An old krellide power cell
A krellide power cell, or krellide storage cell, was a type of power cell.
It was found as part of an old Vulcan transmitter. The transmitter that Trip Tucker used to reach Enterprise NX-01 when he was captured by the Andorians at the monastery at P'Jem used a krellide power cell. (ENT: "The Andorian Incident")
In 2367, the USS Enterprise-D had to escape a dark matter nebula. Captain Jean-Luc Picard decided to pilot a shuttlepod to help escort it, but lost control. Its krellide power cells were damaged, making manual control difficult to maintain. (TNG: "In Theory")
The prop as part of the food processor
The term "krellide power cell" was devised by Rick Sternbach for the hand phasers seen in Star Trek: The Next Generation. It was also his nod to the ancient Krell civilization in the 1950 science fiction film Forbidden Planet. The prop depicting this power cell was later re-used as part of the Vulcan food processor in the fourth season episode "Home". According to Mike and Denise Okuda, this technology was developed by the Vulcans and adapted by Starfleet. ("The Andorian Incident", text commentary, ENT Season 1 DVD special feature; Star Trek Encyclopedia (4th ed., vol. 1, p. 444))