Explainer-How could solid-state batteries improve next-gen EVs?

TOKYO/SINGAPORE (Reuters) – Toyota Motor (NYSE:) has said it is moving toward production of solid-state batteries for the next generation of electric vehicles (EVs), bringing a technology that promises more energy storage and faster charging closer to market.

HOW ARE SOLID-STATE BATTERIES DIFFERENT?

Solid-state batteries use thin layers of solid electrolytes that carry lithium ions between electrodes.

The lithium-ion (li-ion) batteries widely in use, by contrast, use liquid electrolytes.

Solid-state batteries have been used in small electronic devices such as pacemakers and smart watches. Mass-market production of the batteries for EVs has been slower to develop.

Toyota said it has overcome an issue with the durability of solid-state batteries that would pave the way for production, which it expects to begin in 2027-2028.

WHAT ARE THE ADVANTAGES OF SOLID-STATE BATTERIES?

They have been called “the grail” of battery development and “the kiss of death” for combustion-engine offerings because of their power and the driving range possible on a single charge.

Solid-state batteries can hold more energy than liquid lithium-ion batteries, a gain that would potentially speed the transition to EVs by addressing a consumer concern: range.

A Reuters poll in March found 35% of Americans surveyed wanted EVs with ranges of 500 miles or more (804 km or more), a distance few currently offer.

Solid-state batteries have also been promoted as a way to reduce charging time.

Toyota said it expects its solid-state battery would have a charging time of 10 minutes or less. By comparison, the Tesla (NASDAQ:) Supercharger network, the largest of its kind, offers the equivalent of 321 km of charge in 15 minutes.

There is also safety. The electrolyte in liquid lithium-ion batteries is volatile and flammable at high temperatures, meaning there is a risk of fire or chemical leaks.

WHY IS IT DIFFICULT TO MANUFACTURE SOLID STATE BATTERIES?

Automakers and technology companies have produced solid-state battery cells for EVs in prototype, but have been unable so far to scale to mass production.

It is hard to design a solid electrolyte that is stable and chemically inert and yet is still a good conductor of ions between the electrodes. They are also expensive to fabricate and prone to cracking.

That has made solid-state batteries far more expensive than liquid lithium-ion batteries.

Toyota did not disclose cost estimates for its new solid-state battery EV or the additional investment it would have to make to ramp up production.

WHO’S TRYING TO MAKE THEM?

Most major automakers – with the exception of Tesla – have disclosed development efforts or partnerships.

Toyota has been pushing solid-state battery development and has teamed with Panasonic (OTC:) on related projects.

Nissan (OTC:) Motor, the first automaker to launch a mass-market EV with the Leaf, has said it is developing solid-state batteries and is working toward mass production by 2028.

Honda is developing solid-state batteries but has not detailed a timeline for bringing them to market.

U.S. battery start-up QuantumScape, backed by Bill Gates and Volkswagen (ETR:), has said it has contracts with six electric vehicle makers, including Volkswagen.

Automotive Cells Co, a venture between Mercedes-Benz, Stellantis and TotalEnergies, has an agreement to develop solid-state batteries with Taiwan-based battery maker ProLogium Technology.

Ford and BMW have invested in U.S.-based startup Solid Power, which is producing prototype batteries. Hyundai Motor, another Solid Power investor, has said it plans to mass produce solid-state batteries by 2030.

Tesla has not detailed solid-state battery development plans. The EV market leader has been focused on the rollout of more powerful 4680 cells for its Cybertruck and other vehicles.