BATTERY CELL HAVING A PRISMATIC CONDUCTIVE HOUSING

Abstract

A battery cell, suitable for use in an electric vehicle, includes a prismatic conductive casing having an electrically conductive casing body with a width (W), a height (H) and a thickness (T) and having a generally rectangular cross-section when seen in the thickness direction (z). A stack of layer assemblies is accommodated in the casing body, each layer assembly including a cathode layer, an anode layer and a separator layer there between, the layers extending in a width direction (x) and in a height direction (y) and being of a generally rectangular shape, a stack height extending in the thickness direction (z). The cathode and anode layers each include a cathode tab and an anode tab, respectively, one set of tabs extending in the width direction (x) along a lower part, substantially along the width (W) of the casing and being in conductive contact with a bottom of the casing.

Claims

1. A battery cell comprising: a prismatic conductive casing having an electrically conductive casing body with a width (W), a height (H) and a thickness (T) and having a generally rectangular cross-section when seen in the thickness direction (z), a stack of layer assemblies accommodated in the casing body, each layer assembly comprising a cathode layer, an anode layer and a separator layer there between, the layers extending in a width direction (x) and in a height direction (y) and being of a generally rectangular shape, a stack height extending in the thickness direction (z), the cathode and anode layers each comprising a cathode tab and an anode tab, respectively, one of the cathode tabs and anode tabs extending in the width direction (x) along a lower part of the stack of layer assemblies, substantially along the width (W) of the casing and being in conductive contact with a bottom of the casing, a conductive cover being attached to the casing body and defining a top plane of the battery cell, a first terminal being situated at or near the top plane, conductively connected to the cover, and the other of the cathode tabs and anode tabs extending in the width direction (x) along a section of an upper part of the stack of layer assemblies, and being connected to a conductor, the conductor extending via an opening in the cover to at or near the top plane and connected to the cover via an insulator member, the conductor forming a second terminal associated to the top plane of the cell.

2. The battery cell according to claim 1, the cathode tabs extending along the lower part of the stack of layer assemblies, the first terminal forming a cathode terminal, the anode tabs extending along the upper part of the stack of layer assemblies, the conductor comprising an anode conductor and the second terminal forming an anode terminal.

3. The battery cell according to claim 1, a spacer member being placed between a bottom part of the stack of layer assemblies and the bottom of the casing, the spacer member extending in the width direction (x) along the cathode tabs or the anode tabs.

4. The battery cell according to claim 1, two or more stacks of layer assemblies being placed in the casing, side by side in the thickness direction (z), the anode tabs and/or the cathode tabs being fused together to form a fused tab assembly, a spacer member running alongside each fused tab assembly between a bottom part of the stack of layer assemblies and the bottom of the casing.

5. The battery cell according to claim 1, the second terminal comprising a circumferential wall of isolating material, extending in the height direction (y) away from the cover, through a hole in the cover, the circumferential wall having an inner rim with a contact surface in a plane substantially transverse to the height direction (y), onto which plane superposed cathode tabs or anode tabs are welded in a lap joint.

6. The battery cell according to claim 5, wherein the second terminal comprises a support wall situated parallel to the top plane and having an outer edge that abuts against the casing body and in inner edge, the circumferential wall extending in the height direction (y) from the support wall at the inner edge, the cover being welded to the casing body while pressing down onto the support wall.

7. The battery cell according to claim 5, wherein the second terminal comprises a conductive terminal cap that is welded on top of the superposed cathode tabs or anode tabs.

8. The battery cell according to claim 1, the anode tabs or cathode tabs being welded to a perimeter of an elongate bus bar member of a conductive material.

9. The battery cell according to claim 8, the bus bar member having at a top surface a cylindrical part extending in the height direction (y), the cover comprising a hole in its top surface in which an isolating part is situated with an opening placed around the cylindrical part, placed over the bus bar member and having a peripheral rim that positions a cathode or anode conductor.

10. An electric vehicle comprising at least one battery cell according to claim 1.

11. A method of manufacturing a battery cell with a prismatic conductive casing having width (W), a height (Y) and a thickness (Z) and having a generally rectangular cross-section when seen in the thickness direction (z), comprising: placing a spacer member at a bottom of a casing body, placing a stack of layer assemblies each comprising a cathode layer, an anode layer and a separator layer there between, the stack comprising cathode tabs and anode tabs and being of a generally rectangular shape, in the casing body, such that the layers extend in a width direction (x) and in a height direction (y), a stack height extending in the thickness direction (z), placing one of the anode tabs and the cathode tabs that extend along a lower part of the stack of layer assemblies, substantially along the width (W) of the casing, and alongside the spacer member in conductive contact with the bottom, the other of the anode tabs and cathode tabs being situated along an upper part, welding the tabs at the upper part to a contact member of a terminal, and attaching a conductive cover to the casing body, the cover having an opening through which the contact member projects in the height direction (y), while exerting a compressive force in the height direction (y), clamping the contact member between the cover and the top of the stack of layer assemblies.

12. The method according to claim 11, the contact member comprising a circumferential wall having an inner rim with a contact surface in a plane substantially transverse to the height direction (y), the tabs at the upper part being superposed onto the contact surface and are welded in a lap joint condition by exerting a compressive force on the tabs in the height direction (y).

13. Method according to claim 11, comprising welding of a conducting cap onto the tabs at the upper part by exerting a compressive force in the height direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Embodiments of battery cell will by way of non-limiting example be described in detail with reference to the accompanying drawings. In the drawings:

[0035] FIG. 1 shows a battery pack formed of prismatic battery cells with a rectangular-shaped bottom surface, connected to a front and rear frame part of an electric vehicle,

[0036] FIG. 2 shows a cross-sectional side view of a battery cell according to the disclosure, in the thickness direction,

[0037] FIG. 3 shows a perspective cross-sectional view of a lower part of a battery cell,

[0038] FIG. 4 shows a perspective cross-sectional view of an upper part of a battery cell,

[0039] FIG. 5 shows a cross-sectional view of a part of an anode terminal,

[0040] FIG. 6 shows an embodiment of two stacks of electrode and separator sheet assemblies connected to a bus bar member,

[0041] FIG. 7 shows a cross-sectional view of an upper part of a battery cell, including the embodiment of FIG. 6,

[0042] FIG. 8 shows the stacks of FIG. 6 with the anode terminal connected to an insulating cover member,

[0043] FIG. 9 shows a cross-sectional view of a battery cell 7, including the embodiment of FIG. 6, with the conductive cover in place,

[0044] FIG. 10 shows an exploded view of a sealing ring of the anode terminal, and

[0045] FIG. 11 shows a perspective view the battery cell of FIGS. 7 and 9.

DETAILED DESCRIPTION

[0046] FIG. 1 shows a frame 1 of an electric vehicle, including a front frame structure 2, a rear frame structure 3, including a rear floor, and a structural battery pack 4, forming a bottom structure 5 of the vehicle. The structural battery pack 4 includes longitudinal sill profiles 6, 7 that interconnect the front and rear frame structures 2, 3 and that support a number of rows of interconnected prismatic battery cells 9. The top plate 10 of the battery pack 4 forms the bottom of the cabin of the vehicle.

[0047] FIG. 2 shows a cross-sectional view of a prismatic battery cell 12, for instance an electrochemical Lithium-ion battery cell, with a rectangular cross-section and a rectangular-shaped footprint, having a width W of for instance 286 mm, a height H of 110 mm and a thickness T of 30 mm. The battery cell 12 includes a casing 13 with a conductive casing body 14 and a conductive cover 15, for instance made of aluminum.

[0048] The casing 13 accommodates one or more stacks 16 of layer assemblies, each layer assembly including an anode layer, a cathode layer and a separator (isolation) layer, interposed between the anode and cathode layers. The layer assemblies extend in the x- and y directions in the plane of the drawing, and are stacked in a direction perpendicular to the plane of the drawing. Each stack 16 may include 160 or more layer assemblies in a z-stacked or jelly roll configuration.

[0049] Each stack 16 includes cathode tabs 18 extending along a lower part 19 of the stack. The cathode tabs 18 are in electrically conducting contact with a conductive bottom 20 of the casing 13 and extend along the width W of the casing 13.

[0050] The stack 16 include anode tabs 22 at an upper part 23 of the stack 16, extending along a part of the width W and passing through an aperture in an insulating lower cover member 17, that is placed on the stack 16, below the conductive cover 15. The anode tabs 22 are connected to an anode terminal 24 that is electrically isolated from the cover 15. A cathode terminal 25 is electrically connected to the cover 15.

[0051] Electrons that are absorbed in a region 30 of the stack 16 of layer assemblies, will, as schematically indicated by the arrows, travel from the cathode terminal 25, via the cover 15, along the sidewall 26 and the conductive bottom 20 of the casing to the respective cathode tab 18 and pass from the cathode tab 18 upwards to the region 30.

[0052] FIG. 3 shows two stacks 16, 16′ of electrode and separator layer assemblies that are arranged side by side in the thickness direction z of the casing 13. The cathode tabs 18, 18′ of the layers in each stack 16, 16′ are fused together and are placed substantially transversely onto the conductive bottom 20. Spacer members 32, 33, 34 support the stacks 16, 16′ and are placed on the bottom 20, extending in the width direction x alongside the cathode tabs 18, 18′. The spacer members 32, 33 and 34 can be made of a plastic material.

[0053] FIG. 4 shows a part of the anode terminal 24 having an isolating support wall 38 that is clamped between the top plane 37 of the cover 15 and an upper sides 39, 39′ of the stacks 16, 16′. The cover 15 is laser welded to the side walls 26 of the cell casing, along a weld 40. An inner edge 41 of the support wall 38 abuts against the side wall 26 of the casing 13. At an outer edge 42 of the support wall 41, a circumferential wall 43 extends upwards through a hole in the cover 15. The circumferential wall 43 has a contact surface 44 onto which the anode tabs 22, 22′ are welded in a lap joint in weld areas 45, 45′, which may be formed by ultrasonic welds. At the weld area's 46, 46′, the anode tabs 22, 22′ are bonded together by vibration welding or a similar welding technique to form a fused anode tab for each stack 16, 16′.

[0054] FIG. 5 shows a protective terminal cap 48 of conductive material being placed within the upper part of circumferential wall 43 and welded onto the anode tabs 22 in the weld area 45 to complete the anode terminal 24.

[0055] FIG. 6 shows an embodiment in which anode tabs 51, 51′ of two stacks 50, 50′ of electrode and separator layer assemblies are welded to the perimeter of an elongate bus bar 52. The bus bar 52 may be formed of aluminum or copper and has a cylindrical stub 53 that is received in a tight fit in a cover member 55, that forms an insulator, as shown in FIGS. 7 and 9. The stub 53 is welded to an anode terminal 56.

[0056] FIG. 7 shows a cross-sectional view of the tabs 51, 51′ extending in the height direction and being welded to the longitudinal sides of the busbar 52. The busbar 52 is conductively connected to the anode terminal 56, that is received in the electrically isolating cover member 55. Conducting cover 59 is welded to the side walls 58 and seals the battery cell.

[0057] FIG. 8 shows a perspective view of the cover member 55 and the anode terminal 56, with the cover 59 removed.

[0058] In FIG. 9 it can be seen that the insulating cover member 55 is clamped between the conducting cover 59 of the housing, that is welded onto the cell casing side walls 58. The exploded view of FIG. 10 shows a sealing ring 60 that is placed around the stub 53 and provides a tight seal between the anode terminal 56 and the isolation cover member 55, preventing moisture or contamination from entering the battery cell.

[0059] FIG. 11 shows the prismatic battery cell with a rectangular-shaped footprint, with the conductive cover 59 welded to the casing body 61, a cathode terminal 62 embedded in the cover 59 and the anode terminal 56 conductively connected to the anode tabs via the cylindrical stub 53.