The Unihertz Tank is a 22,000 mAh battery in a smartphone and can last days on stand by, maybe weeks! Not an AD but check it out here! www.unihertz.com/products/tank
Another good phone with 22k mh battery is coming soon called Doogee VMax. It has a better camera and speakers, better screen 120hz although it's a little smaller and it's 5G