Eesha Khare, 18, of Saratoga was given the Intel Foundation Young Scientist Award for creating a fast-charging device that takes a lot of charge quickly and holds a lot of energy.
And it can last for 10,000 charging cycles, compared with around 1,000 cycles for conventional rechargeable batteries, she said.
"My cellphone battery always dies," Khare told NBC News, explaining what inspired her to focus on energy-storage technology.
Researching her invention allowed her to work in her chosen area of nanochemistry, she said, "really working at the nanoscale to make significant advances in many different fields."
While so far her "supercapacitor" has only been used to power a tiny light-emitting device or LED, Khare said she envisions it inside smartphones and tablets, freeing up users from frequent trips to the nearest electrical outlet and hours of charging.
She was awarded her prize at the Intel International Science and Engineering Fair, conducted last week in Phoenix.