https://techcrunch.com/2020/08/25/self-charging-thousand-year-battery-startup-ndb-aces-key-tests-and-lands-first-beta-customers/

Pleasanton-based green energy startup NDB, Inc. has reached a key milestone today with the completion of two proof of concept tests of its nano diamond battery (NDB). One of these tests took place at the Lawrence Livermore National Laboratory, and the other at the Cavendish Laboratory at Cambridge University, and both saw NDB’s battery tech manage a 40 percent charge, which is a big improvement over the 15 percent charge collection efficiency (effectively energy lossiness relative to maximum total possible charge) of standard commercial diamond.

NDB’s innovation is in creating a new, proprietary nano diamond treatment that allow for more efficient extraction of electric charge from the diamond used int eh creation of the battery. Their goal is to ultimately commercialize a version of their battery that can self-charge for up to a maximum lifespan of 28,000 years, created from artificial diamond-encased carbon-14 nuclear waste.