A couple weeks ago, Volkswagen and Quantumscape claimed to have solved a key problem in the development of solid state batteries. Solid state batteries would give great benefits to both the automotive world and other industries, but have so far been frustrated by the inability to come up with a separator that can keep the battery from failing prematurely. Quantumscape claims that it has come up with a better separator that has been proven to work.

For those unfamiliar, batteries have cathodes and anodes, the positive and negative electrodes. These must be separated to prevent the battery from short circuiting. At worst, separation failures can cause fires and explosions, while at best, they prevent the battery from holding a charge. This separator must also be permeable to lithium or other ions that have to pass from one side of the battery or the other during charge an discharge.

With a solid separator and lithium metals, batteries would be much more compact for the same power output and storage capability. This would bring electric vehicles closer to being able to compete with fossil-fuel vehicles in terms of range and weight. When you consider that a gallon of gasoline contains 33.7 kWh of potentially usable chemical energy, and 3 gallons of gas weigh far less than a Tesla’s battery pack (plus is a lot smaller), there’s a big disadvantage. Smaller, more energy-dense batteries could close the gap quite a bit.

The problem with solid state batteries thus far is that the separators have all been plagued with problems. The separator needs to allow ions to pass through like a liquid battery, but without failing under stress or over time. High performing solid state batteries have thus far mostly fallen to dendrites, or little metallic crystal growths that eventually penetrate the separator and destroy the cell.

To make up for this, researchers have attempted many different compromises, like making the battery really low-powered or operate in unnatural temperatures and pressures. While this can work for some small electronic devices, these compromises make them unsuitable for automotive use. Low power would mean a giant, expensive battery pack. Unusual operating conditions would mean they take more power to keep them hot than they’re worth or they are susceptible to damage because they’re already under a lot of stress.

Quantumscape says it has come up with a ceramic separator that gives good power, doesn’t grow dendrites, and can last over 1,000 cycles. For multilayered batteries (which would be needed to power an electric car), it claims to have achieved over 800 cycles with similar capacity as the single layered cells.

You can read more in the company’s presentation here (PDF).

Some Skepticism is Definitely Warranted

None of this means the company is out of the woods, nor does it mean it is definitely going to market with affordable solid state batteries. Being able to make a few example/prototype batteries in the lab that can survive a lot of charges and discharges doesn’t mean that the technology to build them will scale well to producing millions or billions of cells to power electric vehicles. Even if you do accomplish that, having the final product cost less than current liquid-electrolyte lithium-ion batteries is even harder.

Quantumscape probably has some realistic-looking plans and ideas on how to accomplish all that, or it wouldn’t have been invested in heavily by the Volkswagen Group, but even the best companies sometimes make bad investments in technological dead-ends.

During CleanTechnica’s time reporting on this stuff, many companies making big promises of revolutionary battery technology have come, and they’ve all gone. The promised breakthroughs proved to be a lot more challenging than the company or researchers thought, or the batteries failed to perform. Given this history, we are definitely skeptical of any claims regarding battery technology until they’ve been proven a lot more.

If This Works Out Like They Hope…

Being able to produce affordable, energy-dense, powerful solid state batteries would definitely be a breakthrough. It would propel Volkswagen and Quantumscape ahead of the competition if they can get it done in the next 3-5 years like they are saying.

Energy-dense EV battery cells would be a game changer.

First, battery sizes and weights would be much smaller. This would allow vehicles to either have much greater ranges or it would allow them to be much lighter. You’d probably have automakers making long-range touring and hauling vehicles, but also produce sports cars that handle like small gas vehicles with “only” 500 miles of range or so. There would be much greater flexibility in vehicle design and capabilities.

Greater power densities would also mean more power. Electric vehicles already create massive low-end torque, but that would be even greater. Horsepower, which gives better high-speed performance, would be a lot better, too. That would make for electric vehicles that don’t struggle as much to accelerate at highway speeds as today’s slower EVs do.

Combine the greater power and the lighter weights (assuming you don’t want a 1,000 mile EV), and you could have a very powerful and nimble vehicle. The best gasoline-powered sports cars would still outperform it, but not by nearly as much as they outperform EVs on the track today. The gap would be a lot smaller.

The tire wear issues experienced by heavy and high-torque EVs would also be a lot less. Without all the weight pushing down, there would be a lot less stress on EV tires, leading to much better tire life.

Depending on how great the solid state batteries are, they may also give much higher charging rates. A vehicle that could add 500 miles or more of range in 5 minutes would take away one of the biggest advantage fossil fuel vehicles have at present.

For all of these reasons, the solid state batteries Quantumscape claims to be closer to building would definitely be a great thing, and would benefit it and Volkswagen more than other manufacturers until they could catch up or outcompete them in other ways. But, this is a gigantic if that isn’t a sure thing at all. Without a lot more evidence of their achievements and evidence that it can be made at scale for a decent price any time soon, we should all remain skeptical.

Featured image: A screenshot from Quantumscape’s recent presentation.



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