HOLLOW PRISMATIC AND CYLINDRICAL BATTERY CELLS, METHOD FOR MANUFACTURING, AND BATTERY HEAT EXCHANGE SYSTEM

A battery system includes N hollow battery cells, each including an enclosure including a top surface, a bottom surface, and a side wall; a hollow center tube including a side wall and a cavity enclosed by the side wall, and a roll including electrode and separator layers arranged between an outer surface of the hollow center tube and the enclosure. The hollow center tube passes through at least one of the top surface and the bottom surface of the enclosure. A battery heat exchange system includes a first fluid channel including N ports configured to at least one of supply fluid to and receive fluid from at least one end of the hollow center tube of the N hollow battery cells.

INTRODUCTION

The present disclosure relates to battery cells, and more particularly to hollow battery cells and heat exchange systems for hollow battery cells.

Electric vehicles (EVs) such as battery electric vehicles (BEVs), hybrid vehicles, and/or fuel cell vehicles include one or more electric machines and a battery system including one or more battery cells, modules, and/or packs. A power control system is used to control charging and/or discharging of the battery system during charging and/or driving.

SUMMARY

A battery system includes N hollow battery cells, each including an enclosure including a top surface, a bottom surface, and a side wall; a hollow center tube including a side wall and a cavity enclosed by the side wall, and a roll including electrode and separator layers arranged between an outer surface of the hollow center tube and the enclosure. The hollow center tube passes through at least one of the top surface and the bottom surface of the enclosure. A battery heat exchange system includes a first fluid channel including N ports configured to at least one of supply fluid to and receive fluid from at least one end of the hollow center tube of the N hollow battery cells.

In other features, the enclosure has a cylindrical shape and the hollow center tube has a circular cross section.

In other features, the hollow center tube passes through the top surface and the bottom surface of the enclosure. The battery heat exchange system includes a second fluid channel configured to at least one of supply fluid to and receive fluid from an opposite end of the hollow center tube of the N hollow battery cells. At least one of the top surface and the bottom surface comprises a cap attached to the side walls of the enclosure and the hollow center tube.

In other features, the enclosure has a prismatic shape, and the hollow center tube has a rounded rectangular cross section. The hollow center tube passes through the top surface and the bottom surface of the enclosure. The battery heat exchange system includes a second fluid channel configured to at least one of supply fluid to and receive fluid from an opposite end of the hollow center tube of the N hollow battery cells. The first fluid channel includes a plurality of partitions to create a serpentine vertical path in the hollow center tube. The first fluid channel includes a plurality of partitions to create a serpentine horizontal path in the hollow center tube.

In other features, the N ports include N walls extending transverse to the first fluid channel and including threads on an outer surface thereof. An inner surface of the side wall of the hollow center tube of the N hollow battery cells includes threads. The first fluid channel includes N partitions in the N ports, respectively. Each of the N hollow battery cells includes a partition arranged in the hollow center tube. A second fluid channel is arranged adjacent and in contact with the first fluid channel, wherein fluid flows in a first direction through the first fluid channel and in a second direction through the second fluid channel. The first fluid channel extends in a serpentine path upwardly and downwardly through the hollow center tubes of adjacent ones of the N hollow battery cells.

In other features, the N ports include N walls extending transverse to the first fluid channel. The N walls are press fit into an inner surface of the side wall of the hollow center tube of the N hollow battery cells.

A battery system includes N hollow cylindrical battery cells, each including an enclosure including a top surface, a bottom surface, and side walls, a hollow center tube including a side wall defining a cavity and having a circular cross section, and a roll including electrode and separator layers arranged between an outer surface of the hollow center tube and the enclosure. The hollow center tube passes through at least one of the top surface and the bottom surface of the enclosure. A battery heat exchange system includes a first fluid channel including N ports configured to at least one of supply fluid to and receive fluid from at least one end of the hollow center tube of the N hollow cylindrical battery cells. The N ports include walls extending transverse to the first fluid channel and including threads on an outer surface thereof. An inner surface of the side wall of the hollow center tube of the N hollow cylindrical battery cells is threaded.

In other features, the hollow center tube passes through the top surface and the bottom surface of the enclosure. The battery heat exchange system includes a second fluid channel configured to at least one of supply fluid to and receive fluid from an opposite end of the hollow center tube of the N hollow cylindrical battery cells.

In other features, one of the first fluid channel includes N partitions in the N ports, respectively, and each of the N hollow cylindrical battery cells include a partition arranged in the hollow center tube.

A method for manufacturing a hollow battery cell includes double backwards extruding an enclosure for the hollow battery cell including a top surface, a side wall, a bottom surface, and a hollow center tube extending from the bottom surface and including a side wall and a cavity arranged between the side wall; winding a roll including electrode and separator layers; inserting the roll into the enclosure between the hollow center tube and the side wall of the enclosure; and attaching a top cap to the side wall and the hollow center tube on the top surface.

DETAILED DESCRIPTION

While hollow cylindrical and prismatic battery cells and heat exchange systems therefore are shown and described in the context of electric vehicles, the hollow cylindrical and prismatic battery cells and the heat exchange systems can be used in stationary applications and/or other applications.

Large format battery cells have high energy density and reduced manufacturing complexity/cost. However, as the size of the battery cells increase, it becomes more difficult to dissipate heat generated by the battery cells. When there is insufficient battery cooling, fast charging cannot be used with large format cells due to the high heat that is generated. While existing battery heat exchange systems can be used to heat and/or cool exposed surfaces of the battery cells (e.g., top, bottom and/or side surfaces of the battery cells), the center of the battery cell endures the highest temperatures during use.

The present disclosure relates to hollow battery cells including an outer enclosure and a hollow center tube. The outer enclosure can include a prismatic or cylindrical enclosure. In some examples, the hollow center tube has a circular cross section for cylindrical battery cells or a rounded rectangular cross section for prismatic battery cells. In some examples, the hollow center tube is arranged centrally relative to a center or center axis of the outer enclosure.

A roll of layers including one or more cathode electrodes, separators, and anode electrodes are wound around the hollow center tube. As will be described further below, a top cap and/or a bottom cap enclose the top and/or bottom sides of the battery cell.

The present disclosure also relates to a heat exchange system for hollow battery cells. The heat exchange system includes fluid channels and ports that fluidly connect and extend into the hollow center tubes from one or both sides to cool and/or heat the hollow battery cell from the center. In some examples, the fluid includes air, gas, and/or liquid. Cooling may be performed in response to cycling of the battery cells. Heating may be performed to heat a battery cell to a desired operating temperature after a soak at a lower temperature such as freezing or below.

Referring now toFIGS.1A to1C, an example of a cylindrical battery cell80that is not hollow is shown. InFIG.1A, the cylindrical battery cell80includes an outer enclosure82, a positive terminal84, and a negative terminal86. A center post88extends vertically along a central axis of the outer enclosure82. A roll89includes one or more anode electrodes, cathode electrodes, and separators wound around the center post88. Given the small radius of the center post88, there is a large bending force for thicker electrodes, which can make manufacturing difficult and/or reduce reliability.

InFIG.1B, the roll89of layers is shown to include a cathode electrode90, a separator92, an anode electrode94, and a separator96. In some examples, the positive terminal84may include vents or holes and a burst disk (not shown) to allow gas to vent when pressure inside the outer enclosure is greater than a predetermined pressure.

InFIG.1C, the cylindrical battery cell80may include a vent. For example, a positive terminal84may include one or more vent holes86. A burst disk88may be arranged below the positive terminal84. The burst disk88and the one or more vent holes86vent gas from the cylindrical battery cell80when pressure within the cylindrical battery cell80is greater than a predetermined pressure.

Referring now toFIGS.2A to2C, an example of a prismatic battery cell100is shown. InFIG.2A, a prismatic battery cell100includes an enclosure110. In some examples, the enclosure110has a rectangular cross-section. The prismatic battery cell100includes terminals114and116and a vent cap124. InFIG.2B, one or more rolls130-1and130-2including electrodes and separators are arranged side-by-side in the enclosure110. For example, the rolls130-1and130-2may include the electrode and separator layers shown inFIG.1B. The small winding diameter at ends of the rolls130-1and130-2requires a high bending force for thick electrodes, which can make manufacturing difficult and/or reduce reliability.

InFIG.2C, the terminal114and a tab135are connected to tab connectors136. The tab connectors136connect one polarity of the electrodes of the battery cell to the terminal114. In some examples, a seal134is arranged between the terminal114and the enclosure110.

Referring now toFIGS.3A to3E, an example of a hollow cylindrical battery cell200with a center hole that passes through a bottom surface of an outer enclosure is shown. InFIG.3A, the hollow cylindrical battery cell200includes an outer enclosure210, a positive terminal214(or terminal216), and a negative terminal216. A hollow center tube218including an outer cylindrical wall217and an inner cavity219extends vertically along a central axis of the outer enclosure210.

A roll220of layers is wound around the hollow center tube218. The roll220of layers includes one or more anode electrodes, cathode electrodes, and separators. InFIG.3B, the roll220is shown to include a cathode electrode230, a separator232, an anode electrode234, and a separator236. InFIG.3C, a top cap240of the hollow cylindrical battery cell is shown to include a center through hole242. InFIG.3D, the top cap240may include one or more vent holes243. A burst disk may be arranged below the top cap240as described above to vent gases when pressure within the cylindrical battery cell exceed a predetermined pressure. InFIG.3E, a bottom cap244of the hollow cylindrical battery cell is shown to include a center through hole246.

In some examples, the outer enclosure210has a height in a range from 60 mm to 120 mm (e.g., 80 mm or 100 mm). In some examples, the outer enclosure210has a diameter in a range from 40 mm to 60 mm (e.g., 46 mm).

Referring now toFIGS.4A to4C, an example of a hollow cylindrical battery cell250with a center through hole that does not pass through a bottom surface of an outer enclosure is shown. InFIG.4A, the hollow cylindrical battery cell250includes an outer enclosure260, a positive terminal264, and a negative terminal266. A hollow center tube268extends vertically along a central axis of the outer enclosure260. A bottom end of the hollow center tube268is closed. For example, the hollow center tube268may be welded to an inner side of a bottom surface of the outer enclosure260, insulated from the bottom surface of the outer enclosure260, and/or sealed as shown at270. A roll272includes one or more anode electrodes, cathode electrodes, and/or separators wound around the hollow center tube268.

InFIG.4B, the roll272is shown to include a cathode electrode280, a separator282, an anode electrode284, and a separator286that are wound around the hollow center tube268. InFIG.4C, a top cap290of the hollow cylindrical battery cell is shown to include a center through hole292.

Referring now toFIGS.5A to5C, an example of a hollow prismatic battery cell300with a center through hole that passes through a bottom surface of an outer enclosure is shown. InFIG.5A, the hollow prismatic battery cell300includes an enclosure310. In some examples, the enclosure310has a rectangular shape and includes a top side311, a bottom side313, and side walls315. The hollow prismatic battery cell300includes terminals312and314that are connected to the electrodes. The hollow prismatic battery cell300includes a hollow center tube318and a roll320including one or more electrodes and separators wound around the hollow center tube318.

InFIG.5B, the top side311of the hollow prismatic battery cell300is shown. In some examples, the hollow center tube318includes side walls341, a cavity343defined between the side walls341, an open top (FIG.5B), and an open bottom (FIG.5C). The hollow center tube318has a rounded rectangular cross section or an elongated elliptical cross section that extends in a vertical direction.

Referring now toFIGS.6A to6C, an example of a hollow prismatic battery cell350with a center through hole that does not pass through a bottom surface of an outer enclosure is shown. InFIG.6A, the hollow prismatic battery cell350includes an outer enclosure360. In some examples, the outer enclosure360has a rectangular shape and includes a top side361, a bottom side363, and side walls365. The hollow prismatic battery cell350includes terminals362and364connected to the electrodes. The hollow prismatic battery cell350includes a hollow center tube368and a roll370including one or more electrodes and separators wound around the hollow center tube368.

InFIG.6B, the top side361of the hollow prismatic battery cell350is shown. In some examples, the hollow center tube368includes walls371, a cavity373defined between the walls, an open top (FIG.6B), and a closed bottom (FIG.6C). The hollow center portion318has a rounded rectangular cross section or an elongated elliptical cross section that extends in a vertical direction.

Referring now toFIG.7, an example of a method400for manufacturing a hollow cylindrical battery cell is shown. At410, the outer enclosure of the battery cell is stamped or extruded with an open top and a closed bottom. At414, a hollow center tube is stamped or extruded.

At418, a hole is punched, drilled or laser cut in the bottom surface of the outer enclosure. At422, a roll of layers including one or more electrodes and separators are wound around the hollow center tube. At426, the hollow center tube and the roll of layers are inserted into the outer enclosure. In some examples, one or both ends of the hollow center tube extend beyond corresponding end(s) of the outer enclosure. In some examples, the hollow center tube passes through the hole in the bottom surface of the outer enclosure. In some examples, the hollow center tube passes through the hole in the top cap (when the top cap is arranged on the top side).

At430, the hollow center tube at the bottom of the outer enclosure is flanged outwardly to overlap edges of the hole in the bottom surface of the outer enclosure and the end of the hollow center tube is attached or sealed to the bottom surface. In other examples, a butt joint is created between the hollow center tube and the bottom surface. At434, a top cap is arranged over the top of the outer enclosure and is attached (e.g., laser welded or attached to the outer enclosure and the hollow center tube using another method) at438.

Referring now toFIG.8, a method500for manufacturing a hollow cylindrical battery cell is shown. At510, the outer enclosure of the battery cell is stamped or extruded with an open top and a closed bottom. At514, a hollow center tube is stamped or extruded with an open or closed bottom surface. At522, a roll of layers including electrodes and separators is wound around the hollow center tube.

At526, an inner enclosure (including the hollow center tube and the wound layers) are inserted into the outer enclosure. At530, the hollow center tube is attached (e.g., laser sealed) to an inner side of the bottom surface of the outer enclosure. At534, a hole is optionally punched, drilled or laser cut in the bottom surface and/or the center tube. At538, a top cap is attached (e.g., laser welded or attached using another method).

Referring now toFIGS.9A to9E, another method for manufacturing an outer enclosure including a center tube for a hollow cylindrical battery cell is shown. InFIG.9A, an extrusion tool550including a female tool552and a male tool554are forced together by a press or other device to extrude an outer enclosure551with a hollow center tube553. In some examples, double backward extrusion is performed with or without heating.

One or more additional forming steps may be performed as shown inFIGS.9B to9E. InFIG.9B, an ironing tool570may be used to improve the quality of the outer enclosure551and/or the hollow center tube553(e.g., by straightening side walls571). InFIG.9C, trimming of the outer enclosure551is optionally performed. InFIGS.9D and9E, a forming tool584is used to form steps or edges586on the outer enclosure551and/or the hollow center tube553to interface with and/or provide clearance for a top and/or bottom cap prior to attaching the top and/or bottom cap and prevent it from falling through.

In this example, the hollow battery cell enclosure is manufactured as a unibody component, which eliminates the need to weld the hollow center tube to the outer enclosure. Further processing allows steps and flanges to be formed for the top cap. The bottom of the hollow center tube can be left open for hollow battery cells with through holes. Alternately, the bottom of the hollow center tube can be covered for hollow battery cells with non-through holes.

Referring now toFIGS.10A to10D, assembly of the hollow cylindrical battery cell using the outer enclosure ofFIGS.9A to9Eis shown. InFIG.10A, a roll590including electrodes and separators is wound. InFIGS.10B and10C, the roll590of layers is inserted around the hollow center tube553in the outer enclosure551. A top cap592including a through hole594is attached (e.g., using welding, a butt joint, or other joining method) to enclose a top of the battery cell as shown inFIG.10D.

Referring now toFIG.11, a method650for manufacturing a cylindrical battery cell is shown. At660, the outer enclosure is extruded with an integrated hollow center tube. At664, ironing of the outer enclosure is optionally performed using an ironing tool to straighten sides walls of the outer enclosure. At668, trimming of the outer enclosure is optionally performed. At672, a roll electrode and separator layers is wound. At676, the roll is inserted in the outer enclosure between the hollow center tube and walls of the outer enclosure. At680, a top cap including a hole is arranged on the outer enclosure and attached at684(e.g., using welding, a butt joint, or other joining method) to enclose a top of the battery cell.

Referring now toFIGS.12A and12D, various examples of heat exchange systems for hollow cylindrical battery cells are shown. InFIG.12A, a heat exchange system720includes a first fluid channel724and a second fluid channel726that are in a heat exchange relationship with one another and/or with the atmosphere. In other words, outer surface areas of the first fluid channel724and the second fluid channel726are in contact with each other and/or air.

In some examples, liquid is supplied by a pump from a liquid source to the fluid channels to perform cooling. After passing through the fluid channels and absorbing heat, the liquid optionally passes through a heat exchanger such as a radiator with fins for cooling and then the liquid is returned to the source. In some examples, liquid is supplied by a pump from a liquid source to a heater and then to the fluid channels to perform heating. After passing through the fluid channels and supplying heat, the liquid is returned to the source.

The second fluid channel726includes ports730that extend transversely from the second fluid channel726and that are connected to hollow center tubes706of battery cells700. In some examples, the hollow center tubes706and the ports730include walls731with threaded portions at710and734, respectively. In other examples, the walls731of the ports730do not include threads and are press fit into the hollow center tubes706.

In some examples, the hollow center tubes706of the battery cells700are enclosed at702(at the bottom surface of the battery cells700). In some examples, the battery cells700include partitions708configured to partition the hollow center tubes706. In some examples, fluid740flows in the first fluid channel724in a first direction. Fluid742flows in the second fluid channel726in a second direction that is different than the first direction. Fluid742flows through the second fluid channel726, through the ports730, between the partition708and an inner surface of one side of the hollow center tube706of the battery cell700, around an end of the partition708, and between the partition708and an inner surface on the other side surface of the hollow center tube of the battery cell700back to the port730.

InFIG.12B, a heat exchange system750is similar to the heat exchange system720except that a partition752is connected to the heat exchange system750(e.g., at centers of the ports730) rather than in the hollow center tube706of the battery cells700.

InFIG.12C, a heat exchange system770is self-contained and does not incorporate the inner surfaces of the battery cells. The heat exchange system770includes side walls772enclosing distal ends of the ports730and a partition774connected transverse to the second fluid channel726. In some examples, the side walls772contact and form a tight fit with the walls of the hollow center tube706of the battery cells700to enhance heat exchange between the surfaces. In other examples, a thermal interface material or thermal adhesive (identified at777inFIG.12D) is arranged between the side walls772and the hollow center tube706.

In the examples inFIGS.12A to12C, the heat exchange systems contact top and/or bottom surfaces of the battery cells. InFIG.12D, a heat exchange system780may define a gap782between top surfaces of the battery cells700and the heat exchange system780. Since most of the cooling is performed along inner surfaces of the battery cells700, the gap782may be used.

Referring now toFIG.12E, a heat exchange system786is shown for an array787of the battery cells700. Manifolds788are arranged on opposite sides of the array787and channels789extend from side to side along each row between the manifolds788. As can be appreciated, the channels789can extend along columns of the array787. Connections to the positive or negative terminals of the battery cells can be made in off center locations.

Referring now toFIG.12F, a heat exchange system790is shown for the array787of the battery cells700. One or more fluid channels794extend in a zig-zag pattern each covering more than one row of the array787. As can be appreciated, other arrangements of the fluid channels can be used.

In some examples, the fluid channels of the heat exchange system are made of a material selected from a group consisting of aluminum alloy and copper. In some examples, the fluid comprises liquid, gas, or air. If the fluid channel includes multiple channels, a partition may be arranged in the fluid channel or the hollow center tube to divide the fluid channel. The partition can be made of a material selected from a group consisting of metal, polymer, and/or plastic. In some examples, the heat exchange system is self-enclosed. In other examples, the heat exchange system uses walls in the hollow center core and fluid directly contacts the walls of the hollow center core.

Referring now toFIGS.13A to13B, other examples of heat exchange systems for hollow prismatic battery cells are shown. InFIG.13A, heat exchange system810includes a fluid channel820that extends into a hollow center806of a prismatic battery cell800and around vertical partitions826and828to define a vertical zig-zag pattern830. InFIG.13B, heat exchange system838includes a fluid channel840that extends into a hollow center806of the prismatic battery cell800and around horizontal partitions842and one or more vertical partitions846to define a horizontal zig-zag pattern850.

Referring now toFIGS.14A to14C, for hollow battery cells with through holes, the fluid channels can be arranged on both sides of the battery cells. InFIG.14A, a heat exchange system900includes horizontal fluid channels920and930arranged on opposite sides of the battery cells700. Fluid924flows in the horizontal fluid channels920, through vertical channels926through the hollow center tube706of the battery cells700to the horizontal fluid channel930. In some examples, the horizontal fluid channels920and930flow in opposite directions.

InFIG.14B, a heat exchange system950includes horizontal fluid channels920and930arranged on opposite sides of the battery cells700. Vertical partitions952are arranged in the hollow center tube706of the battery cells700. The vertical partitions952extend into the horizontal fluid channels920and930and define a gap with an inner wall of the horizontal fluid channels920and930.

Fluid924flows in the horizontal fluid channels920, downwardly through vertical channels956on one side of the vertical partition952through the hollow center tube706of the battery cells700to the horizontal fluid channel930. The fluid924flows in the horizontal fluid channel930, upwardly through a vertical channel960on the other side of the vertical partition952through the hollow center tube706of the battery cells700to the horizontal fluid channel920. In some examples, the horizontal fluid channels920and930supply the fluid924in the same direction (e.g., from left to right inFIG.14B).

InFIG.14C, a heat exchange system970includes a fluid channel974(e.g., a single fluid channel) that extends through the hollow center tubes706of multiple adjacent battery cells700. In other words, the fluid channel974alternately extends upwardly through a hollow center tube of a first battery cell and across top surfaces of the first battery cell and a second battery cell, and then downwardly through the hollow center tube of the second battery cell and across a bottom surface of the second battery cell to another battery cell and so on. The battery cells can be arranged in a row or in rows and columns as shown inFIG.12F.