Implantable medical device having flat electrolytic capacitor with tailored anode layers

An implantable medical device comprising:

• a housing;
• an electronics module disposed within the housing;
• an energy source disposed within the housing and electrically coupled to the electronics module;
• and
• an optimally sized capacitor assembly disposed within the housing and electrically coupled to the electronics module, the capacitor assembly further comprising:
• a sealed capacitor case defining an interior case chamber of pre-existing dimension, the case having a base having a base peripheral edge, a case side wall extending between the base peripheral edge to a side wall opening edge defining a case opening edge, and a cover sealed against the case opening edge to enclose the interior case chamber, whereby the interior case chamber has a case chamber periphery and a case chamber height Hcw;
• and
• an electrode stack assembly optimally sized to be located within the interior case chamber comprising N capacitor layers stacked in registration upon one another and between the case base and the cover having a stack height HN selected to be equal to or less than the case chamber height Hcw by a predetermined tolerance,
• wherein N1 capacitor layers of the N capacitor layers each have a first capacitor layer thickness TCL1 and each further comprise:
• a cathode layer having a cathode layer thickness and a cathode peripheral edge extending toward the case side wall throughout a major portion of said case chamber periphery and having a cathode tab extending toward the case side wall in a minor portion of said case chamber periphery;
• an anode sub-assembly comprising x anode layers each having anode layer thickness tx and an anode layer peripheral edge extending toward the case side wall throughout a major length of said base peripheral edge, whereby each anode sub-assembly has an anode sub-assembly thickness Tx and further comprises an anode tab extending toward the case side wall in a minor portion of said case chamber periphery;
• and
• a plurality of electrolyte bearing separator layers each having a separator peripheral edge extending toward the case side wall, the electrolyte bearing separator layers disposed on each side of the anode sub-assembly and the cathode layer of the capacitor layer,
• whereby the first capacitor layer thickness TCL1 is dependent upon the thickness of the plurality of separator layers, the cathode layer thickness and the anode sub-assembly thickness Tx;
• and
• wherein N2 of the N capacitor layers each have a second capacitor layer thickness TCL2 and each comprise:
• a cathode layer having a cathode layer thickness and a major cathode peripheral edge extending toward, but spaced from, the case side wall a distance D2 throughout a major portion of said case chamber periphery and having a cathode tab extending toward the case side wall in a minor portion of said case chamber periphery;
• an anode sub-assembly comprising y anode layers each having anode layer thickness ty and an anode layer peripheral edge extending toward, but spaced from, the case side wall a distance D1 throughout a major length of said base peripheral edge, whereby each anode sub-assembly has an anode sub-assembly thickness Ty and further comprises an anode tab extending toward the case side wall in a minor portion of said case chamber periphery;
• and
• a plurality of electrolyte bearing separator layers each having a separator peripheral edge extending toward, and abutting the case side wall over a majority of the separator peripheral edge, the electrolyte bearing separator layers disposed on each side of the anode sub-assembly and the cathode layer of the capacitor layer,
• whereby the second capacitor layer thickness TCL2 is dependent upon the thickness of the plurality of separator layers, the cathode layer thickness and the anode sub-assembly thickness Ty;
• wherein the distance D1 is approximately equal to the distance D2;
• and
• whereby the stack height HN is dependent upon N1*TCL1+N2*TCL2.