British firm builds experimental iPhone 6 with hydrogen fuel cell

The only modifications include repurposing the headphone jack for refilling, and vents on the back to release small amounts of water vapour, according to The Telegraph, which was shown the prototype. A shipping product with the technology — not necessarily an iPhone — would have a dedicated slot for fuel cartridges, each containing enough powder to run a phone for about a week.

The Telegraph report contended that Intelligent Energy is "working closely" with Apple, although both companies refused to comment on the topic.

Intelligent Energy's corporate finance head, Mark Lawson-Statham, cautioned that a commercial product is "a couple of years out." He added that it's "about how quickly does our partner want to press the button and get on with it."

Most smartphones, including iPhones, use lithium ion batteries recharged via USB. Their battery life is typically weak though, forcing people to plug in once or twice a day.

Extending battery life has been a regular concern of Apple. Until now though, Apple's only known exploration of hydrogen has been a series of U.S. patents.