Electric vehicle (EV) sales milestones made headlines in 2023. The U.S. experienced a 50% increase in EV sales in 2023, with over 1.4 million sold. Electrification is shifting from luxury to mainstream — a culmination of engineering efforts. The automotive industry and EV supply chains are becoming better integrated. And lithium-ion (Li-ion) batteries are the lifeblood that is driving the decarbonization of modern transportation.

However, their imperfections are also leading experts to explore alternatives to make up for Li-ion’s shortcomings. Among the options are solid-state batteries.

The number of Li-ion manufacturers in North America suggests a capacity of 10 million new cars annually, with packs ranging from 80 kWh to 100 kWh each. The data shows that Li-ion is well adapted from small consumer electronics to large applications. It is everywhere, so how competitive can up-and-coming options, like solid-state batteries, genuinely be?

How common are Li-ion batteries?

Li-ion’s popularity has come with supply chain hiccups and material shortages, causing long waitlists for buyers. While there are some alternative types of batteries in the works, nothing else has reached an ideal balance of performance, environmental impact and price.

Li-ion is the most commercial-friendly option out there. However, solid-state batteries are promising because they eliminate most of Li-ion’s problems, boasting cells with 300 kWh capacities or higher.

What are Li-ion’s technical limitations?

Li-ion’s popularity has come with supply chain hiccups and material shortages, causing long waitlists for buyers.

The battery’s flammability is perhaps the most infamous aspect of Li-ion’s ill reputation — the electrolyte’s solvents are highly flammable. Once ignited, a cell fire will quickly include the rest of the battery, a condition known as thermal runaway. It is a rare phenomenon without enough occurrence to endanger drivers. However, the publicity is off-putting to buyers and it delays further EV adoption. Li-ion’s list of other faults includes:

• Poor temperature regulation and thermal runaway
• High weight, which reduces vehicle range
• Environmentally destructive raw materials extraction
• Hard-to-recycle units and lack of circularity
• Fast degradation

Why do these limitations exist in the first place? Most of it boils down to the battery’s recipe. Nickel, cobalt, lithium and copper are expensive, hard to source and hefty. The electrolyte is volatile and requires optimization in entropy and boiling or freezing points. The competitiveness of sourcing these metals requires more batteries to become market-viable. Otherwise, Li-ion availability, and all the technologies relying on it, stall.

There are some advantages that Li-ion has that will need to translate to solid-state and other battery forms, for their development to be a success. Most importantly is Li-ion’s mature development state. These batteries have established transportation regulations and supply chain infrastructure. Advocacy led to regulatory action, like the Inflation Reduction Act, which made the technology cost-effective with incentives for businesses and individuals. This has yet to happen with other battery constructions.

How are solid-state batteries a viable alternative?

Researchers are trying to diversify the battery market to lessen production issues and assembly delays. These are several contenders:

• Lithium-metal: Solid lithium for the anode to make the battery more lightweight and extend charging cycles.
• Sodium-ion: Sodium in a liquid electrolyte lowers costs by removing nickel and cobalt for increased durability and Coulombic efficiency.
• Aqueous magnesium: Magnesium as an anode to extend range, charging speeds and material recyclability.
• Metal-air: Oxygen as a cathode feedstock to boost energy efficiency and density.

Solid-state batteries strive to take lithium’s model and make every aspect more powerful. Researchers claim solid-state will have:

• Higher density
• Improved conductivity
• Increased safety
• Longer life spans
• Extended charging cycles
• Faster recharge speeds

They achieve this by reducing the number of materials and choosing more stable and cheaper substitutions for metals like cobalt.

Notably, solid-state batteries eliminate byproducts of aging in Li-ion compositions, like lithium dendrite formation. This reduces shortages and reactive maintenance. Additionally, there is no need for preventive leakage casing because the electrolyte is solid.

Replacing weighty graphite anodes with lithium-metal also enhances EV performance, improving its range from optimized cell volume to density. Solids are more expedient at charging the anode base layer than the intercalation process of Li-ion electrolytes, slashing charge times. The construction also keeps lithium from transforming into a solid electrolyte interphase (SEI) layer, which takes necessary metals away from future cycles.

Experiments are appearing in numerous research programs. The first is in shape. Li-ion is heavy and bulky, reducing acceleration and handling potential. Designers challenge traditional cylindrical, coin-cell and prismatic Li-ion battery structures with solid-state pouch cell layouts. They maintained 80% capacity after 6,000 charges in high temperature variances, giving solid-state EVs an edge from an electrical and performance point of view.

Anodeless constructions are another imaginative solution from engineers. They are compact and lightweight, meaning energy capacity is easily expandable by placing more batteries into a car. This can happen without compromising performance metrics reliant upon weight, like range and energy consumption. Reducing the need for anode components saves money and raw materials for producers. At the same time, it redirects more resources to creating greener, more effective cathode and electrolyte combinations.

A composite of polymers and ceramics may be the most viable setup. It balances conductivity for managed capacity at intense discharging rates with cheaper, robust materials. Semi-solids are another consideration for scaling, though they may not produce the range and life spans of solids. However, they still permit fast travel of ions between the anode and cathode. These could buy time as solids become easier to produce and price.

Future EV expansion

Solid-state has a clear advantage over Li-ion’s pitfalls. With boosted range and safety, solid-state will be lithium’s most aggressive competitor technology in the near future soon. This could be a further boon to EV proliferation, if buyers are convinced cars will charge quickly and provide enhanced range.

The current state of these batteries proves they are almost ready for commercial distribution. Researchers must only overcome several roadblocks in production before coming to market, including dendrite formation on anodes, heightened cooling systems and, perhaps most importantly, the hefty price tag.

Several big names, like Toyota and Honda, are formulating partnerships to get solid-state battery vehicles to customers by as early as 2027. If marketability truly relies on affordability, then good news, as automakers are working to bring solid state battery vehicles to market with a relatively inexpensive $30,000 price tag.

The next several years of research and development will reveal if this goal is fact or fiction

About the author

Ellie Gabel is a science writer specializing in astronomy and environmental science and is the Associate Editor of Revolutionized. Ellie's love of science stems from reading Richard Dawkins books and her favorite science magazines as a child, where she fell in love with the experiments included in each edition.