October 28, 2009
Zinc Air Batteries To Beat Lithium Ion?

Kevin Bullis has the details in Technology Review. A Swiss company claims to be making strides toward a longer lasting zinc air battery.

A Swiss company says it has developed rechargeable zinc-air batteries that can store three times the energy of lithium ion batteries, by volume, while costing only half as much. ReVolt, of Staefa, Switzerland, plans to sell small "button cell" batteries for hearing aids starting next year and to incorporate its technology into ever larger batteries, introducing cell-phone and electric bicycle batteries in the next few years. It is also starting to develop large-format batteries for electric vehicles.

Read the full article for the details. Note that the company isn't ready to start selling tomorrow. Whether they achieve what they claim remains to be seen.

During the 2010s will battery technology advance far enough to make electric cars capable of serving most personal transportation needs? If so we would breathe cleaner air and pay less for fuel.

Share |      Randall Parker, 2009 October 28 12:32 AM  Energy Batteries

Paul said at October 28, 2009 5:26 AM:

There is also a company out of MIT working on zinc-air batteries, although I see very little about them on the net.


Rob said at October 28, 2009 9:27 AM:

> If so we would breathe cleaner air

Kind of depends on where your electricity for recharging comes from, doesn't it? If you're burning coal to recharge that vehicle, then you may be worse off than if you burned gasoline. Not only do you have to worry about transmission losses (several percent), but also recharging losses (double-digit percent, if I recall correctly) as well.

Also, I have no idea what widespread use of electric cars would do to the grid. Certainly, if a good percentage of vehicles were electric and their owners drove them home and plugged them in at 6PM on a hot summer day, we would take down the grid. At peak load times, the grid in most places is within a few percent of capacity. Plugging in a bunch of thousand-watt rechargers at peak times would be devastating.

I like the idea of electric vehicles, especially NEVs, but they're going to have to be phased in no faster than we upgrade the grid to accommodate them.

brian said at October 28, 2009 11:20 AM:

Batteries at half the cost, and three times the capacity per volume are game changers for cost-performance if other factors remain the same. Batteries that require air to dissipate their energy would also be safer. Most Lithium chemistries burn so hot and fast you could argue that they're little more than a bomb waiting for an appropriate shunt. Mitigating that risk is a challenge.

Engineer-Poet said at October 28, 2009 12:30 PM:

We don't have to upgrade the grid for quite a while, just use smart chargers.  The grid load falls off steeply by 11 PM and hits a minimum in the wee hours.  Having a smart charger which follows the curve of available generating capacity (and talks to the utility to say how many kWh it needs and by when, and maybe gets a minute-by-minute charging schedule back) wouldn't take much more than addition of a cell-phone chipset with text capability.

Yes, some people will want a full charge as soon as they get home at 6 PM.  I suggest we use V2G so that the people who don't care as long as the car's done by the next morning can sell some juice at 6 PM.  Let them sell at 28¢/kWh, the impatient can buy at 30¢/kWh, and the utility can take 2¢ as their brokerage fee.  The folks who aren't hurrying can refill their batteries at 10¢ or less.

FWIW, a large EV fleet would raise the floor of the demand curve and change the optimal mix of generation toward more base-load capacity.  This especially favors nuclear, which has a fuel cost close to zero.  That would clean everything up.

Nick G said at October 28, 2009 2:07 PM:

E-P, I agree. A couple of quibbles:

Smart charging with 2-way communication is a great idea, but one-way would also work: just send price signals to the EV, and it can decide when to charge based on the price points that have been entered (probably most people would stay with factory defaults).

A large EV fleet would also favor wind, which has zero fuel cost, is slightly stronger at night on average, and has intermittency that needs buffering.

Greg said at October 28, 2009 5:26 PM:

Half the cost and triple capacity is not enough: Arotech has these Zinc-Air batteries available for many years now, but they aren't rechargeable; they are re-processable on-site. The company has the city bus capable of running around 150 mi with air conditioning on one set of batteries, and all infrastructure to reprocess the batteries at the garage - but not a single commercial installation so far.

Wolf-Dog said at October 28, 2009 7:50 PM:


The business model of Better Place will make battery swapping stations available for cars. Separating the battery from the electric vehicle itself, is a major innovation. Israel and Denmark will have eliminated most of their gas stations by 2020. Already Renault-Nissan agreed to build 100,000 electric cars (with swappable batteries) to be delivered to Israel within a few years.

This business model is especially suitable for servicing buses (not just cars) since it is much easier to build battery swapping stations for buses.

Here is a video of how the electric cars of this business model get charged at every street, and also how their empty batteries get swapped with full batteries (by robots at gas stations):


And there are more videos of Better Place here:


In any case, it is astounding that so much progress is already made with so little government money. What we need is a Bronx project for energy research, with $100 billion per year for batteries and electric cars, solar and algae fuels, etc. $100 billion per year is a small fraction of the defence money we are burning for nothing.

Engineer-Poet said at October 28, 2009 7:55 PM:

Price signals aren't enough unless you have an auction, which requires 2-way communication.  If the utility just sends price info, what happens when everybody has their charger set to switch on when the price falls to 8¢ or less?  A 200 MW demand spike over a few seconds with a 0.1¢/kWh change in price would be a problem, to say the least.

I suspect that it might be possible to create a stable system if the chargers sensed grid frequency and controlled power demand according to the phase advancing or retreating; that is a two-way interaction, even if not an explicit one.  It's suboptimal from the POV of the grid manager because there is no way to read total energy required and gear up the generation mix to supply it at minimum cost, but it would avoid the problems like everything kicking on at once and the local substation tripping off.

Nick G said at October 28, 2009 8:40 PM:


It just so happens that I've thought about the demand spike problem, and have several solutions. First, program a very small random variation into the price response: PHEV #1 responds at $.03001, PHEV #2 at .03002, and so on.

Or, have the utility have the ability to code the price signals for individual smartmeters or groups of meters. If you need more demand, send a lower price to a wider pool of meters. If you're concerned about fairness, rotate or randomly vary the selection.

Finally, I agree that it's suboptimal. Better for the utility to know all of the potential demand out there. OTOH, utilities certainly don't know that now, and DSM could be made to work without it.

Fat Man said at October 28, 2009 9:26 PM:

From reading the linked articles, I gather that the zinc in these "batteries" (really more like fuel cells) is in a liquid either dissolved or suspended. If this is true, the question in my mind is why recharge? Recharging takes time generates heat and requires equipment. Why not go to a "filling station" pump out the ZnO and fill it with a new batch of Zn.

Engineer-Poet said at October 29, 2009 4:03 PM:

Fat Man:  You are not the first to have this idea; Power Air Corp is trying to build a company on it.

Suppose that you had a car with e.g. Firefly Energy lead-acid batteries for local travel, and you could plug in a trailer with ZAFCs on it (with or without added cargo capacity) for long trips.  Larger vehicles like pickups could sling the ZAFCs below the bed (and perhaps rent them only when needed); that would permit towing as well.  Would that be objectionable?

Nick G said at October 29, 2009 5:08 PM:


It would certainly work, but I think an ErEV like the Volt is more practical. With only a 40 mile range, the average driver would only drive on liquid fuel for 20% of miles traveled - given that a Volt's fuel efficiency is likely to be 2x that of the average US vehicle, that means a 90% reduction in fuel consumption. That's good enough.

Eventually the internal generator will get very small and efficient, and the liquid fuel will really become unimportant.

I'm curious about this: "Researchers at Michigan State University (East Lansing, MI) will complete its prototype development of a new gas-fueled electricity generator, five times more efficient than traditional auto engines in electricity production, 20% lighter, and 30% cheaper to manufacture. This novel ultrahigh efficiency engine could replace current backup generator technology of hybrid and pPlug-in hHybrid eElectric vehicles."


Nick G said at October 29, 2009 5:11 PM:

Eventually, of course, ErEV/PHEVs will be replaced by something better, but who knows what that will be. I suspect ErEV/PHEVs will be with us for quite a while, given that they need very, very little new infrastructure, and are extremely convenient.

Engineer-Poet said at October 30, 2009 6:23 AM:

I'm very skeptical about that wave thing.  "Five times more efficient" is greater than the theoretical maximum efficiency of a combustion engine; some years ago, vehicles were already hitting ~15% and the limit is less than 60% (set by entropy increase during combustion, among other things).

The PHEV is pretty good, but the economics depend on the price of liquid fuel vs. electricity.  If petroleum keeps heading upward while electricity remains relatively stable, the battery trailer eventually becomes more attractive than the sustainer engine.  The complexity and cost of the car takes a steep drop, too (no emissions equipment or certification).  That is the kind of disruptive change that causes tipping points in markets.

Nick G said at October 30, 2009 4:11 PM:

Yes, 5x looks like hyperbole. Still, if they can go from 15% to 45%....! I'm hoping to hear more detail about this.

Yes, very high oil prices might make a difference. OTOH, I think that oil is unlikely to stay above $120 in a sustained fashion, due to substitution/demand destruction and economic slowdown for oil importers.

Engineer-Poet said at October 30, 2009 4:39 PM:

That tipping point will still be there, though.  If the EV is substantially cheaper, as the economy sinks it will be more affordable to purchase (and the absence of price spikes for its "fuel" makes it much less risky to lend money to purchasers).

We need to start a a ratchet moving things away from petroleum.  The 70's oil price shocks essentially replaced US oil-fired electric generation with nuclear, but that's where it stopped.  Rail transport is perhaps the easiest step, road transport a tougher one, air travel very difficult (it may be cheaper to run bullet trains than to build out a fuel infrastructure to run airliners on something other than oil).

Nick G said at October 30, 2009 6:54 PM:

I have a hard time seeing how the EV could be substantially cheaper than a PHEV. An ErEV like the Volt has a much smaller electric range than a typical EV. That saves more than the cost of a $2k ICE generator (GM's cost), plus the cost of 50 gallons of fuel per year that the average driver would use.

Plus, the PHEV has a 400 mile range, and can be refueled quickly, conveniently and almost anywhere.

I don't really think road transport is difficult in principle - the real hurdle was institutional/social: getting the car industry to commit to something that will make many people's careers and investments obsolete. Now, it's just building out/ramping up to get economies of scale. If it's done slowly it won't cost significantly more than ICE vehicles. If we need to make existing vehicles obsolete more quickly than normal turnover..well, that's a real expense, though not overwhelming.

Regarding air travel:

1) air transport is only about 5M B/day

2) oil production can maintain a level of 10M B/day for 100 years or more

3) kerosene (jet fuel) could be replaced by existing tech over time, even though it would be annoying and expensive - existing tech includes hydrogen, or synthetic fuel - fuel can be synthesized from electricity and atmospheric CO2 even now - it's expensive ( roughly $10/gallon), but doable

4) in 100 years we're likely to have new energy storage tech

5) even if we don't, the combination of higher efficiency air travel, synthetic fuel and high efficiency PV would work pretty well, albeit at a cost per seat-mile that might be, say, twice what it is now.

It's awfully likely that we'll have 50% efficient PV - could it be towed behind, and placed on wings with extra surface area?

non-stop around-the-world solar plane

Prop planes were twice as efficient as jets, when jets took over. Wouldn't prop planes with modern engineering be twice as efficient as current jets? If fuel can be synthesized for $10/gallon, then aviation's cost per mile would be at the same level as it would be now at $5/gallon. I'm pretty sure aviation would do ok with that - please note that the airline industry has always lost money - I don't know why anyone gets into it. Vanity, I think.

Engineer-Poet said at October 31, 2009 10:11 AM:

You're thinking of the cost of high-tech batteries.  Forget those for a minute and look at the balance of the vehicle.  The EV has no engine, no fuel system, and no emissions system; both the ICEV and PHEV must have those.  The EV's motor is both more powerful and simpler than the ICE.  It needs no certification for emissions, which is another big savings.

Now let's look at batteries again.  We have a heap of technologies to choose from, including at least 3 using lead-acid.  If the EV is designed on the Better Place model, its battery can be swapped out in minutes; this means that it could be designed to use any battery with the proper form factor and meeting the interconnection standard.  You could use a cheap lead-acid battery for tooling around town (40 miles range, $60/kWh), and swap for a lithium-ion unit when you need to hit the highway (200 miles, $300/kWh).  If the car needs 250 Wh/mi the lead-acid battery costs $600 (one per vehicle, much cheaper than an engine) and the lithium-ion could cost $15,000 (perhaps 1 battery per 10 vehicles).  Your total capex for batteries, both the lead-acid dedicated to you and the share of the li-ion for long trips, is $2100.  This is on the order of the cost of an ICE drivetrain.

You're right about the relative quantities of oil production and air travel's consumption, but you're missing one thing:  other demand.  As oil production slides, the marginal barrel will not be priced at the cost of the marginal barrel of production but at the cost of destroying the marginal barrel of consumption.  This price will sag in economic contractions (when demand for air travel will sag too) and spike when the economy tries to expand (pricing air travel out of many people's reach).  Oil, and anything with a price which follows oil (such as liquefied natural gas) is going to cost too much for mass air travel.  We are heading back to a situation of air travel only for the elites, the "jet set".

Yes, props are more efficient than jets (though fanjets slash the difference).  However, a contracting air sector won't have the capital to invest in a new generation of liners.  It will be cheaper to spend money for oil to run the old planes.  There are a lot of them, and they are either paid for or will be bought for a song in bankruptcy; the owners won't go broke from debt payments during the sags.

Randall Parker said at October 31, 2009 11:36 AM:


You make a lot of sense here. I hadn't considered this possibility:

You could use a cheap lead-acid battery for tooling around town (40 miles range, $60/kWh), and swap for a lithium-ion unit when you need to hit the highway (200 miles, $300/kWh).

Why pay to own the really expensive battery when you rarely need to use it? You could even own the cheap short range battery and just rent the high range battery for a trip. Interesting idea.

I can also imagine another way to do this: Own a car with a short range battery and rent a car which has long range. If you have a family going on a vacation you have different needs for the vacation trip (e.g. luggage space, more seats) than for the work commute.

I can easily imagine 2 seater EVs with no luggage compartment for commuting. Few cars have more than 1 person in them for commutes.

What I want to know: When is a lighter lead acid battery going to hit the market?

Randall Parker said at October 31, 2009 11:53 AM:

E-P, I wonder if there's a difference between these two prices:

As oil production slides, the marginal barrel will not be priced at the cost of the marginal barrel of production but at the cost of destroying the marginal barrel of consumption.

Won't the market make them equal over time?

What I also really wonder: If you could draw a graph of the cost of destroying a marginal barrel of consumption over the next 10 years what would it look like? Where would it peak? In the middle? At the end? On the one hand we will have more and more tech for substitutes. On the other hand, the remaining use cases will have the hardest problems with substitutes. Airplanes require a new liquid fuel. So they seem the hardest case to substitute for.

To put it a perhaps more useful way: For each current use of oil what's the cost of destroying a marginal barrel of demand? That cost of demand destruction for each use will vary by marginal barrel and thru time. The initial barrels will cost less to stop using. The subsequent barrels will cost more to stop using unless technological advances lower the cost of demand destruction.

Engineer-Poet said at October 31, 2009 2:14 PM:

Firefly Energy has the Oasis batteries going into service.

Won't the market make them equal over time?
I don't think so.  The cost of the marginal barrel of production has to be low enough that the oil firm can stay in business during the lulls, while the marginal barrel of consumption is priced at whatever the market will bear.  The difference will be increased by tight credit.

The cost of destroying the marginal barrel of consumption is at least partly psychological.  If the idiots whose inadequate dick size makes them compensate with Hummers and the like were hit over the head enough (another $3/gallon in taxes would probably do it), a substantial amount of consumption could be destroyed at negative cost.  Electric generation on islands and other remote areas may cost money to substitute, but some have resources like wind which are easily tapped.  Some of those are being substituted already, even in the credit crunch (Dexia negotiated a deal recently to do just that).

I still think the best fuel for airliners is something like LNG, because it would make such a great coolant for the engine hot sections and lends itself to regenerative cycles.  The fuel load would not only be lighter (albeit bulkier), the engine efficiency could be increased.  But I don't know if the capital is there to create a new generation of LNG engines, retrofit airliners, and add the fueling infrastructure.  Too long a time frame, high-risk.

Randall Parker said at October 31, 2009 4:36 PM:

E-P, I clicked thru on a Firefly press release and they claim their batteries are one fifth the cost of NiMH and Li ion batteries. I wonder if that's lifecycle cost or initial cost. Sounds like lifecycle costs since they are claiming similar longevity versus their more expensive competitors.

If Firefly can really pull of what they are claiming then that's a game changer. Use lead acid batteries around town and even for most commutes. Just use the expensive batteries for longer trips.

Nick G said at October 31, 2009 5:32 PM:


I think that what you're describing is certainly feasible as an emergency solution. It's certainly valuable to know that, as a boundary, our problems have such a simple, low-cost solution. Combine a low-cost LA NEV with zipcar.com or a similar car-sharing service, and you've got a great solution.

OTOH, I don't think it's a solution that we're likely to see as a dominant EV-type solution. I don't really think most people want something like a NEV. Consider: the first Honda Insight was an elegant solution: reasonably priced, with MPG around 60. What's not to like? Well, it was a small 2-seater, and it never sold.

Further, it would require very careful driving. The EV-1 had a 16.5KWH LA battery, with a theoretical range of 135 miles( http://avt.inel.gov/pdf/fsev/eva/genmot.pdf ), but drivers found the practical range was much closer to 60 miles, and range anxiety was a big issue. I've had people tell me that the range of LA with normal driving is much smaller than the theoretical range, because of Peukert's law: a low rate of discharge is needed to get the rated KWHs. "The Peukert law becomes a key issue in a battery electric vehicle where batteries rated at 20 hour (or even 100 hour) discharges are used at much greater rates of about 1 hour." http://en.wikipedia.org/wiki/Peukert%27s_law

Most of the price premium for the Volt is due to new parts at low volumes, a problem it shares with other EVs, which aren't cheap. The li-ion cells are only $350/KWH even now, and the manufacturer (LG) expects costs to fall by 2-4x in the next 5 years. That will put it in the range of Firefly, which I think is roughly $200 at the moment.


It's very hard to predict the price of oil over any short-term time-frame, but alternatives exist for freight, personal transportation, home heating and electrical generation at well below $100/bbl - these represent roughly 80% of oil consumption. This suggests that in the long-term, oil won't stay above $100. Furthermore, consumers and industry are sensitive to oil prices - even Chinese demand fell in 2008, and China has eliminated fuel price caps & subsidies.

Finally, personal transportation in the US has substitutes that are cheap and fast: car pooling, telecommuting, tele-presence, bikes, etc.

Engineer-Poet said at October 31, 2009 10:07 PM:

Nick, a Better Place EV is not an NEV.  My proposal for cheap batteries for every day would be like driving around with only $3 of gasoline in the tank (which some people do); if you want to go someplace far away, you go to the station and fill it all the way up (get the high-tech battery).  Otherwise, same car.

It's my understanding that Firefly batteries have much lower internal resistance due to shorter diffusion distances and would not see such large issues with Peukert's Law at normal discharge rates (they can also be charged much faster, which helps with things like regenerative braking).  Also, if Firefly is $200 at the moment, and OTS flooded lead-acid is $60 (with 3x the lead per kWh), Firefly has at least as much room to cut cost as Li-ion.

Nick G said at November 1, 2009 9:01 AM:


I like Firefly batteries too. I'm baffled that they haven't taken off more quickly. At this point, their only near-commercial sale is to a mass-transit agency in their home-town of Peoria, which has a vested interest in supporting it. They've laid off 1/3 of their staff, and are limping along with DOD support (the DOD likes it for run-quiet applications).

I understand why GM didn't use it: it wasn't quite developed enough at the point GM needed to finalize their design & testing program, and it didn't meet CARB requirements (10 years, 150K miles). But why aren't truckers buying it for "hotel" power needs?

Engineer-Poet said at November 1, 2009 7:31 PM:

They are.  Look at their news releases.

Nick G said at November 2, 2009 9:53 AM:

This is the latest truck-sales related press-release I can find on their web-site: OASIS_PROTOTYPES_HIT_THE_ROAD.pdf

Much as I'd like to, I see no sign of real commercial sales.

Nick G said at November 2, 2009 9:56 AM:

Their early arrangement with Husqvarna also appears to have fallen through.

The fact that the DOD is hanging in there suggests that their tech is truly promising, but having real problems of some sort - perhaps in manufacturing scale-up.

Engineer-Poet said at November 4, 2009 7:03 AM:

That's the sort of place where money helps.  I opined back in the early 90's that the PHEV was the most promising technology in the near term, but the California ZEV mandate failed to create any incentives to build them or improve the components.  Battery technology for vehicles went nowhere.  In retrospect, this is no surprise; some very low-volume EV models offer no prospects of the sales which would justify major industrial process investments.

I'm not sure what we could do to fix this.  I suppose that a standard for cell size, etc. could help, but the question is what market could take them while waiting for vehicle manufacturers to get geared up to take them.  The obvious answer to me is utility load-levelling (which can take used packs with partial capacity after they're run down too far for regular vehicular use).

Nick G said at November 4, 2009 11:33 AM:

Yes, utility load-leveling would be a good application. Also, CARB could relax it's 10 year/100K mile requirement.

Hopefully the DOD will hang in there, and get Firefly to economies of scale. Then they can sell to the demanding corner of the LA market, like trucking & winter-proof LA's, like Husqvarna; and then move up to PHEV/EVs.

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