Charge your smartphone in SIX minutes: 'Yolk and shell' battery technology could end long waits while devices power up It is a problem almost everyone with a smartphone has faced at some point “ their device is almost out of battery and there is not enough time to charge it before heading out for the evening.
But a new type of battery made with tiny capsules filled with aluminium could soon mean smartphone users will be able to fully charge their device within six minutes of plugging it in.
The battery also has four times the capacity of current lithium ion batteries and degrades less over time.
This 'yolk and shell' overcomes previous problems experienced with using aluminium in rechargeable lithium ion batteries in the past.
While current lithium ion batteries use graphite “ a form of carbon “ it has a limited storage capacity.
Metals like lithium can store 10 times as much energy but are unstable and can often catch fire or short circuit.
Aluminium has been known to be another high capacity material but it can double in volume and shrink again as it is charged and discharged.
This repeated shedding and reforming of the 'skin' layer consumes lithium and reduces the battery's capacity over time.
By encasing the aluminium yolk inside a shell, however, researchers at the Massachusetts Institute of Technology and Tsinghua University, Beijing, found the aluminium could expand and shrink freely.
Professor Ju Li, a materials scientist at MIT who led the work, said: 'We made a titanium oxide shell that separates the aluminum from the liquid electrolyte.
'We came up with the method seredipitiously, it was a chance discovery.'
Writing about their results in the journal Nature Communications, the researchers explained the shell can keep the aluminium protected from the electrolyte in the battery while also allowing it to expand and contract.
Measuring just 50 nanometres across, the aluminium yolk is surrounded by a shell of titanium dioxide of just three or four nanometres thick.
When these nanoparticles are used as the anode in a lithium ion battery, the researchers found it had a storage capacity of 1.2 ampere-hours per gram.
A lithium ion battery using graphite has a storage capacity of 0.35 ampere-hours per gram.
The researchers also found they could achieve very fast charging times with the 'yolk and shell' battery, with a full charge in just six minutes.
However, this reduces the capacity of the battery by half to 0.66 ampere-hours per gram, still tice that of graphite batteries.
Professor Li said: 'It's probably the best anode material available.'