![]() Tesla described a new pack design that reduces some of the structural supports, which means more cells in less volume. That makes the engineering of the pack very much relevant to the overall energy density of the vehicle’s storage, and therefore its range. There’s a lot going on in these battery packs, including charge management, cooling, and safety measures in case of fire. Pack it up, pack it inĪn EV doesn’t run on a battery cell, of course, but rather a battery pack full of cells. That will help them reach cost reduction goals and ramping output goals. And together with other changes we’ll get into in a moment, they’re talking about increasing production while using less factory floorspace and less energy. The tabless design actually helps with this, as the electrode sheet can just keep flying through the rollers. As detailed in our companion story, Tesla has found ways to substantially increase the throughput of portions of the battery line. ![]() ![]() The other half of making a new kind of cell is designing the machines that do the making. It’s genuinely hard to know precisely how this stacks up with cells used in other EVs, given how secretive manufacturers are, but it could be that this tabless design validates Tesla’s choice to stick with the cylindrical cell shape. The longer path for electrons causes problems for safe rapid charging and creates more heat that has a harder time escaping. But going bigger presented Tesla with challenges because a bigger can holds longer rolls, and longer rolls mean the anode and cathode stretch out farther from the tab connecting them to the battery terminals. This cylinder was 21 millimeters by 70 millimeters rather than the 18 by 65 dimensions of the 18650 cell. Tesla did this when it introduced the 2170 cell with the Model 3 and Powerwall. Obviously there are limits to how much you can shave off, so another way of doing this is increasing the ratio of battery volume to packaging area. Make the separator super thin and minimize the space-eating outer container and battery pack components, and you’ve got more electricity stored per kilogram. One of the best ways to make a battery more energy dense is to get rid of as much packaging as possible. The cathode and anode sheets each have one skinny “tab” that connects to the positive and negative terminals of the battery can. In a cylindrical cell, long sheet-like anodes, separators, and cathodes are sandwiched, rolled up, and packed into a cylinder-shaped can. Tesla got off the ground using existing and commonly available cylindrical 18650 lithium-ion cells, while most EVs have been built with flat pouch or prismatic cells (more like the thin batteries in phones and laptops). Let’s start with two things Tesla claimed already exist at its pilot production plant: its new cell design and some improvements in manufacturing. But we can compare all this to other industry trends and to published research to get some idea. Without specific numbers or concrete details, assessing the announcements takes a little guesswork. Further Reading How Tesla plans to make batteries cheap enough for a $25,000 car
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