San Francisco, Apr 29 (IANS): Cupertino-based tech giant Apple has filed a patent about working on flexible batteries which may ultimately be used in foldable iPhones and iPads.

It revealed that Apple is looking at different ways to fit battery cells in unusual shapes, such as cylinders, by making the batteries capable of bending and flexing, PhoneArena reported on Tuesday.

"In addition to taking up space, the batteries are also often quite rigid, often making placement of the batteries in portions of a device designed to bend impractical. For this reason, it would be desirable to have a flexible or semi-flexible battery for use with a portable electronic device," notes the patent documentation.

Rumours of a foldable iPhone have popped up on numerous occasions over the past few years. Apple has also filed for patents for a flexible display with touch sensors and portions that open and close like a book, as well as a flexible iPhone that could be folded in half and grip a person's clothes.

According to the consumer survey, more than a third of Apple customers showed interest in paying as much as $600 extra for a foldable iPhone.

Earlier in 2018, the iPhone-maker had secured a patent for foldable phone that focussed on a flexible hinge and the use of a fabric for its housing.