With a 2500mAh cell, Tylt's Energi Sliding Power Case ($100) is the highest capacity single battery case we've yet come across for the iPhone 5. It also features a design that's not exactly like anything we've seen before: the battery sled comes packed with two shell-style cases; one is black, and the other blue, green, or red depending on the bundle you purchase. When battery power isn't needed, you can use a shell on its own, and then when it comes…
