Assembly comprising an electrochemical element and an electrohydrodynamic pump, battery module, battery and associated process

Abstract

Assembly comprising an electrochemical element and an electrohydrodynamic pump, battery module, battery, and associated process. The assembly includes an electrochemical element (22) comprising a container (50) containing at least one cathode, at least one anode, and at least one internal separator interposed between each anode and each cathode. The container (50) has an external surface (26) intended to be immersed in a cooling fluid for the electrochemical element (22). The assembly includes at least one flat electrohydrodynamic pump (24) attached to the external surface (26) of the container (50). The electrohydrodynamic pump (24) is configured to generate a local displacement of the cooling fluid in contact with the electrohydrodynamic pump(s) (24) applied to the external surface (26) of the electrochemical element (22). Figure for the abbreviation: Figure 1

Description

Title of the invention: Assembly comprising an electrochemical element and an electrohydrodynamic pump, battery module, battery and associated method

[0001] The present invention relates to an assembly, comprising an electrochemical element including a container containing at least one cathode, at least one anode and at least one internal separator interposed between each anode and each cathode, the container having an external surface intended to be immersed in a cooling fluid for the electrochemical element.

[0002] Such an assembly is intended to be included in a battery module used particularly in electrical power supply applications in the automotive, rail, aeronautical, and space sectors, and / or for energy storage. The battery module comprising several electrochemical assemblies is particularly suited to high electrical power applications.

[0003] The ecological transition requires the use of batteries in which the electrical powers involved are increasingly higher, both when supplying a current and a voltage to a consumer system, or when recharging the battery module.

[0004] In this context, the battery module generally undergoes significant heating which requires efficient dissipation of the calories produced by Joule effect.

[0005] To efficiently cool the battery, it is known to immerse at least partially the battery elements of the module in a dielectric liquid which is circulated to pass around the battery elements and collect the heat they give off.

[0006] WO2020002254 describes a battery module of the aforementioned type, in which a fluid Cooling is circulated by an electrohydrodynamic pump. The electrochemical elements are spaced apart, defining large intermediate volumes. One or more electrohydrodynamic pumps in the form of grids are arranged in the intermediate volumes between the electrochemical elements, away from them.

[0007] Such a battery module is not entirely satisfactory. Indeed, the presence of a large intermediate volume between the electrochemical elements limits the volume available for storing electrical energy in the battery module. It is therefore not very compact.

[0008] Furthermore, the entrainment of the cooling fluid is significant at the electrohydrodynamic pumps, but diminishes away from them, particularly at the surface of the electrochemical elements. Localized heating of the electrochemical elements is therefore always likely to occur, despite the presence and circulation of the cooling fluid.

[0009] An object of the invention is therefore to have an assembly which offers a particularly compact arrangement in a battery module, in order to increase the energy density stored by the battery module, while ensuring very efficient and low energy consumption cooling of the electrochemical elements present in the battery module.

[0010] To this end, the invention relates to an assembly of the aforementioned type, characterized in that it comprises at least one flat electrohydrodynamic pump, attached to the external surface of the container, the or each electrohydrodynamic pump being configured to generate a local displacement of the cooling fluid in contact with the or each electrohydrodynamic pump applied to the external surface of the electrochemical element.

[0011] The assembly according to the invention may comprise one or more of the following features, taken individually or in any technically possible combination:

[0012] - the electrohydrodynamic pump comprises at least one pair of electrodes of a first polarity defining between them an intermediate space along the external surface, the electrohydrodynamic pump comprising, for each pair of electrodes of first polarity, an electrode of a second polarity opposite to the first polarity, interposed in the intermediate space between the electrodes of first polarity;

[0013] - the first polarity electrodes form parallel fingers, the electrode of second polarity forming an opposite finger arranged parallel and apart from the parallel fingers, the area of ​​each finger being different from the area of ​​the opposite finger;

[0014] - the electrohydrodynamic pump has a substrate carrying the electrodes of first and second polarities, the substrate being brought onto the external surface;

[0015] - the substrate is a plate with an area greater than the area of ​​the first and second electrodes second polarities or the substrate is a flexible band with a contour corresponding to the contour of the first and second polarity electrodes;

[0016] - it includes a separation system, the separation system defining at minus a cooling fluid circulation channel having a cooling fluid circulation axis;

[0017] - the separation system comprises a plurality of projecting wedges applied on the first and second polarity electrodes;

[0018] - the or each pair of first polarity electrodes and the or each electrode of second polarity locally delimits the one or each circulation channel in extending transversely with respect to the fluid flow axis;

[0019] - the separation system defines a plurality of parallel circulation channels cooling fluid, the electrohydrodynamic pump comprising a plurality of successive first polarity electrodes and a plurality of successive second polarity electrodes interposed between the first polarity electrodes, the first polarity electrodes and the second polarity electrodes extending transversely to the parallel channels, at successive positions along the circulation axis;

[0020] - the container is a prismatic container, a cylindrical container or is a poached.

[0021] The invention also relates to a battery module comprising a housing and a plurality of electrochemical assemblies arranged in the housing, the plurality of electrochemical assemblies comprising at least a first assembly as defined above.

[0022] The battery module according to the invention may comprise one or more of the following features, taken individually or in any technically possible combination:

[0023] - the plurality of electrochemical sets forms a stack, at least one second assembly of the stack being placed adjacent and opposite the first assembly by defining an intermediate channel for the circulation of cooling fluid, the intermediate channel being delimited on one side at least in part by the electrohydrodynamic pump of the first assembly and being delimited on another side at least in part by an uncovered region of an external surface of the electrochemical element of the second assembly;

[0024] - the second assembly is as defined above, the external surface of the element electrochemical of the second set having on the side opposite the first set, the exposed region and on an opposite side, at least one electrohydrodynamic pump placed opposite an exposed region of an external surface of an electrochemical element of a third set of the stack;

[0025] - it includes a transformer, electrically connected upstream to at least one electrochemical element of a set of the plurality of electrochemical sets and connected downstream to the electrohydrodynamic pump or pumps to electrically supply the electrohydrodynamic pump or pumps, advantageously with a voltage greater than 500 V, in particular between 500 V and 3000 V;

[0026] - it comprises a first row of terminals or connection tabs connected to the anodes of the electrochemical elements and a second row of terminals or connecting tabs connected to the cathodes of the electrochemical elements, the transformer being arranged between the rows of terminals or connecting tabs.

[0027] The invention also relates to a battery comprising at least one battery module as defined above and a cooling system, connected to the battery module housing.

[0028] The battery according to the invention may include the following feature:

[0029] - the cooling system includes a cooling circuit, connected to the battery module housing, the cooling circuit including at least one heat exchanger, a coolant collection line connecting the housing to the heat exchanger and a cooled coolant supply line connecting the heat exchanger to the housing.

[0030] The invention also relates to a method for cooling a battery module, comprising the following steps: - supply of cooling fluid, in particular a dielectric liquid, into the casing of a battery module as defined above; - bringing the cooling fluid into contact with the electrohydrodynamic pump of at least one assembly contained in the battery module; - electrical power supply for the electrohydrodynamic pump; - circulation of the cooling fluid by the electrohydrodynamic pump along the electrohydrodynamic pump applied to the external surface of the electrochemical element of the assembly.

[0031] The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings, in which:

[0032] - [Fig. 1] Fig. 1 is a schematic partial cross-sectional view of a first battery comprising a battery module according to the invention;

[0033] - [Fig.2] [Fig.2] is a (a) front (b) side (c) rear view of an electric pump trohydrodynamic applied to an external surface of an electrochemical element in an assembly according to the invention;

[0034] - [Fig.3] [Fig.3] is a schematic top view of a stack of sets electrochemicals according to the invention, in a battery module;

[0035] - [Fig.4] Fig.4 is a schematic view describing the operating principle of an electrohydrodynamic pump on the external surface of a battery element in an assembly according to the invention;

[0036] - [Fig. 5] [Fig. 5] is an elevational view of a battery module comprising a stacking of several electrochemical assemblies and a transformer to electrically power the electrohydrodynamic pumps attached to electrochemical elements of the battery module;

[0037] - [Fig.6] [Fig.6] is a view of an overall variant according to the invention comprising a prismatic electrochemical element; and

[0038] - [Fig.7] Fig.7 is a view of another overall variant according to the invention comprising a cylindrical electrochemical element.

[0039] A first battery 10 according to the invention is schematically illustrated in [Fig. 1]. The battery 10 comprises at least one battery module 12, and a cooling fluid circulation circuit 14 for cooling the battery module 12.

[0040] The battery module 12 comprises a housing 16, delimiting an internal volume 18. It further comprises a stack 20, received in the internal volume 18, comprising a plurality of electrochemical elements 22. At least a part of the electrochemical elements 22, preferably all the electrochemical elements 22 are provided with an electrohydrodynamic pump 24 on their external surface 26 and thus form electrochemical elements according to the invention.

[0041] In this example, the battery module 12 further includes a transformer 44 (see [Fig.5]) for supplying each electrohydrodynamic pump 24 with the electrochemical elements 22.

[0042] Still with reference to [Fig.5], the battery module 12 further comprises an electrical connection system 46 for the electrochemical elements 22 to connect them to electrical terminals (not shown) of the battery module 12, and advantageously, an electronic management system 48, interposed on the electrical connection system 46 between the electrochemical elements 22 and the terminals of the battery module 12.

[0043] In the example of [Fig.1], the case 16 comprises a base 28, side walls 30, and a cover 32 which define the internal volume 18.

[0044] The housing 16 defines an inlet 34 for supplying a cooling fluid intended to be heated by heat exchange with the electrochemical elements 22, and an outlet 36 for discharging the heated cooling fluid. The cooling fluid is preferably a dielectric liquid.

[0045] The dielectric liquid advantageously has a resistivity greater than 50 GQ and a breakdown voltage greater than 40 kV for an air gap of 2.5 mm, preferably between 45 kV and 55 kV for an air gap of 2.5 mm.

[0046] The dielectric liquid furthermore has a density advantageously less than 1, for example between 0.7 and 0.9 and a low viscosity, for example less than 3.3 mPa.s at 25 °C, as measured by ASTM D7042.

[0047] In this example, the stack 20 extends along an axis AA' parallel to the bottom 28 of the internal volume 18 of the housing 16 when it is received in the internal volume 18. The axis A-A' is horizontal here.

[0048] The stack 20 comprises in particular more than two electrochemical sets, preferably between 2 and 20 stacked electrochemical sets. In this example, each set in the stack 20 comprises an electrochemical element 22 (sometimes referred to as an "electrochemical cell") and an electrohydrodynamic pump 24 on its external surface 26

[0049] As seen in [Fig.3], the stack 20 further comprises a system 40 for separating the electrochemical elements 22 from adjacent electrochemical sets, defining channels 42 for circulating cooling fluid between each pair of adjacent electrochemical sets, and a mechanical holding system (not shown) for the stack 20, suitable for keeping the electrochemical sets and the separation system 40 stacked as a single block.

[0050] With reference to Figures 1 and 3, each electrochemical element 22 comprises a container 50, defining the external surface 26, and, in the internal volume defined by the container 50, an alternation of anodes, internal separators, and cathodes (not shown).

[0051] As can be seen in [Fig.5], the electrochemical element 22 further comprises at least one anode connection tab 52, and at least one opposite cathode connection tab 54.

[0052] In the example shown in Figures 1 to 5, the container 50 is formed by a pouch, advantageously deformable to the touch. In the variants of [Fig. 6] and [Fig. 7], which will be described later, the container 50 is prismatic or cylindrical respectively and is generally non-deformable to the touch.

[0053] The pocket is formed, for example, of two multilayer films welded together at their edges. Each multilayer film comprises a metallic layer, generally made of aluminum, sandwiched between two layers of plastic material.

[0054] The container 50 thus constituted receives anodes and cathodes each separated by an internal separator, an electrolyte, and is sealed in a hermetically sealed manner.

[0055] The electrochemical element 22 is for example of the lithium-ion type.

[0056] In the example shown in Figures 1 to 5, the container 50 has a shape generally prismatic. The external surface 26 thus has a main front face 56, on which the electrohydrodynamic pump 24 is mounted, and a main rear face 58 defining at least one exposed region 60, intended to be swept by circulating cooling fluid. The main faces 56, 58 are connected laterally to each other at their peripheries.

[0057] Each tab 52, 54 protrudes from the container 50, on either side of the container 50 with respect to a median axial plane. Thus, all the tabs 52 connected to the anodes protrude on the same side of the container 50, and all the opposite tabs 54 connected to the cathodes protrude on the other side of the container 50.

[0058] The tabs 52, 54 are connected to the electrical connection system 46, by example by welding.

[0059] According to the invention, at least a part of the electrochemical elements 22 of the stack 20, preferably each electrochemical element 22 of the stack 20, is provided, on its main front face 56, with a flat electrohydrodynamic pump 24 applied to the main face 56 by being fixed thereto.

[0060] The electrohydrodynamic pump 24 is planar, in that it has a thickness less than the thickness of each electrochemical element 22, taken along the axis AA' between the main front face 56 and the main rear face 58.

[0061] The thickness of each electrohydrodynamic pump 24 is for example less than 2 mm.

[0062] In the example shown in [Fig.2], the electrohydrodynamic pump 24 comprises a substrate 70, and an alternation of electrodes of a first polarity 72 and electrodes of a second polarity 74 formed on the substrate 70. Each electrode of second polarity 74 is interposed between a pair 76 of electrodes of first polarity 72.

[0063] The electrohydrodynamic pump 24 further includes a common path 78 for supplying power to the first polarity electrodes 72, and a common path 80 for supplying power to the second polarity electrodes 74.

[0064] The substrate 70 here has an identical or homothetic contour to that of the main front face 56 on which it is fixed.

[0065] Its area is for example between 50% and 100% of the area of ​​the main front face 56, taken perpendicular to the axis A-A'.

[0066] In the example of [Fig.2], the substrate 70 also has an area greater than the area occupied by the electrodes 72, 74 and by the feed paths 78, 80 on the substrate.

[0067] In an alternative (not shown), the substrate 70 has a shape identical or homothetic to that of the electrodes 72, 74 and the feed paths 78, 80.

[0068] The substrate 70 is, for example, formed of a plate of electrically insulating material, in particular plastic. The plate is, for example, formed of a fluoropolymer, in particular polytetrafluoroethylene, or of a ceramic.

[0069] An electrically insulating material generally has a resistivity greater than 1015 ohm.m measured according to Standard NF EN 62631-1.

[0070] The substrate 70 generally has a low electrical permittivity, in particular less than 5, measured according to Standard IEC 62631-2-1:2018. This avoids electrical breakdown phenomena at the surface of the material.

[0071] In this case, the thickness of the substrate 70 is advantageously less than 2 mm.

[0072] Alternatively, the substrate 70 consists of a deformable strip, in particular of the "Flex" type. It comprises a thin layer of a flexible polymer. touch, in particular a polyimide, such as Kapton®, on which electrodes 72, 74 are deposited.

[0073] In this case, the thickness of the substrate 70 is advantageously less than 0.5 mm.

[0074] As illustrated by [Fig.2], the electrodes 72, 74, and the feed paths 78, 80 are arranged on a first face 81A of the substrate 70, a second face 81B of the substrate 70 remaining without electrodes 72, 74 and feed paths 78, 80.

[0075] The second face 81B of the substrate is fixed to the main front face 56 of the electrochemical element 22.

[0076] Alternatively, the electrohydrodynamic pump 24 is substrate-free. The electrodes 72, 74 and the supply paths 78, 80 are applied directly to the external surface 26, which is then electrically insulating.

[0077] The electrodes 72, 74, and the feed paths 78, 80 are formed of a metallic layer, for example containing copper or aluminum and / or alloys of these metals. The metallic layer is generally less than 500 micrometers thick.

[0078] In the example shown in Figures 1 to 5, the first polarity electrodes 72 extend perpendicularly to an elevation axis BB' of the substrate 70 and the main front face 56 of the electrochemical element 22, along the width of the electrochemical element 22, substantially horizontally on the [Fig.2].

[0079] The first polarity electrodes 72 are formed by fingers 82 projecting parallel to each other. Each finger 82 extends from the feed path 78 of the first polarity electrodes 72 to the feed path 80 of the second polarity electrodes 74, to a free end disposed opposite and away from the feed path 80 of the second polarity electrodes 74.

[0080] The adjacent parallel fingers 82 delimit between themselves an intermediate space 84 in which a second polarity electrode 74 is received.

[0081] Each second polarity electrode 74 also extends perpendicularly to the elevation axis B-B', parallel to the first polarity electrodes 72.

[0082] The second polarity electrodes 74 are also formed by opposing fingers 86 protruding parallel to each other, each opposing finger 86 being interposed between two fingers 82 in the intermediate space 84.

[0083] Each opposite finger 86 extends from the feed path 80 of the second polarity electrodes 74 to the feed path 78 of the first polarity electrodes 72, to a free end disposed opposite and away from the feed path 78 of the first polarity electrodes 72.

[0084] Along the elevation axis B-B', the height of the first polarity electrodes 72 (corresponding here to the width of the fingers 82) is different from the height of the second polarity electrodes 74 (corresponding to the width of the opposite fingers 86).

[0085] For example, the second polarity electrodes 74 have a height less than that of the first polarity electrodes 72, in particular less than 50% of the height of the first polarity electrodes 72, the heights being taken parallel to the elevation axis B-B'.

[0086] The transverse extent of the electrodes 72, 74, taken perpendicular to the elevation axis BB' between the feed path 78, 80 from which they protrude and their free end is greater than 50%, in particular greater than 60% of the width of the substrate 70 and / or the width of the main front face 56, taken perpendicular to the elevation axis B-B'.

[0087] The paths 78, 80 extend respectively along the lateral edges of the substrate 70, in the vicinity of the lateral edges of the main front face 56. They generally extend parallel to the elevation axis B-B'. They have a respective upper end 88, 90 for connection to a respective terminal of the transformer 44.

[0088] With reference to [Fig. 4], when the connection points 88, 90 are energized, in particular by applying an electrical voltage greater than 500 V between these points 88, 90, an electric field is created between each first-polarity electrode 72 and the adjacent second-polarity electrode 74 along the axis B-B'. This electric field causes the molecules of the dielectric liquid to dissociate into anions and cations.

[0089] Due to the different surfaces of the electrodes 72, 74 along the axis B-B', the anions and cations accumulate in different quantities on the respective electrodes 72, 74 and a flow F of liquid is generated along the elevation axis B-B' to compensate for the imbalance of charges.

[0090] In an advantageous embodiment, shown in [Fig.5], each electrohydrodynamic pump 24 is electrically powered by one or more electrochemical elements 22 of the battery module 12.

[0091] In this case, the transformer 44 is connected upstream to the tabs 52, 54 of at least one electrochemical element 22, preferably of several electrochemical elements 22 of the battery module 12.

[0092] The transformer 44 is connected downstream to the connection points 88, 90 on each electrohydrodynamic pump 24.

[0093] The transformer 44 is configured to increase the electrical voltage received between the tabs 52, 54 of the electrochemical elements 22 and to provide an electrical voltage between the connection points 88, 90 which is greater than 500 V, and in particular between 500V and 3000 V.

[0094] In the example illustrated in [Fig. 5], the tabs 52 connected to the anodes are arranged on one side of the electrochemical elements 22 of the stack 20, and the opposite tabs 54 connected to the cathodes are arranged on the other side of the electrochemical elements 22 of the stack-up 20.

[0095] The tabs 52, 54 delimit between each other an intermediate space 92 in which the transformer 44 is placed. This optimizes the available space within the battery module 12.

[0096] With reference to [Fig.3], the separation system 40 comprises a plurality of wedges 100, applied to the electrohydrodynamic pump 24 of an assembly to interpose between the electrodynamic pump 24 of the assembly and a main rear face 58 of an electrochemical element 22 of an assembly adjacent to the assembly carrying the electrohydrodynamic pump 24.

[0097] In the example shown in [Fig.3], each assembly is equipped with a plurality of parallel 100 wedges, fixed on the electrohydrodynamic pump 24.

[0098] Each wedge 100 is made of a rigid, non-compressible material, for example of fluorinated polymer, in particular polytetrafluoroethylene, or even ceramic.

[0099] Each 100 wedge is made of an electrically insulating material which generally has a resistivity greater than 1015 ohm.m measured according to Standard NF EN 62631-1.

[0100] Each 100 shim generally has a low electrical permittivity, in particular less than 5, measured according to Standard IEC 62631-2-1:2018. This avoids electrical breakdown phenomena on the surface of the material.

[0101] Each wedge 100 also has a compressive rigidity that allows it to withstand a compressive force within the stack 20 without significant deformation.

[0102] The Young's modulus of the material forming each wedge 100 is notably greater than 2000 MPa, as measured by Standard NF EN 12390-13.

[0103] The wedges 100 extend parallel to the elevation axis B-B', spaced apart from each other.

[0104] The spacing between two adjacent shims 100 is generally less than the width of a shim 100, taken perpendicular to the elevation axis B-B'. For example, the spacing between two shims 100 is less than 5 mm, in particular less than 3 mm.

[0105] The thickness of each wedge 100, taken along the stacking axis AA', is generally less than or equal to the thickness of an electrochemical element 22. This thickness is generally less than 2 mm and is between 0.5 mm and 1 mm.

[0106] As illustrated by the enlargement shown on the right in [Fig.3], each pair of adjacent wedges 100 defines between them a channel 42 for the circulation of cooling fluid.

[0107] The channel 42 is laterally delimited by the opposite lateral edges facing the two adjacent wedges 100. It is also delimited on one side by the electrohydrodynamic pump 24 of the assembly, in particular partly by the electrodes 72, 74 of the electrodynamic pump 24, and on the other hand, an uncovered region 60 of the main rear face 58 of an electrochemical element 22 of an assembly adjacent to the assembly carrying the electrohydrodynamic pump 24.

[0108] As shown in [Fig.4], the electrodes 72, 74 extend successively perpendicular to the axis of the channel 42, with an alternation of first polarity electrodes 72 and second polarity electrodes 74.

[0109] Thus, each channel 42 is delimited along its entire height along the axis BB' by a succession of first polarity electrodes 72 and second polarity electrodes 74.

[0110] The holding system (not shown) has for example one or more tie rods and end plates allowing the stack 20 of electrochemical assemblies stacked against each other in succession to be held together by means of the wedges 100.

[0111] Thus, in the stack 20 held mechanically by the holding system, each electrochemical element 22 of an assembly has, fixed on its main front face 56, an electrohydrodynamic pump 24, on which are fixed wedges 100, which are in contact with the main rear face 58 of an electrochemical element 22 of an adjacent assembly or of a terminal plate.

[0112] The electrochemical element 22 of the assembly receives support, on its main rear face 58, from the shims 100 of an electrochemical element 22 of another adjacent assembly and / or of a terminal plate.

[0113] Each pair of opposing electrochemical assemblies defines, between the wedges 100, the electrohydrodynamic pump 24, and the exposed region 60, a plurality of cooling fluid circulation channels 42 extending here parallel to the elevation axis B-B'.

[0114] With reference to [Fig.5], the electrical connection system 46 connects, on the one hand, the tabs 52 and, on the other hand, the tabs 54 to the electronic management system 48. The electronic management system 48 is itself connected to the terminals (not shown) of the battery module 12.

[0115] The electronic management system 48 includes electronic components for controlling the voltage and / or current delivered by each electrochemical element 22 of the battery module 12 during its discharge, and the voltage and / or current received by each electrochemical element 22 of the battery module 12 during its recharge.

[0116] With reference to [Fig. 1], the cooling fluid circulation circuit 14 comprises a heat exchanger 110, disposed outside the housing 16 of the battery module 12, a collection conduit 112 for the cooling fluid to be cooled connecting the outlet 36 to an inlet of the heat exchanger 110, and a conduit 114 of supply of cooled cooling fluid to housing 16, connecting an outlet of heat exchanger 110 to inlet 34 of housing 16.

[0117] The assembly of the battery module 12 will now be described.

[0118] Initially, each assembly is assembled by fixing, on an electrochemical element 22, an electrohydrodynamic pump 24 on the main front face 56 of the container 50 of the electrochemical element 22.

[0119] Then, the wedges 100 of the separation system 40 are fixed on the electrohydrodynamic pump 24, creating gaps for the formation of the channels 42.

[0120] Next, the electrochemical assemblies, each comprising an electrochemical element 22 and an electrohydrodynamic pump 24 assembled on the electrochemical element 22, are stacked one on top of the other, with the wedges 100 interposed.

[0121] The cooling fluid circulation channels 42 are then closed on one side by the electrohydrodynamic pump 24 carried by an electrochemical element 22 of an assembly and on the other side by the uncovered region 60 of the rear main face 58 of an electrochemical element 22 of an adjacent assembly.

[0122] The support system is then put in place to mechanically hold the stack 20 which can then be moved as a single unit.

[0123] The stack 20 is then inserted into the internal volume 18 of the housing 16. It is then immersed in a cooling fluid, in particular a dielectric fluid. The housing 16 is closed and connected to the fluid circulation circuit 14.

[0124] The use of the battery 10 will now be described. During use, electrical power is delivered by the electrochemical elements 22 to the terminals of the battery module 12, during discharge, or is delivered to the electrochemical elements 22 through the terminals of the battery module 12 during charge.

[0125] During discharge or recharge, cooling fluid is routed through the circulation circuit 14, in order to supply cooled cooling fluid into the internal volume 18 through the inlet 34.

[0126] The cooling fluid is carried through the channels 42 located between the electrochemical elements 22.

[0127] For this purpose, each electrohydrodynamic pump 24 is activated. The connection points 88, 90 are supplied by the transformer 44 to apply an electrical voltage greater than 500 V between these points.

[0128] This electrical voltage is applied between each first polarity electrode 72 and each adjacent second polarity electrode 74.

[0129] It causes a separation of molecules of the dielectric liquid into anions and cations. The cations accumulate on the negatively polarized electrodes, while the Anions accumulate on the positive polarity electrodes.

[0130] Given the difference in area between electrodes 72, 74, there is an imbalance between the charges accumulated on each electrode 72, 74, this imbalance causing fluid pumping.

[0131] Local turbulence is created in each channel 42 along the electrodynamic pump 24 along the elevation axis B-B'. This turbulence is created in the vicinity of a pair of electrodes 72, 74 where the pumping takes place. The pumping locally generates turbulence in the flow which has the effect of improving heat transfer, in particular on the exposed region 60 on each rear principal face 58 delimiting a channel 42.

[0132] As a result, the heat exchange at the level of the exposed region 60 is improved, causing a more efficient evacuation of the heat emitted in the electrochemical element 22, in particular by thermal convection between the exposed region 60 and the cooling fluid present in the channel 42.

[0133] The heated cooling fluid from the channels 42 is then collected at the outlet 36 to be conveyed to the heat exchanger 110 via the collection line 112.

[0134] Thus, the use of flat electrohydrodynamic pumps 24 applied to the external surface 26 of the container 50 significantly increases the heat exchange between the cooling fluid and the electrochemical elements 22, providing very efficient cooling of these electrochemical elements 22. It also makes it possible to either eliminate or minimize the need for an external pump on the circulation circuit 14.

[0135] This cooling efficiency is achieved by maintaining a very compact architecture of the battery module 12, since the electrochemical elements 22 are stacked one on top of the other, the electrohydrodynamic pump 24 occupying minimal space in the internal volume 18 of the housing 16.

[0136] A beneficial effect is obtained by improved heat dissipation in the electrochemical elements 22, which allows them to be brought closer together in order to increase the energy density present in the battery 10 by limiting, or even eliminating, the risk of heating within the battery module 12.

[0137] Very low electrical consumption (for example less than 1 mW per electrohydrodynamic pump 24) is required to obtain this efficient cooling, since the electrohydrodynamic pumps 24 are low power consumers.

[0138] The electrical power required for the operation of the electrohydrodynamic pumps 24 is advantageously supplied directly by the electrochemical elements 22 of the battery module 12, in particular by providing a transformer 44 which can be compactly integrated into the battery module 12.

[0139] Thus, the battery module 12 exhibits better cooling performance, compared with air cooling.

[0140] The electrical consumption of the cooling system is low, particularly compared to an air-cooling system, and noise emission is very low. The electrochemical components 22 are better protected, since no oxidation of the outer containers 50 occurs as a result of the airflow.

[0141] Cooling is integrated into the battery module 12, which simplifies the circuit and increases reliability. Furthermore, the use of electrohydrodynamic pumps 24 without moving components ensures high reliability and reduced maintenance, while offering a very compact design.

[0142] In one variant (not shown), the separation system 40 is not formed by wedges 100, but by another device defining at least one open channel for the circulation of the dielectric fluid. The device is electrically insulating and exhibits mechanical resistance to compression in the stack 20.

[0143] In another embodiment, shown schematically in [Fig. 6], the electrochemical element 22 is a prismatic element. It comprises a rigid container 50, to which the electrohydrodynamic pump 24 is attached to form an assembly according to the invention.

[0144] In this example, the first polarity electrodes 72 and the second polarity electrodes 74 are mounted parallel to each other and parallel to the elevation axis B-B'.

[0145] On the contrary, the wedges 100 are mounted perpendicular to the axis B-B'. The channels 42 thus extend perpendicularly to the elevation axis B-B', horizontally on the [Fig.6],

[0146] The operation of the battery module 12 comprising electrochemical assemblies as shown in [Fig.6] is otherwise analogous to that of the battery module 12 described previously in Figures 1 to 5.

[0147] In another embodiment, shown in [Fig. 7], the electrochemical element 22 is cylindrical in shape. The electrodynamic pump 24 is wound around the cylindrical external surface 26 of the container 50 to form an assembly according to the invention.

[0148] The presence of the electrohydrodynamic pump 24 around the cylindrical electrochemical element 22 improves heat exchange at the external surface 26, increasing the cooling provided by the cooling fluid.

Claims

Demands

1. Assembly, comprising an electrochemical element (22) comprising a container (50) containing at least one cathode, at least one anode and at least one internal separator interposed between each anode and each cathode, the container (50) having an external surface (26) intended to be immersed in a cooling fluid of the electrochemical element (22); characterized in that the assembly comprises at least one flat electrohydrodynamic pump (24), attached to the external surface (26) of the container (50), the or each electrohydrodynamic pump (24) being configured to generate a local displacement of the cooling fluid in contact with the or each electrohydrodynamic pump (24) applied to the external surface (26) of the electrochemical element (22).

2. Assembly according to claim 1, wherein the electrohydrodynamic pump (24) comprises at least one pair (76) of electrodes of a first polarity (72) defining between them an intermediate space (84) along the external surface (26), the electrohydrodynamic pump (24) comprising, for the or each pair (76) of electrodes of first polarity (72), an electrode of a second polarity (74) opposite to the first polarity, interposed in the intermediate space (84) between the electrodes of first polarity (72).

3. Assembly according to claim 2, wherein the first polarity electrodes (72) form parallel fingers (82), the second polarity electrode (74) forming an opposite finger (86) arranged parallel and apart from the parallel fingers (82), the area of ​​each finger (82) being different from the area of ​​the opposite finger (86).

4. Assembly according to any one of claims 2 or 3, wherein the electrohydrodynamic pump (24) has a substrate (70) carrying the electrodes (72, 74) of first and second polarities, the substrate (70) being attached to the external surface (26).

5. Assembly according to claim 4, wherein the substrate (70) is a plate with an area greater than that of first and second polarity electrodes (72, 74) or wherein the substrate (70) is a flexible band with a contour corresponding to the contour of the first and second polarity electrodes (72, 74).

6. Assembly according to any one of claims 2 to 5, comprising a separation system (40), the separation system (40) defining at least one cooling fluid circulation channel (42) having a cooling fluid circulation axis.

7. Assembly according to claim 6, wherein the separation system (40) comprises a plurality of protruding wedges (100) applied to the first and second polarity electrodes (72, 74).

8. Assembly according to claim 6 or 7, wherein the pair or pairs of first-polarity electrodes (72) and the electrode or pairs of second-polarity electrodes (74) locally delimit the flow channel or channels (42) by extending transversely with respect to the fluid flow axis

9. Assembly according to any one of claims 6 to 8, wherein the separation system (40) defines a plurality of parallel channels (42) for circulating cooling fluid, the electrohydrodynamic pump (24) comprising a plurality of successive first-polarity electrodes (72) and a plurality of successive second-polarity electrodes (74) interposed between the first-polarity electrodes (72), the first-polarity electrodes (72) and the second-polarity electrodes (74) extending transversely across the parallel channels (42), at successive positions along the circulation axis.

10. Assembly according to any one of the preceding claims, wherein the container (50) is a prismatic container, a cylindrical container or is a pocket.

11. Battery module (12), comprising a housing (16) and a plurality of electrochemical assemblies arranged in the housing (16), the plurality of electrochemical assemblies comprising at least a first assembly according to any one of the preceding claims.

12. Battery module (12) according to claim 11, wherein the plurality of electrochemical assemblies form a stack (20), at least a second assembly of the stack (20) being placed adjacent and opposite the first assembly by defining an intermediate channel (42) for the circulation of cooling fluid, the intermediate channel (42) being delimited on one side at least in part by the electrohydrodynamic pump (24) of the first assembly and being delimited on another side at least in part by an uncovered region (60) of an external surface (26) of the electrochemical element (22) of the second assembly.

13. Battery module (12) according to claim 12, wherein the second assembly is according to any one of claims 1 to 10, the external surface (26) of the electrochemical element (22) of the second assembly having on the side facing the first assembly, the exposed region (60) and on an opposite side, at least one electrohydrodynamic pump (24) placed facing an exposed region (60) of an external surface (26) of an electrochemical element (22) of a third assembly of the stack (20).

14. Battery module (12) according to any one of claims 12 to 13, comprising a transformer (44), electrically connected upstream to at least one electrochemical element (22) of a plurality of electrochemical assemblies and connected downstream to the electrohydrodynamic pump or each electrohydrodynamic pump (24) to electrically supply the electrohydrodynamic pump or each electrohydrodynamic pump (24), advantageously with a voltage greater than 500 V, in particular between 500 V and 3000 V.

15. Module according to claim 14, wherein the stack (20) comprises a first row of terminals or connecting tabs (52) connected to the anodes of the electrochemical elements (22) and a second row of terminals or connecting tabs (54) connected to the cathodes of the electrochemical elements (22), the transformer (44) being disposed between the rows of terminals or connecting tabs (52, 54).

16. Battery (10) comprising at least one battery module (12) according to any one of claims 11 to 15 and a cooling system, connected to the housing (16) of the battery module (12).

17. Battery (10) according to claim 16, wherein the cooling system comprises a cooling circuit (14), connected to the housing (16) of the battery module (12), the cooling circuit (14) comprising at least one heat exchanger (110), a coolant collection conduit (112) connecting the housing (16) to the heat exchanger (110) and a cooled coolant supply conduit (114) connecting the heat exchanger (110) to the housing (16).

18. A method for cooling a battery module (12), comprising the following steps: - supplying cooling fluid, in particular a dielectric liquid, into the casing (16) of a battery module (12) according to any one of claims 11 to 15; bringing the cooling fluid into contact with the electrohydrodynamic pump (24) of at least one assembly contained in the battery module (12); power supply of the electrohydrodynamic pump (24); circulation of the cooling fluid by the electrohydrodynamic pump (24) along the electrohydrodynamic pump (24) applied to the external surface (26) of the electrochemical element (22) of the assembly.

Images