Abstract: An implantable medical device comprising a housing, a capacitor assembly, an electronics module and an energy source, such as a battery. The capacitor assembly is disposed within the housing. The electronics module is electrically connected to the capacitor assembly and similarly disposed within the housing. The capacitor assembly comprising a case, an electrode stack and an insulative liner between the case and the electrode stack. The capacitor assembly electrode stack comprising a plurality of electrode subassemblies each having a plurality of anode plates and a plurality of cathode plates with a separation layer between anode and cathode plates. The liner also maintains alignment and immobilizes the electrode stack within the capacitor assembly. Finally, the energy source is electrically connected to the electronics module. With this configuration, an overall shape and size of the implantable medical device is optimized.