battery.
Their new safe lithium battery produces an energy density of 460 watt-hours per kilogram. This is as good as some of the best commercial batteries. Moreover the risk of thermal runaway is considerably lower. More work is still required, but they seem to be on the right track by avoiding costly cobalt and nickel.
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Preview Image: University of Maryland Appoints Dr. Chunsheng Wang
