WO2020074985A1

WO2020074985A1 - Battery cell housings

Info

Publication number: WO2020074985A1
Application number: PCT/IB2019/057815
Authority: WO
Inventors: Fen Zhang; Wei Shan; Franciscus Maria Huijs; Yun ZHENG
Original assignee: Sabic Global Technologies B.V.
Priority date: 2018-10-10
Filing date: 2019-09-17
Publication date: 2020-04-16

Abstract

A battery cell comprising: a housing formed from a polyketone composition comprising 50 to 100 wt% of an aliphatic polyketone derived from carbon monoxide and a C2-6 alpha olefin; and preferably less than 15 wt% of polyamides; wherein the weight percent is based on the total weight of the polyketone composition; an electrolyte enclosed within and in direct physical contact with an inner surface of the housing; an anode and a cathode that are each in contact with the electrolyte; a separator separating the anode from the cathode; and a first terminal and a second terminal electrically coupled to the anode and cathode respectively and extending outwardly from the housing.

Description

BATTERY CELL HOUSINGS

BACKGROUND

[0001] This disclosure relates to battery cell housings, and in particular battery cell housings such as rechargeable lithium ion battery cell housings that are in direct physical contact with electrolyte solvents, and battery cells containing such housings.

[0002] Electric vehicles (EV) use one or more electric motors as their primary source of propulsion. In electric vehicles, electrical energy is stored in rechargeable batteries. A battery for electric vehicles can include a cluster of cells connected together for greater voltage and/or current capacity. Battery cells typically have an electrolyte and a positive and negative electrode (cathode and anode), separated by a thin, porous film known as a separator. Currently most of the housings for battery cells are made of phosphorus-aluminum (P-Al) foil films or other metals. In recent years, there has been a boost in EV market due to technology developments, government incentives, and increased focus on renewable energy. However, the bottleneck that constrained the EV promotion is that EVs typically have shorter driving ranges per charge than conventional vehicles have per tank of gasoline. Therefore, advances in EV battery technology that can make the batteries last longer have become critically important, and batteries having increased energy density with reduced weight are continuously sought.

SUMMARY

[0003] A battery cell comprises a housing comprising a polyketone layer formed from a polyketone composition comprising 50 to 100 wt % of an aliphatic polyketone derived from carbon monoxide and a C_2-6 alpha olefin; and preferably less than 15 wt% of polyamides; wherein the weight percent is based on the total weight of the polyketone composition; an electrolyte enclosed within and in direct physical contact with the polyketone layer; an anode and a cathode that are each in contact with the electrolyte; a separator separating the anode from the cathode; and a first terminal and a second terminal electrically coupled to the anode and cathode respectively and extending outwardly from the housing.

[0004] A battery system comprising a plurality of electrically connected battery cells as described above is also disclosed.

BRIEF DESCRIPTION OF THE DR AWINGS

[0005] The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

[0006] FIG. 1 is a perspective top view of a battery cell housing according to an embodiment of the disclosure;

[0007] FIG. 2 is a side view of a battery cell housing according to another embodiment of the disclosure;

[0008] FIG. 3 is a partially cutaway perspective illustration of a battery cell according to an embodiment of the disclosure;

[0009] FIG. 4 is a scanning electron microscope (SEM) image of a polyketone tensile bar before an immersion test;

[0010] FIG. 5 is a SEM image of the polyketone tensile bar of FIG. 1 after the bar has been immersed in an electrolyte solvent at 60°C for 7 days; and

[0011] FIG. 6 is a SEM image of the polyketone tensile bar of FIG. 1 after the bar has been immersed in an electrolyte solvent at 60°C for 14 days.

DETAILED DESCRIPTION

[0012] The inventors hereof have found that battery cell housings with reduced cost and comparable or improved performance can be readily made from polyketone compositions as disclosed herein. In particular, compared to metals, the polyketone compositions are easier to process. Accordingly, the polyketone battery cell housings can be manufactured with increased productivity and reduced cost. In addition, the polyketone housings are lighter than metal housings and the reduced weight can help battery cells to achieve higher energy density. Furthermore, the polyketone compositions have excellent barrier properties and chemical resistance, and are particularly useful for making battery cell housings that are in direct physical contact with electrolytes.

[0013] The polyketone compositions can comprise 50 to 100 wt%, 50 to 90 wt%, 50 to 80 wt%, 50 to 70 wt%, 50 to 60 wt%, 75 to 100 wt%, 75 to 95 wt%, 75 to 90 wt%, 80 to 100 wt%, 80 to 95 wt%, 80 to 90 wt.%, 90 to 100 wt% or 95 to 100 wt% of an aliphatic polyketone derived from carbon monoxide and one or more C2-6 alpha olefins based on the total weight of the polyketone compositions. Specific examples of the aliphatic polyketone include those derived from carbon monoxide and ethylene (also referred to as“copolymers”) or those derived from carbon monoxide, ethylene, and propylene (also referred to as “terpolymers”). The polyketone copolymers have repeating units of formula (I):

[0014] The polyketone terpolymers can have repeating units of formulas (I) and (P):

where the molar ratio of the repeating units of Formula (II) relative to the repeating units of

Formula (I) can be 0.03 to 0.3.

[0015] The aliphatic polyketone has a melt flow index of greater than 5 grams (g)/l0 minutes (min), greater than 20 g/10 min, or greater than 55 g/10 min as measured at a temperature of 240°C and a load of 2.16 kilograms according to ASTM D1238-13, and a notched Izod impact strength of greater than 90 Joule/meter (J/m) determined according to ASTM D256-10 at 23°C. Aliphatic polyketones are generally known. Examples of commercially available aliphatic polyketones include those sold under the tradename M330A, available from Hyosung Corporation.

[0016] In some embodiments, the polyketone compositions can further optionally include at least one additional polymer, with the proviso that the polymers are selected so as to not significantly adversely affect the desired properties of the compositions. Examples of such additional polymers include one or more of polyolefins (such as polypropylene), polyesters, polyphenylene ether, or poly(phenylene ether).

[0017] Polyolefins may be a polymer of an alpha-olefin such as polyethylene, polypropylene, and polybutylene. The polyolefin may also be a copolymer of two or more olefins. Preferably the polyolefin is polyethylene or polypropylene.

[0018] Polyesters include those derived from an aliphatic, cycloaliphatic, or aromatic diol, or mixtures thereof, containing from 2 to about 10 carbon atoms and an aliphatic, cycloaliphatic, or aromatic dicarboxylic acid, and have repeating units of the following general formula:

wherein n is an integer of from 2 to 6, and R¹ and R² are each independently a divalent C₁-C₂₀ aliphatic radical, a C₂-C₁₂ cycloaliphatic alkyl radical, or a C₆-C₂₄ aromatic radical. [0019] The polyesters can be formed from terephthalic acid and a combination of ethylene glycol and cyclohexadimethanol; preferably formed from terephthalic acid and a combination of ethylene glycol, diethylene glycol and cyclohexadimethanol. Examples of polyesters include at least one of poly(ethylene terephthalate), poly- cyclohexylenedimethylene terephthalate glycol, poly( 1 ,4-cyclohexylenedimethylene 1,4- cyclohexanedicarboxylate), and polyethyelene naphthalate, poly-cyclohexylenedimethylene- terephthalate-glycol, polycyclohexylenedimethylene terephthalate, or polyethylene terephthalate with diethylene glycol. Preferably the polyester comprises poly(ethylene terephthalate) ("PET"), e.g., unmodified PET, polybutylene terephthalate (PBT), and the like.

[0020] Poly(phenylene ether)s can include those comprising repeating structural units having the formula

wherein each occurrence of Z¹ is independently halogen, unsubstituted or substituted C_1-12 hydrocarbyl provided that the hydrocarbyl group is not tertiary hydrocarbyl, C_1-12

hydrocarbylthio, C_1-12 hydrocarbyloxy, or C_2-12 halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms; and each occurrence of Z² is independently hydrogen, halogen, unsubstituted or substituted C1-12 hydrocarbyl provided that the hydrocarbyl group is not tertiary hydrocarbyl, C_1-12 hydrocarbylthio, Ci-i2 hydrocarbyloxy, or C_2-12 halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms. As one example, Z¹ can be a di-n-butylaminomethyl group formed by reaction of a terminal 3, 5-dimethyl-1,4-phenyl group with the di-n-butylamine component of an oxidative polymerization catalyst.

[0021] The polyketone compositions have less than 15 wt% polyamides, preferably less than 10 wt% polyamides, more preferably less than 5 wt% polyamides, or even less than 2 wt% polyamides, based upon a total weight of the polyketone compositions. The polyketone compositions can be free of polyamides.

[0022] In some embodiments, the polyketone compositions can further optionally include at least one compatibilizer, for example, styrene-ethylene-butadiene-styrene (SEES), styrene-butadiene-styrene (SBS), acrylonitrile-butadiene-styrene (ABS), polystyrene (PS), and the like.

[0023] When present, the additional polymer, the compatibilizer, or a combination thereof, is used in an amount from more than 0 to 50 wt%, greater than 0 to 40 wt%, greater than 0 to 30 wt%, greater than 0 to 20 wt% or greater than 0 to 10 wt%, all based on the total weight of the polyketone compositions. The sum of the weights of the aliphatic polyketone, the additional polymer (if present), and the compatibilizer (if present) can be greater than 85 wt%, greater than 90 wt%, or greater than 95 wt% based on the total weight of the polyketone compositions. In an embodiment, no polymer other than the aliphatic polyketone, the additional polymer, or the compatibilizer is present in the polyketone compositions. In another embodiment, no polymer other than the aliphatic polyketone and the optional compatibilizer is present in the polyketone compositions.

[0024] The polyketone compositions can include various additives ordinarily incorporated into polymer compositions of this type, with the proviso that the additive(s) are selected to not adversely affect the desired properties of the polyketone compositions, in particular, impact, flow, and chemical resistance. Such additives can be mixed at a suitable time during the mixing of the components for forming the housings. Exemplary additives include reinforcing agents, antioxidants, flow promoters, mold release agents, flame retardants, and thermally conductive additives. A combination of additives can be used. The total amount of additives (other than any impact modifier, filler, or reinforcing agents) can be 0.001 weight percent (wt%) to 25 wt%, 0.01 wt% to 15 wt%, or 0.01 wt% to 10 wt%, based on the total weight of the polyketone compositions.

[0025] The polyketone compositions have excellent chemical resistance. For example, a sample of the polyketone compositions can retain greater than 90% of tensile strength at yield and greater than 90% of tensile elongation at break after immersed in a mixture of dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate with a volume ratio of 1:1:1 at 60°C for 7 days determined according to ASTM D 638-14.

[0026] As another example, a sample of the polyketone compositions can retain greater than 90% of tensile strength at yield and greater than 85% of tensile elongation at break after immersed in a mixture of dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate with a volume ratio of 1:1:1 at 60°C for 14 days determined according to ASTM D 638-14.

[0027] The polyketone compositions can be extruded or injection molded to form housings directly. Alternatively, polyketone compositions can be extruded or molded into sheets, which are shaped to form the housings for battery cells.

[0028] Referring to FIG. 1, in some embodiments the battery cell housing 100 includes a body 10 and a top cover 20, where the body 10 can be molded from the polyketone compositions disclosed herein. The top cover 20 can be also made from the polyketone compositions. The terminals 30 for the battery cell can be positioned on the top cover 20.

[0029] Referring to FIG. 2, in other embodiments, the battery cell housing 150 includes a body 15, a top cover 22, and a bottom cover 25, wherein the body 15, the top cover 22, the bottom cover 25, or a combination thereof, can be extruded from the polyketone compositions disclosed herein. The terminals 35 for the battery cell can extend through the top cover 22 from inside the body 15. The body 15, top cover 22, and bottom cover 25 can be assembled together using mechanical and/or chemical methods, such as fasteners, adhesives, or welding (e.g., laser welding). Other known techniques can also be used.

[0030] The thickness of the housings can vary depending upon the specific battery cells selected and materials employed. Illustratively, the housings can have a thickness of 0.2 millimeter to 1.5 millimeters.

[0031] The battery cell housing can be a single layered structure or a multi-layered structure. A single layer structure means that the battery housing has only one layer, and that layer is made from the polyketone compositions disclosed herein. A multi-layered structure means that the battery housing has two or more layers, wherein at least one layer is a polyketone layer made from the polyketone compositions as disclosed herein and at least one layer is made from at least one material including a polyolefin (such as polypropylene), a polyester (such as a polyethylene terephthalate and a polybutylene terephthalate) or a metal.

[0032] Co-extrusion can be used to produce cell housings having a multi-layered structure. In a battery cell housing having a multi-layered structure, the polyketone layer can be the layer that is in direct physical contact with the electrolyte. As a specific example, the battery cell housings have a polyketone inner layer that is in direct physical contact with the electrolyte and a polyethylene terephthalate outer layer In an embodiment, no additional insulation materials are needed between battery housings of different battery cells.

[0033] The battery cell housings have excellent chemical resistance and are particularly useful in applications that have direct physical contact with electrolyte solvents. Examples of electrolyte solvents include but are not limited to acids, bases, and non-aqueous solvents such as alkyl carbonates. Methyl carbonate, ethyl carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, or the like are specifically mentioned. The battery cell housings can also have excellent chemical resistance to various electrolytes used in battery cells. Such electrolytes include, but are not limited to, sulfuric acid, potassium hydroxide, lithium salts such as lithium hexafluorophosphate, ionic liquids, fluorinated electrolytes, and the like.

[0034] Battery cells having the housing formed from polyketone compositions are also disclosed. The battery cells include the housing, an electrolyte, a positive electrode (cathode), a negative electrode (anode), and a separator disposed between the anode and cathode. The materials and configuration (if applicable) for the electrolyte, electrodes, and separator are known and not particularly limited. The battery cells can be cylindrical cells, prismatic cells, or pouch cells. Referring to FIG. 3, an example of battery cell 200 includes a housing 220, a cathode 280, an anode 210, and a separator 270 disposed between the cathode 280 and anode 210. The battery cell 200 also includes an insulator 260, a cathode tab or terminal 240 and an anode tab or terminal 230. Electrolyte 255 is disposed within and in direct physical contact with the housing 220.

[0035] The battery cells can be used in lithium ion batteries such as lithium iron phosphate batteries, ternary lithium batteries, solid-state lithium ion batteries, and the like. As used herein, lithium ion batteries include rechargeable lithium ion batteries.

[0036] Preferably the battery cells are those that used in electric vehicles, hybrid vehicles, and plug-in hybrid electric vehicles. More than one battery cells can be used.

Accordingly, also disclosed is a battery system or battery pack comprising a plurality of electrically connected battery cells, e.g., connected in series, or connected in parallel, or connected in a combination thereof.

[0037] The above described and other features are exemplified by the following examples. In the examples, unless otherwise specified, the percent (%) of the components is weight percent based on the total weight of the composition.

EXAMPLES

[0038] The materials used in the example are described in Table 1 and 2, and the standard tests performed are summarized in Table 2.

Molding

[0039] The molding conditions are shown in Table 3. Standard testing bars were prepared for testing.

Example

[0040] The example evaluates the chemical resistance of polyketone in a lithium ion battery electrolyte solvent. A molded sample of a polyketone (100%) was immersed in an electrolyte solvent shown in Table 1 in a sealed container at a temperature of 60°C for 7 or 14 days. The weight, tensile performance, and surface moiphology were analyzed before and after the chemical resistance test. The results are shown in Tables 4 and 5 as well as FIGS. 4-

6.

Table 5.

[0041] The data in Table 4 shows that there is no weight reduction after a tensile bar of polyketone was immersed in the electrolyte solvent for 7 days at 60°C.

[0042] It was observed that the surface morphology of the sample was maintained after the immersion test, indicating that the polyketone sample has excellent chemical resistance to electrolyte solvents.

[0043] The SEM images of the sample before and after the immersion are shown in FIGS. 4 to 6. The SEM images also confirm that the surface morphology was maintained after the immersion test.

[0044] The data in Table 5 shows that the tensile bars of polyketone have excellent tensile retention after immersion test with a tensile strength at yield retention of 91% and a tensile elongation at break retention of 92.4% after 7 days exposure to the electrolyte solvent at 60°C. In addition, the tensile bars of polyketone have a tensile strength at yield retention of 90.1% and a tensile elongation at break retention of 85.1% after 14 days exposure to the electrolyte at 60°C.

[0045] Further included in this disclosure are the following specific aspects, which do not necessarily limit the claims.

[0046] Aspect 1. A battery cell comprising: a housing comprising a polyketone layer formed from a polyketone composition comprising 50 to 100 wt% of an aliphatic polyketone derived from carbon monoxide and a C_2-6 alpha olefin; and preferably less than 15 wt% of polyamides; wherein the weight percent is based on the total weight of the polyketone composition; an electrolyte enclosed within and in direct physical contact with the polyketone layer; an anode and a cathode that are each in contact with the electrolyte; a separator separating the anode from the cathode; and a first terminal and a second terminal electrically coupled to the anode and cathode respectively and extending outwardly from the housing.

[0047] Aspect 2. The battery cell of Aspect 1 , wherein the polyketone composition comprises 90 wt% to 100 wt% of the aliphatic polyketone.

[0048] Aspect 3. The battery cell of Aspect 1 or Aspect 2, wherein the aliphatic polyketone is derived from carbon monoxide and ethylene.

[0049] Aspect 4. The battery cell of Aspect 1 or Aspect 2, wherein the aliphatic polyketone is derived from carbon monoxide, ethylene, and propylene.

[0050] Aspect 5. The battery cell of any one of Aspects 1 to 4, wherein the aliphatic polyketone has a melt flow index of greater than 5 g/10 min measured according to ASTM D1238-13 at 240°C with a load of 2.16 kilograms, and a notched Izod impact strength of greater than 90 J/m determined according to ASTM D256-10 at 23°C.

[0051] Aspect 6. The battery cell of any one of Aspects 1 to 5, wherein the polyketone composition further comprises at least one of a polyolefin, a polyester, a polyphenylene ether, and a poly(phenylene ether).

[0052] Aspect 7. The battery cell of any one of Aspects 1 to 6, wherein the polyketone composition further comprises at least one of a compatibilizer, a flame retardant, a reinforcement filler, a flow promoter, an anti-oxidant, a mold release agent, and a thermally conductive additive.

[0053] Aspect 8. The battery cell of any one of Aspects 1 to 7, wherein a sample of the polyketone composition retains greater than 90% of tensile strength at yield and greater than 90% of tensile elongation at break after immersed in a mixture of dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate with a volume ratio of 1:1 :1 at 60°C for seven days.

[0054] Aspect 9. The battery cell of any one of Aspects 1 to 8, wherein the electrolyte comprises a non-aqueous solvent.

[0055] Aspect 10. The battery cell of Aspect 9, wherein the non-aqueous solvent comprises one or more alkyl carbonates.

[0056] Aspect 11. The battery cell of any one of Aspects 1 to 10, wherein the housing has a single layered structure.

[0057] Aspect 12. The battery cell of any one of Aspects 1 to 10, wherein the housing has a multi-layered structure, preferably the multi-layered structure has the polyketone layer formed from the polyketone composition, and an additional layer comprising a polyolefin, a polyester, or a metal.

[0058] Aspect 13. The battery cell of any one of Aspects 1 to 12, wherein the housing is an extruded or an injection molded article.

[0059] Aspect 14. The use of a polyketone composition comprising 50 to 100 wt% of an aliphatic polyketone derived from carbon monoxide and a C_2-6 alpha olefin in the manufacture of a battery cell housing that is in direct physical contact with an electrolyte solvent, provided that the polyketone composition comprises less than 15 wt% of polyamides based on the total weight of the polyketone composition.

[0060] Aspect 15. A battery system comprising a plurality of electrically connected battery cells of any one of Aspects 1 to 13.

[0061] The singular forms“a,”“an,” and“the” include plural referents unless the context clearly dictates otherwise.“Or” means“and/or” unless clearly indicated otherwise by context. Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. A“combination” is inclusive of blends, mixtures, alloys, reaction products, and the like.

“One or more of the foregoing” means at least one the listed material.

[0062] Unless otherwise specified herein, any reference to standards, regulations, testing methods and the like refers to the standard, regulation, guidance or method that is in force as of January 1, 2018.

[0063] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

[0064] While typical embodiments have been set forth for the purpose of illustration, the foregoing descriptions should not be deemed a limitation on the scope herein.

Accordingly, various modifications, adaptations, and alternatives can occur to one skilled in the art without departing from the spirit and scope herein.

Claims

CLAIMS We claim:

1. A battery cell comprising:

a housing comprising a polyketone layer formed from a polyketone composition comprising

50 to 100 wt% of an aliphatic polyketone derived from carbon monoxide and a

C_2-6 alpha olefin; and

less than 15 wt% of polyamides;

wherein the weight percent is based on the total weight of the polyketone composition;

an electrolyte enclosed within and in direct physical contact with the polyketone layer; an anode and a cathode that are each in contact with the electrolyte;

a separator separating the anode from the cathode; and

a first terminal and a second terminal electrically coupled to the anode and cathode respectively and extending outwardly from the housing.

2. The battery cell of claim 1, wherein the polyketone composition comprises 90 wt% to 100 wt% of the aliphatic polyketone.

3. The battery cell of claim 1 or claim 2, wherein the aliphatic polyketone is derived from carbon monoxide and ethylene.

4. The battery cell of claim 1 or claim 2, wherein the aliphatic polyketone is derived from carbon monoxide, ethylene, and propylene.

5. The battery cell of any one of claims 1 to 4, wherein the aliphatic polyketone has a melt flow index of greater than 5 g/10 min measured according to ASTM D1238-13 at 240°C with a load of 2.16 kilograms, and a notched Izod impact strength of greater than 90 J/m determined according to ASTM D256-10 at 23°C.

6. The battery cell of any one of claims 1 to 5, wherein the polyketone composition further comprises at least one of a polyolefin, a polyester, a polyphenylene ether, and a poly(phenylene ether).

7. The battery cell of any one of claims 1 to 6, wherein the polyketone composition further comprises at least one of a compatibilizer, a flame retardant, a reinforcement filler, a flow promoter, an anti-oxidant, a mold release agent, and a thermally conductive additive.

8. The battery cell of any one of claims 1 to 7, wherein a sample of the polyketone composition retains greater than 90% of tensile strength at yield and greater than 90% of tensile elongation at break after immersed in a mixture of dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate with a volume ratio of 1 :1:1 at 60°C for seven days.

9. The battery cell of any one of claims 1 to 8, wherein the electrolyte comprises a non-aqueous solvent.

10. The battery cell of claim 9, wherein the non-aqueous solvent comprises one or more alkyl carbonates.

11. The battery cell of any one of claims 1 to 10, wherein the housing has a single layered structure.

12. The battery cell of any one of claims 1 to 10, wherein the housing has a multi layered structure, preferably the multi-layered structure has the polyketone layer formed from the polyketone composition, and an additional layer comprising a polyolefin, a polyester, or a metal.

13. The battery cell of any one of claims 1 to 12, wherein the housing is an extruded or an injection molded article.

14. The use of a polyketone composition comprising 50 to 100 wt% of an aliphatic polyketone derived from carbon monoxide and a C_2-6 alpha olefin in the manufacture of a battery cell housing that is in direct physical contact with an electrolyte solvent, provided that the polyketone composition comprises less than 15 wt% of polyamides based on the total weight of the polyketone composition.

15. A battery system comprising a plurality of electrically connected battery cells of any one of claims 1 to 13.