File:Expanded lithium-ion polymer battery from an Apple iPhone 3GS.jpg - Wikimedia Commons
Apple's iPhone slowdown: Your questions answered - CNET
IBESTWIN Battery for iPhone X,3800mAh Upgraded High Capacity Replacement Battery for IP X (A1865, A1901, A1902) with Tool kit Adhesive and Manual, High Capacity Battery 0 Cycle-3 Years Warranty
Third-Generation iPhone SE Teardown Reveals Larger Battery Capacity and Snapdragon X57 Modem - MacRumors
Original Battery replacement for iPhone 3GS
How to Calibrate Your iPhone's Battery | Appledystopia