Waiting impatiently for the arrival of this alternative to the conventional lithium-ion (Li-ion) battery are the automative, shipping and aviation industries among others. One concern is that rising demand for lithium will reverse the long-term decline in the price of Li-ion batteries that has collapsed since they were first commercialised in the early 1990s.

As the former Chief Technology Officer of Britishvolt, Dr Allan Paterson, stated at the launch of a British consortium to develop a prototype SSB: ‘Solid-state is the holy grail of battery solutions. SSBs have the potential to increase energy density significantly over battery technology available today and could dramatically, and positively, change the world of electric vehicles.’

Although Britishvolt collapsed, since that prediction three years ago automakers have made considerable progress. In September 2024, Mercedes Benz and battery start-up Factorial Energy showcased a concept car equipped with a solid-state battery boasting an energy density of 450 Wh/kg, which could increase range by 80% and reduce weight by as much as 40%. By comparison Tesla’s 4680 Li-ion battery cell has a much lower density of 272–296 Wh/kg, according to EV news site electrek.

The shipping sector is even more eager for the arrival of SSBs. Faced with green fuel regulations, emissions deadlines are looming for shipowners, and some can’t get better batteries soon enough. This is an industry which is rapidly embracing electric power. In May the world’s biggest all-electric ferry will be launched for South American operator Buquebus. By virtue of 250 tonnes of batteries, it will transport over 2,000 passengers and 225 vehicles between Argentina and Uruguay. That’s a huge achievement, but SSBs would be even more transformational.

Similarly, in the emerging e-copter market, an SSB-powered rotary aircraft would greatly improve the economic argument. All of these industries see the advantage of a battery that delivers more power for less space and weight while also eliminating carbon.

‘Solid-state is the holy grail of battery solutions. SSBs have the potential to increase energy density significantly over battery technology available today.’ – Dr Allan Paterson, former Chief Technology Officer of Britishvolt

The science
The secret of an SSB is the material used for the electrolyte. As Science Direct explains: ‘Essentially, the key difference from traditional Li-ion batteries is the solid electrolyte which acts as both a separator and a medium for ion transport, enabling faster charging and higher energy density potential.’

One of the world’s largest shippers of batteries, China’s CATL, has over 1,000 researchers working on alternatives to Li-ion. Globally, scientists are exploring what is the best solid material for the electrolyte – ceramic, polymer, glass or something else?

Toyota is basing its hopes on a sulphur-based electrolyte, while Samsung is focused on silver-carbon. Either way, solid-state materials are seen as more thermally stable, inorganic materials that mitigate against the risk of leaks, fires and explosions compared to their highly flammable Li-ion liquid-based counterparts. Indeed, SSBs can withstand higher temperatures than Li-ion alternatives.

So, where are we at with SSBs?

According to EV Magazine, Samsung is aiming for mass production by 2027, after establishing a pilot assembly line just two years ago. The first automobile manufacturer off the blocks could be China’s BYD (Build Your Dreams) EV manufacturer which plans to put SSBs in its most expensive models. Meanwhile, compatriot NIO is working with BYD to explore a potentially disruptive route to market with ‘semi-SSBs’ where Li-ion batteries will be swapped out for SSBs at dedicated stations.

Toyota is in collaboration with Panasonic, which plans to sell its SSB technology into industry in the form of robots and drones.

In Europe, Volkswagen is well down the road in a partnership with America’s QuantumScape and has set a date for mass production before 2030. QuantumScape is basing the future on Li-metal SSBs that it promises ‘will charge faster, go farther, last longer and operate more safely than today’s EVs and gas-powered vehicles [and] bring us closer to that lower carbon future’.

QuantumScape has been working for 15 years on what it claims is: ‘A patented solid ceramic electrolyte separator that keeps the anode and cathode from touching and moves Li ions from one side of the battery to the other during charge and discharge. The technology creates the Li anode in situ during the first charge, an innovation that dramatically simplifies battery design and makes it fundamentally cheaper to manufacture.’

‘The solid electrolyte allows use of Li-metal for the anode, which is the lightest metal on the planet and nearly 10 times more energy dense than what’s used in today’s batteries. And the ceramic separator is non-flammable and non-combustible, making the batteries safer than conventional lithium-ion batteries.’

Faraday Institute research
A heavyweight consortium of British researchers is progressing on the holy grail that Britishvolt’s Dr Paterson outlined four years ago.

But today the stakes are even higher and the race more intense. Global SSB revenues from sales of SSBs to EV manufacturers alone are expected to reach $8bn by 2030, and then grow even more rapidly through 2040 and 2050.

A late-2024 update from the Faraday Institute showed that Germany is leading the way in Europe in the number and capacity of battery manufacturing plants announced or under construction, closely pursued by six other European countries.

The UK is lagging far behind, according to Faraday: ‘UK battery manufacturing plants announced or under construction are expected to reach a combined capacity of 57.6 GWh by 2030.’ That’s just 4% of total European GWh capacity and ‘more needs to be done’.

An entirely new supply chain is required to fill the voracious needs of battery gigafactories for cathodes, anodes, electrolytes, separators and cell casings among other components.  There is a mounting problem of competition for critical raw materials such as lithium, nickel, cobalt and graphite, as manufacturers fight for binding contracts with countries that are lucky enough to have them, such as the US, Canada, Australia and South America, in what is known as the ‘lithium triangle’.

Consumer electronics revolution
Although the automotive industry, and especially public transport, is waiting impatiently, the solid-state revolution will probably start elsewhere. ‘Early deployment of SSBs is likely to be in consumer electronics, niche automotive applications and unmanned aerospace, before being used in broader EV markets’, predicts the Faraday Institute. By 2030, SSBs are likely to take a 7% share of the global consumer electronics battery market and a 4% share of the EV battery market.

Many difficulties remain. Although it’s not hard, at least for a scientist to create an SSB, it must be made sufficiently powerful in the lab to justify mass production at commercial scale in a factory. ‘There are fundamental scientific challenges that need to be addressed before high-power SSBs with commercially relevant performance can be realised,’ explains the Faraday Institute.

But those challenges are being overcome, and not just in SSBs. Although it is much further over the horizon, the Li-sulphur battery is under development. As with SSBs, its advantage over Li-ion is considerable, according to researchers at University College London. Li-sulphur can store more energy per unit weight, operates over a wider range of temperature, and is safer and cheaper.

However, ‘widespread use of Li-sulphur faces major hurdles that stem from sulphur’s insulating nature, migration of discharge products leading to the loss of active material, and degradation of the anode’, according to researchers. Yet given past performance in battery development, it seems likely that these hurdles will be cleared eventually.

It’s a powerful reminder of the pace of energy science that as recently as 2019 three scientists – Akira Yoshino, M Stanley Whittingham and John B Goodenough – were awarded the Nobel Prize in chemistry for their work on the ‘rechargeable, renewable Li-ion battery’ because, as the Award Committee said, they had ‘laid the foundation of a wireless, fossil fuel-free society’.

By then batteries had been the primary form of energy in countless kinds of electronics for nearly 30 years. But as we see, their breakthrough is running out of time. Even as the race for the mass production of SSBs accelerates, others have their eyes on the next breakthrough – the quantum battery.

As an article in early 2025 in the Atlantic Council’s scientific forum points out: ‘These novel batteries store energy by drawing on quantum mechanics and quantum chemistry, which is crucial to battery research and allows scientists to understand the chemical structure and reaction of atoms at significantly quicker speeds than current models.’

When they become available, quantum batteries are likely to be applied first in medical science, for instance in cochlear implants and pacemakers and, in the event of emergencies, as alternative power for hospitals.

But they are still years away, whereas their solid-state cousins are just around the corner in the next great energy revolution.

• Further reading: ‘Northvolt’s collapse dents Europe’s battery ambitions’. Sweden’s Northvolt, once heralded as Europe’s best hope of challenging the dominant Asian battery manufacturers, has filed for bankruptcy in Sweden. The company’s collapse is a significant setback for the European battery and electric vehicle sectors, highlighting the challenges of competing in a sector dominated by heavily subsidised competitors from China and the US.
• The global battery industry is at a pivotal moment, driven by soaring demand and falling prices, according to the International Energy Agency. Meanwhile, the industry continues to innovate and scale in size, as highlighted by an electric vehicle battery cooling ‘first’ from TotalEnergies and the energising of Europe’s largest operational battery energy storage system (BESS).