Published on November 29th, 2011 | by Glenn Meyers5
Stanford Researchers Explore Large-Scale Renewable Energy Storage
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.
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.