Toyota Seeks Battery That Stores More Energy than Gasoline

By · August 03, 2011

Today’s electric cars have batteries that offer about 100 miles of range on a charge. That, critics say, is the reason electric cars don’t compete with gas-powered vehicles and never will. Yet, those critics assume that technology stands still and overlook the potential of emerging battery technologies that could rapidly expand the range limitations of electric cars. You might laugh off claims of major battery breakthroughs coming from a garage tinkerer or start-up company—but none other than Toyota has recently been presenting technical papers about quantum leaps in energy-storage capacity.

The fact that Toyota researchers have been talking about next-generation battery technologies is significant for a few reasons. First, the company is better known for last-generation batteries for electric-drive cars—namely nickel-metal hydride that continues to power Toyota’s hybrids. Second, Toyota has been among the most reluctant to offer plug-in cars—only really jumping in with both feet with last year’s tie-up with Tesla. Even today, the company continues to emphasize that plug-in cars with small batteries are a better route than big-battery EVs. Yet, if we can believe the numbers displayed on one particular graph that Toyota researchers continue to show at technical conferences, then batteries won’t need to be very big to offer a driving range similar to gasoline vehicles.

The race to the Sakichi battery

The race to the so-called Sakichi battery

The above graph first surfaced in 2008, when Toyota established a research division to work on “revolutionary batteries.” At that time, the company talked about a “Sakichi battery,” named after Sakichi Toyoda, the inventor of Japan’s first power loom. He is sometimes referred to as the father of the Japanese industrial revolution. In 1925, Sakichi reportedly set out a (yet-to-be-claimed) prize of 1 million yen for the invention of a storage battery that would produce more energy than gasoline. Toyota’s goal is to make the Sakichi battery very durable and very quick to charge.

Persistence of Vision

Three years after establishing the research division, Toyota continues to show the graph. In fact, it was shown by Hideki Iba, general manager of Toyota battery research, at Third EV and HEV Drive System Technology Expo in Tokyo on Jan.18-20 of this year. Then, on May 18, 2011, (relatively soon after the devastation earthquake), Toyota’s Takeshi Uchiyamada, executive vice president, appeared at First International Electric Vehicle Technology Conference 2011 in Yokohama, where the slide popped up again.

The graph reveals that Toyota is focused on moving beyond lithium to solid state and metal air batteries. What jumps out at me is the X axis for energy density: As soon as you cross the “limit of conventional batteries,” and move into solid state technology—replacing the electrolytic solution in lithium-ion batteries with a solid—the energy density per liter increases by a factor of 10. Metal air takes energy storage even further in the direction of a Sakichi battery.

Is it time to start imagining a 100 kWh battery fitting into the same space as today’s battery? Or at least a battery that could offer multiple hundreds of miles on a charge in an even smaller package than what you see in a car like the 2011 Nissan LEAF?

Maybe not quite yet. It could be another decade or more before we move into the Sakichi era. But today’s electric cars already provide what typical U.S drivers require—while delivering a brisk enjoyable ride. With Toyota and other companies breathing down the neck of a battery breakthrough—whenever it does happen—we could push the range of electric cars from today’s 100 miles to multiple hundreds of miles. I can’t wait to see that day, and to see if such a development would finally silence the loudest critics of electric cars.


· · 7 years ago

There are really measures of energy density, energy per unit volume, and energy per unit mass.

GM did testing on zinc air batteries in the 1970s, but as I understand it, they couldn't really be recharged in the normal manner of just plugging in. They are used for hearing aid batteries now. GM is now working on Lithium Air batteries that they hope to commercialize in the next 10 years.

The U.S. DOE has awarded over $34 million in grants last year for advanced vehicle battery technology, including two grants for Lithium Air battery proposals, and others for Magnesium-ion, Zinc-Air, and a novel "All-Electron" battery being developed by Stanford University in partnership with Honda and Applied Materials, Inc.

· Dave K. (not verified) · 7 years ago

The limits have certainly not been reached, but lithium manganese and lithium iron phosphate are certainly good enough. I would even argue that nickel cadmium was good enough, at least for a PHEV, and we had those in the 70s. Once we have a robust EV industry battery technology will improve, but we have to start with what we have.

· · 7 years ago

I'm a little confused by the title of this article. Nowhere in the chart is a battery that comes close to the energy density of Gas which is about 10,000 Wh/L and 13,000 Wh/kg. The best battery on this chart (metal air) is 1/3 the Wh/L of gas implying a volume of 3 times a gas tank to store more energy. Batteries of similar size are already harder to package efficiency (because of shape restrictions) let alone one that is 3 times the volume. Don't get me wrong, these batteries are a huge improvement, getting the energy density within an order of magnitude of gas, but they don't beat gas as implied by the title of the article.

One more note. What is not discussed is the energy cost density (Wh/$). In addition, these batteries need to retain the energy density over 10 years, 150k miles. I don't know enough about the energy over life of these batteries to answer this. Does anyone else know this?

· · 7 years ago

Some who follow battery technology closely seem to think that the next evolutionary step in standard lithium battery technology will find silicon replacing carbon in the anode. Large scale production of these is supposed to ramp up by around 2013 . . .

The newly introduced BMW "i" cars are using something called nickel maganese colbalt, made for them by SB-Limotive . . .

The one I'm really fascinated with, though, is lithium vanadium phosphate (LiVPO4.) This is what we saw Germany's DBM test inside modified Audi A2s over this past year . . .

Unlike all the other lithium batteries, where dry or semi-solid substances are stacked or rolled together inside a tube or pouch, the LiVPO4 is what is referred to as a flow battery . . . liquids pumped into and out of the main chamber that contains solids. One can think of it as a sort of fuel cell . . . but one in which the ingredients are continually recycled instead of consumed. That last statement may not be absolutely accurate in a pure technical sense but, perhaps, this illustration will explain it better . . .

The neat think about flow batteries is that they can be scaled up considerably (think something the size of a railroad shipping container) and used to store megaWatts of grid-connected power, generated by very large solar or wind arrays. Scale it back down and it fits inside a car . . . with greater energy density than today's conventional lithium batteries.

· · 7 years ago

A couple more things to consider:

1. In terms of pure heat when burned, gasoline produces about 9.65 kWh per liter. However, turning that into usable electricity requires throwing away roughly 80% of that energy, leaving you with about 2 kWh/liter. You then need to factor the size of the gasoline tank, engine, generator, exhaust, etc. Once you do that, depending on the all the specific details, you may find that solid and air batteries are better. (Sakichi will definitely be better but at this point, it's more of a mythical thing.)

2. The liter figure determines the range more than the kg figure. One-hundred liters of battery can be designed easily in a normal car. Nissan LEAF has 48 modules that measure 2.55 liters each so it has 122.5 liters. With 24 kWh capacity, that equates to nearly 200 Wh per liter. According to the Toyota graph, the new technologies could push things to the 1,000 Wh per liter level.

· Verily EV (not verified) · 7 years ago

'regman' makes a common mistake in assuming that batteries need to be 12,000 to 13,000 Wh/kg in order to be equivalent to gasoline. (Auto companies frequently make this mistake as well in presentations, so don't feel too bad.) This is correct for an abstract energy density held in isolation, but not correct for real cars.

First of all, an electric motor is about 4 times as energy efficient as a gasoline engine at consuming its native energy, so the energy density of a battery only needs to be about 3,000 Wh/kg to be competitive on a consumptive basis.

Second, the 30 kg or so of mass sloshing around in the gasoline tank of a small car needs another several hundred kg of mass in the form of an engine, transmission, exhaust, larger cooling system, et cetera, in order to function, much more mass than the 70 kg or so of electric motor and electronics that a similar size EV requires. These two additional masses contribute to lower energy densities for both gasoline and battery.

This results in a need for only about a 340 Wh/kg battery to match the 12,200 Wh/kg of gasoline.

Similar adjustments need to be made to determine the effective volumetric energy densities, but the result is about the same.

This is why a Leaf say, can get about 100 miles range with a 100 Wh/kg battery, and yet a 30 mpg gasoline car needs 12,200 Wh/kg gasoline, 122 times more, to travel only 3 or 4 times as far!

Isn't physics fun?

· · 7 years ago

@Verify EV (not verified), :-)
"'regman' makes a common mistake in assuming that batteries need to be 12,000 to 13,000 Wh/kg in order to be equivalent to gasoline."

Regman didn't make a mistake. From the article, "In 1925, Sakichi reportedly set out a (yet-to-be-claimed) prize of 1 million yen for the invention of a storage battery that would produce more energy than gasoline." You don't get the prize just by making an efficient powertrain connected to a battery.

· · 7 years ago

Lithium when oxidized actually has about the same energy density as gasoline. But ofcourse, we want to not burn off lithium but use it in a controlled - reusable - manner.

Ofcourse, Lithium Air battery gets energy out by oxidizing Lithium - 11kWh/kg is the theoterical maximum. In practice someone might get to 1kWh/kg - that would be 5 to 10 times better than current batteries. So we could get a lighter (much) Leaf go 250 miles on a charge - say in 10 years.

· EV Driver (not verified) · 7 years ago

My own Electric Vehicle uses at the low end 67 - 100 Wh/Km, and at the high end 277-285 Wh/Km, with a highway nominal of 140 Wh/Km at 100 Kph / 62 Mph >

That is a car, originally getting about 55-60 mpg on gas, a 1989 Pontiac firefly (Geo Metro) that was converted to run on Electricity, some 15 years ago, by High School Students, and - that is with Flooded Lead Acid Batteries, which pack weighs in at 400 lbs.

When I finish my next plan, to build a Lithium Iron Phosphate pack to go where the gas tank was, it will weight about 200 lbs, and while at just some 8 kWh, will have double the range of the 2X heavier Lead Acid Pack, handle cold weather better, charge faster, and be safer since it is a sealed pack with sealed cells, centered in the car, instead of the current positions of batteries in the front and rear crumple zones!

While Current and near forseable Lithium Cells and Batteries might not have the 33,500 Watt hours of energy that a gallong of Gasoline has, the Electric Drive train delivers more than 3X the efficiency of the Internal Combustion Engine (ICE) system, so - when someone actually makes a batter that can deliver more than 33.5 kWh per Gallon of volume, such vehicles it is installed in will go at least 3X as far for the same volume!

Definitely exciting! Or - for a 150 mile range pack, imaging a shoe box (OK - maybe a Boot Box) sized Battery Pack getting the job done!

· Verily EV (not verified) · 7 years ago


I guess I wasn't clear.

I was talking about how to determine what energy density of a battery is needed to make a practical EV that is equivalent in range and weight to a conventional car, and I was showing that it is far, far less than the more abstract question of which fuel has higher energy density.

Without a load for the fuel, there is no motion and no vehicle. The gasoline can only soak into the ground or perhaps make a fire, and the battery can only gather dust.

Equipment is needed to produce rotational energy, and that equipment has mass which needs to added to the mass of the fuel or the battery, and only at this point can that mass be divided into the energy content of the fuel to determine its density.

Likewise, the energy efficiency is very important in determining how much energy needs to be stored -- the energy content of the fuel or battery -- before that division occurs.

You need both in order to determine the actual energy density of battery required. Determining the required volumetric density is similar, except you need to consider the additional volume of the equipment. Remove the equipment and you have no car.

Thus, a Sakichi battery in an EV that is the mass of a Leaf battery will give about 12,200 miles of range, which is hardly equivalent to a gasoline car.

You don't need a Sakichi battery. Worrying about finding one is a waste of time!


· · 7 years ago

I agree. While better batteries are great, and will come, we really don't need them to be much better than today's best. We can build a 300 mile EV right now, it just costs too much. There is really no "need" for more than a 300 mile range. Some of the ICE's I've owned don't have that range, but it's not a concern because there are "charge points" called gas stations. Since most EV's will fill up at home a much smaller number of charge points will handle the occasional need for increased range.
Where increased energy density will help is by giving us more range in a smaller lighter package, which means fewer materials, which should translate into lower costs, if those materials are not too exotic.

· Anonymous (not verified) · 7 years ago

I think the advent of driverless cars will make the limited battery range a non issue. If your vehicle can take itself off to recharge when you get to your destination 100 miles is more than enough.

· · 7 years ago

That makes no sense. It takes less than 10 seconds to plug your car in yourself, who needs the complexity and expense of a car that has to drive somewhere else to plug in?

· Doug Whitehead (not verified) · 7 years ago

I'm a big fan of EV, but talking about driverless cars as a solution to anything is just crazy. There is no need to hitch your hopes on another tech that may be many years to gain acceptance.

· Priusmaniac (not verified) · 7 years ago

Chemical batteries are based on the chemical energy released when an element changes its oxidation state. This is a clear fixed amount of energy than can be equaled at the very best.
On the other hand a capacitor is storing energy in the form of electric charges accumulated on conductors separated by an insulator. The energy content is proportional to the square of the applied voltage and inverse proportional to the square of the distance between the charge carrying electrodes. In other words, the energy content is proportional to the power four of the insulation capacity in V/m of the material between the electrodes. A power four is an enormous effect. It means that likewise superconductors brought a revolution in physics, superinsulators can bring a revolution as well. Of course this is a shift away from the current capacitors development where the focus is on dielectric substances improvement and increased surface area of the electrodes, but I am pretty sure that the next revolution will come from an improvement in old fashion insulator based capacitors equipped with outstanding super insulation materials.

· · 7 years ago

I'm not so sure. Batteries have a big advantage in specific energy density and are not near theoretical limits. I'd count on them continuing to improve significantly before a breakthrough technology in caps.

· EV Driver (not verified) · 7 years ago

Where I like in using Capacitors, or Super Capacitors, in an EV, are for very short drives, easing the high current loads on a battery energy storage system for periods of High Acceleration (Freeway Entry, etc.), and for cars with Regen - (Almost all, if not all, OEM EV's, and more and more personal EV Conversions using AC Motors), the ability to get incredible amounts of energy captured rapidly for fast breaking, and for decending down hills for holding vehicle speed down!

I don't have the number handy - but if you calculate a power need in watt-seconds, you can easily calculate the Super Cap requirements for the figured energy needs from this.
Example - my very short drive to work: if I used the 285 Wh/km figure, then - that equals 60 sconds x 60 minutes x 285 = 1,026,000 Watt Seconds of usable energy storage needed, x a factor of 2-3 for the fact that totally discharging a Capacitor to Zero Volts, to capture all the energy needed and avaiable from them, means you are now trying to drive on (Near) Zero Volts - Not too practical! So - that then means about 3 million watt seconds of energy storage = 3 million Joules of energy storage.

Using - F = C^2/J; where C is coulombs and J is Joules, to determine 'F' (Farads) it can be figured out how many watt-seconds or joules are needed at what volts.(And - No I have not done this calculation, but I know of buses using SuperCaps, so with some digging - I believe I could make it work, too!)

Anyway - a better use of Super Caps is still for floating a high power load off the batteries to the super caps, storing a buffer for acceleration. Just a thought!

· · 7 years ago

The batteries can already handle full acceleration and braking needs. Instead of the expense, weight, and volume of caps you'd be better off just using more batteries.

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