The likelihood of solid-state batteries replacing lithium-ion batteries is very promising, with several automakers jumping into investments, but full-on adoption is going to be gradual, especially as automakers track battery-electric-vehicle demand in the face of likely U.S. rollbacks in BEV mandates, and the European Union’s response to protests from European automakers about phasing out internal-combustion engines in the next decade.

The action on solid-state batteries today is concentrated among Asian and European automakers, with General Motors and Ford thus far staying clear.

In addition to this month’s announcement by Mercedes-Benz that it has kicked off a program for a prototype re-worked EQS sedan that could extend the BEV’s range from 511 miles (823 km) to 620 miles (998 km) on a single charge, other automakers are chasing higher ranges as well.

Hyundai is developing a solid-state battery, with more details expected next month. A pilot production line is underway at its Uiwang Research Center, with prototype BEVs expected within a year and mass production targeted by 2030. That technology, says one GM executive, is one of the topics being discussed between GM and Hyundai as part of the two companies’ joint venture. The tech will also be shared with Kia Motors.

Spencer Cho, Hyundai Motor Group's Global Product Planning Chief, though, said at a recent Kia EV forum that commercialization and scaling of solid-state batteries doesn't look achievable until at least 2030.

Honda has set up a demonstration facility in Sakura City, Japan, and announced plans to begin producing solid‑state batteries this year. The new process uses a continuous inline mixer to accelerate cell production and is aimed at reducing costs while boosting energy density and battery lifespan.

Stellantis plans to launch a demo fleet of Dodge Charger Daytona BEVs by 2026 using semi‑solid‑state batteries supplied by Factorial. Those batteries promise up to 50% increased range and compatibility with existing lithium‑ion manufacturing processes – a key step toward broader commercialization.

Toyota has signaled its commitment to solid‑state battery technology. Early announcements included plans to introduce solid‑state batteries in hybrids by the end of this year, though not necessarily in the U.S. It has a partnership with petroleum company Idemitsu Kosan to produce solid‑state batteries, with mass production anticipated to begin around 2028.

At a recent Battery Show panel, a Nissan technical manager described solid‑state batteries as “game‑changers” and outlined a roadmap to test, certify and eventually integrate the technology into its vehicles, targeting deployment by fiscal year 2028.

Solid‑state batteries offer exciting potential – better energy density, faster charging and improved safety – but several key challenges are slowing their replacement of lithium‑ion technology:

• Manufacturing scalability issues. The complex production methods needed for solid‑state cells are not yet mature. Scaling these processes to meet the high volume and cost requirements of the auto industry remains a hurdle, especially as many new lithium-ion battery factories are only now coming online.
• Materials limitations. Finding solid electrolytes that combine high ionic conductivity with stability at room temperature is challenging. Many candidate materials suffer from issues like high interface resistance and compatibility problems with lithium-metal electrodes. There are also issues to overcome regarding real-world performance and cell degradation over numerous charge cycles.

“Solid state is still about five years away and maybe further before true mass production happens,” says Wards Intelligence lead battery analyst Adam Ragozzino.  “One of the problems is, battery manufacturers have invested heavily in factories based on the traditional ‘slurry method.’” The slurry method is the traditional “wet process” used to manufacture the electrodes for lithium‑ion batteries, which are the most common type of battery used in BEVs.

“If a solid-state battery doesn’t use the current manufacturing technology, it’s not going into full-scale production anytime soon. Moreover, production of solid-state batteries usually requires a more precise manufacturing process to prevent dendrites (microscopic, tree-like metallic structures that can form on battery electrodes – especially on lithium metal anodes), so the slurry method may not be the most cost-effective solution,” Ragozzino says.

Several Chinese companies have already claimed solid-state production. LiPure, for example, recently established what it calls “the first all-solid-state” production line in China. The line has 2 megawatts of capacity and the batteries are for storage and small mobility applications.

Ganfeng Lithium also claims to have produced a solid-state battery, but at 260 Wh/kg the energy density, notes Ragozzino, doesn’t really match up to expectations. The company is said to be working on its second generation of solid-state batteries with a more respectable 400 Wh/kg energy density. 

The promise of longer ranges, though, has automakers plugging away. While Mercedes-Benz has yet to disclose the full technical specifications of its prototype solid-state battery, it confirms that the EQS’s existing 12-module battery compartment allows for flexible configurations and capacities. The company claims the new energy storage technology offers a 25% increase in range compared to a lithium-ion battery of equivalent size and weight.

Solid-state batteries, though, do not reduce the industry’s dependence on lithium. Most solid‑state battery designs still rely heavily on lithium – often in the form of a lithium metal anode – even though they incorporate new solid electrolytes that can include other metals. Even in solid‑state batteries, lithium is critical for achieving high energy density.