Method for partial anodization of a battery cell

Abstract

A battery pack for a vehicle includes a plurality of prismatic battery cells. The plurality of prismatic battery cells include a battery casing for housing a negative electrode, a positive electrode, a separator, and an electrolyte. The battery casing includes: at least one sidewall including a first end and a second end opposite to the first end; a bottom wall connected to the first end defining a volume, an inner surface of the battery casing, and an outer surface of the battery casing; and a top cover mates with the second end. At least one of the sidewall, bottom wall, and top cover is formed of aluminum and anodized. The battery pack also includes a thermal interface material (TIM) having a top surface and a bottom surface opposite to the top surface. The battery pack also includes a cold plate.

Description

Technical Field

[0001] This invention relates to a method for partially anodizing battery cells. More specifically, this invention relates to a method for partially anodizing prismatic battery cells to form an electrically insulating, thermally conductive, thermally stable, and mechanically abrasion-resistant layer. Background Technology

[0002] The realization of electric and hybrid vehicle technologies is made possible by the development and deployment of rechargeable secondary batteries, which provide energy for vehicle powertrains. Secondary batteries consist of prismatic cell units, typically including a positive electrode, a negative electrode, a separator, and an electrolyte. During charging, ions migrate from the positive electrode to the negative electrode. The ions are stored in the negative electrode and released back to the positive electrode when energy is needed. The separator prevents the positive and negative electrodes from coming into contact, avoiding short circuits. The electrolyte provides the medium for ions to migrate between the positive and negative electrodes.

[0003] Prismatic battery casings are typically made of aluminum, which necessitates preventing short circuits and arcing within and between battery cells. Polymer materials are commonly used as insulators to prevent short circuits; for example, polyphenylene sulfide (PPS) is used in the top cover of the prismatic battery cell, and a polyethylene terephthalate (PET) film is used around the casing. However, adding polymer materials to the prismatic battery cells increases the thickness of each cell. Furthermore, PET's low thermal conductivity hinders heat dissipation. The PET film also absorbs moisture, which negatively impacts the integrity of the prismatic battery casing.

[0004] Therefore, although the current method of using PET film to wrap prismatic battery cells for insulation has achieved its intended purpose, a new and improved method is still needed to improve battery insulation and promote heat dissipation while reducing the thickness of each prismatic battery cell, such as by partially anodizing the prismatic battery cells. Summary of the Invention

[0005] According to several aspects, a battery pack for a vehicle is provided. The battery pack includes a plurality of prismatic battery cells. The plurality of prismatic battery cells include a battery casing for housing a negative electrode, a positive electrode, a separator, and an electrolyte. The battery casing includes at least one sidewall having a first end and a second end. The battery casing also includes a bottom wall connected to the first end of the at least one sidewall defining a volume, an inner surface of the battery casing, and an outer surface of the battery casing. The battery casing also includes a top cover mateable with the second end of the at least one sidewall. At least one of the at least one sidewall, the bottom wall, and the top cover is formed of aluminum and anodized. The battery pack also includes a thermal interface material (TIM). The TIM has a top surface and a bottom surface, with the bottom surface opposite the top surface. The top surface is adjacent to the bottom wall of the battery casing. The battery pack also includes a cold plate. The cold plate is adjacent to the bottom surface of the TIM.

[0006] In another aspect of the invention, the outer surface is formed of aluminum, and a portion of the outer surface of the battery casing is anodized.

[0007] In another aspect of the invention, the outer surface of the second end of at least one sidewall is not anodized. The unanodized second end of at least one sidewall is fitted to the top cover by laser welding.

[0008] In another aspect of the invention, the outer surface of the bottom wall is anodized and is in direct contact with the TIM.

[0009] In another aspect of the invention, the outer surface of at least one sidewall of a plurality of prismatic battery cells is anodized and is in direct contact with at least one sidewall of an adjacent prismatic battery cell.

[0010] In another aspect of the invention, the top cover is formed of aluminum, and the center of the top cover is anodized. The edges of the top cover are not anodized. The unanodized edges of the top cover are laser welded to at least one sidewall.

[0011] In another aspect of the invention, the battery casing further includes an anodic oxide layer. This anodic oxide layer is densified.

[0012] In another aspect of the invention, the battery casing further includes an anodic oxide layer. This anodic oxide layer is porous and contains pores. These pores are filled with one of the following: a flame retardant, a thermally conductive agent, and TIM epoxy resin.

[0013] According to several aspects, a prismatic battery cell for a vehicle is provided. The prismatic battery cell includes a battery casing for housing a negative electrode, a positive electrode, a separator, and an electrolyte. The battery casing includes at least one sidewall having a first end and a second end opposite to the first end. The battery casing also includes a bottom wall connected to the first end of the at least one sidewall defining a volume, an inner surface of the battery casing, and an outer surface of the battery casing. The battery casing also includes a top cover capable of engaging with the second end of the at least one sidewall. At least one of the at least one sidewall, the bottom wall, and the top cover is formed of aluminum and anodized.

[0014] In another aspect of the invention, the inner surface is formed of aluminum, and a portion of the inner surface of the battery casing is anodized.

[0015] In another aspect of the invention, the inner surface of the second end of at least one sidewall is not anodized. The unanodized second end of at least one sidewall is fitted to the top cover by laser welding.

[0016] In another aspect of the invention, the outer surface is formed of aluminum, and a portion of the outer surface of the battery casing is anodized.

[0017] In another aspect of the invention, the outer surface of the second end of at least one sidewall is not anodized. The unanodized second end of at least one sidewall is fitted to the top cover by laser welding.

[0018] In another aspect of the invention, the top cover is formed of aluminum, and the center of the top cover is anodized. The edges of the top cover are not anodized. The unanodized edges of the top cover are laser-welded to at least one sidewall.

[0019] According to several aspects, a method for anodizing a battery casing is provided. The method includes forming a cellcan for the battery casing. The battery casing includes at least one sidewall having a first end and a second end opposite to the first end. The battery casing also includes a bottom wall connected to the first end of the at least one sidewall defining a volume, an inner surface of the battery casing, and an outer surface of the battery casing. The battery casing also includes a top cover mateable with the second end of the at least one sidewall. At least one of the at least one sidewall, the bottom wall, and the top cover is formed of aluminum and anodized. The method further includes covering a portion of the battery casing with acid. The method further includes applying a power source to the battery casing to anodize the covered portion of the battery casing.

[0020] In another aspect of the invention, a portion of the outer surface of the battery casing is coated with acid. The outer surface is formed of aluminum, and this portion of the outer surface is anodized.

[0021] In another aspect of the invention, covering a portion of the inner surface of the battery casing includes filling the volume defined by the battery casing with acid. The inner surface is formed of aluminum, and this portion of the inner surface is anodized.

[0022] In another aspect of the invention, the method further includes shielding a portion of the battery casing before covering that portion with acid.

[0023] In another aspect of the invention, the edges of the top cover are masked and the center of the top cover is anodized. The top cover is formed of aluminum. The edges of the top cover are not anodized. The method also includes removing the masking material and welding the unanodized edges of the top cover to at least one sidewall of the battery casing.

[0024] In another aspect of the invention, the method further includes removing any obstructions on that portion of the battery casing and welding the top cover to at least one sidewall.

[0025] Further applicability will become apparent from the description provided herein. It should be understood that the specification and specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Attached Figure Description

[0026] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

[0027] Figure 1A A vehicle comprising a battery pack having a plurality of prismatic battery cells is shown according to an exemplary embodiment.

[0028] Figure 1B An enlarged view of a battery pack having multiple prismatic battery cells according to an exemplary embodiment is shown.

[0029] Figure 2A A prismatic battery cell according to an exemplary embodiment is shown.

[0030] Figure 2B An exploded view of the top cover of a prismatic battery cell according to an exemplary embodiment is shown.

[0031] Figure 3 An isometric view of a prismatic battery cell according to an exemplary embodiment is shown, wherein the outer surface of the prismatic battery cell has an anodized portion, specifically anodized a portion of the bottom wall and at least one side wall.

[0032] Figure 4 An isometric view of a prismatic battery cell according to an exemplary embodiment is shown, wherein the outer surface of the prismatic battery cell has an alternative anodized portion.

[0033] Figure 5 An isometric view of a prismatic battery cell according to an exemplary embodiment is shown, wherein the inner surface of the prismatic battery cell has an anodized portion.

[0034] Figure 6 A top view of a prismatic battery cell with an anodized portion having a top cover, according to an exemplary embodiment, is shown.

[0035] Figure 7A An anodized prismatic battery cell with a porous anodized layer is shown according to an exemplary embodiment.

[0036] Figure 7B An anodized prismatic battery cell with a dense anodized layer is shown according to an exemplary embodiment.

[0037] Figure 8 A method for a portion of anodizing a prismatic battery cell is shown. Detailed Implementation

[0038] The following description is exemplary in nature only and is not intended to limit the invention, application, or use. Furthermore, it is not intended to be bound by any express or implied theory set forth in the foregoing background, summary of the invention, or the following detailed description. It should be understood that throughout the drawings, corresponding reference numerals denote the same or corresponding parts and features.

[0039] Reference will now be made in detail to several examples of the invention illustrated in the accompanying drawings. Wherever possible, the same or similar reference numerals will be used in the drawings and description to refer to the same or similar parts or steps. The drawings are simplified and not drawn to scale.

[0040] This invention relates to a method for partially anodizing a battery cell. More specifically, this invention relates to a method for partially anodizing a prismatic battery cell to form an electrically insulating, thermally conductive, thermally stable, and mechanically abrasion-resistant layer. This prismatic battery cell can be used in electric or hybrid electric vehicles.

[0041] The term "vehicle" as used herein is not limited to automobiles. While this technology is primarily described in conjunction with electric and hybrid electric vehicles, it is not limited to electric and hybrid electric vehicles. These concepts can be used in a wide variety of applications, such as those related to components used in motorcycles, mopeds, locomotives, aircraft, ships, and other vehicles, as well as other battery-powered applications such as consumer electronics, mobile power supplies for buildings, portable power stations for powering remote construction sites, emergency backup power supplies, and permanent power stations associated with buildings and equipment. All of these applications can be powered by, for example, solar or wind power systems, power grids, and fuel generators (e.g., gasoline, propane, kerosene, or diesel generators and Stirling engines).

[0042] refer to Figure 1A The image shows a vehicle 10 including a battery pack 12 for supplying power to an electric motor 14. The battery pack 12 includes a plurality of battery modules 16 electrically connected to each other. Each battery module 16 includes a plurality of prismatic battery cells 18 disposed within the battery module 16. The battery pack 12 also includes a thermal interface material (TIM) 20 and a cold plate 22.

[0043] Figure 1B An enlarged view of the battery pack 12 is shown, which includes a thermally conductive membrane (TIM) 20 and a cold plate 22. The TIM 20 and cold plate 22 help manage the temperature of the multiple prismatic battery cells 18 within the battery pack 12. The TIM 20 is located between the multiple prismatic battery cells 18 and the cold plate 22. The top surface 24 of the TIM 20 is close to the prismatic battery cells 18, while the bottom surface 26 is opposite the top surface 24 and close to the cold plate 22. The TIM 20 may take the form of, but is not limited to, a compressible thermally conductive pad, liquid-dispensed and curing adhesives, non-curing gels, and greases. Furthermore, the TIM 20 may also be formulated from silicone, polyurethane, epoxy, and acrylic resins. The TIM 20 helps transfer heat generated by the prismatic battery cells 18 to the cold plate 22. The cold plate 22 absorbs heat from the prismatic battery cells 18 through the TIM 20 and keeps the multiple prismatic battery cells 18 within an optimal temperature range to ensure their performance and safety.

[0044] Refer again Figure 1A It should be understood that Figure 1A This is merely illustrative in nature, and the multiple battery modules 16 are not limited to being used as secondary batteries for a vehicle. In fact, the battery modules 16 can be used in a variety of other electric vehicles and stationary applications. It should also be understood that although the vehicle 10 is shown as a passenger car, the vehicle 10 can be any type of vehicle, such as, but not limited to, a truck, SUV, van, or motorhome.

[0045] refer to Figure 2A This shows the method for using vehicle 10 (such as...) Figure 1A (Shown) One of a plurality of prismatic battery cells 18 powered by electricity. It should be understood that each of the plurality of prismatic battery cells 18 is identical, therefore only one prismatic battery cell 18 will be described herein. Prismatic battery cell 18 includes a negative electrode 28, a positive electrode 30, a separator 32, an electrolyte 34, and a battery casing 36.

[0046] As described above, the prismatic battery cell 18 is a secondary battery, which can be understood as a rechargeable battery. The prismatic battery cell 18 can discharge when a load is applied and charge when an external power source is applied. The motor 14 (e.g.) Figure 1A As shown, a load is applied to the prismatic battery cell 18, causing ions to move from the negative electrode 28 through the separator 32 to the positive electrode 30 via the electrolyte 34. When an external voltage is applied, ions move from the positive electrode 30 through the separator 32 to the negative electrode 28 via the electrolyte 34. The movement of ions through the electrolyte 34 generates electrical energy. Ions can be stored in the negative electrode 28. When energy is needed, the negative electrode 28 releases ions and returns them to the positive electrode 30. The negative electrode 28, positive electrode 30, separator 32, and electrolyte 34 are housed within the battery casing 36 to prevent leakage.

[0047] The battery casing 36 may be formed of aluminum and includes a battery canister 38 and a top cover 40. The battery canister 38 includes a bottom wall 41 and at least one side wall 42. The bottom wall 41 is connected to a first end 44 of the at least one side wall 42 defining a volume, an outer surface 46 of the battery casing 36, and an inner surface 48 of the battery casing 36. The outer surface 46 of the bottom wall 41 may be connected to the top surface 24 of the TIM 20 (e.g., ...). Figure 1B The outer surface 46 of at least one sidewall 42 is in direct contact with the adjacent prismatic battery cell 18. The inner surface 48 is adjacent to the negative electrode 28, the positive electrode 30, the separator 32, and the electrolyte 34. To encapsulate the negative electrode 28, the positive electrode 30, the separator 32, and the electrolyte 34 within the battery casing, the top cover 40 mates with the second end 58 of at least one sidewall 42. The second end 58 is opposite to the first end 44 of at least one sidewall 42.

[0048] Figure 2B The prismatic battery cell 18 is shown (e.g.) Figure 2A An exploded view of the top cover 40 (shown). The top cover 40 has a layered structure, including a positive terminal subplate 60, a negative terminal subplate 62, multiple terminal insulators 64, a vent 66, a cover 68, a cover insulator 70, multiple gaskets 72, and multiple spacers 74.

[0049] The positive terminal plate 60 and the negative terminal plate 62 can be made of aluminum, but are not limited to this. The positive terminal plate 60 provides a positive connection point for external electrical contacts. The negative terminal plate 62 provides a negative connection point for external electrical contacts. The motor 14 (e.g.) Figure 1A (As shown) Connected to the positive terminal plate 60 and the negative terminal plate 62, thus forming a closed circuit. The closed circuit allows electrons to flow from the negative terminal plate 62 through the motor 14 and to the positive terminal plate 60, thereby converting electrical energy into mechanical energy.

[0050] Multiple terminal insulators 64 are located between and in direct contact with the positive terminal plate 60, the negative terminal plate 62, and the cover 68. The multiple terminal insulators 64 may be formed of polyphenylene sulfide (PPS), but are not limited to this. The multiple terminal insulators 64 ensure electrical insulation between the positive terminal plate 60 and the negative terminal plate 62, preventing short circuits in the prismatic battery cell 18.

[0051] Vent 66 and cover 68 may be formed of aluminum, but are not limited to this. Vent 66 allows for the release of pressure within the prismatic battery cell 18. Vent 66 is attached to cover 68. Cover 68 is part of top cover 40 and is welded to at least one second end 58 of sidewall 42 (e.g., Figure 2A (as shown), and provides structural support and protection for the prismatic battery cell 18.

[0052] The cover insulator 70, multiple gaskets 72, and multiple spacers 74 may be formed of PPS, but are not limited to this. The cover insulator 70 is located between the cover 68 and the multiple gaskets 72. The cover insulator 70 forms an insulating layer that separates the cover 68 from the negative electrode 28, positive electrode 30, and electrolyte 34 within the prismatic battery cell 18. The multiple gaskets 72 are located between the cover insulator 70 and the multiple spacers 74. The multiple gaskets 72 form a seal to prevent leakage of the electrolyte 34. The multiple spacers 74 keep the cover 68 properly aligned and separate the cover 68 from the negative electrode 28, positive electrode 30, and electrolyte 34.

[0053] At least a portion of the battery casing 36 of the prismatic battery cell 18 is anodized. In one embodiment, the anodized portion of the battery cell is formed of aluminum. (Reference) Figure 3 An embodiment of an anodized portion 76 of the outer surface 46 of a prismatic battery cell 18 is shown. The anodized portion 76 is formed by anodizing the outer surface 46 of the bottom wall 41 and the height 78 of the outer surface 46 of at least one sidewall 42. The outer surface 46 of the bottom wall 41 may have an arcuate angle 80 connecting to a first end 44 of at least one sidewall 42. The arcuate angle 80 has a radius of curvature and a height 78 determined by the radius of curvature, thereby ensuring that the entire outer surface 46 of the bottom wall 41 is anodized. The outer surface 46 of the bottom wall 41 may be colored anodized. Colored anodizing can represent different battery chemistry properties and allows for visual inspection of the anodizing process.

[0054] refer to Figure 4 The diagram shows an alternative or additional anodized portion 76 of the outer surface 46 of the prismatic battery cell 18, designated by reference numeral 82. The anodized portion 82 is formed by anodizing a portion of the outer surface 46 of the bottom wall 41 and the outer surface 46 of at least one sidewall 42. The anodized portion 82 of the outer surface 46 can be color-anodized. Color anodizing can represent different battery chemistry properties and allows for visual inspection of the anodizing process. The second end 58 of at least one sidewall 42 remains unanodized, thereby allowing the second end 58 to mate with the top cover 40 using laser welding or other welding processes.

[0055] refer to Figure 5The diagram shows an anodized portion 84 of the inner surface 48 of the prismatic battery cell 18. The anodized portion 84 is formed by anodizing the inner surface 48 of the bottom wall 41 and the inner surface 48 of at least one side wall 42. The second end 58 of at least one side wall 42 remains unanodized, thereby allowing the second end 58 to mate with the top cover 40 using a welding process such as laser welding.

[0056] Figure 3-5 Alternate or additional anodized portions 76, 82, and 84 of the bottom wall 41 and at least one side wall 42 of the prismatic battery cell 18 are shown. Anodizing the prismatic battery cell 18 improves electrical insulation performance during thermal runaway propagation (TRP) and produces a higher resistivity (>1.1014 Ω). Due to the improved electrical insulation performance, it is unnecessary to cover the outer surface 46 of the prismatic battery cell 18 with a polyethylene terephthalate (PET) film. This allows the outer surface 46 of the bottom wall 41 to be in direct contact with the top surface 24 of the TIM 20 (e.g., ...). Figure 1B As shown), and such that the outer surface 46 of at least one sidewall 42 can directly contact the adjacent prismatic battery cell 18 (as shown). Figure 1B (As shown). Furthermore, removing the PET film reduces the thickness of each prismatic cell 18, thereby allowing for a higher density of prismatic cell 18 within a similar cell pack volume.

[0057] refer to Figure 6 The diagram shows the anodized portion 86 of the top cover 40 of the prismatic battery cell 18. The top cover 40 includes a center 88 and an edge 90. The center 88 of the top cover is anodized. The edge 90 is not anodized, which allows the top cover 40 to mate with the second end 58 of at least one sidewall 42 by laser welding or other welding processes. Anodizing the anodized portion 86 of the top cover 40 enhances the thermomechanical properties and electrical insulation around the positive terminal plate 60 and the negative terminal plate 62, areas that are typically at higher temperatures. Furthermore, anodizing the anodized portion 86 suppresses arcing between the positive terminal plate 60 and the negative terminal plate 62 and grounds the battery casing 36.

[0058] refer to Figure 7A and 7B The diagram shows the anodic oxide layers 92 and 94 on the prismatic battery cell 18. The anodic oxide layers 92 and 94 are the anodic oxide portions 76, 82, 84, and 86 of the prismatic battery cell 18 (e.g., ...). Figure 3-6 (as shown) is a layer on top. The anodizing process for forming anodized portions 76, 82, 84 and 86 will be described in more detail below.

[0059] After the anodizing process, Figure 7AThe anodic oxide layer 92 shown is porous. The thickness of the anodic oxide layer 92 is in the range of 100 nanometers (nm) to 100 micrometers (μm), including all values ​​and ranges within this range. The porosity of the anodic oxide layer 92 is approximately 5% to 50%, where porosity refers to the percentage of pore volume in the total given volume defined by the anodic oxide layer. The porosity of the anodic oxide layer 92 improves the stability of the prismatic cell 18. The prismatic cell 18 may be formed of aluminum, and the aluminum is converted into aluminum anodic oxide (AAO), thereby forming a porous layer and forming pores 96. Pores 96 may be filled with chemicals such as thermally conductive agents, TIM epoxy resin, or flame retardants. Flame retardants may be, but are not limited to, triethyl phosphate (TEP), trimethyl phosphate (TMP), triphenyl phosphate (TPP), or dimethyl methylphosphonate (DMMP). In the initial stage of thermal runaway propagation (TRP) in the prismatic cell 18, thermally conductive agent, TIM epoxy resin, or flame retardant is released from the pores 96, thereby slowing the rapid rise of thermal runaway propagation (TRP).

[0060] refer to Figure 7B This illustrates an alternative or additional anodic oxide layer 92 on the prismatic cell 18, designated by reference numeral 94. The thickness of the anodic oxide layer 94 ranges from 100 nm to 100 μm, including all values ​​and ranges therein. The anodic oxide layer 94 is densified with a porosity of approximately 1% to 10%. To form the anodic oxide layer 94, a sealing process is required after the anodizing process. For example, the prismatic cell 18 can be formed from aluminum. Aluminum becomes aluminum anolyte (AAO) after the anodizing process, which is originally porous. The AAO can then be densified by immersing it in a sealing solution, thereby forming the anodic oxide layer 94. The densified anodic oxide layer 94 improves corrosion resistance and facilitates heat transfer between the prismatic cell 18 and the cold plate 22.

[0061] refer to Figure 8 The diagram shows a flowchart of a method 100 for anodizing a portion of a battery casing 36. In step 102, a battery can 38 for a battery cell 18 is formed. The battery can 38 is formed by connecting a bottom wall 41 to a first end 44 of at least one side wall 42.

[0062] In step 104, a shield may be attached to the battery housing 36. For example, the shield may be attached to the edge 90 of the top cover 40. The shield prevents anodizing of the portion of the battery housing 36 to which it is attached. The shield may be, but is not limited to, adhesive or tape.

[0063] In step 106, a portion of the battery casing 36 is covered with acid. This acid can be sulfuric acid. To cover the portion of the battery casing 36 with acid, a bath can be created. When using a bath, a portion of the battery casing 36 or the top cover 40 can be immersed in the acid. For example, the outer surface 46 of the bottom wall 41 and the height 78 of at least one side wall 42 can be immersed in the acid. In an alternative embodiment, the outer surface 46 of the bottom wall 41 and the outer surface 46 of at least one side wall 42 can be immersed in the acid, while the second end 58 of at least one side wall 42 remains outside the acid. In another alternative embodiment, the top cover 40 (with a shield attached to its edge 90) can be completely immersed in the acid bath, thereby preventing the edge 90 from contacting the acid. Alternatively, the volume defined by the battery casing 36 can be filled with acid. The inner surface 48 of the second end 58 of at least one side wall 42 does not contact the acid.

[0064] In step 108, power is applied to the portion of the battery casing 36 covered by acid. The covered portion of the battery casing 36 is connected to the positive terminal. An inert material is added to the acid, and the negative terminal is connected to this inert material. Current flows from the positive terminal, through the battery casing 36, through the acid, and to the negative terminal, anodizing the acid-covered portion of the battery casing 36. The battery casing 36 may be formed of aluminum, forming AAO after the anodizing process.

[0065] If the shield is attached to the battery housing 36 in step 104, the shield is removed in step 110. After the shield is removed, the portion covered by the shield is still not anodized.

[0066] In step 112, the edge 90 of the top cover 40 mates with the second end 58 of at least one sidewall 42. Neither the edge 90 of the top cover 40 nor the second end 58 of the at least one sidewall 42 is anodized for this mating. The edge 90 and the second end 58 may be mated by laser welding.

[0067] The method 100 disclosed herein for partially anodized battery casing 36 has numerous advantages. These advantages include improved electrical insulation performance and the generation of higher resistivity, while reducing the thickness of each prismatic battery cell 18.

[0068] The description of this invention is merely exemplary in nature, and any modifications that do not depart from the spirit and scope of this invention are intended to fall within its scope. Such modifications should not be considered as a departure from the spirit and scope of this invention.

Claims

1. A battery pack for a vehicle, the battery pack comprising: Multiple prismatic battery cells are disposed within a battery pack, wherein the multiple prismatic battery cells include: A battery casing for housing a negative electrode, a positive electrode, a separator, and an electrolyte, the battery casing comprising: At least one sidewall, the at least one sidewall comprising a first end and a second end opposite to the first end; A bottom wall, the bottom wall being connected to the first end of the at least one side wall defining the volume, the inner surface of the battery casing, and the outer surface of the battery casing; and A top cover, which can mate with the second end of the at least one sidewall. Wherein, at least one of the at least one sidewall, the bottom wall and the top cover is formed of aluminum and has undergone anodizing treatment; A thermal interface material (TIM), wherein the TIM has a top surface and a bottom surface, the bottom surface facing the top surface and the top surface adjacent to the bottom wall of the battery casing; and A cold plate, wherein the cold plate is adjacent to the bottom surface of the TIM.

2. The battery pack according to claim 1, wherein, The outer surface is formed of aluminum, and a portion of the outer surface of the battery casing is anodized.

3. The battery pack according to claim 2, wherein, The outer surface of the second end of the at least one sidewall is not anodized, and the unanodized second end of the at least one sidewall is fitted to the top cover by laser welding.

4. The battery pack according to claim 2, wherein, The outer surface of the bottom wall is anodized and is in direct contact with the TIM.

5. The battery pack according to claim 2, wherein, The outer surface of at least one sidewall of the plurality of prismatic battery cells is anodized and is in direct contact with at least one sidewall of an adjacent prismatic battery cell.

6. The battery pack according to claim 1, wherein, The top cover is made of aluminum, and the center of the top cover is anodized, while the edges of the top cover are not anodized. The unanodized edges of the top cover are laser welded to the at least one sidewall.

7. The battery pack according to claim 1, wherein, The battery casing also includes an anodized layer, which is densified.

8. The battery pack according to claim 1, wherein, The battery casing also includes an anodic oxide layer, which is porous and contains pores filled with one of the following: a flame retardant, a thermally conductive agent, and TIM epoxy resin.

9. A prismatic battery cell for a vehicle, the prismatic battery cell comprising: A battery casing for housing a negative electrode, a positive electrode, a separator, and an electrolyte, the battery casing comprising: At least one sidewall, the at least one sidewall comprising a first end and a second end opposite to the first end; A bottom wall, the bottom wall being connected to a first end of the at least one side wall defining the volume, an inner surface of the battery casing, and an outer surface of the battery casing; and A top cover, which can mate with the second end of the at least one sidewall. Wherein, at least one of the at least one sidewall, the bottom wall and the top cover is formed of aluminum and has undergone anodizing treatment.

10. The prismatic battery cell according to claim 9, wherein, The inner surface is formed of aluminum, and a portion of the inner surface of the battery casing is anodized.

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