Apparatus for supplying electric power to a naval unit, particularly a submarine unit

An electric power supply unit for a submarine vessel, in particular a torpedo, wherein a fluidtight tubular shell (3) defines an elongated cavity (8) containing one or more electric power supply modules (9), each of which comprises an insulating container (10) housing a plurality of lithium-ion polymer batteries. The shell is provided with a normally-closed valve (12) communicating on one side with the elongated cavity and on the other with the outside of the shell to allow extraction of air from the elongated cavity (8) and subsequent introduction of inert gas into the shell. The gas inert gas penetrates inside the containers (10), which are not fluidtight in order to prevent combustion processes of the substances constituting the batteries. A venting valve (13) may be present on an end wall of the tubular shell.