Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nanoparticle electrode for batteries could make grid-scale power storage feasible

24.11.2011
The sun doesn't always shine and the breeze doesn't always blow and therein lie perhaps the biggest hurdles to making wind and solar power usable on a grand scale.

If only there were an efficient, durable, high-power, rechargeable battery we could use to store large quantities of excess power generated on windy or sunny days until we needed it. And as long as we're fantasizing, let's imagine the battery is cheap to build, too.

Now Stanford researchers have developed part of that dream battery, a new electrode that employs crystalline nanoparticles of a copper compound.

In laboratory tests, the electrode survived 40,000 cycles of charging and discharging, after which it could still be charged to more than 80 percent of its original charge capacity. For comparison, the average lithium ion battery can handle about 400 charge/discharge cycles before it deteriorates too much to be of practical use.

"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, a graduate student in materials science and engineering who is the lead author of a paper describing the research, published this week in Nature Communications.

"That is a breakthrough performance – a battery that will keep running for tens of thousands of cycles and never fail," said Yi Cui, an associate professor of materials science and engineering, who is Wessell's adviser and a coauthor of the paper.

The electrode's durability derives from the atomic structure of the crystalline copper hexacyanoferrate used to make it. The crystals have an open framework that allows ions – electrically charged particles whose movements en masse either charge or discharge a battery – to easily go in and out without damaging the electrode. Most batteries fail because of accumulated damage to an electrode's crystal structure.

Because the ions can move so freely, the electrode's cycle of charging and discharging is extremely fast, which is important because the power you get out of a battery is proportional to how fast you can discharge the electrode.

To maximize the benefit of the open structure, the researchers needed to use the right size ions. Too big and the ions would tend to get stuck and could damage the crystal structure when they moved in and out of the electrode. Too small and they might end up sticking to one side of the open spaces between atoms, instead of easily passing through. The right-sized ion turned out to be hydrated potassium, a much better fit compared with other hydrated ions such as sodium and lithium.

"It fits perfectly – really, really nicely," said Cui. "Potassium will just zoom in and zoom out, so you can have an extremely high-power battery."

The speed of the electrode is further enhanced because the particles of electrode material that Wessell synthesized are tiny even by nanoparticle standards – a mere 100 atoms across.

Those modest dimensions mean the ions don't have to travel very far into the electrode to react with active sites in a particle to charge the electrode to its maximum capacity, or to get back out during discharge.

A lot of recent research on batteries, including other work done by Cui's research group, has focused on lithium ion batteries, which have a high energy density – meaning they hold a lot of charge for their size. That makes them great for portable electronics such as laptop computers.

But energy density really doesn't matter as much when you're talking about storage on the power grid. You could have a battery as big as a house since it doesn't need to be portable. Cost is a greater concern.

Some of the components in lithium ion batteries are expensive and no one knows for certain that making the batteries on a scale for use in the power grid will ever be economical.

"We decided we needed to develop a 'new chemistry' if we were going to make low-cost batteries and battery electrodes for the power grid," Wessells said.

The researchers chose to use a water-based electrolyte, which Wessells described as "basically free compared to the cost of an organic electrolyte" such as is used in lithium ion batteries. They made the battery electric materials from readily available precursors such as iron, copper, carbon and nitrogen – all of which are extremely inexpensive compared with lithium.

The sole significant limitation to the new electrode is that its chemical properties cause it to be usable only as a high voltage electrode. But every battery needs two electrodes – a high voltage cathode and a low voltage anode – in order to create the voltage difference that produces electricity. The researchers need to find another material to use for the anode before they can build an actual battery.

But Cui said they have already been investigating various materials for an anode and have some promising candidates.

Even though they haven't constructed a full battery yet, the performance of the new electrode is so superior to any other existing battery electrode that Robert Huggins, an emeritus professor of materials science and engineering who worked on the project, said the electrode "leads to a promising electrochemical solution to the extremely important problem of the large number of sharp drop-offs in the output of wind and solar systems" that result from events as simple and commonplace as a cloud passing over a solar farm.

Cui and Wessells noted that other electrode materials have been developed that show tremendous promise in laboratory testing but would be difficult to produce commercially. That should not be a problem with their electrode.

Wessells has been able to readily synthesize the electrode material in gram quantities in the lab. He said the process should easily be scaled up to commercial levels of production.

"We put chemicals in a flask and you get this electrode material. You can do that on any scale," he said.

"There are no technical challenges to producing this on a big-enough scale to actually build a real battery."

Huggins is a coauthor of the Nature Communications paper.

Louis Bergeron | EurekAlert!
Further information:
http://www.stanford.edu

More articles from Power and Electrical Engineering:

nachricht New creepy, crawly search and rescue robot developed at Ben-Gurion U
19.07.2018 | American Associates, Ben-Gurion University of the Negev

nachricht The role of Sodium for the Enhancement of Solar Cells
17.07.2018 | Max-Planck-Institut für Eisenforschung GmbH

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Global study of world's beaches shows threat to protected areas

19.07.2018 | Earth Sciences

New creepy, crawly search and rescue robot developed at Ben-Gurion U

19.07.2018 | Power and Electrical Engineering

Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says

19.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>