Solid state batteries could revolutionise EVs

What is a solid-state battery?

So-called because they have solid electrolytes rather than using liquid or gel like a lithium-ion alternative, solid-state batteries allow electric ions to move faster during charging and discharging giving them a greater tolerance to high voltages and temperatures.

Are solid-state batteries better than lithium-ion batteries?

Pound for pound a solid state battery can pack more power than a conventional battery, offering up 1,200 watt-hours per litre versus the 700 watt-hours of a conventional battery.

Early solid state batteries are expected to offer a range of more than 620 miles between charges next to the 520 miles you can eke out of a lithium-ion battery-powered Lucid Air, which has the longest range of any current EV courtesy of a mammoth 112kWh power pack. But 620 miles is just the start, advanced solid state batteries are projected to offer a range of double what a conventional EV is capable of, giving them a longer range than even the most economical of diesels. 

While the battery tech will be the driving force in improving range, a solid-state battery’s compact size will also pay dividends. Conventional batteries are essentially a slab of cells hidden in a car’s floor – it's why many EVs are SUVs because the upright shape helps hide the battery. Because solid state batteries are more power dense, they can be lighter and smaller – as much as 50 per cent shorter – so they require less energy to move and can be accommodated in a sleeker shape, with a reduced frontal area and a lower drag coefficient that improves efficiency, perfect for an EV.

Finally, solid state batteries can be safer than a conventional lithium-ion battery because they don’t need a flammable liquid electrolyte and run at lower temperatures that reduce the likelihood of thermal runaway.

Disadvantages of a solid-state battery?

Until now, solid state batteries have had a shorter life than conventional alternatives because their fast charging speeds derogate the electrodes inside the battery. Dendrites (branch-like scars) damage the battery’s electrodes, producing cracks that can cause a short circuit.

However, Harvard University is working on a solution that uses silicon to prevent dendrite growth. It’s working on a solid-state battery capable of 10,000 charge cycles – double what you would expect of a lithium-ion battery. Toyota is also working on the problem and expects to have a scalable solution by 2028.

Are solid-state batteries the only answer?

Not necessarily. Opinion is divided on exactly what the EV landscape could look like in a few years' time but Toyota – the world’s biggest car manufacturer and a company that should know about such things – predicts there won’t be one single answer to the EV question.

It’s developing three different conventional battery types: Popularisation, Performance and High Performance.

The Popularisation battery uses lithium iron phosphate chemistry to increase range by 20 per cent compared to a current battery and will be 40 per cent cheaper to produce, with charging speeds of less than 30 minutes for a 10-80 per cent top-up.

The company’s Performance batteries are expected in 2026 using lithium-ion chemistry, they’ll be 20 per cent cheaper to produce than a current battery – like the one found in the bZ4X SUV – and will be capable of 10-80 per cent charge in less than 20 minutes.

High-performance batteries go one step further, cutting costs by a further 10 per cent compared to a Performance battery and allowing for a range of more than 620 miles, equal to the range of early solid-state batteries.

Further to this, Toyota’s chairman Akio Toyodo expects that electric cars will make up just 30 per cent of the global market share with combustion engines, hybrids and hydrogen fuel cells making up the rest of the mix. Toyoda cited the fact that 1 billion people on earth have no access to electricity as being a major obstacle to the extinction of petrol and diesel cars.  

Are solid-state batteries coming? 

Toyota expects solid-state batteries to be available as early as 2027 but you can expect these pioneering models to be expensive, it could be several years before the economies of scale open solid-state batteries up to the mass market.

Mercedes, meanwhile, has partnered with ProLogium, a Taiwan-based battery producer, and USA-based battery experts, Factorial, to produce solid-state batteries. Its product roadmap expects solid-state battery prototypes to hit the road in a couple of years with customer cars following a few years later.