The format of the serial number printed on the hose that connects the battery to the motherboard of the device is indeed similar to the format used by Apple (820-4545-03 820-3230-03 for the battery and for that iPhone 5). Note also that this hose connector fits perfectly to that found on the motherboard of the iPhone 6 to 4.7, and 5.5 inches
At this point in time, it's believed that the 2,915 mAh battery is intended for the 5.5-inch iPhone 6; whereas, a smaller 1810 mAh battery is predicted for the 4.7-inch model. The iPhone 5s battery has a capacity of 1,560 mAh.
Earlier today a lengthy 7 minute video leaked that allegedly shows the iPhone 6 in action. Watch it here. Apple is expected to unveil the iPhone 6 on September 9th. We'll have plenty of coverage before, during, and after. You can follow iClarified on Twitter, Facebook, Google+, or RSS for updates. The iClarified app can be downloaded from the App Store for free!