Solid-state batteries: The holy grail of energy?

Imagine an electric car that charges as fast as a petrol car refuels, travels hundreds of kilometres farther without a heavier battery, stays cooler, occupies less space, and carries a lower risk of fire.

That imagination might not be so far from reality.

Solid-state batteries are almost here to solve the problems that are holding people back from switching to electric cars. They promise to tackle all of them at once.

That is why they have become the most fiercely pursued technology in the battery world, drawing in almost every major carmaker and technology firm into investment.

While the decade has already seen another battery revolution — the silicon-carbon battery technology that we see in the new Chinese phones — the new solid-state technology is far superior.

These batteries promise faster charging, improved safety and longer range. They replace the liquid electrolyte inside today's lithium-ion batteries with a solid material.

That single change has turned a niche research topic into a global race involving Toyota, BMW, Volkswagen, Honda, Samsung, CATL and a long list of startups. Billions of dollars are now tied to a technology that is still stubbornly difficult to perfect.

The promise

Engineers have long regarded solid-state batteries as the holy grail of energy.

In theory, they can store more energy in less space and reduce the fire risks linked to flammable liquid electrolytes. They also open the door to lithium metal anodes, which could push driving ranges far beyond current limits.

Toyota has said a solid-state battery could allow an electric car to travel close to 1,000 kilometres on a single charge, with charging times of around 10 minutes.

QuantumScape, backed by Volkswagen, claims its prototype cells could deliver a clear jump in range and survive hundreds of thousands of miles with little degradation.

The appeal goes beyond cars — solid-state batteries could reshape consumer electronics, industrial machinery and even aviation. China's CATL has spoken of condensed matter batteries that might power electric aircraft.

Additionally, for governments chasing climate targets, the technology offers a faster route to wider electric adoption.

A crowded race

Despite the excitement, there is no single definition of a solid-state battery. Some designs are fully solid. Others are semi-solid, using gels or hybrid materials. Each approach carries trade-offs between performance, cost and durability.

That has not stopped companies from placing their bets. Toyota plans commercial use later this decade, after years of delays. BMW is working with Solid Power, which has delivered test cells using a sulfide-based solid electrolyte. Mercedes-Benz and Stellantis are backing Factorial Energy. Honda has opened a test production line to understand how solid-state cells might be built at scale.

South Korea's Samsung SDI, LG Energy Solution, and SK On all have active programmes. China's Nio has already put semi-solid batteries into limited commercial use, offering ranges close to 1,000 kilometres through its battery swapping network.

ProLogium, based in Taiwan, has opened what it calls the world's first solid-state battery gigafactory, with plans to expand into France.

Why it is still so difficult

For all the announcements, solid-state batteries remain elusive. The problems are not theoretical, rather physical. Solid materials expand and contract during charging. Over time, that movement can cause cracks, poor contact between layers and rapid loss of performance.

Manufacturing is another barrier. Solid electrolytes are often sensitive to moisture and contamination. What works in a lab can fail on a factory line.

The appeal goes beyond cars — solid-state batteries could reshape consumer electronics, industrial machinery and even aviation. China's CATL has spoken of condensed matter batteries that might power electric aircraft.

Toyota's recent patents focus less on chemistry and more on controlling production conditions, which shows how unglamorous the hardest work can be.

Cost also looms large — manufacturing solid-state cells are still far more expensive than conventional lithium-ion batteries. Scaling production without sacrificing reliability is the challenge that will decide who wins and who fades.

Most experts now expect solid-state batteries to appear first in small volumes and premium vehicles. They will be tested quietly before being trusted at scale. Even optimistic forecasts place high-volume production by the end of this decade.

Carmakers face tightening emissions rules and intense competition. Battery makers need the next leap forward as lithium-ion technology matures. Solid-state batteries sit at the intersection of both pressures.