A battery module, a battery pack and a method for controlling temperature inside a battery pack

Abstract

A battery module (10) comprising: a plurality of battery cells (20), wherein each of the battery cells (20) comprises a first surface (21) which comprises a positive cell terminal (22A) and a negative cell terminal (22B), wherein the battery cells (20) are arranged in a battery cell stack (31) extending in a first direction (D1), wherein the first direction (D1) is perpendicular to a contact surface (CS) between two adjacent battery cells (20), wherein all the battery cells (20) of the battery cell stack (31) are oriented in a second direction (D2), wherein the second direction (D2) is perpendicular to the first direction (D1) and is also perpendicular to the first surfaces (21) of the battery cells (20), wherein the battery cell stack (31) has a third direction (D3), wherein the third direction is perpendicular to the first direction (D1) and the second direction (D2); a strapping device (40), wherein the strapping device (40) extends at least in the first direction (D1) such as to compress the battery cells (20) towards each other; an outer containment (50), wherein the outer containment (50) encloses the battery module (10).

Description

[0001] TITLE: A BATTERY MODULE, A BATTERY PACK AND A METHOD FOR CONTROLLING TEMPERATURE INSIDE A BATTERY PACK

[0002] TECHNICAL FIELD

[0003] The present invention relates to a battery module, a battery pack and a system for providing electric energy to a vessel. The present invention also relates to a method for controlling temperature inside a battery pack.

[0004] BACKGROUND

[0005] Electric energy storage assemblies, sometimes referred to as battery blocks, battery modules, strings of battery modules, battery packs, battery assemblies or similar, are considered as one of the preferred options for a sustainable energy source in marine structures.

[0006] The primary technical showstopper for widespread application of electric ships or vessels is pointed out to be high complexity and cost, low energy density, limited suitability and safety in a marine environment of prior art electric energy storage systems.

[0007] Prior art marine electric energy storage assemblies are designed for peak shaving, i.e. for allowing internal combustion engines to operate at optimal loads where specific fuel consumption is low. Such assemblies are characterized by a high C- rate, where the C-rate is a measure of the rate at which a battery is discharged or charged relative to its maximum capacity. Each cell in the assembly can provide high power outputs (P) and / or current in relation to its energy carrying capacity (E). Typical C-rates for prior art electric energy storage assemblies are in the range of P / E equalling from 0.5C to 3C.

[0008] Electric energy storage assemblies with a high C-rate typically generate a high amount of heat, causing strict requirements for cooling and temperature control of the battery cells of the electric energy storage assemblies in order to counteract or limit rise of cell temperatures during use, and thus in turn for limiting performance degradation or exitance of acceptable safe temperatures. High temperatures may also cause an increased risk of thermal runaway events and consequentially result in safety problems and / or concerns that in some cases may be ventilation of hazardous gases, fire and / or cell explosion.

[0009] When a cell in a prior art module, enters a gas-off state, normally leading to a thermal runaway event, module containments or encapsulation are filled with explosive and flammable gas. Off-gas is then getting in contact with all cells within the module and electric conductors / spark sources, leading to a risk for ignition and fire to commence inside the battery module. This may and have caused severe damage and safety consequences in prior art systems.

[0010] To limit high temperatures inside current state of the art battery modules, modules are either fitted with a cooling fan or internal liquid cooling coils.

[0011] The energy consumption for cooling demands may in some cases constitute as much as 10-30% of the assembly’s energy carrying capacity depending on operation profile and C-rate requirement.

[0012] When fitted with a fan, temperature control of the cells is done by creating forced convection heat transfer between the battery cells and the surroundings, where the surroundings are fitted with an air-to-air heat exchange system. Such architecture has proven to increase the risk for humidity and dust to enter the module, creating corrosion and or deteriorating sensitive electronics inside the module causing technical and / or safety issues.

[0013] When fitted with internal cooling coils, temperature control of cells is done by creating natural convection between cells and the coils, where coils include circulating liquid coolant heat exchanged with the surroundings normally in an air to liquid heat exchange process. Such cooling method has, like forced air convection systems, also low efficiency, and has proven to create a risk for liquid leakage inside the modules creating a risk for short circuit when a cell or several cells are immersed in coolant liquid.

[0014] Both methods require space, leading to decreased energy density. And both options may lead to potential technical and / or safety issues.

[0015] Prior art battery modules are often designed such that they accept the propagation of a thermal runaway event between individual cells in a block or a module.

[0016] Propagation between modules in an electric energy storage system of multiple modules is commonly stopped by means of cooling of battery modules with freshwater mist sprinklers or nozzles directed towards horizontally positioned modules requiring void spaces above and / or below modules to achieve a homogeneous module surface temperature, due to module orientation.

[0017] In prior art modules where propagation of thermal runaway events between cells is not allowed, cooling fans or coils is typically taking up lots of space to achieve satisfactory cooling between cells preventing temperature of adjacent cells to reach certain onset / threshold temperature resulting in propagation. In some cases thermal insulation is fitted between cells to limit heat transfer between cells, also requiring space lowering energy density and increasing complexity. Prior art system does not cool individual cells from inside during a thermal runaway event. Void spaces, a consequence of both prior art methods for temperature control, have an impact on volume efficiency and energy density. The void spaces may also have negative impact on sensitive electronics inside modules, including printed circuit boards and sensor(s), when the modules are exposed to temperature fluctuations causing water condensation and ultimately corrosion and performance degradation of electronics inside the module. Dust accumulation inside the void spaces in the modules, may also cause deterioration of the electronics and act as thermal insulation affecting cooling performance.

[0018] Prior art marine electric energy storage assemblies often consist of cells assembled in modules positioned in a structurally reinforced steel structure, known as a module assembly encapsulation, whereas each individual cell within the encapsulation is mechanically fixated in the encapsulation such that bodily movements of the cells within the encapsulation are prevented. To facilitate fixation of the cells, the encapsulation is structurally reinforced so that it can be supported in a shelf structure where the modules act as a drawer in a drawer section / shelf.

[0019] Prior art modules in electric energy storage assemblies utilize reinforced encapsulation to limit and / or avoid loads to act on cells within the encapsulation that may stress the battery cells in such manner that the cells become damaged. To fixate cells and to limit and / or avoid loads to act on cells, the module encapsulation is constructed with a skeleton of structurally reinforced steel members or steel profiles, that creates void spaces and adds weight and complexity to the system.

[0020] Prior art modules have a cell orientation where cell poles (positive and negative) and gas off from a cell is directed vertically upward. Thus, compression force created by the weight of adjacent cells exposed to vibration loads and any other static and dynamic load on board a marine structure is absent. Compression force is only created from steel belts and not gravitational loads from cells lying above each cell.

[0021] It is an aim of the present disclosure to provide an electric energy storage assembly and system for marine vessels with increased energy density, safety and more minimalistic and cost-effective design relative to prior art electric energy storage assemblies and systems.

[0022] SUMMARY OF THE INVENTION

[0023] The present invention is directed to a solution that may solve or at least reduce at least one of the aforementioned problems or challenges.

[0024] The invention is defined in the attached claims. It is defined a battery module comprising:

[0025] - a plurality of battery cells, wherein each of the battery cells comprises a first surface which comprises a positive cell terminal and a negative cell terminal, wherein the battery cells are arranged in a battery cell stack extending in a first direction, wherein the first direction is perpendicular to a contact surface between two adjacent battery cells, wherein all the battery cells of the battery cell stack are oriented in a second direction, wherein the second direction is perpendicular to the first direction and is also perpendicular to the first surfaces of the battery cells, wherein the battery cell stack has a third direction, wherein the third direction is perpendicular to the first direction and the second direction;

[0026] - a strapping device, wherein the strapping device extends at least in the first direction such as to compress the battery cells towards each other;

[0027] - an outer containment, wherein the outer containment encloses the battery module.

[0028] The first surface of the battery cell may comprise a ventilation port.

[0029] The battery cells may be arranged in a battery cell stack extending in a positive or negative first direction.

[0030] The first direction may be a vertical direction.

[0031] The first positive direction may be upwards.

[0032] The battery cells of the battery cell stack may be oriented in a positive or negative second direction.

[0033] The battery cell stack may comprise 15 battery cells arranged in the first direction.

[0034] The battery cell stack may comprise 16 battery cells arranged in the first direction.

[0035] The battery cells may be prismatic battery cells.

[0036] The battery cells may be battery cells protected against fire and explosion during a thermal runaway.

[0037] The thickness of the outer containment may be in the range of 1 to 30mm.

[0038] The outer containment may be reinforced by fibres and / or fabrics. Two or more batery cell stacks may be arranged side by side in the third direction, wherein all normal directions of the first surfaces of each battery cell stack may be parallel with the second direction.

[0039] Battery cell stacks may be arranged side by side in the positive or negative third direction.

[0040] Three or more battery cell stacks may be arranged side by side in the third direction, wherein all normal directions of the first surfaces of each battery cell stack are parallel with the second direction.

[0041] The battery module may comprise 9 battery cell stacks arranged in the third direction.

[0042] Two battery cell stacks may be arranged back-to-back in the second direction, wherein the normal directions of the first surfaces of a first battery cell stack may be parallel with the second direction and the normal directions of the first surfaces of a second battery cell stack may be in a negative second direction.

[0043] The positive cell terminals and negative cell terminals for each battery cell may be electrically connected to the positive cell terminals and / or negative cell terminals of another battery cell.

[0044] The cell terminals of each battery cell are connected with metallic connection bars joined by laser welding.

[0045] The outer containment may be a polymeric layer, wherein the outer containment may be moulded around the outside of the battery module.

[0046] A polymer layer is moulded around the battery module to provide an insulation barrier.

[0047] The mechanical design of the battery module optimised to reduce or avoid air pockets in the outer containment.

[0048] The mechanical design of the battery module utilises the inherent structural strength of the battery cells to create a structurally reinforced battery module.

[0049] The battery module is tilted during moulding to allow air to escape and minimise the chances of entrapped air pockets or bubbles.

[0050] The outer containment may be provided with an at least one reduced thickness area aligned with the ventilation ports of the battery cells.

[0051] The outer containment may comprise removable inserts during the moulding process arranged in front of the ventilation ports resulting in reduced thickness areas. The ventilation port may rupture in case of high internal pressure, rupturing a metal ventilation port disk of the ventilation port.

[0052] A ruptured metal ventilation port disk may rupture the reduced thickness area adjacent to the ventilation port.

[0053] The outer containment may be provided with liquid-proof penetrations for power cables and signal cables.

[0054] The strapping device may be provided with a bottom support plate and a top support plate, wherein the bottom support plate and the top support plate may be arranged at a first end and a second end of the battery cell stack.

[0055] The bottom support plate and the top support plate extend over the whole surface of the first end and the second end of the battery cell stacks of the battery module.

[0056] The bottom support plate and the top support plate may be attachable to a support section, floor or base.

[0057] The bottom support plate and the top support plate may also be used for lifting the battery module.

[0058] The contact surfaces may be provided with insulation sheets.

[0059] The surface between a battery cell and the bottom support plate or the top support plate may also be provided with an insulation sheet.

[0060] The insulation sheets may be polycarbonate or similar materials.

[0061] The insulation sheets may provide electrical insulation and friction between the cells.

[0062] The contact surfaces may be provided with adhesive to create adhesion between the battery cells.

[0063] The adhesive may be in the form of paste adhesive or adhesive film that is applied prior to assembling the battery cells.

[0064] It is further defined a battery pack comprising:

[0065] - a containment structure;

[0066] - a plurality of battery modules as described above, wherein the battery modules are arranged spaced apart, wherein the first direction of the battery modules is vertical.

[0067] The battery pack may be a battery pack for maritime structures, such as a ship, barge, or any other floating structures. The batery pack may be a batery room.

[0068] The batery pack may be a batery room with similar structural integrity as a marine structure.

[0069] The first direction of the battery pack may be parallel with the gravitational force.

[0070] The battery modules may be arranged inside the containment structure with a longitudinal module-spacing-distance and / or a transverse module-spacing-distance between battery modules.

[0071] The battery modules may be mounted to, and / or are supported by a floor or a lower section of the containment structure.

[0072] The longitudinal module-spacing-distance and the transverse module-spacing- distance may be the same.

[0073] The battery pack may comprise:

[0074] - a gas exchange port, wherein the gas exchange port may be configured to control flow of gas out of the battery pack;

[0075] - a spray line and / or a drop line, wherein the spray line may be configured to provide cooling medium to the inside of the battery pack; wherein the drop line may be configured to provide cooling medium to the inside of the battery pack;

[0076] - a drain port, wherein the drain port may be configured to control the flow of cooling medium out of the battery pack.

[0077] The spray line inside the batery pack may be provided on the highest surface of the containment structure.

[0078] The battery pack may comprise:

[0079] - a gas exchange port, wherein the gas exchange port may be configured to control flow of gas out of the battery pack;

[0080] - a drop line, wherein the drop line may be configured to provide cooling medium to the inside of the battery pack;

[0081] - a drain port, wherein the drain port may be configured to control the flow of cooling medium out of the battery pack.

[0082] The inside of the battery pack may be filled with cooling medium at all times. The containment structure may be liquid- and gas tight, and / or provides mechanical strength for support of battery modules.

[0083] The containment structure may also provide thermal insulation to avoid excessive heat getting out of the battery pack or protect the battery pack against external fires.

[0084] It is further described a method for controlling temperature inside a battery pack, wherein the battery pack may comprise a temperature sensor, wherein the method may comprise the following steps:

[0085] - measuring temperature inside the battery pack using the temperature sensor;

[0086] - providing a cooling medium inside the battery pack using the spray line or drop line, wherein the level of cooling medium is controlled by a level transmitter;

[0087] - opening the drain port to drain the cooling medium from the inside of battery pack.

[0088] The cooling medium may be conditioned to stay within 0-45°C.

[0089] The cooling medium is preferably a liquid.

[0090] The cooling medium may be a non-flammable liquid.

[0091] The cooling medium may be a non-electrically conductive and high heat capacity liquid.

[0092] The cooling medium may be provided in the form of mist.

[0093] The cooling medium may be provided in the form of droplets.

[0094] The cooling medium may be water.

[0095] The cooling medium may be provided on the outside of the battery modules of the battery pack.

[0096] The battery pack may comprise a gas sensor, wherein the method may comprise the following steps:

[0097] - detecting gas inside the battery pack using a gas sensor;

[0098] - ventilating the gas from inside the battery pack to a safe location outside the battery pack;

[0099] - keeping the drain port closed to fill the inside of the battery pack with drop line.

[0100] In a thermal runaway event, the ventilation port of the battery cell may rupture due to high internal pressure, rupturing a metal ventilation port disk and rupturing the reduced thickness area and providing ventilation of hot gasses.

[0101] The open ventilation port of the battery cell may allow cooling medium to access the inside of the battery cell and cool the battery cell. It is further described a system for providing electric energy to a vessel, wherein the system comprises:

[0102] - a battery pack as described above;

[0103] - a skid with a cooling medium circulation system and a heat exchanger;

[0104] - a cooling medium storage; wherein the battery pack, the skid with the cooling medium circulation system and heat exchanger and the cooling medium storage are in fluid communication to each other.

[0105] The battery pack and method for controlling temperature inside a battery pack may have one or more of the following advantages:

[0106] • Providing a high energy density battery pack for maritime applications, with battery modules with integrated outer containment that do not require extra containment cases,

[0107] • Battery packs allowing ventilation and cooling of defective battery cells individually, thus minimising risk for overheating and spreading of the thermal runaway to neighbouring cells,

[0108] • Controlling the temperature of the battery pack by supplying cooling medium to the inside of the battery pack in line with maritime safety requirements,

[0109] • High efficiency cooling of battery cells, battery modules and battery packs by liquid cooling with a cooling medium.

[0110] • Overcoming of a technical prejudice by arranging battery cells horizontally allowing cells to be ventilated sideways and not upwards.

[0111] DESCRIPTION OF THE DRAWINGS

[0112] Following drawings are appended to facilitate the understanding of the claimed invention:

[0113] Fig. 1 - illustrates a perspective view of a single battery cell;

[0114] Fig. 2 - illustrates a perspective view of a battery stack;

[0115] Fig. 3 - illustrates a perspective view of a battery module side-by side arrangement of the battery stacks and a cut-off view of the out containment of the battery module;

[0116] Fig. 4 - illustrates a perspective view of a battery module with a back-to-back arrangement of the battery stacks; Fig. 5 - illustrates a perspective view of the battery module showing the electrical connection of the cells and bottom and top support plates;

[0117] Fig. 6 - illustrates a perspective view of the bottom and top support plates for battery stacks arranged back-to-back;

[0118] Fig. 7 - illustrates a perspective view of a battery module with outer containment;

[0119] Fig. 8 - illustrates a plan view of the ventilation port and the metal ventilation port disk for a battery cell;

[0120] Fig. 9 - illustrates a perspective view of the inside of the battery pack;

[0121] Fig. 10 - illustrates a perspective view of the outside of the battery pack;

[0122] Fig. 11 - illustrates a perspective view of an energy supply system for a vessel;

[0123] Fig. 12 - illustrates a perspective view of a single battery cell without ventilation port;

[0124] Fig. 13 - illustrates a perspective view of a battery stack without ventilation ports.

[0125] DETAILED DESCRIPTION

[0126] In the following, one or more specific embodiments of the invention will be described in more detail with reference to the drawings. However, it is specifically intended that the invention is not limited to the embodiments and illustrations contained herein but includes modified forms of the embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation- specific decisions must be made to achieve the developer’s specific goals, such as compliance with system and / or business -related constraints, which may vary from one implementation of the invention to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication and manufacture for the skilled person having the benefit of this disclosure.

[0127] The battery module 10

[0128] Figure 1 shows the battery cells 20 used in the assembly of the battery module 10. Each of the battery cells 20 comprises a first surface 21 which comprises a positive cell terminal 22A, a negative cell terminal 22B and a ventilation port 24.

[0129] Shown in figure 2, the battery cells 20 are arranged in a battery cell stack 31 extending in a first direction DI. The first direction DI is defined as the direction being perpendicular to a contact surface CS between two adjacent battery cells 20. All the battery cells 20 of the battery cell stack 31 are oriented in a second direction D2, i.e. all normal directions of the first surfaces 21 of each battery cell stack 31 are parallel with the second direction D2. The second direction D2 is perpendicular to the first direction DI and is also perpendicular to the first surfaces 21 of the battery cells 20.

[0130] Also shown in figure 2, the battery cell stack 31 has a third direction D3. The third direction is perpendicular to the first direction DI and the second direction D2.

[0131] In figure 3 it is shown that the battery module 10 also comprises a strapping device 40 extending at least in the first direction DI such as to compress the battery cells 20 towards each other. This reduces swelling of the battery cells and keeps the battery stack together.

[0132] Also shown in figure 3 is the outer containment 50 which encloses the battery module 1. The battery cells 20 may be arranged in a positive or negative first direction DI. Furthermore, the battery cells 20 of the battery cell stack 31 may be oriented in a positive or negative second direction (D2). Typical battery cell stack 31 configurations are 15 or 16 cells arranged in a first direction DI.

[0133] The battery cells 20 are typically prismatic cells. As the cells are in a horizontal position during use, and the ventilation port 24 is pointing sideways, into the second direction D2. To ensure that electrolyte is not lost between anode and cathode windings inside the cell 20, the cells 20 are filled with electrolyte two times during production to eliminate risk for loss of electrolyte.

[0134] Figures 3 and 4 illustrate how the battery cell stacks 31 are assembled to form a battery module 10. As shown in figure 3, two battery cell stacks 31 may be arranged side by side in the third direction D3, wherein all normal directions of the first surfaces 21 of each battery cell stack 31 are parallel with the second direction D2. Battery cell stacks 31 may be arranged side by side in the positive or negative third direction D3.

[0135] It is possible to arrange 3 or more battery cell stack 31 as outlined above. For example, three or more battery cell stacks 31 may be arranged side by side in the third direction D3, wherein all normal directions of the first surfaces 21 of each battery cell stack 31 are parallel with the second direction D2. In one embodiment, the battery module 10 may comprise 9 battery cell stacks 31 arranged in the third direction D3.

[0136] As shown in figure 4, two battery cell stacks 31 are arranged back-to-back in the second direction D2, wherein the normal directions of the first surfaces 21 of a first battery cell stack 31 are parallel with the second direction D2 and the normal directions of the first surfaces 21 of a second battery cell stack 31 are in a negative second direction D2.

[0137] Illustrated in figure 5, the positive cell terminals 22A and negative cell terminals 22B for each battery cell 20 are electrically connected to the positive cell terminals 22A and / or negative cell terminals 22B of another battery cell 20. The cell terminals 22A, 22B of each battery cell 20 are connected by metallic connection bars 26 joined by laser welding. Some typical parameters for such a laser weld are a melt depth of l-3mm, a melt width of l-3mm with a peak temperature at the cell terminals 22A, 22B of 250° C for 10 seconds.

[0138] Also shown in figure 5, is that the strapping device 40 is provided with a bottom support plate 45 and a top support plate 46. The bottom support plate 45 is arranged at the first end 31f of the battery cell stack(s) 31 while the top support plate 46 is arranged at the second end 31s of the battery cell stack(s) 31. The bottom support plate 45 and top support plate 46 for battery stacks 31 arranged back-to -back are shown in figure 6.

[0139] The bottom support plate 45 extends over the whole surface of the first end 3 If of the battery cell stacks 31 while the top support plate 46 extends over the whole surface of the second end 31s of the battery cell stacks 31.

[0140] The bottom support plate 45 and the top support plate 46 may be attachable to a support section, floor or base to fasten the battery cell stack 31. The bottom support plate 45 and the top support plate 46 may also be used for lifting the battery module 10.

[0141] The contact surfaces CS between two adjacent battery cells 20 are provided with insulation sheets 38. The insulation sheets 38 provide electrical insulation and friction between the cells 20 and are typically made of polycarbonate, foam or similar materials. The surface between a battery cell 20 and the bottom support plate 45 or the top support plate 46 may also be provided with an insulation sheet 38.

[0142] In addition, the contact surfaces CS may be provided with adhesive to create adhesion between the battery cells 20. Examples of adhesives are a thermoplastic, epoxy, modified epoxy, phenolic, polyurethane adhesives. The adhesive may be in the form of paste adhesive or adhesive film that is applied prior to assembling the battery cells 20 by e.g. spatula or automatic dispenser, or pre glued insulation sheets.

[0143] The insulation sheets 38 and or adhesive layer have a thickness in the range of 0.1 to 1 mm. A batery management system (BMS, not shown) for the battery module 10 and an independent overcharge protection module (OPM, not shown) may be encapsulated in an IP68 cage, and / or a Faraday cage (not shown) that is arranged in the vicinity of or fixed onto the top of the battery module 10.

[0144] If the BMS is provided in the vicinity to the battery module 10, then Faraday cage also provides a fluid, gas and pressure proof and dust proof containment for the BMS.

[0145] Optionally, if the battery cell includes a current interruption device (CID), the OPM can be skipped. The CID may be useful for preventing overcharge and guard against fire or explosion in the event where the battery cell 20 is exposed to overcurrent or over temperature. If CID is included in the battery cell 20, an independent system for overcharge protection will typically not be required.

[0146] The module BMS and the OPM system are each connected to the battery module 10 with marine approved shielded signal and / or power cables.

[0147] The battery module 10 - alternative battery cells 20

[0148] In the following section, a further embodiment of the battery module 10 is presented. Only differences between this embodiment and the battery module 10 are discussed.

[0149] In this embodiment, alternative battery cells 20 are used as shown in figures 12 and 13. The alternative battery cells 20 are protected against fire and explosion during a thermal runaway and require therefore no ventilation port. The alternative battery cells 20 should comply with the new Chinese battery safety standard GB38031- 2025. The alternative battery cells 20 must not catch fire or explode for 120 minutes after a thermal event. Internal temperatures must stay under 60 °C.

[0150] The outer containment 50 of the battery module 10

[0151] Figures 3 and 7 show the outer containment 50 of the battery module 10. The outer containment 50 may be a polymeric layer, which is moulded around the outside of the battery module 10. The polymer layer provides an insulation barrier, both electrical insulation, fire insulation as well as protection against the outside environment such as humidity, air or gasses and dust and contamination. The thickness of the outer containment 50 may be in the range of 1 to 30mm.

[0152] The preferred method for producing the outer containment 50 is a casting or moulding process. The mechanical design of the battery module 10 is optimised to reduce or avoid air pockets or voids in the outer containment 50 during production. To further reduce air entrapment, the battery module 10 is tilted during moulding to allow air to escape. The polymer layer of the outer containment 50 may be reinforced by fibres and / or fabrics.

[0153] The material used for the casting or moulding process may be a ductile, non- conductive and liquid and gas tight polymers, such as Polyurethane, Polyethylene Terephthalate (PET or PETE), High-Density Polyethylene (HDPE), Polyvinyl Chloride (PVC or Vinyl), Low-Density Polyethylene (LDPE), Polypropylene (PP), Polystyrene (PS or Styrofoam). The polymer material has sufficient ductility to allow the battery cells 20 to expand and contract without rupture.

[0154] The polymer material, used for encapsulation, is liquid-tight, flame retardant and may have a thermal conductivity of > 0.51 W / mk. The polymer material is designed for immersion in water, water glycol, transformer oil, Novec fluid, and / or seawater for more than 25 years without significant degradation of its physical properties such as liquid and gas tightness. Furthermore, the polymer material can have > 1 MPa tensile, lap shear strength to metals including aluminium and steel. Thus, high thermal conductivity, adhesion and sealing properties are being combined with extreme dielectric strength.

[0155] Also shown in figure 7, are liquid-proof penetrations for the power cables 61 and signal cables 65. Here, the cables 61, 65 are pretreated chemically and mechanically. The liquid and gas tight penetrations are verified with a vacuum test and satisfy both IP 68 and IP69K classification requirements.

[0156] The outer containment 50 may also be provided with a reduced thickness areas 50a that are aligned with the ventilation ports 24 of the battery cells 20. The reduced thickness area 50a has typically a thickness in the range of 0.5 - 10 mm. One option to produce the reduced thickness areas 50a is to insert removable inserts during the moulding process.

[0157] In case of high temperature or fire in a cell 20, gas my develop leading to high internal pressure in the cell 20. The metal ventilation port disk 24d, shown in figure 8, is ruptured, cutting and rapturing the reduced thickness area 50a adjacent to the ventilation port 24 and enabling the gasses to escape. The advantage of introducing a reduced thickness area 50a is to control where the outer containments 50 is ruptured when a cell 20 fails thus minimising damage to neighbouring cells 20 and eliminating risk for conductive liquid to enter a space or cavity between the battery module 10 and the outer containment 50 potentially causing short circuits, electrolysis production and gas ignition.

[0158] When producing the outer containment 50, the Faraday cage containing the BMS, and optionally or additionally the OPM, are also encapsulated by the outer containment 50. In the embodiment where the BMS is separate or outside the battery module 10, the outer containment 50 provides liquid-proof penetrations for the power and signal cables of the BMS. In both embodiments, the BMS is protected from a subsea / wet environment.

[0159] The battery pack 100

[0160] A battery pack 100 comprises a containment structure 110 and several battery modules 10 as shown in figure 9. The containment structure 110 is liquid and gas tight and / or mechanical strength for support of the battery modules 10 when exposed to static and dynamic loads. The containment structure 110 also provides thermal insulation, such as A60 insulation, to avoid excessive heat getting out of the battery pack 100 or protect the battery pack 100 against external fires.

[0161] The battery modules 10 are arranged spaced apart inside the containment structure 110 to allow the circulation of air, gas and liquid between the battery modules 10. The battery pack 100 may be a battery pack for a vessel 1050, such as a maritime structure, ship, barge, or any other floating structures. The battery containment structure 110 may also be classified as a battery room on board of a vessel 1050 in accordance with rules and regulations, such as SOLAS or classification society rules.

[0162] Also shown in figure 9, is that the first direction DI of the battery modules 10 is vertical and usually parallel with the gravitational force when the vessel 1050 is stationary and for example in a harbour. When the vessel 1050 is in transit, it may experience (wave) motion such as rolling and pitching resulting in temporary misalignment of direction DI and the direction of the gravitational force.

[0163] The battery modules 10, as shown in figure 9, may be arranged inside the containment structure 110 with a longitudinal module-spacing-distance LI and / or a transverse module-spacing-distance T2 between battery modules 10 to allow gas or liquid to pass between the battery modules 10. In some instances, the longitudinal module-spacing-distance LI and the transverse module-spacing-distance T2 may be the same.

[0164] The battery pack 100 may alternatively use battery modules 10 with alternative battery cells 20 as shown in figures 12 and 13. The battery modules 10 with alternative battery cells 20 would be arranged or spaced in the same way as the battery modules 10.

[0165] The battery pack 100 also comprises, as shown in figure 10, a gas exchange port 130 that controls flow of gas out of the battery pack 100, a spray line 140 and a drop line 141 to provide cooling medium to the inside of the battery pack 100. The spray line 140 inside the battery pack 100 may be provided on the highest surface of the containment structure 110. Furthermore, the battery pack 100 comprises a drain port 148 as shown in figure 9. The drain port 148 is configured to control the flow of cooling medium out of the battery pack 100. Drain ports can be placed in other locations in the containment structure 110 than the one shown in figure 9.

[0166] The battery pack 100 - alternative embodiment

[0167] In the following section, a further embodiment of the battery pack 100 is presented. Only differences between this embodiment and the battery pack 100 are discussed.

[0168] The alternative embodiment of the battery pack 100 is a battery pack 100 where the inside of the battery pack 100 is always filled with cooling medium.

[0169] The purpose is to simplify the construction and operation of the battery pack 100 by not having a spray line 140 and the associated nozzles, and to create an inherently (fire) safe sy sieur

[0170] A method for controlling temperature inside a battery pack 100

[0171] There are two main scenarios for controlling the temperature inside the battery pack 100. (i) conditioning of the temperature of the battery modules 10 and (ii) cooling a cell 20 where a thermal runaway event is about to occur. In both cases, cooling medium is provided in the spaces between the battery modules 10. These spaces in the longitudinal and transverse direction are denoted by the longitudinal modulespacing-distance LI and the transverse module-spacing-distance T2.

[0172] The temperature inside the battery pack is monitored by temperature sensor 105 as shown in figure 10. The method comprises measuring temperature inside the battery pack 100 using the temperature sensor 105 and providing cooling medium inside the battery pack 100 using the spray line 140 and / or the drop line 141. Excess cooling medium is drained by the drain port 148. Cooling medium level is monitored with a level transmitter 106. In a fire event, if required by rules and regulations, fire suppression medium can be supplied to the battery pack 100 through the spray line 140 from a dedicated fire suppression system (not shown in the figures).

[0173] The cooling medium is a liquid such as fresh water, fresh water with 10-50% glycol, transformer oil, Novec fluid, and / or seawater. The cooling medium is conditioned to be within 0-45°C. Furthermore, the cooling medium may be provided in the form of mist or droplets on the outside of the battery modules 10 of the battery pack 100. The cooling medium is provided from the highest point in the battery pack 100 and drips or percolates downwards on the surface of the battery modules 10. Hence, cooling (or heating) is achieved by heat conduction between the battery cells 20 and the outer containment 50 and the liquid cooling provided by the cooling medium on the surface of the outer containment 50. The batery pack 100 is furthermore equipped with a gas sensor 107, see also figure 10. In a thermal runaway event, gas develops inside a cell 20, the metal ventilation port disk 24d burst and ruptures the outer containment 50, hereby releasing gas to the inside of the battery pack 100. The gas senor 107 detects the gas and ventilates the gas from the inside of the battery pack 100 to a safe location outside the battery pack 100. This avoids the flammable and hazardous gas getting in contact with adjacent cells preventing contact with ignition sources and or spread of heat / convection heat transfer to adjacent cells from hot gas.

[0174] The drop line 141 fills the inside of the battery pack 100 with cooling medium. This time the drain port 148 is kept closed to rapidly flood the inside of the battery pack 100. The inside of the damaged cell 20 is flooded through the raptured ventilation port 24 with cooling medium to prevent overheating and spreading of the thermal runaway to neighbouring cells 20.

[0175] For the alternative embodiment of the battery pack 100, the inside of the battery pack 100 is always filled with cooling medium. This simplifies the method for controlling temperature inside the battery pack 100 as the step of providing cooling medium in the spaces between the batery modules 10 is avoided.

[0176] An energy supply system 1000 for a vessel 1050

[0177] Figure 11 shows a system 1000 for providing electric energy to a vessel 1050, such as a ship or maritime structure. The system 1000 comprises a battery pack 100 as described above, a skid 1010 with a cooling medium circulation system and a heat exchanger and a cooling medium storage 1030 which are all in fluid communication to each other.

[0178] Heat exchange can be directly with sea water in a standard plate heat exchanger minimizing energy consumption for temperature control, i.e. the energy consumption for cooling demand may constitute only 1-5% of the energy carrying capacity of the battery pack 100. This is a considerable saving when compared with the energy consumption for cooling demands for prior art systems, which may in some cases constitute as much as 10-30% of the assembly’s energy carrying capacity depending on operation profile and C-rate requirement.

[0179] In the preceding description, various aspects of the apparatus and method according to the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the apparatus and its workings. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments of the apparatus and method, which are apparent to person skilled in the art to which the disclosed subject-matter pertains, are deemed to lie within the scope of the present invention as defined by the following claims.

[0180] LIST OF REFERENCE NUMBERS

[0181] 10 - batery module

[0182] 20 - batery cell

[0183] 21 - first surface of the batery cell 20

[0184] 22A - positive cell terminal

[0185] 22B - negative cell terminal

[0186] 24 - ventilation port

[0187] 24d - metal ventilation port disk

[0188] 26 - metallic connection bars

[0189] 31 - batery cell stack

[0190] 3 If - first end

[0191] 31s - second end

[0192] 38 - insulation sheet

[0193] 40 - strapping device

[0194] 45 - botom support plate

[0195] 46 - top support plate

[0196] 50 - outer containment

[0197] 50a - reduced thickness area

[0198] 52 - fibres and / or fabrics for reinforcing the outer containment

[0199] 61 - power cables

[0200] 65 - signal cables

[0201] 100 - batery pack

[0202] 105 - temperature sensor

[0203] 106 - level transmiter

[0204] 107 - gas sensor

[0205] 110 - containment structure

[0206] 130 - gas exchange port

[0207] 140 - spray line

[0208] 141 - drop line

[0209] 148 - drain port

[0210] 1000 - system for providing electric energy to a vessel

[0211] 1010 - skid with a cooling medium circulation system and a heat exchanger

[0212] 1030 - cooling medium storage

[0213] 1050 - vessel

[0214] BMS - batery management system

[0215] CS - contact surface

[0216] DI - first direction

[0217] D2 - second direction

[0218] D3 - third direction

[0219] LI - longitudinal module-spacing-distance

[0220] OPM - overcharge protection module

[0221] T2 - transverse module-spacing-distance

Claims

CLAIMS1. A batery module (10) comprising:- a plurality of batery cells (20), wherein each of the battery cells (20) comprises a first surface (21) which comprises a positive cell terminal (22A) and a negative cell terminal (22B), wherein the battery cells (20) are arranged in a battery cell stack (31) extending in a first direction (DI), wherein the first direction (DI) is perpendicular to a contact surface (CS) between two adjacent battery cells (20), wherein all the battery cells (20) of the battery cell stack (31) are oriented in a second direction (D2), wherein the second direction (D2) is perpendicular to the first direction (DI) and is also perpendicular to the first surfaces (21) of the battery cells (20), wherein the battery cell stack (31) has a third direction (D3), wherein the third direction is perpendicular to the first direction (DI) and the second direction (D2);- a strapping device (40), wherein the strapping device (40) extends at least in the first direction (DI) such as to compress the battery cells (20) towards each other;- an outer containment (50), wherein the outer containment (50) encloses the battery module (10).

2. The battery module (10) according to claim 1, wherein the first surface (21) comprises a ventilation port (24).

3. The battery module (10) according to any one of the previous claims, wherein two or more battery cell stacks (31) are arranged side by side in the third direction (D3), wherein all normal directions of the first surfaces (21) of each battery cell stack (31) are parallel with the second direction (D2).

4. The battery module (10) according to any one of the previous claims , wherein two battery cell stacks (31) are arranged back-to-back in the second direction (D2), wherein the normal directions of the first surfaces (21) of a first battery cell stack (31) are parallel with the second direction (D2) and the normal directions of the first surfaces (21) of a second battery cell stack (31) are in a negative second direction (D2).

5. The batery module (10) according to any one of the previous claims, wherein the positive cell terminals (22A) and negative cell terminals (22B) for each battery cell (20) are electrically connected to the positive cell terminals (22A) and / or negative cell terminals (22B) of another battery cell (20).

6. The battery module (10) according to any one of the previous claims, wherein the outer containment (50) is a polymeric layer, wherein the outer containment is moulded around the outside of the battery module (10).

7. The battery module (10) according to any one of the previous claims, wherein the outer containment (50) is provided with an at last one reduced thickness area (50a) aligned with the ventilation ports (24) of the battery cells (20).

8. The battery module (10) according to any one of the previous claims, wherein the outer containment (50) is provided with liquid-proof penetrations for power cables (61) and signal cables (65).

9. The battery module (10) according to anyone of the previous claims, wherein the strapping device (40) is provided with a bottom support plate (45) and a top support plate (46), wherein the bottom support plate (45) and the top support plate (46) are arranged at a first end (3 If) and a second end (31s) of the battery cell stack (31).

10. The battery module (10) according to anyone of the previous claims, wherein the contact surfaces (CS) are provided with insulation sheets (38).

11. A battery pack (100) comprising:- a containment structure (110);- a plurality of battery modules (10) according to anyone of claims 1 to 10, wherein the batery modules (10) are arranged spaced apart, wherein the first direction (DI) of the battery modules (10) is vertical.

12. The batery pack (100) according to claim 11, wherein the battery pack (100) comprises:- a gas exchange port (130), wherein the gas exchange port (130) is configured to control flow of gas out of the battery pack (100);- a spray line (140) and / or a drop line (141), wherein the spray line (140) is configured to provide cooling medium to the inside of the battery pack (100), wherein the drop line (141) is configured to provide cooling medium to the inside of the battery pack (100);;- a drain port (148), wherein the drain port (148) is configured to control the flow of cooling medium out of the battery pack (100).

13. The battery pack (100) according to claim 11, wherein the battery pack (100) comprises:- a gas exchange port (130), wherein the gas exchange port (130) is configured to control flow of gas out of the battery pack (100);- a drop line (141), wherein the drop line (141) is configured to provide cooling medium to the inside of the battery pack (100);;- a drain port (148), wherein the drain port (148) is configured to control the flow of cooling medium out of the battery pack (100).

14. The battery pack (100) according to anyone of claims 11 to 13, wherein the containment structure (110) is liquid- and gas tight, and / or provides mechanical strength for support of battery modules (10).

15. A method for controlling temperature inside a battery pack (100) according to claim 12, wherein the battery pack (100) comprises a temperature sensor (105), wherein the method comprises the following steps:- measuring temperature inside the battery pack (100) using the temperature sensor (105);- providing a cooling medium inside the battery pack (100) using the spray line (140) or drop line (141), wherein the level of cooling medium is controlled by a level transmitter (106);- opening the drain port (148) to drain the cooling medium from the inside of battery pack (100).

16. The method according to claim 15, wherein the battery pack (100) comprises a gas sensor (107), wherein the method comprises the following steps:- detecting gas inside the battery pack (100) using a gas sensor (107);- ventilating the gas from inside the battery pack (100) to a safe location outside the battery pack (100);- keeping the drain port (148) closed to fill the inside of the battery pack (100) with the drop line (141).

17. A system (1000) for providing electric energy to a vessel (1050), wherein the system (1000) comprises:- a battery pack (100) according to claims 11 - 14;- a skid (1010) with a cooling medium circulation system and a heat exchanger;- a cooling medium storage (1030); wherein the battery pack (100), the skid (1010) with the cooling medium circulation system and heat exchanger and the cooling medium storage (1030) are in fluid communication to each other.

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