SanDisk offer a simple 2-in-1 solution for those of us who could use a little bit of extra memory storage, and a mid day power-boots, the iXpand Memory Case designed for the iPhone 6/6s in 32, 64, or 128GB storage capability, and 3 color variation. SanDisk also offers a dedicate app that will automatically make back ups of your photos and videos along with the SanDisk secure access. The extra battery pack is an add-on that would have to purchase separately, and it mounts directly to the iXpand Memory Case.
Buy: SanDisk iXpand case