Relative to the other features on our smartphones -- storage capacity, camera resolution -- battery life has not progressed much in recent years. As a matter of fact, there hasn't been a truly significant breakthrough in consumer battery technology in decades.
As Jules Suzdaltsev explains in today's DNews report, that's not likely to change in the near future, but there may be a long-lasting light at the end of the tunnel.
First, let's take a look at what we've got. Nearly all rechargeable modern batteries are based on lithium-ion technology. They generate electrical current from the movement of lithium ions between electrodes. And for this purpose, lithium is great. It's the least-dense metal, with the highest energy-to weight ratio of anything else we could potentially be using.
But lithium batteries aren't built to last. At least, they don't last as long as we'd like them to. Here's a statistic for you: The average lithium-ion smartphone battery is generally expected to last between 300-500 charge cycles. (Bear in mind this refers to a full-discharge cycle, taking the battery from zero percent all the way back up to 100 percent.) Recharge efficiency degrades gradually, and can be accelerated by overheating and other factors.
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While battery capacity isn't getting much better, battery life is continuing to improve. That's because effective battery life is really capacity divided by consumption. For instance, the new iPhone 7 processor chip uses only two-thirds as much power as the previous iteration, while reportedly increasing performance by 40 percent.
Now for the good news: Earlier this year, researchers from the University of California, Irvine (UCI) accidentally invented a battery that, for all practical purposes, never dies. The breakthrough involves the use of nanowires, highly conductive filaments that are thousands of times thinner than a human hair. Nanowires are great for moving electrons around, but they're extremely fragile and scientists have been unable to get them to work with traditional batteries.
The UCI team appears to have solved the problem by coating gold nanowires in a manganese dioxide shell and encasing the assembly in an electrolyte gel. (Why didn't we think of that?) The upshot: Researchers charged up the test device 200,000 times over three months without any loss of capacity or power and without fracturing any nanowires.
This could be a Very Big Deal indeed, but the entire initiative is still in early research phase, so it will be a while before we see anything play out. If the math holds up, these new nanowire batteries could last up to 400 years.
-- Glenn McDonald
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