Nitecore offers a variety of powerful & lightweight powerbanks.  These are some of our recommendations for ultralight backpacking. 

Summit 10000
Weight: 6.07 oz
Capacity: 10,000mAh 3.85V (38.5 Wh)
Input: USB-C: 5V=2.4A / 9V=2A
Output: USB-C: 5V=3A / 9V=2.22A / 12V=1.68A

NB10000 Gen 4
Weight: 5 oz
Capacity: 10,000mAh 3.9V (39 Wh)
Input: USB-C: 5V=3A / 9V=2.22A
Output: USB-C: 5V=3A / 9V=2.22A / 12V=1.87A

NB Air 5000
Weight: 3.14 oz
Capacity: 5000mAh 3.88V (19.4Wh)
Input: USB-C: 5V=2.4A / 9V=2A
Output: USB-C: 5V=2.4A / 9V=2A / 12V=1.5A