Back in 1925, long before the X-Prize foundation even existed, an inventor by the name of Sakichi Toyoda reportedly offered a prize of 1 million yen for the invention of a battery that would produce more energy than gasoline. As you can probably guess, no one has claimed that prize yet. However, Toyota thinks this target may be possible in the future and thus created, in 2008, a research division to work on "revolutionary batteries." Three years later, this division has been giving technical presentations on batteries that have breakthrough energy density levels. This is especially intriguing coming from a company that still uses NiMH batteries in its current-gen Prius.

Current lithium-ion batteries top out at an energy density of around 620 Wh/l (Watt hours per liter) and have a theoretical limit well below the energy density of gasoline. But there's more to advanced automotive battery technology than li-ion. Toyota believes solid-state batteries will have the capacity of over 1000 Wh/l and metal air batteries would at least double that figure again. While those are amazing numbers, the energy density of gasoline is closer to 10,000 Wh/l, so we are not exactly sure how Toyota plans to get to Sakichi-level batteries. Will his prize go unclaimed for 100 years? Also, does it really need to be reached for plug-in vehicles to take off?

While setting lofty energy-density goals is great and all, what really needs to come down is cost. The main reason cars like the Nissan Leaf don't have larger batteries is money. Engineers can always design around obstacles like a heavy or large pack, but there's not much they can do if the pack costs $50,000 dollars. Not yet, anyway.

[Source: Plugin Cars | Photo: Jonas Dalidd]


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    • 1 Second Ago
  • 26 Comments
      Dan Frederiksen
      • 3 Years Ago
      lower price is certainly possible, even today. they are holding back the price because they can. short sighted but that's their choice and clueless govs don't understand they need to force that issue. you get an F Steven Chu. double or triple the density of state of the art would certainly be nice too. not strictly speaking necessary but would certainly help (if safe) it's not true though that the leaf pack is only limited by cost. the pack already weighs 300kg. that's partly poor engineering though, it could easily weigh only 200 but that's still a lot. and weight begets weight. you can't just pile 600kg in a car and not expect to pay dearly for it. with the current primitive steel structures I'd guess that for every kg you need to carry you pay another kg in structure to carry it. maybe much more. remember that the Leaf is a fat ass already at disgusting 1700kg. a good 4 seater design will probably have around 130kg battery with today's tech. with future tech you might even lower that a bit although you'd probably mostly just gain the added range. not much is gained by making the battery weight negligible compared to the passangers
      DRAGON
      • 3 Years Ago
      Gasoline is about 10'000 Wh/L BUT the best car gas engines gets 30% efficiency, meaning that 70% of these 10'000 Wh/L are wasted, meaning that 3'000 Wh/l are used to move the car for real. Best electric car systems gets, let's say 90% of the 620 Wh/L Li-ion top technology, meaning that 558 Wh/L are used to move the car... Gas still does more than 5x better that the best electric (meaning expensive) technology...
        Ford Future
        • 1 Day Ago
        @DRAGON
        An EV only uses coal if it has to. Guess what's happening in Heat-Wave-Climate-Denial Texas? They're shutting down coal plants, because it's too hot. Guess how they're getting their power: Wind. EV's - Keep pollution out of your garage, and your neighborhood. - Keep your money in your local economy, allowing your utility to upgrade equipment, creating jobs, jobs that you might need. Or you could send your money to the Saudi's. But, they hire from Indonesia, so you're not getting a job.
        GoodCheer
        • 1 Day Ago
        @DRAGON
        30% efficient at optimum rpm and power. In a drive cycle, the way a real gallon of gas is likely to get used, you'd be very luck to get 18%, and some engineers I've talked to derive average conversion numbers more like 12%. You point still holds, but by not as much.
          Timo
          • 1 Day Ago
          @GoodCheer
          @Dragon, that ABG has got one thing wrong: best battery energy density. That's around 600Wh/kg not 600Wh/L, for volumetric energy density we are already going beyond 1000Wh/L, those are just not yet in large scale mass production and cost a lot. It wouldn't surprise me to find batteries in next few years to surpass 2000Wh/L and 1000Wh/kg. 2013 Panasonic 18650 4Ah batteries have about 800Wh/L energy density, and that one _is_ large-scale cheap mass-produced product. Twice the capacity of Tesla Roadster battery. That's also first mass-produced battery I have heard that switches from carbon anode to silicon anode, and silicon anode is the chemistry where potential energy densities skyrocket.
          DRAGON
          • 1 Day Ago
          @GoodCheer
          Yeah, you're right, but still at 12%, a gas powered car gets 1'200 Wh/L, more than twice of the best (and expensive) EV. Hopefully EV tech will improve in the future. Another point is about electricity production. I don't know where you live but in the US, 68.3% of the electricity comes from coal+gas... Of course if you lived if France the problem is not the same. There, EVs make sense right away. Their electricity comes from nuclear+renewables at 90.4%!
      Jim McL
      • 3 Years Ago
      A fair comparison would be between a battery and gallon of gasoline PLUS a compressed air tank holding the oxygen needed to burn the gasoline PLUS a tank to hold the exhaust, instead of poisoning the commons with exhaust. Now how does the energy to weight ratio look? Now if you want to compare gasoline to air batteries, fine but you still need to add a tank to hold the exhaust from the gas engine.
      EV News
      • 3 Years Ago
      It's a misinterpreted aim or it's a pointless goal. EVs are so much more ENERGY EFFICIENT than a petrol powered ICE vehicle that they can use as little as 1/10-20th the energy. The battery in a Nissan Leaf holds the energy equivalent of just 0.65 US Gallon of gasoline yet can travel 100 miles on that. The recently launched SIM-LEI with direct drive wheel motors is TWICE as energy efficient as the Leaf so can travel over 200 miles on that same 0.65 US Gallon equivalent amount of energy. If a battery was developed with the same energy density as gasoline, the Leaf could travel over 2,400 miles on a 13 gallon tank (the ICE version of the Leaf, the Versa, has a 13.2 Gallon fuel tank) and the SIM-LEI would have a range of 5,000 miles on a single charge!!! Your average motorist would be carrying around enough energy to cover 6 months worth of driving???? Pointless!! And who's trying to claim a Leaf battery costs $50,000??? That ridiculous!
        DRAGON
        • 1 Day Ago
        @EV News
        Well, there is nothing misinterpreted or shady goal....just a scientific fact: even with the very good efficiency of an electric system, gas is still far ahead...
      2 Wheeled Menace
      • 3 Years Ago
      In the last 2 years, i have seen cells available to the public go from about 160wh/kg to 200wh/kg, with 220wh/kg+ on the horizon. I think an affordable 200 mile EV is only a few years away. Hell, the Tesla model S is going to do up to 300 miles.. insane.
        • 1 Day Ago
        @2 Wheeled Menace
        Yes, but the battery pack weights nearly half a ton to go 300 miles. More batteries = more weight = more distance.
          Ford Future
          • 1 Day Ago
          Half a ton is 1000 pounds. I think they only weigh as much as your girlfriend, 300 pounds, Drum Crash! Thank you, I'll be in town all week.
      • 3 Years Ago
      Considering that theoretical energy density falls abit short of that with gasoline, lithium-air has rather equal practical energy density. With that in mind, there's still some real difficulties that needs to be overcome. In the past year or two, li-air battery in a lab was expected to reach 2 kWh/kg and 2 kWh/L, but only 400 W/kg and 500 cycles. I think they resulted with only 100 cycles before the capacity dropped to 50 %. Probably in the current decade li-air can reach many of its targets. After all, a decade earlier there was usually only 1-5 cycles before capacity was almost completely gone.
        2 Wheeled Menace
        • 1 Day Ago
        Imagine, however, if each cycle gave you a thousand miles? WIth the substantial decrease in size, more amp-hours ( or kilowatt-hours ) can be fit into the same space. I am surprised that lithium air has came that far - i remember the 1-5 cycle problem and didn't know they have improved, that's impressive.
      harlanx6
      • 3 Years Ago
      The market will make the decision of which is better if the governments don't get in the way. Batteries will get better, but ICE engines will also get better. Electric cars are a quaint idea, as long as we aren't burning carbon to produce the electricity. Still, I'll take a Prius over an EV every time, even with NiMH batteries.
        sirvixisvexed
        • 1 Day Ago
        @harlanx6
        But from that viewpoint, all electricity use pollutes.....phone, computer, vacuum, dishwasher, clothing washer and dryer....etc. What makes the car unacceptable for such use but everything else unquestioned?
      Hyns
      • 3 Years Ago
      I'm not expert or anything but, gasoline is closer to 10,000 Wh/L minus energy use to pump, transport and refined into gasoline will leave you with what?
        NIC123
        • 1 Day Ago
        @Hyns
        They're talking about the energy density of the gasoline that's sitting in your fuel tank, not of the potential energy in crude.
      Spec
      • 3 Years Ago
      You do NOT need energy density on par with gasoline since electric motors are closer ~85% efficient whereas gas engines are ~25% efficient. Also, electric motors are much smaller thus freeing up more room for batteries. And with electric, you can recoup energy while braking and put it back into the battery. We all want better and cheaper batteries such that all technological battery advances would be very welcomed. But the technology that exists today is good enough for the job as the Leaf and Volt have proven.
        Smith Jim
        • 3 Years Ago
        @Spec
        Great post, Spec. You hit the nail right on the head.
        2 Wheeled Menace
        • 3 Years Ago
        @Spec
        I'm sorry spec, but that's not entirely true. 100 mile range is not going to cut it for the public, try 200-300 and you'll see people not thinking twice if they have the means to go electric.
          Ele Truk
          • 1 Day Ago
          @2 Wheeled Menace
          Alas, I think that is true. However, currently because EVs are in short supply, none of the EV manufacturers are really doing anything to educate the general public as to how many miles they actually need. Once there is actual competition in the market for EVs, we may see a different trend in the EV advertising. For now, most of the general public expect EVs to have to operate exactly the same as their gas counterparts. But as it stands right now, most new Leaf owners learn about the differences by owning the vehicle, not by anything they have read or seen in advertising. A better educational ad campaign will be necessary once dealers actually stock EVs on their car lots.
        Marco Polo
        • 3 Years Ago
        @Spec
        @ Spec. Theres no disputing what you say is true. But Toyota should be congratulated for pushing the boundaries to the limit. If Toyota are rich enough to devote a relatively small amount of R&D funding to set up a research division to expand the outer limits of battery technology, why not? When Gotlieb Daimler first invented the Internal Combustion Engine, it sparked a million innovations, and improvements, over the next hundred years. Batteries powering the Leaf and other EV's are very primitive. The one ingredient holding back the adoption of the EV (and always has been) is the inadequacy and cost of the energy storage system. Persuading people to change their lifestyle to fit in with a particular technology, is always going to be more difficult than providing a superior technology that enhances their chosen lifestyle.
        JP
        • 3 Years Ago
        @Spec
        Sort of. Yes they are technically good enough, but they are too expensive. Higher energy density means more capacity with less material, which should translate into lower prices. For EV's to really become a viable option prices do need to drop. Not as much as some people would suggest because I don't think EV's need to be as cheap as gas cars since their operating costs are lower and they have the potential to last much longer than an ICE vehicle.
          • 1 Day Ago
          @JP
          People still have to be able to afford the down payments, and if a car costs 40 grand instead of 20, you're limiting your market considerably.
        spw
        • 3 Years Ago
        @Spec
        good enough for what? for niche market maybe...
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