EV pioneer Rimac is “not a huge fan” of current batteries
Rimac’s upcoming EV, the 1914-horsepower C_Two, stores all its juice in a liquid-cooled H-shaped battery unit containing 21,700 cylindrical lithium-ion cells, and weighing a whopping 1330 pounds in itself. Granting the car an energy density of 120 kWh and a peak power output of 1.4 megawatts, Rimac says its battery represents a good balance between power and energy density, as well as between cycle life and charging speeds. However, in terms of energy density per mass, it’s still very far from a splash of flammable fuel.
The poor gravimetric properties of batteries have been troubling inventors since the 19th century. Due to all the heat, drivetrain, friction, and chemical losses, an internal combustion engine can only turn 25–35 percent of its fuel’s energy content into kinetic energy. The same ratio goes up to 50 percent in current Formula 1 power units. In comparison, an electric motor provides 90–95 percent efficiency without breaking a sweat. However, the batteries powering that electric motor will continue to counter the benefit by having an energy content per pound 50–100 times worse than gasoline.
The cooling of such high-performance battery packs is also a lot more complex, adding further weight to an already-handicapped package full of non-renewable and quite toxic resources. Where does all this leave us in 2020? Pretty much where we were five years ago.
Carmakers have made it pretty clear already that, due to the massive packaging challenge of batteries, we’ll need something the size of a Hummer to produce a full-size battery electric vehicle. That’s why most major players have been looking into fuel cells for now. The mass and the size of the energy storage pack has to go down in order to achieve balance. However, as we’re right in the middle of the transition period to BEVs, all we can hope for is a major breakthrough in battery technologies.
As Mate Rimac points out, though they’ve been teased for a while, solid-state units are unlikely to work in every current lithium-based application; yet, when it comes to all the headlines alerting us about new chemistries and other wizardry, we’re yet to see another followup product. All this suggests slow and steady evolution instead of a revolutionary switch to the next big thing—which is supposed to be much smaller, actually.