One of the anomalies of the modern battery-powered electric vehicle is how much, save for their tailpipe emissions, they resemble the muscle cars of old. For one, compared with all their “normal” gas-powered equivalents, they all have oodles of torque and accelerate like the proverbial bat out of Hell. They are also — oh, what is the polite term I’m looking for? — fat as f$#@ and desperately in need of a diet.
The battery-powered cars’ problem, as has been detailed ad nauseam, is the batteries themselves. Eighty kilowatt-hours of lithium-ion, a middling amount amongst North American EVs, weighs nigh on a half-a-ton. Build in enough kilowatt-hours for even modest “road-trip” range and you have a vehicle — it doesn’t matter if it’s a sedan or an SUV — that is significantly heavier than its fossil-fuelled equivalent.
It also doesn’t take an engineering degree to understand that weight is as much an enemy to a battery-powered car’s range as it is to an ICE-powered vehicle’s fuel economy. The difference is that, so far, the only solution to inadequate range has been a bigger battery, which, of course, makes the vehicle even heavier, which means that the increase in range is never, ever commensurate with the increase in battery capacity.
In perhaps the most gratuitous example of lithium-ion wasted, GMC’s Hummer EV sports the EV world’s biggest battery — nearly twice as large as other fairly serious electrically-driven sport-brutes — yet, in real-world testing, it barely squeezes out 10% more range. And, no word of a lie, its 212 kilowatt-hours of lithium-ion weigh more than an entire Honda Civic.
The answer, then, is more efficient batteries. In engineering terms, this means increasing their energy density, more specifically squeezing more of those kilowatt-hour things out of each kilogram of lithium-ion, or whatever cell chemistry your future EV might use. Make those batteries more energy-dense, and the same-sized battery can eke out more range without increasing weight. Or, if you maintain the same kilowatt-hour rating, the battery can be made smaller — and hence, lighter — improving energy efficiency. Either way, the battery industry’s Holy Grail — energy density — is all about the weight.
And thus do we come to one of the major topics of next week’s Driving into the Future panel, Battery Tech in the Spotlight — that’s February 12 at 11:00 a.m. — when Michael Pope, an Associate Professor of Chemical Engineering at the University of Waterloo; and Dr. Euan McTurk, Consultant Battery Electrochemist at Plug Life Consulting, will try to bring us up to speed on the developments in the battery-electric pipeline. Here’s just a smattering of what they’ll discuss (with a lot more exactitude than my own).
Solid-state batteries
Beyond all the hype — Honda has intimated its upcoming solid-state batteries could boost EV range to 1,000 kilometres; so has Toyota — here’s the real measure that will really determine the worth of future batteries. According to Automotive Manufacturing Solutions, the current low end of EV batteries — the lithium-iron-phosphate (LFP) cells that Chinese automakers squeeze out so cheaply — manage about 160 watt-hours per kilogram. Nickel-manganese-cobalt combinations, meanwhile — the more expensive formulations used by most Western automakers — are good for about 250 Wh/kg.
The reason there’s so much hype behind solid-state batteries is the claim the not-so-simple change to a solid electrolyte will boost their energy density to as much as 400 Wh/kg. That’s a 60% bump, which, to the average EV owner, means a similarly-sized (physically) battery should be able to propel the same EV 60% further.
Toyota also claims a solid-state battery can be reliably fast-charged from 10% of capacity to 80% in just 10 minutes. That would, of course, also require even more powerful charging points than the 350-kilowatt versions so rare on our streets today, not to mention the improved transmission infrastructure that we’ve long been promised. Nonetheless, if not quite the end of range anxiety, it might at least the beginning of the end.
Cell-to-body batteries
Another approach, perhaps even more difficult to mass-produce — and understand that some automakers have been working on solid-state batteries since around 2010 — is cell-to-body batteries. Rather than focus on improving the energy density through battery chemistry and cell structure, they simply try to reduce the weight of the casing. Or, in extreme cases where the casing becomes the body, essentially eliminate the ‘container’ completely.
As McTurk told the World Economic Forum, “integrating cells into the chassis allows the cells and the chassis to become multi-purpose. The cells become energy-storing and structurally supporting. This effectively cancels out the weight of the cell casing, turning it from dead weight into something valuable to the structure of the vehicle.”
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But while Tesla, BYD, and CATL (China’s Contemporary Amperex Technology Co., Limited) are all looking into this technology, perhaps the world’s leading proponent is Chalmer’s University of Technology in Sweden. They have developed what they call “massless energy storage,” their battery being made of carbon-fibre. Carbon-fibre is, of course, extremely lightweight and incredibly strong, which is why pretty much every supercar chassis of note is built from the lighter-than-aluminum weave. What the Chalmers team, led by professor Leif Asp, has discovered is that it is also an effective electrode material.
What’s most interesting about Asp’s battery is it only produces 30 Wh/kg, a far cry from the energy density of current batteries, and less than 10% of what the best solid-state packs are expected to produce. But, according to the research team’s official press release, “when the battery is part of the construction and can also be made of a lightweight material… not nearly as much energy is required to run an EV.”
Asp says he’s done some calculations that show they could drive “up to 70% longer than today if they had competitive structural batteries.” Now, such a body shell might run into all manner of problems, such as cost issues, recycling challenges, and severe consequences following a collision, not to mention insurance and repair problems. But, with weight and energy density the most important criteria for the future’s electric vehicles, there can be no denying that structural batteries are an attractive alternative to those looking to lightweight EVs.
LMFP batteries
We’ll be discussing other battery technologies in our Driving into the Future panel as well. Lithium-sulfur, sodium, and even metal-air batteries are on the table, this last some truly Space-Age stuff. All are worthy of the research being devoted to their formulation, but are even further out in their development cycles, given how long it has taken to get solid-state into — or nearly into — production! They aren’t quite ready for the here-and-now.
One unexpected twist that might make a more immediate difference is LMFP chemistries, which see more manganese added to the iron cathode in lithium-iron-phosphate batteries. The result is a small but significant boost in range — energy density is estimated by Mitsui Global Strategic Studies Institute to be 10% to 20% better than LFP — with little price increase to what are already the cheapest batteries used in electric vehicles.
This last is made all the more significant to North American vehicles because these lower-cost batteries are becoming more popular here — some Tesla Model 3s sold in Canada are powered by LFP, as are some Ford F-150 Lightnings and Mustang Mach-E SUVs — and, for sales growth to increase as projected, EVs must become not only more efficient, but also cheaper.
Next Wednesday, our Battery Technology in the Spotlight experts will be detailing all these new battery technologies — and more! — and I can assure you both McTurk and Pope can explain their construction and benefits far better than I. Click here to register for the latest Driving into the Future panel on February 12 at 11:00 a.m.
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