PALO ALTO, Calif. -- One of the biggest challenges Apple faced in designing its watch was the battery life.
The phones and watches of the future may have a different kind of battery and researchers are currently working on it right now at Stanford University.
"We've designed it so that it's simple to charge at night," said Apple CEO Tim Cook during the unveiling of the Apple Watch in September 2014.
And by that, he means every night. Behind the tiny face of the Apple Watch is an equally tiny battery. It's a smaller version of the hard rectangular batteries found in cell phones.
Stanford University researchers have created a battery that's thin and flexible enough to fit inside a watch band. They hooked it up to a bright green LED and even when it's bent the LED still turns on.
What's inside the battery isn't exotic.
"This is a piece of aluminum foil. It's very shiny and you have it in your kitchen," said a Stanford researcher.
The dark foil is graphite. Both are cheaper and safe than what's in today's batteries.
"You can drill a hole through it and the battery will still work," said Michael Angell, a Stanford graduate student.
As airlines crack down on shipping lithium batteries, which can explode, almost nothing can make this new battery catch fire.
"Several companies expressed interest already to potentially license the technology and make products out of them," said Hongjie Dai, a Stanford University chemistry professor.
Some of the promise in these batteries lies in how similar they are to existing lithium technology. For one thing they can be charged using the same chargers. For another, they're manufactured in much the same way.
"A good factory can, can make it very soon, because it's very simple, really," said Yingpen Wu, a Stanford postdoctoral student.
But there are things to work out.
The third ingredient is a liquid salt that's still kind of expensive and right now, these batteries don't last as long as lithium on a single charge, but you can recharge them and recharge them.
"This guy right behind me is actually on its six-thousandth cycle," Angell said.
In a cellphone, that battery could keep working like new for 10 years.
"The fastest we have charged an aluminum battery is actually under a minute," Dai said.
Imagine that in an electric car and if you like being green, consider this, aluminum is everywhere.
"I could literally cut up an a piece of aluminum can right now and make a battery for you," Angell added.
Stanford researchers develop safe, fast-charging battery