Virtually all of your gadgets use lithium ion batteries—but while they're the best you can hope for at the moment, new engineering means that pure lithium batteries are now a possibility, and they could double the life of your phone.
All batteries have three basic parts: an electrolyte to provide electrons, an anode to discharge them, and a cathode to receive them. Currently, lithium is only present in the electrolyte of batteries and not on the electrode because, during charging, lithium ions at the anode and cathode expand dramatically—causing the electrodes to break down.
As a result, scientists have tried but failed to make lithium electrodes—knowing that, if they could, they could boost efficiency by two, three or even four times. Now, in research published in Nature Nanotechnology, Stanford University researchers have added a protective layer of interconnected carbon domes on top of their lithium anode — providing enough protection to avoid the usual damage. Just 20 nanometres thick, the protective surface allows the lithium electrode to work properly, but deforms with it as it expands to keep it from breaking down. Guangyuan Zheng, one of the researchers, explained:
"[W]e found a way to protect the lithium from the problems that have plagued it for so long... In practical terms, if we can improve the capacity of batteries to, say, four times today's, that would be exciting. You might be able to have cell phone with double or triple the battery life or an electric car with a range of 300 miles that cost only $25,000—competitive with an internal combustion engine getting 40 mpg."
But there's one hitch: to be commercially viable, a battery must have a coulombic efficiency of 99.9 per cent or more. The best lithium electrode batteries in the past had boasted efficiency of 96 per cent efficiency, dropping to less than 50 per cent in just 100 cycles; this one, by comparison, achieves 99 per cent efficiency even at 150 cycles. In other words, it's hardly a commercial reality, but it is the best shot yet at a pure lithium battery and the efficiencies that come with such an advance. [Nature Nanotechnology via PhsyOrg]
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