Pros And Cons Of Solid-State Batteries: Are Solid-State Batteries The Savior of The EV? (2024)

For several years now, solid-state batteries have been touted as the next big step forward for electric vehicles because the consensus is that they'll double EV range. You'd think automakers and battery suppliers would invest as much as possible in this technology, but reports are extremely conflicting on whether they're even viable. In January 2024, scientists from Harvard University developed a new solid-state battery that can be recharged in 10 minutes without having an impact on the lifespan. As we know, EV batteries tend to degrade over time, which is one of the main EV drawbacks.

But in April 2024, CATL's (Contemporary Amperex Technology Company Limited) founder and CEO said solid-state batteries were unsafe and that they're not the fix-all solution everyone is hoping for. Dr. Robin Zeng is at the helm of the largest battery maker on earth and watched his company's engineers toil away for ten years without making any meaningful progress, so he's definitely what we might call qualified to pass comment.

Both sources are dependable and know what they're talking about, so which is it? Are solid-state batteries the next Model T moment, or will the concept flop harder than the GM EV1? To find out, we did a deep dive into the technology to discover the pros and cons to hopefully reveal a meaningful conclusion. But before we get to that, it's worth explaining what solid-state batteries actually are.

The Basic Design Of A Solid-State Battery

According to NewScientist, the key word here is solid. Most electronic devices, such as cars, phones, tablets, and laptops, use a lithium-ion battery. In this battery, you'll find a liquid electrolyte with ions flowing through it. The ions flow in one direction when charging and in the other while discharging. The general idea when it comes to solid-state batteries is to replace said liquid with a solid. That's the most basic explanation, and it sounds quite easy, right? It's a little more complex than that because solid-state batteries technically don't have to rely on lithium, which is a filthy element to mine. A solid-state battery could make use of sulfide or ceramics, though it has to be said that most solid-state batteries currently under development still rely heavily on carbon, titanate, phosphates, and metallic lithium. Metallic lithium is used for the anode and either oxides or sulfides for the cathode.

Solid-State Batteries Are Not A New Concept

Michael Faraday first discovered solid electrolytes in the 1830s but did nothing with the research. In 1986, Keiichi Kanehori made a thin-film solid-state battery, but it couldn't power anything larger than a watch, so the idea was shelved. The real father of the solid-state battery is John Goodenough, who also happens to be the father of the lithium-ion battery. Goodenough died in 2023, aged 100. He dedicated most of his life to battery research, and in 2017, he introduced what was arguably the world's first viable solid-state battery.

From 2018 onward, several companies that specialize in the technology were formed. Examples include Solid Power, Quantumscape, and Marata Manufacturing.

The Pros Of Solid-State Batteries

Before we get started, it's worth noting that not all the positive attributes of solid-state batteries have been scientifically proven, and some are still in the theoretical phase. The standard scientific method (or empirical method) requires a theory, systematic observation, measurement, and experiment, and the formulation, testing, and modification of the original hypotheses.

Volkswagen, which is part of a joint venture with Quantumscape, took delivery of solid-state battery prototypes in 2023. The resulting battery pack was not fitted to a car; instead, VW's in-house battery unit, PowerCo, put the pack through several tests. After 1,000 charging cycles (just over 310,000 miles), the pack had only lost five percent of its storage capacity, which gives us a nice segue into our first pro.

Solid-State Batteries Have A Longer Lifespan

As mentioned earlier, VW and Quantumscape's solid-state battery pack only lost five percent of its capacity after 1,000 charging cycles. The current acceptable standard is a 20% loss after 700 charging cycles. These figures by themselves are meaningless, so let's use a real VW product to demonstrate them.

The Volkswagen ID.4 in Pro, Pro S, and Pro S trims can reach 291 miles on a full charge. Applying the current standard, 700 charges would result in 203,700 miles of driving. If we apply the 20% loss, the battery pack would only be good for 233 miles. If we apply the solid-state technology, 1,000 charges would be a distance of 291,000. After those charges, the loss would only be five percent, which means this hypothetical battery pack would still be good for 277 miles.

According to the latest research conducted by The Zebra, Americans keep their cars for eight years or around 200,000 miles. A traditional lithium-ion battery only gets you just above that threshold, while a solid-state battery will theoretically get you way beyond that.

Solid-State Batteries Are More Energy Dense

According to a study published by ScienceDirect (Are Solid-State Batteries More Environmentally Friendly Compared To Traditional Batteries?), current lithium-ion battery technology has reached its peak when it comes to energy density. This density is basically the amount of energy you get per pound. The upper limit for what we now consider traditional batteries is 350 Wh per 2.2 lbs (1 Kg).

Solid-state batteries can provide up to 500 Wh per 2.2 lbs. That's a 30% increase in range using the same amount of weight. Once again, we can put these figures into context by using a typical EV as an example.

The Tesla Model Y Long Range's battery pack weighs 1,700 lbs, which enables it to travel 310 miles between recharges. If Tesla replaced the current battery with a solid-state battery that weighs the same, the vehicle would gain 93 miles of range, putting it higher on the list of EVs with the longest electric range. Even more importantly, even after a lifetime of use (200,000 miles), a solid-state Model Y would theoretically have more remaining range than the current car when brand new.

Manufacturers Can Use Smaller Batteries

Using solid-state technology to build batteries that weigh the same would be a counterproductive move, however. The average American only commutes 42 miles per day, so a range between 250 and 300 miles is perfectly adequate. It's the same old range vs. recharge debate, which basically boils down to people not understanding the concept that you don't need as much range as possible. Having a house with a Level 2 charger is the ultimate solution, as it ends the EV ownership nightmare.

There's a good chance automakers will use solid-state technology to decrease the size and weight of electric vehicles. Weight is one of the biggest enemies of all cars. A heavy car requires more energy to move, and it has more rolling resistance, which results in tires running down faster. But removing weight from an EV is not just beneficial to the owner, but to the general public, too.

Less Weight Means Safer Roads For Everyone

The GMC Hummer EV is the poster child for a problem all electric vehicles suffer from. It uses a 205-kWh battery pack, which is roughly twice the size of the industry standard. Thanks to that massive battery pack, it weighs more than 9,000 lbs. Couple that with a 0-60 mph time of 3.5 seconds, and you have a sizable block of metal that can cause a decent amount of devastation in less than four seconds. We're not the only ones concerned about weight, however.

The Insurance Institute for Highway Safety (IIHS) started updating its crash testing systems for heavy EV trucks, including the Hummer, the Ford F-150 Lightning, and the Rivian R1T. The IIHS announced these updates in December 2022, and by March 2023, it was calling for lower speed limits because electric vehicles are too heavy.

While the Rivian R1T is officially the safest electric truck you can buy, the same can't be said for whatever car it crashes into. The 2024 Kia Telluride is one of only five midsize SUVs to receive a Top Safety Pick + from the IIHS. That makes it one of the safest family SUVs you can buy, but imagine what would happen if it was involved in a head-on collision with the 7,000-lb R1T. The Kia weighs 5,000 lbs, which makes the Rivian nearly a Mazda Miata heavier than the three-row SUV with a 3.8-liter V6. There's no safety system that can beat basic physics.

Solid-State Batteries Recharge Faster

After more than a decade of progress, the average charging time is still roughly 20 to 40 minutes. We know EV evangelists will say you can use that time to grab some lunch and stretch your legs, but that's just not how people travel. That argument also only works if you assume that you'll want to eat every 300 miles. Most people traveling long distances just want to get it done with minimal hassle, especially if that trip is for work and they're traveling alone.

As mentioned at the start of this article, Harvard scientists have already developed a solid-state battery that can charge within 10 minutes. That's a lot more palatable and much closer than the five minutes it takes to refuel an ICE car. In this scenario, we agree that it's good to get out of the car and stretch your legs for a bit. If you need two recharges in a day, that's only 20 minutes lost. With current battery tech, you'll be stationary for at least 40 minutes. It's not just Harvard scientists that have made that claim either, as Toyota's Gen 1 solid-state batteries are touted to charge at the same rate when they first arrive in 2027-2028.

Solid-State Batteries Are Possibly Kinder To The Environment

Transport & Environment, a company that specializes in raw material lifecycle analysis, found that solid-state batteries can reduce the carbon footprint of an electric car by 39%. As most people should know by now, there's no such thing as a zero-emissions car. As soon as the first heavy machinery starts to dig into the ground, an EV starts emitting emissions. A smaller pack obviously requires less raw material, but the saving is more on the mining side. A solid-state battery will require 35% more lithium but less graphite and cobalt.

Unfortunately, there are some caveats worth knowing about, but we'll cover them in the cons section.

Solid-State Batteries Are Safer

The liquid electrolytes we referred to earlier are flammable and the main cause of thermal runaway. EV fires also happen to be one of the main go-to arguments by EV naysayers, who are as annoying as the evangelists. In a solid state, these electrolytes are not flammable and can withstand higher temperatures. So, even though there's no research that empirically states that EVs are more prone to catching fire than ICE cars, solid-state batteries should at least give electric vehicles a better reputation. Unfortunately, this is another pro that comes with a caveat.

The Cons Of Solid-State Batteries

Looking at the above pros, you're probably wondering why solid-state batteries aren't already equipped in every car out there. A Mustang Mach-E Rally with double the range sounds like a good day out, and Lucid could theoretically launch an Air with more than 1,000 miles of range, obliterating range anxiety forever. But as is the case with all new technology, solid-state batteries are having teething problems. Unfortunately, these teething problems are quite serious, leading to some automakers not even bothering or having to delay its introduction to 2030 at the earliest. The biggest cons at this stage are:

Scientists Don't Understand A Solid-State Phenomenon

One of the main reasons for solid-state delay is a phenomenon called "electric double layer" (EDL). As explained by Science Daily, it's "microscopic dispersions of one kind of particle in another substance." For those of us who don't speak science, there's electrical resistance between the positive electrode and the solid electrolyte, made worse when exposed to air. Scientists don't understand what's behind it, and even once they do, they still need to find a solution.

Delaying the introduction of solid-state batteries could have dire consequences for the technology. It's not the only alternative out there, with others including lithium-sulfur, cobalt-free batteries, sodium-ion, and iron-air batteries, all of which are eager to become the go-to solution. Solid-state also has to compete with alternatives that will keep combustion alive, like synthetic fuel.

The Technology Costs Too Much

Like most new technology, it takes time for costs to come down. We're more than a decade into traditional BEV technology, and price parity is still years away. For solid-state batteries to be affordable, production has to be ramped up drastically. That's not going to happen anytime soon, as stated by Toyota. Its first batch of vehicles with solid-state technology will only consist of "several tens of thousands of vehicles." That may sound like a lot, but Toyota made more than 11 million cars last year. Compared to that figure, tens of thousands is a small percentage.

These Batteries Can't Operate In The Cold Or Under Pressure

Traditional lithium-ion batteries don't operate optimally in cold weather, but solid-state batteries add another layer of complexity. Automakers currently use thermal management systems to keep battery packs at optimal operating temperature. Using these same systems in a solid-state system is not possible because the components have to be stored under immense pressure to keep dendrites from forming. The required pressure is more than 250 MPa. That's MegaPascal, and it's one of the best measurement systems ever invented. One MegaPascal is the downward pressure of one million banknotes. We don't know if that's a million Washingtons or a million Benjamins. Either way, the pressure inside a solid-state battery is equivalent to having 250 million banknotes stacked on your chest.

Pesky Dendrite Growth

As you may have learned by now, solid lithium is a very important part of a solid-state battery. Unfortunately, lithium in this state tends to grow dendrites. It's a non-uniform growth that can head in any direction, and it's sharp enough to puncture other parts of the battery, which is not ideal if you've got 250 million bucks of pressure to deal with. The best way to illustrate a dendrite is by using the most famous example, which is crystals. Look at the crystal formation below and imagine how much damage it can do to the inside of a battery pack.

The same Harvard scientists we referenced earlier claim their solid-state battery prototype is more resistant to these dendrites, utilizing micron-sized silicon particles in areas where ions attach during charging. But scaling that up to the level needed for the entire automotive industry to go solid-state is another challenge altogether.

Solid-State Batteries Are Only Environmentally-Friendly In The Right Conditions

Earlier we referred to Transport & Environment's study, stating that solid-state batteries can reduce the carbon footprint of an EV by 39%. That will only happen if certain governments can agree on a set of regulations that will clean up the production of lithium. There are newer models of extraction, like geothermal wells. This method has a much lower environmental impact, but China is the world's largest producer of lithium, and it already has a massive hard rock mine infrastructure in place.

The European Union also wants to implement a system to source lithium sustainably, but, once again, the EU has no control over China. These ideas are all well and good, but worth absolutely nothing unless they can convince China to completely change its mining infrastructure.

Solid-State Batteries Are Not As Safe As Originally Thought

CATL's CEO made waves when he stated that solid-state batteries are impractical and unsafe. According to Dr. Robin Zeng, also known as the Battery King, solid-state batteries have problems with pressurization, which also presents a danger when charging, as batteries expand when you feed them. And the engineers can't get around the pressure problem because of the dendrites we mentioned above.

And while these batteries may not catch fire, they arguably pose a bigger threat to drivers and passengers. If the battery is punctured in the event of an accident, the contents will react with oxygen, creating Lithium Hydroxide, which is toxic to humans. Basically, you'll be hanging upside down in a bubble of toxic fumes, and emergency responders won't be able to get to you because of that.

Conclusion: Solid-State Batteries' Savior Status Is In Doubt

The list of pros is undoubtedly impressive, but we have to remember that most of them are theoretical. And what little evidence we have was done in a lab, and not out in the real world. The introduction of the technology constantly being delayed is also concerning. Between now and 2030, a lot can happen. There are massive strides being made in other battery technologies, and that's before you even factor in political changes that might turn the entire EV segment on its head.

Our biggest concern is the obstacles the technology still needs to overcome. Scientists literally don't know why solid-state batteries do certain things, which means a viable solution is far from being ready. Secondly, the pressure issue is big. Lowering the pressure opens up a massive problem, and increasing it leads to more. It's the ultimate catch-22 problem.

Would we write it off completely? Not quite yet, because people have come up with some amazing technology over the last decade. We started off with a Model S with a range of 265 miles, and now a Lucid Air with more than 800 hp can do 516 miles between recharges.