Unconfirmed rumor says iPhone 6s battery replacement program may be extended to iPhone 6 - 9to5Mac
Original Apple iPhone XR Mobile Battery with 2942mAh (With Warranty), Battery Type: Lithium-Ion, Voltage: 3.8
Amazon.com: Upgraded Battery for iPhone 6S, (2023 New Version) [3200mAh] Battery Replacement for iPhone 6S A1633,A1688,A1700 with Complete Professional Repair Tool : Cell Phones & Accessories
Amazon.com: REDISONA Small Portable Charger 4500mAh Power Bank with Built-in Cable, Mini External Battery Pack Compatible with iPhone 14/14 Pro/14 Plus/14 Pro Max/13/12/11/X/8/7/6 Airpods, White : Cell Phones & Accessories
iPhone 6s Plus Battery: Replacement Part / Repair Kit
iPhone 6, 6S, 6Plus and 7, 7Plus Battery Replacement and Upgrade THE RIGHT WAY - YouTube