FIELD OF THE INVENTION

[0001] The present invention relates in general to electric vehicle batteries and more specifically to a welded plastic film blanket to provide thermal management for electric vehicle batteries.

BACKGROUND OF THE INVENTION

[0002] Battery packs used with electric vehicles store large amounts of energy in a small space, producing high energy densities. These battery packs are designed to provide high levels of safety and stability, yet situations can arise where a portion of a battery pack experiences a local thermal condition which generates significant heat. When the temperature is great enough and sustained, the local thermal condition can transform into a runaway thermal condition affecting wide areas of the battery pack, and sometimes, the entire battery pack. This runaway thermal condition can begin when the local thermal condition approaches the runaway thermal point, which can be about 200°C.

[0003] Although the art discloses a variety of techniques for cooling the battery pack of an electric vehicle, a need continues to exist for a thermal management system that is capable of maintaining batteries within their desired operating temperature range while minimizing the risks to the vehicle's passengers from runaway thermal conditions.

SUMMARY OF THE INVENTION

[0004] Accordingly, the present invention reduces or eliminates problems inherent in the art by providing a welded plastic film blanket to provide thermal management for electric vehicle batteries. The welded plastic film blanket helps a thermal management system maintain the batteries within their desired operating temperature range thereby minimizing risks to the vehicle’s passenger.

[0005] It is understood that the invention disclosed and described in this specification is not limited to the embodiments summarized in this Summary.

BRIEF DESCRIPTION OF THE FIGURES [0006] The present invention will now be described for purposes of illustration and not limitation in conjunction with the figures, wherein: [0007] FIG. 1 shows one embodiment of the welded plastic film blanket of the invention;

[0008] FIG. 2 illustrates one embodiment of the inventive welded plastic film blanket arranged to cool fuel cells in a vehicle battery;

[0009] FIG. 3 shows one embodiment of the inventive welded plastic film blanket having a molded coolant channels to keep the channels from collapsing.

DETAILED DESCRIPTION OF THE INVENTION [0010] The present invention will now be described for purposes of illustration and not limitation. Except in the operating examples, or where otherwise indicated, all numbers expressing quantities, percentages, and so forth in the specification are to be understood as being modified in all instances by the term “about.”

[0011] Any numerical range recited in this specification is intended to include all sub-ranges of the same numerical precision subsumed within the recited range. For example, a range of “1.0 to 10.0” is intended to include all sub-ranges between (and including) the recited minimum value of 1.0 and the recited maximum value of 10.0, that is, having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4 to 7.6. Any maximum numerical limitation recited in this specification is intended to include all lower numerical limitations subsumed therein and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations subsumed therein. Accordingly, Applicant reserves the right to amend this specification, including the claims, to expressly recite any sub-range subsumed within the ranges expressly recited herein. All such ranges are intended to be inherently described in this specification such that amending to expressly recite any such sub-ranges would comply with the requirements of 35 U.S.C. § 112(a), and 35 U.S.C. § 132(a). The various embodiments disclosed and described in this specification can comprise, consist of, or consist essentially of the features and characteristics as variously described herein.

[0012] Any patent, publication, or other disclosure material identified herein is incorporated by reference into this specification in its entirety unless otherwise indicated, but only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material expressly set forth in this specification. As such, and to the extent necessary, the express disclosure as set forth in this specification supersedes any conflicting material incorporated by reference herein. Any material, or portion thereof, that is said to be incorporated by reference into this specification, but which conflicts with existing definitions, statements, or other disclosure material set forth herein, is only incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material. Applicant reserves the right to amend this specification to expressly recite any subject matter, or portion thereof, incorporated by reference herein.

[0013] Reference throughout this specification to “various non-limiting embodiments,” “certain embodiments,” or the like, means that a particular feature or characteristic may be included in an embodiment. Thus, use of the phrase “in various non-limiting embodiments,” “in certain embodiments,” or the like, in this specification does not necessarily refer to a common embodiment, and may refer to different embodiments. Further, the particular features or characteristics may be combined in any suitable manner in one or more embodiments. Thus, the particular features or characteristics illustrated or described in connection with various or certain embodiments may be combined, in whole or in part, with the features or characteristics of one or more other embodiments without limitation. Such modifications and variations are intended to be included within the scope of the present specification.

[0014] The grammatical articles “a”, “an”, and “the”, as used herein, are intended to include “at least one” or “one or more”, unless otherwise indicated, even if “at least one” or “one or more” is expressly used in certain instances. Thus, these articles are used in this specification to refer to one or more than one (i.e., to “at least one”) of the grammatical objects of the article. By way of example, and without limitation, “a component” means one or more components, and thus, possibly, more than one component is contemplated and may be employed or used in an implementation of the described embodiments. Further, the use of a singular noun includes the plural, and the use of a plural noun includes the singular, unless the context of the usage requires otherwise.

[0015] In a first aspect, the present invention is directed to a thermal management system for use with a battery pack, the battery pack comprising a plurality of cells arranged into at least a first row of cells and a second row of cells, wherein the first row of cells is adjacent to the second row of cells, the system comprising: a welded plastic film blanket interposed between the first and second rows of cells, the blanket comprising; a coolant within a first coolant tube and a second coolant tube, the first coolant tube and the second coolant tube each connected to a plurality of coolant channels in the blanket.

[0016] In a second aspect, the present invention is directed to an electric vehicle including the thermal management system of the preceding paragraph. [0017] In a third aspect, the present invention is directed to a method of managing the temperature of an electric vehicle battery pack with the thermal management system of the preceding two paragraphs.

[0018] As used herein, the terms "battery", "cell", and "battery cell" may be used interchangeably and may refer to any of a variety of different cell types, chemistries and configurations including, but not limited to, lithium ion (e.g., lithium iron phosphate, lithium cobalt oxide, other lithium metal oxides, etc.), lithium ion polymer, nickel metal hydride, nickel cadmium, nickel hydrogen, nickel zinc, silver zinc, or other battery type/configuration.

[0019] As used herein, a collection of battery cells are referred to as a module. The term "battery pack" as used herein refers to a collection of modules, the individual battery cells of which are electrically interconnected to achieve the desired voltage and capacity for a particular application. In various embodiments, the inventive welded plastic film blanket is used to cool the battery pack.

[0020] The term "electric vehicle" as used herein refers to either an all-electric vehicle, also referred to as an EV, a plug-in hybrid vehicle, also referred to as a PHEV, or a hybrid vehicle (HEV), a hybrid vehicle utilizing multiple propulsion sources one of which is an electric drive system.

[0021] In some embodiments, the cells in the illustrated embodiments have a cylindrical form, the invention may be used with other cell designs, shapes, configurations and form-factors, e.g., cylindrical, pouch, and prismatic. Also, the invention is not limited to a battery pack with a specific number of cells, a specific cell interconnect arrangement, or a specific battery pack configuration.

[0022] The plastic for the welded plastic film blanket is chosen from thermoplastic polyurethanes such as TEXIN (also, DUREFLEX and PLATILON thermoplastic polyurethane films) all commercially available from Covestro; thermoplastic elastomers, particularly those with resistance to glycol- water coolants, for example, VERSAFLEX, commercially available from PolyOne or those from Kraton Corp.; polyether block amides such as PEBAX from Arkema; polycarbonate containing blends such as BAYBLEND TP4065 commercially available from Covestro; polytetrafluoroethylenes; polyvinylidene fluorides; and thermoplastic vulcanizates, such as SANTOPRENE, commercially available from ExxonMobil. The plastic films may optionally contain flame retardant additives and/or electrostatic dissipative additives e.g., carbon or carbon nanotubes. [0023] The plastic films may be produced by in various embodiments by extrusion, blown film, flat die, or co-extrusion as known in the art. The films may be radio-frequency welded, laser welded, or heat welded for example, to create the cooling channels within the plastic film blanket. In some embodiments, the plastic film may be molded to form the channels within the blanket to keep the channels from collapsing. In other embodiments, the cooling channel may be produced via profile extrusion. The thickness of the plastic films in various embodiments is from 50 pm to 1 mm, in certain embodiments, from 250 pm to 750 pm, and in selected embodiments 500 pm. In certain embodiments, the plastic film is coated to improve resistance to the coolant.

EXAMPLES

[0024] The non-limiting and non-exhaustive examples that follow are intended to further describe various non-limiting and non-exhaustive embodiments without restricting the scope of the embodiments described in this specification.

[0025] FIG. 1 shows one embodiment of the welded plastic film blanket of the invention. As shown in FIG. 1, first coolant tube 1 is connected to coolant channels 20 within the blanket 4 and acts as an inlet for coolant, such as a glycol-water mixture. The coolant passes through the coolant channels 20 in the blanket before exiting through second coolant tube 2.

[0026] The coolant tubes 1 and 2 may be made of any suitable plastic material and are connected to a circulating pump (not shown) to provide circulation of the coolant within the system. The thermal management system also includes a controller (not shown) for regulating the pump along with a refrigerated reservoir (not shown) for providing a continuous flow of liquid coolant to the pump.

[0027] FIG. 2 illustrates one arrangement of the inventive welded plastic film blanket to cool fuel cells in a vehicle battery with blanket 4, interposed between cylindrical battery cells 3.

[0028] FIG. 3 shows one embodiment of the inventive welded plastic film blanket 4 having molded coolant channels 20 to help keep the channels from collapsing. The molded channel can act as a structural element to maintain the shape of the channel while under fluidized internal pressure.

[0029] This specification has been written with reference to various non- limiting and non- exhaustive embodiments. However, it will be recognized by persons having ordinary skill in the art that various substitutions, modifications, or combinations of any of the disclosed embodiments (or portions thereof) may be made within the scope of this specification. Thus, it is contemplated and understood that this specification supports additional embodiments not expressly set forth herein. Such embodiments may be obtained, for example, by combining, modifying, or reorganizing any of the disclosed steps, components, elements, features, aspects, characteristics, limitations, and the like, of the various non-limiting embodiments described in this specification. In this manner, Applicant reserves the right to amend the claims during prosecution to add features as variously described in this specification, and such amendments comply with the requirements of 35 U.S.C. §112(a), and 35 U.S.C. §132(a).

[0030] Various aspects of the subject matter described herein are set out in the following numbered clauses:

[0031] Clause 1. A thermal management system for use with a battery pack, the battery pack comprising a plurality of cells 3 arranged into at least a first row of cells and a second row of cells, wherein the first row of cells is adjacent to the second row of cells, the system comprising: a plastic film blanket 4 interposed between the first and second rows of cells, the blanket 4 comprising; a coolant within a first coolant tube 1 and a second coolant tube 2, the first coolant tube 1 and the second coolant tube 2 each connected to a plurality of coolant channels 20 in the blanket 4.

[0032] Clause 2. The thermal management system according to Clause 1, wherein the plastic is selected from the group consisting of thermoplastic polyurethanes, thermoplastic elastomers, poly ether block amides, polytetrafluoroethylenes, polyvinylidene fluorides, and thermoplastic vulcanizates, and mixtures of at least two thereof.

[0033] Clause 3. The thermal management system according to Clause 2, wherein the plastic further includes one selected from the group consisting of flame retardant additives, electrostatic dissipative additives, and mixtures thereof.

[0034] Clause 4. The thermal management system according to any one of Clauses 1 to 3, wherein the coolant channels 20 are formed by a process selected from the group consisting of radio frequency welding, laser welding, adhesive bonding, heat welding, and a combination of at least two thereof.

[0035] Clause 5. The thermal management system according to any one of Clauses 1 to 3, wherein the coolant channels 20 are molded into the blanket.

[0036] Clause 6. The thermal management system according to any one of Clauses 1 to 5, wherein the plastic is resistant to glycol-water mixtures. [0037] Clause 7. The thermal management system according to any one of Clauses 1 to 6, wherein the coolant is a glycol-water mixture.

[0038] Clause 8. The thermal management system according to any one of Clauses 1 to 7, wherein the plurality of cells 3 have a shape selected from the group consisting of cylindrical, pouch, and prismatic.

[0039] Clause 9. The thermal management system according to any one of Clauses 1 to 8, wherein the coolant flows into the first coolant tube 1, through the plurality of coolant channels 20 and out of the second coolant tube 2.

[0040] Clause 10. The thermal management system according to any one of Clauses 1 to 9, wherein the first 1 and second 2 coolant tubes are connected to a circulating pump.

[0041] Clause 11. An electric vehicle including a battery pack and the thermal management system according to any one of Clauses 1 to 10.