The promise of solid-state batteries is not waning, even as electric-vehicle adoption faces more headwinds now that the EU has revised its 2035 ban.

In both China and the US, progress is tangible, as evidenced by the latest results from companies like QuantumScape and WeLion. Hongqi, a car manufacturer, has committed to bringing the technology to market by 2027. But at what price?

Solid-state batteries are once again being heralded as the technology that will redefine electric vehicles, with the potential to deliver lighter packs, more extended range, and improved safety.

Over the past year, announcements from China, the US, and Europe suggest real momentum. Yet behind the bold numbers and optimism lies a more cautious picture. The outlook for whether laboratory success and pilot lines will translate into affordable, mass-produced cells is still on the horizon.

China and the US

But claims of new milestones keep piling up. These come mainly from the world’s biggest car markets. In China, battery developer Welion has reported laboratory results indicating energy densities well above those of today’s lithium-ion (and competitor solid-state) batteries.

Its researchers say they have reached more than 800 Wh per kilogram under test conditions and claim to be on track to reach figures as high as 1.000 Wh per kilogram.

That is a striking claim, given that most electric vehicles today rely on cells offering roughly a third of that performance. Welion’s pedigree lends weight to the announcement.

The company emerged from a leading state research institute and has already supplied semi-solid batteries for Nio’s 150kWh battery pack, which is now in production. So, this is not simply a laboratory chasing headlines.

First deliveries at MG

But a semi-solid state is easier than a solid-state. The materials needed for sulphide-based solid electrolytes remain expensive, and early applications are likely to be confined to niches where price matters less than safety or weight.

This is evident at MG, which delivered its first semi-solid-state version of the mass-market MG4 in China on Thursday for 68,800 RMB (12,466 euros). The car achieves a range of 530 kilometers from a small 53.9 kWh pack. However, for a full solid-state MG, it is reportedly looking to the Cyberster, which appeals to a much smaller audience.

On the other side of the ocean, California-based QuantumScape has focused less on headline-grabbing energy density – it currently reaches 301 Wh/kg – and more on steady industrial milestones.

The company focuses on securing development agreements with major carmakers. Volkswagen has been an investor for more than a decade and remains the most visible partner, already testing prototype cells on a Ducati motorcycle platform. But the company has now announced that a second top-ten car manufacturer is joining the ranks, though the official name remains under wraps. 

New partner for QuantumScape

QuantumScape pursues a strategy of avoiding building massive factories itself, as scaling production of solid-state technology remains one of the biggest hurdles. Instead, it is licensing its technology to established manufacturers once pilot production has proven successful.

That pilot stage is further taking shape. The installation of automated equipment on QuantumScape’s latest production line marks a shift from hand-built samples to higher-volume production. The company insists this is a foundation rather than a breakthrough, designed to show that its cells can be produced consistently.

In the wake of Nio and MG, China’s traditional carmakers are positioning themselves. FAW Group has indicated that its premium Hongqi brand, the country’s oldest nameplate, could feature solid-state batteries by 2027, starting with small batches.

The projected energy densities are more modest (350-400 Wh/kg) than some laboratory claims, but arguably more realistic for near-term vehicles. Hongqi is a luxury brand, with prices in Belgium ranging from 55.000 euros to 70.000 euros. This customer base will be more willing to pay a premium for next-generation battery technology.

To sum up, these developments indicate a field that is maturing but not yet transformed. Solid-state batteries are moving out of research labs and into pilot lines, partnerships, and limited production plans.