Direct liquid cooling, a game-changer in battery thermal management

Author: Manex Larrañaga Ezeiza, PhD, Battery Engineer at CIDETEC Energy Storage

The electrification of road transport is no longer just a trend—it is a key step in reducing carbon emissions and addressing climate change. Beyond environmental benefits, it also carries strategic and geopolitical importance, prompting major automotive manufacturers to invest heavily in electric mobility ¹.

The success of this transformation depends on a crucial element: the battery system. For electric vehicles to thrive, their batteries must deliver high energy density, durability, fast charging, strict safety, and affordability. Among all energy storage technologies, lithium-ion batteries offer the highest performance, making them the preferred choice for electric vehicles. Their exceptional energy storage capacity, high discharge rates, long cycle life, and low maintenance have established them as the industry standard. However, their performance and lifespan are highly temperature-sensitive, making advanced thermal management crucial to ensuring efficiency, safety, and long-term reliability ² .

As battery technology evolves, traditional cooling methods are losing effectiveness. Indirect liquid cooling, the dominant strategy in the electric vehicle market, often falls short in high-demand applications. The electrical conductivity of the coolant fluids used in this approach necessitates insulation for system safety, resulting in indirect heat transfer. This limitation reduces cooling efficiency and introduces thermal inertia, slowing response times and compromising overall system performance.

In recent years, direct liquid cooling has emerged as a breakthrough technology in battery thermal management ³. This approach utilizes dielectric fluids—specialized liquids with low electrical conductivity—that can be in direct contact with battery cells eliminating thermal barriers without compromising safety. Additionally, this method has the capacity to enhance safety aspects by mitigating risks such as thermal runaway, as the dielectric fluid acts as a protective buffer to prevent catastrophic chain reactions. By enabling faster charging, improving safety, and extending battery lifespan, direct liquid cooling meets the evolving demands of the electric vehicle industry.

One of the most advanced direct liquid cooling techniques is immersion cooling, where battery cells are fully submerged in a circulating dielectric fluid. While immersion cooling offers precise temperature control, it also requires a larger volume of fluid, potentially increasing system weight and energy consumption. To address these challenges, new strategies are being actively developed.

At CIDETEC Energy Storage, we are pioneering next-generation direct liquid cooling solutions tailored to Electric Vehicle (EV) applications. Our research focuses on optimizing cooling performance while minimizing drawbacks such as excess weight and volume use. Through extensive testing under real-world conditions and benchmarking against industry standards, we refine our designs to integrate seamlessly into modern EV systems. By exploring advanced dielectric fluids and adapting solutions to various battery cell formats, CIDETEC is unlocking the full potential of direct liquid cooling.

In this context, CIDETEC has patented an innovative cooling strategy based on the Partial Direct Liquid Cooling approach ⁴. This strategy overcomes the drawbacks of both conventional methods and emerging solutions like immersion cooling. It enables precise and direct thermal response control of the cells while implementing a targeted surface cooling system that significantly reduces the amount of fluid and overall volume required. These characteristics make CIDETEC’s solution highly suited to the current demands of the electric vehicle market, offering a novel approach with high efficiency, precise control, and seamless system integration that will enhance battery performance, safety, and longevity.

At CIDETEC, we collaborate closely with industry leaders to bring these innovations to market, driving the development of more efficient, sustainable, and reliable battery technologies for the future of electric mobility.

Chemistry and engineering must advance hand in hand to deliver efficient, affordable, sustainable, and safe batteries to the market. Neither discipline alone can achieve this goal. In this regard, CIDETEC’s mission is to address the technological challenges that arise in both fields. Through its commitment to excellence, CIDETEC brings together a highly skilled, multidisciplinary team of chemists and engineers who work in perfect synergy, leveraging their expertise to develop breakthrough technologies that push the boundaries of energy storage. This dedication to innovation is also reflected in the cutting-edge facilities of CIDETEC Energy Storage’s headquarters, showcasing the future of energy storage solutions. With a strong focus on innovation and industry-driven research, CIDETEC not only meets the evolving demands of today’s market but also anticipates future needs, ensuring long-term technological progress. By designing and implementing tailored solutions, CIDETEC plays a key role in facilitating a smooth and efficient transfer of cutting-edge technology to industries in the Basque Country and beyond, reinforcing its reputation as a pivotal force in the energy storage sector.

The BRTA is a consortium that remains a step ahead of future socio-economic challenges worldwide and in the Basque Autonomous Community; it addresses them through research and technological development, thus projecting itself internationally. The BRTA centres collaborate to generate knowledge and transfer it to Basque society and industry so as to make them more innovative and competitive. The BRTA is an alliance of 17 R&D centres and cooperative research centres with the support of the Basque Government, the SPRI and the Chartered Provincial Councils of Araba, Bizkaia and Gipuzkoa.