Why Solid State Batteries are Finally Here (Almost)

If I said that solid state batteries (or  SSBs) were coming to the market soon,  

would you believe me? What if I told you that  some of the most advanced SSBs ever made are  

right around the corner? And that the pilot  programs and production facilities are already  

in the works? I wouldn’t believe me either, but  it's true. For the longest time, SSBs have been  

one of those revolutionary breakthroughs that  was always just another five or so years away.  

But now two companies, QuantumScape and Solid  Power, are on schedule for commercialization.  

So how exactly are they bringing their SSBs  to the market? And what makes them special?

I’m Matt Ferrell … welcome to Undecided. 

This video is brought to you by  Brilliant, but more on that later.

Solid state batteries have been hyped up for years  and it’s easy to see why. Compared to the current  

gold standard of lithium-ion (LI) batteries,  solid state batteries are more energy dense,  

longer-lasting, safer, smaller, and  have the potential to charge faster.  

I think we’d all appreciate an EV that  can charge to full in just a few minutes,  

or a laptop that only needs to be charged once  or twice a week. Either that or a laptop or phone  

that has the same battery life we have today, but  is impossibly thin because of a smaller battery.

Unfortunately, solid state batteries are one of  those technological breakthroughs that’s had some  

trouble actually breaking through. While a vast  variety of solid state batteries made from all  

sorts of different materials have performed well  in lab settings, getting them onto the market has  

proven to be challenging. Both Solid Power and  QuantumScape have supposedly solved that issue,  

but for this to make sense, let’s brush up  on some solid state battery basics first.

We’ve talked about SSBs on the channel, many, many  times, so I’ll keep this brief. In an ordinary  

battery, you have a cathode and anode. These are  separated by a, uh, _separator_ ... and a liquid  

electrolyte solution that allows ions to flow  freely between the two sides during charge and  

discharge. Liquid electrolytes, however, are prone  to leakage, thermal runaway and dendrite growth.  

Dendrites are essentially metal spikes that grow  as the battery is cycled over time. They can cause  

the battery to short out, or even puncture it,  which in rare cases can result in explosions.

So, why not replace the liquid electrolyte  with a more stable solid? Congratulations,  

you now understand the “solid” of solid  state. And as we noted just a moment ago,  

solid state batteries tend to be lighter and  more energy dense than the competition. This  

is because a solid electrolyte can get the same  amount of umph as a liquid one in less space.  

This makes them pretty tantalizing for  EVs, where weight and power are critical.  

Seems like its all upsides, so what’s stopping  these batteries from hitting the mass market? It  

mostly comes down to materials and manufacturing.  solid state battery components are finicky. They  

require very specific manufacturing techniques and  specialized machinery. Typically, their cores are  

made out of ceramic or glass and are challenging  to mass produce. And for most solid electrolytes,  

even a little bit of moisture can lead to  failures or safety issues. As a result,  

solid state batteries need to be manufactured  in extremely controlled conditions. The actual  

manufacturing process is also very labor-intensive  right now, especially compared to traditional  

lithium-ion batteries. That all adds up to make  manufacturing them prohibitively expensive.

So how are QuantumScape and Solid Power  dealing with these challenges? What solid  

state battery formulations did they go with?  And why are their batteries leading the pack?

Let’s dive into QuantumScape first. It feels like  everytime we talk about solid state batteries,  

they seem to show up. Based in California,  QuantumScape has spent years leading up  

to their first commercial product, the  QSE-5 solid state battery. Previously,  

QuantumScape has said they were aiming  for commercial battery production in 2024,  

and credit where it's due, they’re  pretty close to hitting that deadline.

One of QuantumScape’s core innovations is their  anode-free battery, which sounds bananas. As I  

mentioned earlier all batteries have an  anode and cathode. Normally a silicon or  

graphite anode stores the lithium atoms  until they are ready to be discharged.  

Instead, they’re using a highly  dendrite-resistant solid electrolyte  

separator. This allows the lithium metal  itself to act as the anode. Ordinarily,  

the lithium has to diffuse through another  anode material, which creates a bottleneck that  

slows charging speed. But Quantumscape’s method  eliminates this bottleneck, so its battery is far  

more energy dense. The end result: shorter travel  distance for ions and overall faster charging.

solid state batteries charge fast alright —  that’s part of the draw. But by eliminating  

the anode bottleneck, QuantumScape's battery  can charge to full in less than 15 minutes.  

This is especially important for the world of  electric vehicles (EVs). Along with range-anxiety,  

one of the remaining EV-adoption  hurdles is charge time. As long  

as it’s faster to fill a gas tank than  charge a battery, some people are going  

to have their doubts about EVs. That’s why  QuantumScape is angling for the EV market.

Speaking of the market, that’s another  benefit of the anode-less design:  

Quatumscape doesn’t need to spend money on  making an anode. Considering that cost is  

one of the things holding back solid state  batteries, every little bit helps. It also  

saves some space and weight, which again,  are important considerations in the EV-world.

And there’s even more benefits to QuantumScape’s  design, which I’ll get to in a minute.  

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channel. Like I mentioned earlier, there’s  other benefits to QuantumScape’s design.

And there’s yet more benefits to QuantumScape’s  design: it increases the batteries lifespan.  

The anode is where a lot of those nasty,  life-shortening chemical reactions take  

place. Without that anode, QuantumScape claims  their battery can go for 2,000+ cycles. Most  

lithium EV batteries can run for around 1,500  to 2,000 cycles, so QSE-5 isn’t lagging here.

Another neat feature of the QSE-5 is its  housing. Lithium-metal batteries like the  

QSE-5 have a tendency to balloon up if you  fast-charge them. If you’re planning to stack  

a bunch of these batteries together, like for an  EV battery pack, this can be difficult to engineer  

around. So QuantumScape has forgone the usual  cylindrical battery frame, opting for a combo  

box-and-pouch they’re calling the FlexFrame.  There's a central pouch that’s built to swell,  

and when it does, it rises until it's flush with  the boxy frame. This little engineering trick  

ensures that the batteries have room to grow  and shrink while remaining tightly stackable.  

Pretty clever when you’re trying to maximize  the space, weight and energy density for an EV.

Let’s turn now to Colorado-based Solid Power.  Rather than changing up their architecture,  

they’ve got a novel battery formulation. The  company has three batteries that are approaching  

commercialization, all with a sulfide-based  solid electrolyte separator. We'll focus  

on their Silicon EV battery though, because  that’s the furthest along. Their solid sulfide  

separator offers the usual solid state battery  benefits along with its own interesting perks.

Sulfides have great ionic conductivity, with  some even close to liquid electrolytes. This  

means that lithium ions can travel through  sulfide-based separators with less resistance,  

helping with faster charging times. They’re  also flexible, so they can roll with punches  

instead of snapping like more common and brittle  glass or ceramic solid state battery separators.  

These materials have shown remarkable heat  resistance, which is great because batteries,  

even solid state ones, do tend to get  pretty hot. And recent studies suggest  

sulfides can be moisture resistant when properly  treated. Considering how temperamental solid  

electrolytes can be around moisture, this has  the potential to make manufacturing much easier.

Ease of manufacturing might be sulfide's  greatest strength. Sulfide solid state  

batteries can be produced with roll-to-roll  battery manufacturing equipment, which is  

very common in the industry. And sulfides  can be manufactured relatively cheaply from  

abundant materials too, helping them avoid  many supply chain issues. All together,  

Solid Power claims they can manufacture its  solid state batteries for cost savings of  

15-35% less than their competitors. Seeing as  the price is one of the major limiting factors  

of solid state batteries, that kind of  cost saving is nothing to sneeze at.

Now that you have a handle on who  we’re dealing with, let’s dive into  

the nitty-gritty stats. Which battery is  better for an EV? Which will hit the market  

first? And what challenges still remain? ## QuantumScape & Solid Power Pros & Cons 

Rather than slow things down by listing off the  stats one-by-one, we’ve got a graphic for you.

In addition to the QSE-5 and  Solid Power’s EV battery,  

I’ve also added Solid Power’s other batteries.  And for the sake of context, we compare these  

batteries with Tesla’s 4680 cylindrical cells,  currently used in the popular Tesla Model Y,  

and now with the Cybertruck. If this looks  intimidating, don’t worry. We’ll break it down.

Let’s look first at volumetric density. This  is a measure of how much energy a battery  

can store within one liter of its volume. The  denser the battery, the bigger the “tank,” so  

to speak. Tesla weighs in at around 622 Wh/L,  the QSE-5 beats that by about 200 watt-hours,  

and that in turn is bested by Solid Power  by around a hundred watt-hours and change.

There's no definitive evidence or statement  for how far a car with QSE-5 or Solid Power  

EV battery will go on a single charge.  However, the less dense Tesla Model Ys  

are estimated to run for 300 to 330 miles  (or 482 to 531 KM) on a single charge,  

so it’s likely the solid state batteries  will rove for a fair bit further.

Next we have cycle life … and I’m not talking  about e-bikes. This is the amount of times a  

battery can be fully charged and then  fully discharged before its capacity  

starts to fall off significantly. You can  see that Tesla clocks in between 1000-2000  

cycles. Solid Power fits on the lower end  while the QSE-5 leans toward the upper end.

Now let’s talk charge time. Tesla’s batteries  can “supercharge" in 15 to 25 minutes,  

but it's not recommended. Charging  your car this fast on a daily basis  

can really shorten its lifespan. Tesla  says you should go for a more casual  

home charging method that’ll give you a  full charge in 8 to 12 hours. But solid  

state batteries? Both QSE-5 and Solid Power’s  batteries can readily do charge times of 15  

minutes with minimal side effects, though they  achieve this through very different methods.

For Solid Power, sulfides’ softness  is the solution (try saying that 10  

times fast). Just like it's easier  to swim through water than Jell-O,  

it's easier for ions to move through the softer  sulfides than some other separators. Fast,  

smooth-sailin’ ions equals fast charge  times. Meanwhile, QuantumScape is fast  

because their oxide separator can handle  higher voltages. This is a clunky explanation,  

but a higher voltage means we can “force”  more ions through the separator. In this case,  

more ions equals fast charge times. Higher  voltages tend to speed up dendrite growth  

and cut into the battery’s lifespan, but  the QSE-5 is tough enough to handle ‘em.

Last, but far from least, there’s  the release dates. Which battery is  

making it to the market first? Both companies  are already capable of making small batches of  

their batteries. QuantumScape hasn’t  issued an official commercialization  

timeline. The company is pleased with  the small batches it can do right now  

and is preparing to introduce and scale-up  their “Cobra” production system in 2025.

QuantumScape claims that this will allow them  to mass-produce solid state batteries at the  

gigawatt scale. From there it shouldn’t be  too much longer to full commercialization.  

Solid Power hasn’t issued an official mass  market goal date either, though their CEO,  

John Van Scoter, told the Denver Post last  September that he predicts 2028 will be the  

year that EVs are regularly powered by solid  state batteries, Solid Power’s included. So  

while neither battery is hitting the market next  year, these are significant milestones, and it’s  

looking like we truly have broken away from  the “just another 5 years, please” catchphrase.

I do want to temper some of the excitement by  drawing attention to the engineering problems  

that still remain for each style of solid state  battery. For sulfides, their vulnerability to  

dendrites still needs to be addressed. We’ve found  a few ways to tackle this issue but none of them  

are perfect. Running the sulfide battery extra hot  fights dendrite growth, but it also means adding  

extra heat management devices. That cuts into the  cost and weight. We could put the sulfide battery  

under pressure, but that’s tricky to do outside  of the lab. Running the battery on low power could  

also work. Though, it’s a bummer to have a high  performance battery and not let it perform highly.

QuantumScape’s oxides have their own issues. Most  notably, it’s still challenging to mass produce  

them. This is because they must be sintered  together at  

very high temperatures, an expensive and energy  intensive process. Meanwhile, sulfides can be made  

relatively cheaply and easily with some common  industry techniques like roll-to-roll processing.

## Which is Better? So, which battery is  

better? There’s no clear cut answer. They’re  at slightly different stages of maturity,  

with different strengths and weaknesses. As  we often find with these sorts of things,  

neither is a silver bullet. I think  each one will settle into its own niche.

I want to re-emphasize that the outlook for  both batteries is promising, at least at the  

time of writing. Last year, QuantumScape  deployed the very-cool sounding “Raptor,”  

a high speed throughput separator process that  allowed them to efficiently produce some QSE-5  

prototypes for its auto company partners like  Volkswagen. It’s planning on shipping their A2  

round of samples to its partners for further  testing this year. But if you liked Raptor,  

you’re gonna love Cobra. We mentioned it a  moment ago, but Cobra is the upgrade to Raptor,  

and should help QuantumScape affordably mass  produce its oxide separator at triple the current  

speed.[^31 That said, the QuantumScape team does  caution that the Cobra is a work in progress,  

so it’s not like the manufacturing  challenges are done and dusted.

For their part, late last year Solid Power inked  a deal with SK Group, the biggest company in  

Korea behind Samsung. This three-year contract  gave Solid Power a $20 million boost on top of  

an earlier $130 million investment from Ford.  Thanks to this kind of support, Solid Power is  

already capable of producing 1.1 million metric  tons of their sulfide electrolyte per month! The  

company’s own A1 cells are already out the door,  and it’s planning to have its A2 cells out soon.

With that in mind, I still want to be careful  and not overhype solid state batteries and feed  

into the idea that they’re a holy grail and  _the_ thing to hold out hope for. solid state  

batteries are going to be huge when they  hit, but they need a little more time. So  

if you’ve been waiting until solid state  batteries are around to switch to EVs or  

install home energy storage, I’d quit waiting  and get the product that fits your needs today.

But what do you think? Do you think solid state  is the next big thing and worth waiting for?  

Jump into the comments and let me know and be  sure to listen to my follow up podcast Still  

TBD where we’ll keep this conversation  going. I’ll see you in the next one.