CleanTechnica is the #1 cleantech-focused
website
 in the world. Subscribe today!


Batteries EV

Published on September 9th, 2013 | by Guest Contributor

15

Zinc-air Battery Company Claims Novel Electrolyte Will Do The Trick (CT Exclusive)

Share on Google+Share on RedditShare on StumbleUponTweet about this on TwitterShare on LinkedInShare on FacebookPin on PinterestDigg thisShare on TumblrBuffer this pageEmail this to someone

September 9th, 2013 by
 
Move over, lithium-ion. A start-up company in northwestern Montana reports that it has solved the rechargeable problem that has dogged zinc-air battery development and will soon be in competition with the dominant lithium-ion technology.

Ron Brost, CTO and CEO of ZAF Energy Systems, reports his research team has developed a zinc-air prototype that produces two times the energy of a lithium-ion battery at a third of the cost, with applications ranging from powering cell phones to airplanes.

The technology, which has four (or pending) patents, was developed by an offshoot of four-year-old ViZn Energy Systems (formerly Zinc Air, Incorporated), which is beginning to commercialize its zinc-iron redox grid batteries.

Several other companies and research labs have reported breakthroughs in creating a zinc-air battery in the last few months, including Eos Systems and Fluidic Energy.

Advantages of zinc over lithium-ion are many and obvious: zinc is a readily available and cheap mineral, with resources totaling 1.9 billion tons worldwide; it costs about a third what lithium costs; it weighs about half what lithium weighs in comparable applications; and while lithium-ion batteries have caught fire under certain trials, zinc is environmentally benign, going to zinc oxide (the main component of baby powder) after playing out in a battery. And zinc oxide is easily recyclable; Brost claims the ZAF battery itself will be recyclable.

But let’s look at what ZAF scientists say their prototype can do. Brost wrote in a white paper that research institutes and industrial labs have verified the basic function of rechargeable zinc-air cells, but three basic problems have remained: the air catalyst must be stable and convert oxygen to hydroxide during discharge and evolve oxygen during charges; the zinc electrode must be protected against air oxidation in order to prevent self-discharge and must be able to be formed and reformed hundreds of times without loss of energy or shorting the cell; and the alkaline electrolyte cannot lose water as it is exposed to a continual stream of air, nor can it react with air contaminants such as carbon dioxide.

Brost says the ZAF prototype battery solves these problems.

First, they’ve achieved 400 Wh/kg when, previously, 180 Wh/kg was the norm with zinc-air batteries, which means that the prototype has achieved at least two times the energy output of currently used lithium-ion batteries. They’ve developed a highly efficient bi-directional air cathode and made all three components of the battery bi-directional. And they have developed the first solid-state electrolyte to be used in a battery. Instead of a typical liquid or paste alkaline electrolyte, the ZAF battery uses a solid polymer electrolyte that limits the amount of oxygen that can pass through, while allowing ions to pass freely. This substantially increases the number of recharges and extends the battery life.

Brost notes that problems of dendrites forming in zinc batteries are addressed through proprietary anode and electrolyte designs that both limit dendrite growth and prevent shorting.

Howard Wilkins, chairman emeritus at ViZn and holder of a patent on the ZAF battery, reports that ZAF licensed a fuel cell technology developed at Lawrence-Livermore National Labs. “The technology was a fuel cell that was mechanically rechargeable [it had to be rebuilt to recharge]. We found a way to make it electronically rechargeable. That increased the energy by 300 percent and then we made it rechargeable,” he says.

He says the electrolyte in the ZAF battery has been proven rechargeable at 500 charges and researchers are “trying to get beyond that.” When asked if 500 charges would be sufficient, Wilkins noted that a ZAF battery lasts almost three times as long as today’s batteries, so in a cell phone, for example, a ZAF battery might only need to be charged once a week rather than several times a week.

EVOne of the main applications ZAF is aiming its research toward is the electric car battery. Brost has about 12 years of experience in leading battery teams at Ford Motors and Coda Automotive. He said one of ZAF’s challenges is to “get the cycle life up,” but added that the ZAF battery stores a lot more energy than other batteries. “If we build an electric vehicle with a 500-mile battery, with 500 recharges, that’s 250,000 road miles, so we’re looking at it that way. Five hundred cycles is a reasonable customer expectation,” he says.

Wilkins, a former medical researcher and one of the pioneers of the soft contact lens, says the ZAF technology is in some ways similar to contact lens chemistry. In doing research at Pennsylvania State University and Oak Ridge National Labs, Wilkins says researchers were looking for a material for the contact lens that let oxygen in. Conversely, with the zinc fuel battery, they were looking for a way to make the electrolyte ionically conductive, but oxygen limiting.

Another member of Brost’s team was discovered as a postdoc at Montana State University. Adam Weisenstein had been researching compounds for catalysts for years at MSU. Weisenstein became a member of the ZAF team and developed a special formula for the perovskite used in the battery catalyst, which was essential for the creation of an efficient bi-directional cathode. Today Weisenstein is a senior scientist at ZAF.

That is part of the “serendipity” Brost refers to in the ZAF research that has led to today’s prototype. He says he’s been surprised at how fast their research has developed – a matter or a year or two as opposed to typically three to five years. “It evolved as a very simple but very elegant system,” he says. “The individual components are interesting enough, but putting them together in this trinity of technologies will give us a very superior commercial product.”

Thomas Zawodzinski, Governor’s Chair in Electrical Energy Storage at the University of Tennessee Knoxville, has verified the general claims made by Brost and Wilkins. “They’ve got something that works. They definitely have a rechargeable battery,” he said in an interview, adding, “It’s always a question of efficiency.”

Zawodzinski, who holds a chair at Oak Ridge National Labs, says he considers ZAF in the early prototyping stage — “a process of continual improvement of these materials.” He says he tested the ZAF battery in his lab and “we more or less validated the performance they’re showing.”

Zawodzinski is leading a team of researchers from Penn State, Case-Western University, and the University of Memphis to synthesize new materials for use in the ZAF electrolyte.

Brost reports that they are testing for conductivity and water chemistry and trying various materials developed by Zawodzinski’s team in their batteries. “We’re looking for a long-life battery that is robust at different temperatures, humidities, and latitudes,” he says.

ZAF’s commercialization model is to license its technology, and they are in talks with several companies. Brost predicted commercialization for small applications, such as hearing aides, will take about a year and EV batteries three to five years.

ZAF and ViZn Energy, located in Columbia Falls, Montana, have kept a low profile and operate through funds provided by investors. Together they employ about 70 people.

About the Author: Joan Melcher is a freelance writer and editor who focuses on energy and the environment. Her stories have appeared in Pacific Standard, BioCycle, High Country News, and chinadialogue.com.

Keep up to date with all the hottest cleantech news by subscribing to our (free) cleantech newsletter, or keep an eye on sector-specific news by getting our (also free) solar energy newsletter, electric vehicle newsletter, or wind energy newsletter.

Print Friendly

Share on Google+Share on RedditShare on StumbleUponTweet about this on TwitterShare on LinkedInShare on FacebookPin on PinterestDigg thisShare on TumblrBuffer this pageEmail this to someone

Tags: , , , , ,


About the Author

is many, many people. We publish a number of guest posts from experts in a large variety of fields. This is our contributor account for those special people. :D



  • Peter

    Does anybody know what a bi-directional air cathode is? I know the meaning of bi-directional but not in this context.

    btw. a 400 Wh/kg lithium-ion battery is already developed.

  • Peter

    Does anybody know what a bi-directional air cathode is? I know the meaning of bi-directional but not in this context.
    btw. a 400 Wh/kg lithium-ion battery is already developed.

    • Didier Guillonnet

      bi-functional = can be used for Charging and Discharging.
      A “regular” air-electrode is destroyed when you use it for recharging.

  • Tim Friar

    …..and pigs fly.
    There are liars, big liars and battery developers.
    Even if they solved the dendrites and the deterioration of the oxygen electrode – they still have the show-stopping issues of dryout, carbonate crystals in the cathode, zinc gassing and the resultant hydrogen bubbles. Besides, with solid electrolyte they may get enough power to light a flashlight. (note there is no DOD or W/Kg)
    Every 12 months a new team will have “solved” the issues of rechargeable zinc-air. Been there, done that…….and watch out for low flying pigs.

    • Didier Guillonnet

      Indeed, this “solid electrolyte” should create many problems…
      It would be worth having a look at their patents…

  • Bob_Wallace

    Joan, thanks for staying involved with your article. Too many authors drop and abandon.

  • Renewable Energy

    Here’a question: Where is their funding ocming from? They have 70 people on the salary, no sales, and no government funding. Other companies that have received milions in government funds haven’t succeeded, but this Montana team has created with private funding what others have failed at?
    Something smells fishy to me.

    • Joan Melcher

      I’ve experienced the same sort of skepticism when pitching this story. First, as Brost explained to me, they have a different model than most start-ups. They haven’t been interested in going after government funding and haven’t needed to. Investors have provided the funds. You either believe them or you don’t. I’ve followed them for a couple of years and find them quite credible, so I choose to believe them. Time will tell.

  • Joan Melcher

    Thanks for pointing out the typo and omission. These will be corrected. You may be right in saying I’m unit-challenged, a state often associated with writers.

  • Bob_Wallace

    Just some comparisons -

    EOS Systems is getting ready to install their zinc-ion batteries on multiple grids around the world. They seem to be manufacturing.

    They claim 10,000 full cycles/30 year life, $160/kWh, non-toxic, non-flammable electrolyte and materials. They are working on a EV version. I’m not finding a Wh/kg number.

    http://www.eosenergystorage.com/utility#sthash.lX3XkMBt.dpuf

    Envia claims a 400 Wh/kg lithium-ion battery at $125/kWh. As of a year ago they were demonstrating 600 cycle 80% capacity. A 200 mile range EV that needed a not-expensive (sub $3k) battery swap somewhere over 120,000 miles would likely to be a winner. Apparently GM is track testing their batteries.

    http://enviasystems.com/innovation/

    http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/energy_storage/es137_lopez_2012_p.pdf

  • K

    “with resources totalling 1.9 billion worldwide”. Teaspoons? Tons? Tonnes? Stone?Years of supply at current demand? Any projections as to whether this will have any economic effect on zinc prices? I would guess unlikely as zinc is already used in batteries in a different form

    • S.Nkm

      The author appears to be unit-challenged.

  • Bob_Wallace

    At 400Wh/kg that would be 2.9x the capacity of the LEAF’s 140Wh/kg battery.

    The LEAF has a ‘worst case’ range of about 60 miles so keeping battery weight constant it would have about a 170 mile range in cold weather with the heater blasting.

    And the LEAF has a highway range of 70 miles with the AC on, so this would give about 200 miles of highway driving.

    Only 500 recharges would limit battery life to 85k to 100k. Installing enough batteries to make it a 500 mile range car would mean a lot more space for batteries and a lot higher purchase price. 200 highway mile range is adequate.

    People might buy an EV knowing that they would have to install new batteries at ~100k if they also knew the replacement cost would be reasonable. I can’t find a price for the LEAF batteries, but a couple years ago a replacement pack was $10k and we know that battery prices have been dropping.

    Let’s, just for fun, assume they are down to $6k not. A ‘second life for your EV’ replacement would be, based on the 3x cheaper claim, a couple thousand dollars.

    I really don’t think people would find that off-putting.

  • S.Nkm

    Mh/kg?

    • Jouni Valkonen

      Turn “M” upside down. For comparison, Lithium-ion batteries has energy density 150–250 Wh / kg.

Back to Top ↑