Korean researchers develop spray immersion cooling tech to prevent lithium-ion battery fires

A spray immersion cooling chamber. [Korea Institute of Machinery and Materials]

South Korean researchers have successfully developed a spray immersion cooling technology capable of effectively cooling lithium-ion battery packs and reducing the risk of fire.

A research team led by Kim Jin-seop, a principal researcher at the Heat Pump Research Center of the Carbon Neutrality Mechanical Research Institute under the Korea Institute of Machinery and Materials, developed the spray immersion cooling technology using non-conductive liquid to reduce the risk of thermal runaway and fire in lithium-ion battery packs. The method directly sprays non-conductive liquid onto the upper section of the battery pack while partially submerging the lower section, and the team verified its superior temperature control performance under rapid charge-discharge conditions in actual lithium-ion battery packs.

The technology brings non-conductive liquid into direct contact with battery cells to rapidly remove heat. Liquid is sprayed directly onto the upper portion of the battery pack, while the lower portion is partially submerged, generating additional cooling through convection. The combination of upper-spray cooling and lower-convection cooling delivers high overall cooling performance, keeping battery pack temperatures stably below 35 degrees Celsius even under rapid charge-discharge conditions.

Conventional air-cooling and water-cooling technologies rely on indirect methods using heat sinks or cold plates, which struggle to keep battery pack temperatures in check during summer heat or rapid charge-discharge cycles. Immersion cooling — which brings non-conductive liquid into direct contact with the battery — has drawn attention as a solution, but existing approaches require fully submerging the entire battery pack, raising concerns about the cost and weight of the large volumes of liquid required. The newly developed spray immersion cooling technology reduces liquid usage to just 10 to 20 percent of what conventional immersion cooling requires, while improving cooling performance, achieving both greater thermal stability and a lighter overall weight.

Unlike full immersion cooling, which submerges the entire battery pack in non-conductive fluid, the spray immersion method submerges only a portion — between 10 and 50 percent — of the pack. The non-conductive fluid circulates via a pump and is sprayed onto the top of the battery pack, with flow rate controlled at 2 to 4 liters per minute. The charge-discharge rate, or C-rate, is precisely regulated from 1C to 4C through a dedicated battery charge-discharge device.

Principal researcher Kim Jin-seop (right) operates a battery charge-discharge device. [Korea Institute of Machinery and Materials]

The significant reduction in non-conductive liquid usage also lowers weight and cost, broadening the technology's potential applications beyond electric vehicles to large-scale energy storage systems. The non-conductive liquid is also non-flammable, meaning it can act as a fire suppressant should a battery fire break out.

As safety concerns over lithium-ion battery fires and thermal runaway have grown, the technology is expected to improve battery safety across a range of sectors, including electric vehicles and data center energy storage systems. The research team has identified the thermal properties of various non-conductive liquids that maximize cooling performance, and plans to expand the research by using AI to discover new non-conductive liquids capable of delivering optimal cooling.

"Spray immersion cooling technology can effectively cool lithium-ion battery packs using only a small amount of non-conductive liquid, reducing the risk of thermal runaway and fire," Kim said. "It will have wide-ranging applications in preventing thermal runaway in high-output, high-heat electric vehicle batteries and in reducing battery weight."

The findings were published in the international journal Applied Thermal Engineering.

nbgkoo@heraldcorp.com