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Solid state batteries have been hyped for years as a silver bullet for making EVs mainstream, improving consumer electronics, and … well … everything. It’s 2022 and they still aren’t here in any meaningful way, but there have been interesting advancements that are worth exploring. However, with several other battery technologies popping up offering similar or better energy density, lifespan, safety, and costs, (all of which are solid state batteries’ big sales pitch) is solid state still the future of energy storage tech? Let’s see if we can come to a decision on this.

It feels like there’s a big battery breakthrough happening every week, and it’s no surprise given the amount of interest and money going into renewable technologies like EVs and energy storage for solar and wind power. There’s a race to come up with the next big thing in battery tech, which is why I keep talking about it on the channel.

Finding a better battery technology that can offer improved energy density, lifespan, safety, and cost is essential for not only EV adoption, but for our transition away from fossil fuels in general. Energy storage is the key to a lot of things. As my team and I have been developing these videos, I’ve had the opportunity to talk to quite a few people in the energy storage and battery research sector. In fact, I’ve had a few recent interviews and videos on some interesting new battery technologies, which have started to make me question solid state batteries’ holy grail status. There are three good examples of new battery technologies that showcase why I think solid state batteries may not be the silver bullet we’re looking for. But then, why the continued interest in solid state?

Traditional lithium ion batteries are great, but they still have several drawbacks that have been limiting wider electric car adoption. Lithium-ion batteries require protection and management circuits to prevent them from being overcharged and discharged, which increases costs and complexity. They also suffer from aging whether they’re in use or not. They also weigh a lot (accounting for about 1/3 of an EV’s weight). Finally, they’re expensive, and while the price has been decreasing, the cost is still significant.1 2

All these issues are why researchers and companies are continuing to seek new battery technologies that can overcome the problems of traditional lithium ion batteries … and solid state has been one of the most hyped solutions for years. For a super quick recap of why…

Batteries are composed of an anode (the negative side), a cathode (the positive side), a thin layer made from a polymer that acts as a physical separator and insulator, and finally an electrolyte, which is a substance that chemically reacts with the anode and cathode. The battery ions move through the electrolyte between the electrodes, and this movement of charged particles produces current.

Currently, lithium batteries use a liquid electrolyte but this raises problems regarding flammability, risk of leakage, and electrolytic decomposition at high voltages. On the flip side, solid state batteries use a solid electrolyte rather than a liquid solution, and the solid electrolyte also plays the role of a separator. As a result, it serves as an ion transport pathway, as well as an electric insulator and mechanical separator between the anode and cathode. 3 4

Because solid state batteries don’t contain any liquids, they’re considered safer. If a liquid electrolyte battery is punctured, it can cause an explosion. In comparison, solid electrolytes are nonflammable and the battery can still safely operate while punctured, without leaking or exploding.

Another pro of solid state batteries is that they’re estimated to have energy densities 2.5 times higher than current lithium-ion batteries (currently 250-270 Wh/kg), which means that the battery could be lighter while storing the same amount of energy. On top of that, according to researchers, solid state batteries will be able to recharge 4-6 times faster than current lithium technologies without compromising safety. That factor could be a game-changer in marking EVs as charging time is one of the biggest reasons consumers are EV hesitant.

In my 2021 solid state battery update video, QuantumScape had announced their solid state cells have a 1,000 Wh/L energy density and could charge to 80% capacity in 15 minutes. By weight, it offers somewhere between 380-500 Wh/kg. At the time we didn’t have much real data and the company wasn’t expecting to start producing its batteries until 2024. Around the same time period, Toyota had teamed up with Panasonic to develop EVs with batteries that had twice the travel range when compared to a standard lithium-ion battery. They were rumored to be unveiling a solid state battery EV, but they ended up stating that it won’t be in mass production until 2025.

Obviously a bit disappointing to see that they’re several years away, so where do things stand today? In April 2022, Nissan announced a prototype production facility for solid state battery cells, intending to launch a pilot production line in Yokohama. Just like last year’s announcements, we’re looking at 2024 for battery production and electric vehicles in 2028. 5 Right now the batteries are still in the prototype phase with small cells around 2 cm² with a single layer and 20mAh of capacity. The company will be conducting a feasibility study at laboratory scale later this year in order to make larger cells with more layers in the 3-5 Ah range and around 10cm in size. 6

Nissan’s labs in Kanagawa Prefecture, Japan, are concentrating on material combinations and production scalability. Partnering with NASA and some researchers from the University of California San Diego, they’re evaluating combinations of hundreds of thousands of materials using a computerized database to figure out which ones will work best for developing new battery technologies. 7 For now, Nissan has picked a sulfide-based solid electrolyte for its battery. Regarding costs, Nissan predicts that their solid state batteries may be in the $75 per kWh range by 2028 and could possibly be reduced to $65 per kWh later. 8

Getting back to QuantumScape, the startup released a white paper in January 2022 showing data for a single-layer of their lithium metal solid state battery, which was able to retain more than 80% of its initial energy after 400 cycles of 15-minute fast charging at temperatures of 25 °C and 45 °C.This is a great result considering that current EV lithium ion batteries typically need around 30 minutes to fast charge from 10% to 80%.

According to QuantumScape, 400 cycles on an electric car with a range of 300 miles equals about 120,000 miles. However, that falls short of the more industry standard 800 to 1,000 cycles and there are companies going well beyond that already. Before criticizing that deficiency, remember that they’re still stepping their way to mass production in 2024. 9

As part of that process they’ve also been testing increasing the number of layers in their battery cells. In its 2022 Q1 letter to shareholders, the company stated that its 10-layer cells were successfully tested by one automotive customer and entered the testing phase with another. Just recently, in May 2022, the company announced the production of a 16-layer solid state cell capable of 500 charge cycles. The cell’s energy retention and cycling have so far mirrored that of the preceding cells, so there’s forward progress being made.

QuantumScape also provided updates on the scale of its operations, including the target to reach weekly production of over 8,000 separators. Thanks to upgrades to production tooling on its phase 1 engineering line, the company’s average weekly production increased to almost 3,700 this quarter compared to 2,000 at the end of 2021. 10

The company stated:

“In Q2, we aim to complete production qualification for the majority of the tooling for the Phase 2 engineering line, including automated cell assembly tools, ultrasonic welders and cell testing systems. We continue to target the delivery of A-sample cells to at least one customer in 2022. The A sample is planned to have dozens of layers and is intended to demonstrate the core functionality of the battery cells…” – QuantumScape10

In both cases with Nissan and Quantumscape, there’s an important thing to keep in mind. For mass production of cells and mass adoption, we’re looking at dates somewhere between 2024 and 2030.This is where I’m starting to question if solid state batteries have lost a little bit of their mojo because there are competing technologies also trying to address increased energy density, safety, lifespan, and costs. All of the problems that are supposed to be solved by solid state batteries. There are three other battery technology examples coming onto the scene that achieve some of the same benefits as the original promises of solid state battery technologies.

A team of chemical engineers from Drexel University has recently discovered a way to inject sulfur into lithium-ion batteries, which could reduce the need for Cobalt, Nickel and Manganese. Drexel researchers attempted to address the volatility of lithium sulfur batteries with a novel technique using a carbonate electrolyte to restrict sulfur inside carbon micropores physically, and they got exciting and unexpected results.

The sulfur cathode has remained stable after more than a year of testing, and its performance held up through 4,000 charge-discharge cycles, which is equivalent to 10 years of normal use. Compare that to QuantumScape’s solid state battery retaining 80% after 400 cycles of 15-minute fast charging. Drexel’s lithium sulfur battery capacity reached more than three times that of a Li-ion battery, which is 20% higher than the capacity of a solid state battery.

However, a big problem with lithium sulfur batteries is cost (it’s still early days), which is projected to be around $200/kWh, far above what’s expected for solid state. Time is also another stumbling block. At the moment, this tech is still in the lab and it needs to undergo several tests for validation and scale up to production numbers before hitting the market. 11 12

I had a chance to talk to Dr. Vibha Kalra, who is lead researcher about this.

“We’ve been talking to a lot of industry folks to get an understanding of the steps beyond where we are right now. And our understanding for such a technology would be more in the range of five to six years.” -Dr. Vibha Kalra

You can get more details on the development of this battery tech in my lithium sulfur battery video, but on the solid state battery hit list, this ticks off the boxes for energy density, safety, and lifespan. Depending on how this goes, it may be able to hit the cost checkbox too, but only time will tell.

Another technology that offers fast charging, great energy retention after thousands of cycles and lower heat generation than conventional lithium-ion batteries is the niobium battery, manufactured by Battery Streak. This battery is capable of charging up to 80% in only 10 minutes with a 6C rate while generating a small quantity of heat. In addition, it can retain 90% of its capacity after 3,000 cycles — a number of cycles almost 8x higher than what we have in QuantumScape’s solid state battery. 13 14 The company isn’t 100% sure when their battery will hit the market, but they’re entering pilot production with partners. You can get to know more about it in my Battery Streak video.

And we can’t forget about Tesla ramping up production of its new 4680 battery, which can store 6x the power of a conventional 2170 cell and will enable a 16% energy boost in range. In addition to increasing range, Tesla claims that the 4680 battery will slash the cost per kWh by 56%. Unlike solid state batteries, which will take years to officially hit the market and power EVs, Tesla reported in January 2022 that it manufactured one million of its 4680 battery cells at its California pilot plant. They have also claimed it’s already preparing to deliver its new Model Y outfitted with the 4680 cells and structural battery pack. 15 16 It’s not solid state, but by optimizing the engineering, chemistry, and production process, they’re achieving two of the most important factors: cost reduction and range improvement.

So given the growing competition that’s chipping away at solid state’s one battery to rule them all status, is it still worth it? Is it still something we need? I’d say yes. There’s never been a magic bullet to any of this. It’s always been about choosing the right tool for the job. We have a variety of batteries and energy storage options today, and we’ll need an array of choices for the future too. Even though the hype for solid state was overblown, there’s definitely a place for it in the market … and use cases where it makes a lot of sense. Tesla’s achievement is important because it’s rolling out now with even more advancements in the works. Battery Streak’s Niobium battery tech is going into pilot testing with partners this year, but there’s no telling how long it will take to hit the wider market. And Drexel’s lithium-sulfur breakthrough is still early, early days, but has a lot of promise. The global solid state battery market is expected to grow from $92 million in 2021 to $1.6 billion by 2030, according to Precedence Research 17. The thing I took away from all of this is that solid state is making good progress, but is still years away from mass adoption … and that it’s still something to keep an eye on and be excited about. Just this past June Solid Power announced that they’re about to begin pilot manufacturing of their solid state battery in Colorado18. Like I said, it feels like a new battery breakthrough or announcement every week. Just keep expectations in check and remember there’s no one solution to solve all our energy storage needs.

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Matt Ferrell
Matt Ferrell lives in the Boston area and is a UI/UX designer by trade, but has always been obsessed by technology and how it works. In 2018 he started his YouTube channel, Undecided with Matt Ferrell, where he explores sustainable and smart technologies like EVs, solar panels, and smart homes.

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