According to this article, an average smartphone uses 2W when in use. That number will largely be dependent on the screen and SOC, which can be turned off or be placed in a lower power state when the phone isn’t actively being used. (The 5W - 20W figure is for charging a phone.)

With 8 of these cells, you’ll have 800μW, or 0.0008W, and you need 2W. You will need to add a few more batteries… About 19,992 more. If 8 of these batteries are about the same size as a regular smartphone battery, you will need the equivalent of 2,500 smartphone batteries to power just one phone.

Too bad they don’t say how much the new batteries weigh! It would have been fun to see…

If we ballpark it and assume something the size of a regular smartphone battery is 50g (1.7 oz), then our stack of 20,000 of these new batteries could be about 125kg (275 lbs).

I won’t be replacing any of my batteries just yet.