Diamond battery puff piece
Here's a video on the process. A lot of puffing about themselves and their tech, but some good info in there as well. They don't talk about where they are getting all the carbon-14, or how much power it currently generates, but they do seem to believe it has the potential to replace lithium batteries.
And since you brought up atmospheric carbon removal, here's an interesting, and balanced, article about that from the NYT:
The New Climate Gold Rush: Scrubbing Carbon From the Sky