There are plenty of iPhone cases out there that do double duty as an extra battery pack. This kickstarter campaign plans to add a storage and charging solution for your AirPods as well. The Power1 iPhone Case ($99) has a 3000 mAh battery for an additional 34 hours of talk time (for iPhone X/XS) or up to 30 AirPod charges. Pretty clever.
Power1 constantly monitors your devices and provides power where and when needed. Power1’s priority charging feature ensures your iPhone and AirPods are always the first to get power. When recharging Power1, your iPhone and AirPods will simultaneously charge first. When your iPhone is full, Power1’s supplemental battery will begin to charge.