Apple braces to release its latest device iPhone 6 with larger screen and an upgraded battery that provides better performance than any other handset.

A recent survey conducted by RBC Capital Markets' analysts suggested consumers have been expecting an improved battery life from Apple's new device, iPhone 6.

A report from a Chinese Web site as cited by Cnet, the much awaited iPhone 6 will have a larger screen with 4.7-inch and would also receive a 15 percent boost in battery life per charge.

Apple will be launching iPhone 6 with two new devices: one with a 4.7-inch screen and the other with a 5.5-inch display screen. The 4.7-inch iPhone 6 is expected to last longer than iPhone 5S on a single battery charge. Earlier, Apple had increased the battery performance at 8 percent on iPhone 5S from iPhone 5.

Chinese Web site IT168 reported the 4.7-inch iPhone would be using an 1800 mAh battery and still will be thinner in design. There were rumors claiming the next-generation iPhone will be thin in size as compared to its previous models.

The 5.5-inch iPhone 6 would be coming with 2500 mAh battery which, according to AppleInsider, will have a 60 percent rise in battery performance as compared to iPhone 5S.

Although the two new devices are larger than the 1,560 mAh battery in iPhone 5S, it is set to have an ultra slim design. MacRumors reported the larger screens on iPhone 6 creates heavy volume for the bigger batteries along with maintaining a slim profile, but the displays often require an increased battery to be compatible with the high resolution.

Also, the Apple's software and hardware integration also contributes to the overall battery life. It is expected the performance of the battery may be better than the hardware specs as the company announced improvements that were added to iOS 8.

iPhone 6 is expected to be released by Apple in September and may launch both its 4.7- and 5.5-inch devices at the same time. It could feature faster A8 processor, upgraded touchID scanner and updated camera with image stabilization quality.

The Cnet further reported the current smartphones come with more features which easily drop the battery life of the device. The greatest challenge a smartphone company would face is to keep the battery performance high while the devices are slim with all the high-end features.