Solid-state EV batteries just over the horizon for mass market

The race to develop solid-state batteries for electric vehicles is more a speed walk than a sprint. Toyota Motor Corp. and its partner appear to be in the lead, but there's no clear-cut winner.

Solid-state batteries could be a major game changer in the EV market, promising safer, smaller and more energy-dense power storage that would enable electric car and truck makers to offer more range at less cost.

But many researchers say that despite announcements of early production goals before 2030 by Toyota and several other solid-state battery developers, it is likely to be years more before solid-state EV batteries are ready for mass-market application.

"The technology works at small scale, but getting it to the large capacities necessary for cars is a challenge." said Andrew Colclasure, a battery research scientist at the National Renewable Energy Laboratory in Golden, Colo.

The goal is to develop an EV battery than can reliably deliver lots of range, ultraquick charging times and longer life than the batteries in use today. Solid-state batteries can do all that.

They are called solid state because their electrolyte — the component that transfers charged particles, or ions, back and forth between the battery electrodes — is made of solid material while the lithium ion batteries in use today have liquid electrolytes.

The benefits are considerable. Solid-state lithium batteries are far more energy dense than liquid electrolyte batteries. They can pack the same amount of energy into a much smaller and lighter package or, in same-size casing, provide more energy, which translates to a lot more range.

By eliminating the highly flammable liquid electrolyte solutions, solid-state technology also improves EV safety and provides for faster charging times.

The industry goal is 15 minutes or less for batteries with about 300 miles of range. Solid-state batteries can enable that, closing in on the ideal EV charging session that lasts no longer than a gas station stop for a conventional combustion-engine cars and trucks.

Early industry and academic researcher testing also suggests solid-state batteries can be charged without substantial degradation many more times than conventional lithium ion batteries.

The science is there. Solid-state batteries already power medical devices, RFID products and smart watches. However, scaling up the battery size and making it hardy enough to survive the harsh automotive environment greatly increases development and production challenges.

Chief among them are overcoming battery electrode degradation for improved longevity, reducing manufacturing complexity and establishing a secure, stable supply chain. Solid-state batteries use the same chemistries as conventional lithium ion batteries and thus are subject to the same critical minerals constraints.

A major dependability issue stems from the propensity of solid-state batteries with graphite anodes — the most common type — to grow needle-like structures called dendrites when lithium moves to the anode from the cathode. Dendrites can accumulate and grow in the lithium metal that plates the anode with each charging cycle, weakening it and possibly short-circuiting the cell by piercing the barrier separating the anode and cathode.

A major dependability issue stems from the propensity of solid-state batteries with graphite anodes — the most common type — to grow needle-like structures called dendrites when lithium moves to the anode from the cathode. Dendrites can accumulate and grow in the lithium metal that plates the anode with each charging cycle, weakening it and possibly short-circuiting the cell by piercing the barrier separating the anode and cathode.

A second issue is that the electrolyte material used for solid-state batteries tends to crack, swell and break apart as the number of charging cycles increase. Manufacturing and keeping the electrolyte under high pressure is the most common workaround, but that requires tremendously sophisticated and expensive manufacturing equipment.

Toyota and Japan's No. 2 oil refiner, Idemitsu Kosan, have been cooperating on solid-state battery development since 2013 and most recently have targeted release of a commercial quality battery for 2027 or 2028.

That's a few years past their earlier goal of 2025, but still sooner than other announced goals for initial low-volume commercial production.

Toyota is careful to say that developing a market-ready battery doesn't mean releasing masses of them right away. Only after the partnership can produce commercial-quality solid-state batteries will it begin ramping up a supply chain and the facilities to move into mass production, a Toyota spokesman told Automotive News.

Other automakers, including BMW, Ford, General Motors, Honda, Hyundai, Mercedes-Benz, Nissan, Stellantis and Volkswagen are working with battery development partners on solid-state batteries as well. Nissan has announced a 2028 goal for mass production and Honda has set a 2030 goal for its first commercial quality product with mass production to follow.

Battery developers — academic and commercial — also are laboring to come up with the best chemistries to overcome solid-state batteries' biggest challenges.

With all that going on, a future in which solid state takes center stage as the principal battery technology for EVs is certainly foreseeable, said energy storage materials researcher Donald Siegel.

"Now it is really important that developers submit their data so it can be independently tested under realistic conditions. That's when we'll have an idea" of where the finish line lies, said Siegel, chairman of the mechanical engineering department at the University of Texas at Austin.

"We understand solid-state batteries much better than we did 10 years ago, but there is still a lot to work through," he said, predicting it will take another decade to get the technology into full commercial production.