Miniature lithium electrochemical cell with grooved rod-shaped cathode current collector

1 . An electrochemical cell, comprising:

a) a casing, comprising:

i) a casing tube extending from a base wall to an upper annular edge, the casing tube having an outer surface spaced from an inner annular surface; and

ii) a glass-to-metal seal (GTMS) comprising an insulator glass contacting a terminal pin centered inside a ferrule, wherein the ferrule is secured to the upper annular edge of the casing tube; and

b) an electrode assembly housed inside the casing, the electrode assembly comprising:

i) an anode active material contacted to the inner annular surface of the casing tube, wherein the anode active material has a tube shape forming a lumen;

ii) a cathode current collector comprising a rod having a cylindrically-shaped outer surface extending along a longitudinal axis, wherein at least one helical groove recessed into the cylindrically-shaped outer surface of the rod turns around the longitudinal axis at a constant distance while moving parallel to the longitudinal axis, and wherein the current collector is devoid of any feature extending radially outwardly beyond the cylindrically-shaped outer surface of the rod;

iii) a cathode comprising a cathode active material in direct physical contact with the cathode current collector, wherein the cathode has a cylindrical shape and resides in the lumen of the tube-shaped anode active materials and

iv) a separator segregating the anode active material from directed physical contact with the cathode active material; and

c) an electrolyte in the casing activating the electrode assembly,

d) wherein the casing tube contacting the anode active material serves as an anode terminal, and wherein the cathode current collector contacting the cathode active material and being connected to the terminal pin electrically isolated from the casing tube by the GIMS serves as the cathode terminal for the cell.

2 . The electrochemical cell of claim 1 , wherein the at least one helical groove is a narrow channel having the shape in cross-section of a segment of a circle that turns around the longitudinal axis of the at a constant distance while moving parallel to the longitudinal axis of the rod.

3 . The electrochemical cell of claim 1 , wherein two crisscrossing helical grooves recessed into the cylindrically-shaped outer surface of the rod turn around the longitudinal axis in opposed clockwise and counterclockwise directions at a constant distance while moving parallel to the longitudinal axis of the rod.

4 . The electrochemical cell of claim 1 , wherein the rod has a longitudinally aligned, co-axial counter bore, and wherein a proximal end of the terminal pin is received in the counter bore.

5 . The electrochemical cell of claim 4 , wherein a portion of the outer surface of the rod adjacent to the terminal pin is uncontacted by cathode active material.

6 . The electrochemical cell of claim 1 , wherein the anode active material is lithium, and the cathode active material is fluorinated carbon (CF x ).

7 . The electrochemical cell of claim 1 having a total volume that is less than 0.5 cc.

8 . An electrochemical cell, comprising:

a casing, comprising:

i) a casing tube extending from a base wall to an upper annular edge, the casing tube having an outer surface spaced from an inner annular surface; and

ii) a glass-to-metal seal (GTMS) comprising an insulator glass contacting a terminal pin centered inside a ferrule, wherein the ferrule is secured to the upper annular edge of the casing tube; and

b) an electrode assembly housed inside the casing, the electrode assembly comprising:

i) lithium directly contacting the inner annular surface of the casing tube, wherein the lithium has a tube shape forming a lumen;

ii) a cathode current collector comprising a rod having a cylindrically-shaped outer surface extending along a longitudinal axis, wherein at least one helical groove recessed into the cylindrically-shaped outer surface of the rod turns around the longitudinal axis at a constant distance while moving parallel to the longitudinal axis, and wherein the current collector is devoid of any feature extending radially outwardly beyond the cylindrically-shaped outer surface of the rod;

iii) a cathode comprising fluorinated carbon (CF x ) directly contacting the cathode current collector including the at least one helical groove, wherein the cathode has a cylindrical shape and resides in the lumen of the tube-shaped lithium; and

iv) a separator segregating the tube-shaped lithium from directed physical contact with the cathode; and

c) an electrolyte in the casing activating the electrode assembly,

d) wherein the casing tube contacting the lithium serves as an anode terminal, and wherein the cathode current collector contacting the CF x , and being connected to the terminal pin electrically isolated from the casing tube by the GIMS serves as the cathode terminal for the cell.

9 . The electrochemical cell of claim 8 , wherein the at least one helical groove is a narrow channel having the shape in cross-section of a segment of a circle that turns around the longitudinal axis of the rod at a constant distance while moving parallel to the longitudinal axis of the rod.

10 . The electrochemical cell of claim 8 , wherein two crisscrossing helical grooves recessed into the cylindrically-shaped outer surface of the rod turn around the longitudinal axis in opposed clockwise and counterclockwise directions at a constant distance while moving parallel to the longitudinal axis of the rod.

11 . The electrochemical cell of claim 8 , wherein the rod has a longitudinally aligned, co-axial counter bore, and wherein a proximal end of the terminal pin is received in the counter bore.