Established in 2014 in California, Faraday Future (FF) is a global shared intelligent mobility ecosystem company, dedicated to pushing the boundaries with electric vehicle technology. The FF 91 is their flagship all-electric luxury SUV, the foundation of which is the Variable Platform Architecture (VPA). The goal behind the VPA is to have a robust propulsion architecture that can be modified and fitted into different vehicle applications. The battery pack is a key system of the VPA, with the battery cells performing their best at temperatures near 25°C (77°F). As the cells release or store energy, they get hot, so thermal management was a crucial part in ensuring maximum performance during the useful life of the vehicle.
A fully submerged system would allow for scalability and efficiency, and so FF pioneered a patented cooling scheme. The coolant utilised, however, needed to meet a set of strong requisites: It had to be compatible with the battery cells, not be flammable, have low viscosity, and be relatively inexpensive. It also had to enable the FF 91 to achieve an array of spectacular features:
1- Acceleration Time
Utilising liquid immersion cooling, FF aimed to achieve a sub three-second 0-60mph acceleration time – which would eclipse the acceleration times of some of the highest performing supercars in the world.
2- High Energy Density
FF also aimed to achieve one of the highest energy densities of up to 187 Wh/kg, which would deliver impressive range. Thermal management would be imperative in meeting this challenge.
3- High Power Charging
FF believes the future of charging is fast, open and effortless. For charging, while it’s quite simple (on paper) to “go faster” by increasing the current running through the charging cable, the inevitable high heat creates significant engineering challenges and safety concerns.
4- Sustainability Driven Innovation
As a forward-thinking leader in clean energy EV technology, FF is exploring renewable materials, sustainable manufacturing processes and developing new clean energy technologies. The liquid coolant used would need to boast environmental credentials.
The MIVOLT Solution
The thermal properties of MIVOLT allows the pack to have uniform temperature across all its components. With the coolant surrounding every inch of cells, current collectors, and control units, stable temperatures are achieved between modules and strings, enabling the battery pack to better respond to the high demands of the FF 91.
The cooling system eliminates potential risks of corrosion as all electrical components and their connections are submerged. Working with MIVOLT also reduces the spacing between cells and increases the total energy density of the pack, as the liquid can flow freely even at millimetric distances.
FF 91’s pack has around 7000 cells, and with an innovative flow pattern design, the cooling system is able to individually cool each one of them. One of the biggest tests that FF put their cooling system through came when the FF 91 took part in one of the most taxing races in the automotive world: Pikes Peak International Hill Climb. Here, FF demonstrated that their battery pack can perform in demanding conditions and maintain an optimal environment for the cells. The pack has also been tested in cold weather, been driven through Death Valley, from Los Angeles to Las Vegas without stopping for charging, and accomplished many other test drives – giving FF the confidence to say that their battery pack technology is as robust and reliable.
The following features are possible due to the fully submerged cooling system:
Working with a liquid coolant enabled cells to be packed closer together, increasing the total energy density. As a result, FF's lithium-ion battery cells achieve the world’s highest energy density – nearly double that of a production automotive battery.
The FF 91 has been officially certified by the US Environmental Protection Agency to have a rating of 381 miles (613 kilometers) of range, an increase over the initial 378 mile estimate thanks to a larger 142.0 kWh battery than the original 130.0 kWh unit.
FF 91 is has the fastest charge speed currently available, with an ability to charged at a rate of 500 miles of range per hour of charging using DC quick charge stations. This means a full charge should only require about 45 minutes. Supplied with the FF 91, a home charger can fill the battery to 50% in less than 4.5 hours at 240V.
Safety & the Environment
MIVOLT's high fire point, together with its non-toxicity and fully biodegradable status, poses minimal safety and environmental threats. Battery recycling is also easier, as other methods of cooling involve thermal pastes and other materials that can be difficult to remove.
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