The present invention relates to the use of SVO classified to a particle size of about 25null to about 75null as a cathode active material in a lithium electrochemical cell. The cathode electrode is fabricated into an electrode assembly by overlaying it with an anode electrode and an intermediate separator. The reduced particle size of the SVO material means that a separator of reduced thickness is used, which provides space for more active materials in a casing of a given volume. The electrode assembly is then hermetically sealed in a casing and used as the power source for such devices as implantable medical devices.