Murdoch pitches battery for renewables
Portable power with a pinch of salt
Many proposals for storing energy from renewable installations like wind farms or large-scale solar energy involve high-temperature technologies like molten salt. Now, researchers from Murdoch University are talking up a more mundane wet-cell battery based on sodium ions.
If it could be commercialized, the water-based sodium-ion battery would also be much less toxic than the lead-acid batteries common in today’s small-scale remote solar installations.
As project co-leader Dr Manickam Minakshi of Murdoch’s School of Chemical and Mathematical Sciences says in this announcement, sodium’s chemical properties are similar to lithium (almost ubiquitous in the batteries of consumer devices). To have it work as an electrolyte in a battery, Murdoch’s work focused on devising the right materials to use as cathode and anode, since sodium ions are around 2.5 times the size of lithium ions.
Minakshi offered a “mesh filter” as an “imperfect analogy” of what happens in a battery, with ions passing from cathode to anode to provide the current. To accommodate the larger sodium ions meant identifying materials with the right “gaps” to allow ions to make the cathode-anode trip.
The group, which includes colleague Dr Danielle Meyrick, settled on manganese dioxide as the cathode, and an olivine sodium phosphate anode.
Unfortunately, the sodium’s ion size means a “salt-based” battery won’t be turning up in portable gadgets, but the researchers note that in static applications, a battery whose main materials are sodium, iron and manganese should be cheap enough for renewable installations in the developing world. ®