FR3022402A1 - MODULAR ELECTRICAL BATTERY COMPRISING A THERMAL PROTECTION AND CONTROL DEVICE - Google Patents

Abstract

The invention relates to an improved modular electric battery incorporating thermal regulation and mechanical protection functions. The battery comprises: a set of rechargeable cells (100) electrically connected together, arranged to form at least one plate (101) comprising at least one first face (101a) having means for electrical connection (110) between cells, ○ a thermal protection and regulation device comprising at least one joint of both electrical insulating material and thermal conductor (120) interposed between the electrical connection means (110) of the first face and a thermal collector comprising at least one plate thermally conductive material (130) in contact with the seal, ○ a housing (140) containing at least the cell assembly and having at least one thermally conductive wall (142) in contact with the plate.

Description

FIELD OF THE INVENTION The present invention relates to the field of modular electric batteries (or battery packs), in particular the thermal regulation of rechargeable modular electric batteries.

Background The use of battery packs as reversible sources of power and power in portable applications is common, and is becoming more common in traction applications and stationary applications. In these applications where high voltage levels and high capacities are required, the battery packs are generally formed of modules, connected together in series and / or in parallel depending on the intended application. Each module integrates a plurality of elementary cells, which are electrochemical cells for storing and restoring electrical energy, connected in series and / or in parallel by appropriate connections to the current flow. A modular electric battery architecture, where compact modules of intermediate size individually constitute a source of energy and power, is conventionally used because it provides flexibility for the arrangement, use and maintenance of the modules.

Certain functions of the battery pack such as thermal regulation, mechanical protection and safety for the reversible storage of electrical energy must then be taken into account and ensured at the level of the battery module. At present, various rechargeable battery technologies, also known as secondary batteries, for the reversible storage of electrical energy in electrochemical form, are used for applications associated with electric traction of vehicles or with stationary energies. Among these, Li-ion batteries are widely studied. A battery module must be thermally regulated in particular because the charging and discharging of the cells cause temperature rises, in particular due to the internal resistance of the cells and to that of the connectors connecting the cells. However, a battery must operate in a limited temperature range, including Li-ion batteries, in order firstly to prevent any risk of thermal runaway of the cells, and secondly to limit the aging phenomena of the cells, that affect module performance and require increased maintenance. Various undesirable phenomena may occur if one or more cells of a battery pack are outside the ranges of temperature and / or voltage recommended by the manufacturer. These phenomena can be caused by a hot spot locally and / or overload, but also by mechanical damage to the cells, such as perforation, or contact on the connectors causing a short circuit.

Depending on the chemistry of the accumulator, these phenomena will irreversibly damage the active materials, reduce the cell capacity, render the system inoperative or even cause a thermal runaway with fire risks and / or gassing. For Li-ion batteries, "passive" safety systems are integrated in the design of each element (separator capable of irreversibly cutting the flow of electrolyte between the electrodes, gas compartment and vent to prevent the rise in pressure, etc.) to reduce the risk of thermal runaway. Specific electronics can also be integrated into the cell, with the same purpose. At the level of the module or the pack, the Battery Management System (BMS) in English terms must ensure safe operation under normal use and limit the risks of misuse. Or the possibilities of mechanical damage to a pack are multiple, given the versatility of use, especially in a vehicle. If external mechanical protection is commonly used, the BMS seems powerless to avoid a short circuit initiated on the connectors and the associated heat propagation via connectors. Mechanical protection of the module is therefore also important to reduce the risk of damage by short circuit, induced for example during a shock which leads to the perforation of a cell or when an electrically conductive component comes into contact with the connectors.

Taking into account the module-level thermal control and mechanical protection functions in a modular electric battery makes it possible to improve its safety.

Many cooling techniques and various modular battery architectures exist. The patent application US 2013/0089768 A1 for example describes a battery pack in which thermal conductor inserts are slid between cylindrical cells parallel to their axes, and are fixed to the package housing by at least one end. These inserts dissipate the heat captured by direct contact with the lateral faces of the cells towards the outside of the battery pack. However, the heat conducted and dissipated by the connectors is not drained to the outside, at the risk of generating hot spots in the module, and no precaution is taken as to the risk of propagation by the connectors of the heat generated. by a short circuit from one cell to another. Patent application WO 2012/136439 A1 describes a modular battery comprising a stack of cells in which at least one cooling element is inserted between two adjacent prismatic cells in the stack. The cooling element has a thermo-conductive section located between the cells and a cooling section that projects laterally out of the stack. However, the heat collected and dissipated by the connectors is not drained to the outside, thus risking generating hot spots conducive to thermal runaway and temperature gradients within the cell conducive to aging. In addition, the structure of the battery module appears protruding rather than compact, which is not desirable for the arrangement of the modules of a modular pack in a confined space. US Patent Application 2012/0034499 A1 discloses a modular battery in which a thermal band having high thermal and electrical conduction properties, is connected between the terminal of a first cell and the terminal of a second cell, and is connected to the wall of the battery case having a high thermal conductivity by a thermal bridge device characterized by its electrical insulation. However, no precaution is taken as to the risks of occurrence of short-circuit and short-circuit propagation at the level of connectors, including heat propagation from one cell to another. Patent Application EP 2,530,778 A1 describes another example of a modular battery in which an active heat dissipation is carried out by a ventilation system internal to or external to the battery, or by a system for circulating a cooling fluid. . The battery comprises a set of thermal insulating and electrical insulating inserts, attached to a heat sink base, slid between cylindrical cells parallel to their axes, which individually seal the cells at the side and bottom faces. These inserts capture the heat released by direct contact with the side faces of the cells and lead to the heat sink which is ventilated by a ventilation system internal or external to the battery, or which is in contact with a heat exchanger. This type of battery, specific to cylindrical rechargeable batteries, has the main disadvantage of being based on an active dissipation of heat, requiring energy. On the other hand the system has a complex structure, comprising various composite elements nested in each other. OBJECTS AND SUMMARY OF THE INVENTION The object of the present invention is to overcome at least in part the above-mentioned problems of the prior art, and generally aims at providing a modular safety battery improved in terms of security by combined integration. thermal control functions and mechanical protection of the battery. The present invention aims in particular to provide a modular battery which can both be thermally regulated without requiring a specific energy input for this thermal regulation, so as to prevent any risk of thermal runaway of the cells and to limit the cell aging phenomena, and in which the risks of damage to the battery by occurrence and short-circuit propagation that can be caused mechanically, particularly at the level of connectors, are limited. The present invention is well suited to the traction of electric vehicles, especially electric vehicles in which the solicitations of the batteries are very important and may cause a thermal runaway linked to an "abusive" use, going beyond the normal use, or linked to mechanical damage. Thus, to achieve at least one of the aforementioned objectives, among others, the present invention proposes, in a first aspect, a modular electric battery comprising: a set of electrochemical cells for storing and restoring electrical energy electrically connected to each other, each cell having a positive terminal and a negative terminal, the cells being arranged next to one another to form at least one plate comprising at least a first face having electrical connection means between the cells; a thermal protection and regulation device comprising at least one joint of material both electrical insulator and thermal conductor interposed between said electrical connection means of said first face and a thermal collector comprising at least one plate of thermally conductive material in contact with said seal, a housing containing at least said set emble of cells and having at least one thermally conductive wall in contact with said plate. According to one embodiment, the battery comprises at least two trays of 20 cells, arranged opposite one another by a second face, opposite to said first face having connection means. According to one embodiment, the battery may comprise at least one rod of thermally conductive material attached at both ends to said plates of each of the two plates, said rod being inserted between the cells. The casing may then comprise a single thermally conductive wall in contact with a single plate of the collector, so as to develop a contact surface such that the heat of all the cells is dissipated and discharged to the outside of the battery. passive way. Advantageously, the battery comprises at least one intermediate plate 30 disposed between said two plates, and comprising a thermal protection and regulation device similar to the other plates, said at least one rod of thermally conductive material being furthermore fixed to the plate of the plate intermediate. A plurality of rods may be distributed between the cells, each rod preferably being disposed between four adjacent cells located in two rows of cells of a same tray, the set of rods preferably comprising between 2 and (n1) x (m -1) stems, where n is the number of cells per row of a plate and m is the number of rows of the same plate. According to one embodiment, the cells are cylindrical in shape, preferably each having their positive terminal and their negative terminal on two opposite sides of the cell. Alternatively, the electrochemical cells are prismatic cells, each having their positive terminal and their negative terminal on the same face of the cell. Preferably, the cells are of Li-ion type. Advantageously, the plate is formed of one or more thermally conductive materials, preferably metal and / or composite material comprising thermally conductive fillers. The seal may be in a discontinuous form and constituted by a set of lamellae. The seal may also be in the form of a continuous carpet. Advantageously, the thermally conductive wall of the housing is made of plastic or composite material preferably comprising one or more thermoplastic polymers of the polylactic acid, acrylonitrile-butadiene-styrene or nylon type. The thermally conductive wall of the housing may also be metal, preferably aluminum. The present invention also relates to an electric or hybrid vehicle comprising a battery according to the invention. Other objects and advantages of the invention will appear on reading the following description of examples of particular embodiments of the invention, given by way of non-limiting examples, the description being made with reference to the appended figures described. below. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a schematic cross section of a modular battery according to a first embodiment of the invention. Figure 2 is a schematic cross section of a modular battery according to a second embodiment of the invention.

FIG. 3 is a schematic top view of a modular battery according to the second embodiment of the invention illustrated in FIG. 2. FIG. 4 is a schematic cross section of a modular battery according to a variant of the second embodiment of FIG. embodiment of the invention, comprising three trays of cells. Figures 5 and 6 shows the thermal elevation in modular batteries according to the prior art. Figure 7 shows the thermal elevation in a modular battery according to the invention. In the figures, the same references designate identical or similar elements. DESCRIPTION OF THE INVENTION The object of the invention is to propose a modular battery comprising a thermal regulation device by passive dissipation of the heat and mechanical protection of the battery, making it possible to improve the safety of use of the battery. drums. By a passive heat dissipation device, it is meant a device that does not require an energy consuming system, particularly electricity, for its operation, as opposed to active heat dissipating devices such as ventilation systems. air using ventilators or heat transfer fluid circulation systems with pump (heat exchanger). In the present description, reference will be made indifferently to the term modular battery or modular electric battery or battery pack, to designate an electric battery comprising at least one module formed of a housing and incorporating a plurality of elementary cells or elements, connected in series and / or in parallel with a suitable connection to the current flow. The term connector and the term electrical connection means have the same meaning in the present description. The plurality of cells of each module may be arranged in the form of cell trays as described below. A modular battery can be composed of several modules connected together in series and / or in parallel depending on the intended application.

Throughout this presentation, unless expressly stated otherwise, a singular must be interpreted as a plural and vice versa.

The present invention relates to rechargeable modular electric batteries, that is to say comprising electrically rechargeable cells which are unitary electrochemical cells containing two electrodes immersed in an electrolyte. These cells are electrochemical energy accumulators, that is to say rechargeable electrochemical generators. Such a cell operates spontaneously in the generator direction when its electrodes are brought into contact by an external electrical circuit, by conversion of the chemical energy contained in the active substances that compose it directly into electrical energy via oxidation reactions. reduction (redox reactions), and these redox reactions being reversible, can accumulate electricity by connecting a power supply to its terminals creating a reverse current in the direction of discharge. The present invention provides a thermal regulation of a modular electric battery to efficiently dissipate and evacuate to the outside of the battery heat developed both by the cells and their connections.

Indeed, the thermal protection and control device according to the invention advantageously allows draining the heat conducted and dissipated at the ends of the cells, developed by the cells themselves and by the associated connectors. The thermal regulation of the battery according to the invention is thus optimal in that it is more efficient to recover the heat at the ends of the cells than at any other point, and it is also possible to recover the heat developed by Connectors, as explained below. The temperature of a cell can be calculated from an energy balance 30 involving: the internal heat flux (pg 'generated by the activity of the cell, associated with the reversible and irreversible losses for each electrochemical reaction) the flow (ha transferred to the ambient environment at temperature Ta.

The net thermal flux through an accumulator, 9, can be easily calculated as the balance between the internal and external flows, ie 9 = 9gen 9tra- The amount of heat stored in the battery, obtained by integration of the heat flow over time , 5 then makes it possible to calculate the temperature of the battery knowing the following relation (1): ## EQU1 ## where Cp is the capacitance The mean heat density of the cell and Mceli its mass The heat flux generated by the active part of the cells, noted as "gen", is written according to the following equation (2): ## EQU1 ## , the resistance of the cell [Q], OCV, open circuit voltage (the empty battery voltage) [V], I, the intensity of the current flowing in the cell [A], 15 T, the temperature of the cell [K], One distinguishes in equation (2): an ohmic contribution related to the losses by Joule effect ç'fo., - - RI 2, (aocv 20 entropy = a contribution so called entropic dU The value of the OCV and dT depends on the state of charge (SoC) which is itself calculated according to the intensity. The value of R depends on the state of charge and the temperature. / aocv (2) The heat dissipation of the cells is anisotropic considering the electrical and thermal characteristics of the battery cells. In general, the internal composition of the electrochemical cells induces significantly greater electrical and thermal cell conduction characteristics in the axial direction (defined by the main axis of symmetry supporting the connections) than in the radial direction (plane perpendicular to the direction axial defined above). As an example, the measurements made by Drake et al., 2014 on Li-ion cylindrical cells (SJ Drake et al, Measurement of anisotropic thermophysical properties of cylindrical Li-ion cells, Journal of Power Sources, 252 ( 2014) 298-304). As a result, the heat flux produced by the cells is substantially greater in the axial direction of the cells. Regardless of the heat dissipation associated with the active part of the cells, the metal connectors ensuring the electrical connection between the cells are also the seat of an irreversible heat dissipation by Joules effect, according to equation (3): 2 (3). ) connectivity - RI With: R, the resistance of the connection [Q], I, the intensity of the current circulating in the connection [A]. As a result, the heating of the batteries in nominal use corresponds to the sum of the effects given in equations (1) and (3). The modular electric battery according to the invention comprises: a set of cells electrically connected to each other, each cell comprising a positive terminal and a negative terminal, the cells being arranged next to one another to form at least one plate comprising at least one less a first face comprising means for electrical connection between cells, - a thermal protection and regulation device comprising at least one joint of material both electrical insulator and thermal conductor interposed between the electrical connection means of the first face and a thermal collector comprising at least one plate of thermally conductive material in contact with the seal, - a housing containing at least the set of cells and having at least one thermally conductive wall in contact with said plate.

According to the invention, the dissipation of heat and its evacuation outside the modular battery is only passive. Thus, it is possible to overcome the complex systems of thermal regulation, which can be cumbersome and energy consumers.

A first embodiment of the battery according to the invention is illustrated in Figure 1. The battery is shown schematically in a cross section. Only a part of the battery is represented. For the remainder of the description, a longitudinal direction X is defined according to the length of the battery, a transverse direction Y according to the width of the battery, the plane (XY) being defined as horizontal. A vertical direction Z is also defined according to the height of the battery, perpendicular to the plane (XY), forming with the direction Y a vertical plane (YZ). The modular battery 1000 comprises a module comprising a plurality of electrochemical cells for storing and restoring electrical energy 100. The cells 100 are prismatic Li-ion cells whose positive and negative terminals are situated on one and the same face of the cell. . The cells 100 are electrically combined in series and / or parallel, and are arranged to form one or two trays (101, 102). All of the cells thus connected develop a voltage and capacitance suitable for applications for which a single cell is not sufficient, such as vehicle traction applications. FIG. 1 shows an example of a battery comprising two cell trays 101 and 102. A tray is defined as an arrangement on the same horizontal plane (XY) of several cells arranged next to each other and electrically connected. The cells are arranged on each plate parallel to their main axis of symmetry, which passes through the face or faces of the cell carrying the terminals, in the vertical direction Z. Each plate is formed of one or more rows of cells 100, each row of cells extending in transverse direction Y.

In the cross-section of FIG. 1, six cells 100 aligned in the Y direction are shown for each of the trays 101 and 102 to form a row. The two plates 101 and 102 are arranged one above the other in the vertical direction Z. Each plate has an upper face opposite to a lower face, the upper face being turned towards the outside of the battery. The plate 101 thus has an upper face 101a and a lower face 101b, and the plate 102 has an upper face 102a and a lower face 102b, the two lower faces 101b and 102b are vis-à-vis within the module. The upper faces 101a and 102a, facing towards the outside of the module, comprise the terminals of the prismatic cells 100.

The cells 100 of each plate may be in contact, as shown in FIG. 1, or be separated from a space. A flange (not shown) is optionally used to maintain, in a tray, the cells 100 at a fixed distance from each other, as well as to maintain a spacing between the trays.

On a given plate, each cell 100 is connected via at least one of its terminals to one of the terminals of a neighboring cell 100 by means of a connection (110, 111) suitable for the passage of the current, through example a metal connector, such as a copper foil or nickel. Thus, all the cells, except in some cases those located on the periphery of the plate, are connected via their two terminals to two neighboring cells by a metal connector (110, 111). In FIG. 1, the cells aligned in a row for each plate are for example connected in series: the connectors (110, 111) shown connect a positive terminal to a negative terminal of two adjacent cells on the same row, the connectors connecting the other terminals of these same cells are located in another plane than that of the section of Figure 1. Each connector (110, 111) is surmounted by a seal (120, 121), preferably plane, electrical insulator and thermal conductor. Preferably, each seal covers most of the surface of the terminals connected by each connector. The seals are made of a non-conductive, electrically conductive polymeric material, including heat conductive fillers so as to preserve the electrical insulation while providing a certain level of thermal conduction. The thermal conductive fillers may be silicon carbide, ceramics, metals, graphite, for example in the form of powders. The joints, electrical insulators, preferably have resistivities greater than 106 Ohm / m. The thermal conductivity of the seals is preferably greater than 0.1 W / m / K. The seals can be in the form of slats (discontinuous form of the seal) or a continuous carpet.

The joints (120, 121) are placed between the connectors (110, 111) and a heat collector (130, 131), in the vertical direction Z. Each seal is thus inserted between the connectors (110, 111) of the first face (101a, 102a). ) trays and the thermal collector comprising at least one plate of thermally conductive material (130,230) in contact with the seal. These seals provide a thermal connection between the connectors (110, 111) and the thermal collector (130, 131) by substantial contact between their two faces. According to this first embodiment, the thermal collector comprises a plate having very good thermal conduction properties and which covers all the joints (120, 121) of a plate (101, 102). The module comprising two trays 101 and 102 is thus provided with two collecting plates 130 and 131 arranged outwardly as shown in FIG. 1. These plates make it possible to collect the heat from the connectors and the cells 100 of the entire module. Such a configuration also allows a homogeneous distribution of heat between the cells. The thermal collector is formed by one or more thermal conducting materials, preferably metallic materials, for example aluminum, or by composite materials containing thermal conductive fillers, such as silicon carbide, ceramics, metals, graphite, for example in the form of powders. The thermal collector has a thermal conductivity preferably greater than 10 W / m / K, and more preferably greater than 100 W / m / K.

The assembly formed by the cells 100, the connectors (110, 111), the seals (120, 121), and the collectors comprising the two plates 130 and 131, is included in a casing 140, so as to ensure a substantial contact between each of the plates. 130 and 131 and a thermally conductive wall (142, 141) of the housing 140. The term "housing" means the envelope delimiting the inside of the module from outside the module of the battery in contact with the air. Preferably, this housing is made of metal material, for example aluminum, so as to ensure a sealed partition between the inside of the housing and the outside while promoting thermal conduction. The casing may also be made of plastic or composite, comprising for example one or more thermoplastic polymers of PLA (polylactic acid), ABS (Acrylonitrile-butadiene-styrene), nylon type. The thermal conduction of the wall of the housing in contact with the plate is preferably greater than 0.1 W / m / K, and more preferably greater than 10 W / m / K. The housing, which can also be mounted in several parts of different types, is preferably sealed, and equipped with sealed passages for the input and output of the electrical connections of the module as required. The housing may comprise fins, on the outer face of the thermally conductive wall or walls of the housing outside the module, to improve the dissipation and evacuation of heat outside the battery, for example in contact with air. The thickness of the wall of the housing in contact with the collector plate is chosen, as a function of the material that composes it, so as to dissipate and evacuate the heat transmitted by the thermal collector, and to have a thermal conductivity such that it is preferentially defined above. By way of example, a thermally conductive wall of the adapted plastic housing preferably has a thickness of less than 5 mm.

The thermally conductive walls 142 and 141 of the housing 140 are respectively in contact with the plate 130 and the plate 131 of the thermal collectors, so as to develop a contact surface between each plate and each thermally conductive wall of the housing such that the heat of the all cells 100 is dissipated and discharged to the outside of the battery passively.

Thus, the modular battery according to the invention is advantageously designed to form a heat sink between the sources of heat production (cells and connectors) and the outside, which allows to effectively evacuate, by conduction through different materials put in contact, the calories produced in charge and discharge, or produced during a short circuit at the connectors. This limits the development of hot spots conducive to the thermal runaway of the battery. It also limits the development of thermal gradients in cells conducive to aging thereof. In addition, the mechanical protection of connectors provided by the housing and by the joints reduces the risk of occurrence and propagation of short circuit.

Although the cells are shown contiguous, in contact with each other, they could be spaced according to a variant of this first embodiment, for example by means of a flange, as mentioned above.

The description of this first embodiment has been made in relation to prismatic cells, having their two terminals on one and the same face. However, a variant with cells of another shape, also having their two terminals on the same face, or a variant comprising cells having a terminal at each end, as is conventionally the case of cylindrical batteries, for example of Li-ion type, may be envisaged according to the present invention. An advantage associated with a battery according to the invention comprising cells with their two terminals on one and the same face, such as prismatic cells, is that all the connectors connecting the cells to one another on the same plate are in contact with the heat seal, which makes it possible to avoid evacuating the heat of a connector that is not in contact with the thermal seal through the accumulator, and to avoid possible hot spots at the connectors that are not in contact with the seal. Various configurations of electrical connection, in series and / or in parallel, between the cells of the same plate are possible according to the invention, without modifying the general arrangement in sandwich of the joint surmounting the connectors, itself surmounted by the plate of the thermal collector which is in substantial contact and covered by a thermally conductive wall of the housing.

A second embodiment of the battery according to the invention is now described below in relation with FIGS. 2, 3 and 4. In this second embodiment, the battery comprises at least two cell trays, and the device protection and thermal regulation is similar to that of the first embodiment, except that a thermal bridge is provided by at least one rod of thermally conductive material connecting the plates of the collectors, and that preferably only one plate of collector associated with one of the two trays is in contact with a thermally conductive wall of the housing. Figure 2 is a schematic cross-sectional view illustrating a first example of battery according to this second embodiment. Only a portion of the battery is shown. The modular battery 2000 comprises a module comprising a plurality of electrochemical cells for storing and restoring electrical energy 200. The cells 200 are cylindrical Li-ion cells whose positive and negative terminals are located at both ends. The cells 200 are combined electrically in series and / or parallel, and are arranged so as to form two plates 201 and 202. The set of cells thus connected develop a voltage and a capacity adapted to applications for which a single cell is not sufficient. not, such as vehicle traction applications.

Each tray is defined and formed as described in connection with FIG. 1. On the cross-section of FIG. 2, four cells 200 aligned in the Y direction are shown for each of the trays 201 and 202 to form a row. The two plates 201 and 202 are arranged one above the other in the vertical direction Z. Each plate has an upper face opposite to a lower face, the upper face being turned towards the outside of the battery. The plate 201 thus has an upper face 201a and a lower face 201b, and the plate 202 has an upper face 202a and a lower face 202b, the two lower faces 201b and 202b being vis-à-vis within the module. The upper faces 201a and 202a are turned towards the outside of the module, and comprise a set of connectors 15 connecting the terminals of the cylindrical cells 200. According to this embodiment, the cells 200 are spaced apart from each other. The space between the cells of the same row can be used to allow passage to rods 250 connecting two collecting plates 230 and 231 described below. Alternatively, the cells may be in contact. A flange (not shown) is preferably used to maintain, within a tray, the cells 200 at a fixed distance from each other, as well as to maintain spacing between the trays. On a given plate, each cell 200 is connected via at least one of its terminals to one of the terminals of a neighboring cell 200 by means of a connection (210, 211, 1113) suitable for the passage of current through for example a metal connector, such as a foil of copper or nickel. The connectors 210 and 211 are located on the upper faces 201a and 202a of the plates 201 and 202 and connect two by two neighboring cells of the same row. The connectors 213, located on the lower faces 201b and 202b of the plates 201 and 202, also connect the cells of the same plate between them. Connectors 212 also allow 30 to connect the cells of the two trays. An example of an electrical connection between the cells is given in FIG. 2. The cells aligned in a row for each plate are, for example, connected electrically in pairs in series along the Y direction, by the connectors 210, 211 and 213, and the The cells between the two plates 201 and 202 are for example electrically connected in series in the Z direction by connectors 212. Each connector (210, 211) located on the upper faces 201a and 202a of the plates 201 and 202 is surmounted by a joint (220,221), preferably plane, electrical insulator and thermal conductor. Preferably, each seal covers most of the surface of the terminals connected by each connector. The seals are made of a non-conductive, electrically conductive polymeric material, including heat conductive fillers so as to preserve the electrical insulation while providing a certain level of thermal conduction. The thermal conductive fillers may be silicon carbide, ceramics, metals, graphite, for example in the form of powders. The joints, electrical insulators, preferably have resistivities greater than 106 Ohm / m. The thermal conductivity of the seals is preferably greater than 0.1 W / m / K. The seals can be in the form of slats (discontinuous form of the seal) or a continuous mat. The seals (220, 221) are placed between the connectors (210, 211) and a collection plate (230, 231) of a thermal collector, in the direction Z. Each seal is thus interposed between the connectors (210, 211) of the first face (201a, 202a) of the trays and the thermal collector comprising at least one plate of thermally conductive material (230,231) in contact with the seal. These seals provide a thermal connection between the connectors (110, 111) and the thermal collector (130, 131) by substantial contact between their two faces. These seals provide a thermal connection between the connectors (210, 211) and the thermal collector (230, 231) by substantial contact between their two faces. According to this example of the second embodiment, the two thermal collectors comprise two plates 230 and 231 having very good thermal conduction properties. Each plate covers all the joints of a plate positioned on the connectors presented by the upper faces 201a and 202a of the plates 201 and 202. The module comprising two plates 201 and 202 is therefore provided with two plates 230 and 231 disposed towards the outside as illustrated in Figure 2. The two plates 230 and 231 are interconnected by rods 250 also have very good thermal conduction properties. These rods are fixed at their ends to the plates 230 and 231 by any appropriate fastening means, for example by screwing or welding, so as to provide an effective thermal bridge. The rods 250 are of cylindrical shape. However, the stems may have other forms, preferably compatible with the shape of the cells in particular to facilitate their insertion between them. Thus, if prismatic cells are used in this second embodiment, a parallelepipedal shape of the rods may be appropriate, and the rods may be thin plates elongate in the vertical direction Z. The set of rods and collectors also forms a rigid structure enveloping the cells in the housing, which protects the battery from deformations induced by external forces exerting on the housing. The thermal collectors, comprising the two plates 230 and 231, as well as the rods 250, consist of one or more thermal conducting materials, preferably metallic materials, for example aluminum, or composite materials containing thermal conductive fillers, such as silicon carbide, ceramics, metals, graphite, for example in the form of powders. The heat collectors and the rods have a thermal conductivity preferably greater than 10 W / m / K, and more preferably greater than 100 W / m / K. The set of plates and rods makes it possible to collect the heat of the connectors and the cells 200 of the whole module. Such a configuration also allows a homogeneous distribution of heat between the cells, including between the cells of the different trays.

The assembly formed by the cells 200, connectors (210,211), seals (220,221), and the thermal collector is included in a housing 240 so as to ensure a substantial contact between at least one collector plate and a thermally conductive wall. of the housing 240, in this case the collection plate 230 and the thermally conductive wall 242 of the housing according to FIG.

The housing is identical to that described in connection with Figure 1, except that only one thermally conductive wall is required to dissipate and discharge heat to the outside. Preferably, this housing is made of metal material, for example aluminum, so as to ensure a sealed partition between the inside of the housing and the outside while promoting thermal conduction. The housing may also be made of plastic or composite, comprising for example one or more thermoplastic polymers of the PLA (polylactic acid), ABS (Acrylonitrilebutadiene-styrene), nylon type. The thermal conduction of the wall of the housing in contact with the plate is preferably greater than 0.1 W / m / K, and more preferably greater than 10 W / m / K. The housing, which can also be mounted in several parts of different types, is preferably sealed, and equipped with sealed passages for the input and output of the electrical connections of the module as required. The thermally conductive wall 242 of the housing 240 is in contact with the thermally conductive plate 230 of the thermal collector, so as to develop a contact surface such that the heat of all the cells 200 is dissipated and discharged to the outside of the battery passively. The rods 250 may be attached to the housing 240. Figure 3 is a schematic longitudinal sectional view (in a plane parallel to the XY plane) of the battery shown in Figure 2. Only a portion of the battery is shown. This section makes it possible to better understand an example of the configuration of the cells of a tray, the connectors and the arrangement of the rods. On this section are not shown the seals, the heat sink and the housing. On the section of Figure 3 is visible the lower plate 201, in particular the upper face 201a, having six rows r1 to r6 of cells 200, each row having 4 cells. The connectors 210 electrically connect the cells 200, for example two by two on the same row, and all the cells in the X direction of two adjacent rows. The connectors 210 are metal foils with holes to allow the passage of the rods 250, with which any contact is avoided. The rods 250 are disposed between four adjacent cells of the tray. The space between four adjacent cylindrical cells may indeed be larger than the space between two adjacent cells on the same row or in the Y direction, and allow easier insertion of the stems. Fifteen rods 250 are thus arranged in the module comprising m = 6 rows of n = 4 cells per row, ie (n-1) x (m-1) rods with n the number of cells per row and m the number of rows, constituting an example of arrangement of the rods. Other arrangements of the rods are possible, with preferably at least one rod, and more preferably a rod number between 2 and (n-1) x (m-1). The stems can thus be distributed randomly or in a particular symmetry between the cells of the trays. One or more rods may also be positioned at the periphery of the trays, between the walls of the housing and the perimeter formed by the cells. Thermal conduction between the collection plates is improved with increasing number of rods.

According to the second embodiment, the battery may comprise more than two trays of cells. In this case, for each additional plate, arranged between the two plates, an additional collection plate having very good thermal conduction properties, and pierced with holes for passing the rods, is inserted in contact with an additional seal placed on one of the faces of the additional plate intermediate to the two trays. The contact between the additional collection plates and the stems is ensured in the rules of the trade, by adjustment and welding or by using a thermal paste. By way of example, FIG. 4 schematically represents a variant with three trays of the second embodiment.

The description of the identical elements between the first and second variants of the second embodiment, bearing the same references in FIGS. 2, 3 and 4 are not repeated here. According to this variant, the battery 3000 comprises a third plate 302, which is an intermediate plate disposed between the first plate 201 and the second plate 202, along the Z axis, which is also the axis of symmetry of the cells 200. and the second plate have their upper face 201a and 202a closer to the housing 240 than their lower face 201b and 202b. This intermediate plate 302 is organized in the same way as the plates 201 and 202 from the point of view of the arrangement of the cells 200 and connectors 311 and 313 which connect the terminals of the cells of the tray, the connectors 311 being carried by a first face 302a of the intermediate plate 302 and the connectors being carried by a second face 302b of the intermediate plate. Other connectors 312 and 314 make it possible to electrically connect the cells of the intermediate plate and those of the first plate 201 and the second plate 202.

According to this variant, the third plate comprises a protection and thermal regulation device similar to the other two plates. The battery therefore comprises, for the third plate 302, an additional seal 322, preferably plane, of electrical insulating material and thermal conductor surmounting each connector of the first face or the second face of the third plate, for example the first face 302a such The additional seal 322 preferably covers most of the terminals connected by each connector. The additional seal 322 has holes allowing the passage of the rods 250. An additional collection plate 332 of thermally conductive material, like the other collection plates 230 and 231, is disposed on said additional seal, and also comprises holes for the passage of the stems. The contact between the additional plate 332 and the rods 250 is for example made by adjustment and welding, or by use of a thermal paste, for example a grease comprising silver particles, or a thermal conductive silicone. The cells have been described in this second embodiment, with reference to FIGS. 2 and 3, as having a cylindrical shape, but any other form, such as prismatic cells, of parallelepipedal shape, can be envisaged. According to this second embodiment, it is advantageously possible to evacuate the heat towards the outside via a single face of the housing, thus allowing more flexibility, and therefore simplicity, for the arrangement of components. in the battery and for its integration into the system that contains it. In the case of integration into a vehicle for example, the battery can be introduced under the sill, and thus be cooled at the level of said face of the housing by forced convection with the outside air, the speed of the air depending on the speed of the vehicle. The use of sensors to instrument the inside of the module, the addition of dissipative elements or circuits inside or outside the module, or the insertion of electronic components inside the module of the module. battery according to the invention can be envisaged, without departing from the scope of the present invention. The present invention is not limited to the various embodiments and variants thereof described above and illustrated by the figures, which can be modified without departing from the objects of the invention, and which can be combined with one another. . The modular battery according to the invention can be used for many applications. Advantageously, the modular battery according to the invention can be integrated in an electric or hybrid vehicle, and used for traction of such a vehicle, providing more safety during the operation of the vehicle through optimized thermal regulation and effective mechanical protection of the battery limiting the occurrence and propagation of short circuit in the battery.

Examples The following examples make it possible to illustrate the thermal regulation of an example of a battery according to the invention based on a numerical simulation, and to compare the heat developed in a battery according to the invention and in batteries without a device. protection and thermal regulation according to the invention. MODULAR BATTERY OF THE INVENTION A Li-ion battery module consisting of two superposed plateaus of 26650-size LFP / C cylindrical cells of capacitance 3Ah connected in series / parallel by metallic connectors (busbar nickel of a thickness of 200 lm). The maximum cell temperature specified by the manufacturer is 56 ° C. Each plate comprises at least one alignment of 8 cells constituting a row. The distance between the cells of the same row within a plate is set at 2 mm. The distance between the rows within a tray is set at 2 mm. The distance between the trays is 9 mm. The whole is held by flanges. The module comprises 4 mm thick individual electrical and thermally conductive insulating plastic joints and two metal collector plates forming two thermal collectors, 6 mm thick. The individual seals provide the connection between the connectors of the cells and the metal plates of the thermal collectors. The latter are in direct contact with the upper and lower faces of the waterproof plastic case 2 MM thick. Modular batteries according to the prior art A first reference battery according to the state of the art comprises a module comprising a simple waterproof plastic case of thickness 2 mm.

A second reference battery according to the state of the art also comprises a module comprising a simple waterproof plastic case 2 mm thick. The housing further comprises a bottom provided with aluminum fins. In both cases, the module comprises two superimposed trays of 26650-size LFP / C cylindrical Li-ion cells with 3Ah capacity connected in series / parallel by metal connectors (200 nm thick nickel bar bus). The maximum cell temperature specified by the manufacturer is 56 ° C. Each plate comprises at least one alignment of 8 cells constituting a row. The module is clamped between two flanges, and a distance of 2 cm is left on each side edge of the housing. In the upper part, a space of about 1 cm is provided, in particular to position the electronic cards. These conditions are applied for the three batteries tested by simulation. The entire module has an initial temperature of 20 ° C. The indoor air is ventilated by natural convection between the cells and the trays of the module. The heat exchange coefficient is set at 5 W / m2 / K. The external ventilation is performed on the 6 faces of the housing by forced convection of air, with a heat exchange coefficient of 100 W / m2 / K. This module is electrically solicited according to a charging and discharging cycle, namely a recharge of SA for 10 minutes followed by an SA discharge for 10 minutes. The module undergoes 6 times this type of cycling corresponding to a duration of 2 hours in total. The thermal conductivity values at 20 ° C of the materials and components considered are summarized in the table below. air component Aluminum Seal Neither plastic paraffin Axial cell Thermal radial cell Lambda W / mK 0.026 237 2 50 0.2 0.2 14 1.4 Figure 5 shows the result of the rise in temperature observed after the cycling predefined in the first reference battery according to the prior art.

FIG. 6 shows the result of the rise in temperature observed after the predefined cycling in the second reference battery according to the prior art. A scale of temperature is given on the right by a variation of gray levels. In the figures, the abscissa represents a distance in meters in the direction Y 5 and the ordinate represents a distance in meters in the direction Z (height of the battery). It is found that the temperature of the cells increases to about 70 ° C, with or without fins, as indicated by the dashed lines on the temperature scale. This temperature rise is greater than the maximum temperature specified for the Li-ion cells of these examples. Thus, batteries according to the prior art as described can not ensure the two hours of use provided safely. FIG. 7 shows the result of the rise in temperature observed after the predefined cycling in the example of modular battery according to the invention. The temperature of the cells after cycling remains homogeneous around 36 ° C, as indicated by the dashed lines on the temperature scale, 34 ° C difference with reference cases according to the prior art. Thus, the battery according to the invention as exemplified, allows to continue the use of the module for more than 2 hours. 20

Claims (16)

REVENDICATIONS1. Modular electric battery (1000, 2000, 3000) comprising: - a set of electrochemical cells for storing and restoring electrical energy (100, 200) electrically connected to each other, each cell comprising a positive terminal and a negative terminal, the cells being arranged next to each other to form at least one plate (101, 201) comprising at least a first face (101a, 201a) having electrical connection means (110, 210) between the cells, - a protective device and thermal regulation comprising at least one joint of material both electrical insulator and thermal conductor (120,220) interposed between said electrical connection means (110, 210) of said first face and a thermal collector comprising at least one plate of thermally material conductor (130,230) in contact with said seal, - a housing (140,240) containing at least said set of cells and comprising at least a thermally conductive wall (142, 242) in contact with said plate. 2) battery according to claim 1, comprising at least two trays of cells (101, 102, 201, 201), arranged facing each other by a second face (101b, 102b, 201b, 202b), opposite said first face comprising means of connection. 3) battery according to claim 2, comprising at least one rod of thermally conductive material (250) fixed at both ends to said plates (230,231) of each of the two trays (201,202), said rod being inserted between the cells (200). 25 4) Battery according to claim 3, wherein the housing (240) comprises a single thermally conductive wall (242) in contact with a single plate (230) of the collector, so as to develop a contact surface such that the heat of the all of the cells are dissipated and discharged to the outside of the battery passively. 5) battery according to one of claims 3 to 4, comprising at least one intermediate plate (302) disposed between said two plates (201,202), and having a protective device and thermal regulation similar to the other trays, said at least one rod thermally conductive material being further secured to the plate of the intermediate plate (302). 6) battery according to one of claims 3 to 5, comprising a plurality of rods distributed between the cells, each rod being preferably arranged between four adjacent cells located in two rows of cells of the same plate, the set of rods. preferably comprising between 2 and (n-1) x (m-1) stems, where n is the number of cells per row of a tray and m is the number of rows of the same tray. 7) Battery according to one of the preceding claims, wherein the cells are cylindrical in shape, preferably each having their positive terminal and their negative terminal on two opposite faces of the cell. 8) Battery according to one of claims 1 to 6, wherein the electrochemical cells are prismatic cells, each having their positive terminal and their negative terminal on the same face of the cell. 9) battery according to one of the preceding claims, wherein the cells are of the Li-ion type. 20 10) battery according to one of the preceding claims, wherein said plate is formed of one or more thermally conductive material, preferably metal and / or composite material comprising thermally conductive charges. 25 11) Battery according to one of the preceding claims, wherein said seal is in a discontinuous form and consists of a set of lamellae. 12) Battery according to one of claims 1 to 10, wherein said seal is in the form of a continuous belt. 30 13) Battery according to one of the preceding claims, wherein said seal is plastic. 14) A battery according to one of the preceding claims, wherein the thermally conductive wall of the housing is of plastic or composite material preferably comprising one or more thermoplastic polymers of polylactic acid, acrylonitrile-butadiene-styrene, or nylon type. 15) Battery according to one of claims 1 to 13, wherein the thermally conductive wall of the housing is metal, preferably aluminum. 16) Electric or hybrid vehicle comprising a battery according to one of the preceding claims. 10