When you think of electric car batteries, you think of lithium-ion batteries. They work well enough for now, but they won’t be adequate for much longer.

Volvo has announced its intention to sell only electric vehicles by 2030. Other car manufacturers likewise vow to move beyond internal combustion engines.

Their success depends on electric car batteries that recharge quickly and safely, enable cars to travel long distances on a charge, and not take up much space. In other words, it depends on new, emerging battery technology and innovative battery design.

Some problems with today’s lithium-ion batteries

Although lithium is plentiful enough, commercially viable concentrations occur in only a few places. Most lithium mines are located in Australia, the Andes, and North America. Attempts to develop American lithium mines have become mired in environmental disputes.

We now depend on lithium batteries to operate far more than electric vehicles. They power our electronic gadgets. They store electricity from intermittent renewable energy such as wind and solar. In addition, other industries besides batteries need lithium, including medicines for mental health. As demand for lithium batteries grows, fierce competition for lithium drives up its price for all applications.

Lithium batteries need more than just lithium. Competition for nickel and cobalt is greater than competition for lithium. And cobalt has the added problems of being highly toxic and coming mostly from the Democratic Republic of Congo. Congo is chronically wracked with civil war and human rights abuses in the cobalt mines. Innovative battery technology seeks to replace heavy metals.

Lithium-ion batteries use graphite in the anode. It adds weight and space to the battery. When used as electric car batteries, that added weight drains the battery faster for the same reason that added weight in an ordinary car reduces gas mileage. New battery design looks to eliminate excess weight.

The big trouble with lithium batteries: dendrites

Batteries consist of two electrodes, a separator between them, and an electrolyte. During charging, electrons travel through the electrolyte from the cathode (positive electrode) to the anode (negative electrode). Ideally, metal coming from the cathode should arrange itself in neat layers to pack the anode. Lithium ions do not behave in such an orderly fashion. Instead of packing into the anode, the lithium accumulates on it.

When that happens, dendrites can form on the anode. Dendrites are spiky little formations that can grow back toward the cathode. Like weeds pushing through pavement, they can puncture the separator. If dendrites reach the cathode, they create a short circuit. Dentrites constitute one of the main focuses of emerging battery technology.

Today’s lithium-ion batteries use a flammable liquid for an electrolyte. The short circuit can catch it on fire. The faster a battery charges, the more trouble dendrites can cause. Liquid electrolytes can also freeze. So they require expensive warming, cooling, and monitoring systems that add even more weight.

Graphite inhibits dendrite formation but also limit availability of lithium. In turn, that makes it impossible to develop a lithium-ion electric car battery using standard technology that can travel a thousand miles on a charge.

Both the liquid electrolyte and the graphite anode add weight to the battery. A pure lithium anode could in principle increase energy density enough to double the range of a car without increasing the weight or volume of the battery.

It will also form dendrites like crazy until someone can find a battery design to suppress them or even prevent them from forming. Nanotechnology is suggesting ways to redesign anodes to prevent dendrites.

The promise of solid-state electric car batteries

Michael Farraday invented the solid-state battery in the 1830s. In nearly 200 years, no one has been able to get them to work well enough. Either they operate only at very high temperatures or they can’t be recharged as many as 800 times and retain 80% capacity.

New electrolyte design can suppress dendrites. Adding a protein called fibroin, for example, can induce lithium to pack into the anode in neat layers. It will be possible to recharge such a battery thousands of times without significant formation of dendrites.

QuantumScape, which has been working on new battery technology for a decade, claims to have succeeded at making a solid-state battery that can operate at reasonable temperatures and still retain 85-90% capacity after 800 cycles.

It can recharge to 80% capacity in just 15 minutes. A 2-minute charge time is within reach, which is less time than it takes to fill a gas tank.

The company has added a gel catholyte within the cathode and developed a solid electrolyte with a ceramic separator that uses existing technology, which reduces manufacturing costs. This new battery design is manufactured without an anode. During charging, lithium forms the working anode.

The company has not released details of the separator design. Not all observers are persuaded that the anode-free design has yet completely solved the dendrite problem.  But Volkswagen has invested $300 million in QuantumScape’s technology and hopes to introduce the batteries into its higher-end products by 2024-2025. So, after decades of the promise of solid-state electric car batteries fading into vaporware, QuantumScape hopes to manufacture them at mass-market scale, and very soon.

A hybrid lithium battery

A company called SES has announced a new battery design with a pure-lithium anode. It says the new battery will almost double the energy density of lithium-ion batteries without producing conditions that can catch them on fire.

It’s not solid-state, though. The company created a new liquid electrolyte saturated with salt. It’s stable and safe. A third-party evaluator punctured a cell with a nail. That would cause a fire in any standard lithium-ion battery. With the solid lithium anode and salt electrolyte, it didn’t.

In its factory, SES uses artificial intelligence to monitor its batteries and look for defects, such as dendrites. It is looking for ways to make monitors that work in vehicles on the road. When such a monitor finds defects, two solutions exist.

One uses a special charging protocol that heats the anode with just the right electric current. It doesn’t reach a temperature that can melt the lithium, but it can move lithium atoms around enough to smooth out the anode and essentially eliminate the dendrite.

If for some reason that doesn’t work, the monitors at least identify which cells are likely to fail. Those cells can be replaced before they destroy the battery.

SES hopes to market its hybrid lithium battery by 2025. It’s partnering with such auto manufacturers as GM and Hyundai. Solid-state electric car batteries will probably become practical eventually, but few believe it will happen that soon. The hybrid battery could play an important role in the meantime.

Who says electric car batteries have to use lithium?

The last time I wrote about new battery technology, I cited work on sodium-ion and magnesium-ion solid-state batteries.

Before Sony marketed the first commercial lithium-ion battery in 1991, most battery research worked with sodium. Lithium (atomic number 3) is the lightest of all solids. Sodium (atomic number 11) is the third lightest.

With atomic number 4, beryllium is the second lightest metal. I found a patent for a beryllium battery from 1975, but nothing has come of it.

Sodium batteries

Sodium is more abundant than lithium and therefore less expensive. The two metals differ enough that it’s not possible simply to swap one metal for the other without redesigning the entire battery.

Problems include how easily electrolytes can deteriorate and reduce battery life. Pure sodium can also be as explosive and reactive as lithium. Unfortunately, sodium batteries with enough energy density to operate cars still typically include nickel.

But some labs and startups still work with sodium and have started to solve these problems.

California-based Natron builds sodium batteries, mostly for industrial backup power, using only materials available locally. Its batteries are not especially energy dense even compared to other sodium batteries, but used as electric car batteries, they charge quickly.

That becomes a significant advantage at times when the power grid is stretched thin. The batteries are also safer than lithium batteries both for electric vehicles and energy storage. Sodium batteries also work faster in cold weather.

Recently, the Chinese company CATL, one of the world’s largest manufacturers of lithium batteries, announced its intention to mix sodium and lithium cells in electric car batteries. In part, it’s a hedge against the rising scarcity of lithium. CATL, too, has developed a nickel-free cathode.

According to Shirley Meng, a battery researcher at the University of California at San Diego, the success of lithium has been the greatest barrier to development of sodium batteries. And although sodium is cheaper than lithium, sodium batteries are not yet cheaper than lithium batteries.

Sodium batteries’ cost advantages depend on scaling up production. And scaling up production depends on large companies such as CATL. Also, according to Meng, lithium alternatives—not only sodium but zinc and vanadium—offer the US a chance to build the battery industry it now lacks.

Sources:

Lithium-metal “hybrid” battery promises lighter, longer-range EVs by 2025 / Tim De Chant, Ars Technica. November 8, 2021
Sodium batteries may power your new electric car / Gregory Barber, Wired. November 8, 2021
The tricky challenge holding back electric cars / Stephen Ornes, PNAS. June 29, 2021
Will solid state batteries bring gas-competitive range, quicker charging to EVs? / Frank Marcus, MotorTrend. December 22, 2020