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The Janus thermal cloak is a blanket for your electric car

13 July, 2023

The Janus thermal cloak is a blanket for your electric car

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Why would an electric car need a blanket? But, to keep it warm of course!

It is a well-known fact that EVs’ autonomy suffers in cold weather. In a test performed by the Norwegian Automobile Federation (NAF) in 2020, the difference between the nominated range by the car manufacturer and the actual range in cold weather was significant. Here’s what they found in their test of 20 of the best selling Electric Cars in the Norwegian market when they tested them under harsh Norwegian winter conditions:

Winter Range Test by the Norwegian Automobile Federation (NAF)

Winter Range Test by the Norwegian Automobile Federation (NAF)

It is apparent that we are witnessing a drop of 18.5% of the nominal range when the weather is cold.

If your electric car is cold, put it under a blanket (well, a Janus thermal cloak)

No, we are not joking. Kehang Cui and his team, materials scientists at Jiao Tong University in Shanghai, created a revolutionary thermal cloak for EVs that offers passive temperature regulation through radiative cooling and photon recycling. The field tests on electric vehicles showed that the cloak achieves nighttime supra-ambient warming by 6.8°C in the winter and daytime sub-ambient cooling by 8.0°C in the summer. This means it heats your car by up to 6.8°C during the night, using no energy at all. Yes, that’s right, the Janus Thermal Cloak (JTC) is 100% passive, requires no energy to run, and does not involve phase change or moving parts, which makes it great for use in real-world applications in buildings, vehicles, and even extraterrestrial environments!


Yes, it can even be used in space. It is also fire retardant, works great in thermal, cryogenic, vibration and corrosive environments and is scalable, meaning you can add more to cover bigger things, like buildings, or your spaceship if you have one. It consists of two types of materials with tailored optical and thermal properties:

  • A solar-blocking infrared radiator facing the sky, and
  • A wideband infrared reflector facing the indoor space (buildings, vehicles, spacecraft, etc.)

What this means is that, depending on whether you need to cool or heat the EV (or whatever other item or space), you just have to swap sides, and let it do its job. No cables, no wiring, no power required at all. One side blocks heat from entering, other absorbs heat.

Janus thermal cloak

Janus thermal cloak

The cloak’s exterior layer comprises delicate silica fibers that have been treated with hexagonal boron nitride flakes. This ceramic material, which is very similar to graphite, boosts the fibers’ ability to reflect sunlight. The fibers are intricately braided, woven, and attached to the inner layer, composed of an aluminum alloy.

So if you want to increase your Electric Car’s range during the winter, just put that blanket over it! We’ll keep you posted when it becomes available on the market.