Abstract: An improved high energy-density battery for producing continuous low-voltage electrical energy is powered by direct conversion of the kinetic energy of charged particles to electrical potentials. An improved battery comprises at least one primary energy source and a plurality of cells, each cell comprising a secondary electron emitter plate spaced apart from a collector plate. Cells are configured to maximize the number of relatively low-energy secondary electrons from the emitter plates which reaches and is retained by collector plates. Heat production is minimized during efficient energy conversion of the relatively high-energy of primary charged particles to the lower energy but relatively high current capacity of large numbers of secondary electrons.