These advantages are fuelling intense efforts around the world to put ASSBs in vehicles by mid-decade. AME expects the share of new batteries (primarily ASSB) in global battery production will rise to 12% in 2030, from just 1% in 2025.

Billions of dollars have already been invested in the technology—with much of it being poured into start-ups. Volkswagen has funnelled more than US$300m into QuantumScape. BMW and Ford are betting US$130m on Solid Power. General Motors has invested in SES AI Corporation. Factorial Energy raised US$200m at the end of 2021, led by Mercedes-Benz and Stellantis.

Global sales of EVs are expected to reach 10.5m this year, after more than doubling in 2021 to 6.6m. Despite this growth, the lithium-ion batteries powering all those electric motors still lags behind their internal combustion counterparts.

Lithium-ion powered EVs deliver a median range of 234 miles (377 km) on a single charge, according to estimates from the US EPA for 2021 models. This is compared to 403 miles (649 km) for gas-powered vehicles before they require a fill-up.

To win over customers, EVs need to step up their game and this is where ASSBs come in. ASSBs could extend an EV’s range significantly given their higher energy density—which is how much energy the battery can store for a given volume. QuantumScape expects a range between 375-400 miles (604-644 km), while Solid Power thinks it could stretch above 500 miles (805 km). 

Solid state technology uses solid material instead of liquid electrolytes to ferry electric current in a bid to improve EV performance. The tighter-packed molecules in a solid electrolyte can pack more energy in the same amount of space.

Ditching the liquid also lowers the risk of a battery fire as solid electrolytes are largely non-flammable. This eliminates the need for costly thermal management systems found in liquid-electrolyte batteries. That means battery packs could be denser as safety systems require less space—improving energy density, as well as safety.

Fires are a rare but notable problem in lithium-ion batteries. In 2021, General Motors expanded an earlier recall of its Chevrolet Bolt EVs due to battery-fire concerns. The recall is expected to cost nearly US$2bn and cover around 142k cars.

The solid-state approach opens new options for higher capacity battery electrodes, such as lithium metal and silicon, which are unstable or unsafe when combined with a liquid electrolyte.

Big Potential Spurs Big Investments

Battery-focused firms are racing to reach the market first. QuantumScape claims that you will be able to buy a Volkswagen with its solid-state batteries soon as 2024.

The California-based company expects to deliver early prototype cells by the end of this year and build a pre-production line before the end of 2023. It expects to deliver ASSBs from its first gigafactory to Volkswagen for integration in a test car by 2024 or 2025.

Solid Power’s solid-state batteries could improve the energy density of lithium-ion batteries by about half, according to CEO Doug Campbell. That means an EV that used to go 350 miles (563 km) could go above 500 miles (805 km) before needing a recharge.

In June 2022, the company said it had installed a solid-state pilot production line in Colorado and would deliver solid-state cells to BMW and Ford for testing at the end of the year.

Solid Power plans to ramp up to produce enough material for 800k cars annually by 2028. Instead of making or selling full batteries in the future, the company plans to provide the solid electrolyte material and its proprietary cell designs to other battery makers.

Factorial Energy aims to introduce its “first competitive solid-state battery technology” by 2026. The Massachusetts-based company says its technology can extend an EV’s driving range by 20% to 50%. It has received investments from Hyundai, Kia, Stellantis and Mercedes-Benz.

Major auto players are getting in on the action too. Toyota plans to launch its first EV powered by solid-state batteries in 2025. In 2021, the world’s largest automaker announced plans to pour US$13.6n into battery development and production by 2030, which includes solid-state batteries.

The company’s first ASSB batteries would be deployed in hybrid cars, which use smaller battery packs and require less charging. Last year, Toyota gave the world got its first look at a solid-state-powered EVs—unveiling its LQ concept car at the Tokyo Olympics.

Nissan has set itself a longer timeline, with a plan to begin large-scale ASSB production by 2028. That’s not to say the company is not ambitious. It plans to build ASSBs with twice the energy-density of the current lithium-ion batteries, and one-third the charge time. A pilot production line is expected to come online in Japan in 2024.

Nissan released the first lithium-ion battery powered vehicle in 1998. The Nissan, Renault, and Mitsubishi alliance is also targeting commercial manufacturing of ASSBs by 2028. The alliance has announced a combined investment of EUR23bn (US$23.4bn) in EVs.

Samsung introduced a solid-state battery prototype in 2020. The prototype battery can drive an EV up to 800km on a single charge and has a lifespan of more than 1,000 charge cycles. The company has begun building a pilot production line in South Korea, with the first cells expected in early 2023.

Different Paths: Technical Differentiators

The specific battery chemistry of solid-state designs varies from company to company. Nissan, which has been developing solid-state technology for a decade, hasn’t settled yet on a specific battery chemistry, and is considering using different chemistries for different cars.

The company is reportedly focusing on sulfide-based solid electrolyte that includes a “hopping” mechanism, which boosts the speed and ease at which ions move between the cathode and anode. Solid Power will also use a sulfide-based solid electrolyte, while QuantumScape will use a ceramic electrolyte. Both promise to have high conductivity and lithium metal stability. 

QuantumScape’s solid-state battery can charge from 10% to 80% in less than 15 minutes. Solid Power has claimed 10% to 90% in the same time. That’s dramatically less time than current lithium-ion batteries, which typically take 60 minutes to charge from 10% to 80%. But it’s still longer than conventional vehicles, which takes around 5-7 minutes to refill.

QuantumScape’s batteries have an “anode-free” configuration. That means all the lithium remains initially within the battery’s cathode until, upon the first charge, it migrates across the electrolyte to the other end of the battery, electromagnetically making an anode and ensuring equal distribution of the lithium ions. The anode-free lithium metal architecture is touted to increase energy density by 50-80%.

Solid Power plans to use over 50% active silicon in its first solid-cell anode. Silicon has 10 times the energy density as the graphite anodes used today and offers more stability than lithium. It also plans to use lithium-metal.

Are Solid State Batteries More Environmentally Friendly?

Solid-state NCM-811 batteries have the potential to reduce an EV’s carbon footprint by 39%, compared to current NCM lithium-ion batteries, according to research released last month by Brussels-based Transport & Environment (T&E). This scenario is based upon the use of sustainably sourced technology and materials.

In a less sustainable scenario, a 24% reduction is still expected, as a solid-state battery can store more energy with less materials. Solid state batteries could require up to 35% more lithium than the current lithium-ion technology but far less graphite and cobalt. 

Producing lithium-ion batteries takes a lot of energy, which underscores the need for a more sustainable supply chain. Producing 1kWh of lithium-ion batteries takes about 50-60kWh of energy. Increased energy efficiency, the regionalization of supply chains and higher use of renewable energy all have a role to play.

Unlike lead acid batteries, which are 99.5% recycled, less than 20% of lithium-ion batteries are recycled today. Chemistry plays a key role in this divergence: lead acid batteries use a water-based electrolyte, making them safe to dissemble, whereas lithium-ion batteries use organic liquid electrolytes that are flammable.

Recycling solid-state batteries will be intrinsically safer as they're made entirely of nonflammable components. Growing battery demand is already driving a build out of recycling capability. Hydrovolt, the joint venture between Northvolt and Norsk Hydro, opened Europe’s largest EV battery recycling plant in May 2022. The facility can currently handle about 25k EV batteries a year.  

Reality Check: Key Obstacles

Achieving scale will be the biggest challenge. Taking the technology from the lab to large-scale manufacturing will require both engineering innovation and massive investment—not to mention time.

Start-ups, are of course, optimistic. Factorial says its technology can be easily integrated and adapted into existing lithium-ion manufacturing methods. Solid Power says its production line has been purposed-built to mimic established manufacturing to “reduce commercial risk”.

While technological readiness continues to improve, striking the right balance is a formidable task. For example, inorganic materials, like the sulfides that Solid Power uses, can be difficult to move during manufacturing due to brittleness when produced in thin layers, according to Lei Cheng, a chemist in the materials division at Argonne National Laboratory.

Inorganic materials have gained in popularity due to their higher conductivities compared to organic polymers, which are easier to manufacture.  

Another concern about solid batteries is how well they can withstand degradation over time, especially against dendrites—needle-like structures lithium often forms within batteries. They grow like roots and pierce the barrier separating the anode and cathode, causing the battery to short or even catch fire. QuantumScape is developing its batteries with a ceramic electrolyte, partly because the material is less susceptible to dendrite formation.

Solid-state batteries will need to be cost competitive to compete. The battery pack is the single most expensive part of an EV, accounting for about 30% of the total cost to consumers. Currently, the cost of solid electrolytes is higher than their liquid counterparts due to immature supply chains and a lack of scalable synthesis methods, according to researchers from the University of California San Diego.

However, most ASSB makers expect the technology to lower the cost of EVs by reducing raw material and pack system costs. Nissan says that its battery packs could cost as little as US$75/kwh by 2028, with a long-term goal of US$65/kwh. This is about half of the average cost of lithium-ion batteries in 2021 (US$132/kwh).

Meanwhile, Solid Power expects a 15-35% cost advantage over existing lithium-ion at the pack level. QuantumScape expects its ‘anode-free’ design to lower costs by eliminating material and manufacturing costs.

The massive investment in existing lithium-ion battery production could present another hurdle for mass-market proliferation of solid-state batteries. General Motors will spend more than US$35bn on EV development over the next three years, much of it on the company’s Ultium lithium-ion batteries.

Despite its solid-state goals, Nissan last year announced it would spend US$17.6bn over the next five years on lithium-ion battery development.

“There is going to be a phase of co-existence,” QuantumScape’s CMO Asim Hussain says. “Even if we scale to where we expect to with our plant, that’s still a small fraction of a maker like VW’s EV demand for batteries.”