BMW Plans Move to Structural Battery Packs and ‘46120’ Cells
New energy-dense cylindrical cells earmarked to provide a host of benefits for BMW’s next-generation EVs.
The technology below the smooth skin of BMW’s i Vision Dee concept car, unveiled at CES 2023, marks a major step forward in the company’s electric-vehicle competitiveness. Models based on the automaker’s Neue Klasse EV architecture will ditch today’s rectangular prismatic batteries for the type of large, cylindrical-form-factor cells that Tesla is pioneering with its “4680” cells, so named for their 46 mm x 80 mm dimensions. For its sixth-generation EV batteries, BMW and its battery partners – including China’s CATL and EVE Energy – will adopt even-larger cells of “4595” and “46120” sizes.
At a pre-CES media backgrounder held in Munich in December 2022, Martin Schuster, BMW Group VP for high-voltage batteries, said the new cells pack at least 10% more active battery material relative to their metal cases and are 20% more energy-dense.
For BMW’s Neue Klasse platform, space and weight are saved by using the battery pack as a structural, crash-resistant chassis member: the entire floorpan yawns open until the pack fills the gap. That “pack-to-open-body” design will allow BMW tailor battery sizes to a wide range of vehicles and applications: Pack sizes can range from 75 kWh to a beefy 150 kWh, with motor output ranging from an estimated 268 horsepower to a dizzying 1341 hp (1000 kW). The design also saves more than 10 mm (0.39 in.) in vehicle height, reducing costs and lowering center-of-gravity while improving aerodynamics. BMW executives, including CTO Frank Weber, said the goal is to squeeze more miles from every cell, not to cram ever-larger batteries aboard.
“Going big on cell power and extreme range is not the solution, because the size and weight penalty is counterproductive,” Weber said. “Instead, we must get the best out of every watt-hour by further reducing rolling resistance, improving aerodynamics and increasing onboard energy efficiency.”
Favoring the cylindrical form factor
Compared with more-volatile prismatic cells, whose myriad circuit connections make it harder to protect against runaway heat and potential fires, each heat-shielded cylindrical cell can be individually monitored and isolated to avoid thermal runaway, the engineers noted. The new layout also eliminates a modular structure that required removing the pack to access electronic controls – currently the chief source of BMW EV maintenance issues.
Next, an improved nickel-cobalt-manganese (NCM) chemistry reduces by 50% the cathodes’ content of cobalt (pricey and often ethically sketchy in its sourcing), with 20% less graphite in the anode. Like other automakers, BMW will continue to beef up silicon content in anodes to boost efficiency and performance (BMW also repeated a bold claim to have a 100% solid-state battery in a BMW Group model by 2030).
Executives confirmed the Neue Klasse design also will support lithium-iron phosphate (LFP) cell chemistry for lower-end BMW Group models. LFP, rapidly gaining industry popularity, is less energy dense than the most advanced nickel-rich cells, but makes up for reduced range with lower cost, excellent safety and durability – and no cobalt or nickel whatsoever.
Add it up, and BMW said its nickel-rich cells will boost driving range by 30%. With the company’s highest-stamina EVs currently delivering more than 300 miles (483 km) of EPA-rated range, a 30% jump would let these high-performance machines cover roughly 400 miles (644 km), addressing both range and recharging anxieties. And with batteries responsible for a jaw-dropping 40% of the cost of every BMW EV, according to the engineers, the new cells and other efficiencies will cut BMW’s battery costs by 50% at the pack level, they claimed. That raises renewed hopes for the “price parity” between EVs and conventional ICE models that’s been promised but has proven elusive in showrooms.
Charging boosted, too
There’s more in it for consumers. The Neue Klasse will match Tesla, Hyundai and Kia with a robust 800-volt architecture, for 30% faster DC fast charging at rates well beyond 200 kW, versus a maximum 150 kW in current models such as the i4.
For a company that projects having 10 million EVs on the world’s roads by 2030, the efforts can’t come too soon. While Tesla has struggled to bring its large-format cells to mass production, BMW is confident it can scale up from laboratory to showroom, beginning with a pilot battery plant in Parsdorf, Germany. On the environmental front, the company claims the cells can deliver a 60% cut in C02 emissions over their full lifecycle.
Schuster said that effort extends into the very ground, via partnerships with lithium, nickel or graphite suppliers, and by developing robust supply chains (including in North America’s free-trade zones) that barely exist today. Those supply chains suddenly have every automaker scrambling to set up shop here: President Biden’s bipartisan infrastructure law makes EV consumer tax breaks conditional on final assembly taking place in the U.S., with critical battery minerals sourced from America or its free-trade partners.
“For now, North America is the most difficult place to obtain materials,” Schuster acknowledged. “But we have to have localized materials.”
BMW’s global plans envision six cylindrical-cell gigafactories around the world – two each in the North American zone, Europe and China – each with at least 20 gigawatt-hours of capacity, for a total 120 GWh. In October, BMW and Japan’s Envision AESC announced plans for an $810-million, 30 gigawatt-hour battery factory in South Carolina – powered by 100% net carbon-free energy – to supply cells to BMW’s massive Spartanburg, S.C. factory. BMW plans to have Spartanburg cranking out a half-dozen EV models by 2030, ideally with enough affordable batteries and consumer tax sweeteners to keep business humming.