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Arndt Remhof's team has developed a solid electrolyte that facilitates good mobility of sodium ions at 20 degrees. This last point is crucial: ions require a source of heat in order to move, and inducing a reaction at room temperature poses a technical challenge. The electrolyte is also non-flammable and is chemically stable up to 300 degrees, which addresses the various safety concerns associated with lithium-ion batteries. Hans Hagemann's team at the University of Geneva has been working in parallel to develop cheaper technology for the production of this new solid electrolyte.
Unlike lithium, there are huge reserves of sodium: it's one of the two components of table salt. "Availability is our key argument", says Léo Duchêne of Empa and first author of the research paper. "However, it stores less energy than the equivalent mass of lithium and thus could prove to be a good solution if the size of the battery isn't a factor for its application."
Magnesium: the perfect but complex material
The same team has also developed a solid magnesium-based electrolyte. Until now, very little research had been done in this field. The fact that it is much more difficult to set this element in motion doesn't mean that it is any less attractive: it's available in abundance, it's light, and there's no risk of it exploding. But more importantly, a magnesium ion has two positive charges, whereas lithium only has one. Essentially, this means that it stores almost twice as much energy in the same volume.
Some experimental electrolytes have already been used to stimulate magnesium ions to move, but at temperatures in excess of 400 degrees. The electrolytes used by the Swiss scientists have already recorded similar conductivities at 70 degrees. "This is pioneering research and a proof of concept," says Elsa Roedern of Empa, who led the experiments. "We are still a long way from having a complete and functional prototype, but we have taken the first important step towards achieving our goal."
The energy density of a magnesium electrolyte would solve the EV range problem, if it is double lithium's.
(Score: 2) by VLM on Wednesday May 03 2017, @06:01PM
Obviously, the discrepancies likely lie in the supporting chemistry - batteries are far more complicated than ionized metal bricks.
Oh agreed totally. Just in context of why would the chemist have a hand-wavy most of the time generally thing going on about atomic numbers vs volume of a mole (mole as in 6e23-somethings not the garden variety).
In one line without any explanation is summarizes to as atomic number goes up the mass of a mole goes up like two orders of magnitude while the density only goes up one order of magnitude so the ratio being the volume, generally speaking a mole of higher atomic number stuff will be both denser and physically larger than lighter stuff. Or the density IS increasing, but at a slower rate than the mass is increasing.
This comes up in those daydreams or sci fi movie plots about "sure atomic numbers immediately above 90 or have been radioactive, but what if there was an island of stability for super atoms with atomic number 200 or whatever" Well you can predict based on trends if there were a stable atom with a number of a couple hundred a gram-molecular-weight or whatever the cool kids call a mole today would be the size of a construction brick and it would probably have a density of like 100 g/cc which would certainly be mildly impressive. Picking up a little sugar cube of it would be like picking up a supermagnet stuck to a fridge, I can't get a grip did someone superglue this Fing thing to the lab bench?