Published on June 28th, 2020 | by Guest Contributor
How Batteries Work, How They Fade, & Why So Much Buzz Around Tesla Battery Day (Video)
Originally published on EV Annex.
By Eli Burton
According to Elon Musk, Tesla’s much-anticipated “Battery Day” will be combined with the company’s Shareholder Meeting on September 15th. To learn more about batteries before the big day, I spoke with Ravindra Kempaiah recently about his thoughts relative to Tesla and potential battery improvements that might be revealed soon.
Ravindra Kempaiah is a materials scientist and PhD candidate at the University of Illinois–Chicago working on electrode materials for his thesis. Apart from his research, he’s an electric vehicle enthusiast and entrepreneur in the electric bike space.
Before that, Ravindra obtained his MSc in Chemistry & Nanotechnology from the University of Waterloo in Canada in 2011 working on graphene and MSc in Chemistry from the University of Maryland–College Park while working on nano composites and liquid crystals.
Now, at the University of Illinois–Chicago, Ravindra’s work involves computational studies of lithium kinetics in transition metal oxide cathodes. He will be moving to Halifax, Canada, after his graduation later this year to continue his battery research.
Here are a handful of key takeaways from our conversation that could help EV enthusiasts gain an increased understanding in battery technology — a key to the future of electric vehicles.
What Maxwell Means for Tesla
Maxwell, a company Tesla recently acquired, has a technology to create cathodes without using toxic solvents. As a result, there are less chemicals impeding the flow of the lithium-ions between the cathode and anode, allowing them to move back and forth faster. This allows for higher rates of acceleration and a faster potential rate of charge.
Why Batteries Degrade
Lithium goes back and forth between the anode and cathode, and after 30–40 cycles, the outer layers begin to decay. The cathode material begins to lose its structural integrity because as the ions go in and out of their storage channels, the nickel cycles between oxidation states and begins to crumble. Over time, lithium loses the ability to go between certain spaces, resulting in permanent range loss.
Many factors go into the long-term health of your battery. Temperature plays the biggest role, very high temperatures are exceptionally damaging to the battery. Very high temperatures cause the “hive” to degrade faster. On the other hand, a very cold climate helps preserve the long-term structure of the hive, but it’s bad for charging — a very cold battery should be warmed up before charging to avoid significant damage. To put this in perspective, if you leave your Tesla sitting (unused) for three weeks outside in a Minnesota winter and you suddenly try and supercharge it, “bad” reactions could occur within the cells. In turn, this could potentially damage your battery.
Power Fade vs. Storage Fade
There are two types of potential loss in batteries: voltage fade and power fade. Lithium ions can get trapped in undesired reactions and stick to the surface of the anode or cathode, becoming permanently unusable. If the hive crumbles and you lose storage, that’s considered “capacity fade” by industry observers. On the other hand, there is “power fade” when there isn’t much lithium going back and forth — making it hard to get energy out of the cell.
The best way to think about the relationship between lithium-ions and the anode and cathode is that of a bee in a beehive.
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When Will We See a Solid-State Battery?
According to Ravindra, a solid-state battery is a fantastic concept, but it’s still 5–6 years away from commercial scale. In theory, a solid-state battery is extremely safe, because you remove the (currently used) liquid electrolytes and put in solid electrolytes making puncture not a risk for fire. The problem? Lithium-ion has a difficult time moving through solid electrolytes versus liquid ones. The other challenge is the cost. Really rare materials — including lanthanum, zirconium, and silver (in some cases) — can be required to make an effective solid state battery. Currently, there just aren’t enough of these materials available for it to be practical on a commercial scale. Toyota has been working on this since 2010 and it still doesn’t have a cell that is economically viable.
What Makes Tesla’s Batteries So Advanced?
Tesla’s industry leadership, over the years, comes down to a cumulative effort (more on this below) — gained as a result of its vertical integration. Tesla controls what kind of minerals it gets and then it knows how to build cells, modules, and packs from those. As a result, Tesla can optimize every step in the chain. In contrast, GM (and other legacy automakers) don’t have this level of control. In turn, they tend to buy packs from LG Chem, CATL, SK Innovation, and others and simply put it together.
Tesla has the opportunity to innovate and engineer its batteries in order to specifically optimize their performance and longevity for Tesla’s cars. And it doesn’t stop there. Tesla is also working on its own anodes, cathodes, electrolytes, and cell-to-pack technology. In addition, Tesla has Maxwell and Hibar to make more efficient manufacturing — it’s a comprehensive cumulative effort that differentiates Tesla from others entering the EV space.
For a deeper dive into batteries, check out our interview with Ravindra below …
Video: Tesla Geeks Show; Guest Contributor: Eli Burton is proud to be friends with the Real Life Starman and just attended the recent SpaceX launch. He is also President and Founder of the My Tesla Adventure Tesla Owner Club. Eli is also co-host of the Tesla Geeks Show podcast and creator of The Adventures of Starman comic book series.