For many electric vehicle drivers, the biggest worry while on the road is the fear of running out of charge. But frantically searching for a charging station could soon become a thing of the past, thanks to a new thermal cloak that promises to make batteries last longer.
The brainchild of Chinese researchers
According to what was published by the British “Daily Mail”, the cloak is the brainchild of researchers from Shanghai Jiao Tong University, and it is designed to keep electric cars cool in the summer and warm in the winter. It should be noted that the cloak performs its function without the need for any external energy input.
“A thermal cloak is like the covering of vehicles, buildings, spacecraft or even extraterrestrial habitats to keep cool in the summer and warm in the winter,” said Dr. Qihang Cui, lead researcher on the study.
The effect of high and low temperature
It is known that the performance of electric cars suffers in extreme cold, because batteries operate less efficiently when temperatures drop to zero and below zero degrees Celsius.
The lithium-ion batteries in most modern electric cars rely on a chemical reaction to store and release electricity, but when it gets colder the process slows down and thus limits battery performance, leading to a significant loss in usable charge range.
ideal temperature
As engineers from the general electric charging company Osprey explain, electric vehicle batteries have an ideal temperature of 20-25 degrees Celsius.
The electric charge stock of the batteries when the weather is hotter is negatively affected because it greatly interferes with the chemical reaction and energy transfer in the battery. So, the researchers designed a thermal cloak that could dampen natural temperature fluctuations.
Silica fibers and aluminum alloys
Dubbed the Janus Thermal Cloak, the cloak has two main components — an outer layer that reflects sunlight and an inner layer that helps trap heat inside. The outer layer is made of thin fibers of silica coated with flake of hexagonal boron nitride, a ceramic-like material. The fibers are braided and woven together into a fabric, before being bonded to the inner layer of aluminum alloy.
Outstanding effectiveness
To assess the effectiveness of the thermal cloak, the team of researchers conducted their experiments on electric vehicles parked outdoors in Shanghai. An open-top car was tested and its cabin temperature reached 50.5 degrees Celsius at midday. But when the thermal cloak was placed on the car, the interior cabin temperature stopped at 22.8°C, 27.7°C lower.
In the middle of the night, the temperature of the cars covered in the thermal cloak never dropped below 0°C, 6.8°C hotter than the temperature outside.
Warming without power input
“For the first time, a warming of about 7°C above the ambient temperature can be achieved during winter nights, and surprisingly, there is no input of energy or sunlight and warming can still be caused,” Dr. Cui said.
real world applications
The team of researchers says the thermal cloak is purposefully designed to make scaling up production easier in the future, and that more large-scale field testing and analysis is underway to translate the metrics and performance of the thermal cloak into real-world economic benefits, such as the percentage of battery life we can increase or The amount of electric energy that would be saved annually if the use of the thermal cloak were extended to vehicles and buildings.
