Energy Storage

Published on November 24th, 2011 | by Nicholas Brown


40,000 Cycles — Nanotechnology Catapults Battery Technology Forward, Once Again

November 24th, 2011 by  

Zinc-Air Batteries

Yi Cui, a Stanford University professor of materials science and engineering, has led researchers to yet another breakthrough in battery technology, but this time, it is not lithium-ion.

For those that don’t already know, electric vehicles need batteries with a low cost and a long lifespan, and solar and wind power plants can benefit significantly from batteries like that as well. Storing solar and wind power for later use not only facilitates selling it at any time of day with no backup generators, but it eliminates reliability issues and fluctuations in electricity generation.

Stanford University researchers have demonstrated a battery technology that is able to retain 83% of it’s charge after 40,000 cycles. (1 cycle is 1 charge and 1 discharge.) Lead acid batteries only last a few hundred cycles, and lithium-ion 1,000.

Please note that the cycle life of batteries is not the same as their shelf life. Some batteries, such as li-ion self-degrade even when not being used. Lithium-ion batteries would last 19 years if they did not self-degrade, due to the fact that they have a cycle life of 1,000 cycles, assuming that they are cycled once per week.

This new battery technology is similar to lithium-ion batteries but can use either sodium or potassium ions instead of lithium ions. Sodium and potassium are much more abundant and cheaper than lithium.

What the researchers did was start with a pigment called “Prussian Blue,” which is a compound of iron and cyanide, and they replaced half of the iron with copper, then they manufactured crystalline nanoparticles of the compound. Then they coated it on a cloth resembling carbon substrate. Then, finally, they submerge it in an electrolyte solution called potassium nitrate.

The electrodes exhibited 99% efficiency. “You want the voltage you put in during charging and the voltage you take out during discharge to be same,” Cui says. “Compared to any other battery material, this is absolutely the best.”

This does have a drawback for weight-sensitive applications such as electric vehicles, though: this has an energy density of only 60 mAh per gram. Apart from that, this is definitely a technology I want to keep an eye on. Power plants are not weight-sensitive.

Related Articles:

  1. Apple Demonstrates Energy-Efficient MacBook Battery at MacWorld
  2. Ordinary Pencil Offers Solution for Elusive Lithium-Air Battery
  3. Eos Rechargable Zinc-Air Battery: Energy Storage “El Dorado?”

h/t Technology Review | photo via Voxphoto

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About the Author

writes on CleanTechnica, Gas2, Kleef&Co, and Green Building Elements. He has a keen interest in physics-intensive topics such as electricity generation, refrigeration and air conditioning technology, energy storage, and geography. His website is:

  • Francoveracruz

    can we let battery with cyanide in hand of public? just with the pH of vinager HCN can evolves!!!

  • Anonymous

    At this point they have a 40,000 cycle cathode. They need to develop the anode before they have a fully functioning battery.

    A different company is going into production with a sodium-ion battery which has been tested at 5,000 cycles and they think they can push to 20,000 cycles.

    Aquion is scouting sites for their first factory and they expect to be in production next year. They claim that their battery will be manufactured for the same amount as lead-acid batteries, but be greatly superior. (And they’ve secured $30 million start up funds.)

    Aquion claims 5,000 100% depth of discharge (DoD) cycles. Deep cycle lead acid batteries are generally rated at no more than 500 50% DOD cycles.

    If my math hasn’t failed me then an Aquion battery will give you –
    1kWh storage x 100% x 5,000 cycles = 5,000kWh useful life.

    And a deep cycle lead acid deep cycle will give you-
    1 kWh storage x 50% x 500 cycles = 250kWh useful life.

    If those numbers hold then the sodium-ion battery is effectively 20x cheaper than a lead-acid battery and would seem to solve the renewable energy storage problem. If Aquion can push their technology toward 20,000 cycles or Cui can develop a good anode then I think we can put a marker on the end of the fossil fuel era.

    • Anonymous

      Let me see if I can illustrate the value of inexpensive storage…

      I’m off the grid, mostly solar with some gas generator backup. I’ve got my electricity usage down to somewhere between one third and one half of the average US home. (Cook and heat water with propane, heat with wood, don’t need AC, all CFL/LED lights, etc.)

      I use a dozen deep cycle “golf cart” batteries to store solar/gas energy for the hours the sun isn’t shining. They cost me about $2,000 and last 5-7 years. In order for a utility company to put enough lead-acid storage in place to serve the average house with wind/solar power around the clock would probably cost $6,000 and drive up the cost of power by $100 a month.

      If Aquion can produce storage at 20x less then that number drops to an insignificant $5/month.

      With really cheap storage (20,000 or 40,000 cycles would take costs to no more than $1.25/month) there would be no reason to not power our grid with nothing but renewables.

      Wind is already one of the two cheap (new generation) ways to provide electricity. Natural gas is the other and the price of NG will rise. Solar is now close to or below TOU rates for the hours when the Sun shines. Solar will likely drop to being as cheap as wind over time.

      If you could get all the electricity you wanted from cheap wind and solar why would you tolerate coal burning?

    • Dcard88

      I agree with everything, but, what wopuld be the use for a battery life of more than 20K cycles? I cant think of anything that would need to be recharged more than once a day. Even at 10x per week, 20K cycles is a 40 year life. Hows a battery maker to make any money without ‘built in obsolescents’? If I were designing a battery, I would not make it last longer than 10K cycles if it added any cost.

      • Anonymous

        If battery performance/prices reach the point where we use batteries as ‘the’ storage method for renewables the market will be so large that no one is going to be worried about producing a product that lasts a long time.
        The manufacturer is going to get so rich that they won’t care if their business largely goes away in fifty years. The ten generations following them won’t be able to burn through what they will make in the initial fifty years.

        Looking at what is happening in battery technology advances it doesn’t seem like it’s going to cost more to make a 5k cycle battery than a 40k cycle battery. It’s all about how the cathode and anode are manufactured, not dependent on a lot of expensive materials. In fact, some of these batteries are using very inexpensive materials so it all comes down to perfecting manufacturing technique.

        These are batteries designed for storage of large amounts of power, for grid use. It’s easy to see how they might easily cycle a couple of times each day. Store up a lot of cheap wind energy at night and feed it back while waiting for the Sun to start producing. Store up solar to feed into afternoons. 20,000 cycles would give a battery good for around 30 years. If we could get a battery that lasted twice as long for the same amount, why not?

        It’s time we started talking about lifetime cost of power. Even though we
        tend to pay off generation/storage systems in the first 20 years of use
        most systems continue to produce much longer. Solar panels are still a bit
        expensive if you look at their 20 year cost of power, but not if you
        average their cost over 40-50 years.

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