NOVELTY - An electrochemical cell comprises: (i) a cell enclosure defining an internal volume and including a cover forming an outer face, inner face and a fillport through hole; (ii) fill tube formed separate from the cell enclosure and defining leading and trailing sections and a passageway, the leading section being secured within the fillport through hole; (iii) ball; (iv) closing button; (v) anode and cathode components; and (vi) electrolyte.    USE - For powering implantable medical devices.    ADVANTAGE - The electrochemical cell has a low profile fillport sealing design. By configuring the fill tube such that the leading section is secured within the fillport through hole, an overall extension of the fill tube relative to the internal volume is greatly reduced, thus maximizing a volumetric efficiency.    DETAILED DESCRIPTION - An electrochemical cell comprises:    (a) a cell enclosure (14) defining an internal volume (30) and including a cover (34) forming an outer face, inner face and a fillport through hole (40);    (b) fill tube formed separate from the cell enclosure and defining leading and trailing sections and a passageway, the leading section being secured within the fillport through hole;    (c) ball sealingly secured within the passageway;    (d) closing button formed separate from the case enclosure and sealingly secured within the fillport through hole adjacent the leading section of the fill tube;    (e) anode (18) and cathode (20) components disposed within the internal volume; and    (f) electrolyte (16) contained within the enclosed region and electrically associating the anode and cathode components.    An INDEPENDENT CLAIM is also included for a method of forming a electrochemical cell including an anode and a cathode, comprising:    (a) providing a case defining an upper opening;    (b) providing a cover defining outer and inner faces and fillport through hole;    (c) forming a fill tube apart from the cover and defining leading and trailing sections and a passageway;    (d) securing the leading section of the fill tube within the fillport through hole such that the passageway is in fluid communication with the fillport through hole;    (e) sealing the cover to the case at the upper opening, the housing and the cover combining to define an internal volume;    (f) dispensing an electrolyte into the internal volume via the fill tube passageway;    (g) press-fitting a ball into the passageway of the fill tube to form a secondary seal;    (h) placing a closing button into the fillport through hole downstream of the fill tube; and    (i) securing the closing button to the cover to form a primary seal.    DESCRIPTION OF DRAWING(S) - The figure is a cross-sectional, elevational view of an electrochemical cell including a fillport sealing assembly.    Cell enclosure (14)    Electrolyte (16)    Anode (18)    Cathode (20)    Internal volume (30)    Cover (34)    Fillport through hole (40)