Better Batteries for the Grid

I’ve written here a number of times about the quest to develop new battery technology.  Of course, we would all like our laptops, cell phones, and other electronic gizmos to go longer on a single battery charge, and better batteries would also be welcome for electric vehicles.   But one of the biggest potential markets for new types of batteries is the electricity supply industry; batteries could be used to help smooth out supply and demand fluctuations for the “smart grid”, and would make integrating alternative sources, like solar and wind power, easier.  Usage in the power grid has some different requirements: weight, for example, is not so much of a concern as it would be for a mobile device, but high capacity, low cost, and long service life are very important.

Technology Review reports that a research group at Stanford University, led by Yi Cui, a professor of materials science and engineering, has developed a new electrode material that shows early promise for making a better grid battery.

Researchers at Stanford University have now demonstrated a high-efficiency new nanomaterial battery electrode that lasts for 40,000 charge cycles without significantly losing its charge-holding capacity.

The battery chemistry envisioned is similar to that of current lithium-ion batteries; it employs the transport of sodium and potassium ions between the battery’s electrodes.   Sodium and potassium are, relatively speaking, abundant and cheap.  The electrolyte will be a water based solution of, for example, potassium nitrate, rather than the organic-solvent-based electrolytes used in lithium-ion batteries; this also should reduce costs.

The new electrode itself is made from reasonably common materials.

The researchers start with the pigment Prussian Blue, an iron and cyanide compound. They replace half the iron with copper, and make crystalline nanoparticles of the resulting compound, which they coat on a cloth-like carbon substrate.

The research team says that the new electrode can retain 83 % of their capacity after 40,000 charge cycles.  By comparison, lithium-ion batteries last about 1,000 cycles, and lead-acid batteries a few hundred,

This research, interesting though it is, is just a first step.  The new electrode technology has so far been used only as a battery cathode; the team is working on modifying it for use as an anode, and on building a complete battery prototype.