Ever wonder what goes into building some of the world’s most advanced battery technologies? In the first part of the Behind the Battery series, Electric Autonomy visits the Jeff Dahn Research Group to find out what makes the lab so appealing to Tesla
The hallways of the Jeff Dahn Research Group labs, a lithium-ion battery R&D facility of international fame, are oddly still.
It’s late August and the group’s namesake physicist is on holiday.
Down the hall from Dahn’s office 30 or so summer students and post-grads are sitting in a stuffy lecture room listening to a presentation.
To the untrained battery scientist (i.e. this reporter waiting in a hallway lined with Tesla pictures) it seems like, for the moment, all work has stopped.
But it hasn’t.
When you are spending a million dollars a year trying to develop the world’s most technologically advanced batteries for one of the world’s most famous (or infamous) automakers, there is, often literally, no rest.
From Dunn to Dahn
The sun is beating down on the Sir James Dunn Science Building on Dalhousie University’s campus in Halifax. This is where the Dahn Research Group does its work.
It’s a classic three-storey, stone low rise named for a man who became the president of Ontario-based Algoma Steel near the peak of the Great Depression (and then went on to donate a lot of money to Dalhousie).
In 1935 Dunn assumed control of Algoma and went to great lengths to salvage the company from bankruptcy and receivership. Today Algoma is a lynchpin supplier in vehicle manufacturing.
And, now, almost 90 years later, the scientists housed inside Dunn’s building (a select few dozen from around the world) are dedicating 24 hours a day, seven days a week to transforming that same auto industry.
The Jeff Dahn Research Group is responsible for watershed discoveries in the electric vehicle world. Many appear in Tesla cars on the road today. The breakthroughs range from the “million-mile battery” (more on that and why it’s misnamed later) to the recent discovery that the green tape holding the components together in almost every EV battery around the world is actually lowering range.
“Batteries are the absolute core technology for all the Tesla vehicles,” says Michael Metzger, the Herzberg-Dahn Chair for Advanced Battery Research, Department of Physics & Atmospheric Science and an assistant professor of physics, in an interview with Electric Autonomy.
Metzger is one of two scientists hired by Dalhousie in January 2021 when its partnership with Tesla was renewed. He and Tesla Canada Research Chair Chongyin Yang are tipped to be key figures in the Dahn Group’s succession plan — if and when its namesake retires.
(Note: this is not a Dahn retirement announcement nor is there any indication one is coming. But, as with most high-stakes things, it’s prudent to be prepared.)
“We have really close interactions with scientists and engineers at Tesla,” says Metzger.
Apparently, Tesla’s scientists at the automaker’s Dartmouth lab regularly come to Dalhousie to run tests.
“We have five big goals that we agreed on — Tesla and us. These are: cost, energy density, safety, lifetime and sustainability.”
Metzger’s enthusiasm about the Dahn Group and Tesla partnership is palpable.
By his account there is a yin and yang dynamic between the two institutions. One is a fast-moving, ever-hungry business. The other a slow-moving, diligent academic lab.
But it is the ideal combination to create a cutting-edge technology incubator.
“We wait sometimes for two or three years before we can publish a research paper. Not a lot of researchers do that. We can do that because we have long-term funding from Tesla. Others need to show immediate impact and publish data,” says Metzger.
“[Tesla] wants to work with us, I would say, because we try to do things very carefully and really understand how we can improve batteries.”
Types of batteries
Metzger explains the Dahn Group and Tesla’s broad goals are intentionally vague, which is helpful when nurturing innovation.
“Within those categories there are many, many different projects. Every student has their own project that they work on,” says Metzger, who prior to joining Dalhousie worked in Silicon Valley and Germany.
“The story here is that these batteries come in all shapes and sizes.”
Contents of a battery can vary considerably, but there are three main forms on the market: coin, pouch and cylindrical.
Battery shapes are in and of themselves not a mystery. Most automakers use either pouch or cylindrical batteries. What makes each battery unique is the chemistry potential inside.
In one of the Dahn Group’s labs there are several long shelves holding small cardboard boxes. Each box contains 500 battery cells with a combination of letters and numbers scrawled on the outside in black sharpie.
“It’s basically the history of lithium-ion cells back to 2016 when the Tesla project started,” explains Metzger. “I don’t think any other laboratory would have something like that. This is really unique.”
Metzger is open about the goings on in the research group — surprisingly so — but he doesn’t allow photographs of the dead storage boxes. This is because the codes are the chemical compositions of every battery the Dahn Group has worked on for Tesla.
It’s a wall of trade secrets and a roadmap of the Dahn Group’s (and by extension Tesla’s) learnings in the journey to building the best battery.
The best lithium-ion batteries
Metzger is sitting at a table in his sparsely decorated office. He twists around and plucks what looks like four blister packs for hand wipes off a book shelf.
“I would say that’s probably the best lithium-ion cell you can make today,” says Metzger, pointing to the thinnest in the line of blue rectangles spread on the table.
The tiny foil package — which is a battery cell — is two centimetres wide and four centimetres long. It’s 3 millimetres thick.
Inside, says Metzger, is a test-sized “jelly roll” (a method of folding and rolling the anode, cathode and separator together) containing the most successful battery chemistry the Dahn Group has produced for Tesla to date.
The mini pouch cell is the thinnest of the four samples and contains a new ingredient.
“Silicon carbide,” reveals Metzger. “If you put silicon into your negative electrode you can increase the energy density a lot. Even in this small volume you can store the same energy as you can in this thick battery — the lithium-iron-phosphate (LFP) battery.”
But, says Metzger, there is a catch.
The silicon battery (Electric Autonomy knows how much silicon is contained in the battery, but agreed not to report it) does not cycle — that is to say charge and discharge — as well as the LFP battery the group developed.
The LFP battery, Metzger says, is second best out of the four. It’s thicker than the silicon-based battery, but it cycles “super well.”
Meanwhile, the NMC battery in the desk line-up is already famous as Dahn and Tesla’s “million-mile battery.” But, Metzger says, it’s due for a major name change.
“This cell it has now 19,500 cycles [and counting]. Each cycle is 300 kilometres. So, if it were at 20,000 cycles it would be 6 million kilometres.”
That is to say, 3,728,227.15 miles.
Better with age
A nearly four-million mile battery is a seismic innovation.
A battery with a lifetime performance in that range in and of itself is a milestone achievement. But it’s not the only encouraging finding the Dahn Research Group is discovering.
Down the hall from Metzger’s office there is a semi-dark room. Sitting in between a tower of computers and measurement equipment that reaches nearly floor to ceiling is a desktop computer screen showing a well-known equation in physics.
There is a magic number in battery technology: 1.
The 1, Metzger explains over a loud humming that dominates nearly all the lab rooms, represents the optimum coulombic efficiency (CE). This is the efficiency of how electrons and lithium ions move in batteries.
Take for instance the ultra-thin silicon-based battery cell on Metzger’s desk. It has the best energy density for any battery made in the Dahn labs. However, it has poor cycling efficiency compared to other chemistries.
The perfect battery will have a discharge and recharge cycle that, when divided by one another equal out to 1.
It is unlikely, says Metzger, to achieve a perfect 1 CE battery, “But you can get extremely close. And we’re working on it.”
The “working on it” Metzger refers to is the work the group continues to do on the NMC/million-mile battery. What the team are discovering is that over three million miles later the NMC battery is doing the opposite of what the market fears.
It’s not wearing out; it’s actually getting better.
“The nice thing about batteries is that the coulombic efficiency improves over the first couple of cycles,” explains Metzger.
“Unless really bad things happen to the battery in its life the [CE] number will not go down. It will just — slower and slower — go up. That’s an amazing property of batteries that they actually get better and safer over time.”
Right now the CE of the million-mile battery is sitting “incredibly close to 1,” says Metzger. A paper published by the Dahn Group in 2019 pegs the CE at 0.99985.
To the Dahn Group’s knowledge, it may be the highest efficiency reached yet in the battery world.
Lab testing versus real life
So, what “really bad things” can happen to a battery during its lifetime? Well, for starters, it can live in the real world and not in a highly controlled lab setting.
And understanding and accounting for the difference between a lab battery and a real life battery is critical.
To account for all the variables a battery may encounter in its operational lifecycle that could cause it to fail prematurely, the group puts the battery cells through intense stress tests.
These range from putting the battery cells in 100-degree Celsius heat (it turns out that heat is far more detrimental to a battery than cold, says Metzger) to putting them through tens of thousands of charge and discharge cycles.
To do these tests, the researchers rely on a variety of readily available market tools (heated ovens, for example) and some inventions they’ve made themselves.
The centrepiece of the made-in-Dahnland inventions lives in this dim, cool room. In 2013, a well-known pupil of Dahn’s, Chris Burns, was dissatisfied with the time it was taking to do long-term testing of batteries in the lab to see how they would perform in the real world. But there was no tool available on the market to address the problem.
So, Burns, now the CEO of the Bedford, N.S.-based battery technology solutions company Novonix, took it upon himself to invent and then build “an ultra high-precision charger,” explains Metzger.
“It was really, I would say, a breakthrough for battery research. It’s an extremely useful tool for industry. The reason why Tesla wants to work with us is not because of the off the shelf tools that they can also buy. They want access to techniques like this.”
Burns, through Novonix, now sells the ultra high-precision charger in more compact form than the 1.0 version at Dalhousie.
But the inventor spirit remains and the Dahn Research Group is still spinning out new “machines that make the machines” (to borrow a phrase from Tesla CEO, Elon Musk).
Better batteries, bigger problems
Down the hallway and in a different, far brighter room from Burns’ charger Metzger stands beside a row of red metal boxes. It looks half built, but still very complicated.
And it is.
Metzger’s specialty is studying the gas emitted by battery cells during the cycling process. Sometimes battery materials can interact and create a “side reaction,” which makes unwanted gas emissions. These emissions, if high enough, can destabilize the battery and cause it to fail or worse.
Most of the tour, in fact, has been interspersed with Metzger giving rapid fire explanations and scenarios detailing every conceivable angle about the issue of unwanted gas build up.
The short version is gas build up is bad. Researchers, like Metzger, need a tool to measure what the gases are and how much of each is being produced in the battery cell during the cycling process to help them find out how and why this happens and how to solve for it.
Unfortunately, there was no Amazon product available on next-day delivery for Metzger to order. So, he’s spent several years writing proposals to secure funding to build his own gas measuring machine in the hopes of solving his problem.
“It’s called a multi-channel on-line electrochemical mass spectrometer,” says Metzger of his invention. Once operational, the six-chambered machine will use a series of tubes, chambers and magnets to isolate all the gases being emitted from a battery cell as well as measuring how much of each gas is being produced while the cell cycles.
“It is very important for us. We need to understand when the gases are coming out, under which conditions, which temperatures [and] which voltages so that we can fix it. You’re seeing the first one in the world, but we don’t know if it will work,” adds Metzger.
Always room for improvement
There are 118 known elements in the periodic table.
So far, Canada has classified 31 of them as “critical battery minerals.” But that doesn’t mean the purest version of these minerals are the only ingredients a battery will contain.
While science is rules and principles, innovation is an art. Sometimes it demands researchers be able to apply a creative flair to their work.
For instance, says Metzger, traditionally sodium-ion battery cells (a promising new battery chemistry) must be manufactured in a dry room because the active materials can react with the water in the open air. “So, you can imagine how expensive that is to build a facility like this.”
But, in early 2023, one of Metzger’s students, Dr. Libin Zhang, tried adding two per cent calcium to his battery materials to see if he could stop this unwanted reaction in the battery making process.
“The materials were perfectly stable in air for a week. Total breakthrough,” says Metzger. “Now people can make these materials in factories, even if the humidity is a little high, and they don’t need to worry about it. That’s a huge deal.”
And earlier this year, another of Metzger’s students, Anu Adamson, had a major breakthrough after noticing unused cells sitting on shelves, inexplicably, self-discharging.
Why, Adamson and Metzger wondered, would this be happening? The batteries weren’t in use — had never been in use. So, there shouldn’t be any drain on their charge.
The team tested every component in the battery. They finally found that green tape, ubiquitous in battery cells to hold the components together and serving no other function, contains a polyethylene terephthalate polymer.
This polymer reacts with the chemicals in a battery, causing an electrode reaction, which drains the battery. It’s called a “parasitic reaction.”
“We didn’t think it would matter. But these tapes, it turns out, they’re actually quite important,” says Metzger. A simple fix to using a thinner, cheaper tape with a polypropylene adhesive solved the problem.
“That’s something that will be implemented in industry.”
These painstaking discoveries — adding calcium to battery materials to stabilize them and discovering a work around for the unwanted green tape polymer reaction — stand out as once every two- or three-year highlights in Metzger’s line of work.
And that, for Metzger, is the motivation to keep tinkering and tweaking, molecule by molecule sometimes, for that chemistry sweet spot that will yield the ideal battery.
“I wanted to do something where I can have impact on climate change and do something useful. We need to electrify everything and we need to do it by 2050, otherwise, we’re screwed,” says Metzger at the end of the two-hour tour.
“It’s a very shocking thought to me, but in 2050 I will be 65. I’ll go into retirement. So then at that time, you know, if I have made a good contribution to the field, I think then I will be happy.”