In a Surprising Binge of Transparency, Battery Companies Tell Us What They Really Have
By: Steve Levine
Tags: Tesla, Electric Vehicles, General Motors, Transportation, Lithium Battery

In a Surprising Binge of Transparency, Battery Companies Tell Us What They Really Have

Tesla, GM, and QuantumScape have begun divulging more and more data, but one battery maker just made perhaps the biggest reveal of all Steve LeVine Dec 15, 2020·6 min read

Solid Power’s 22-layer, 20Ah all solid-state lithium metal cell compared to the company’s first-generation 10-layer, 2Ah cell. Photo: © Solid Power

For the whole of the 140-year history of automotive batteries, researchers and their bosses have tended to secrecy. Even when forced to say something as a requirement of government or private funding, the default has been half-truths, and sometimes less. The main reason for all the hiding has been sincere: Batteries are hard and victories over the physics rare; usually you have nothing great to tell, and when you do, you want to hold it close.

Which explains the surprise in recent weeks as some of the most important actors in advanced batteries have unleashed a torrent of transparency. Not comprehensive openness, but enough data to satisfy battery researchers who have since been busily debating the releases on Twitter and elsewhere.

The news is that numerous companies appear to have broken through hurdles that have hobbled prior efforts to create super-batteries. If they can resolve their substantial remaining challenges, including on chemistry and manufacturing, they seem likely to give electric cars cost parity with combustion, a milestone that would finally put the price tag of EVs and gasoline cars on an even playing field. All the companies say they are aiming at deploying their breakthrough batteries in commercial EVs somewhere in the middle of the decade.

The data releases have been important because they involve the two most prized, yet-unreached battery compositions: anodes made largely of silicon, and those of pure metallic lithium. Being able to use either would substantially increase a battery’s energy density — and thus lower its cost and extend how far it could propel an EV on a single charge.

A question now is whether these top-tier companies have set a new standard for openness to which they and others will be held in the future.

Tesla is at the front of the pack in pure terms of volume of information. With its Battery Day presentation in September, Tesla helped us to understand most fully what it’s doing, including a partial silicon anode, and the upside (batteries at half the current cost) if it’s successful. In November, GM described achieving 500 charge-and-discharge cycles with its prototype metallic lithium anode. And just last week, QuantumScape said its own metallic lithium-based battery had achieved 800 cycles at room temperature and can recharge in less than 15 minutes. QuantumScape, which enjoys a fanatical following among battery experts, was the only company apart from Tesla to host a live webcast of its data release.

But the gold transparency prize goes to Denver-based Solid Power, whose December 10 release resisted the temptation to exclude unflattering performance data. Solid’s product is a solid-state metallic lithium anode.

Solid emphasized its main achievement, which was scaling up to a 22-layer, 20 amp-hour cell using conventional lithium-ion production equipment. It said the cell achieves specific energy density of 330 watt-hours per kilogram, which is higher than any known commercial lithium-ion battery. By comparison, QuantumScape said it has developed only a single-layer cell and now must work on scaling it up to be produced at commercial scale with about 100 layers.

In an interview, Solid’s CEO Doug Campbell told me that his objective is to scale up to a 100Ah cell and hand it over to automaker customers by the end of next year for the arduous process of getting qualified for use in vehicles. He said he is aiming to have the batteries in EVs by 2027. He also said he has submitted Solid’s cells for assessment by an independent third-party lab, and that he would release those results when he receives them in a month or two. QuantumScape has not thus far done the same.

Even more interesting: Campbell’s release of slides showing extremely low power for a separate 2Ah cell that was cycled at room temperature. It showed a drop in capacity to about 10% when discharged in one hour at 29 degrees Celsius. The better results with the 20Ah, 22-layer cell were achieved at high temperatures. This is significant because it’s thought that room temperature is a red line for the major automakers — none would even contemplate the added cost and complexity of adding a heating mechanism to the battery.

This disclosure startled battery experts on social media. Some of the experts expressed surprise that Campbell would even release such data, a sentiment that seemed to reveal the old way — open up about your battery only when you have something flattering to say. Notably, none of the other company releases revealed any flaws.

I asked Solid whether the performance was fundamental to the battery chemistry, or whether it could be resolved. The company responded by email: “29C operation was not even possible going back to 2019 and low temperature performance is advancing rapidly. Note that these are multi-layer multi-Ah cells, and our R&D-scale cells are already showing increased rate performance at various low temperatures. These R&D cell designs will be transitioned over to the production line in 2021.”

In other words, the company suggested, it expects to make the batteries perform better at room temperature in future iterations. If Solid is unable to do so, its market for the batteries could be severely constricted, said Venkat Srinivasan, director of the Collaborative Center for Energy Storage Science at Argonne National Laboratory. “SPs poor performance at room temperature limits it to niche markets, where the higher temperature may not be an issue,” he said.

Matt Lacey, a battery expert with the Scania Group, a Swedish manufacturer of commercial vehicles, told me, “Solid Power seems to have the challenge that while they can produce cells of the right size, they will struggle to convince vehicle manufacturers to make a big commitment until they can show evidence they can meet practical needs. Aspects like cycle life and safety can be flexible maybe, but high power and low temperature performance are more fundamental.”

Campbell told me by email that the focus in terms of this data should be on scaling: “Yes these large format cells are still not meeting all automotive requirements. However, what is particularly exciting here is that in addition to demonstrating the ability to produce truly solid-state batteries at-scale, we have demonstrated at or near full compliance to all automotive requirements on lab-scale cells produced using 100% scalable methods. What was achieved this year was translating many of those developments into production line cells. These included cell level energy, discharge rates, and what would appear to be cycle life (obviously this has to be measured but as of now we’re tracking in the right direction).

“As demonstrated in the second half of the release, our latest cell design iteration is now showing at or near full compliance with automotive requirements including high charge rates and low temperature operation. Thus, we now have a clear path to truly all solid-state, multi-layer, EV-scale cells meeting automotive requirements — and not in several years but next year.”

It’s not clear what precisely has motivated the battery confessionals. Does it reflect the very new stakes now that a true super-battery actually seems doable and relatively near? Is it the greater competition for customers among the automakers? Whatever the case, it has intensified the drama around the battery game.