Researchers at Watt Laboratory, part of Huawei's Central Research Institute, have used new graphene-based heat-resistant technologies that allow Li-ion batteries to remain functional in a 60°C environment, 10°C higher than the existing upper limit. This allows the graphene-assisted Li-ion batteries to operate twice as long as ordinary Li-ion batteries, potentially up to four years for batteries in infrastructure such as mobile phone basestations.
Three technologies contributed to the development, says Dr. Yangxing Li, Chief Scientist at Watt Laboratory, speaking at the World Battery Symposium in Japan. First, a special additive in the electrolytes can remove trace water and prevent the electrolytes from evaporating in high temperatures. Modified single crystal materials are used for the cathode, improving the thermal stability of the cathode powder and thirdly, graphene allows for more efficient cooling of the Li-ion battery.
"We have performed charging and discharging tests in a high-temperature environment," said Li. "The tests show that when working parameters are the same, the graphene-assisted high-temperature Li-ion battery is 5°C cooler than ordinary Li-ion batteries. Over 70% of the graphene battery's capacity is left after it is recharged 2,000 times at a temperature of 60°C. Less than 13% of its capacity is lost after being kept in a 60°C environment for 200 days."
In high-temperature regions, outdoor base stations powered by the graphene-assisted high-temperature Li-ion batteries can have working lifespans longer than four years. These batteries would also provide a higher mileage for electric vehicles per charge in high temperatures and can also be used for unmanneed aircraft.
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