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Despite only two currently released U.S.-market vehicles being built on General Motors’ all-new Ultium platform, the automaker may soon order a huge engineering overhaul to switch from pouch cells to cylindrical cells in the batteries built for its electric cars.
News of the switch comes from the Korean EV publication, The Elec, which claims to have sources with knowledge of the engineering change. In fact, these same sources have pointed the finger at the switch to cylindrical cells as the cause behind the recently announced shelving of GM’s fourth battery plant with LG.
Presently, Ultium uses pouch-style cells that “waste less space [than cylindrical cells] and can stack on top of each other like pancakes or vertically like slices of toast,” rather than be positioned side-by-side with wasted space surrounding each cylinder. The automaker has justified its use of pouch cells thanks to it allowing for flexible packaging and high energy density, though it also quietly benefited from low manufacturing costs as well. However, with the promise of faster-charging, more energy-dense cylindrical cells on the horizon, other automakers like BMW are scrambling to ready their own future platforms to accept battery form factors similar to Tesla’s updated 4680 cells.
Automakers are reportedly switching to the new 4680 form factor thanks to an increase in overall pack density. With the increase in size comes less wasted space, according to The Elec, meaning automakers can pack even more energy storage into a pack than it previously could with cylindrical cells. Plus, with the 46-millimeter-wide cell being available in both 40 mm and 60 mm, OEMs could potentially lower the vehicle’s floor line depending on how it packages each respective configuration.
“The Ultium Platform was designed to be flexible, accommodating a range of cell form factors and battery chemistries,” said a GM spokesperson in a statement to The Drive, declining to comment on speculation.
One of the biggest advantages to the pouch cell during Ultium’s inception, according to the head of General Motors’ global battery cell and electrification strategy, Tim Grewe, was its cost savings. But that doesn’t mean that it’s the only consideration when packaging a battery cell.
“When you put the stack electrode in a can or a pouch, or this or that, truly the pouch has some very clear cost advantages to it,” said Grewe during an interview with The Drive last year. “But everything will coexist in the industry. It has a lot to do with your vehicles and your portfolio, and how you get integrated into the vehicle as well.”
Grewe also made it a point to address modularity and serviceability when speaking with The Drive previously. He noted that it was important that current Ultium pack modules remain serviceable should a failure occur. It’s likely that GM will follow this methodology if it chooses to move forward with cylindrical cells, similar to how other automakers build out their respective packs, though it’s not clear how energy density or module cost could be affected by this change.
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