Clean Power

Published on November 29th, 2011 | by Glenn Meyers


Stanford Researchers Explore Large-Scale Renewable Energy Storage

November 29th, 2011 by  

One of the biggest hurdles for integrating renewable energy from solar or wind sources comes from the question of storage – how can power be stored for times when the wind doesn’t blow or the skies are overcast?

Researchers at Stanford University are addressing this headlong and have reported the development of a new high-power electrode that is cheap, durable and efficient. If development continues as hoped, this discovery might potentially foster the manufacture of batteries large enough to provide for economical renewable energy storage on the grid.

Said electrode was made using crystalline nanoparticles from a copper compound, copper hexacyanoferrate. The atomic structure of the crystals found in the new electrode has an open framework that allows ions to move in and out without damaging the electrode.

Laboratory tests show this electrode survived 40,000 charging/discharging cycles. Following that activity, the electrode could still be charged to 80 percent of original capacity. By comparison, today’s average lithium-ion battery can only handle approximately 400 charge/discharge cycles before deteriorating. And because the ions can move so freely, the charging and discharging cycles of the new electrode are extremely fast.

“At a rate of several cycles per day, this electrode would have a good 30 years of useful life on the electrical grid,” said Colin Wessells, lead author of the study and a graduate student in materials science and engineering.

The Stanford team’s paper describing their research was published this week in the journal Nature Communications.

Yi Cui, Wessells advisor and Stanford professor of science and materials engineering, added his perspective on the discovery: “That is a breakthrough performance – a battery that will keep running for tens of thousands of cycles and never fail.”

Energy density has been a major focus for researchers working to build better lithium-ion based batteries for use in portable electronic devices like mobile phones and laptop computers. Cost is also a huge factor in developing energy storage solutions for the grid.

As some of the components used in lithium-ion batteries are expensive, scaling them up to a point where they could be used in the power grid isn’t economical. Instead of the organic electrolyte used in lithium-ion batteries, The Stanford researchers used a water-based electrolyte, which Wessells says is “basically free.”

However, according to New Energy and Fuel, more development work needs to be undertaken on this project. As it turns out, the new electrode’s chemical properties are only usable as a high voltage electrode. Batteries need two electrodes – a high-voltage electrode for the cathode and a low-voltage electrode for the anode – in order to create the voltage difference that produces electricity. Researchers will need to find another material to use for the anode before building an actual battery. The team reports they are already investigating various materials and have some promising candidates.


Photo: bterrycompton


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About the Author

is a writer, producer, and director. Meyers was editor and site director of Green Building Elements, a contributing writer for CleanTechnica, and is founder of Green Streets MediaTrain, a communications connection and eLearning hub. As an independent producer, he's been involved in the development, production and distribution of television and distance learning programs for both the education industry and corporate sector. He also is an avid gardener and loves sustainable innovation.

  • Andy G

    Someone get these guys in touch with the MIT folks who invented the Li-ion flow battery this summer. Multiple breakthrough innovations in batteries could give us the competitive advantage we desperately need to jump start job growth and further the transition to renewables.

    • Anonymous

      I hope/imagine they are all keeping an eye on each other and collaborating where it makes sense to. But good call..

  • Reality

    The lithium ion batteries in both the Nissan Leaf and Chevy Volt are warrantied to maintain 80% of their capacity for 10 years. This is 3,650 charge-discharge cycles (far more than the claimed 400). They are already in production and not just a professo’rs estimate of some future device.

    • Anonymous

      Nissan is guaranteeing their battery for 8 years OR 100,000 miles.

      If you did a full charge/discharge, drove 100 miles, each day you would use up your guarantee in 1,000 cycles/days.

      The ‘8 year’ part assumes that many/most people will not drive that many miles a year but will string out their charge cycles over more years.

      The Volt is also 8 years OR 100,000 miles.

      Lithium-ion are better than lead acid, but they aren’t the 5,000 – 40,000 cycles of what it looks like sodium-ion batteries will give us. Unfortunately sodium-ion batteries are not as lightweight and small as lithium-ion so it looks like we won’t get their higher cycle rates in EVs.

  • Anonymous

    Aquion seems to be getting to market first with a sodium-ion storage battery. They’re in the plant establishment phase right now with $30 million startup funds and expect to be producing next year or early 2013.

    Their battery has been tested in independent labs at 5,000 100% DoD (depth of discharge) cycles and have stated that they think they can raise the cycle number to 20k as they go along.

    High tolerance to battery mismatch.

    No self discharge or problems in high heat conditions.

    Smaller and lighter than lead acid. Easier/cheaper to ship.

    100% recyclable.

    About the same price point as lead-acid batteries but capable of much deeper discharge and many more cycles. This makes them a fraction of the cost of lead-acid batteries per cycle.

    Only 5,000 cycles would mean that these batteries could move nighttime wind to day peak hours every day for over 13 years. Stanford’s 40,000 cycles is a mind-blower. Looks to me like the problem of intermittent wind and Sun might be soon to fall.

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