Rivian joins BMW in planning a move to approximately fist-sized 4695 cylindrical lithium-ion cells from the shotgun shell-sized 2170 cells, with a deal to source the new batteries from LG Energy Solution. Tesla started the push to 46mm-diameter cells when it switched to 4680 cells (46mm diameter x 80 mm height) for the Model 3.

As with BMW's Neue Klasse EVs, the Rivian R2 compact SUV will employ 46-mm cells that are 95 mm tall. BMW has also announced the intent to use 120 mm versions, which are about the size of a 248-milliliter can of Red Bull.

There are multiple advantages to using larger cells. Using a smaller number of larger cells reduces the number of connections to be made when assembling battery modules, simplifying the manufacturing process. Additionally, power pours into and out of these larger cells faster than it does in smaller ones, potentially boosting vehicle acceleration and shortening charging times.

Each of the 4695 cells packs about six times as much energy as Rivian’s current 2170 cylindrical cells, and the company predicts that the assembly of the smaller number of cells into modules will be streamlined by about 45 percent as a result. The larger cells are also more thermally stable, making them safer than the small-diameter batteries used currently.

Related:Rivian Reveals Some Tech Details of its $45,000 Compact Models

BMW estimates that its 4695 cell-based packs will trim the 10-to-80 percent charge time by 30 percent compared to its current EVs. Rivian’s R2 battery pack will be a 1000-volt system (nominally 979.2 volts), compared to BMW’s planned 800-v architecture for its upcoming Neue Klasse EVs, so Rivian’s vehicles could charge even faster that than.

“Due to the dynamic nature of the current EV market, an increasing number of global automakers are demonstrating a strong preference for a diverse range of battery form factors,” said David Kim, CEO of LG Energy Solution. “This large-scale order from Rivian for 4695 batteries marks a key milestone for LG Energy Solution in expanding its client base within the cylindrical battery segment.”

The five-year supply agreement between the companies will total 67GWh of batteries. Production of the batteries will shift to LG Energy Solution’s stand-alone plant in Queen Creek Arizona within a year of the start of production.

That will ensure a shorter domestic supply chain and will make the R2s eligible for Inflation Reduction Act tax rebates. The Rivian R2 is scheduled to arrive in 2026, presumably using batteries sourced from existing foreign LGES plants for the first year.

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While the cells are the big news, Rivian says it will also refine the battery pack architecture to create a simplified pack structure that reduces weight, complexity, and cost while also providing greater energy density. The company promises a “meaningful reduction” in the pack’s dollar-per-kilowatt-hour (kWh) metric compared to the existing R1 models.