KERS Stumbles on Fast Path to F1 2009 Season
New Zealand Awards NZ$45.6M for Alternative- and Bio-Fuel Research; LanzaTech NZ$12M Low-Carbon Gasoline Project Leads

Report: Toyota Focusing on Metal-Air Cells for Next-Generation Battery Technology

The Nikkei reports that Toyota’s newly established department for battery research (earlier post) is focusing on metal-air cells as the next-generation battery technology for its vehicles.

In June at Toyota Environmental Forum in Tokyo, Toyota President Katsuaki Watanabe said that the company was setting out to develop an innovative next-generation battery that far outperforms lithium-ion batteries.

Watanabe was referring to what’s known as a metal-air battery, according to Toyota Executive Vice-President Masatami Takimoto. In this type of battery, electricity is generated by a reaction between oxygen in the air and a metal like zinc at the negative electrode. The battery does not require the use of a combustible liquid electrolyte, so there is no danger of ignition as is the case with lithium-ion batteries. Moreover, an air battery has over fives times the energy-storage capacity of a similarly-sized lithium-ion battery...It may take some time before air batteries reach the practical stage, but Toyota believes that they will ultimately become the next-generation battery technology of choice.

...Toshiba Battery Co. has conducted research on air batteries for many years and knows their weak spot: they don’t perform well when made in large sizes. Because of this experience the company has no current plans to develop air-batteries for cars. However, the company acknowledges the large latent potential. “If the performance can be improved they could end up finding use in a wide range of applications (including cars),” agreed Teiji Okayama of the technology development department.

Toyota founded a chair for research on advanced batteries at Kyoto University, and will carry out research in collaboration with chair professor Koji Nishio.

A team of researchers led by Dr. Stuart Licht at the University of Massachusetts, Boston, recently published a paper on the development of a vanadium boride (VB2)/air cell that offers an order of magnitude higher energy capacity than lithium-ion batteries. (Earlier post.)



also Al Air is promising


My understanding is that metal / air battery are not rechargeable , their anode need to be recycled to be re-used. therefore I don't see how do they fit to automotive market . I am wrong ?


A regenerated module exchange system would be required. Regeneration Al-Air modules may use mostly electricity. I doubt that the process would be as efficient as recharging an ESSU with lithium batteries or super caps.
However, an AL-Air ESSU could require much less space and have less weight, making it a better unit for personnal transportation vehicles.

Quick plug-in regenerated modules could be exchanged at the corner gas station in 3 to 5 minutes.

Alternatively, many people could eventually have their own module regeneration station, but the cost may be prohibitive unless you have many vehicles.

Another interesting alternative to liquid fuel and ICE.


Service station owners would love this since it would give them a continued reason to exist (in a less toxic form).


I ponder a bit about this pluggable module battery that you could swap at a station that would take care of the recharging. The concept might look nice but there is significant hurdles. Firts keep in mind that an automotive will be something like 600pounds, so you need a solid robot to do the job in a matter of minutes, but why not, 2nd the problem is that the swap might be fast but the recharging will be slow, so means that the staton would need a huge storing of these modules (which would need to be standardized in size and pluggability). The problem is the demand, you might have a hundred of customers in a couple of hours (remember the autonomy is limited, so you go to the station quite often). So for the process to work the station needs a huge buffer of modules because the recharging time is slow and the demand of the customer works by peak. Now think about the automated device that can handle hundreds of battery pack weigthing 600pounds each, quite a piece of furniture indeed.

Not impossible but not very easy to implement, I think the beauty of electric car is that you can recharge them at home, along the road, or on the parking lot, so this battery swaping station idea seems like a flaw in the electric car idea to me.


I think treehugger makes an excellent point.


I think treehugger makes an excellent point.


Treehugger does make an excellent point.
Here's a thought:
Let's say Metal-Air batteries might see use 5 to 10 years out, just as a guess. IMO Li Ion BEVs and E-REVs (Series-PHEVs) will allready be making in-roads in replacing ICEs and HEVs. Look up Volt (sedan), Aptera (2 person commuter), XH-150 (prototype SUV), others?. You will be able to purchase a vehicle that mostly runs on electricity from home. Many families in the USA will opt for newer freeway capable BEV sedans since they already have several vehicles. BEVs will also probably dominate in places like Isreal, Hawaii, Caribbean islands, and other places where you can't drive very far anyway. You'll probably be able to plug-in to recharge at work and some stores while you work or shop.
OK, in a market with these options why purchase a vehicle requiring you to stop at a gas station, or Metal-Air battery station? Maybe the niche for these batteries will be to replace the ICE generator providing the Extended-Range in E-REVs? You'd really only need them swapped during longer distance traveling.
A little bit different picture to consider.
One thing for sure:
Nice to see more options for fossil fuel replacement.


Dr. Stuart Licht proposes a non-rechargeable battery where an anode cassette would be changed at a filling station after 600 miles.
He claims his battery gives a BEV similar or better range than an ICE with the same weight of gasolene.
Toyota has already shown a prototype of the long term replacement for the Prius which is half the weight. Toyota is likely to use a lightweight body for its Prius size BEV.
Thus we can expect a range of 600 miles from 40 to 50 kg of fuel or metal-air battery.
Can anyone say what fraction an anode comprises of the weight of a battery?
If we guess an anode cassette would be 10% of the weight at most, that would suggest 4kg to 5kg of anode cassettes per BEV.
As these cells work best in small sizes, their might be several cells in a single BEV battery, so perhaps 5 or 10 cassettes each weighing 500g to 1kg.

Changing a few cassettes weighing 5kg or less on a purpose designed car in 3 to 5 minutes sounds reasonable. Regenerating racks of anode cassettes sounds like a reasonable business proposition for an existing small local filling station.

The anodes sound very high tech, so the anode cassettes are likely to be expensive. Would an affluent owner be able to store a spare 5kg set at home or in the car for long trips to areas without regeneration facilities?
That would enable the owner to travel > 1000 miles before visiting a regeneration facility.



In the longer run, I agree with you that a multiple cassettes battery pack is a strong possibility.

Exchanging 6 (5 to 10 Kg), (5Kwh to 10 KWh) cassettes could be hand done in about 5 minutes without the use of expensive robots.

For those who can afford it, it would be possible to carry a spare cassette set in the car trunk for safety and to double e-range.

Another advantage would be added scalability. Small cars could use 4 to 6 cassettes while larger cars and small trucks could use 12 to 18 small cassettes or larger size cassettes.

An interesting alternative.


They could work well as range extenders in PHEVs.
You charge it at night, and do most of your day to day driving on the battery.
You only need one engine, not 2 with an ICE PHEV.

If you need to go further, you start to use the metal-air battery. As you won't do this very often, swapping batteries won't be a big problem.

If you are doing huge miles, get a diesel (hybrid).

If you are doing moderate miles, with an occasional long run, a metal/air + Lion battery PHEV would be fine.


if it is only the anode that you have to swap and it weight less than 20Kgs, then the problem might be quite different indeed than swaping a 600pounds of battery.

I am interested to know more about this anode swap only stuff


I wonder what's the efficiency of such a swapping and regenerating system, compared with a methanol-fuel cell. It would do exactly the same (oxidize something to produce electricity), except you just refuel methanol and dump CO2 into the air. The CO2 is recycled and regenerated to methanol with the same energy-source you would use to regenerate the metal-air cell.


Well I looked at how a air/zn battery works and this swaping anode only doesn't sound right, at least without trade off. An Zn / Air cell needs an hermetic cell containing Zn an the electrolyte (KOH) the nergy density of the cell is 200Wh/Kg.The recycling of the cell requires to dissamble the cell and recycle separately the ZnO and The Eletcrolyte, Well I don't see how this anod swap only can works, I am no even sure that the recycling could be done in a station at the corner of the street given the complexity.

Toyota claims the don't use an liquid electrolyt, so it is a gel or a polymer, the Zn is a powder or small pellet to offer large area of reaction, how do you easily separate them ?. One problem of Zn/air battery is that they have a rather high internal resistance so peack power an efficiency of storage are not great despite their high energy density.

Let's see how this stuf works, but sounds fishy

P Schager

Commenters here seem to be unaware of the work of ReVolt Technology ( They claim to have solved the rechargeability problem for zinc-air and to have a product on the way. Since Toyota is pitching this as a competitor to lithium-ions, which are rechargeable, I assume they are also envisioning a rechargeable one.

The article says the batteries don't scale to large-format; note that this issue never stopped Tesla Motors. That's just a manufacturing challenge. The most important thing is that there's no resource limit. There's zinc enough to go around for everybody.

Other characteristics apparently compromised somewhat with zinc-air are cost and lifetime, going by ReVolt's chart. And I believe that charge efficiencies for zinc-air are much lower than what EV proponents have been assuming, the 70-90% typical of mainstream battery types. Nonetheless, a rechargeable metal-air battery would be ideal as a second battery in a BEV, for occasional use and for security-blanket range extension, as Mahonj pointed out. These could make BEV's competitive in a much larger niche.

Toyota has indicated that they are thinking long term on this, probably a couple decades out. Sounds like about how long it will take for ReVolt's patents to run out, after which Toyota might be able to seize the initiative if they invest patiently starting now. ReVolt, for their part, are showing only a minimal interest in targeting EV's, less than they were, possibly knowing that they're being targeted by keiretsu. To me it's one more indication that the patent system needs to be reformed if we want to see reform technology that breaks oil dependence come to life in a timely manner. As it is, high technology business in this former low-tech industry is too much of a destructive, ugly war. Patent owners can too easily get too much veto power over technology advance.

With reform, I'd expect to soon see a rechargeable Vanadium Boride-air battery, or something even more interesting.


In the source article Dt Licht mentions:
"the VB2/air cell has an intrinsic volumetric energy capacity of (1.3 V) × (20.7 kAh L−1) = 27 kWh L−1 (= 97 MJ L−1 = 5.3 kWh kg−1)."
"the practical vanadium boride fuel has a lower limit of 18% of its intrinsic 27 kWh L−1, for an estimated vanadium boride air practical storage capacity of 5 kWh L−1."
"the practical capacity of gasoline (2.7 kWh L−1)"

This implies that the weight of his cell would be:
2.7 / 5 x 5.1 = 2.754 times the weight of a tank of gasoline with the same volume of litres.
So VB2-Air batteries replacing a gas tank would weigh:
40 litre gasoline vs 110kg battery
50 litres gasoline vs 138kg battery
60 litres gasoline vs 165kg battery (about 364 lbs).

If the whole battery needs to be changed to reprocess the anodes, shifting up to 400 lbs in 3 to 5 minutes sounds like a forklift job.

The "Solar thermal processes" to regenerate VB2 sounds like it needs an industrial chemical plant:
"Traditionally, vanadium boride was prepared ... via carbothermal reduction of V2O5 and B2O3 above 1600 °C"
"Liquid (higher temperature, solar driven), rather than solid, Mg, should facilitate the recharge formation of VB2"


This startup reminds me of another startup : Europositron. a few years ago, they were promising a rechargeable aluminum battery that would outperform everything else. where are they now ? I am always skeptical when a startup comes with a technology that goes agaisnt the main stream promising the moon. it rarely happen to be true. But will see.


It's easy to imagine a car with Li-ion for 80 miles range and a metal air range extender for longer trips.

Much less infrastructure is required than for gasoline, as people still re-charge at home 80% of the time.


Interesting point. I don't know if it is feasible to have both Li-ion battery technologies and metal-air cells in the same car.

You are correct. It will be an industrial process.

Beyond all this hoopla, has anyone performed a LCA on these metal-air /VB2-air cells to determine if they are better (energy-, emissions-, power density-wise) than the Li-ion or other rechargeable technologies?

Henry Gibson

Never allow any car to be built that is not a plug in hybrid.

Super-capacitor systems for cars or trucks or busses cannot store as much energy as is in a large flashlight battery, but they can deliver it in a few seconds. They never should be thought of to replace batteries, but only should be used in conjunction with batteries and never alone. Lead batteries with built in super-capacitors have been built. Small, high power, flywheels can and should be used in many cases as a less complicated cheaper substitute.

A set of zinc-air cells could be held in reserve for electric cars like the TH!NK for emergency power to get to an electrical outlet. A cheaper system is a large model airplane engine that burns gasoline to run a simple generator at high speeds for high power at low weight. TZERO used a motorcycle-engine-generator for infinite range at full speed. ..HG..



All cars should have a 20KWh Altairnano (or similar) battery as the base configuration.

1) 200KW of peak power
2) About 80 miles range
3) Long life heavy duty cycle
4) Quick charge capability

Take your pick for range extenders, smelly oil, polymer batteries, fool cell, metal-air. My favorite: Stop for a pee and cofee every 1 1/2 hours.

Disclosure. I have a pittance invested in altair. It can't make me rich.

P Schager


Here are some reasons to go with a hybrid battery pack solution instead of an ICE range extender:
1. No hazardous fuel such as gasoline to carry and pump
2. No need for oil and other fluid and filter changes and all the other high maintenance of an ICE
3. No need to put in a tailpipe, fuel filler, big air system for the radiator, firewall, engine insulation. No need to arrange the car's architectural layout to be limited by the many requirements of the ICE (big cooling air intakes, hot exhaust, crash issues, major heat issues, fire hazard etc.)
4. Can be used indoors and other places you don't want toxic exhaust in people's faces
5. No (or negligible) unwanted noise
6. No nasty grease on your hands after fixing it
7. Much higher reliability feasible
8. Way fewer parts to inventory/retain access to to support it, and fewer skills needed to be its (or your own) mechanic
9. No smog tests and smog issue fights; no clouds over its status as a clean-air vehicle, or complicated incentive regimes and accounting systems that have to be worked out as it's a straight ZEV
10. More thoroughly a cure for (mostly fossil) fluid fuel dependence; can be charged from solar panels or wind including the "range extender's" part
11. Above all, the engineering costs and barriers to entry are dramatically less. This means the upstarts can pose a real challenge to the auto giants and force them to face the issues of things the public is clamoring for but they hate to be bothered with, such as oil independence and the environment. Consumers will get more choice and freedom. (OK, now you know why it hasn't been happening.)

The hybrid pack would be ideal for small city cars. Of course, it won't be for everybody. A biodiesel range extender could take you for several hundred miles easily without the fire hazard or petroleum. But lots of people can give the long trip task to another vehicle. Opening up a niche to make the EV take off so it can mature is the most important thing.

Long term, there are other long-trip solutions that could be developed, such as charge-while-driving lanes, car trains that allow energy transfer on the freeway by pushing or towing, made-easy battery swaps, or really fast charging that would render the ICE passe.


@ P Schanger

Your calculation are not correct. Shall be this way:

So VB2-Air batteries replacing a gas tank would weigh:
40 litre gasoline vs 16,25 kg battery
50 litres gasoline vs 20,25 kg battery
60 litres gasoline vs 24,30 kg battery (about 53,61 lbs).
On other hand I like thermal "recharging" process above 1600 C. It could be more energy efficient than any electrical recharge from primary energy use point of view and give us process efficiently close to 100% when electrical process (including power generation) never exceeds 50%. My problem is that I don't know most of details on Metal-Air battery "recharge" process.

Reality Czech

The metal-air regeneration processes appear to require electricity or a chemical reductant (carbon, magnesium). This must be added to the process energy and GHG figures.


a Zn/air battery used as a range extender on a plug-in hybrid instead of an ICE is a brillant idea, though it would still requires something like 600 pounds of battery to get 300miles of extension. The problem is the infrastructure. But the idea is worth ivestigating

The comments to this entry are closed.