ELECTRICAL INTERCONNECTIONS FOR BATTERY CELLS

Abstract

Battery pack, including: a pouch cell (10, 100, 200, 300) having electrode webs (16, 20, 116, 120, 208, 216, 238, 300, 308) extending therefrom, each of which defines perforations (126); a busbar (130, 230, 330) in contact with the webs (16, 20, 116, 120, 208, 216, 238, 300, 308); and corresponding agglomerations (132, 232, 238, 323, 332) of mechanically bonded solid metal particles, each filling one of the perforations (126) to mechanically and electrically connect the webs (16, 20, 116, 120, 208, 216, 238, 300, 308) to the busbar (130, 230, 330).

Description

SUBJECT AREA

[0001] The disclosure relates to bag-shaped ion battery cells and methods for their manufacture. STATE OF THE ART

[0002] Lithium-ion pouch cells have been used in a wide variety of industries, including automotive applications. These pouch-shaped cell designs are attractive due to their lower weight and cost, optimized space utilization at the battery level, higher specific gravity, and higher output voltage per cell than many other systems. This has made lithium-ion energy systems the first choice for many applications. Conventional electrical interconnections of pouch cells are implemented as fixed threaded studs or ultrasonically welded webs, which can be subject to mechanical inconsistencies, high contact resistance, bonding inconsistencies, and other problems. Both solutions also present the challenge of connecting a busbar to tabs formed from dissimilar metals.

[0003] Alternative methods for providing battery interconnects have been developed, such as thermal spraying. However, processes such as arc or plasma spraying expose the pouch cell to temperatures of up to 20,000°C. Furthermore, bonds created by thermal spraying can be compromised by oxide deposits.

[0004] US 2006 / 0 113 359 A1 discloses secure physical connections produced by a kinetic spraying process. JP 2014 022 141 A discloses an electrical connection component. WO 2012 118 127 A1 discloses a non-aqueous secondary battery. JP 2014 135 203 A discloses a square secondary battery. SUMMARY

[0005] In at least one embodiment, a battery pack is disclosed. The battery pack comprises a pouch cell having electrode lands extending therefrom, each defining perforations. The battery pack further comprises a busbar in contact with the lands, and corresponding agglomerations of mechanically bonded solid metal particles, each filling one of the perforations to mechanically and electrically connect the lands to the busbar. Each land may include at least one row of perforations. The perforations may be circular. The perforations within at least one of the lands may have different dimensions. The perforations may be arranged in a regular pattern. The agglomerations may cover at least a portion of the lands. The agglomerations may be free of voids, oxide inclusions, or both. Each of the particles may have a discrete crystalline structure.

[0006] In another embodiment, a battery pack is disclosed. The battery pack includes a busbar and a pair of pouch cells. A perforated web extends from each of the pouch cells, the pouch cells being arranged side by side such that the perforated webs are positioned for contact with the busbar and interlock with each other. The battery pack further includes an agglomeration of solid metal particles mechanically bonded to each other, to the perforated webs, and to the busbar such that they electrically connect the perforated webs to the busbar. The first perforated web may include a pair of pins. The adjacent perforated webs may include interconnected pins. The pins of the first perforated web may have different dimensions than the pins of the second perforated web. The webs may each include at least one perforation.The agglomeration may be free of voids, oxide inclusions, or both.

[0007] In yet another embodiment, a battery pack is disclosed. The battery pack may include a bus bar and a plurality of pouch cells. Each pouch cell may extend a ridge of a different height than other pouch cells, and the ridges may be arranged side by side such that the ridges are aligned with and form a terrace with each of the ridges contacting the bus bar. The battery pack may further include respective agglomerations of mechanically bonded solid metal particles layered over one end of each ridge and a portion of the bus bar to electrically connect the ridges to the bus bar. A height of the first ridge may be at least 50% of a height of a second ridge. The plurality of pouch cells may include at least three cells. The ridges may have a different chemical composition.

[0008] At least some of the lands are narrower than the width of the busbar. The agglomerations may be free of voids, oxide inclusions, or both. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1A shows an exploded view of individual layers within a pouch cell battery, which in Fig. 1B is shown; Fig. 1B shows a perspective view of an exemplary pouch cell battery; Fig. 2 shows a perspective view of an exemplary pouch cell connected to an exemplary bus bar according to one or more embodiments. Fig. 3A-3C show in detail exemplary perforation patterns on webs used in Fig. 2 are shown; Fig. 4A shows a perspective view of a portion of an exemplary battery pack with perforated webs; Fig. 4B shows an alternative embodiment of the Fig. 4A battery packs shown with perforated bars; Fig. 4C shows the battery pack from Fig. 4A or Fig. 4B with openwork webs connected to the busbar; Fig. 5 shows a perspective view of a portion of an alternative exemplary battery pack having lands connected to the bus bar forming a terrace; Fig. 6 shows a schematic representation of an exemplary cold spray system comprising an agglomerate-substrate contact surface produced in a cold spray system; Fig. 7A-7D show changes in particle-substrate contact area when a solid particle impacts a surface of a substrate during a cold spray coating process; Fig. Figure 8 shows a perspective schematic representation of a coating-substrate contact surface produced by a thermal spray coating process; and Fig. Figure 9 shows a schematic representation of an agglomerate-substrate contact surface, which Fig. 2, Fig. 4C and Fig. 5 forms the intermediate connections shown. DETAILED DESCRIPTION

[0009] Embodiments of the present disclosure are described herein. It should be understood, however, that the disclosed embodiments are merely examples and that other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, certain structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. As one of ordinary skill in the art will appreciate, various features illustrated and described with reference to one of the figures may be combined with one or more features illustrated in other figures to form embodiments not expressly illustrated or described herein.The illustrated feature combinations provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of this disclosure may be desirable for particular applications or implementations.

[0010] Unless expressly stated, all numerical quantities in this specification indicating dimensions or material properties are to be understood as modified by the word "about" when describing the broadest scope of the present disclosure.

[0011] The initial definition of an acronym or other abbreviation applies to all subsequent uses of the same abbreviation and, accordingly, to normal grammatical variations of the initially defined abbreviation. Unless explicitly stated otherwise, the measurement of a property is performed using the same measurement method previously or subsequently specified for the same property.

[0012] The description of a group or class of materials as suitable for a given purpose in the context of one or more embodiments of the present invention implies that mixtures of one or more members of the group or class are suitable. Descriptions of constituents in chemical formulas refer to constituents at the time of addition to a combination specified in the description and do not necessarily preclude chemical interactions between constituents of the mixture after mixing. The first definition of an acronym or other abbreviation applies to all subsequent uses of the same abbreviation and, accordingly, to normal grammatical variations of the initially defined abbreviation. Unless expressly stated otherwise, the measurement of a property is by the same measurement method previously or subsequently specified for the same property.

[0013] With the mass production of batteries, a variety of battery formats have been developed. Examples of battery formats include cylindrical cells, button cells, prismatic cells, and pouch cells. The pouch cell design represents efficient space utilization, achieving a packaging efficiency of 90–95%. Instead of using a metal cylinder and a glass-to-metal electrical feedthrough, conductive foil webs are typically welded to the electrodes and completely sealed while extending outward from the pouch. By eliminating a metal housing, the weight of the pouch cell is reduced.

[0014] While a pouch cell represents a lightweight solution for battery construction, the pouch format requires several considerations, including storage and expansion space. Furthermore, exposure to moisture and high temperatures can shorten cell lifetime. Swelling is another issue; for example, swelling of 8-10% over 500 cycles is normal for some types of pouch cells. However, pouch cells have become popular, particularly when they meet the same performance criteria as cylindrical cells. Pouch cells have been successfully used in consumer, military, and automotive applications. Relatively large, flat pouch cell batteries have been used in electric powertrains and energy storage systems. Relatively small pouch cells have been used for portable applications with high charge current requirements.

[0015] An exemplary lithium ion pouch cell battery 10 is shown in Fig. 1A and Fig. 1B. As shown in Fig. 1A and Fig. 1B, the pouch cell 10 has an architecture laminated within a pouch 12. The pouch 12 includes a cathode 14 with a battery land or terminal 16, an anode 18 with a battery land or terminal 20, and a separator 22 disposed between the cathode 14 and the anode 18. After the laminated layers 14, 18, and 22 are joined together and inserted into the pouch 12, the pouch 12 is filled with electrolyte and then sealed so that the lands 16 and 20 are outside the pouch 12.

[0016] The pouch cells 10 are typically lithium-ion batteries with a liquid electrolyte. The electrolyte can be gelled by adding a polymer additive. The cells 10 are also referred to as LiPo for lithium polymer. However, a variety of alternative electrochemical processes involving lithium ions can be utilized. The lands or terminals 16, 20 of the lithium-ion pouch cell 10 typically have different chemical properties because they are internally connected to the cathode 14 and anode 18, which are formed of dissimilar metals. The current collectors, the cathode 14 and the anode 18, are usually made of copper, aluminum, or nickel foil. The lands 16, 20 are typically formed of the same metal as the respective electrodes 14, 18 to avoid creating a galvanic cell between the electrode and the lands.The presence of webs 16, 20 made of dissimilar metals presents a challenge when connecting the webs 16, 20 to a busbar, because the incompatibility of the metals can lead to increased corrosion, increased resistance, and a lack of robustness of the joint.

[0017] The electrode interconnections between the bars and the busbar traditionally consisted of fixed threaded pins or ultrasonically welded bars. The latter exhibit a number of problems, such as inconsistent bonding and fatigue of the fixture (horn and anvil). Fixed threaded studs, on the other hand, can lead to mechanical failure and high contact resistance.

[0018] To avoid the aforementioned disadvantages, thermal spray coating processes have been used to form the interconnections between the busbar and the electrode terminals. Many of the processes utilize high-temperature thermal spray processes to apply the solderable material. Thermal spray coating processes are generally processes that allow the layer-by-layer deposition of a wide range of starting materials onto a substrate at high deposition rates. However, these processes use relatively high temperatures, which cause the material to melt. In thermal spray processes, the bond is created by mechanical interlocking and can be enhanced by elevated temperature or particle velocities.However, the high processing temperatures generally increase the amount of oxides embedded in the coating, reducing the coating's performance for structural applications and potentially damaging the cell. For example, the cell separator 22 typically has a relatively low temperature tolerance, which limits the processes that can be used. Example thermal spray processes and the temperature ranges typically associated with them include a plasma spray process with temperatures between 9,727°C (10,000 K) and 19,727°C (20,000 K), arc metal spray with temperatures of approximately 14,727°C (15,000 K), coating with a coating gun at temperatures of approximately 5,227°C (5,500 K), or a high velocity oxyfuel deposition (HVOF) coating process with temperatures of approximately 5,227°C (5,500 K).

[0019] It would therefore be desirable to design interconnections between electrode terminals and busbar in such a way as to eliminate high-wear tools such as horns and anvils from the assembly process, mitigate bond delamination and full-thickness cracking typical of ultrasonic welding, reduce degradation and parasitic inductance by producing dense, layered coatings with low porosity and oxidation, and provide superior corrosion resistance and low electrical resistance while maintaining process temperatures that prevent cell destruction or the creation of oxide inclusions.

[0020] In one or more embodiments described in Fig. 2, a battery pack 124 is disclosed. The battery pack includes a pouch cell 100 having a cathode land 116 and an anode land 120 extending from pouch 112. Lands 116, 120 are aligned with a bus bar 130 such that lands 116, 120 are in contact with bus bar 130. Lands 116, 120 may be made of copper, aluminum, nickel, zinc, lead, and the like, or a combination thereof. A protective layer may be formed on the surface of one or more of the lands to promote bonding of the lands to the bus bar. The protective layer may include nickel, titanium, zinc, silver, gold, tin, and the like, or a combination thereof. Land 116 may be made of the same or a different material than land 120.The surface of one or both of the webs 116, 120 may be at least partially smooth or textured to increase the surface area for bonding between the webs 116, 120 and the busbar 130.

[0021] The webs 116, 120 include one or more perforations 126. Each perforation 126 is filled with an agglomeration 132 of mechanically bonded solid metal particles that enable the bonding of the webs 116, 120 to the busbar 130. The perforations 126 may be partially filled with the agglomerated material 132 such that at least a portion of a perforation 126 remains free of the agglomerated material 132. Alternatively, the entire surface area of ​​the busbar 130 that is in contact with and defined by the perforation 126 may be covered with the agglomerated material 132. The agglomerations 132 may cover at least a portion of the webs 116, 120. The perforations 126 can be filled with the metal particles forming the agglomerations 132 such that corresponding agglomerations 132 are not in contact with each other.As a further alternative, an agglomeration 126 may fill and / or cover more than one perforation 126. An agglomeration 132 may have a thickness that does not exceed a thickness of the web 116, 120. Alternatively, the agglomeration 132 may have a thickness greater than the thickness of the web 116, 120. An agglomeration 132 may have a diameter that does not exceed a diameter of a perforation 126. Alternatively, a diameter of an agglomeration 132 may be greater than a diameter of the perforation 126.

[0022] The webs described herein may include one or more perforations 126. A plurality of perforations 126 may contribute to better thermal conductivity than the presence of only a single perforation 126. Additionally, providing a plurality of perforations 126 increases the number of locations for coating the agglomerations 132, which in turn contributes to increased joint robustness and reduces the possibility of adhesion failure between the webs and the busbar.

[0023] The webs 116, 120 may include the same or a different number of perforations 126, which may be the same or different in shape, cross-section, dimensions, orientation, and other characteristics. Exemplary perforations 126 are shown in Fig. 3A-3C. While Fig. 3A-3C show the web 116 and perforations 126, the web 116 and the perforations 126 are merely examples and the description applies to each web and perforation described herein. As in Fig. 3A, the land 116 may include perforations 126 arranged at a regular distance from one another. The perforations 126 may have a cross-section that is a circle, an ellipse, a square, a rectangle, a pentagon, a heptagon, an octagon, a nonagon, a trapezoid, a triangle, a star, a four-leaf clover, a kite, a regular shape, an irregular shape, a symmetrical shape, an asymmetrical shape, and the like, or a combination thereof. The perforations 126 may have an edge 128 that is smooth, uneven, ridged, rough, jagged, and the like, or a combination thereof. In one or more embodiments, some of the perforations 126 may have an edge 128 that is not smooth. Alternatively, some of the perforations 126 may have smooth and rough portions. The roughness may provide additional surface area for binding. An exemplary smooth edge 128 is shown in Fig. 3A, and an exemplary serrated edge 128 is shown in Fig. 3B. The web 116 may comprise one or more rows of perforations 126. Webs 116 with only one row of perforations are shown in Fig. 3A and Fig. 3B, while an example of a web 116 with several rows of perforations in Fig. 3C is shown.

[0024] The perforations 126 may comprise approximately less than 5%, 5%, 10%, 20%, 30%, 40%, 50%, or more of the surface area of ​​the land. The dimensions of one perforation 126 may differ from the dimensions of at least one other perforation 126. Alternatively, all perforations 126 may have the same dimensions. All lands 116, 120 may have the same pattern of perforations 126. The pattern may be regular or irregular, symmetrical or asymmetrical. Alternatively, a land may comprise a different pattern of perforations 126 than at least one other land. Providing the same pattern of perforations 126 for all lands may simplify the manufacturing process. Nevertheless, application-specific adaptation is conceivable, whereby different patterns may be advantageous, for example, if corresponding lands have a different thickness and / or material composition.The perforations 126 in the webs may be provided by a number of processes, for example by pressing, punching, cutting, embossing, another type of pretreatment, or a combination thereof.

[0025] In a further embodiment, which is Fig. 4A-4C, a battery pack 224 is disclosed. The battery pack 224 includes pouch cells 200. The pouch cells 200 may form a pair. Alternatively, the battery pack 224 may include more than two pouch cells 200. Extending from each pouch cell 200 is an openwork web 208. The openwork web 208 may be a cathode web 216 or an anode web 218. Alternatively, either only the cathode web or only the anode web 216, 220 may be an openwork web 208, while the other web is not of an openwork construction.

[0026] The openwork web 208 has one or more pins 238 separated by a gap. The overall profile of the openwork web 208 resembles a castle wall with battlements. The number, shape, orientation, location, and dimensions of the pins 238 and the gap 207 can vary. For example, as shown in Fig. 4A, a first openwork web 208 may have two pins 238, while a second openwork web 208 may have three pins 238. Any number of pins 208 is conceivable, as long as the pins of the adjacent webs 208 interlock to make contact with the busbar 230. The pins 230 may have the same or different dimensions, shapes, or the like. For example, the pins 238 may have rounded edges. Alternatively, the edges of the pins 238 may be flat, uneven, regular, irregular, jagged, curved, tapered, grooved, toothed, smooth, and the like, or a combination thereof. As best seen from Fig. As can be seen in Figure 4B, each openwork web may include three corresponding pins. The first web 208' includes three pins 238' of the same dimensions and shape, with each pin 238' having a generally rectangular shape with a flat top and corrugated sides with a plurality of wave crests and troughs. The second web 208" has three pins 238", two of which have a lower height than the third pin 238" and the pins 238' of the first web 208'. The pins 238" of the second web 208" facing the pins 238' of the first web 208' have corrugated sides with corrugation crests corresponding to the corrugation troughs of the pins 238' and corrugation troughs corresponding to the corrugation crests of the pins 238'. The above-mentioned properties of the pins 238', 238" of the two webs 208', 208" must enable the perforated webs 208 to interlock and contact the busbar 230.

[0027] Alternatively, the pins 238 may have a square or rectangular shape with pointed corners. The height and / or width of the plurality of pins 238 may be the same, or the height, width, or both dimensions of a pin 238 may differ from at least one other pin 238. For example, the pins 238 located in the center of a web 208 may have larger dimensions than the remaining pins 238. Any dimensions, shapes, orientations, and locations of a pin 238 within the web 208 are conceivable, as long as the at least two webs 208 are open and interlock.

[0028] As in Fig. 4A and Fig. 4B with respect to two exemplary lands 208 in contact with each other, the lower portions 242 of the lands 208 may be aligned and stacked such that the lower portions 242 of the lands 208 are in direct contact with each other. On the other hand, the pins 238 forming the upper portions 244 of the lands 208 are not in contact with each other. Instead, the pins 238 interlock and are interlaced like fingers of clasped hands, while a gap 240 remains between the interlocking pins 238 of the two contacting lands 208. In one or more embodiments, at least some of the pins 238 may overlap. The lands 208 may include one or more of the perforations 126 described above.

[0029] The top and / or side edge(s) of at least one of the bags 212 may, but need not, be flush. For example, Fig. As can be seen in Figures 4A-4C, the top and side edges of the first and second bags are flush with each other.

[0030] An agglomeration 232 of solid metal particles is mechanically bonded to the perforated webs 208 and the busbar 230. The agglomeration 232 thus forms interconnections 234 that electrically connect the webs 208 to the busbar 230. In one or more embodiments described in Fig. 4C, the interconnects 234 are formed by a single elongated strip of the agglomerated material 232 creating a coating or overlay 236. The agglomeration 232 may be continuous or intermittent. Alternatively, the interconnects 234 may include more than one corresponding agglomeration 232. For example, a set of corresponding agglomerations 232 may be applied over the superimposed perforated lands 208 and the busbar 230. An exemplary application of the agglomerations 232 may include a set of corresponding agglomerations forming strips filling the one or more gaps 240 between the respective interdigitated pins 238 of at least two lands 208. Further, alternatively, individual agglomerations 238 covering the gap 240 may be combined with one or more elongated overlays of the agglomerations 238.

[0031] In yet another embodiment, which is Fig. 5, a battery pack 324 is disclosed. The battery pack 324 includes a plurality of pouch cells 300. Each pouch cell 300 has lands 308 extending therefrom to a different height than other lands 308 of other pouch cells 300. The pouch cells 300 are arranged side by side such that the lands 308 of different heights are aligned with each other and form a terrace 342 with each of the lands 308 contacting the bus bar 330. The terrace 342 resembles the flat surfaces created on the side of a hill for growing crops, for example, stepped rice paddies. The individual flat surfaces are formed by corresponding agglomerations of mechanically bonded solid metal particles, each layered over an end portion 346 of the individual lands 308 and a portion of the bus bar 330.The end portions 346 may comprise approximately less than 5%, 5%, 10%, 20%, 30%, 40%, or less than 50% of the surface area of ​​the respective web 308. The agglomerations 323 thus form interconnections that electrically connect the webs 308 to the busbar 330.

[0032] As in Fig. 5, the terrace 342 includes a first land 308' or the first pouch cell 300', wherein the land 308' is aligned with the busbar 330 such that the busbar 330 and the land 308' abut each other. An agglomeration 323' connects the first web 308' to the busbar 330. The second web 308" has a greater height than the first web 308' such that the second web 308' contacts the busbar 330 while being aligned with the first web 308'. An agglomeration 323" is applied to the busbar 330 and the upper part of the second web 308". The third agglomeration 323''' is similarly applied to the busbar 330 and the third web 308''', which has a greater height than the second web 308", such that the third web 308''' contacts the busbar 330. The top and / or side edge(s) of at least one of the pouches 312 may, but need not, be flush. As shown, for example, in Fig. As can be seen in Figure 5, the top and side edges of the first, second and third bags are flush with each other.

[0033] While the Fig. 5 shows three agglomeration layers 323', 323", and 323", a larger or smaller number of agglomeration layers is conceivable and depends on the number of cells 300 that must be connected to the battery pack 324. Likewise, the dimensions and shape of the webs 308 and the dimensions, shape, and location of the agglomerations 323 in the battery pack 324 can be the same or different and correspond to those described above. The different dimensions can relate to the height, width, thickness, or a combination thereof. The dimensions of the webs 308 can be different, as long as all webs 308 have direct contact with the busbar 330. The height, width, and / or thickness of the webs 308 can be smaller than the height, width, and / or thickness of the busbar 330.The height, width, and / or thickness difference between the smallest and largest webs 308 may be approximately less than 10%, 10%, 20%, 30%, 40%, 50%, 60%, or more. The location of the agglomerations 323 may be at the top 346 of the respective web 308, at one or more side edges 348 of the web 308, or at both locations. The agglomeration 323 may be continuous or discontinuous.

[0034] For example, the height of the webs 308 may be different, as described above with reference to Fig. 5. Alternatively, the height of the respective webs 308 may be the same, but their widths may be different, so that the web 308' of the pouch cell 300 closest to the busbar 330 has the smallest width. An agglomeration 323" is applied to the side edges 348 and / or the top edge / end portion 346 of the web 308'. A second web 308' having a greater width than the first web 308' is aligned with the first web 308', and an agglomeration is applied to the side edge 348 and optionally to the top edge / end portion 346 of the second web 308''. An additional web 308''' or further webs 308, each of increasing width, can be placed on top of the previous web and coated with an agglomeration. A final agglomeration layer can be applied when all webs 308 are stacked and attached to the busbar 330 via the agglomerations 323.

[0035] The agglomerations 132, 232, 332 form the battery interconnects 134, 234, 334. The interconnects are thus formed as an agglomeration of solid particles that are mechanically bonded to each other and to the substrate by plastic deformation. The substrate includes the busbar 130, 230, 330 and the webs 116, 216, 316, 120, 220, 320. The agglomeration of particles can be formed using a cold spray coating process, also known as gas dynamic cold spray (GDCS). Cold spray coating is an impact solidification process. Cold spray coating differs from the hot spray processes mentioned above in that a much lower temperature is used, for example an ambient temperature of about 24°C (297.15 K) to about 80°C (353.15 K), so that the material applied to a substrate remains in an elastic but solid state.The temperature can be increased beyond the above-mentioned range to achieve better formability and softness of the particles, as long as the elevated temperature is below the melting point of the particles and the substrate. Thus, cold spray coating is a process for applying particles without phase change. Since no phase change occurs, all particles in the agglomeration have the same thermomechanical history, resulting in uniform properties of the intermediate compounds.

[0036] During cold spray coating, powdered metal particles are applied to a substrate by ballistic impact at supersonic speed, forming a multi-layer coating or a free-form structure. An exemplary schematic representation of a cold spray system 50 is shown in Fig. 6. The system 50 includes a powder feeder 52 for accepting a powder feed material 54 having a particle size of approximately 1-100 µm in diameter.

[0037] The feed material 54 may comprise a powder of metals such as Mg, Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Rh, Pd, Ag, In, Sn, Hf, Ta, W, Ir, Pt, Au, Re, polymers, ceramics, composites, metal matrix composites, nanocrystal materials, or a mixture thereof. Individual particles of the feed material may be soft, hard, stiff, smooth, rough, or the like.

[0038] An exemplary powder feed rate may be 1-10 pounds / hour. The system 50 further includes a gas inlet 56 for supplying gas that can entrain the solid particles 58. The gas may be, for example, N2, He, a mixture thereof, or the like. A heater 60 is provided for heating the guide gas to approximately 100-500°C to increase the deformability of the particles 58 to be applied to the substrate 62. The gas flow rate may be approximately 30-100 CFM. The powder coating material 54 is introduced at high pressure and temperature at the inlet of the supersonic nozzle 64. The gas expands and is accelerated through the nozzle 64 as its temperature decreases. Rapid changes occur at the nozzle orifice 66, where the gas reaches supersonic speed. The speed and temperature of the solid particles 58 approach those of the gas as heat transfer occurs.

[0039] Due to the high pressure and high temperature in the cold spray system 50, supersonic gas velocities such as 300-1500 m / s and a high particle acceleration in the gas stream 68 can be achieved. The solid particles 58 are carried in the gas stream 68 and directed towards the substrate 62, in which they embed themselves upon impact and form a strong bond with the surface of the substrate 62. The kinetic energy of the particles 58 caused by the expansion of the gas is converted into plastic deformation energy during the bonding. In order to achieve particle consolidation with the surface, a critical velocity must be reached before the particles 58 impact the substrate 62. The critical velocity varies depending on the feed type. Since the particles 58 remain in the solid state and are subjected to plastic deformation, they can, upon impact, as in Fig. 7A-7D shown lens-shaped.

[0040] Fig. 7A-7D show a sequence of changes at the particle-substrate contact surface 70 when the solid particles 58 impact the surface of the substrate 62. As can be seen from Fig. As can be seen in Figures 7A-7D, upon impact of particle 58 onto substrate 62, particle 58 is flattened, while a crater 72 forms in substrate 62. The depth and width of crater 72 increase over time, such that w1 < w2 and h1 < h2. At the same time, the temperature at the impact zone rises, with the increase concentrated at particle-substrate contact surface 70. Nevertheless, the discrete crystalline structure of solid particle 58 is preserved upon impact. The resulting bond between solid particles 58 and substrate 62 creates mechanical mixing at particle-substrate contact surface 70, similar to explosive bonding.

[0041] In contrast to the particles 58 applied by cold spraying in Fig. 7A-7D will be in Fig. 8 illustrates a coating-substrate interface 80 formed of molten particles 82 thermally sprayed onto a substrate 84. The resulting structure includes molten particles / material 82, voids 86, oxide inclusions 88, and unmolten particles 90.

[0042] It is advantageous that the mechanical mixing of the cold spray coating at the particle-substrate contact surface 70 does not allow for voids that are normally associated with the coating-substrate contact surface 80 produced by thermal spraying processes. An exemplary consolidated coating with solid powder particles 58 forming the interconnections, which is described herein as a void-free structure, is shown in Fig. 9. As can be seen from Fig. As can be seen in Figure 9, the thickness of the applied particle layer or agglomerate 132 can be increased by adding an additional amount of solid particles 58. In the formed agglomeration 132, the additional amount of particles 58 mechanically mixes with the already applied solid particles 58. No voids are created in the agglomerate 132. The particle-substrate contact surface 70 and the particle-particle contact surface 74 are free of voids and oxide inclusions.

[0043] Because the interconnects 134, 234, 334 can be made of materials such as copper and aluminum, which are sensitive to the presence of oxygen and readily oxidize at elevated temperatures, the thermal spray process can produce interconnects of inferior quality. The particle melting that occurs with most thermal spray processes, which can lead to oxidation of the coating and substrate and thus reduce module performance, does not occur with the cold spray process. The agglomerate 132 and the particle-substrate contact surface 70 produced during the cold spray process are thus free of oxide inclusions that could otherwise reduce the bond strength and cohesive force of the coating 136 forming the interconnects 134, 234, 334. The interconnects 134, 234, 334 are thus applied as a dense coating 136 with a low oxide content of less than 0.3 to 0.5%.The coating 136 is a non-porous or low-porosity structure with a porosity of less than 0.5% to 2%. However, the coating 136 has physical properties, such as strength, comparable to or exceeding those of some wrought materials. The exemplary bond strength of the particles 58 to each other and to the substrate 62 may be about 10 to 60 MPa or more, about 15 to 40 MPa or more, or about 15 to 25 MPa or more.

[0044] In one or more embodiments, a method for directly cold spray coating the electrical interconnections 134 is disclosed. Fig. The method illustrated in Figure 2 for fabricating interconnects 134 comprises providing a pouch cell 100 having lands 116, 120. Lands 116, 120 are perforated. The method involves perforating lands 116, 120 by one or more of the methods described above. Perforated lands 116, 120 are then aligned with busbar 130. The alignment results in the majority of the surface area of ​​lands 116, 120 being in direct contact with the surface of busbar 130. The method further comprises forming agglomerations 132 of solid metal particles within perforations 126, as described above. The solid particles are mechanically mixed with the substrate, busbar 130, wherein agglomerations 132 are free of voids and / or oxide inclusions.The agglomerations 132 can form one or more layers of different dimensions, shapes, positions, configurations, or a combination thereof. To prevent the agglomerations 132 from being applied elsewhere, a shield or mask can be positioned over the cell 200, which shield or mask prevents the application of spray material outside the target areas. The agglomerations 132 forming the interconnections 134 can be applied by cold spraying using the method described above.

[0045] The dimensions of the applied material, such as height, width, and thickness, of each interconnect 134 can be varied as needed for a particular application. Likewise, at least some of the interconnects 134 can be made of a different material than the remaining interconnects 134. All interconnects 134 can be formed at the same time, or a first portion of the interconnects 134 can be formed before a second portion of the interconnects 134 is formed by cold spray coating. The cold sprayed interconnects 134 can be planar, compact structures applied as a relatively flat coating 30, thus utilizing space more efficiently than welded interconnects or threaded studs.

[0046] In another embodiment, a method for forming interconnects 234 that is described in Fig. 4A-4C. The method includes providing a plurality of cells 200 having perforated lands 208 as described above. The method further includes aligning the perforated lands 208 with the bus bar 230. The alignment may be such that the bottom portions 242 of the lands 208 overlap one another, while the top portions 244 have interlocking pins 238. The alignment may include aligning the top and / or side edge(s) flush with one another. The interlocking pins 238 may be oriented such that their sides are in contact with adjacent pins 238. Alternatively, the method may include interlocking the lands 238 such that the corresponding pins 238 are not in contact with one another and a gap 240 may be formed between adjacent pins 238.The method further comprises applying solid metal particles forming agglomerations 232 to end portions / top portions 244 of the interdigitated pins 238 and to a portion of the busbar 230. The coating may also be directed toward and at least partially fill the one or more gaps 240. Additionally, an agglomeration 232 may cover one or more side edges of the pins 238. The interconnects 234 may be formed as a single connected layer, for example, as an elongated strip, or as corresponding agglomerations 232 that are not in contact with each other. The method may comprise applying the interconnects 234 as one or more layers that differ in dimensions, location, orientation, shape, and the like, or a combination thereof.An agglomeration 232 forming the interconnections 234 can be applied over the entire surface of an interlocking, perforated web 208 in contact with the busbar 230. Alternatively, only a portion of the webs 208 overlying the busbar 230 can be covered with the agglomerated material 232. The amount of agglomerated material 232 should be sufficient to ensure proper mating of the busbar 230 and the webs 208, prevent delamination, and simultaneously establish a good electrical connection. A mask can be applied as described above.

[0047] One in Fig.The method for forming interconnects 334 illustrated in Figure 5 is further described herein. The method includes, as described above, providing a plurality of cells 300 having perforated lands 308 characterized as above. The method may include aligning the cells 300 and / or lands 308 such that, for example, the top edges of the cells 300, the top and / or side edge(s) of the lands 308, or a combination thereof are flush with one another. The method includes contacting a first cell 300' having a first land 308' with the busbar 330 such that a top / end portion 346 of the land 308' overlies a bottom portion of the busbar 330. An agglomeration 332 of solid metal particles is then applied to the land 308' and the busbar 330.The method includes disposing a second cell 300'' having a second land 308'' over the first agglomeration 323' and the first land 308' such that the second land 308'' is in contact with the busbar 330. In particular, the second land 308'' is in contact with the portion of the busbar 330 that is above the upper edge of the first agglomeration 323'. A third cell 300''' having a third land 308''' can be similarly disposed in contact with the busbar 330, the second agglomeration 323'', and the second land 308''. Additional lands 300 can be provided, with the application of each additional land 308 followed by the application of an additional agglomeration 323. Thus, layered or stepped interconnections 234 are created.As described above, the webs 308 may be of different widths, heights, and / or thicknesses as long as the interconnections 334 form a terrace 342. The dimensions of the agglomerations 332 between respective webs 308 may be the same or different in terms of dimensions, shape, location, orientation, and the like, or a combination thereof.

[0048] The above methods may involve attaching the same or a different number of cells to each side of a busbar. More than one of the methods described herein may be used to form interconnections of a single battery pack.

[0049] While the dielectric material and / or interconnections of modules 100, 200, 300 can be formed using any type of cold spray process, a kinetic metallization process can offer several advantages. For example, the kinetic metallization process operates at sonic speeds and pressures of approximately 50 to 130 psig, which is lower than some other cold spray processes, which can require up to 700 psig. The lower pressure allows the process to be performed using a smaller amount of gas, for example, up to 1 / 10 of the gas required by other types of cold spray processes.

[0050] While exemplary embodiments are described above, these embodiments are not intended to describe all possible forms of the disclosure. The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. Furthermore, the features of the various embodiments may be combined to form further embodiments of the disclosure.

Claims

[1] Battery pack, comprising: a pouch cell (10, 100, 200, 300) having electrode webs (16, 20, 116, 120, 208, 216, 238, 300, 308) extending therefrom, each of which defines perforations (126); a busbar (130, 230, 330) in contact with the webs (16, 20, 116, 120, 208, 216, 238, 300, 308); and corresponding agglomerations (132, 232, 238, 323, 332) of mechanically bonded solid metal particles, each filling one of the perforations (126) to mechanically and electrically connect the webs (16, 20, 116, 120, 208, 216, 238, 300, 308) to the busbar (130, 230, 330). [2] Battery pack according to claim 1, wherein the perforations (126) are circular. [3] Battery pack according to claim 1, wherein the perforations (126) within at least one of the webs (16, 20, 116, 120, 208, 216, 238, 300, 308) have different dimensions. [4] Battery pack according to claim 1, wherein the perforations (126) are arranged in a regular pattern. [5] Battery pack according to claim 1, wherein the agglomerations (132, 232, 238, 323, 332) cover at least a part of the webs (16, 20, 116, 120, 208, 216, 238, 300, 308). [6] Battery pack, comprising: a busbar (130, 230, 330); a pair of pouch cells (10, 100, 200, 300) from which a perforated web extends, which are arranged side by side such that the perforated webs (16, 20, 116, 120, 208, 216, 238, 300, 308) are arranged for contact with the busbar (130, 230, 330) and interlock; and an agglomeration (132, 232, 238, 323, 332) of solid metal particles which are mechanically bonded to one another, to the perforated webs (16, 20, 116, 120, 208, 216, 238, 300, 308) and to the busbar (130, 230, 330) in such a way that they electrically connect the perforated webs (16, 20, 116, 120, 208, 216, 238, 300, 308) to the busbar (130, 230, 330). [7] The battery pack of claim 6, wherein a first perforated web comprises a pair of pins. [8] Battery pack according to claim 6, wherein adjacently arranged perforated webs comprise pins in contact with each other. [9] Battery pack according to claim 8, wherein the pins of the first perforated web may have different dimensions than the pins of the second perforated web. [10] Battery pack according to claim 1 or 6, wherein each web (16, 20, 116, 120, 208, 216, 238, 300, 308) comprises at least one row of perforations (126). [11] Battery pack, comprising: a busbar (130, 230, 330); a plurality of pouch cells (10, 100, 200, 300), from each of which extends a web of a different height compared to other of the pouch cells (10, 100, 200, 300), arranged side by side such that the webs (16, 20, 116, 120, 208, 216, 238, 300, 308) are aligned with each of the webs (16, 20, 116, 120, 208, 216, 238, 300, 308) contacting the busbar (130, 230, 330) and form a terrace (342); and corresponding agglomerations (132, 232, 238, 323, 332) of mechanically bonded solid metal particles extending in a layered manner over one end of the individual webs (16, 20, 116, 120, 208, 216, 238, 300, 308) and a part of the busbar (130, 230, 330) in order to electrically connect the webs (16, 20, 116, 120, 208, 216, 238, 300, 308) to the busbar (130, 230, 330). [12] Battery pack according to claim 11, wherein the height of a first web is at least 50% of the height of a second web. [13] The battery pack of claim 11, wherein the plurality of pouch cells (10, 100, 200, 300) comprises at least three cells. [14] Battery pack according to claim 11, wherein at least some of the webs (16, 20, 116, 120, 208, 216, 238, 300, 308) have a width less than the width of the busbar (130, 230, 330). [15] Battery pack according to one of the preceding claims, wherein the agglomeration(s) (132, 232, 238, 323, 332) are free of voids, oxide inclusions or both.

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