Method for providing battery array for vehicle battery pack

Abstract

The present disclosure provides a method for providing a battery array for a vehicle battery pack. A method of forming a battery pack from a plurality of battery pouch cells, where each battery pouch cell has a pouch and a pair of conductive connectors extending from a portion of a sealed edge of the pouch, the method comprising: forming a battery array using a set of battery pouch cells selected from the plurality of battery pouch cells; and for each battery pouch cell in the battery array, encapsulating at least the pouch of the battery pouch cell with a polyurethane foam formed using a non-conductive physical foaming agent.

Description

Technical Field

[0001] The present disclosure relates to a method for producing a vehicle battery pack. Background Art

[0002] The vehicle battery pack generally includes a plurality of battery arrays formed by a plurality of battery cells. In some examples, the battery cells may be soft-pack type battery cells having a flexible outer structure.

[0003] Except for the packaging step, the battery manufacturing process of the soft-pack battery cell is similar to most battery processes. Specifically, in one example, the battery manufacturing process may generally include an electrode preparation process, a cell assembly process, and a battery electrochemical activation process. In addition to other steps, the cell assembly process may include an electrode forming step, an electrode stacking step, and a cell stack packaging step. During the electrode stacking step, the anode, separator, and cathode are repeatedly stacked, and the electrical connector (i.e., electrical contact tab) is welded to the electrode collector of the cell stack. To form a soft-pack battery cell, the cell stack is provided in a foil bag during the cell stack packaging step, and the foil bag is then sealed with an electrical connector extending from the sealing edge of the foil bag. Summary of the invention

[0004] In one form, the present disclosure is directed to a method of forming a battery pack from a plurality of battery pouch cells, wherein each battery pouch cell has a pouch and a pair of conductive connectors extending from a portion of a sealed edge of the pouch. The method includes: forming a battery array using a group of battery pouch cells selected from the plurality of battery pouch cells; for each battery pouch cell in the battery array, encapsulating at least the pouch of the battery pouch cell with a polyurethane foam formed using a non-conductive physical foaming agent.

[0005] In one form, the present disclosure is directed to a method of forming a battery pack from a plurality of battery pouch cells, wherein each battery pouch cell has a pouch and a pair of conductive connectors extending from a portion of a sealed edge of the pouch. The method includes: applying an insulating film over at least a portion of the pair of conductive connectors; arranging a group of battery pouch cells selected from the plurality of battery pouch cells into a parallel array to form a battery array; injecting a liquid polyurethane precursor having a blowing agent into the battery array; and curing the liquid polyurethane precursor having the blowing agent to form a structural support member around the battery array.

[0006] In one form, the present disclosure is directed to a method of forming a vehicle battery pack from a plurality of battery pouch cells, wherein each battery pouch cell has a pouch and a pair of conductive connectors extending from a sealed edge of the pouch. The method includes: applying an insulating film over at least a portion of the pair of conductive connectors; arranging a group of battery pouch cells selected from the plurality of battery pouch cells into a parallel array to form a battery array; applying a liquid polyurethane precursor having a non-conductive physical blowing agent to the battery array; and curing the liquid polyurethane precursor having the non-conductive physical blowing agent to form a structural support member around the battery array. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 An electric vehicle having a battery pack according to the present disclosure is shown;

[0008] Figure 2 A battery pack having a battery array according to the present disclosure is shown;

[0009] Figure 3 is a flow chart of an example battery array formation process according to the present disclosure;

[0010] Figure 4A A plurality of battery cells and a battery array selected from the battery cells according to the present disclosure are shown;

[0011] Figure 4B It shows that according to the present disclosure Figure 4A A battery array provided in a molding fixture to receive a liquid polyurethane precursor having a non-conductive physical blowing agent;

[0012] Figure 4C It shows that according to the present disclosure Figure 4B An array of batteries provided in the furnace;

[0013] Figure 4D Shows Figure 4C An array of batteries encapsulated in polyurethane foam;

[0014] Figure 5 is a flow chart of another example battery array formation process according to the present disclosure;

[0015] Fig. 6A A battery cell having an insulating film at a sealing edge of the battery cell according to the present disclosure is shown; and

[0016] Figure 6B Another battery cell according to the present disclosure is shown having an insulating film at the sealing edge of the battery cell. DETAILED DESCRIPTION

[0017] As required, detailed embodiments of the present invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely examples of the present invention that can be implemented in various forms and alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized to show details of specific components. Therefore, the specific structural details and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art to adopt the present invention in various ways.

[0018] refer to Figure 1 and Figure 2 , an electric vehicle (EV) 100 (such as an all-electric vehicle or a hybrid vehicle with an internal combustion engine) receives all or some of its propulsion power from a battery pack 102 (i.e., a traction battery pack). In one form, the battery pack 102 includes, among other components, one or more battery arrays 202, wherein each battery array 202 includes a plurality of battery cells 204. In one form, each battery cell 204 is provided as a battery pouch cell and includes a battery electrode stack 210 (the battery electrode stack includes an anode, a separator, and a cathode), a pouch 212 that houses the battery electrode stack, and a pair of conductive connectors 214 (i.e., tabs) provided as positive and negative terminals of the battery cell 204.

[0019] In one form, the soft pack 212 includes at least one edge portion that is sealed to hold the battery electrode stack 210 therein, and the pair of conductive connectors 214 extend from at least one of the sealed edges of the soft pack 212. Although the pair of conductive connectors 214 are shown as being arranged at the same sealed edge, the conductive connectors 214 may extend from different sealed edges of the soft pack 212. In addition, the shape of the soft pack 212 may be adapted in various suitable ways and should not be limited to the shapes shown in the drawings.

[0020] The battery cells 204 do not have a rigid housing because the soft pack 212 is typically formed of a sealed flexible foil. Therefore, the battery cells 204 are typically arranged in a structural support 216 to protect the battery cells 204 from physical deformation, increase the sealing strength of the soft pack 212, and prevent cold exhaust. In one form, the structural support 216 is formed of polyurethane (PU) foam, which, when blended with a flame retardant, further provides thermal insulation and mitigates heat transfer between cells.

[0021] In one form, to provide a structural support 216 and where the battery cells 204 are arranged to form a battery array 202, a liquid PU precursor is first injected into the battery array 202 around the battery cells 204, and then the liquid PU precursor is expanded and cured into a corresponding solid PU foam to form the structural support 216.

[0022] In some applications, the liquid PU precursor may include isocyanate (30% to 70%), polyol (10% to 30%), flame retardant (10% to 60%), and foaming agent (1% to 10%). Water is usually used as a chemical foaming agent, which generates carbon dioxide gas in situ to produce a foam structure while exothermically curing into solid PU foam. However, in battery array applications, water may increase the conductivity of the liquid PU precursor, which may cause the isolation resistance (IR) in the battery cell array to decrease.

[0023] In one form, the present disclosure provides a battery array forming process to form a battery array having a structural support that reduces or prevents IR drop. Specifically and as described in detail herein, the structural support of the battery array is formed using a non-aqueous and non-conductive foaming agent (physical foaming agent), and / or an insulating film is provided at the conductive portion of the battery cell (such as but not limited to a conductive connector). Therefore, the battery array of the present disclosure can have no IR drop, thereby improving the operation of the battery array.

[0024] refer to Figure 3 , combined with 4A, Figure 4B , Figure 4C and Figure 4D An example battery array formation process 300 of the present disclosure is provided and described. At step 302, a plurality of battery cells 402 are obtained, and a group of battery cells 402 selected from the plurality of battery cells 402 are arranged to form a battery array 404. In one form, the battery cells 402 are provided as battery pouch cells formed using known techniques, wherein each battery pouch cell includes a pouch 406 and a pair of conductive connectors 408 extending from a portion of a sealed edge of the pouch 406. In a non-limiting example, Figure 4A A side view of battery cells 402 arranged in parallel is shown.

[0025] Once arranged, the battery cells 402 for the battery array 404 are encapsulated with a PU foam formed using a physical foaming agent in an encapsulation step 304. Specifically, the encapsulation step 304 may include: injecting a liquid PU precursor having a non-conductive physical foaming agent (NCPBA) (step 304A), which may be a non-aqueous agent, and curing the liquid PU to form a PU foam (step 304B). Once cured to form the PU foam, the PU foam and the battery cells 402 are cooled at step 306 and then removed from the molding jig.

[0026] In a non-limiting example, reference Figure 4B, the battery cell 402 is provided in a molding fixture 410 having a cover 412, the cover being adapted to allow a pair of conductive connectors 408 to extend through the cover 412 via a plurality of openings (not shown). The molding fixture 410 may also be adapted to provide gaps between the battery cells 402. A liquid PU precursor 414 having a non-conductive physical foaming agent is injected into the molding fixture 410 via an inlet 416 of the fixture 410. In one form, the non-conductive physical foaming agent includes, but is not limited to, methyl formate, n-pentane, cyclohexane, chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), low boiling point saturated and unsaturated hydrocarbons, and / or hydrofluoroethers (HFEs).

[0027] In one form, the liquid PU precursor 414 flows between the gaps of the battery cells 402 and flows to cover at least the pouch 406 of the battery cells 402. In some variations, the liquid PU precursor 414 is provided to cover the entire pouch and a portion of the conductive connector extending from the sealed edge of the pouch 406.

[0028] refer to Figure 4C In the embodiment, once the liquid PU precursor is provided, the molding jig 410 having the battery array 404 and the liquid PU precursor 414 is placed in an oven 430 to cure the liquid PU 414, thereby forming a PU foam. Figure 4D Once cooled, the battery array 404 with the PU foam 440 is removed from the fixture 410. The PU foam 440 formed with a non-conductive physical foaming agent forms a support structure for the battery array 404 without reducing the IR of the battery array.

[0029] The accompanying drawings show an example arrangement of battery cells 402 and a forming jig 410. It should be readily appreciated that the battery cells 402 may be arranged in a variety of suitable ways and other types of forming jigs may be used. In addition, the number of battery cells 402 used in the battery array 404 is not limited to six (6) and may be two (2) or more battery cells 402.

[0030] In another form, in addition to or in lieu of using a non-conductive physical foaming agent, the battery array formation process employs an insulating film applied to at least a portion of the conductive segments of the battery cells 402. More specifically, referring to Figure 5 , provides an example battery array formation process 500, which is similar to Figure 3 The battery array forming process 300 is shown. Similar steps are identified with the same reference numerals, and their descriptions are omitted for brevity.

[0031] In the process 500, before the battery cells 402 are arranged in the battery array 404 at step 302, an insulating film is applied at least at the sealing edge with the pair of conductive connectors 408 at step 502. More specifically, referring to Fig. 6A , the insulating film 600 is applied to cover a portion of the sealing edge 602 from which the conductive connector 408 extends. For example, the insulating film is provided to cover a portion of the soft package 406 and a portion of the conductive connector 408 on both sides of the battery cell 402, thereby covering a portion of the sealing edge 602. In some variations, the insulating film 600 can also be applied to other portions or all of the sealing edge 602, such as Figure 6B In a non-limiting example, the insulating film 600 may be an insulating tape or a thermal lamination film.

[0032] Once placed, process 500 includes Figure 3 Steps 302, 304, and 306 of the present invention are shown in which battery cells 402 are arranged in a battery array 404, encapsulated in PU foam, and then removed. In one form, at step 304A, instead of using liquid PU with a non-conductive physical blowing agent, other liquid PU precursors may be used, such as, but not limited to, liquid PU with a chemical blowing agent.

[0033] Although exemplary embodiments are described above, these embodiments are not intended to describe all possible forms of the present invention. Rather, the words used in the specification are descriptive rather than restrictive terms, and it should be understood that various changes may be made without departing from the spirit and scope of the present invention. In addition, the features of the various embodiments of implementation may be combined to form other embodiments of the present invention.

[0034] According to the present invention, a method for forming a battery pack from a plurality of soft-pack battery cells, each soft-pack battery cell having a soft pack and a pair of conductive connectors extending from a portion of a sealing edge of the soft pack, the method comprising: forming a battery array using a group of soft-pack battery cells selected from the plurality of soft-pack battery cells; and for each soft-pack battery cell in the battery array, encapsulating at least the soft pack of the soft-pack battery cell with a polyurethane foam formed using a non-conductive physical foaming agent.

[0035] In one aspect of the present invention, for each battery soft-pack cell in the battery array, at least the soft pack encapsulating the battery soft-pack cell further includes: applying a liquid polyurethane precursor having the non-conductive physical foaming agent to the battery array; and heating the battery array to cure the liquid polyurethane precursor to form the polyurethane foam.

[0036] In one aspect of the present invention, the non-conductive physical blowing agent comprises at least one of the following: methyl formate, n-pentane, cyclohexane, chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), low boiling point saturated and unsaturated hydrocarbons or hydrofluoroethers (HFEs).

[0037] In one aspect of the invention, the method comprises applying an insulating film at least at the sealing edge with the pair of conductive connectors before encapsulation.

[0038] In one aspect of the present invention, the insulating film is also applied to a portion of the sealing edge that does not have the pair of conductive connectors.

[0039] In one aspect of the present invention, the insulating film is at least one of an insulating tape or a thermal lamination film.

[0040] According to the present invention, a vehicle battery pack includes a plurality of battery arrays formed by the method of the previous embodiment.

[0041] According to the present invention, a method for forming a battery pack from a plurality of battery soft-pack cells, each battery soft-pack cell having a soft pack and a pair of conductive connectors extending from a sealed edge of the soft pack, the method comprising: applying an insulating film on at least a portion of the pair of conductive connectors; arranging a group of battery soft-pack cells selected from the plurality of battery soft-pack cells into a parallel array to form a battery array; injecting a liquid polyurethane precursor having a blowing agent into the battery array; and curing the liquid polyurethane precursor having the blowing agent to form a structural support member around the battery array.

[0042] In one aspect of the present invention, curing the liquid polyurethane precursor further comprises: heating the battery array to cure the liquid polyurethane precursor to form polyurethane foam as the structural support around the battery array.

[0043] In one aspect of the present invention, the blowing agent is a non-conductive physical blowing agent.

[0044] In one aspect of the present invention, the non-conductive physical blowing agent comprises at least one of the following: methyl formate, n-pentane, cyclohexane, chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), low boiling point saturated and unsaturated hydrocarbons or hydrofluoroethers (HFEs).

[0045] In one aspect of the present invention, the blowing agent is a non-aqueous physical blowing agent.

[0046] In one aspect of the present invention, the insulating film is also applied to a portion of the sealing edge that does not have the pair of conductive connectors.

[0047] In one aspect of the present invention, the insulating film is at least one of an insulating tape or a thermal lamination film.

[0048] According to the present invention, a vehicle battery pack includes a plurality of battery arrays formed by the method of the previous embodiment.

[0049] According to the present invention, a method for forming a vehicle battery pack from a plurality of battery soft-pack cells, each battery soft-pack cell having a soft pack and a pair of conductive connectors extending from a sealed edge of the soft pack, the method comprising: applying an insulating film on at least a portion of the pair of conductive connectors; arranging a group of battery soft-pack cells selected from the plurality of battery soft-pack cells into a parallel array to form a battery array; applying a liquid polyurethane precursor having a non-conductive physical blowing agent to the battery array; and curing the liquid polyurethane precursor having the non-conductive physical blowing agent to form a structural support member around the battery array.

[0050] In one aspect of the present invention, curing the liquid polyurethane precursor further comprises: heating the battery array to cure the liquid polyurethane precursor to form polyurethane foam as the structural support around the battery array.

[0051] In one aspect of the present invention, the non-conductive physical blowing agent is selected from: methyl formate, n-pentane, cyclohexane, chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), hydrogenated chlorofluorocarbons (HCFCs), low boiling point saturated and unsaturated hydrocarbons or hydrofluoroethers (HFEs).

[0052] In one aspect of the present invention, the insulating film is also applied to a portion of the sealing edge that does not have the pair of conductive connectors.

[0053] In one aspect of the present invention, the insulating film is at least one of an insulating tape or a thermal lamination film.

Claims

1. A method of forming a battery pack from a plurality of battery soft pack cells, each battery soft pack cell having a soft pack and a pair of conductive connectors extending from a portion of a sealing edge of the soft pack, the method comprising: forming a battery array using a group of battery pouch cells selected from the plurality of battery pouch cells; as well as For each battery pouch cell in the battery array, at least the pouch of the battery pouch cell is encapsulated with a polyurethane foam formed using a non-conductive physical foaming agent.

2. The method of claim 1, wherein for each battery soft pack cell in the battery array, encapsulating at least the soft pack in the battery soft pack cell further comprises: applying a liquid polyurethane precursor having the non-conductive physical blowing agent to the cell array; as well as The battery array is heated to cure the liquid polyurethane precursor to form the polyurethane foam.

3. The method of claim 1, wherein the non-conductive physical blowing agent comprises at least one of the following: methyl formate, n-pentane, cyclohexane, chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), low boiling point saturated and unsaturated hydrocarbons, or hydrofluoroethers (HFEs).

4. The method of claim 1, further comprising applying an insulating film at least at the sealing edge having the pair of conductive connectors prior to encapsulation.

5. The method of claim 4, wherein the insulating film is also applied to a portion of the sealing edge that does not have the pair of conductive connectors. The method of claim 4 , wherein the insulating film is at least one of an insulating tape or a thermal lamination film.

7. A vehicle battery pack, comprising: A plurality of battery arrays are formed by the method according to claim 1.

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