Electrochemical cell with improved internal contact
View Patent ↗An electrochemical battery cell with an electrical lead for electrical contact between one of the cell's electrodes and the side of the cell container. A portion of the lead, disposed between the electrode assembly and the side wall of the container, includes an initially non-planar shape that is in a partially deformed, compressed configuration within the cell to bias the lead against the internal surface of the side wall of the container, thereby applying sufficient force to provide good electrical contact between the electrode and the container. The initially non-planar shape can include one or more V-shaped or arc-shaped grooves, and the grooves can be disposed parallel to a longitudinal axis of the electrode assembly. Also disclosed is a process for making such a cell.
1. An electrochemical cell comprising:
a cylindrical container having an inside diameter, at least one side wall and a bottom wall;
a cylindrical electrode assembly having a negative electrode strip, a positive electrode strip, at least one separator strip disposed between the negative and positive electrodes, said electrode assembly having a bottom and an outside diameter defined by a nonconductive external side surface adjacent to the sidewall of the container;
an electrolyte;
wherein either the negative or the positive electrode is in electrical contact with the container side wall through an electrical lead extending from the electrode assembly, and at least a portion of the lead is disposed between the electrode assembly side surface and the container side wall;
wherein the lead is in physical contact with the container side wall by pressure only;
wherein the portion of the lead between the electrode assembly side surface and the container side wall comprises a groove disposed parallel to a longitudinal axis of the electrode assembly; and
wherein the maximum difference between the container inside diameter and the electrode assembly diameter is defined by one equation selected from the group consisting of:
2
R
·
(
1
-
cos
(
W
/
(
2
R
)
)
)
+
ID
-
ID
2
-
(
2
R
sin
(
W
/
(
2
R
)
)
)
2
2
+
t
,
i
)
wherein W is the width of the lead measured along a surface of the lead, t is the material thickness of the lead, R is the radius of an arc formed between two longitudinal edges of the lead, ID is the inside diameter of the container, and (W/R)≦π; and
(
W
2
)
·
sin
(
180
-
θ
2
)
+
(
ID
-
ID
2
-
(
W
2
/
2
)
·
(
1
-
cos
θ
)
2
)
+
t
,
ii
)
wherein W is the width of the lead measured along a surface of the lead, t is the material thickness of the lead, θ is an angle between 0 and 180 degrees defined by two longitudinal edges of the lead, and ID is the inside diameter of the can.
2. The cell according to claim 1 , wherein the electrode assembly further comprises a strip of electrically insulating material covering at least a portion of the electrode assembly side surface.
3. The cell according to claim 1 , wherein at least part of the groove has a V-shape.
4. The cell according to claim 1 , wherein at least part of the groove has an arc-shaped.
5. The cell according to claim 1 , wherein the portion of the lead between the electrode assembly side surface and the container side wall has edges that do not point inward toward the electrode assembly side surface.
6. The cell according to claim 1 , wherein the electrode strips and separator strips are in a spirally wound configuration.
7. An electrochemical battery cell comprising a housing, an electrode assembly and an electrolyte, wherein:
the electrode assembly comprises a negative electrode strip, a positive electrode strip and at least one separator strip disposed between the negative and positive electrodes;
the housing comprises a container having at least one side wall and a bottom wall;
the electrode assembly has an electrically nonconductive external side surface adjacent to the container side wall and a bottom adjacent to the container bottom wall;
one of the negative and positive electrodes is in electrical contact with the container side wall through an electrical lead extending from the electrode assembly, and at least a portion of the lead is disposed between the electrode assembly side surface and the container side wall;
the lead is in physical contact with the container side wall by pressure only; and
the portion of the lead between the electrode assembly side surface and the container side wall comprises a deformed initially non-planar shape, having a single groove disposed parallel to a longitudinal axis of the electrode assembly and two groove edges, that is biased against an internal surface of the container side wall; and
the maximum difference between the container inside diameter and the electrode assembly diameter is defined by one equation selected from the group consisting of:
2
R
·
(
1
-
cos
(
W
/
(
2
R
)
)
)
+
ID
-
ID
2
-
(
2
R
sin
(
W
/
(
2
R
)
)
)
2
2
+
t
,
i
)
wherein the groove is arc-shaped, W is the width of the lead measured along a surface of the lead, t is the material thickness of the lead, R is the radius of an arc formed between two longitudinal edges of the lead, ID is the inside diameter of the container, and (W/R) ≦π; and
(
W
2
)
·
sin
(
180
-
θ
2
)
+
(
ID
-
ID
2
-
(
W
2
/
2
)
·
(
1
-
cos
θ
)
2
)
+
t
,
ii
)
wherein the groove is V-shaped, W is the width of the lead measured along a surface of the lead, t is the material thickness of the lead, θ is an angle between 0 and 180 degrees defined by two longitudinal edges of the lead, and ID is the inside diameter of the can.
8. The cell according to claim 7 , wherein the electrode assembly further comprises a strip of electrically insulating material covering at least a portion of the electrode assembly side surface.
9. The cell according to claim 7 , wherein a plurality of positive electrode strips, a plurality of negative electrode strips and separator strips are in a stacked configuration.
10. The cell according to claim 7 , wherein the electrode strips and separator strips are in a folded configuration.
11. The cell according to claim 7 , wherein the cell is a prismatic cell.
12. The cell according to claim 7 , wherein the electrode assembly is non-cylindrical.