Lithium batteries for new electric vehicles, resistant to high temperatures

An American company has developed a new type of lithium-ion battery that can work safely at high temperatures at a higher energy density than existing lithium-ion batteries, according to a recent report in the Massachusetts Institute of Technology's Technology Review. Now, if the energy density of batteries used in electric or hybrid vehicles is too high, there are safety problems.

Leiden Energy replaced the aluminum collector and lithium hexafluorophosphate used in traditional battery electrolytes with graphite collectors and sodium imide, increasing the battery life while working well at temperatures above 60 °C. Moreover, the energy density of the new battery is 50 % higher than that of lithium ions used in electric vehicles.

Lithium-ion batteries are widely used in consumer electronics, but some design improvements are needed to ensure that they can work safely in electric cars or hybrid cars. Now, carmakers are forced to use less energy-dense batteries and use electronic equipment and cooling systems to ensure that the batteries do not overheat. For example, Tesla Motor Company uses batteries used by laptops to provide electricity to its Luocite sports car; Use liquid coolants, heat management electronics, and software to prevent battery overheating and other problems.

Cathode materials such as lithium-ion phosphate can resist high temperatures, so they are sometimes used as batteries for electric vehicles, but their energy density is low. Leyden will focus its improvements on electrolytes and collectors that affect battery cathode and anode performance and determine battery life and stability.

The new battery replaces lithium hexafluorophosphate with sodium imide. Lithium hexafluorophosphate does not react with the water inside the battery. This reaction significantly reduces the battery life, while sodium imide does not. Lithium hexafluorophosphate decomposes at room temperature and its efficiency is significantly reduced at 55 °C, while sodium imide does not decompose at higher temperatures.

However, sodium imide can also cause trouble, it will corrode aluminum collectors in general batteries, so Leiden used graphite to resist this corrosion.

The new battery could be cooled with air coolant instead of liquid coolant, Bartel said, which would reduce costs and make the battery lighter. The company is also developing batteries to manage electronics and software to prevent overcharging or undercharging batteries. Leiden recently received $2.96 million from the state of California to build 10 car battery cases a month.

"Leyden's battery technology has a real advantage in terms of heat management, battery life cycle and energy density," said Brian Wiseman, product development director for Brahmo, an American maker of electric motorcycles. "

The company said it hopes the new technology will be used first for laptops, which can be recharged 1,000 times, up from 300 times today.

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