From the article:
"It's not a small improvement," Cui said. "It's a revolutionary development."
Citing a research paper they wrote, published in Nature Nanotechnology, Cui said the increased battery capacity was made possible though a new type of anode that utilizes silicon nanowires. Traditional lithium ion batteries use graphite as the anode. This limits the amount of lithium — which holds the charge — that can be held in the anode, and it therefore limits battery life.
The only problem i can see with this is forgetting to charge the devices that contain them. I already forget to charge my phone due to the battery lasting so long.