Patented technologies to prevent electric vehicle battery fires

  Recently in Korea, a large fire broke out in an apartment parking lot due to an electric vehicle fire. As many as 140 cars were burned, and more than 100 residents were forced to evacuate their homes to temporary residential housing due to the toxic gas generated by the fire and the power and water outages.

Apartment parking lot where an electric vehicle fire broke out
<source: ohmynews, https://n.news.naver.com/mnews/article/047/0002443110?sid=102>

  There have been electric vehicle fires before, but this fire is said to be the most severe in terms of the scale of damage and impact. Is there a technology to prevent electric vehicle battery fires? In this issue, we will look at some of the technologies available for this.

Technology to extinguish fires in the battery pack itself

  In the case of this Mercedes-Benz vehicle, the fire that started in the car was not extinguished first, so it spread into a larger fire. As electric vehicle battery fires are frequent, it seems necessary to establish a function and system that can extinguish fires on its own in the early stages when a fire occurs. Among the existing patented technologies, there are technologies that can extinguish battery fires on their own in the vehicle.

  First, this is the technology of LG Energy Solution, a representative electric vehicle battery manufacturer in Korea. Recent battery modules contain a large number of secondary batteries to improve energy density, so if an explosion occurs in one cell, there is a risk that other cells may explode in a chain reaction. Therefore, LG Energy Solution developed a battery pack that can effectively suppress the thermal runaway chain reaction from a battery module where a fire occurred to other battery modules to improve this problem.

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KR10-2022-0106396, Battery pack with enhanced fire safety

  This battery pack has a cooling pipe that supplies coolant, and when a danger detection signal is received from a fire detection sensor, the valve opens to quickly flow coolant into the battery pack.

  SK On, a leading electric vehicle battery company along with LG Energy Solution in Korea, has also developed a technology that can prevent fires in batteries themselves. This invention is a battery pack that includes a firewall that can control the heat transfer phenomenon due to battery fire. It was also developed to prevent the problem of heat from a battery module that caught fire from being transferred to other cells. To solve this problem, SK On chose to build a heat-absorbing firewall in the battery pack.

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KR10-2020-0093791, Sandwich fire wall and battery pack comprising the same

  The heat-absorbing firewall contains various flame retardants such as brominated flame retardants and chlorine flame retardants, and is said to absorb heat at about 110-150 degrees with a thickness of 0.12-3 mm. In fact, the technology to place a thermal runaway prevention sheet between battery cells has already been commercialized with conventional technology, but it has been pointed out that its effectiveness is low because it has a wide range and only exhibits heat absorption at very high temperatures of 400 degrees or more.

  This heat-absorbing firewall of SK On consists of an electrode assembly in which the cathode and anode are alternately laminated with a separator as the boundary, and a pouch outer material that surrounds the electrode assembly. Therefore, it can cover the fire heat more densely and respond to relatively low and medium fire temperatures, thereby solving the above problem.

The following is Hyundai Mobis' technology.

  Hyundai Mobis has also developed a battery system with its own fire extinguishing function. This system is equipped with a fire extinguishing fluid storage unit between multiple battery cells so that the extinguishing fluid can be released directly to the ignition point of the battery cell in the event of a fire.

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KR10-2018-0004239, Battery system with fire-off function

 The battery pack is equipped with a fire-extinguishing fluid circulation device that maintains the pressure of the fire-extinguishing fluid in the event of a fire, enabling continuous supply to the ignition point. It is a useful system that can effectively prevent a chain fire by quickly extinguishing a fire.

Technology to prevent fire with battery case and cover

  Technologies that prevent fire with the outer case or cover, not the battery itself, have also been filed. Sung Woo Hitech, a partner of Hyundai Motor Company, has developed a battery case and battery module pack equipped with a fire extinguishing function. It is said that the battery case is equipped with a fire extinguishing agent to prevent thermal runaway or fire in the battery module.

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KR10-2022-0155614, Battery case with fire extinguishing function, battery module and battery pack including the same

  This battery is equipped with a fire extinguishing agent inside the double-structured battery case. In the event of a fire caused by thermal runaway, the fire extinguishing agent is sprayed to quickly suppress the fire. In addition, the fire extinguishing agent is directly released through the melted area (fused site?) due to the rise in temperature, preventing the battery management system (BMS) from malfunctioning.

  The technology jointly developed by Hyundai Motor Company and Kia Motors is also notable. This technology also prevents fire using the battery cover. To be precise, it is a suffocation extinguishing technology that tightly wraps the battery and blocks the oxygen supply to the furnace that can cause a fire. The battery cover is located under the battery cell, the cover opens from the bottom up to quickly cover the fire when a fire is detected.

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KR10-2022-0137221, Fire extinguishing system for battery for vehicle

  Electric vehicle batteries mainly use lithium cathodes rather than carbon, so if exposed to oxygen in the event of a fire, the possibility of oxidation or explosion is very high. The two companies focused on this and devised a method to prevent fire by blocking oxygen.

Technology to extinguish fire from outside the vehicle

  If the above technologies are to extinguish fires inside the vehicle, there is also technology to extinguish fires from outside the electric vehicle. This one is a ‘fire extinguishing system that responds quickly to fires in electric vehicle batteries’ developed by Renault Korea Motors. This technology is designed that when a fire extinguishing cap is installed on the outside of the vehicle and fire extinguishing water is injected from outside the vehicle, the fire extinguishing water is directly sprayed onto the battery pack through the fire extinguishing pipe.

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KR10-2023-0165124, The fire extinguishing system responding to fire in electric vehicle battery

  The feature of this technology is that it can spray water directly on the battery pack where the fire started. The downside is that it requires external fire extinguishing water, so it seems difficult if the sprinkler does not work or if no one discovers the fire.

A thorough technological improvement is needed

  As the electric vehicle distribution rate is rapidly increasing, the recent electric vehicle fire in Korea has caused even greater shock. It has gone beyond a simple fire and has led to a public debate. In order to prevent future disasters, the cause of electric vehicle battery fires must be identified and thorough technological improvement must be followed.

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