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. ®
... I nearly had a cardiocirculatory collapse imagining ol' Rupert involved in serious research.
Isn't a limit for fire. It's a limit above which most jurisdictions require full electrical training - and with good reason.
It's also about as high as you can go without getting zapped off exposed wiring if your hand goes across it(*) - and there's a lot of exposed wiring in a telephone exchange MDF (especially the old-school ones)
(*) It still hurts if you have wet hands.
If you're storing for power distribution/inversion/etc then strings up to 600V are common but require _extreme_ care. DC isn't nearly as forgiving as AC(**) when things go wrong, which is part of the reason there aren't many 250/600V DC installations anymore (most of them went away in the 1930s)
(**) Edison was killing about 5 linemen a week on his "safe" 110VDC lines at the same time as he was decrying Tesla's AC system as being unsafe and demonstrating by electrocuting stray dogs.
The batteries in a lot of hybrids run to 600+VDC. Fire services and other emergency callout people are having to go through a bunch of training to ensure they appreciate the hazards involved and the criticality of ensuring the battery pack is isolated before attempting crash rescues.
FWIW: Properly maintained lead-acid traction batteries aren't particularly toxic and they're 95% recyclable at end of life - which is a _long_ time if properly maintained. If sodium batteries can go 20-30 years then they'll be a good competitor.
Didn't Edison also electrocute an elephant in New York, to prove how unsafe AC was? Dishonest, yes - but still an amazing publicity stunt.
Not that he was a weirdo or anything...