Solid-state batteries (ASSBs) promising longer driving range, faster charging, and safer chemistry are almost here—but producing them on the scale needed to power millions of EVs won’t be easy.
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.”