BASF has supported RML Group in the development of an innovative, immersion-cooled battery for a high-performance hybrid hypercar that sets new performance and safety standards using next-generation plastic materials. The 800V battery features a capacity of 4.2 kWh and a discharge rate of >100C, weighing in at less than 75kg.

The extremely high-power output, especially during rapid acceleration and regeneration, requires a cooling system capable of rejecting the heat generated by the cells. To prevent extreme temperatures and ensure a more even temperature distribution throughout the pack, immersion cooling is used, which greatly improves the entire battery system’s efficiency and service life. Two BASF plastics are used in RML's battery unit.

First, there is Ultramid B3EG7 (PA6GF35) both as the housing material for the battery unit itself and in the housing of the high-voltage electrical components of the battery control system. This plastic is noted for its robustness and high resistance to mechanical stressing, which is particularly important for the battery housing.

The design not only has to satisfy crash requirements, but also must pass the UNCE Reg 100.03 fuel fire test. Protected only by a thin carbon sheet integrated into the test as a body part, Ultramid B3EG7 passes the fire test without damage to the housing, making it ideal for this application.

Second, Ultramid A3EG6 EQ (PA66GF30) is used as the material for the individual battery cell holders within the battery housing. The Ultramid EQ grades (EQ = Electronic Quality) are extremely pure-grade, i.e. they contain hardly any electrically active or corrosion-promoting contents and still deliver outstanding heat aging resistance. In contact with the dielectric fluid, the material minimizes any kind of diffusion out of the material. Since dielectric fluids are used for electrical insulation and as coolants in high-voltage applications, contamination by contact materials must be avoided at all costs.

RML is a pioneer in the electrification of the automotive fleet through its development, design and production of novel and highly innovative battery systems. Particularly noteworthy is the close cooperation between BASF and RML even at the development stage and the early involvement of BASF as a materials supplier in decision-making processes.

With its extensive expertise in the new battery sector and in the field of electrical and electronic (E/E) materials, BASF managed to accelerate the development of the overall battery unit significantly. The rapid recommendation of suitable materials as well as the timely, global delivery of sample quantities were instrumental in ensuring that RML was able to meet its ambitious schedule for this project. BASF’s agile approach underscores its commitment to providing solutions that meet the evolving needs of the automotive industry.