Here’s why Slate changed the battery in its cheap EV truck

Slate, maker of the stripped-down EV pickup truck, found another way to simplify its product: the battery.

When the startup revealed its starting price on Wednesday — $24,950 before destination, taxes, and other fees — it also said it had changed its battery strategy, eliminating the optional 240-mile pack but bumping the standard pack from 150 miles to 205. 

How Slate pulled that off illustrates just how significantly the battery market in the U.S. has changed in the past four years.

Initially, the startup planned to use nickel-manganese-cobalt (NMC) cells. The chemistry is widely used in the automotive industry and favored for its energy density, which translates into longer range. But NMC is also expensive, mostly due to high nickel and cobalt prices.

More recently, automakers have begun to use another chemistry, lithium-iron-phosphate (LFP). Battery packs that use LFP are less energy dense but cheaper by about 40%, thanks in part to lower-cost ingredients like iron, one of the main cathode materials, which replaces nickel and cobalt.

There were good reasons why Slate, and other automakers, started with NMC. The LFP supply chain today is today concentrated in China. That wasn’t always the case — early U.S. battery startup A123 Systems was founded to commercialize the technology. But after a few missteps, it fell into bankruptcy and was bought in 2013 by a Chinese auto parts company. Since then, Chinese battery companies have embraced the chemistry and dominated production of LFP cells.

LFP’s foreign origin meant that, before last summer, EVs that used it wouldn’t qualify for a $7,500 tax credit under the Inflation Reduction Act. Only batteries made of materials sourced domestically or from companies with which the U.S. had a free trade agreement would qualify. But when the One Big Beautiful Bill Act axed the tax credits, those concerns evaporated, as well. Chinese manufacturers were back in consideration. Slate said it is working with Hefei-based battery company Gotion to source the cells, which will be built at a factory in Illinois, according to InsideEVs.

The other reason automakers passed over LFP batteries was their limited range. Automakers selling into the U.S. market have prioritized range, though vehicles that can travel more than 300 miles on a charge tend to be pricey — pretty much the opposite of what Slate is going for.

In reality, most people don’t need that much range, and as charging networks have grown in size, reach, and speed, range anxiety is gradually waning. While LFP cells will never match NMC in energy density, modern variations of the chemistry have helped close the gap. Ford, GM, Rivian, and Tesla all offer models that use LFP cells.

The industry’s embrace of LFP cells has also coincided with its transition to cell-to-pack technology, which Slate is using to build its battery packs.

Previously, when automakers assembled a battery pack, they first loaded cells into modules, which were then loaded into the pack. That setup allowed them to use pouch cells, which are cheaper and lighter. But over time, they realized the module approach canceled out the cost and weight savings the pouch cells offered. Though some EVs still use modules, the industry is moving toward cell-to-pack construction, in which rigid batteries, either prismatic or cylindrical, are loaded directly into the pack itself. 

Cell-to-pack trims manufacturing steps and boosts volumetric energy density, a helpful trait for a small EV like the Slate truck. Plus, LFP cells can be charged to 100% with fewer concerns about degradation than NMC, meaning drivers can use the full pack on a daily basis.

While there was probably a moment when Slate’s leadership had to green-light the switch from NMC to LFP, the momentum toward that decision had been building for years. LFP won’t take over the entire market — automakers like GM are betting on an entirely different chemistry — but its combination of low cost and decent range make LFP an obvious choice for what will be the cheapest EV in the U.S.