Battery cell

Abstract

A battery cell 102 comprises first and second electrode stacks 104,106 each having at least two pairs of electrode connectors comprising a positive electrode connector portion 104a,106a and a negative electrode connector portion 104b,106b and a terminal structure 108 at least partly disposed between the first and second electrode stacks. The terminal structure comprises first and second terminals 110,114 having at least a pair of first openings 112 and a pair of second openings 116, and an electrical insulator 118 between the first and second terminals. One electrode connector portion 104b of the first electrode stack 104 is connected to the first terminal 110 and the other electrode connector portion 104a of the first electrode stack is connected to the second terminal 114 through one of the pair of first openings 112. One electrode connector portion 106a of the second electrode stack 106 is connected to the second terminal 114 and the other electrode connector portion 106b of the second electrode stack is connected to the first terminal 110 through one of the pair of second openings 116. By providing multiple pairs of connector portions, current flows along a shorter path, leading to reduced resistance and heat generation.

Description

TECHNICAL FIELD The present disclosure relates to a battery cell. Aspects of the invention relate to a battery cell, to a battery cell stack, and to a vehicle. BACKGROUND It is known to provide battery cells, for example pouch and prismatic battery cells, having internal electrodes that are terminated together within the cell and then presented to the outside ofthe cell in the form of dedicated terminal pads or tabs. The terminal pads or tabs of battery cells are connected together in series or parallel to form a battery. Resistance along current flow paths in batteries may give rise to heat. It is an aim ofthe present invention to address one or more ofthe disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments ofthe invention provide a battery cell, a battery cell stack, and a vehicle as claimed in the appended claims. According to an aspect ofthe present invention there is provided a battery cell comprising: a first electrode stack having at least two pairs of electrode connector portions, each pair of electrode connector portions comprising a positive electrode connector portion and a negative electrode connector portion; a second electrode stack having at least two pairs of electrode connector portions, each pair of electrode connector portions comprising a positive electrode connector portion and a negative electrode connector portion; and a terminal structure at least partly disposed between each ofthe first electrode stack and the second electrode stack; wherein the terminal structure comprises: a first terminal; a second terminal; and an electrical insulator disposed between each ofthe first terminal and the second terminal; wherein one electrode connector portion of each of the at least two pairs of electrode connector portions of the first electrode stack is connected to the first terminal and the other electrode connector portion of each ofthe at least two pairs of electrode connector portions ofthe first electrode stack is connected to the second terminal; and wherein one electrode connector portion of each of the at least two pairs of electrode connector portions of the second electrode stack is connected to the second terminal and the other electrode connector portion of each ofthe at least two pairs of electrode connector portions ofthe second electrode stack is connected to the first terminal. According to another aspect ofthe present invention there is provided a battery cell comprising: a first electrode stack having at least two pairs of electrode connector portions, each pair of electrode connector portions comprising a positive electrode connector portion and a negative electrode connector portion; a second electrode stack having at least two pairs of electrode connector portions, each pair of electrode connector portions comprising a positive electrode connector portion and a negative electrode connector portion; and a terminal structure at least partly disposed between each ofthe first electrode stack and the second electrode stack; wherein the terminal structure comprises: a first terminal having at least a pair of first openings; a second terminal having at least a pair of second openings; and an electrical insulator disposed between each ofthe first terminal and the second terminal; wherein one electrode connector portion of each of the at least two pairs of electrode connector portions of the first electrode stack is connected to the first terminal and the other electrode connector portion of each ofthe at least two pairs of electrode connector portions of the first electrode stack is connected to the second terminal through one ofthe pair of first openings; and wherein one electrode connector portion of each of the at least two pairs of electrode connector portions of the second electrode stack is connected to the second terminal and the other electrode connector portion of each ofthe at least two pairs of electrode connector portions ofthe second electrode stack is connected to the first terminal through one ofthe pair of second openings. By providing multiple pairs of positive electrode connector portions and negative electrode connector portions in the first and second electrode stacks, current may flow along a shorter path than it would in an electrode stacks having a single positive electrode connector portion and a single. Consequently, less resistance may be encountered and less heat may be produced. The battery cell may comprise a first end and a second end opposite the first end; wherein one first opening ofthe pair of first openings is disposed at the first end, and another first opening ofthe pair of first openings is disposed at the second end; and / or wherein one second opening ofthe pair of second openings is disposed at the first end, and another second opening ofthe pair of second openings is disposed at the second end. Such an arrangement defines a particularly short yet satisfactory current path, thereby mitigating against the generation of excessive heat. In certain embodiments, one positive electrode connector portion ofthe first electrode stack may be aligned with another positive electrode connector portion ofthe first electrode stack along an axis that is parallel to a longitudinal axis ofthe first electrode stack. Such an arrangement defines a particularly short yet satisfactory current path through the first electrode stack, thereby mitigating against the generation of excessive heat. In certain embodiments, one positive electrode connector portion ofthe first electrode stack may be aligned with one negative electrode connector portion of the first electrode stack along an axis that is parallel to a longitudinal axis ofthe first electrode stack. Such an arrangement defines an alternative short yet satisfactory current path through the first electrode stack, thereby mitigating against the generation of excessive heat. In certain embodiments, one positive electrode connector portion ofthe second electrode stack may be aligned with another positive electrode connector portion ofthe second electrode stack along an axis that is parallel to a longitudinal axis ofthe second electrode stack. Such an arrangement defines a particularly short yet satisfactory current path through the second electrode stack, thereby mitigating against the generation of excessive heat. In certain embodiments, one positive electrode connector portion of the second electrode stack is aligned with one negative electrode connector portion of the second electrode stack along an axis that is parallel to a longitudinal axis of the second electrode stack. Such an arrangement defines an alternative short yet satisfactory current path through the second electrode stack, thereby mitigating against the generation of excessive heat. In certain embodiments, the first terminal is one of a positive terminal or a negative terminal; and the second terminal is the other of a positive terminal or a negative terminal. In this manner, the battery cell comprises both positive and negative terminals. In certain embodiments, the first terminal comprises a first terminal planar body and a first terminal outer frame extending around an outer periphery of the first terminal planar body. The first terminal outer frame may form part of a battery cell housing of the battery cell, such that the first terminal may have an electrical and a structural function. In certain embodiments, the second terminal comprises a second terminal planar body and a second terminal outer frame extending around an outer periphery of the second terminal planar body. The second terminal outer frame may form part of a battery cell housing of the battery cell, such that the second terminal may have an electrical and a structural function. In certain embodiments, the battery cell may comprise a first cover sealed to the first terminal to define a sealed volume that contains the first electrode stack and an electrolyte. The first cover may securely contain the electrolyte in the sealed volume. In certain embodiments, the battery cell may comprise a second cover sealed to the second terminal to define a sealed volume that contains the second electrode stack and an electrolyte. The second cover may securely contain the electrolyte in the sealed volume. In certain embodiments, the battery cell may comprise a battery cell frame that extends around a periphery of the battery cell. The battery cell frame may provide structural rigidity to the battery cell and / or may form part of a battery cell housing of the battery cell. According to another aspect of the invention there is provided a battery cell stack comprising a plurality of battery cells each as described above, wherein the plurality of battery cells are stacked on one another. According to another aspect of the invention there is provided a vehicle comprising a battery cell as described above or a battery cell stack as described above. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in anyway and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIG. 1 shows a cross-sectional view of a first end of a battery cell in accordance with an embodiment of the present invention; FIG. 2 shows a cross-sectional view of a second end of the battery cell of FIG. 1; FIG. 3 shows a perspective view of an electrode stack in accordance with an embodiment of the present invention; FIG. 4 shows a perspective view of the battery cell of FIG. 1 and FIG. 2; FIG. 5 shows a schematic view of a battery cell and the flow of current therein in accordance with an embodiment of the present invention; FIG. 6 shows a schematic view of a battery cell and the flow of current therein in accordance with another embodiment of the present invention; FIG. 7 shows a battery cell stack in accordance with an embodiment of the present invention; FIG. 8 shows an exploded view of the battery cell stack of FIG. 7; and FIG. 9 shows a vehicle in accordance with an embodiment of the present invention. DETAILED DESCRIPTION FIG. 1 shows a partial cross-sectional view of a battery cell 102. In particular, a first end 102a of the battery cell 102 is shown in FIG. 1 and a second end 102b of the battery cell 102 that is opposite to the first end 102a is shown in the partial cross-sectional view of FIG. 2. The battery cell 102 comprises a first electrode stack 104 and a second electrode stack 106. As the name suggests, each electrode stack includes a stack of individual electrodes arranged on top of one another. The electrodes include a plurality of positive electrodes (i.e. anodes) and a plurality of negative electrodes (i.e. cathodes) and the stack is arranged such that the positive and negative electrodes are alternately arranged (i.e. with the exception of electrodes at the extremes of the stack, each positive electrode is disposed between two adjacent negative electrodes, and each negative electrode is disposed between two adjacent positive electrodes). Typically, a porous spacer layer is provided between adjacent ones of the individual electrodes, wherein the porous spacer layer physically separates the adjacent electrodes but permits the passage of ions between the adjacent electrodes during charging or discharging of the battery cell 102. The first electrode stack. 104 has a pair of positive electrode connector portions 104a and a pair of negative electrode connector portions 104b. Similarly, the second electrode stack 106 has a pair of positive electrode connector portions 106a and a pair of negative electrode connector portions 106b. In each instance, the positive electrode connector portions of each electrode stack are electrically connected to the positive electrodes (and each other) of the respective electrode stack, and the negative electrode connector portions of each electrode stack are electrically connected to the negative electrodes (and each other) of the respective electrode stack. In FIG. 1 only one positive electrode connector portion 104a of the first electrode stack 104 and only one positive electrode connector portion 106a of the second electrode stack 106 are shown due to the orientation of the cross-section. Similarly, in FIG. 2 only one negative electrode connector portion 104b of the first electrode stack 104 and only one negative electrode connector portion 106b of the second electrode stack 106 are shown due to the orientation of the cross-section. The battery cell 102 comprises a terminal structure 108, part of which is disposed between the first electrode stack 104 and the second electrode stack 106. The terminal structure 108 includes a first terminal 110 and a second terminal 114 (which may each be referred to as a “can”). The first terminal 110 is stacked on the second terminal 114 and has a pair of first openings 112 (only one of which is visible in FIG. 1 due to the orientation of the cross-section). Similarly, the second terminal 114 has a pair of second openings 116 (only one of which is visible in FIG. 2 due to the orientation of the cross-section). In certain embodiments, the first terminal 110 is a metallic structure including aluminium or a similarly conductive metal or metal alloy which, for example, may be press-formed or die-cast. The first terminal 110 has a first terminal planar body 128. The first terminal 110 also has an outer rim or first terminal outer frame 130 which extends around the periphery of the first terminal planar body 128. Similarly, the second terminal 114 may be a metallic structure including aluminium or a similarly conductive metal or metal alloy which, for example, may be press-formed or die-cast. The second terminal 114 has a second terminal planar body 132. The second terminal 114 also has an outer rim or second terminal outer frame 134 which extends around the periphery of the second terminal planar body 132. The battery cell 102 comprises a first cover 120, a second cover 122 and a battery cell frame 124 that extends around a periphery of the battery cell 102. A battery cell housing 126 of the battery cell 102 comprises the first cover 120, the second cover 122, the battery cell frame 124, the first terminal outer frame 130 and the second terminal outer frame 134. The first cover 120 seals to the first terminal 110 to define a sealed volume that contains the first electrode stack 104 and an electrolyte. Similarly, the second cover 122 seals to the second terminal 114 to define a sealed volume that contains the second electrode stack 106 and an electrolyte. In the non-limiting embodiments shown in the figures, the second terminal outer frame 134 has a u-shaped portion configured to receive part of the battery cell frame 124. Such an arrangement may improve the stackabihty of the second terminal 114, the battery cell frame 124 and the 110. In other embodiments, the second terminal outer frame 134 may have other forms. At the first end 102a (as shown in FIG. 1), one of the positive electrode connector portions 104a of the first electrode stack 104 is electrically connected to the second terminal 114 through one of the first openings 112. On an opposing side of the second terminal 114, one of the positive electrode connector portions 106a of the second electrode stack 106 is electrically connected to the second terminal 114. Also at the first end 102a (but out of plane from the view shown in FIG. 1), one of the negative electrode connector portions 104b of the first electrode stack 104 is electrically connected to the first terminal 110 and, on an opposing side of the first terminal 110 one of the negative electrode connector portions 106b of the second electrode stack 106 is electrically connected to the first terminal 110 through one of the second openings 116. Similarly, at the second end 102b (as shown in FIG. 2), one of the negative electrode connector portions 104b of the first electrode stack 104 is electrically connected to the first terminal 110 and, on an opposing side of the first terminal 110 one of the negative electrode connector portions 106b of the second electrode stack 106 is electrically connected to the first terminal 110 through one of the second openings 116. In such embodiments, the first terminal 110 is a positive terminal of the battery cell 102 and the second terminal 114 is a negative terminal of the battery cell 102. Also at the second end 102b (but out of plane from the view shown in FIG. 2), one of the positive electrode connector portions 104a of the first electrode stack 104 is electrically connected to the second terminal 114 through one of the first openings 112. On an opposing side of the second terminal 114, one of the positive electrode connector portions 106a of the second electrode stack 106 is electrically connected to the second terminal 114. An electrical insulator 118 is disposed between the first terminal 110 and the second terminal 114 so that they are electrically isolated from one another. In certain embodiments, the electrical insulator 118 may comprise a polymeric or plastic material such as polyamide 6 (also known as PA6 or nylon 6) or a non-conductive ceramic material. FIG. 3 shows a perspective view of the first electrode stack 104 in which it can be seen the first end 102a includes one positive electrode connector portion 104a and one negative electrode connector portion 104b. As described above, whilst not visible in FIG. 3, the second end 102b also includes one positive electrode connector portion 104a and one negative electrode connector portion 104b. FIG. 4 shows a perspective view of the battery cell 102 with the first cover 120 removed. In FIG. 4 it can be seen that the first electrode stack 104 has one positive electrode connector portion 104a and one negative electrode connector portion 104b at the first end 102a and one positive electrode connector portion 104a and one negative electrode connector portion 104b at the second end 102b. In the manner described above, each of the positive electrode connector portions 104a is electrically connected to the second terminal 114 through one of the first openings 112 whilst each of the negative electrode connector portions 104b is electrically connected to the first terminal 110. In the non-limiting embodiment shown in FIG. 4, the pair of positive electrode connector portions 104a of the first electrode stack 104 are aligned with one another along an axis that is parallel to a longitudinal axis 504 of the first electrode stack 104 . Consequently, each first opening 112 is disposed at an opposite end of the battery cell 102 relative to the other and the pair of first openings 112 are aligned with one another along an axis that is parallel to the longitudinal axis 504. Similarly, the pair of negative electrode connector portions 104b are aligned with one another along an axis that is parallel to the longitudinal axis 504. Whilst not visible in FIG. 4, in the same embodiment the positive electrode connector portions 106a of the second electrode stack 106 will be aligned with one another along an axis that is parallel to a longitudinal axis of the second electrode stack 106 (which will also be parallel to the longitudinal axis 504), and the negative electrode connector portions 106b of the second electrode stack 106 will be aligned with one another along an axis that is parallel to the longitudinal axis of the second electrode stack 106. Consequently (although, again, not visible in FIG. 4), the pair of second openings 116 will be aligned with one another along an axis that is parallel to the longitudinal axis of the second electrode stack 106 (and disposed at opposite ends of the battery cell 102). FIG. 5 schematically shows the (conventional) current 502 in the first electrode stack 104 from each positive electrode connector portion 104a to each negative electrode connector portion 104b. The current 502 may follow this path (in a forwards or backwards direction) during charging and / or discharging of the battery cell 102. The provision of more than one positive electrode connector portion 104a and more than one negative electrode connector portion 104b permits greater current 502 compared with prior art arrangements. In doing so, less unwanted heating arises due to electrical resistance. In the non-limiting embodiment shown in FIG. 5 (and consistent with the embodiment of FIG. 4), the positive electrode connector portions 104a are aligned with one another along an axis that is parallel to the longitudinal axis 504 of the first electrode stack 104. FIG. 6 schematically shows the (conventional) current 502 in an alternative embodiment of the first electrode stack 104. The current 502 may follow this path (in a forwards or backwards direction) during charging and / or discharging of the battery cell 102. Like the first electrode stack 104 of FIG. 5, the first electrode stack 104 of FIG. 6 has a pair of positive electrode connector portions 104a and a pair of positive electrode connector portion negative electrode connector portions 104b. However, unlike the first electrode stack 104 of FIG. 5, the positive electrode connector portions 104a of the first electrode stack 104 of FIG. 6 are not aligned with one another along an axis that is parallel to the longitudinal axis 504. Similarly, the negative electrode connector portions 104b are not aligned with one another along an axis that is parallel to the longitudinal axis 504. Instead, one positive electrode connector portion 104a is aligned with one negative electrode connector portion 104b along an axis that is parallel to the longitudinal axis 504. By providing multiple pairs of positive electrode connector portions 104a and negative electrode connector portions 104b in the first electrode stack 104, current may flow along a shorter path than it would in an electrode stack having a single positive electrode connector portion 104a and a single 104b. Consequently, less resistance may be encountered and less heat may be produced. FIG. 7 shows a battery cell stack 700 formed by stacking multiple battery cells 102 together. FIG. 8 shows an exploded view of the battery cell stack 700. In the non-limiting embodiment shown in FIG. 7 and FIG. 8, the battery cell stack 700 includes an end plate 702, for example a battery frame or a cooling plate support structure. Providing an end plate 702 at each end of the battery cell stack 700 further improves the structural integrity of the battery cell stack 700 by eliminating cell to cell forces, particularly cell to cell forces generated when a compressive material is provided within a gap defined between the second cover 122 of one battery cell 102 and the first cover 120 of an adjacent battery cell 102. In the battery cell stack 700, the first terminal outer frame 130 of the first terminal 110 of one battery cell 102 is joined to the second terminal outer frame 134 of the second terminal 114 of an adjacent battery cell 102. This arrangement advantageously removes the need to provide separate connectors, for example busbars, to enable connection of the adjacent battery cells 102. Advantageously, this improves the reliability of the battery cell stack 700. The first terminal outer frame 130 on one battery cell 102 may be joined to the second terminal outer frame 134 of an adjacent battery cell 102 by any suitable joining means. The join may be, for example an interference fit, a snap fit, a friction fit or a press fit between the first terminal outer frame 130 on one battery cell 102 and the second terminal outer frame 134 of an adjacent battery cell 102. Alternatively, the join may be provided by welding or brazing or soldering the first terminal outer frame 130 on one battery cell 102 and the second terminal outer frame 134 of an adjacent battery cell 102. In some embodiments, the join may be provided by a combination of an interference fit, a snap fit, a friction fit or a press fit between the first terminal outer frame 130 on one battery cell 102 and the second terminal outer frame 134 of an adjacent battery cell 102 and welding or brazing or soldering the first terminal outer frame 130 on one battery cell 102 and the second terminal outer frame 134 of an adjacent battery cell 102. The metallic first terminal planar bodies 128 and second terminal planar bodies 132 increase the stiffness and further enhance the structural integrity of the battery cell 102 and battery cell stack 700, as well as improving the thermal performance of the battery cell 102 and battery cell stack 700. The above-described sandwich arrangement of the battery cell 102 with the nesting of adjacent components or layers of the battery cell 102 also provides efficient packing of the battery cell volume, thereby improving the performance of the battery cell 102. The sandwich cell construction of the battery cell 102 of certain embodiments of the present invention also removes the need for additional components to ensure electrical and mechanical connection of battery cells 102 within a battery cell stack 700 or a battery comprising the battery cell stack 700. This is advantageous as it reduces the number of parts required, and enables the efficiency use of the volume occupied by a battery, as well as a reduction in the mass of the battery. This is particularly beneficial for automotive applications in which it is desirable to reduce the overall mass of components. 5 FIG. 9 shows a vehicle 900 that comprises the battery cell stack 700 in accordance with an embodiment of the present invention. It will be appreciated that various changes and modifications can be made to the present invention without 10 departing from the scope of the present application.

Claims

1. A battery cell comprising:a first electrode stack having at least two pairs of electrode connector portions, each pair of electrode connector portions comprising a positive electrode connector portion and a negative electrode connector portion;a second electrode stack having at least two pairs of electrode connector portions, each pair of electrode connector portions comprising a positive electrode connector portion and a negative electrode connector portion; anda terminal structure at least partly disposed between each of the first electrode stack and the second electrode stack;wherein the terminal structure comprises:a first terminal having at least a pair of first openings;a second terminal having at least a pair of second openings; andan electrical insulator disposed between each of the first terminal and the second terminal;wherein one electrode connector portion of each of the at least two pairs of electrode connector portions of the first electrode stack is connected to the first terminal and the other electrode connector portion of each of the at least two pairs of electrode connector portions of the first electrode stack is connected to the second terminal through one of the pair of first openings; andwherein one electrode connector portion of each of the at least two pairs of electrode connector portions of the second electrode stack is connected to the second terminal and the other electrode connector portion of each of the at least two pairs of electrode connector portions of the second electrode stack is connected to the first terminal through one of the pair of second openings.

2. The battery cell of claim 1, comprising a first end and a second end opposite the first end;wherein one first opening of the pair of first openings is disposed at the first end, and another first opening of the pair of first openings is disposed at the second end; and / orwherein one second opening of the pair of second openings is disposed at the first end, and another second opening of the pair of second openings is disposed at the second end.

3. The battery cell of claim 1 or 2, wherein one positive electrode connector portion ofthe first electrode stack is aligned with another positive electrode connector portion ofthe first electrode stack along an axis that is parallel to a longitudinal axis ofthe first electrode stack.

4. The battery cell of claim 1 or 2, wherein one positive electrode connector portion ofthe first electrode stack is aligned with one negative electrode connector portion ofthe first electrode stack along an axis that is parallel to a longitudinal axis ofthe first electrode stack.

5. The battery cell of any one of claims 1 to 4, wherein one positive electrode connector portion ofthe second electrode stack is aligned with another positive electrode connector portion of the second electrode stack along an axis that is parallel to a longitudinal axis ofthe second electrode stack.

6. The battery cell of any one of claims 1 to 4, wherein one positive electrode connector portion of the second electrode stack, is aligned with one negative electrode connector portion of the second electrode stack along an axis that is parallel to a longitudinal axis of the second electrode stack.

7. The battery cell of any one of claims 1 to 6, wherein the first terminal is one of a positive terminal or a negative terminal; and the second terminal is the other of a positive terminal or a negative terminal.

8. The battery cell of any one of claims 1 to 7, wherein the first terminal comprises a first terminal planar body and a first terminal outer frame extending around an outer periphery of the first terminal planar body.

9. The battery cell of any one of claims 1 to 8, wherein the second terminal comprises a second terminal planar body and a second terminal outer frame extending around an outer periphery of the second terminal planar body.

10. The battery cell of any one of claims 1 to 9, comprising a first cover sealed to the first terminal to define a sealed volume that contains the first electrode stack and an electrolyte.

11. The battery cell of any one of claims 1 to 10, comprising a second cover sealed to the second terminal to define a sealed volume that contains the second electrode stack and an electrolyte.

12. The battery cell of any one of claims 1 to 11, comprising a battery cell frame that extends around a periphery of the battery cell.

13. A battery cell stack comprising a plurality of battery cells each according to any preceding claim, wherein the plurality of battery cells are stacked on one another.

14. A vehicle comprising a battery cell according to any of claims 1 to 12 ora battery cell stack according to claim 13.

Images