TECH FILE: Spray-Based Immersion Cooling to Boost Battery Safety

The Korea Institute of Machinery and Materials (KIMM) has unveiled what it says is the world's first spray-based immersion cooling technology for lithium-ion battery packs, a development that could improve thermal management and fire safety while dramatically reducing the amount of dielectric coolant required.
Developed by a research team led by Dr. Jinsub Kim at KIMM's Heat Pump Research Center, the system combines two cooling approaches: dielectric liquid is sprayed directly onto the tops of battery cells while the bottom portion of the pack remains partially immersed in the same non-conductive fluid. The hybrid approach enables direct heat removal through liquid contact while forced convection from the partially immersed section enhances overall cooling performance.
In testing with an actual lithium-ion battery pack operating at a 4C charge-discharge rate—representative of aggressive fast-charging conditions—the technology maintained cell temperatures below 35°C, a critical threshold for minimizing thermal degradation and reducing the risk of thermal runaway.
The most notable engineering achievement may be efficiency. Conventional immersion cooling systems require battery packs to be completely submerged, adding significant weight, cost and coolant volume. KIMM's approach reportedly reduces dielectric-liquid consumption by approximately 85%, using just 10-20% of the coolant required by traditional immersion cooling while maintaining comparable—or better—thermal performance.
The reduction has important implications for transportation applications where weight is critical, particularly electric vehicles, marine battery systems and high-power commercial vessels pursuing rapid charging between operations. Lower coolant volumes also reduce system cost and simplify packaging.
Beyond mobility, the technology could prove valuable for stationary energy storage systems and data centers, where lithium-ion battery safety has become an increasing concern. Because the dielectric liquid is non-flammable, it not only cools the cells but may also help suppress fire propagation should a thermal event occur.
Unlike conventional air- or liquid-cooled battery systems that rely on heat sinks or cold plates to indirectly remove heat, spray-based immersion cooling places the coolant in direct contact with the battery cells, significantly improving heat transfer during high-power operation.
Looking ahead, the KIMM researchers plan to use artificial intelligence to identify new dielectric fluids with optimized thermophysical properties that further enhance cooling performance.
The research was conducted under South Korea's Ministry of Climate, Energy and Environment's Core Technology Development Project for Energy Demand Management and was published in Applied Thermal Engineering (Vol. 282, 2026).
For the maritime industry, where battery-powered ferries, offshore vessels, harbor craft and hybrid propulsion systems continue to grow in both size and charging power, technologies that simultaneously improve thermal management, reduce system weight and mitigate fire risk could become an increasingly important element of next-generation battery architecture.

Facts Only

* The Korea Institute of Machinery and Materials unveiled spray-based immersion cooling technology for lithium-ion battery packs.
* The system involves spraying dielectric liquid onto the tops of battery cells while the bottom remains partially immersed in the fluid.
* The hybrid approach enables direct heat removal via liquid contact and forced convection from the submerged section.
* Testing with a 4C charge-discharge rate showed cell temperatures below 35°C.
* Conventional immersion cooling requires complete submersion, adding weight, cost, and coolant volume.
* The technology reportedly reduces dielectric-liquid consumption by approximately 85%.
* This method uses only 10-20% of the coolant required by traditional methods while maintaining comparable or better thermal performance.
* The research was conducted under South Korea's Ministry of Climate, Energy and Environment's Core Technology Development Project for Energy Demand Management.
* The research was published in Applied Thermal Engineering (Vol. 282, 2026).

Executive Summary

The Korea Institute of Machinery and Materials developed a spray-based immersion cooling technology for lithium-ion battery packs, aiming to improve thermal management and fire safety while reducing the use of dielectric coolant. The system operates by spraying dielectric liquid onto the tops of battery cells while keeping the bottom immersed in the same non-conductive fluid. This hybrid method allows for direct heat removal via liquid contact while forced convection from the submerged section aids cooling. Testing with a battery operating at a 4C charge-discharge rate showed cell temperatures remained below 35°C. A key advantage is efficiency, as this approach reportedly reduces dielectric-liquid consumption by approximately 85% compared to conventional immersion cooling, using only 10-20% of the coolant volume while maintaining thermal performance. This reduction in fluid use has implications for weight and cost, particularly in transportation and stationary energy storage. Furthermore, the non-flammable nature of the dielectric liquid offers an added safety benefit by potentially suppressing fire propagation during thermal events, offering potential advantages across various applications like electric vehicles, marine systems, and data centers.

Full Take

The narrative centers on achieving significant performance gains—thermal management and material efficiency—by fundamentally altering the heat transfer mechanism from indirect conduction to direct contact. The most salient pattern is the trade-off: reducing bulk coolant volume (an environmental/cost factor) while maintaining or improving thermal integrity. This speaks to a systemic pressure in high-power density systems where weight reduction and safety are inextricably linked, particularly in sectors like maritime transport. The move toward AI optimization for dielectric fluids suggests that the physical process is now being extended into a domain of materials science refinement, implying that the next frontier of efficiency lies not just in hardware architecture but in discovering optimal operational chemical properties. The implication for systemic change is whether this type of material-process innovation can be rapidly scaled across diverse industrial applications where safety and energy density are paramount concerns. What assumptions are driving the demand for these specific efficiency metrics versus established, albeit less efficient, methods? How will the societal cost-benefit analysis shift when a marginal efficiency gain in cooling translates directly into reduced operational weight or enhanced fire suppression capability in critical infrastructure?