SENSITIVE SEPARATOR FOR ELECTROCHEMICAL CELL ENABLING REFERENCE POTENTIAL MEASUREMENT
A substrate-based separator device with a partially exposed reference electrode addresses integration issues in electrochemical cells, enabling accurate electrode contribution measurements and enhancing safety and performance.
Patent Information
- Application Number
- FR2023008871
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-08-23
- Publication Date
- 2025-11-14
- Estimated Expiration
- 2043-08-23
AI Technical Summary
Existing methods for integrating a reference electrode in electrochemical cells, such as pouch-type cells, are invasive and uncontrolled, leading to poor reproducibility, mechanical stress, and safety risks like electrolyte leakage and short circuits, while conventional voltage and capacitance measurements do not accurately determine the contribution of each electrode.
A sensitive separator device comprising a substrate, a reference electrode, and a protective layer is introduced between the cathode and anode, with the reference electrode stacked on the substrate and partially exposed for electrical connection, ensuring accurate voltage and capacitance measurements without disrupting cell operation.
The solution provides precise measurements of electrode contributions, enhances safety by preventing electrolyte leakage and short circuits, and maintains mechanical integrity, allowing better battery performance monitoring and utilization.
Smart Images
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Abstract
Description
Title of the invention: SENSITIVE SEPARATOR FOR ELECTROCHEMICAL CELL ENABLING REFERENCE POTENTIAL MEASUREMENT technical field
[0001] The present invention relates to the field of electrochemical cell batteries.
[0002] In particular, the invention relates to the measurement of the capacity and voltage of an electrochemical cell and more specifically of a pouch-type electrochemical cell. Previous techniques
[0003] A pouch-type electrochemical cell comprises a positive electrode called the cathode (discharging), a negative electrode called the anode (discharging), and a porous separator soaked in liquid or gelatinous electrolyte. A flexible pouch encloses the cell, and to prevent a short circuit, a separator is placed between the positive and negative electrodes.
[0004] This configuration allows the implementation of redox chemical reactions which are at the origin of the storage and production of electrons, therefore of electricity.
[0005] A battery pack comprises several modules, themselves composed of several pouch-type electrochemical cells connected in series or in parallel.
[0006] Conventionally, the capacitance and voltage of an electrochemical cell are measured across the positive and negative electrodes. However, this measurement does not allow for the determination of the respective contribution of each electrode. Therefore, the insertion of a third electrode within the cell becomes necessary. This electrode, called the reference electrode, allows for a first measurement of the capacitance and voltage between the reference electrode and the positive electrode, and then a second measurement of the capacitance and voltage between the reference electrode and the negative electrode.
[0007] Reference may be made to document FR 2 986 867 which describes a manufacturing process and an energy storage device using a reference electrode disposed inside the energy storage device.
[0008] Reference may also be made to document FR 3 013 511 which also describes an electrochemical system comprising a comparison electrode which can be positioned at several locations in the cell and in particular inside a separator.
[0009] Reference may also be made to US patent 11,302,955, which proposes the use of a wire reference electrode made of copper and coated with a layer of lithium and conductive polymer. This wire electrode is inserted between the anode and the cathode. This insertion is uncontrolled and invasive, resulting in poor reproducibility of electrode alignment and position, as well as mechanical stresses.
[0010] The use of a reference electrode allows for greater accuracy in measuring the energy delivered by the battery, for knowing the exact contribution of each of the positive and negative electrodes, and thus for monitoring the aging of the electrodes, and for adopting better use of the cell.
[0011] The third electrode must not disrupt the operation of the cell and, for optimal use of this configuration, it is important to take into account certain factors, such as the geometry of the reference electrode, its composition, its location within the cell...
[0012] In addition, the electrical connection of the reference electrode may cause risks of damage to the materials of the separator, which generally include polymer.
[0013] Furthermore, the integration of a reference electrode into a cell can cause safety problems such as electrolyte leakage, short circuits or even gas leakage. Description of the invention
[0014] The present invention aims to overcome these drawbacks.
[0015] The invention therefore relates to an electrochemical cell comprising a cathode, an anode, and a cathode-anode separation device. The separation device comprises a substrate in contact with one of the cathode and anode, a protective layer in contact with the other of the cathode and anode, and a reference electrode positioned between the substrate and the protective layer.
[0016] According to a first design, the substrate is in contact with the cathode, and the protective layer is in contact with the anode. According to a second design, the substrate is in contact with the anode, and the protective layer is in contact with the cathode.
[0017] According to one embodiment, the substrate comprises an electrically insulating and ionically conductive polymer film.
[0018] Advantageously, the substrate comprises an upper surface at least partially in contact with a surface of the reference electrode, and a lower surface in contact with a surface of one of the anode and the cathode extending between 0 and 5 centimeters, preferably between 0 and 3 centimeters, more preferably between 0 and 1 centimeter more than said surface of the anode or cathode in two orthogonal directions.
[0019] According to one embodiment, the electrochemical cell includes an electrical connection, and the reference electrode includes a conductive layer at least partially exposed and made in electrical contact with the electrical connection of the electrochemical cell.
[0020] Advantageously, the protective layer comprises a polymer including polyolefin and / or PTFE and / or PVDF, and includes a surface in contact with a surface of the anode or cathode, said surface allowing the leveling of the separation device.
[0021] Preferably, the reference electrode comprises a stack of an anchor layer, a conductive layer, and a layer with a predetermined electrical potential, said anchor layer being positioned between the substrate and the conductive layer and said conductive layer being at least partially exposed.
[0022] Advantageously, the protective layer comprises a surface in contact with the upper surface of the substrate, a surface in contact with the layer at predetermined electrical potential of the reference electrode, and a surface in contact with the conductive layer of the reference electrode.
[0023] The invention also relates to a battery comprising a set of electrochemical cells as defined above, including a common separation device.
[0024] The invention also relates to a motor vehicle comprising at least one battery as defined above.
[0025] The invention also relates to a method for manufacturing a device for separating the cathode and an anode of an electrochemical cell in a battery. This method comprises at least the following steps: - installation of a substrate comprising a lower surface at least partially in contact with a surface of one of the anode and cathode extending between 0 and 5 centimeters beyond said surface of the anode or cathode in two orthogonal directions, preferably between 0 and 3 centimeters, more preferably between 0 and 1 centimeter beyond said surface of the anode or cathode in two orthogonal directions, - stacking a reference electrode on the substrate, this reference electrode comprising a stack of an adhesion layer, a conductive layer, and a layer with a predetermined electrical potential, said adhesion layer being positioned between the substrate and the conductive layer, the substrate comprising an upper surface at least partially in contact with a surface of the adhesion layer of the reference electrode, with the conductive layer of the reference electrode at least partially exposed, - addition of a protective layer positioned on the substrate and reference electrode assembly, the protective layer comprising a surface in contact with a surface of the anode or cathode allowing the leveling of the separation device, a surface in contact with the upper surface of the substrate, a surface in contact with the layer at predetermined electrical potential of the reference electrode, and a surface in contact with the conductive layer of the reference electrode. Brief description of the drawings
[0026] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:
[0027] - Fig. 1 is a schematic front view of an electrochemical cell of the type pouch including a reference electrode integrated into a separation device
[0028] - Figure 2 is a schematic cross-sectional view of an electrochemical cell of the type pouch including a reference electrode integrated into a separation device
[0029] - Figure 3 schematically represents a sensitive separation device for a pouch-type electrochemical cell;
[0030] - Figure 4 schematically represents the manufacturing process of a device sensitive separation of a pouch-type electrochemical cell;
[0031] - Figure 5 is a schematic side cross-sectional view of the contact electrical of a reference electrode integrated into a separation device;
[0032] - Figure 6 is a schematic front view of the electrical contact of a reference electrode integrated into a separation device; and
[0033] - Figure 7 shows several positioning variants of one or more reference electrodes in a separation device. Detailed description
[0034] Figures 1 and 2 show the general structure of an electrochemical cell 1 of a battery comprising a negative electrode called anode 2, a positive electrode called cathode 3 and a reference electrode 4 integrated in a separation device 5. The anode 2 comprises materials of negative polarity 2b in contact with a collector 2a of the electric currents generated at the anode 2, and the cathode 3 comprises materials of positive polarity 3b in contact with a collector 3a of the electric currents generated at the cathode 3.
[0035] The reference electrode 4 has a predetermined electrical potential under the operating conditions of cell 1.
[0036] Such a configuration allows the measurement of the voltage Vc, between the cathode 3 and the reference electrode 4, and the voltage Va, between the anode 2 and the reference electrode 4. The capacitance of cell 1 can thus be determined. Several other measurements can be taken across the anode 2, the cathode 3, and the reference electrode 4.
[0037] With reference to [Fig.3], the separation device 5 comprises a substrate 8, a reference electrode 4, and a protective layer 9, the reference electrode 4 being positioned between the substrate 8 and the protective layer 9.
[0038] The separation device 5 is positioned between the anode 2 and the cathode 3, the former being in contact with a lower surface A of the substrate 8, and the latter being in contact with a surface B of the protective layer 9. The lower surface A of the substrate 8 extends between 0 and 5 centimeters further than the surface of the anode 2 or the cathode 3, along two orthogonal directions X, Y. Preferably, the lower surface A of the substrate 8 extends between 0 and 3 centimeters, and more preferably between 0 and 1 centimeter further than the surface of the anode 2 or the cathode 3, along two orthogonal directions X, Y. Figure 5 also illustrates the sensitive separation device of an electrochemical cell from a wider perspective.
[0039] The substrate 8 is a rectangular parallelepiped comprising an electrically insulating and ionically conductive polymer film. It also comprises a top surface C which is at least partially in contact with a surface of the reference electrode 4.
[0040] As illustrated in [Fig.3], the reference electrode 4 comprises a successive stack of several layers, including a lower anchoring layer 10, an intermediate conductive layer 11, and an upper layer with a predetermined electrical potential 12, the anchoring layer 10 allowing good adhesion of the conductive layer 11 to the substrate 8.
[0041] The protective layer 9 comprises a polymer including polyolefin and / or PTFE and / or PVDF. It also includes a surface D at least partially in contact with a portion of the upper surface C of the substrate 8, a surface E in contact with the predetermined potential layer 12 of the reference electrode 4, and a surface F in contact with the conductive layer 11 of the reference electrode 4. The surface C of the protective layer 9 is flat and allows for leveling of the separation device 5. Indeed, the protective layer 9 fits perfectly onto the substrate 8 and the reference electrode 4, thus regulating the level differences created by the assembly of the substrate 8 and the reference electrode 4.
[0042] The surface F of the protective layer 9 does not completely cover the conductive layer 11 of the reference electrode 4. Indeed, the separation device 5 has a zone Z4, visible in [Fig.5], essentially made up of the substrate and the conductive layer 11. This arrangement allows the conductive layer 11 to have a bare part used to electrically connect the reference electrode 4.
[0043] Fig. 4 shows the steps in the assembly process of the components forming the sensitive separation device 5 of an electrochemical cell 1.
[0044] The first step E1 consists of installing the substrate 8. The lower surface A of the substrate 8 is placed on a surface of the anode 2 or the cathode 3, and the upper surface C of the substrate 8 is free. The lower surface A is designed to extend between 0 and 5 centimeters beyond the surface of the anode 2 or the cathode 3, along two orthogonal directions X, Y, and more preferably between 0 and 1 centimeter.
[0045] Then, in the second step E2, the different layers of the reference electrode 4, namely the hook layer 10, the conductive layer 11 and then the layer with predetermined electrical potential 12, are stacked on top of the substrate 8. According to one embodiment, the hook layer 10 and the conductive layer 11 are positioned so that one end of the hook layer 10 is superimposed on the central high point of the upper surface C of the substrate 8.
[0046] The conductive layer 11 covers a part of the substrate 8 in the Y direction and its lower end is positioned at the central point of the upper surface C of the substrate 8. The predetermined potential layer 12 is positioned over the conductive layer 11.
[0047] According to one embodiment, the predetermined potential layer 12 is placed on the lower end of the conductive layer 11. The predetermined potential layer 12 does not completely cover the conductive layer 11, and the reference electrode 4 therefore does not cover the entire upper surface C of the substrate 8.
[0048] Finally, in the third step E3, the protective layer 11 is added over the substrate 8 and reference electrode 4 assembly. However, the protective layer 9 does not completely cover the conductive layer 11, so as to leave a portion of said conductive layer 11 exposed. This protective layer 9 is added over the substrate 8 and reference electrode 4 assembly to prevent contact between either the anode 2 or the cathode 3 and said reference electrode 4, and to allow for the leveling of the separation device 5.
[0049] Once the assembly of the separation device 5 has been carried out, a device comprising several zones, with different layer stackings, is obtained, as illustrated in Figures 5 and 6.
[0050] In a first zone Zl, we find the combination of the substrate 8 and the protective layer 9 which allows the passage of ions during the chemical reactions between the anode 2 and the cathode 3.
[0051] In a second zone Z2, all the layers are present, the substrate 8, the three layers of the reference electrode 4, and the protection layer 9. It is in this zone Z2 that the measurement of the local potential is carried out.
[0052] The third zone Z3 comprises the substrate 8, the anchoring layer 10 and the conductive layer 11 of the reference electrode 4, and the protective layer 9. This zone Z3 allows current conduction to the exposed part of the conductive layer 11.
[0053] Finally, in the fourth zone Z4 is the combination of the substrate 8, the anchoring layer 10 and the conductive layer 11 of the reference electrode 4.
[0054] When the separation device 5 is assembled with an electrochemical cell, the exposed part of the conductive layer 11 of the reference electrode 4 is brought into contact with an electrical connection 13 by juxtaposition, and the reference electrode 4 is electrically connected.
[0055] The electrochemical cell 1 also includes a heat-sealing zone 14 and a flexible, waterproof packaging film 15 for wrapping and protecting the connection between said electrical connector 13 and the conductive layer 11 of the reference electrode 4. The juxtaposition between the electrical connector 13 and the conductive layer 11 is maintained by pressure 16 exerted by the protective packaging film 15.
[0056] Furthermore, a weld cannot be made at the connection between the conductive layer 11 of the reference electrode 4 and the electrical connection 13 of the electrochemical cell 1, because the substrate 8 risks being damaged since it is made of polymer materials.
[0057] According to one embodiment, the connector 13 is a connector different from the connectors of the anode 2 and the cathode 3, used specifically for the reference electrode 4. According to another embodiment, the electrochemical cell comprises only the connectors of the anode 2 and the cathode 3, among which at least one is adapted to electrically connect the reference electrode 4.
[0058] Figure 7 shows several embodiments of a separation device 5 according to the invention. One or more reference electrodes 4 can be inserted into a separation device 5, according to several models.
[0059] The first variant V1 is the embodiment described above, with a reference electrode 4 positioned on the upper surface C of the substrate 8, from the central point of the upper surface C to the central high point of the upper surface C.
[0060] The second variant V2 shows an embodiment with five reference electrodes 4 positioned at several points on the upper surface C of the substrate 8.
[0061] The third variant V3 illustrates a grid reference electrode 4 covering a large part of the upper surface C of the substrate 8, and the fourth variant V4 shows an embodiment where two reference electrodes 4 are placed on the upper side, at the ends of the upper surface C of the substrate 8.
[0062] These different configurations allow for flexibility in the way the separation device 5 is constructed. Different measures can be taken at different strategic points of cell 1.
[0063] The separation device 5 between the anode 2 and the cathode 3 has a shape adapted to fit a pouch-type electrochemical cell 1 of the battery, and the risk of electrolyte leakage, gas leakage, or short circuit is avoided. Finally, measurements taken according to the positions of the reference electrode 4, or reference electrodes 4, provide greater accuracy regarding the capacity and voltage that can be delivered by the battery.
Claims
Demands
1. Electrochemical cell (1) comprising a cathode (3), an anode (2) and a cathode (3) and anode (2) separation device (5), characterized in that the separation device (5) comprises a substrate (8) in contact with one of the cathode (3) and anode (2), a protective layer (9) in contact with the other of the cathode (3) and anode (2), and a reference electrode (4) positioned between the substrate (8) and the protective layer (9), said protective layer (9) comprising a surface (B) in contact with a surface of the anode (2) or of the cathode (3), said surface enabling the leveling of the separation device (5).
2. Electrochemical cell (1) according to claim 1, wherein the substrate (8) comprises an electrically insulating and ionically conductive polymer film.
3. Electrochemical cell (1) according to any one of claims 1 and 2, wherein the substrate (8) comprises an upper surface (C) at least partially in contact with a surface of the reference electrode (4), and a lower surface (A) in contact with a surface of one of the anode (2) and the cathode (3) extending between 0 and 5 centimeters beyond said surface of the anode (2) or the cathode (3) in two orthogonal directions (X, Y).
4. Electrochemical cell (1) according to any one of claims 1 to 3, comprising an electrical connection (13), the reference electrode (4) comprising a conductive layer (11) at least partially exposed and electrically contacted with the electrical connection (13) of the electrochemical cell (1).
5. Electrochemical cell (1) according to any one of claims 1 to 4, wherein the protective layer (9) comprises a polymer comprising polyolefin and / or PTFE and / or PVDF, and comprises a surface (B) in contact with a surface of the anode (2) or cathode (3), said surface enabling the leveling of the separation device (5).
6. Electrochemical cell (1) according to any one of claims 1 to 5, wherein the reference electrode (4) comprises a stack of a tethering layer (10), a conductive layer (11), and a layer with a predetermined electrical potential (12), said tethering layer (10) being positioned between the substrate (8) and the conductive layer (11) and said conductive layer being at least partially exposed.
7. Electrochemical cell (1) according to claim 6, wherein the protective layer (9) comprises a surface (D) in contact with the upper surface (C) of the substrate (8), a surface (E) in contact with the layer with predetermined electrical potential (12) of the reference electrode (4), and a surface (F) in contact with the conductive layer (11) of the reference electrode (4).
8. Battery comprising a set of electrochemical cells (1) including a common separation device (5), according to any one of claims 1 to 7.
9. Motor vehicle comprising at least one battery according to claim 8.
10. A method for manufacturing a device for separating (5) a cathode (3) and an anode (1) of an electrochemical cell (1) of a battery, characterized in that it comprises at least the following steps: • installation of a substrate (8) comprising a lower surface (A) at least partially in contact with a surface of one of the anode (2) and the cathode (3) extending between 0 and 5 centimeters beyond said surface of the anode (2) or the cathode (3) in two orthogonal directions (X, Y), • stacking a reference electrode (4) on the substrate (8), this reference electrode (4) comprising a stack of a tack layer (10), a conductive layer (11), and a layer with a predetermined electrical potential (12), said tack layer (10) being positioned between the substrate (8) and the conductive layer (11),the substrate (8) comprising an upper surface (C) at least partially in contact with a surface of the bonding layer (10) of the reference electrode (4), the conductive layer (11) of the reference electrode (4) being at least partially exposed, • addition of a protective layer (9) positioned on the assembly of the substrate (8) and the reference electrode (4), the protective layer (9) comprising a surface, (B) in contact with a surface of the anode (2) or cathode (3) allowing the leveling of the separation device (5), a surface (D) in contact with the upper surface (C) of the substrate (8), a surface (E) in contact with the layer with predetermined electrical potential (12) of the reference electrode (4), and a surface (F) in contact with the conductive layer (11) of the reference electrode (4).