Lithium-based batteries aren't the only ones that hold promise. Donald Sadoway, an MIT professor who has teamed up with Bill Gates on a storage battery for grid applications, is also working on an aluminum-ion chemistry for EVs. The aluminum battery, which employs a solid polymer electrolyte, is probably the most novel idea on the battery horizon -- and possibly the riskiest. But Sadoway told us he sees tremendous potential: 500Wh/kg at $100/kWh.
"Aluminum is the third most abundant element in the earth's crust, 8,000 times more abundant than lithium, and available in the US," he said. "This means cheap raw materials and a secure supply chain."
Back to the future
Not all solutions are targeted at the distant future. Energy Power Systems (EPS) is reaching back to the age-old lead-acid chemistry in its effort to change the future of the EV. Instead of developing a high-energy battery and then reducing the cost, the startup is starting with low-cost lead-acid chemistry and then adding power density and life.
Subhash Dhar, who has notably served in executive roles with Energy Conversion Devices and Ener1, founded EPS with the idea of developing a battery with the same power density as nickel-metal hydride at about a third of the cost. Right now, his battery appears to be one of the strongest short-term solutions. It reportedly offers about six times the power density and almost 10 times the life of traditional lead-acid, and it does so for about $100/kWh -- a figure that's little more than a dream for most EV battery companies.
The concept has always been to start with a chemistry that gives you high energy density, and then hope you can reduce the cost. But the industry has never made much progress in terms of cost. So we turned it upside down -- we started with low cost and improved the technology, so we can get the performance without disturbing the cost structure.
In truth, the EPS battery doesn't offer traditional high performance. Its energy density is 40Wh/kg -- a tiny fraction of what lithium-based batteries offer. But Dhar said he isn't worried. He anticipates the battery being used in full hybrids, mild hybrids, and start-stop applications, where power density matters far more than energy density. He also foresees it employed in plug-in cars, in tandem with lithium-ion batteries. Using Dhar's setup, the lithium-ion battery would supply the range, while his lead-acid design would produce the power. The bottom line, he said, is automakers might be able to build hybrids and plug-in cars for less money.
Patience required
Most people aren't ready to make the transition away from lithium-ion. Many say lithium-ion costs will drop sharply in the coming decade, possibly hitting $250/kWh for EV battery packs and $150/kWh for cells by 2025.
Still, boosting energy density may be a more difficult task. Despite claims by US Energy Secretary Steven Chu that energy density will double or triple while battery costs drop 50 percent in the next three to four years, many in the battery community are doubtful.
Most experts say that the wait for $5,000 batteries and 300-mile ranges will be a long one. History has shown that battery development often takes 20 years or more of serious, well-funded effort, they say. "It can take a very, very long time to bring research in the lab to a strong commercial position," Cairns said.
That's why most material scientists are openly rooting for lithium-ion to succeed, even if lithium-ion is a competitor. "We want to see lithium-ion be successful," said Kopera of Sion Power. "It paves the way for our higher-energy batteries down the road."
Cap'n, I read this article with interest. While doing so I looked up a number of things. What I found was suprising. One comment you made was the search for a $5K battery pack that got 300 miles of range. Tha is a long way off, as you mention.
With a gasoline engine at 23 mpg (see below), the 300 mile range translates to 13.04 gallons. The weight of the gasoline is 72.88 lbs. Tesla claims that range for their Tesla S with the 85 kW-h battery. The weight seems to be about what the roadster's is at a minimum. That would be 900 lbs. The ICE gets 0.26 lbs./mile, while the Tesla S has a rating of 3 lbs./mile. So, the first thing that needs to be addressed is the weight of the battery. The Tesla S battery has density of 94.44 W-h/lb. This is at the high end of the range you quote for current batteries (note the unit difference).
What is even more interesting is that the curb weight for a Tesla S is 4,647.3 lbs. That's a lot. The roughly equivalent BMW 5 series sedan (which Tesla is targeting with the S) is the 550i sedan. The power output is similar, The BMW weighs 4,365 lbs. I find this very interesting for both given all the articles and discussion on weight saving, etc. that the car manufacturers are supposedly working on.
You're right, Naperlou. You are essentially saying that the specific energy of gasoline is far higher than that of a lithium-ion battery. And, yes, that's a drawback. It's also a drawback when the battery's charge is depleted. The 900 lb battery still weighs the same. It still has to carry its own dead weight, whereas the weight of the gasoline in your example has gone from 73 lbs to zero when the gas tank is depleted.
Chuck, that's a good point. I like to let my car run down to empty, if I am in an area with lot's of gas stations, becuase it will get slightly better mileage toward the end of the tank. Another thing to note is the difference weight of the engines. I don't know what the Tesla S engine weighs, but I was told that the Tesla Roadster engine weighs only 70 lbs. Add to that the fact that there is no transmission, and the S engine has to weigh a lot less than the 550i engine.
One thing this makes clear is that when comparing two very different technology systems one has to consider more than the core part of the system. In this case the motors are vastly different and just comparing them would leave you to believe that the electric car should be lighter. Add in the energy storage system, and you come up with a very different story.
Nice new picture, by the way, but they cut off the top of your head.
Chuck, while the payoff for new battery chemistry may be years away, it's good to see this deep research going on. There is a ton of common technology that wouldn't exist now if not for the deep, raw research.
I agree, Rob. If EV battery chemistries are going to come remotely close to what gasoline already gives us, this is the way it will happen. The people I spoke to said we have to be ready to move beyond lithium-ion, and the ARPA-e program is a great way to start doing that.
I agree, Chuck. The lithium-ion battery seems to have hit a wall. But who knows. In the time it takes for a battery based on alternative chemestry becomes feasible, the lithium-ion battery may have sacled its wall.
It stands to reason that any improvement in battery energy density technology will first be applied to less demanding applications, such as mobile computing and communication devices, and only later scaled up to the kilowatt range demanded by transportation. In fact, the technology might not prove to be scalable at all.
It would be interesting to hear from the environmentalist 9green) lobby if it turns out that the only method of improving EV technology involves toxic materials (such as lead-acid). Would it be banned in California?
It would be interesting to hear from the environmentalist 9green) lobby if it turns out that the only method of improving EV technology involves toxic materials
Little about any EV is "green". When you factor in all that goes into raw materials (plastic, metal, rubber, electronics), fabrication, energy storage, operation/maintenance and disposal (plus the roads they're driven on) all vehicles are a messy proposition. EV's are the great fallacy of green initiatives. If it were up to the enviroweenies we'd all be driving these:
@Contrarian - Be prepared for news headlines like "heavy rains and flooding take toll on cardboard bikes". Will be drying the bike for a long time to use it as fuel to keep warm over the winter nights.
The one comment given that the Lithium-Sulfur battery could be looking at a vehicle life of 150K miles seems really short sighted to me. Many vehicles today break 200k or even 300k without major repairs.
Interesting article.
More than anyone else I've read Charles, you have convinced me (through the data presented) that a commercially viable, high volume, EV is still quite a way in the future.
Good point, Dennis. I drive a car with 175,000 miles on it and I believe it's got at least another 75,000 left. My son drives a car with 190,000 miles on it. Average vehicle life has soared over the last 20 years. Regarding high volume EVs: You hit it on the head. The key lies in your use of the words "high volume." Pure EVs are great, fun vehicles to drive, but the average consumer can't afford a second car that costs $30,000 to $40,000. Until higher energy batteries are readily available and until cost drops, pure EVs will see low volumes.
First, we need to acknowldge that Moore's law only applies to the manufacturing technology side of product advancement. What batteries need now is a discovery of additional physics and chemistry functionality. So the advances are not guarranteed. The other challenge is that even after discovering some combination that will provide some mechanism for greater energy storage, it will still need to be made durable and inexpensive and cheap to manufacture. Just because something works in a simulation model, or even in a laboratory, does not mean that it can ever be practical or producable. Reality can be so very harsh.
It really would be very funny for some fantastic battery technology to be developed, and then have it forbidden in the state of california because it was "toxic". Actually, it might point out the folly of letting emotions run your show. I would certainly be one to laugh loud and long if it happened.
Charles, I agree completely with you on this point. I'm driving a Toyota Pre-Runner and I cannot justify an EV at $40k as a replacement. I have a 74 mile round-trip commute every day to one client. Right now, until the industry can generate more miles between charges and bring down the purchase price, an EV is just not in my future.
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