At the beginning of September, the distinguished battery researcher Jeff Dahn, who runs a lab at Dalhousie University in Nova Scotia, released a report about a new battery formulation that could power an electric vehicle for 1.6 million kilometers (or 1 million miles). And since Jeff Dahn and his team are Tesla research partners, the public speculation of what this could mean for Tesla’s upcoming battery tech kicked into high gear. I’ve put together several videos myself on the future of battery technology, battery recycling, and where Tesla may be heading with the Maxwell Technologies acquisition, so it should go without saying … I got pretty excited when I saw this news spring up. While the 1,000,000 mile battery is a great headline, my curiosity went into over drive, so I read through Jeff Dahn’s research paper and talked to an expert to see if I could tease out some of the details. And it may not be exactly what you’re expecting.
Jeff Dahn has been researching lithium-ion batteries for decades, and is one of the people responsible for the batteries we all take for granted in our laptops and mobile phones today. He knows his stuff, so when he and his team publish a report like this, people listen. After reading through the report myself, there were a few key things that jumped out at me.
This formulation shows very little degradation over time and can withstand full depth of discharge cycles better than your typical lithium-ion battery. On a typical battery you can expect the equivalent of 1,000 cycles from 100% to 0% charge and back again.1 Getting to 1,000-2,000 cycles is considered good. The test formulation from Dahn’s research was showing over 95% of the original capacity available after 1,000 charging cycles. Compare that to the standard formulation they tested with about 50% capacity left after 1,000 charging cycles. Even after 4,000 charging cycles, the test batteries were still showing capacities of around 90%. That’s … kind of crazy.
One of the other pieces of the report that jumped out at me was temperatures. We all know that batteries don’t like extreme temperatures and it impacts performance. But it can also impact the overall lifespan of a battery too. These tests showed that this battery is very resilient and doesn’t take much of a hit. At 40C (104F) the test formulation showed 90% of the original capacity after 3,500 charging cycles. To quote directly from the report, “this cell chemistry is extremely tolerant to extended periods at elevated temperatures.”
So it really sounds like this may be the battery we’ve all waiting for, right? Yes, but not exactly … because there’s a nuance to this that wasn’t immediately clear at a quick glance. In fact, there are two things worth calling out.
First, the formulation tested was a 5 parts Nickel, 3 parts Manganese, and 2 parts Cobalt recipe. NMC batteries are commonly used pretty much everywhere today like our phones, laptops, power tools, and even some EVs. It’s a very effective battery formula that has a solid track record, and the version tested has a specific energy of 200 wh/kg. The battery cells in the Model 3 are somewhere around 250 wh/kg.2 While these tested batteries may be able travel 1,000,000 miles over their lifetime, with the lower specific energy of the NMC battery, they won’t be able to travel as far on a single charge as the current Tesla NCA battery. The difference may be something like 260 miles versus the 310 miles we get today on the long range Model 3.
The second thing that surprised me was that the tested formulation has more cobalt than Tesla’s current batteries. And unless you’ve been avoiding the news on cobalt, you’ll know that there’s some serious issues with cobalt mining. It’s very dangerous work and some mines, like in the Democratic Republic of Congo, have been exploiting workers.3 The rarity of cobalt also makes it very expensive. Tesla and other companies have been trying to reduce their dependence on cobalt with new formulations, which is something that Elon and his team have talked about on quarterly calls in the past.4
So with this tested formula using more cobalt than Tesla’s current batteries, it raised the question: is this really a formula that Tesla will even use? The answer is most likely no. As excited as everyone got over this report, this specific formulation doesn’t align with Tesla’s stated goals. They’re committed to reducing or even eliminating cobalt from their batteries, not increasing it. And they’re also committed to reducing the cost of manufacturing their battery pack, and in turn the car, to make it more affordable in the market. Cobalt is very expensive, so if you used this formulation you might see the cost of the battery pack rise by $400 – $500. Which again, doesn’t align with Tesla’s goals.
What this could mean?
I’m not trying to be wet blanket here and make this report sound like it’s not worth celebrating. It is exciting research, but it’s just that … research. This is one piece of a much larger puzzle. We shouldn’t expect that this is exactly what we’ll be seeing in our cars in a couple of years. This could be a good fit for Tesla’s Megapacks and grid scale storage systems because they aren’t as constrained for size and cost, but that doesn’t feel like the ultimate answer either.
This report is surfacing some key findings around a single crystal cathode with protective nano-scale coating. While it seems like the report may be giving up what seems like proprietary information with the single crystal, it’s important to remember that research like this takes time and is done in phases. It’s about methodically testing the different building blocks of the battery to zero in on what combination will result in the perfect fit for a certain use case. Jeff Dahn actually has a paper on single crystal vs. polycrystalline in lithium-ion cells from 2017.5 So this current paper is an extension of that previous work combined with other research and experiments that they’re doing. This latest paper was released to help the research and automotive community to demonstrate the latest lithium ion technologies and benchmark it. Battery research is extremely complicated and the artistry comes with how you combine these different techniques and chemistries together. That’s the secret sauce.
And that’s why, after reading this paper, it’s clear to me that there’s still another shoe to drop … or a couple more shoes to drop. I have no doubt that Jeff Dahn and his team have research currently in progress on single crystal chemistries that will make more sense in Tesla’s cars. Combine that with Maxwell Technologies Dry Battery Electrode manufacturing technique that Tesla acquired, and then we could be talking about the million mile battery in Tesla cars. Something that lasts for the life of the car and is cheaper to produce. Most likely a formula with very little or no cobalt.
The big tell will be what, if any, papers Jeff Dahn releases around the end of this year or early next year. And we’re also waiting on Tesla to hold their battery and drivetrain investor day event, which has been pushed into early next year. This research paper isn’t the destination, but it’s a sign post along the road towards that destination. It’s a very clear hint as to where things are going.
So why a million mile battery?
A million mile battery for a typical driver is a little nutty. The average American driver puts on about 13,000 miles each year.6 That means it would take the average American driver almost 77 years to drive 1,000,000 miles. Why would Tesla even want to have a car with motors and battery packs rated for that number of miles? The answer is, it’s not meant for us, the average driver. Tesla is looking towards things like the self-driving robo taxi future. Let’s look at the average New York City taxi cab, which travels over 70,000 miles per year.7 For that you’d be looking at about 14 years of use before the battery and motor may need replacement. That’s longer than the average New York City cabs lifespan of 3 to 4 years.8 Long distance semi-trucks can drive upwards of 100,000 miles per year,9 so you can also see how this could tie into Tesla’s Semi.
But building out batteries this resilient also benefits longevity and scenarios with high depth of discharge rates. Just take a look at grid-scale energy storage. The batteries that Dahn’s group tested could last at least 20 years as part of an energy storage system, which are systems that will be cycling charges a lot over their lifetime. A perfect example for how this could benefit grid scale energy storage would be something like the Hornsdale Power Reserve in Australia,10 which Tesla built for $50 million. In the first six months of operation it was responsible for 55% of frequency control and ancillary services in South Australia. And by the end of last year was estimated to have saved $40 million is costs.11 Taxis and trucks will also be cycling a lot more than the average drivers electric vehicle. Working and driving all day, rapid charge, and then repeat. Not the 10 – 20% battery drain, sit and wait, drive again scenario that the average driver does with a car. The longer these batteries last, the greater the return on investment (ROI) the owner of the car or energy storage system will see.
I was very excited when I saw the initial reports of Jeff Dahn’s research, and it’s advancements like this that show there are still big gains to be made in battery technology. But it’s always important to try and look past the headline and understand what the research is actually doing, and to understand that its arrival in our lives may not be right around the corner. But having said that, I’m really excited to see what Jeff Dahn has cooking in his labs that will eventually end up in our cars and probably powering parts of the electrical grid at some point in the future. It’s research like this that is not only going to make our cars even better than they already are, but help to make a brighter future.
http://seekingalpha.com/article/4291405-teslas-million-mile-battery http://fortune.com/2015/06/17/meet-teslas-new-weapon-a-battery-scientist/ http://jes.ecsdl.org/content/164/7/A1534.full http://insideevs.com/news/369030/tesla-manufacture-own-battery-cells/ http://www.youtube.com/watch?v=18MYRkx_Vr4&t=209s