A reportfrom Taiwanese website Commercial News is claiming that Apple had planned to launch two models of the iPhone 6 this year, a 4.7-inch "traditional" device and a much larger 5.5 inch device - however issues with battery production may have put a major hold on the larger handset, with its release now looking increasingly unlikely this calendar year.
The issue seems to centre on the fact that Apple wants the device to remain as thin as possible, requiring a battery no thicker than 2 mm, but current battery technology typically comes in at around 2.8 mm, meaning that Apple will either have to relax its requirements (highly unlikely given the company's attention to aesthetic detail) or they'll need to wait until battery technology has caught up with its demands, potentially pushing plans for a larger device into next year, or beyond.
Interestingly, the report also claims that Apple has been referring to the larger device internally as the iPhone Air, which certainly sounds a lot better than iPhone 6 5.5 inch model.
The rumours will be a touch disappointing for iPhone fanatics who have been waiting for Apple to catch up on the screen size side of things for quite a while now. Typical Android handsets usually start at around 5 inches, so the iPhone 5s and 5c's 4 inch display seems positively miniscule by comparison - although a 4.7 inch display would definitely be a welcome improvement.