FR3072503A1 - ELECTRIC ENERGY STORAGE MODULE WITH INTEGRATED LEAK RESISTANCE - Google Patents

Abstract

The invention relates to a module (5) for storing electrical energy, containing, housed in an envelope (6), an assembly of at least one row of elements ( E) of electrical energy storage such as electrochemical cells or supercapacitors, the slats of which are electrically coupled by means of electrical connection parts called control rods. link (7) said elements being held in place in said envelope characterized in that at least a part of the envelope (6) or at least a part of a wedging piece ( 8), interposed between the module casing and a longitudinal edge of one of the rows of storage elements, comprises an electrically conductive zone in contact between two poles of an element. storage element (s) and / or between at least one pole of a first pair of storage elements (E) and a pole of a second pair of elements (E ) of stock age, and constituting a mastered leakage resistor integrated with said module, creating a current flow.

Description

FIELD OF THE INVENTION

The present invention relates to the general technical field of electrical energy storage systems. More particularly, the invention relates to electrical energy storage modules incorporating an assembly of electrical energy storage elements of the super capacitor or battery type. The present invention relates more precisely to the balancing of the various energy storage elements arranged in such a storage module.

PRIOR ART

Electrical energy storage systems generally comprise a plurality of elements, also called cells, for energy storage, such as super capacitors or super capacitors, or even batteries, these elements being assembled in series to form electrical energy storage modules or packs. In these modules, the adjacent electrical energy storage elements are electrically coupled by means of electrical connection pieces called connecting bars.

To ensure that these electrical energy storage elements all operate at the same voltages, in order to optimize their lifetimes, a balancing device is often added in parallel with each of these storage elements.

This balancing device is generally based on a current drift, continuous or dependent on a voltage threshold, which is implemented electrically by the addition of a leakage resistance in parallel with the storage element, resistance well below the natural resistance between the two electrodes of the electric energy storage element. This balancing device creating a calibrated leakage resistance is positioned outside of said energy storage element via wiring, the ends of which are connected to the positive (+) and negative (-) poles of said element.

Such an addition of electrical connections to this external balancing device therefore requires electrical and mechanical connections with the poles of the element (terminals or parts of the envelope), such as flexible or rigid cables or electrical conductors and often even via flexible or rigid electronic cards supporting balancing components.

The main problem with the balancing devices of the prior art lies in the need to add such external parts, which must be protected from the environment of the cell or energy storage element: these protections are protections mechanical but also chemical or climatic, during the manufacturing phases and especially during the life phases beyond manufacturing. This therefore often requires the creation of zones or compartments dedicated to the balancing device in the modules grouping one or more assemblies of energy storage elements, compartments in which the balancing components are protected.

Another problem also resides in the frequent presence of long links between the elements and the balancing components which are grouped in certain areas of the module to facilitate protection, manufacture and installation. These long links, often different in length from one storage element to another, can induce differences in electrical resistance due to the wiring and therefore ultimately differences in balancing quality for the storage elements.

Finally, the addition of numerous external parts to ensure the electrical connections to the balancing components (cables, connections with the element, connectors, tracks of electronic cards, etc.) only reduces the reliability of the balancing system. by the increase in possible sources of circuit failure, all the more if the system is subjected to mechanical aggressions of the vibration or shock type in on-board applications, which stress the connections by degrading them by fatigue.

GOALS AND SUMMARY

A first object of the invention is therefore to remedy the problems described above encountered in the electrical energy storage systems of the prior art, by proposing a solution which reduces, or even eliminates, the number of parts external to the electrical energy storage elements.

Another object of the invention is to propose an electrical energy storage module, grouping together a plurality of energy storage elements, comprising a balancing system integrated into said module and allowing space saving in said modules. compared to those of the prior art.

A first object of the invention therefore relates to an electrical energy storage module, containing, housed in an envelope, an assembly of at least one row of electrical energy storage elements such as electrochemical cells or super capacitors, the poles of which are electrically coupled by means of electrical connection pieces called link strips, said link having an electrical resistance Rb, said elements being held in place in said envelope. This storage module is characterized in that at least part of the casing or at least part of a wedging piece, interposed between the casing of the module and a longitudinal edge of one of the rows of elements of storage, comprises an electrically conductive zone, in contact between two poles of a storage element and / or between at least one pole of a first pair of storage elements and a pole of a second pair of storage elements , and constituting a controlled leakage resistance integrated into said module, creating a current drift.

Thus, it is a part of the constituents of said energy storage module which forms the integrated leakage resistance, without requiring any wiring or any specific added connection. This not only saves space within the module, but also greatly facilitates manufacturing and assembly of the elements.

Advantageously, the electrical contact constituting the leakage resistance has a resistance Rf, with Rf »Rb, the value of Rf being at least equal to 100 times the value of Rb.

According to a first embodiment of the invention, two wedging pieces are, partially or entirely in contact with at least one sector of the electrically conductive casing connecting the two wedging pieces, creating the leakage current through said pieces wedging and said sector (or wall) of said envelope.

In this first embodiment, balancing is thus ensured between all of the elements in contact with the setting piece or pieces. Indeed, thus, the wedging piece or pieces, which usually also provide electrical insulation between the row of electrical energy storage elements and the casing of the module, is (are) configured (s) to present, according to the invention, degraded electrical insulation so as to slightly increase its (their) conductivity and directly create a controlled leakage resistance in its (their) breast.

According to a second embodiment of the invention, said electrically conductive area is a portion of a wedging piece.

According to a third embodiment of the invention, said electrically conductive area is a part added to the wedging piece.

By “part added to the wedging piece it may be a part made of a basic material of the same kind (for example the same basic polymer matrix) but whose electrical insulating character has been degraded, to give it a electrical conductivity of a specific value.

Advantageously, said wedge piece or said portion of the wedge piece or part added to the wedge piece is made of a composite material with an adhesive or elastomeric polymer matrix in which particles of at least one electrically conductive material are dispersed. The electrically conductive material of the composite material is preferably chosen from carbon charges, metallic particles and one of their mixture.

Said carbonaceous fillers can be chosen from carbon black, graphite, carbon fibers and nanofibers, carbon nanotubes and graphene. The metallic particles can be chosen from particles of aluminum, silver, copper, platinum, iron, cobalt and / or nickel.

According to a fifth embodiment of the invention, the envelope of the module is made of metallic material, or of polymeric material coated with an inner coating of electrically conductive material, and at least part of the inner wall of the envelope is in direct electrical contact with at least two poles, of opposite polarity, of a row of electrical energy storage elements.

According to a sixth embodiment of the invention, the wedging piece or pieces are formed by protuberances formed on the inner face of the envelope of the energy storage module.

BRIEF DESCRIPTION OF THE DRAWINGS

The description of the invention is supplemented below by the description of exemplary embodiments given by way of illustration and not limitation, with reference to the appended drawings, in which:

- Figure 1 shows schematically an energy storage module incorporating a row of storage elements according to an embodiment of the invention in which the wedging pieces and the envelope of the module form the integrated leakage resistance;

- Figure 2 shows schematically an energy storage module according to another embodiment of the invention in which the integrated leakage resistance is carried out directly via the envelope of the module;

- Figure 3 shows schematically an energy storage module according to yet another embodiment of the invention in which each of the wedging pieces forms an integrated leakage resistance;

- Figure 4 shows schematically an energy storage module according to yet another embodiment of the invention in which a portion of the wedging pieces forms the integrated leakage resistance;

- Figure 5 shows schematically an energy storage module according to yet another embodiment of the invention in which the integrated leakage resistance is a part added to the wedging piece between the storage elements.

DETAILED DESCRIPTION

Referring to the figures, an example of an electrical energy storage module 5 has been shown schematically incorporating a row of four electrical energy storage elements E which may be electrochemical cells or super capacitors. These elements E, spaced from each other are electrically coupled and connected in series by bars 7 connecting between the positive pole of an element and the negative pole of the adjacent element.

All the electrical energy storage elements E are housed in an envelope 6 closing said module 5 and held in place in said envelope 6 by wedging pieces 8, generally made of elastomeric material. In the example shown schematically in FIG. 1, these wedging pieces 8 are in the form of a pair, each wedging piece 8 coating the poles and connecting bars 7 with an edge or longitudinal side of the row of elements. E for electrical energy storage.

In the prior art, these wedging pieces also provided electrical insulation, the current flowing only through the connecting bars. According to one embodiment of the invention, the two wedging pieces 8 have degraded electrical insulation (shown diagrammatically by the hatched areas in FIG. 1), allowing the creation of a leakage current through said pieces, the envelope 6, or at least the internal face or internal wall, of said envelope, also being electrically conductive, the external face or external wall of said envelope of module 5 being, for its part, insulating.

As a variant, it can be provided that only one sector of the envelope comprised between the two wedging pieces 8 can be conductive. Thus the integrated leakage resistance is constituted by the wedging pieces 8 and the sectors of the envelope

6.

The conductivity of the elastomer of the wedging pieces 8 is obtained, for example, by adding, during its formulation, conductive particles of metallic type (for example aluminum powder) or carbonaceous fillers (for example graphite powder), the rate of which, within the elastomer matrix, allows the conductivity of said setting piece to be controlled. It is thus possible to control the leakage current of the various storage elements with the poles of which the wedging pieces are in contact.

According to another embodiment shown diagrammatically in FIG. 2, it is the envelope 6, or at least its internal face or internal wall, (partially conductive or its internal coating) which is in direct contact with at least one negative pole d 'an element E of electrical energy storage (for example here element 1) and at least one positive pole of another element E (for example here element 4 at the end of the row) of the row of elements E. As a variant (not shown), only one sector of the casing 6 comprised between the contact zones of the element 1 and of the element 4 can be conductive. According to another variant (not shown) the wedging piece or pieces 8 are formed by protuberances formed on the inner face of the casing 6 of the energy storage module 5.

According to another embodiment shown diagrammatically in FIG. 3, each of the wedging pieces 8 forms an integrated leakage resistance, each on one side of the row of electrical energy storage elements E.

According to other embodiments shown diagrammatically in FIGS. 4 and 5, the setting is carried out such that certain zones with controlled conductivity (hatched) are located only at the places strictly necessary in the electrical sense, that is to say directly between the negative pole of element 1 and the positive pole of element 2, between the negative pole of element 2 and the positive pole of element 3. The leakage resistance is thus established between pairs d 'elements E.

These zones with controlled conductivity can be portions 9 of the wedging pieces 8, as shown diagrammatically in FIG. 4 or added parts, as visible in FIG. 5.

In this case, the possible remainder of the wedging pieces 8 (points areas 10, according to the example of FIG. 4) outside the necessarily conductive areas is ideally insulating or with conductivity much lower than that of the controlled conductivity areas, in order not to disturb the resistance values of the zones provided for this purpose by adding parallel resistances which would be uncontrolled.

Claims (11)

1. Electric energy storage module, containing, housed in an envelope (6), an assembly of at least one row of electric energy storage elements (E) such as electrochemical cells or super capacitors, the poles of which are electrically coupled by means of electrical connecting pieces called connecting bars (7), said link having an electrical resistance Rb, said elements being held in place in said envelope, characterized in that at least part of the casing (6) or at least part of a wedging piece (8), inserted between the casing (6) of the module and a longitudinal edge of one of the rows of storage elements, comprises an electrically conductive zone in contact between two poles of a storage element (E) and / or between at least one pole of a first pair of storage elements (E) and a pole of a second pair of storage elements (E) storage , and constituting a controlled leakage resistance integrated into said module, creating a current drift. 2. Electric energy storage module according to claim 1, characterized in that the electrical contact constituting the leakage resistance has a resistance Rf, with Rf "Rb, the value of Rf being at least equal to 100 times the value of Rb. 3. Electric energy storage module according to one of claims 1 or 2, characterized in that two wedging pieces (8) are, partially or entirely in contact with at least one sector of the envelope (6) electrically conductor connecting the two wedging pieces (8), creating the leakage current through said wedging pieces (8) and said sector of said casing (6). 4. Storage module according to one of claims 1 or 2 characterized in that said electrically conductive area is a portion (9) of a wedging piece (8). 5. Storage module according to one of claims 1 or 2 characterized in that said electrically conductive area is an added part (11) to said wedging piece (8). 6. Electric energy storage module according to any one of claims 3 to 5, characterized in that said wedging piece (8) or said portion (9) of the wedging piece or added part (11) to the wedging piece (8) is made of a composite material with an adhesive or elastomeric polymer matrix in which particles of at least one electrically conductive material are dispersed. 7. Electric energy storage module according to claim 6, characterized in that the electrically conductive material of the composite material is chosen from carbon charges, metallic particles and one of their mixture. 8. Electric energy storage module according to claim 7, characterized in that the carbon charges are chosen from carbon black, graphite, carbon fibers and nanofibers, carbon nanotubes and graphene. 9. Electric energy storage module according to claim 7, characterized in that the metallic particles are chosen from aluminum, silver, copper, platinum, iron, cobalt and / or nickel particles. . 10. Storage module according to one of claims 1 or 2 characterized in that the casing (6) of the module (5) is made of metallic material, or of polymer material coated with an inner coating of electrically conductive material, and at least part of the inner wall of the envelope (6) is in direct electrical contact with at least two poles, of opposite polarity, of a row of elements (E) for storing electrical energy. 11. Storage module according to any one of the preceding claims, characterized in that the wedging piece or pieces (8) are formed by protuberances formed on the inner face of the casing (6) of the storage module (5). energy. 1/3