Battery unit, in particular for a watercraft, battery system, and watercraft

Abstract

The aim of the invention is to provide a battery unit, in particular for a watercraft, in which the battery cells provided in the battery unit are cooled in a thermally uniform way. This aim is achieved by a battery unit (100) comprising a housing (10) and at least one battery cell block (11a, 11b) that is located in the housing (10) and has at least one battery cell, wherein: the battery cell block (11a, 11b) comprises a sealed battery cell block housing (38); the at least one battery cell (12) is located in the battery cell block housing (38); the battery unit comprises at least one cooling channel (15, 15a, 15b) for air, which extends from a first side (13) of the housing (10) to a second side (14) of the housing (10) opposite the first side (13) and which has an inlet opening (16) located in the first side (13) and an outlet opening (17) located in the second side (14); the cooling channel (15, 15a, 15b) is arranged and designed for cooling the at least one battery cell (12) of the battery cell block (11a, 11b); the at least one cooling channel (15, 15a, 15b) has, along its extension between the inlet opening (16) and the outlet opening (17), at least one additional inlet opening (20) for the additional supply of air.

Description

[0001] Battery unit, in particular for a watercraft, battery system and watercraft

[0002] The present invention relates to a battery unit comprising a housing and at least one battery cell block arranged in the housing and having at least one battery cell, wherein the battery unit has at least one cooling channel for air extending from a first side of the housing to a second side of the housing opposite the first side, with an inlet opening arranged in the first side and an outlet opening arranged in the second side, wherein the cooling channel is arranged and configured to cool the at least one battery cell of the battery cell block.

[0003] Furthermore, the present invention relates to a battery system comprising a plurality of battery units and to a watercraft, in particular a ship, comprising a battery unit and / or a battery system.

[0004] Technological background

[0005] Batteries are used in many areas of technology. Especially for applications requiring high electrical power or high electrical currents, battery units are used, which comprise a large number of battery cells combined in battery cell blocks. One such application area is the maritime sector, where battery units are increasingly being used on ships.

[0006] The heat loss that occurs during operation of a battery unit can have a detrimental effect on the battery cells and, in particular, lead to premature aging of the battery cells. For this reason, cooling systems are provided in known battery units. The prior art uses air and water cooling systems in which air or water is guided past the battery cell blocks in cooling channels. Since the air or water continuously absorbs heat as it flows through the cooling channels, those battery cells in the battery cell blocks that are located at the end of the respective cooling channel can often only be insufficiently cooled. This results in an uneven temperature profile across the battery cell block, resulting in differential aging of the battery cells.

[0007] Description of the invention: task, solution, advantages

[0008] The present invention is based on the object of providing a battery unit, in particular for a watercraft, in which a thermally uniform cooling of the battery cells provided in the battery unit is achieved.

[0009] To achieve the object underlying the invention, a battery unit comprising a housing and at least one battery cell block arranged in the housing and having at least one battery cell is proposed, wherein the battery cell block comprises a closed battery cell block housing, wherein the at least one battery cell is arranged in the battery cell block housing, wherein the battery unit has at least one cooling channel for air extending from a first side of the housing to a second side of the housing opposite the first side, with an inlet opening arranged in the first side and an outlet opening arranged in the second side, wherein the cooling channel is arranged and configured to cool the at least one battery cell of the battery cell block, wherein it is further providedthat the at least one cooling channel has at least one secondary inlet opening for an additional supply of air along its extension between the inlet opening and the outlet opening.,

[0010] The battery unit can also be called a battery module.

[0011] The at least one battery cell can be designed as a block cell, in particular a substantially cuboidal one. Likewise, the at least one battery cell can also be designed as a round cell, in particular a substantially cylindrical one, or as a pouch cell. The battery unit is particularly suitable for use in the maritime sector, especially on ships such as ferries, cruise ships, yachts, tankers, or freighters.

[0012] The battery unit comprises a housing and a battery cell block arranged in the housing. The battery cell block comprises at least one battery cell. Preferably, the at least one battery cell block comprises a plurality of battery cells that are combined or integrated into the battery cell block.

[0013] Furthermore, at least one cooling channel for air is provided, which extends from a first side of the housing to a second side of the housing opposite the first side. The cooling channel is provided for cooling the at least one battery cell of the battery cell block. For this purpose, air enters the at least one cooling channel through the inlet opening provided in the first side of the housing. As it flows through the cooling channel, the air absorbs heat from the at least one battery cell of the battery cell block. The thus heated air then exits through the outlet opening in the second side of the housing.

[0014] According to the invention, it is provided that the at least one cooling channel has at least one secondary inlet opening for an additional supply of air along its extension between the inlet opening and the outlet opening.

[0015] In other words, in addition to the air entering the cooling channel through the inlet opening, air also enters the cooling channel through the at least one secondary inlet opening. Since the secondary inlet opening is arranged along the extension of the cooling channel between the inlet opening and the outlet opening, additional cool air is mixed with the air entering through the inlet opening as it progresses through the cooling channel, thereby increasing the cooling performance for the battery cells of the battery cell block arranged further back in the direction of air flow in the cooling channel, i.e. closer to the outlet opening. This makes it possible to achieve thermally uniform cooling of the battery cells provided in the battery unit. The additionally supplied air can also be referred to as secondary air or secondary air. Accordingly, the additional supply of air can be referred to as secondary air supply or secondary air supply.

[0016] It is preferably provided that the first side is a front side of the housing and that the second side is a rear side of the housing.

[0017] If the battery unit is cuboid-shaped, the front and rear sides are preferably flat or level. The front side can accommodate power connections as well as connections for digital communication and control of the battery unit.

[0018] It is preferably provided that the secondary inlet opening is arranged at a distance of between 25% and 75%, preferably between 40% and 60%, more preferably at 50%, of a length of the cooling channel from the inlet opening.

[0019] The cooling channel is particularly preferably designed to be straight and not meandering.

[0020] The length of the cooling channel essentially corresponds to the distance between the inlet opening and the outlet opening.

[0021] If only one secondary inlet opening is provided, it is advantageous if the secondary inlet opening is located approximately 50% of the length of the cooling channel from the inlet opening. Depending on the power output design of the battery unit, however, the secondary inlet opening can also be located closer to the inlet opening or closer to the outlet opening of the cooling channel.

[0022] It is advantageously provided that the cooling channel has several, preferably at least two, more preferably at least three, secondary inlet openings, which are arranged at different distances from the inlet opening.

[0023] By providing multiple secondary inlet openings, additional air can be introduced into the cooling channel at various locations along the length of the cooling channel. For example, the cooling channel can have two secondary inlet openings, in which case it may also be preferable for the first secondary inlet opening to be located at a distance of approximately 30% of the length of the cooling channel from the inlet opening, and for the second secondary inlet opening to be located at a distance of approximately 60% of the length of the cooling channel from the inlet opening.

[0024] Preferably, each of the plurality of secondary inlet openings has a flow cross-section, wherein the flow cross-sections of the secondary inlet openings decrease with the distance of the respective secondary inlet opening from the inlet opening.

[0025] The flow cross-section refers, in particular, to the area of ​​the secondary inlet opening through which the additional air flows. It is particularly advantageous if the secondary inlet openings located closer to the inlet opening of the cooling channel have a larger flow cross-section than the secondary inlet openings located farther away from the inlet opening.

[0026] It is preferably provided that the battery cell block is cuboid-shaped, wherein the battery cell block preferably has a front wall, a rear wall and four side walls.

[0027] The battery cell block comprises a, in particular hermetically sealed, battery cell block housing in which the at least one battery cell is located or the battery cells are arranged. It is particularly advantageous if the battery cell block is cuboid-shaped, as it can then be easily integrated into the housing of the battery unit.

[0028] Particularly when the battery unit is used in maritime applications, there is a risk of corrosion or contamination of the battery cells. Therefore, the housing, which is in particular hermetically sealed, is preferably waterproof and / or dustproof and / or airtight. The battery cell block housing is preferably sealed at least according to protection class IP44, more preferably at least according to IP67. Advantageously, it can be provided that the battery cell block extends in a direction of extension between the first side and the second side of the housing, wherein the at least one cooling channel adjoins a side wall of the battery cell block running parallel to the direction of extension and / or is in thermal contact with a side wall of the battery cell block running parallel to the direction of extension.

[0029] Preferably, the at least one cooling channel extends outside the battery cell block housing. If multiple cooling channels and multiple battery cell blocks are provided, all cooling channels preferably extend outside the battery cell block housings of the battery cell blocks.

[0030] In particular, no air is passed through the battery cell block or the battery cell block housing to cool the at least one battery cell. Thus, the air used to cool the battery cells neither enters the battery cell block or the battery cell block housing, nor does it exit the battery cell block or the battery cell block housing. The battery cells are cooled by heat transfer from the battery cells to the battery cell block housing, and from the battery cell block housing to the cooling channel or to the air flowing through the cooling channel.

[0031] If necessary, a thermal contact material having a high thermal conductivity can be arranged in the battery cell block housing in order to increase the heat transfer from the battery cells to the battery cell block housing.

[0032] The direction of extension of the battery cell block preferably runs along its largest dimension. In particular, the direction of extension runs from the front wall to the rear wall of the battery cell block. Four side walls of the battery cell block are then arranged parallel to the direction of extension. The battery cell block is arranged between the first side and the second side of the housing. However, this does not necessarily mean that the battery cell block, in particular its front wall and rear wall, is in direct contact with the first side and the second side of the housing.

[0033] The cooling channel is adjacent to one of the side walls of the battery cell block that runs parallel to the direction of extension or is in thermal contact with such a side wall. This means that the air flows through the cooling channel adjacent to the side wall or is in thermal contact with the side wall, thus being able to absorb sufficient heat from the battery cells of the battery cell block.

[0034] It is preferably provided that the secondary inlet opening, more preferably the plurality of secondary inlet openings, is arranged in an outer wall of the housing.

[0035] In other words, in this case, the cooling channel runs between the battery cell block and the outer wall of the housing, whereby the side wall of the battery cell block can form part of the wall of the cooling channel, and whereby the outer wall of the housing can form another part of the wall of the cooling channel. The arrangement of at least one secondary inlet opening in the outer wall of the housing allows additional air to flow unhindered into the cooling channel.

[0036] Preferably, a plurality of cooling channels are provided, wherein each cooling channel is adjacent to a respective side wall of the battery cell block running parallel to the direction of extension and / or is in thermal contact with each side wall of the battery cell block running parallel to the direction of extension.

[0037] The battery cell block can thus be cooled by arranging a plurality of cooling channels on a plurality of sides, in particular on a plurality of side walls. In particular, it can be provided that two, three or four cooling channels are provided, wherein the cooling channels accordingly border one, two, three or four side walls of the battery cell block or are in thermal contact with one, two, three or four side walls of the battery cell block. It is further advantageously provided that at least two battery cell blocks are arranged adjacent to one another in the housing, wherein each of the battery cell blocks has at least one cooling channel bordering a side wall of the respective battery cell block and / or being in thermal contact with a side wall of the battery cell block.

[0038] The at least two battery cell blocks are preferably designed similarly or largely identically, i.e., each battery cell block is adjoined by at least one cooling channel which is configured and arranged to cool the battery cells of the battery cell block.

[0039] The battery cell blocks are arranged in the housing, in particular adjacent to one another. Each of the battery cell blocks has at least one side wall facing the adjacent battery cell block.

[0040] It is preferably provided that each of the battery cell blocks has a cooling channel adjacent to a side wall facing an adjacently arranged battery cell block, wherein a secondary air channel runs between the cooling channels of the adjacently arranged battery cell blocks adjacent to the side walls, wherein the secondary inlet openings of the cooling channels are open into the secondary air channel.

[0041] The inlet openings of these cooling channels, which are adjacent to the mutually facing side walls of the adjacently arranged battery cell blocks, as well as a secondary air inlet opening of the secondary air channel, are preferably located approximately centrally on the first side of the battery unit housing. Correspondingly, the outlet openings of the cooling channels, which are adjacent to the mutually facing side walls of the adjacently arranged battery cell blocks, are preferably located approximately centrally on the second side of the battery unit housing. The secondary air channel runs parallel to and between the cooling channels and preferably also extends from the first side of the housing to the second side of the housing opposite the first side. The cooling channels, which are arranged on the side walls of the at least two battery cell blocks facing the respective other battery cell block, thus run parallel and adjacent to one another.In order to also enable the supply of additional air, in particular secondary air, to these cooling channels, which essentially run inside the battery unit, a secondary air channel is provided between these adjacent cooling channels, and the secondary inlet openings of the two cooling channels open into this secondary air channel. For this purpose, the secondary air channel preferably also has a secondary air inlet opening in the first side of the battery unit housing.

[0042] Air enters these cooling channels through the inlet openings of the cooling channels located approximately centrally on the first side of the battery unit housing, which are located on the facing side walls of the adjacent battery cell blocks. At the same time, air enters through the secondary air inlet opening of the secondary air duct located between these two cooling channels. The secondary inlet openings of the cooling channels are open in this secondary air duct, meaning that air from the secondary air duct can flow into the cooling channels of the adjacent battery cell blocks through the respective secondary inlet openings, thus ensuring sufficient and uniform cooling of the battery cells of the adjacent battery cell blocks.

[0043] It is advantageously provided that cooling elements, in particular cooling fins, are arranged in the at least one cooling channel.

[0044] The cooling elements can increase the cooling performance.

[0045] In this case, it can advantageously be provided that the at least one cooling channel has a wall, wherein the wall is formed at least partially by the side wall of the battery cell block and a housing wall of the housing. The side wall of the battery cell block can also be a lower side wall.

[0046] In other words, the at least one cooling channel can thus be arranged directly on the battery cell block and formed at least partially by the side wall of the battery cell block. Advantageously, the cooling elements are arranged on the side wall of the battery cell block. The housing wall, which forms part of the wall of the cooling channel, can be a cover plate attached to the housing.

[0047] It is preferably provided that the battery unit has at least one, preferably at least two, fans, wherein the fan is arranged on the second side of the housing, and wherein the fan is designed to suck air out of the at least one cooling channel.

[0048] At least one fan draws air out of the cooling channel, creating a negative pressure in the cooling channel. This negative pressure causes additional air to be drawn in through the cooling channel's secondary inlet.

[0049] It is advantageous to provide a fan for each battery cell block.

[0050] The fan can preferably be an axial fan, a radial fan or a tangential fan.

[0051] In a preferred embodiment, it is provided that a cover hood, preferably made of a plastic, is arranged on the second side, wherein at least one air chamber is formed between the cover hood and the second side, and wherein the outlet opening of the at least one cooling channel opens into the at least one air chamber.

[0052] In other words, the air exiting the outlet opening of the cooling channel enters the air chamber between the cover and the second side of the housing and not directly into the environment. The air chamber preferably has an air outlet opening through which the air entering the air chamber from the cooling channel can flow out of the air chamber. It can be provided that the at least one fan is fastened in or on the cover. Preferably, the at least one fan is arranged at the air outlet opening of the air chamber. Several air chambers can also be formed between the cover and the second side, wherein one air chamber is assigned to each cooling channel of a battery cell block, i.e. the outlet openings of some, preferably all, cooling channels adjacent to the side walls of a battery cell block open into the same one of the several air chambers.

[0053] Preferably, the battery cells are lithium iron phosphate batteries (LFP batteries). In principle, the battery cells can also be based on other technologies.

[0054] It is further advantageous that the battery unit has a C-rate of 0.5 to 0.7, preferably 0.6, and / or that the battery unit has a peak C-rate of 0.8 to 2.0, preferably 1.0 to 1.5.

[0055] The C-rate indicates the time within which the battery unit can be fully discharged. A C-rate of 1 means the battery can be discharged within one hour. A C-rate of 2 means the battery can be discharged within half an hour, and a C-rate of 0.5 means the battery can be discharged within two hours.

[0056] A distinction must be made between an average C-rate, i.e., a C-rate during continuous operation, where the battery is continuously fully charged and discharged, and a peak C-rate. The average C-rate for the battery unit is preferably 0.5 to 0.7, and particularly preferably 0.6. The peak C-rate indicates the time for a single discharge process at maximum power during discontinuous operation. The peak C-rate for the battery unit is preferably between 0.8 and 2.0, in particular between 1.0 and 1.5.

[0057] The energy density of the battery unit, in particular of the battery cell, is preferably between 100 Wh / kg and 180 Wh / kg, particularly preferably between 130 Wh / kg and 150 Wh / kg.

[0058] The capacity of the battery unit is preferably between 10 kWh and 15 kWh, particularly preferably between 12 kWh and 13 kWh. The electrical voltage delivered by the battery unit, particularly the direct voltage, is preferably at least 50 V, more preferably at least 60 V.

[0059] Preferably, the electrical voltage delivered by the battery unit, in particular the direct voltage, is a maximum of 100 V, more preferably a maximum of 90 V.

[0060] A further solution to the problem underlying the invention consists in a battery system comprising several battery units as described above.

[0061] In this case, it can preferably be provided that the battery system has a holding device, wherein the battery units are arranged in the holding device. The holding device can preferably be a rack, a frame, a rack, or a cabinet.

[0062] The battery units can also be attached to each other.

[0063] It can be provided that the holding device comprises a fan.

[0064] Fans can therefore be provided in the mounting device, particularly in the rack, frame, stand, or cabinet. If fans are provided in the mounting device, the fans for the individual battery units may be omitted. In this case, a cover for the battery units may also be omitted.

[0065] A further solution to the problem underlying the invention consists in a watercraft, in particular a ship or a ferry, comprising a battery unit as described above or comprising a battery system as described above.

[0066] Short description of the characters

[0067] The invention is explained in more detail below with reference to the accompanying figures. Fig. 1 shows an isometric view of a battery unit,

[0068] Fig. 2 a front view of the battery unit,

[0069] Fig. 3 a rear view of the battery unit,

[0070] Fig. 4 a side view of the battery unit,

[0071] Fig. 5 a bottom view of the battery unit,

[0072] Fig. 6 a horizontal longitudinal section through the battery unit,

[0073] Fig. 7 a battery system comprising battery units,

[0074] Fig. 8 a watercraft with a battery system, and

[0075] Fig. 9 a battery cell block.

[0076] Detailed description of the characters

[0077] In the figures, identical or corresponding parts are identified by the same reference numerals.

[0078] Fig. 1 shows an isometric view of a battery pack 100 in accordance with the invention. Fig. 2 shows a front view of the battery pack 100. Fig. 3 shows a rear view of the battery pack 100. Fig. 4 shows a side view and Fig. 5 shows a bottom view of the battery pack 100. Fig. 6 shows a horizontal longitudinal section of the battery pack 100.

[0079] The battery unit 100 has a housing 10. According to Fig. 6, two battery cell blocks 11a, 11b are arranged adjacent to one another in the housing 10, each of the battery cell blocks 11a, 11b comprising a plurality of battery cells 12. The housing 10 of the battery unit 100 has a first side 13 and a second side 14 opposite the first side 13. The first side 13 is the front side 13a of the housing 10. The second side 14 is the rear side 14a of the housing 10.

[0080] A plurality of cooling channels 15, 15a, 15b extend between the first side 13 and the second side 14 of the housing 10. Each of the cooling channels 15, 15a, 15b has an inlet opening 16 arranged in the first side 13 and an outlet opening 17 arranged in the second side 14 of the housing 10. As can be seen in particular from Figs. 1 and 2, cooling channels 15a are provided in the region of the outer sides 18 and the underside 19 of the battery unit 100. In addition, two central cooling channels 15b are provided, running approximately centrally through the housing 10. The cooling channels 15b running centrally through the housing 10 also run between the two battery cell blocks 11a, 11b (Fig. 6). The cooling channels 15, 15a, 15b are arranged and configured to cool the battery cells 12 of the battery cell blocks 11a, 11b.For this purpose, air flows through the respective inlet opening 16 into the individual cooling channels 15, 15a, 15b and is guided along the battery cell blocks 11a, 11b, whereby the air absorbs heat from the battery cells 12. The thus heated air then exits through the outlet openings 17 of the cooling channels 15, 15a, 15b.

[0081] Each of the cooling channels 15, 15a, 15b has a secondary inlet opening 20 for an additional supply of air. In the side view according to Fig. 4, the bottom view according to Fig. 5, and the sectional view according to Fig. 6, it can be seen that the corresponding secondary inlet openings 20 of the cooling channels 15, 15a, 15b are located at a distance of approximately 50% of the length of the respective cooling channel 15, 15a, 15b from the inlet opening 16.

[0082] Additional air can enter the cooling channels 15, 15a, 15b through the secondary inlet openings 20, whereby cool air is added to the air that entered through the inlet openings 16 and was temporarily heated on its way through the cooling channels 15, 15a, 15b.

[0083] A cover 21, preferably made of plastic, is arranged on the second side 14 of the housing 10 of the battery unit 100. An air chamber 30, into which the cooling channels 15, 15a, 15b open, is formed between the cover 21 and the second side 14. Fans 22, which are designed as axial fans 23, are arranged on the cover 21. Operation of the fans 22 creates a negative pressure in the cooling channels 15, 15a, 15b, which causes air to be drawn into the respective cooling channels 15, 15a, 15b through the respective inlet openings 16 and through the secondary inlet openings 20. Referring to Fig. 6, the two battery cell blocks 11a, 11b arranged within the housing 10 are approximately cuboid-shaped and have a front wall 24, a rear wall 25 and side walls 26, 26a, which run parallel to an extension direction TI of the battery cell blocks 11a, 11b.Each of the central cooling channels 15b, which run approximately centrally through the housing 10, borders the side walls 26a of the battery cell blocks 11a, 11b facing the other battery cell block 11a, 11b. A secondary air channel 28 is provided between these two cooling channels 15b, which also runs from the first side 13 to the second side of the housing 14. The secondary inlet openings 20 of the centrally arranged cooling channels 15b open into the secondary air channel 28, so that an additional supply of air is also possible for these cooling channels 15b. The secondary air channel 28 has a secondary air inlet opening 29 in the first side 13 of the housing 10.

[0084] The front view according to Fig. 2 shows that cooling elements 31 in the form of cooling fins 32 are located in the cooling channels 15, 15a, 15b. The cooling elements 31 are arranged on the side walls 26, 26a of the battery cell blocks 11a, 11b. To form the cooling channels 15a arranged in the region of the outer sides 18 and the underside 19, cover plates 33 are placed on the cooling elements 31. The walls of the cooling channels 15a are thus formed at least partially from the cover plates 33 of the housing 10 and the side walls 26 of the battery cell blocks 11a, 11b.

[0085] On the first side 13 of the housing 10 of the battery unit 100, electrical power connections 34 and connections 35 for digital communication and control of the battery unit 100 are provided.

[0086] Fig. 7 shows a battery system 200 in accordance with the invention. The battery system 200 has a holding device 36 in the form of a rack 37 in which several battery units 100 are arranged.

[0087] Fig. 8 shows a watercraft 300 comprising a battery system 200 having a plurality of battery units 100. Fig. 9 shows one of the battery cell blocks 11a, 11b of the battery unit 100 according to Fig. 6. The battery cell block 11a, 11b has a, in particular hermetically sealed, battery cell block housing 38 in which the battery cells 12 are arranged. The battery cells 12 can be configured as block cells, essentially cuboidal, as shown. In principle, the battery cells 12 can also be configured as cylindrical round cells or as pouch cells.

[0088] List of reference symbols

[0089] 100 battery units

[0090] 200 battery system

[0091] 300 watercraft

[0092] 10 housings

[0093] 11a Battery cell block

[0094] 11b Battery cell block

[0095] 12 battery cells

[0096] 13 First page

[0097] 13a front

[0098] 14 Second page

[0099] 14a back

[0100] 15 Cooling channel

[0101] 15a Cooling channel

[0102] 15b Cooling channel

[0103] 16 Entrance opening

[0104] 17 Exit opening

[0105] 18 Outside

[0106] 19 Bottom

[0107] 20 secondary entrance opening

[0108] 21 Cover

[0109] 22 fans

[0110] 23 axial fans

[0111] 24 front wall

[0112] 25 Rear wall

[0113] 26 Side wall

[0114] 26a side wall

[0115] TI extension direction

[0116] 28 secondary air duct

[0117] 29 Secondary air inlet opening Air chamber Cooling element Cooling fin Cover plate Power connection Connection Holding device Rack Battery cell block housing

Claims

Claims 1. Battery unit (100) comprising a housing (10) and at least one battery cell block (11a, 11b) arranged in the housing (10) and having at least one battery cell (12), wherein the battery cell block (11a, 11b) comprises a closed battery cell block housing (38), wherein the at least one battery cell (12) is arranged in the battery cell block housing (38), wherein the battery unit has at least one cooling channel (15, 15a, 15b) for air extending from a first side (13) of the housing (10) to a second side (14) of the housing (10) opposite the first side (13), with an inlet opening (16) arranged in the first side (13) and an outlet opening (17) arranged in the second side (14), wherein the cooling channel (15, 15a, 15b) for cooling the at least one battery cell (12) of the Battery cell block (11a, 11b) is arranged and arranged, characterized in that the at least one cooling channel (15, 15a,15b) along the extension of which, between the inlet opening (16) and the outlet opening (17), at least one secondary inlet opening (20) for an additional supply of air.

2. Battery unit (100) according to claim 1, characterized in that the first side (13) is a front side (13a) of the housing (10) and that the second side (14) is a rear side (14a) of the housing (10).

3. Battery unit (100) according to claim 1 or 2, characterized in that the secondary inlet opening (20) is arranged at a distance between 25% and 75%, preferably between 40% and 60%, more preferably at 50%, of a length of the cooling channel (15, 15a, 15b) from the inlet opening (16).

4. Battery unit (100) according to one of the preceding claims, characterized in that the cooling channel (15, 15a, 15b) has a plurality of, preferably at least two, more preferably at least three, secondary inlet openings (20) which are arranged at different distances from the inlet opening (16).

5. Battery unit (100) according to claim 4, characterized in that each of the plurality of secondary inlet openings (20) has a flow cross-section, wherein the flow cross-sections of the secondary inlet openings (20) decrease with the distance of the respective secondary inlet opening (20) from the inlet opening (16).

6. Battery unit (100) according to one of the preceding claims, characterized in that the battery cell block (11a, 11b) is cuboid-shaped, wherein the battery cell block (11a, 11b) preferably has a front wall (24), a rear wall (25) and four side walls (26, 26a).

7. Battery unit (100) according to one of the preceding claims, characterized in that the battery cell block (11a, 11b) extends in an extension direction (27) between the first side (13) and the second side (14) of the housing (10), wherein the at least one cooling channel (15, 15a, 15b) adjoins a side wall (26, 26a) of the battery cell block (11a, 11b) running parallel to the extension direction (27), and / or is in thermal contact with a side wall (26, 26a) of the battery cell block (11a, 11b) running parallel to the extension direction (27).

8. Battery unit (100) according to one of the preceding claims, characterized in that the secondary inlet opening (20), preferably the plurality of secondary inlet openings (20), is arranged in an outer wall of the housing (10).

9. Battery unit (100) according to claim 7 or 8, characterized in that a plurality of cooling channels (15, 15a, 15b) are provided, wherein one cooling channel (15, 15a, 15b) is adjacent to a respective side wall (26, 26a) of the battery cell block (11a, 11b) running parallel to the direction of extension (27), and / or is in thermal contact with one respective side wall (26, 26a) of the battery cell block (11a, 11b) running parallel to the direction of extension (27).

10. Battery unit (100) according to one of the preceding claims, characterized in that in the housing (10) at least two battery cell blocks (11a, 11b) are arranged adjacent to one another, wherein each of the battery cell blocks (11a, 11b) has at least one cooling channel (15, 15a, 15b) adjacent to a side wall (26, 26a) of the respective battery cell block (11a, 11b) and / or in thermal contact with a side wall (26, 26a) of the battery cell block (11a, 11b).

11. Battery unit (100) according to claim 10, characterized in that each of the battery cell blocks (11a, 11b) has a cooling channel (15b) adjacent to a side wall (26a) facing an adjacently arranged battery cell block (11a, 11b), wherein a secondary air channel (28) runs between the cooling channels (15b) of the adjacently arranged battery cell blocks (11a, 11b) adjacent to the side walls (26a), wherein the secondary inlet openings (20) of the cooling channels (15b) are open into the secondary air channel (28).

12. Battery unit (100) according to one of the preceding claims, characterized in that cooling elements (31), in particular cooling fins (32), are arranged in the at least one cooling channel (15, 15a, 15b).

13. Battery unit (100) according to one of claims 7 to 12, characterized in that the at least one cooling channel (15, 15a, 15b) has a wall, wherein the wall is formed at least partially by the side wall (26) of the battery cell block (11a, 11b) and a housing wall of the housing (10).

14. Battery unit (100) according to claim 12 or 13, characterized in that the cooling elements (31) are arranged on the side wall (26) of the battery cell block (11a, 11b).

15. Battery unit (100) according to claim 13 or 14, characterized in that the housing wall is a cover plate (33) fastened to the housing (10).

16. Battery unit (100) according to one of the preceding claims, characterized in that the battery unit has at least one, preferably at least at least two fans (22), wherein the fan (22) is arranged on the second side (14) of the housing (10), and wherein the fan (22) is designed to suck air out of the at least one cooling channel (15, 15a, 15b).

17. Battery unit (100) according to claim 16, characterized in that the fan (22) is an axial fan (23) or a radial fan or a tangential fan.

18. Battery unit (100) according to one of the preceding claims, characterized in that a cover (21), preferably made of a plastic, is arranged on the second side (14), wherein at least one air chamber (30) is formed between the cover (21) and the second side (14), and wherein the outlet opening (17) of the at least one cooling channel (15, 15a, 15b) opens into the at least one air chamber (30).

19. Battery unit (100) according to one of the preceding claims, characterized in that the battery cells (12) are lithium iron phosphate accumulators.

20. Battery unit (100) according to one of the preceding claims, characterized in that the battery unit has a C-rate of 0.5 to 0.7, preferably of 0.6, and / or that the battery unit (100) has a peak C-rate of 0.8 to 2.0, preferably of 1.0 to 1.

5.

21. Battery system (200) comprising a plurality of battery units (100) according to one of the preceding claims.

22. Battery system (200) according to claim 21, comprising a holding device (36), wherein the battery units (100) are arranged in the holding device (36).

23. Battery system according to claim 22, characterized in that the holding device (36) is a rack (37), a frame, a rack or a cabinet.

24. Battery system according to claim 22 or 23, characterized in that the holding device (36) comprises a fan.

25. Watercraft (300), in particular a ship, comprising a battery unit (100) according to one of claims 1 to 20 and / or comprising a battery system (200) according to one of claims 21 to 24.

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