“Today’s lithium-ion batteries typically rely on graphite anodes to offer a long lifespan. Rechargeable battery performance declines and eventually falls off a cliff (becomes unusable) due to those anodes repeatedly expanding and contracting as lithium ions migrate during the cycle of charging and discharge,” Matthew Humphries reports for Geek. “Lithium compounds build up on the electrodes during this process then break off during the expansion and contraction. This exposes the surface of the electrode and over time decomposes it to the point of failure.”
“A better alternative to using graphite for the anodes would be aluminum, but aluminum expands and contracts too much during each cycle. If scientists could stop that happening, we’d have much better performing batteries,” Humphries reports. “Dr Wang Changan of Tsinghua University and Dr Li Ju of MIT have been working together to stop the oxide coating that forms on the surface of aluminum nanoparticles when it is exposed to air. Their idea was to soak the nanoparticles in a sulfuric acid and titanium oxysuplphate mix, which would dissolve the aluminum oxide and replace it with titanium oxide.”
“Achieving the new outer coating required a set time of soaking. The accident occurred when Wang and Li forgot to remove one batch of the nanoparticles from the soaking process,” Humphries reports. “That batch ended up soaking for several hours longer than intended with the result being the sulfuric acid and titanium oxysulfate mix leaked into the 50nm nanoparticles and dissolved some of the aluminum inside. What this left was a nanoparticle with a 4nm outer shell of titanium hydroxide and an inner 30nm ‘yolk’ of aluminum… The extra long soak meant the anodes did not expand and contract, in fact they created a battery that over 500 charge/discharge cycles retained up to four-times the capacity of the equivalent graphite anode batteries. These batteries last considerably longer in terms of usable lifespan and, according to MIT, can hold up to three-times the energy.”
Read more in the full article here.
MacDailyNews Take: This reminds us of biologist Alexander Fleming who took a summer vacation from work in the lab investigating staphylococci. Upon his return on Sept. 3, 1928, as the story goes, Fleming found a strange fungus on a culture he had left in his lab — a fungus that had killed off all surrounding bacteria in the culture. Modern medicine was never the same after the discovery of Penicillin.
[Attribution: Cult of Mac. Thanks to MacDailyNews Reader “Fred Mertz” for the heads up.]