Solid-state batteries with lithium metal as anode material could significantly increase the range of electric vehicles.Andreas Croonenbroeck
The race for long-range solid-state batteries is gaining momentum. While the technical challenges of the batteries of the future still need to be overcome, these automakers are positioning themselves with the help of research and startups.
The king is dead, long live the king. But wait, we are not
there yet—at least not when it comes to batteries for electric vehicles. The
conventional lithium-ion battery has not yet reached the end of its lifecycle.
The proven technology still offers ample potential for further development.
Starting in the middle of the decade, Mercedes, in collaboration with its
partner Sila Nano, aims to introduce a significant advancement in lithium-ion
battery technology in the electric version of its G-Class SUV. These energy
cells are expected to achieve an energy density of more than 800 Wh/l, which is
20 to 40 percent higher than current lithium-ion batteries. Other major OEMs
are targeting similar values.
What Is a Solid-State Battery?
A solid-state battery, also known as a solid-electrolyte
battery, differs from conventional batteries like lithium-ion batteries in its
use of a solid electrolyte instead of a liquid or gel-like one.
Key Differences:
Electrolyte Material: The biggest difference between a solid-state battery and other battery types is the use of a solid electrolyte instead of a liquid or gel-like one. This can lead to higher safety and energy efficiency.
Safety: Solid-state batteries are considered safer than conventional lithium-ion batteries. The solid electrolyte is less flammable than the liquid electrolytes used in other batteries. Additionally, the risk of leaks is significantly reduced.
Energy Density: Solid-state batteries typically have a higher energy density than conventional batteries. This means they can store more energy in a smaller volume, potentially leading to smaller and lighter batteries for electric vehicles.
Operating Temperature: Solid-state batteries can operate over a wider temperature range, making them more suitable for extreme environments.
5. Charge Cycles and Lifespan: Solid-state batteries can offer a greater number of
charge cycles and a longer lifespan compared to traditional lithium-ion
batteries. Additionally, they can be charged significantly faster.
What Are the Advantages of Solid-State Batteries?
But the better is the enemy of the good. By the end of the
decade, Mercedes plans to integrate solid-state battery technology into its
vehicles. The advantage of these batteries lies in their significantly higher
energy density. To illustrate: A lithium-metal anode has approximately ten
times the specific energy of the graphite anode used in lithium-ion batteries.
"We expect solid-state batteries to achieve energy
densities of up to 1,200 Wh/l," states Mercedes. This promises
significantly greater range. But not only that. "With these performance
values, new applications for electrification become possible, such as
battery-electric flight or solutions for heavy-duty commercial vehicles,"
explains Peter Fintl, Head of Technology and Innovation at Capgemini
Engineering.
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The fact that solid-state batteries use inorganic, solid, or
ceramic electrolytes arranged in thin layers increases stability and safety.
These components are more resistant to heat and damage, making them less
flammable. However, solid-state batteries currently function best within a
temperature range of 50 to 80 degrees Celsius. This is not ideal for reliable
cold-start behavior at very low temperatures. Research is focused on overcoming
this hurdle. Once achieved, the advantages of solid-state batteries will
outweigh their challenges, significantly increasing vehicle range.
Polymer-Based Solid-State Batteries
As part of the Cell Platform Polymers Project (FB2-POLY),
researchers at the Landshut University of Applied Sciences, in collaboration
with the Helmholtz Institute Münster, the Helmholtz Institute Ulm, and the
Karlsruhe Institute of Technology (KIT), aim to develop new concepts for
high-performance and safe batteries using polymer-based solid electrolytes.
Landshut University is contributing to the development of a
lithium-free anode based on electrospinning technology. Here, the lithium anode
forms only during charging, using lithium from the cathode, and dissolves again
during discharge. According to researchers, using a lithium-free anode could
significantly reduce battery production costs since processing metallic lithium
requires complex procedures. From an application perspective, the Landshut team
is exploring the possibility of using lamination technology to assemble and
connect solid-state batteries with a polymer electrolyte. The goal is to
transition this process into mass production.
At the end of the project, researchers aim to provide
materials that will enable Germany to become a global leader in battery storage
technology. They are working closely with industry partners to develop
strategies that will be applied in a pilot manufacturing setting. The
researchers are also considering future industrial requirements right from the
start.
Nio Announces 150-kWh Battery Pack From Mass Production
According to media reports, Nio has introduced its first
mass-produced semi-solid-state battery pack as part of its battery-swapping
concept. Currently, the Chinese OEM offers vehicles with two battery options:
75 kWh and 100 kWh. Soon, a new 150-kWh battery option with an energy density
of 360 Wh/kg is expected to provide an extended range of up to 1,055 km.
Following its initial announcement in 2021, Nio has now
begun mass production of the semi-solid battery, developed by WeLion New Energy
Technology. This company also serves as the battery supplier. The exact market
release date for the new battery packs remains unclear.
Svolt Develops Sulfide-Based Electrolyte
Chinese company Svolt has assembled its own R&D team to
advance solid-state cell technology. Recently, it produced its first batch of
20Ah cells with a sulfide-based solid-state electrolyte, becoming the first
Chinese battery manufacturer to demonstrate this type of cell production.
Svolt identifies key challenges such as maintaining high
conductivity in the solid electrolyte, ensuring long-term stability at
interface contacts, and efficiently transferring lithium ions even at high
charge rates. The company claims that sulfide-based solid-state cells
outperform liquid-electrolyte cells in energy density, charging speed, safety,
cycle stability, and temperature resistance.
In abuse tests, such as a 200°C hot-box test and a nail
penetration test, Svolt’s 20Ah cells remained intact, whereas traditional
liquid-electrolyte cells typically suffer from thermal runaway under similar
conditions. Svolt plans to continue expanding its research activities in
solid-state batteries and new processing technologies to further develop the
foundation for mass production.
BMW Aims to Capture the Solid-State Battery Value Chain
Automakers now see solid-state batteries as an opportunity
to catch up with Asian competitors in lithium-ion battery production. BMW, for
example, leads the Alano research project, where the German automaker
collaborates with the Helmholtz Institute Ulm and other partners to develop
innovative EV battery concepts with lithium-metal anodes.
The ambitious goal is to develop a commercially viable
solid-state battery while also establishing an entire value chain—from material
selection and component manufacturing to cell production, battery scaling for
vehicles, and ultimately recycling. BMW has also partnered with Ford and Solid
Power to produce solid-state battery prototypes. These cells, boasting an
energy density of 390 Wh/kg and 930 Wh/l, can charge up to 80% in just 15
minutes. The first prototype vehicles equipped with these batteries are expected
to be on the road later this year.
What VW Is Planning with QuantumScape
In the race for pole position in solid-state batteries,
other automakers are not sitting idle. The Volkswagen Group has been the
largest shareholder in QuantumScape, a Stanford University startup, for four
years now, and new results have recently emerged. Co-founder and CEO Jagdeep
Singh announced at Bloomberg’s Green Summit that his company has successfully
developed a 16-layer solid-state cell that retains over 80 percent capacity
even after 500 fast-charging cycles of 15 minutes each. The key advancement is
not only the six additional layers compared to the cell the startup introduced
in November 2021 but also the fact that the cells now function at a temperature
of 25 degrees Celsius and under air pressure no higher than 3.4 bar.
QuantumScape is prioritizing flexibility in its solid-state
batteries. "Our architecture is cathode-independent, meaning we can
transition from nickel to iron," Singh explained. The key breakthrough
is the ability to pair an iron-based cathode with a lithium-iron anode, which
can result in a 50 percent increase in energy density. This flexibility is
particularly advantageous given ongoing supply chain challenges.
"Regarding cathodes, we face the same supply chain limitations as everyone
else," Singh acknowledged.
When Will Toyota Introduce Solid-State Batteries in
Passenger Cars?
Toyota is also jumping on the solid-state battery bandwagon,
working alongside Panasonic on these next-generation batteries. This project is
being handled by their joint venture, Prime Planet Energy & Solutions Inc.
The key to their energy storage technology lies in the electrolyte, which in
Toyota and Panasonic's case is a phosphorus-sulfur compound. The Japanese
automaker plans to release its first vehicle with a solid-state battery in
2025, but it won’t be a fully electric vehicle (BEV)—instead, it will be a
hybrid model.
The reasoning behind this seemingly cautious decision is
cost. Solid-state batteries are currently significantly more expensive than
lithium-ion batteries, which would drive up the price of such a vehicle. Toyota
is determined to avoid this. Over time, however, solid-state batteries are
expected to become cheaper than today’s lithium-ion cells. Additionally, Toyota
views using the technology in a hybrid as a stress test. This will help assess
factors such as frequent charge cycles and the impact of operating temperature
on the battery.
If these batteries pass Toyota’s rigorous testing, they are
expected to go into full-scale production by 2028. Toyota is already working
intensively on mass production of solid-state batteries, as the company has
announced. The performance data of these batteries is impressive and could
solve some of the key challenges in e-mobility: up to 1,200 kilometers (746
miles) of range with a charging time of just 10 minutes to reach 80% capacity.
In the long term, Toyota envisions a potential range of 1,500 kilometers (932
miles).
Mercedes Collaborates with Multiple Solid-State Startups
The U.S. startup Factorial Energy is attracting automakers
like moths to a flame. In addition to Stellantis and Hyundai, Mercedes is also
investing in the Massachusetts-based company. According to Factorial, its
engineers have solved the temperature problem, allowing the cells to operate at
room temperature.
Expectations are high: "With Factorial as a
new partner at our side, we are taking research and development in the
promising field of solid-state batteries to the next level. That’s why we are
investing a high double-digit million-dollar sum in Factorial,"
explained Mercedes CTO Markus Schäfer.
What Electrolytes Are Used in Solid-State Batteries?
Solid-state batteries use various types of solid
electrolytes instead of the conventional liquid or gel-based electrolytes.
Below is an overview of the most common electrolyte types:
Polymer Electrolytes: Widely used due to their flexibility and safety. They consist of long polymer chains that can conduct lithium ions.
Glass-Ceramic Electrolytes: Often contain lithium and other elements and are known for their high conductivity.
Oxide-Ceramic Electrolytes: These can achieve high ion conductivities and are thermally stable, but they often face challenges in manufacturing and interfacial stability.
Sulfide-Based Electrolytes: Examples include lithium-phosphorus-sulfide (LPS) and thio-LISICON. They offer high lithium-ion conductivity but are chemically unstable when exposed to air or water.
However, Mercedes wouldn't be Mercedes if its solid-state
battery strategy relied on just one pillar. The second key player in its bid
for the future of battery technology is the Taiwanese company ProLogium, with
whom the German automaker has been collaborating for some time. Mercedes is
investing heavily in ProLogium’s research efforts and has even secured a seat
on the company's board. The move makes sense for Mercedes, as ProLogium is,
according to the company, the first battery manufacturer in the world to
mass-produce solid-state lithium-ceramic batteries. The plan is for ProLogium
to open a gigafactory near Taipei by the end of this year, with the first
solid-state battery prototypes expected to be tested in Mercedes vehicles in
the coming years.
GM Invests Billions in New Battery Technology
The days when GM sat back and watched competitors while
relying on its dominance in the North American market are over. The American
automaker is actively pushing into the solid-state battery sector. GM CEO Mary
Barra has allocated $7 billion to establish a supply chain for next-generation
batteries, including solid-state technology. A key partnership in this strategy
is with Posco Chemicals, which will build a new factory in Quebec to produce
cathode-active materials for GM’s Ultium battery cells.
However, even in the solid-state battery sector, the world
remains small. Recently, Posco Chemicals has also invested in ProLogium,
raising questions about how the competing interests of OEMs will be balanced.
Fundamentally, Hyundai, Stellantis, GM, and Mercedes share the goal of making
solid-state battery technology commercially viable. However, that is where
their shared interests end. When it comes to competitive advantages and market
dominance, the current alliance could quickly fracture, leading to fierce
competition as each automaker fights for its own strategic position in the
industry.
How Much Does a Solid-State Battery Cost?
The exact price of a solid-state battery can vary
significantly and depends on several factors, including the specific
technology, production volume, and application areas. Since solid-state
batteries are still in the development and early production phases, their cost
per kilowatt-hour (kWh) is generally higher than that of conventional
lithium-ion batteries.
Currently, the cost of solid-state batteries is estimated to
be around $200 to $400 per kWh. In comparison, the cost of lithium-ion
batteries has dropped significantly in recent years and currently ranges
between $100 and $150 per kWh.
However, these costs are only preliminary, and prices for
solid-state batteries are expected to decrease significantly in the coming
years as the technology matures and production scales up. In the long run,
solid-state batteries could even become more cost-effective than lithium-ion
batteries, especially when considering their higher energy density and longer
lifespan.
