"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.