Lead dioxide batteries. Electrolyte: fluoroboric acid
Electric batteries - Activatable batteries

In some battery applications, the user is looking for a long storage life (over a decade, for example), a very small volume (a few tens to a hundred cubic centimeters), a short activation time (several tens of milliseconds to a second), low cost and can make do with a short discharge time (a few seconds to a minute or a little more). It is possible to use the lead-lead dioxide couple featuring an electrolyte consisting of fluoroboric acid (HBF ₄). Given the size of the battery, the inactive parts of the battery become predominant, and mass energies are low: on the order of one watt-hour per kilogram of battery.

Typical applications for these batteries are proximity fuses and intelligent artillery projectiles, whose shock at the start of the shot and rapid rotation...