Battery module and battery pack

Abstract

Battery module (3) comprising a battery unit (4), an electronic unit (5) and a cooling unit (6), wherein the battery unit (4) is arranged between the electronic unit (5) and the cooling unit (6), characterized in that a thermal insulation layer (13, 14) contacts the cooling unit (6) on a side (12) opposite the battery unit (4) and / or contacts the electronic unit (5) on a side (15) opposite the battery unit (4).

Description

State of the art

[0001] The invention relates to a battery module comprising a battery unit, an electronic unit, and a cooling unit, wherein the battery unit is arranged between the electronic unit and the cooling unit. The invention further relates to an arrangement comprising at least two such battery modules and a battery pack in which at least one such battery module is accommodated. The invention also relates to a vehicle with such a battery pack.

[0002] Electrochemical processes in a battery are strongly influenced by its operation and storage temperature. Higher temperatures improve electron or ion mobility, thereby reducing the cell's internal impedance and increasing its capacity. However, high temperatures can also trigger undesirable or irreversible chemical reactions and / or electrolyte loss, potentially leading to permanent damage or total battery failure. Lithium-ion batteries react to overheating or overcharging with thermal runaway. Thermal runaway in a battery occurs in several stages, with each stage causing further damage to the cell. Particularly high currents, overcharging, or high ambient temperatures lead to overheating within the cell, which can cause the thin solid electrolyte layer on the anode to dissolve.The dissolution of this protective layer on the anode leads to a reaction between the electrolyte and the anode surface (e.g., carbon), which is inherently exothermic and therefore further increases the temperature of the battery cell. When exothermic reactions occur on the anode surface, the resulting heat decomposes the organic solvents present in the electrolyte, releasing flammable gases such as ethane, methane, and other hydrocarbon gases.

[0003] On the other hand, the electrolyte can freeze at low temperatures, which limits low-temperature performance. However, battery performance already deteriorates well above the electrolyte's freezing point, while the chemical reaction also decreases. This low-temperature operating limit of a battery can depend on its state of charge.

[0004] It is therefore necessary to keep the battery within a limited operating temperature range so that both its charging capacity and cycle life can be optimized. In a practical system, both heating and cooling of the battery are required to keep it not only within the operating limits specified by the manufacturer, but within a further restricted range to achieve optimal performance. Effective thermal management ensures the necessary temperature range for optimal battery cell performance.

[0005] US Patent 2006 / 0261304A1 discloses an insulated electronic device comprising a heat-generating component that is at least partially covered with at least one layer of a fiber-reinforced aerogel composition. Furthermore, methods for insulating electronic devices such as various fuel cells are described. Such thermal management can be applied to power sources such as lithium-ion batteries.

[0006] JP 2006-196 230 A discloses a battery pack consisting of a plurality of stacked battery cells, wherein an insulating element is inserted between the battery cells. The battery pack also has a cooling element inserted between the battery cells.

[0007] The state of the art in this regard is still represented by the publications EP 2 667 076 B1, EP 2 068 390 A1, US 2011 / 0 293 974 A1 and JP 2004- 63 352 A. Disclosure of the invention Advantages of the invention

[0008] According to the invention, in a battery module comprising at least one battery unit, at least one electronic unit and at least one cooling unit, the battery unit is arranged between the electronic unit and the cooling unit, and a thermal insulation layer contacts the cooling unit on a side opposite the battery unit and / or contacts the electronic unit on a side opposite the battery unit.

[0009] For example, the battery unit can be contacted on one side by the electronic unit, on a second side opposite the first by the cooling unit, and the cooling unit can be contacted on one side opposite the battery unit by the thermal insulation layer.

[0010] To prevent condensation, the exposed parts of the cooling unit—that is, the parts not in contact with the battery unit—are in contact with a thermal insulation layer, for example, coated with thermally insulating aerogel and / or X-aerogel coatings. Thanks to the insulation layer present on all exposed surfaces, condensation on the cooling unit's surfaces is prevented. The cooling unit, which is thermally insulated on at least one side, also enables efficient, directed dissipation of the heat generated by the battery units. This ensures that the battery cells can be maintained at an optimal temperature, especially during the winter months.

[0011] Alternatively or preferably additionally, the battery unit can be contacted on a first side by the electronic unit, on a second side opposite the first side by the cooling unit, and the electronic unit can be contacted on a side opposite the battery unit by the thermal insulation layer.

[0012] The electronic unit, which is at least thermally insulated on one side, exhibits reduced susceptibility to moisture condensation. Due to the absence of airtight battery pack housings, condensation of the gases contained within the battery pack is inevitable. Without thermal insulation, both the surfaces of the electronic components and the surfaces of the battery terminals, which form part of the wiring harness, are susceptible to moisture condensation.

[0013] In this description, the terms "battery" and "battery unit" are used in accordance with common usage to refer to accumulators and accumulator units, respectively. Battery units can refer to one or more battery cells that are grouped together and connected via a circuit, for example, in series or parallel.

[0014] In a preferred embodiment, the thermal insulation layer comprises an aerogel or an X-aerogel, i.e., a cross-linked aerogel. Aerogels or X-aerogels are highly porous solids in which a large percentage of the volume consists of pores, for example, more than 99%, more than 99.9%, or more than 99.98%. Aerogels can be produced by aerogel synthesis, for example, by means of a sol-gel process, whereby a silicate-based aerogel can be used. An aerogel or X-aerogel with a thermal conductivity in the range of 10 to 20 mW / m is particularly advantageous. -1 K -1The following materials are used: chemically inert aerogels or X-aerogels, which do not react with the materials present in the battery cell, are preferred. Non-flammable and non-toxic aerogels or X-aerogels are also preferred. Particularly preferred are film-like aerogel layers, for example from the manufacturer Aspen Aerogel, or coatings, for example from the manufacturer Cabot Aerogel. The film thickness and layer thickness are preferably in the range of 5 µm to 5 mm.

[0015] Suitable cooling units include, for example, a coolant circulating in a cooling block, as well as fans, ventilators, or heat pipes. A heat pipe, for instance, is a simple tube closed at both ends, with a capillary material present between the ends. The pressure inside the heat pipe is so low that a liquid, such as water, exists in an equilibrium state between the liquid and gaseous states, consequently evaporating in a warmer section and condensing in a cooler section. This provides very efficient heat transfer. One end of the heat pipe is in contact with the battery pack, and the other end is in contact with a heat sink, such as a cooling block, which can also be located outside the battery pack.

[0016] The electronic unit, which is thermally insulated on at least one side, is preferably configured for controlling and monitoring the battery unit. It can, for example, include a control unit in the form of a battery management system that monitors the safe and reliable operation of the battery cells. The electronic unit can include devices for monitoring and controlling currents, voltages, temperatures, insulation resistances, and other parameters for individual battery cells. These parameters enable the implementation of battery management functions that increase the service life, reliability, and safety of the battery pack. In particular, the electronic unit can include switching electronics for selectively connecting and disconnecting the battery module to a battery direct converter or a battery direct inverter.

[0017] Following a step in the manufacturing process, an assembly can be created comprising at least two battery modules held within a frame. The frame advantageously enables the fixed spatial arrangement of the battery modules relative to each other.

[0018] The battery module is preferably designed in a substantially cuboid shape. Preferably, the battery module comprises at least one substantially cuboid battery unit, one substantially cuboid electronic unit, and one substantially cuboid cooling unit. This is suitable for a compact, modular design of a battery pack, which offers advantages in battery pack maintenance and also promises free scalability of the system. Advantageously, the battery modules are thermally insulated from each other at the relevant points.

[0019] According to the invention, an arrangement is proposed comprising at least two such battery modules, wherein the battery modules are preferably arranged one above the other, such that the thermal insulation layer of a first battery module thermally insulates the electronic unit of a second battery module from the cooling unit of the first battery module. The intended insulating effect can, of course, also be achieved if, due to the chosen battery module shape, several thermal insulation layers are arranged one above the other, either directly or separated by a layer of the frame. Several of these cuboid battery modules can form so-called battery direct converters (BDCs), and several battery direct converters can form a battery direct inverter (BDI).

[0020] According to a further aspect of the invention, a battery pack comprises a housing in which at least one described battery module or at least an arrangement with at least two battery modules is accommodated. According to one embodiment, the thermal insulation layer of a bottommost battery module insulates it from the bottom of the housing.

[0021] According to further embodiments, it may be provided that a further thermal insulation layer is provided, which is arranged below the frame and on the housing base and thermally insulates the heat sinks from the housing base.

[0022] In the case of a battery pack where the cooling unit is located at the bottom of the housing, cooling of the battery pack housing can be avoided by applying thermally insulating materials made of aerogel and / or X-aerogel to the bottom of the battery pack housing. Cooling the battery pack housing should be avoided because simultaneously cooling the battery pack housing and the battery modules of the battery pack requires greater efficiency from the overall cooling system of the electric vehicle. Increased cooling efficiency of the battery pack through a cooling unit ultimately also requires increased efficiency from the vehicle's cooling system, for example, the air conditioning unit. If the battery pack housing is cooled in addition to the battery modules, higher cooling demands are placed on the vehicle's cooling system, for example, the air conditioning unit, which in turn requires more energy.Therefore, providing better insulation to cool only the battery pack and not the housing is a crucial step towards an energy-saving and cost-effective overall thermal management concept for electric vehicles. Limiting the cooling to the bottom area, excluding the sides and roof of the battery housing, can offer cost advantages and simplifies manufacturing.

[0023] Another aspect proposes a vehicle with such a battery pack, where the battery pack is connected to the vehicle's drive system. This battery pack is used in electrically powered vehicles, where a large number of battery cells are interconnected to provide the necessary drive voltage. Brief description of the drawings

[0024] Exemplary embodiments of the invention are shown in the drawings and explained in more detail in the following description. They show: Fig. 1 a schematic representation of a state-of-the-art battery pack and Fig. 2 a schematic representation of a battery pack according to the invention and Fig. 3 a further schematic representation of a battery pack according to the invention.

[0025] Fig. Figure 1 shows a state-of-the-art battery pack 1. Within the battery pack 1, two battery modules 3 are arranged one above the other in a housing 2. Each battery module 3 comprises a battery unit 4, in which several battery cells are typically connected in series and additionally in parallel to achieve the required performance and energy data for the battery pack 1. The battery modules 3 are mounted in a frame 7, which is arranged on a housing base 8.

[0026] In the illustrated embodiment, the battery modules 3 are arranged relative to each other such that a cooling unit 6 is in thermal contact with the battery unit 4 located above it and with components located below it. In the case of the upper battery module 3, the cooling unit 6 is in thermal contact with the electronic unit 5 of the lower battery module 3. In the case of the lower battery module 3, the cooling unit 6 is in thermal contact with the housing base 8.

[0027] Between the battery unit 4 of the lower battery module 3 and the cooling unit 6 of the upper battery module 3, there are generally electronic components and a cable harness of the electronic unit 5. Without thermal insulation, both the surfaces of the electronic components and the surfaces of the battery terminals, which form part of the cable harness of the electronic unit 5, are susceptible to moisture condensation.

[0028] Fig. Figure 2 shows a schematic representation of a battery pack 1 according to a first embodiment of the invention. In the illustrated embodiment, the battery pack 1 comprises, by way of example, two battery modules 3 housed in a common casing 2 and arranged one above the other. Each battery module 3 comprises a battery unit 4 in which several battery cells are typically connected in series and additionally in parallel to achieve the required performance and energy data with the battery pack 1. The individual battery cells are, for example, lithium-ion batteries with a voltage range of 2.8 to 4.2 volts.

[0029] The battery units 4 are arranged between the electronic unit 5 and the cooling unit 6 and are contacted on a first side 9 by the electronic unit 5 and on a second side 10, which is opposite the first side 9, by the cooling unit 6 on its first side 11. Fig. Figure 2 also shows a frame 7 which holds the battery modules 3. The frame 7 is arranged on the housing base 8. Another layer of the frame 7 is shown between the battery modules 3.

[0030] The cooling unit 6 is contacted on a second side 12, which is opposite the first side 11, by a thermal insulation layer 13. The thermal insulation layer 13 is a film or forms a coating of the cooling unit 6 and is made of an aerogel or an X-aerogel.

[0031] Both battery modules 3 have an additional thermal insulation layer 14 to insulate the electronic unit 5 of the battery module 3 from the environment. This additional thermal insulation layer 14 is a film or forms a coating of the electronic unit 5 and is made of an aerogel or an X-aerogel. It is arranged on a first side 15 of the electronic unit 5, which faces a second side 16 that contacts the battery unit 4.

[0032] The thermal insulation layer 13 of the lower battery module 3 insulates the cooling unit 6 of the lower battery module 3 from the housing base 8. In this embodiment, a further thermal insulation layer 17 is provided, which is arranged below the frame 7 and also insulates the cooling unit 6 of the lower battery module 3 from the housing base 8.

[0033] Fig. Figure 3 shows a schematic representation of a battery pack 1 according to a further embodiment of the invention. In the illustrated embodiment, the battery pack 1 again comprises, by way of example, two battery modules 3 housed in a common casing 2 and arranged one above the other. The illustration shows only the functional layer sequence of the two battery modules 3, not their relative sizes. The battery unit 4 is arranged between the electronic unit 5 and the cooling unit 6 and is contacted by the electronic unit 5 at its first side 15. The electronic unit 5 is contacted by the thermal insulation layer 14 at the side 16 opposite the battery unit 4. The thermal insulation layer 14 is a film or forms a coating of the electronic unit 5 and is made of an aerogel or an X-aerogel.

[0034] In this embodiment, the additional thermal insulation layer 17 is again provided to insulate the cooling unit 6 of the lowest battery module 3 of a stack from the housing base 8. The additional thermal insulation layer 17 can be a film or form a coating of the cooling unit 6 and is made of an aerogel or an X-aerogel. Alternatively, it can also be arranged as a plate or film below a framework 7 (not shown), as described in relation to Fig. 1 described.

[0035] The in the Fig. 2 and Fig.The battery modules 3 shown in Figure 3 preferably have a cuboid structure, which allows for easy stacking to form a battery module string of a battery direct converter or a battery direct inverter. Although only two stacked battery modules 3 are shown, the invention is not limited to this specific embodiment. On the contrary, the presented insulation structure introduces a modular concept that is applicable to battery packs 1 with any number of battery modules 3 arranged one above the other and side by side.

[0036] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, within the scope specified by the claims, a multitude of modifications are possible that fall within the bounds of what is considered skilled in the art.

Claims

[1] Battery module (3) comprising a battery unit (4), an electronic unit (5) and a cooling unit (6), wherein the battery unit (4) is arranged between the electronic unit (5) and the cooling unit (6), characterized by , that a thermal insulation layer (13, 14) contacts the cooling unit (6) on one side (12) opposite the battery unit (4) and / or contacts the electronic unit (5) on one side (15) opposite the battery unit (4). [2] Battery module (3) according to claim 1, characterized by that the thermal insulation layer (13, 14) comprises an aerogel or an X-aerogel. [3] Battery module (3) according to any one of the preceding claims, characterized by , that the cooling unit (6) has a coolant circulating in a cooling block or at least a fan, ventilator or heat pipes. [4] Battery module (3) according to any one of the preceding claims, characterized by, that the electronic unit (5) is set up to control and monitor the battery unit (4). [5] Arrangement with at least two battery modules (3) according to one of claims 1 to 4, wherein the battery modules (3) are arranged one above the other, so that the thermal insulation layer (13, 14) of a first battery module (3) thermally insulates the electronic unit (5) of a second battery module (3) from the cooling unit (6) of the first battery module (3). [6] Arrangement according to claim 5, characterized by , that the battery modules (3) are contained within a frame (7). [7] Battery pack (1) with a housing (2) in which at least one battery module (3) according to one of claims 1 to 4 or at least an arrangement according to one of claims 5 or 6 is accommodated. [8] Battery pack (1) according to claim 7, in which at least one arrangement according to claim 6 is included, wherein the frame (7) receiving the battery modules (3) is arranged on a housing base (8). [9] Battery pack (1) according to one of claims 7 or 8, wherein a bottom battery module (3) is thermally insulated from a housing base (8). [10] Vehicle with a battery pack (1) according to any one of claims 7 to 9, wherein the battery pack (1) is connected to a drive system of the vehicle.

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