High-efficiency zinc-air battery developed

May 29, 2013
This is a rechargeable zinc-oxide battery in a tri-electrode configuration with cobalt-oxide/carbon nanotube and iron-nickel/layered double hydroxide catalysts for charge and discharge, respectively. Credit: Yanguang Li, Stanford University

Stanford University scientists have developed an advanced zinc-air battery with higher catalytic activity and durability than similar batteries made with costly platinum and iridium catalysts. The results, published in the May 7 online edition of the journal Nature Communications, could lead to the development of a low-cost alternative to conventional lithium-ion batteries widely used today.

"There have been increasing demands for high-performance, inexpensive and safe batteries for portable electronics, electric vehicles and other energy ," said Hongjie Dai, a professor chemistry at Stanford and lead author of the study. "Metal-air batteries offer a possible low-cost solution."

According to Dai, most attention has focused on lithium-ion batteries, despite their limited (energy stored per unit volume), high cost and safety problems. "With ample supply of oxygen from the atmosphere, metal-air batteries have drastically higher theoretical energy density than either traditional aqueous batteries or lithium-ion batteries," he said. "Among them, zinc-air is technically and economically the most viable option."

Zinc-air batteries combine and zinc metal in a liquid alkaline electrolyte to generate electricity with a byproduct of . When the process is reversed during recharging, oxygen and zinc metal are regenerated.

"Zinc-air batteries are attractive because of the abundance and low cost of zinc metal, as well as the non-flammable nature of aqueous electrolytes, which make the batteries inherently safe to operate," Dai said. "Primary (non-rechargeable) zinc-air batteries have been commercialized for medical and telecommunication applications with limited . However, it remains a grand challenge to develop electrically , with the stumbling blocks being the lack of efficient and robust air catalysts, as well as the limited cycle life of the zinc electrodes."

Active and durable electrocatalysts on the air electrode are required to catalyze the oxygen-reduction reaction during discharge and the oxygen-evolution reaction during recharge. In zinc-air batteries, both catalytic reactions are sluggish, Dai said.

Recently, his group has developed a number of high-performance electrocatalysts made with non-precious metal oxide or nanocrystals hybridized with carbon nanotubes. These catalysts produced higher catalytic activity and durability in alkaline electrolytes than catalysts made with platinum and other precious metals.

"We found that similar catalysts greatly boosted the performance of zinc-air batteries," Dai said. both primary and rechargeable. "A combination of a cobalt-oxide hybrid air catalyst for oxygen reduction and a nickel-iron hydroxide hybrid air catalyst for oxygen evolution resulted in a record high-energy efficiency for a zinc-air , with a high specific energy density more than twice that of lithium-ion technology."

The novel battery also demonstrated good reversibility and stability over long charge and discharge cycles over several weeks. "This work could be an important step toward developing practical rechargeable zinc-air batteries, even though other challenges relating to the zinc electrode and electrolyte remain to be solved," Dai added.

Explore further: Research proves there is power in numbers to reduce electricity bills

More information: "Advanced zinc-air batteries based on high-performance hybrid electrocatalysts," www.nature.com/ncomms/journal/… full/ncomms2812.html

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User comments : 11

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Eikka
3.3 / 5 (10) May 29, 2013
The metals involved also form a nifty acronym: CoNiFe(r)
EyeNStein
2.4 / 5 (8) May 29, 2013
An actual numerical energy density figure would be good. "Twice lithium-ion" gives them too much room to massage the figures just to impress investors! There is a huge spectrum of figures for Li-ion from old safe technologies to modern high performance technologies.
No prizes for guessing which they would choose to compare themselves to!
semmsterr
3 / 5 (4) May 29, 2013
I like how this new technology sounds but something just occurred to me: When this goes into mass production, will it have an effect on the atmosphere? Given that we're removing our oxygen generators, ie. forests, at an ever accelerating rate?
Feldagast
3.7 / 5 (3) May 29, 2013
When does it go on sale? If you read it uses O2 when discharging then while recharging releases O2, so its neutral on oxygen use.
antialias_physorg
3.5 / 5 (8) May 29, 2013
When this goes into mass production, will it have an effect on the atmosphere?

No, since when you recharge it the oxygen is released back into the atmosphere. It's a battery - not a primary fuel source.

(BTW trees aren't an oxygen source - they are oxygen neutral over their entire lifecycle. You only get net oxygen if part of the tree is buried and doesn't rot - i.e. if you turn it into coal or oil)
RealScience
5 / 5 (5) May 29, 2013
@semmsterr - There would not be a significant impact.

First, the batteries release the oxygen when they are recharged, so it is only the energy from a single discharge cycle that pulls oxygen from the air. And second, even if we end up with a lot of discharged batteries around, it would not make a significant difference in the amount of oxygen in the atmosphere.

For comparison, decades of the world's entire fossil fuel use has added only ~100 ppm to the CO2 in the atmosphere. This makes a difference to CO2 levels because those are only a few hundred parts per million (ppm) or the air.

But oxygen is ~22% or 220,000 ppm or the air, so even if we ran the entire world on the zinc batteries and never recharged any of them, it would take hundreds of years to use up even 1% of the air's oxygen (and we'd run out zinc before then).
Shakescene21
4.2 / 5 (5) May 29, 2013
"...rechargeable zinc-oxide battery in a tri-electrode configuration with cobalt-oxide/carbon nanotube and iron-nickel/layered double hydroxide catalysts for charge and discharge, respectively"

Wow! Now this is a high-tech battery! I can't wait until I have one of these in my electric car, and I can brag about it to my gearhead friends.
Howhot
1 / 5 (2) May 29, 2013
Brilliant! This is a fantastic design. I hope to see it developed into a competitively priced auto 12V lead/acid replacement battery within 2 years. As the Shakeman said; "Wow! Now this is a high-tech battery! I can't wait until I have one of these in my electric car"

Me too!
Shakescene21
1 / 5 (1) May 30, 2013
@Howhot -- You have a good idea about replacing the 12V lead-acid battery. I doubt if this would be price-competitive with with lead acid for relatively small capacity, say 700 cca. However, auto electrics are becoming more extensive and lead batteries quickly become too heavy as your needs increase.
Also, sometimes the consumer will pay a hefty premium for a smaller and lighter battery. The battery compartment of my VW bus is in an awkward location, and as I get older I worry about wrecking my back trying to get batteries in and out of that corner. I would gladly pay an extra $100 for a smaller and lighter battery that wouldn't strain my back so much.
dakiro
not rated yet Jun 03, 2013
I wish this becomes a reliable end product, still waiting for a good range electric car, one which does not cost a fortune.
antialias_physorg
1 / 5 (1) Jun 03, 2013
Brilliant! This is a fantastic design. I hope to see it developed into a competitively priced auto 12V lead/acid replacement battery within 2 years.

Probably going to take a bit longer than that, since 'competitively priced' always includes setting up supplier networks, factories, standardizing design, ... any one of which easily will pop that 2-year mark in my experience (though I do hope I'm wrong on that score this time)

Been following the development of zinc air batteries for quite some time and this is the breakthrough they'd need.

Recently I've been looking at sodium-air batteries (whose specs look so outrageous in terms of even lower cost/lower toxicity/higher energy content/absurdly high number of recharge cycles that I'm not even sure they're real)