A new battery technology may pave the way for cheap, long-lived power storage that can quickly pump electricity into the grid to compensate for fluctuating renewables like wind and solar.

Developed by Yi Cui and colleagues at Stanford University in California, the battery's key advantage is its electrodes, which can run for a thousand charge cycles without degrading. Battery electrodes typically degrade over time as ions in a battery cell repeatedly slam into them and are ripped away again.

By coating the negatively charged cathode in copper hexacyanoferrate and using an anode made of activated carbon and a conductive polymer - compounds that allow electricity-carrying ions to move easily in and out - the team were able to build a prototype battery with electrodes that didn't lose capacity over time.


The new electrodes sandwich a liquid solution of positively charged potassium ions, a battery design that was invented only in 2004 using conventional electrodes. As in a standard battery, charged particles are driven towards the positive electrode during charging, flowing back to the negative electrode to provide current during discharge. The researchers write that their battery's components are cheap and commercially available.

Most energy-storage technologies are too expensive or inefficient to be widely useful in backing up wind and solar power sources, the researchers say.


"Virtually all of the energy-storage capacity currently on the grid is provided by pumped hydroelectric power, which requires an immense capital investment, is location-dependent and suffers from low energy efficiency," the team write.

Currently, the world's most powerful battery is in Zhangbei, Hebei province, China (above). It can hold 36 megawatt-hours of energy, and is used as a backup to a 140-megawatt solar and wind power installation. [Nature Communications]

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