阅读说明：本技术 具有带引流插入件的棱柱形电化学电池的存储装置以及相关联的蓄电池 (Storage device having prismatic electrochemical cells with drainage insert and associated accumulator ) 是由 M·西莫内蒂 M·纳苏姆比 于 2020-03-10 设计创作，主要内容包括：本发明公开了一种电能存储装置(DS),所述电能存储装置包括：至少一个电化学电池(CE),所述电化学电池是棱柱形的并且包括锂离子活性部分(PA),所述锂离子活性部分容置在保护罩(EP)中,所述保护罩包括由具有第一热导率的材料制成的第一壁(P1),所述第一壁与第二壁连成一体；以及热交换器,所述第二壁抵靠着所述热交换器安置,并且所述热交换器负责排泄由所述电化学电池(CE)产生且经转移到所述保护罩(EP)中的热量。所述第一壁(P1)的至少其中一个包括插入件(ID),所述插入件延伸直到所述第二壁并且具有大于所述第一热导率的第二热导率,并且所述插入件负责朝向所述第二壁引流经转移到所述第一壁(P1)中的热量。(The invention discloses an electrical energy storage Device (DS), comprising: at least one electrochemical Cell (CE) prismatic and comprising a lithium-ion active Portion (PA) housed in a protective casing (EP) comprising a first wall (P1) made of a material having a first thermal conductivity, said first wall being integral with a second wall; and a heat exchanger against which the second wall is disposed and which is responsible for draining the heat generated by the electrochemical Cell (CE) and transferred into the protective cover (EP). At least one of the first walls (P1) comprises an Insert (ID) extending up to the second wall and having a second thermal conductivity greater than the first thermal conductivity, and the insert is responsible for directing towards the second wall the heat transferred into the first wall (P1).)

1. An electrical energy storage Device (DS) comprising: i) at least one electrochemical Cell (CE) for storing electric energy, said electrochemical cell being prismatic and comprising a lithium-ion active Portion (PA) housed in a protective casing (EP) comprising a first wall (P1) made of a material having a first thermal conductivity, said first wall being integral with a second wall (P2); and ii) a heat Exchanger (EC) against which the second wall (P2) is seated and which is responsible for draining the heat generated by the electrochemical Cell (CE) and transferred into the protective casing (EP), characterized in that at least one of the first walls (P1) comprises an Insert (ID) which extends up to the second wall (P2) and has a second thermal conductivity greater than the first thermal conductivity, and which is responsible for conducting towards the second wall (P2) the heat transferred into the first wall (P1).

2. Electrical energy storage device according to claim 1, characterized in that each Insert (ID) is housed in a housing defined in the material of the first wall (P1).

3. Electrical energy storage device according to claim 2, characterized in that each Insert (ID) has a section in a plane parallel to the second wall (P2) in the form of a face having a greater width in the vicinity of a first face (F1) of the first wall (P1) oriented towards the lithium-ion active Portion (PA) of the electrochemical Cell (CE) than in the vicinity of a second face (F2) of the first wall (P1) opposite to the first face (F1), in order to tolerate the volume expansion during the charging or discharging of the electrochemical Cell (CE).

4. Electrical energy storage device according to claim 1, characterized in that each Insert (ID) is fixedly integral with a first face (F1) of the first wall (P1) oriented towards a lithium ion active Portion (PA) of the electrochemical Cell (CE).

5. Electrical energy storage device according to any of claims 2 to 4, characterized in that each Insert (ID) is made of graphite.

6. Electrical energy storage device according to claim 1, characterized in that each Insert (ID) is made of a phase change material and is housed in a hermetic housing defined in the material of the first wall (P1).

7. The electrical energy storage device according to any one of claims 1 to 6, characterized in that each electrochemical Cell (CE) comprises an electrically insulating cover (EI1) interposed between the lithium-ion active Portion (PA) and the protective cover (EP).

8. The electrical energy storage device according to any one of claims 1 to 7, characterized in that the electrical energy storage device comprises at least two electrochemical Cells (CE) coupled in series and/or in parallel, each of the at least two electrochemical cells comprising a second wall (P2) disposed against the heat Exchanger (EC).

9. Rechargeable accumulator according to the previous claims, characterised in that it comprises at least one electric energy storage Device (DS) according to any of the previous claims.

10. Vehicle, characterized in that it comprises at least one electric energy storage Device (DS) according to any one of claims 1 to 8 and/or at least one rechargeable accumulator according to claim 9.

Technical Field

The present invention claims priority from french application 1904184 filed on 19/4/2019, the contents of which (text, drawings and claims) are incorporated herein by reference.

The invention relates to an electrical energy storage device having an electrochemical cell which is of prismatic type and comprises an active part of lithium ion type.

Background

As known to those skilled in the art, in electrochemical cells of the lithium ion type, electrochemical reactions take place which convert chemical energy into electrical energy according to a reversible process. This type of battery includes a porous positive electrode, a porous negative electrode, a porous separator, an electrolyte (of the liquid type or non-aqueous gel type), and a current collector. The positive electrode is typically made of lithiated transition metal oxides and the negative electrode is typically made of graphite.

Such electrochemical cells can be packaged according to four main forms: cylindrical, button cell batteries, prismatic, and flexible bags (or "pouch"). The invention relates more precisely to electrochemical cells of the prismatic, rigid and internal geometry of the type known as "bobino-ercras e". In this type of electrochemical cell, the electrodes and separator are soaked in the electrolyte and arranged to be stacked flat on each other, wound, and then crushed. The electrodes, separator, and electrolyte constitute the active portion (or "jelly roll") where the majority of the heat generated by the electrochemical cell during each charge or discharge is localized.

Usually, this active part is housed in a rigid protective cover (enveloppe), usually made of aluminium (stamped and welded), and is interposed by an electrically insulating cover, for example made of mylar. The protective cover comprises a wall that is placed against a heat exchanger comprised by the electrical energy storage device, said heat exchanger being responsible for draining the heat generated by each electrochemical cell and transferred into the protective cover of said each electrochemical cell.

This heat (or heat loss) is generated both during charging and during discharging, and has at least four sources: ohmic losses (or losses by joule effect) which thermally express the resistance that prevents the passage of current; entropy heat, which represents reversible heat due to entropy change of reactants during an electrochemical reaction occurring in a battery; heat associated with phase change (which is considered negligible compared to the first two terms); and heat due to concentration gradients (which is also considered negligible compared to the first two terms).

Due to the internal geometry (bobino-ercras e) of prismatic electrochemical cells, they have thermal anisotropy, which means that their overall thermal conductivity is not equal in all directions of space and, consequently, the dissipation of the heat generated by them is not equal in all directions of space. There are two main sources of this thermal anisotropy: winding and crushing of the active portion; and the presence of elements in the electrochemical cell (which would impair the thermal diffusion between the active part and the protective cover).

This thermal anisotropy proves problematic because it prevents good control of the internal temperature of the electrochemical cell, which accelerates the aging of the electrochemical cell and limits its performance. In fact, the cooling is carried out by a wall placed against the heat exchanger, which causes a temperature gradient in the electrochemical cell along a direction perpendicular to this wall, along which the thermal conductivity is weak (which is typically about 35Wm-1K-1, whereas the thermal conductivity of the protective casing made of aluminum is about 220 Wm-1K-1).

The object of the invention is therefore, inter alia, to improve the situation.

Disclosure of Invention

To this end, the invention provides, among other things, an electrical energy storage device comprising:

-at least one electrochemical cell for storing electrical energy, the electrochemical cell being prismatic and comprising a lithium-ion active portion housed in a protective casing comprising a first wall made of a material having a first thermal conductivity, the first wall being integral with a second wall; and

-a heat exchanger against which the second wall is disposed and which is responsible for draining the heat generated by the electrochemical cell and transferred into the protective cover.

The storage device is characterized in that at least one of the first walls comprises an insert which extends as far as the second wall and has a second thermal conductivity greater than the first thermal conductivity, and which is responsible for conducting the heat transferred into the first wall towards the second wall (drain).

A much more uniform cooling of the electrochemical cell and thus a much weaker temperature gradient in the electrochemical cell in the direction perpendicular to the second wall than in the prior art electrochemical cells is thereby obtained.

The storage device according to the invention may comprise further features which may be employed individually or in combination, in particular:

in a first embodiment, each insert may be housed in a housing defined in the material of the first wall;

each insert may have a cross-section in a plane parallel to the second wall in the form of a section having a greater width in the vicinity of a first face of the first wall oriented towards the active portion of the electrochemical cell than in the vicinity of a second face of the first wall opposite the first face, so as to tolerate (encaisser) the volume expansion during the charging or discharging of the electrochemical cell;

in a second embodiment, each insert may be fixedly integral with a first face of the first wall oriented towards the active portion of the electrochemical cell;

in the first and second embodiments, each insert may be made of graphite;

in a third embodiment, each insert may be made of a phase change material and housed in a hermetic housing defined in the material of the first wall;

-each electrochemical cell may comprise an electrically insulating cover interposed between the active portion and the protective cover;

the storage means may comprise at least two electrochemical cells coupled in series and/or in parallel, each of said at least two electrochemical cells comprising a second wall disposed against the heat exchanger.

The invention also provides a rechargeable battery comprising at least one electrical energy storage device of the type described above.

The invention also provides a vehicle, optionally of the mobile type, comprising at least one electrical energy storage device of the type described above and/or at least one rechargeable accumulator of the type described above.

Drawings

Other features and advantages of the present invention will become more apparent upon reading the following detailed description and the accompanying drawings, in which:

figure 1 schematically shows an embodiment of an electrical energy storage device according to the invention in a cross-sectional view along the plane YZ,

figure 2 schematically shows in perspective view the main constituent elements of a prismatic electrochemical cell of an electrical energy storage device according to the invention before assembly,

fig. 3 schematically shows, in a cross-sectional view along plane XY, a first embodiment of a protective cover housing the active part of a prismatic electrochemical cell of an electrical energy storage device according to the invention, and

fig. 4 schematically shows, in a cross-sectional view along the plane XY, a second embodiment of a protective cover housing the active portions of a prismatic electrochemical cell of an electrical energy storage device according to the invention.

Detailed Description

The object of the present invention is in particular to provide an electrical energy storage device DS with an electrochemical cell CE of prismatic type and comprising an active part PA of lithium ion (or Li-ion) type, which conducts heat towards a heat exchanger EC of the electrical energy storage device.

In the following, as a non-limiting example, it is considered that the electrical energy storage device DS is used to equip a rechargeable battery, wherein said electrical energy storage device may optionally be coupled in series and/or in parallel with at least one other electrical energy storage device DS. The invention is not limited to this application. In fact, the electric energy storage means DS according to the invention may constitute a rechargeable accumulator.

In addition, in the following, as a non-limiting example, a rechargeable accumulator is considered for equipping a vehicle of the mobile type (for example a car). The invention is not limited to this application. In fact, the rechargeable accumulator comprising at least one electrical energy storage device DS can be used to equip any system, apparatus, device (including industrial devices), building (public or private building) or outside space (public or private outside space). Thus, the rechargeable battery can be used in particular for equipping any type of transport means (land transport means, sea (or river) transport means or air transport means). It is noted that at least one vehicle may comprise at least one electrical energy storage device DS according to the invention and/or at least one rechargeable battery (which comprises at least one electrical energy storage device DS).

An embodiment of an electrical energy storage device DS according to the invention is schematically shown in fig. 1.

As shown on fig. 1, the electrical energy storage device DS according to the invention comprises at least one electrochemical cell CE (of prismatic type) for storing electrical energy and a heat exchanger EC. In the example shown in non-limiting manner on fig. 1, the electrical energy storage device DS comprises four electrochemical cells CE coupled in series, said electrochemical cells being of prismatic type. The electrical energy storage device DS according to the invention may comprise any number of prismatic electrochemical cells CE greater than or equal to one (1). In addition, when the electrical energy storage device DS comprises a plurality of prismatic electrochemical cells CE, these prismatic electrochemical Cells (CE) may be coupled in series and/or in parallel and they are all positioned against the heat exchanger EC.

As shown on figure 2, the prismatic electrochemical cell CE comprises at least one active part PA of the lithium ion type, housed in a protective casing EP.

Although not shown in fig. 2, the active portion PA includes a porous positive electrode, a porous negative electrode, a porous separator, an electrolyte (of a liquid type or a non-aqueous gel type), and a current collector. For example, the positive electrode may be made of lithiated transition metal oxides, and the negative electrode may be made of graphite.

The active fraction PA has an internal geometry of the bobino-ercras type well known to the person skilled in the art and not shown here. The winding direction (i.e., a direction parallel to the long side (or length) of the active part PA) is a direction X, and a direction perpendicular to the winding direction (here, a direction parallel to the short side (or width) of the active part PA) is a direction Y, and a direction Z is perpendicular to the direction X and the direction Y.

The protective shield EP comprises a first wall P1 made of a material having a first thermal conductivity c1, said first wall being integral with a second wall P2. For example, the material is aluminum. The second wall P2 is defined in a plane XY and is placed against (here on) the heat exchanger EC of the (electrical energy) storage device DS. In addition, the second wall P2 is preferably made of the same material as the first wall P1, which is fixedly integral with the second wall (P2). The second wall (P2) is therefore made of aluminium, for example. The first wall P1 is perpendicular to the second wall P2 and is thus disposed in planes XZ and YZ. In addition, each first wall P1 comprises a first (inner) surface F1 oriented towards the active portion PA of the electrochemical cell CE and a second (outer) surface F2 opposite to the first face F1.

The heat exchanger EC is responsible for draining the heat generated by the (each) electrochemical cell CE and transferred into the protective casing EP of this heat exchanger (CE). The heat exchanger comprises, for example, at least one circuit, optionally defined by two plates or by at least one heating pipe (caloduc) in which a cooling fluid circulates.

It is noted that, as shown in a non-limiting manner on fig. 2, the prismatic electrochemical cell CE may comprise supplementary constituent elements. Thus, the prismatic electrochemical cell may comprise a first electrically insulating cover EI1, for example made of mylar, which houses the active part PA (and is therefore interposed between the active Part (PA) and the rigid protective cover EP). The prismatic electrochemical cell may also comprise a second electrically insulating cover EI2, for example made of polymethylmethacrylate (or PMMA), which houses a rigid protective cover EP. The prismatic electrochemical cell may also optionally include a connector CN disposed in contact with the current collector of the active portion PA. The prismatic electrochemical cell may also optionally include a cover CF for placement behind the connector CN and for reclosing the (rigid) protective cover EP and the second electrically insulating cover EI 2.

According to the invention, as shown partially and in a non-limiting manner in fig. 3 and 4, at least one of the first walls P1 (preferably all, as shown) comprises an insert ID that extends up to the second wall P2 and therefore along the direction Z (here, the vertical direction). Each insert ID has a second thermal conductivity c2 that is greater (preferably much greater) than the first thermal conductivity c1 of the material constituting the protective shield EP, and is responsible for conducting the heat transferred into the first wall P1 towards the second wall P2.

For example, the second thermal conductivity c2 may be at least 2 to 10 times the first thermal conductivity c 1.

Due to this high thermal conductivity of the inserts ID, heat is more easily captured by these Inserts (ID) than by the material of the first wall P1 and can therefore be transferred much faster and more efficiently (by draining) into the second wall P2, which is placed against the heat exchanger EC. This thus results in a much more uniform cooling of the (each) electrochemical cell CE and thus a much weaker temperature gradient along the direction Z in the (each) electrochemical cell than in the prior art electrochemical cells. Thus, the thermal anisotropy is significantly reduced, which enables a significant increase of the lifetime of the (each) electrochemical cell CE, while improving the functionality of said electrochemical cell. In addition, the presence of the insert ID does not modify the energy density per unit volume of the electrochemical cell CE. Furthermore, the drainage can also improve the thermal conductivity of the protective hood EP in the directions X and Y.

At least three embodiments of the protective cover EP are contemplated.

In the first embodiment shown on fig. 3, each insert ID may be housed in a housing dedicated to the insert and defined in the material of said first wall P1. To this end, the housing of each insert ID can be created (by removing material) in the material thickness of this wall P1, for example before this wall (P1) is cut/folded/welded to form the boot EP.

For example, each insert ID has a section in a plane XY parallel to the second wall P2 in the form of a section having a greater width in the vicinity of the first face F1 of the first wall P1 (which is oriented towards the active portion PA of the CE of the electrochemical cell) than in the vicinity of the second face F2 of the first wall P1, so as to tolerate the volume expansion during the charging or discharging of the electrochemical cell CE. This alternative configuration serves to ensure the tightness of the rigid protective cap EP in the presence of internal pressure variations. Furthermore, this first embodiment enables the dimensions of the electrochemical cell CE to be unmodified, since the insert ID is integrated in the thickness of the rigid protection casing EP by extending along the direction Z.

In the example shown in non-limiting manner on fig. 3, the insert ID has a section in the plane XY that is trapezoidal, with the long side of the section located in the vicinity of the first face F1 and the short side (parallel to the long side) located in the vicinity of the second face F2. But other forms are contemplated so long as the width is greater in the vicinity of the first face F1 than in the vicinity of the second face F2. For example, the sides having a greater width (which are located near the first face F1) may be rounded and/or the sides having a smaller width (which are located near the second face F2) may be pointed (or angled).

In a second embodiment shown on fig. 4, each insert ID can be fixedly integral with the first face F1 of said first wall P1 (which is oriented towards the active portion PA of the electrochemical cell CE).

In the example shown in non-limiting manner on fig. 4, the insert ID has a section in the plane XY that is trapezoidal, with the long side of the section oriented towards the active portion PA and the short side (parallel to the long side) fixedly integral with the first face F1. But other forms are contemplated as long as the width thereof is smaller in the vicinity of the first face F1 than at the portion facing the active portion PA.

For example, in the first and second embodiments, each insert ID may be made of graphite. But the insert may also be made of graphene or copper, for example.

In a third embodiment (not shown), each insert ID may be made of a phase change material (phase change material from solid to liquid). In the liquid phase, the material has a second thermal conductivity c2 that is much greater than the material has in the solid phase and much greater than the first thermal conductivity c 1. Furthermore, the phase change enables to store energy and thus not to overheat the electrochemical cell CE, since the phase change occurs at a constant temperature. In this case, each insert ID is housed in a hermetic housing defined in the material of said first wall P1.

Each receptacle may be created by removing material in the thickness of wall P1, for example, before this wall (P1) is cut/folded/welded to form the boot EP.

Here, the latent heat of phase change can significantly increase the amount of heat absorbed by the rigid protection shield EP and transferred towards the second wall P2.

For example, the phase change material may be a mineral (or inorganic) compound, such as a hydrated salt. The hydrated salt can be obtained by mixing an organic salt and water, and has an advantage of having a large latent heat so that the material can store or release energy (i.e., state change energy) by a simple state change while maintaining a constant temperature.

This third embodiment enables the dimensions of the electrochemical cell CE to be unmodified, since the insert ID is integrated in the thickness of the rigid protective cover EP by extending along the direction Z.

It is noted that, considering the significant gains provided by the invention in terms of the heat transferred towards the heat exchanger EC, it is expected that the cooling performance of the heat exchanger EC will be reduced.