ELECTROCHEMICAL CELL AND BATTERY THEREFOR

Abstract

This electrochemical element (10) for a battery comprises a first electrode (22) of a first polarity, a first terminal (24) of the first polarity, a second electrode (26) of a second polarity, a second terminal (28) of the second polarity, and a casing (40) comprising two walls (42, 44). The casing comprises two first edges (48) and two second edges (50) forming an enclosing quadrilateral (RE). The first terminal (24) of the first polarity and / or the second terminal (28) of the second polarity is arranged entirely inside the enclosing quadrilateral (RE). The two walls each comprise a base sheet made from metal (52) having a thickness (EF) of between 20 μm and 150 μm. The first terminal (24) of the first polarity is arranged in a first corner of the enclosing quadrilateral and the second terminal (28) of the second polarity is arranged in a second corner of the enclosing quadrilateral, different from the first corner.

Description

[0001] TITLE: Electrochemical Element and Corresponding Battery

[0002] The present invention relates to an electrochemical element for a battery, of the type comprising:

[0003] - a first electrode of a first polarity,

[0004] - at least one first terminal of the first polarity,

[0005] - a second electrode of a different polarity,

[0006] - at least one second terminal of the second polarity,

[0007] - an envelope comprising a first wall and a second wall,

[0008] - the envelope comprising two first edges and two second edges, the first and second edges forming an enveloping quadrilateral.

[0009] Electrochemical elements and batteries of W095 / 16283 are known. The electrochemical element disclosed by this document includes terminals arranged in the corners of the electrochemical element.

[0010] The battery made from electrochemical elements includes a plastic casing. The electrochemical element described in this document is used to manufacture rectangular batteries.

[0011] Other electrochemical sets or electrochemical batteries are known from CN 108400385; WO2016 / 205663A1 (EP3311443); KR20160041402A; US10490781 B2 (US20150364729A); CN202373667U; US2013101891A1; WO2012057854A1;

[0012] W02005039013A2 (EP1678804); W003026042A1 (EP1428272); and W09120100A1 (EP0487699).

[0013] The invention aims to provide an electrochemical element with a significant electrical energy storage capacity for a given volume. Furthermore, the electrochemical element should be easy and inexpensive to manufacture and offer high operational reliability.

[0014] To this end, the invention relates to an electrochemical element for the aforementioned battery, characterized in that the first terminal or each of the first polarity and / or the second terminal or each of the second polarity is disposed entirely within the enveloping quadrilateral, in that the first wall and the second wall each comprise a base sheet of metal, the base sheets of metal each having a thickness between 20 pm and 150 pm, in particular between 30 pm and 60 pm, the first terminal of the first polarity is disposed in a first corner of the enveloping quadrilateral and the second terminal of the second polarity is disposed in a second corner of the enveloping quadrilateral, different from the first corner.

[0015] Depending on specific embodiments of the electrochemical element for the battery, it may include one or more of the following characteristics:

[0016] - the first corner and the second corner are adjacent to one of the same first or second edges, in particular the first edges being each a long edge and the second edges being each a short edge;

[0017] - the first two edges are substantially parallel to each other and / or the second two edges are substantially parallel to each other, and in particular substantially perpendicular to the first edges;

[0018] - the electrochemical element comprises exactly one first terminal of the first polarity and one second terminal of the second polarity;

[0019] - the electrochemical element comprises two first terminals of the first polarity arranged in the first corner and a third corner of the enveloping quadrilateral, and two second terminals of the second polarity arranged in the second corner and a fourth corner of the enveloping quadrilateral;

[0020] - either the first corner and the third corner are adjacent corners and the second corner and the fourth corner are adjacent corners, or the first corner and the third corner are opposite corners and the second corner and the fourth corner are opposite corners;

[0021] - the metal sheet of the first wall and the metal sheet of the second wall are formed from a single base metal sheet, the base metal sheet comprising a folded portion forming one of the first or second edges, the other first and second edges being formed by edges of the base metal sheet superimposed and fixed to each other, in particular by heat welding;

[0022] - the metal sheet of the first wall and the metal sheet of the second wall are two individual and separate base metal sheets, each of which has four edges, and in which each of the first and second edges is formed by two edges of the two base sheets superimposed and fixed to each other, in particular by heat welding; and

[0023] - The first terminal(s) of the first polarity and / or each second terminal of the second polarity consists of a superposition of electrode sheets and is unfolded. The invention further relates to a battery of the type comprising a casing and at least one electrochemical element as defined above.

[0024] Depending on specific embodiments of the battery, it may include one or more of the following characteristics:

[0025] - the battery includes a cooling device and the cooling device is adapted to dissipate heat from the electrochemical element, and in particular from a long edge or the edge formed by the folded portion.

[0026] The invention will be better understood upon reading the following description, given solely by way of example and made with reference to the attached drawings, in which:

[0027] [Fig 1] Figure 1 is a schematic front view of a state-of-the-art electrochemical element;

[0028] [Fig 2] Figure 2 is a schematic front view of a battery comprising an electrochemical element according to a first embodiment of the invention;

[0029] [Fig 3] Figure 3 is a front view of the electrochemical element in Figure 2, with one wall of the envelope omitted;

[0030] [Fig 4] Figure 4 is a schematic cross-sectional view of the electrochemical element in Figure 2;

[0031] [Fig 5] Figure 5 is a schematic front view of a battery comprising an electrochemical element according to a second embodiment of the invention;

[0032] [Fig 6] Figure 6 is a front view of the electrochemical element in Figure 5, with one wall of the envelope omitted;

[0033] [Fig 7] Figure 7 is a schematic cross-sectional view of the electrochemical element in Figure 6;

[0034] [Fig 8] Figure 8 is a schematic front view of a battery comprising an electrochemical element according to a third embodiment of the invention, the view being analogous to that of Figure 5; and

[0035] [Fig 9] Figure 9 is a front view of the electrochemical element in Figure 5, with one wall of the envelope omitted, the view being analogous to that of Figure 6;

[0036] In what follows, the expression "front view" refers to a view such as that shown in Figures 1 to 3, 5, 8 and 9.

[0037] Figure 1 shows a schematic front view of a prior art electrochemical element. This electrochemical element 1000 comprises a first electrode of a first polarity 1002, a first terminal of the first polarity 1004, a second electrode of a second polarity 1006, and a second terminal of the second polarity 1008. The electrochemical element 1000 includes an envelope 1010, viewed from the front, which is substantially rectangular in shape and surrounds the first and second electrodes 1002 and 1006. The envelope 1010 thus forms two short edges and two long edges.

[0038] Terminals 1004 and 1008 protrude from envelope 1010 at the center of the short edges.

[0039] The electrochemical element 1000 defines, viewed from the front, therefore in the plane of Figure 1, an EEDT envelope which surrounds the envelope 1010 and the electrodes 1002 and 1006. In this case, the EEDT envelope is a rectangle whose sides extend parallel to the short edges of the envelope 1010, coincide with the free edges of the terminals and coincide with the long edges of the envelope 1010.

[0040] The electrochemical element 1000 therefore leads, when viewed from the front, to a lost space EP, which is free of electrode and terminal and which corresponds to the surface located between the edges of the envelope and, on the one hand, the envelope and, on the other hand, the terminals.

[0041] The following description contains technical features of the invention. These technical features, although presented in a technical context and possibly in combination with other technical features, can each time be used individually, without the other technical features, insofar as this is technically possible.

[0042] In the description of the various embodiments, analogous elements bear the same reference numerals. Also, unless otherwise indicated, each feature described with reference to an embodiment of the invention or to a variant of an embodiment is applicable individually or in any technically feasible combination to the other embodiments or variants.

[0043] Figure 2 shows a battery according to a first embodiment of the invention, designated by the general reference numeral 2. Battery 2 is an electrochemical battery such as is commonly used in electric vehicles. However, other areas of application for battery 2 are conceivable, such as energy storage, electric mobility, aviation, and rail.

[0044] The battery 2 comprises a casing 4 and at least one electrochemical cell 10. In practice, the battery 2 comprises several electrochemical cells 10 connected in series or parallel to obtain the desired voltage and / or capacity. The electrochemical cell 10 is located in the casing 4.

[0045] The casing 4, for example, is parallelepiped-shaped, specifically rectangular, and comprises casing walls, a first terminal 14, and a second terminal 16. The casing walls are more rigid than the walls of the electrochemical element 10 (see below). The battery 2 may include a cooling device, which is not shown in Figure 2 but will be described in more detail in Figures 5 to 9.

[0046] The electrochemical element 10 or each electrochemical element 10 comprises a first electrode of a first polarity 22, a first terminal of the first polarity 24, a second electrode of a second polarity 26, and a second terminal of the second polarity 28.

[0047] The electrochemical element 10 is, for example, of the Lithium-Ion type. The first electrode 22 comprises at least one current collector formed of a metallic strip, for example, of aluminum, coated on at least one side with an active material. For example, in the case of a secondary lithium battery, the first electrode contains an active material which may be a metal oxide comprising lithium atoms, such as lithium cobalt dioxide LCO₂(UC0O₂), NMC (Li₂N₂Mn₂CoI₂). x-y 02), NCA (LiNixCoyAli- x-y 02), LFP (LiFePC), LMO (LiMn2C>4) or similar lithium compounds. The first electrode 22 is, for example, the positive electrode.

[0048] The second electrode 26 comprises at least one current collector formed from a metallic strip, for example copper, coated on at least one side with an active material. For example, in the case of a secondary lithium battery, the second electrode contains an active material which may be a carbonaceous material suitable for inserting lithium atoms, such as graphite, or silicon, LTO (Li4Ti5O2) or TNO (TiNb2O). The second electrode 26 is, for example, the negative electrode.

[0049] The electrochemical element 10 includes a separator, separating the first electrode 22 from the second electrode 26. In the case of a Li-ion electrochemical cell, the separator is permeable to lithium ions but provides electronic insulation. The separator is, for example, a polyolefin membrane.

[0050] Electrochemical element 10 also includes an electrolyte, which can be liquid, such as an organic electrolyte containing lithium salts like LiPF6, solid or gel, such as polymers of Polyvinylidene Fluoride (PVDF) or a copolymer of Polyvinylidene Fluoride and Flexafluoropropylene (PVDF-FIFP).

[0051] The first terminal of the first polarity 24 is electrically connected to the first terminal 14, and the second terminal of the second polarity 28 is electrically connected to the second terminal 16. The terminals are adapted to collect the current from the associated electrode. The first terminal(s) of the first polarity 24 are attached by welding or brazing to the associated current collector or electrode. Similarly, the second terminal(s) of the second polarity 24 are attached by welding or brazing to the associated current collector or electrode. In particular, the first terminal(s) of the first polarity 24 are attached by ultrasonic welding to the associated current collector or electrode. Likewise, the second terminal(s) of the second polarity 28 are attached by ultrasonic welding to the associated current collector or electrode.

[0052] In the case of the embodiment of Figures 2 to 4, the electrochemical element comprises exactly one first terminal of the first polarity 24 and one second terminal of the second polarity 28. In other words, the terminals 24, 28 of the electrochemical element consist of one first terminal and one second terminal.

[0053] The first electrode of the first polarity 22 and the second electrode of the second polarity 26 are flat and surface elements and each contain a support sheet and one or two electrode layers applied to the support sheet.

[0054] The electrochemical element 10, or each electrochemical element 10, comprises a casing 40 having a first wall 42 and a second wall 44. The casing 40 is of the "pouch" type, that is, it has relatively flexible and easily deformable walls. The walls of the casing 40 are therefore more easily deformable and less rigid than the walls of the housing.

[0055] Figure 4 shows the electrochemical element 10 in cross-section along line IV-IV of Figure 2. The housing 4 is omitted in Figure 4.

[0056] The first wall 42 and the second wall 44 each comprise a metal sheet, each having a thickness EF of between 20 µm and 150 µm, in particular between 30 µm and 60 µm. Alternatively, the thickness EF may advantageously be between 60 µm and 100 µm or between 60 µm and 90 µm. The first wall 42 and the second wall 44 may further comprise a coating, for example, of a thermoplastic material, disposed on the metal sheet. For example, the coating is a multilayer film comprising, from the outside in, an electrically insulating and mechanically protective layer, an aluminum sheet, and a layer of polypropylene (PP) and / or acid-modified polypropylene (PPa).Preferably, the envelope is a multilayer film comprising, from outside to inside, a layer of Polyethylene terephthalate (PET), a layer of Nylon, an aluminum foil and a layer of polypropylene (PP) and / or chemically modified polypropylene (PPa - acid modified polypropylene).

[0057] As shown in Figure 2, the envelope 40 comprises two first edges 48, in this case substantially parallel to each other, and two second edges 50, in this case substantially parallel to each other, and in this case substantially perpendicular to the first edges. In this case, each of the first edges is a long edge and each of the second edges is a short edge. The term "short" means that the edge is shorter than each of the long edges, and the term "long" means that the edge is longer than each of the short edges. The first edges 48 are, for example, opposite edges to each other, and the second edges 50 are, for example, also opposite edges to each other. The first and / or second edges 48 and 50 may be substantially straight.

[0058] Alternatively, the first and / or second edges 48 and 50 are not parallel, and form, for example, a trapezoid. Alternatively, the first and / or second edges 48 and 50 are not of different lengths, but of identical length, and therefore form, for example, a square or a rhombus.

[0059] These first and second edges 48 and 50, viewed from the front, generally form a bounding quadrilateral RE, in this case a bounding rectangle (Figure 2), which is defined by the first and second edges 48 and 50 and by the extension of these edges. The edges 48 and 50 coincide with the bounding quadrilateral. The bounding quadrilateral RE has four corners C1, C2, C3, and C4. The four corners C1 to C4 are arranged clockwise in the figures. Depending on the length of the first and second edges 48 and 50 and their arrangement, the bounding quadrilateral RE can also be any quadrilateral, a square, a rhombus, or a trapezoid.

[0060] The first terminal of the first polarity 24 is located in the first corner of the enclosing quadrilateral RE, in this case C1, and the second terminal of the second polarity 28 is located in the second corner of the enclosing quadrilateral, in this case C3. This second corner is different from the first corner. The first corner C1 and the second corner C3 are opposite each other.

[0061] According to the embodiment shown in Figures 2 to 4, the metal sheet of the first wall and the metal sheet of the second wall are two separate, individual base sheets 52, each of which has four edges. Each of the first edges 48 and the second edges 50 is formed by two edges or edge zones of the two base sheets, superimposed and fixed to each other, for example by laser welding or heat welding. This is shown in Figure 4. The enclosure 40 thus comprises four sides formed by a fastening line, in particular a weld line.

[0062] According to the invention, viewed from the front, the first terminal of the first polarity 24 is entirely located within the bounding quadrilateral RE. Furthermore, viewed from the front, the second terminal of the second polarity 28 is entirely located within the bounding quadrilateral RE. In other words, the first and second terminals 24 and 28 are entirely located within a cylinder having a rectangular cross-section of the bounding quadrilateral RE. Each first terminal of the first polarity 24 and / or each second terminal of the second polarity 28 has edges which, viewed from the front, coincide with the bounding quadrilateral RE.

[0063] Figure 3 shows the electrochemical element 10 of Figure 2, also seen from the front, but the first wall 42 of the envelope 40 is omitted.

[0064] The first terminal(s) of the first polarity 24 consist of a superposition of electrode sheets and are unfolded. Similarly, each second terminal of the second polarity 28 consists of a superposition of electrode sheets and are unfolded.

[0065] Figures 5 to 7 show a second embodiment of the battery according to the invention, which differs from the above embodiment only in the following.

[0066] The battery 2 includes a cooling device 20 which is adapted to remove heat from the electrochemical element 10. The cooling device 20 includes, for example, a cooling fluid circuit and means for circulating this cooling fluid.

[0067] The first corner, in which the first terminal of the first polarity 24 is located, and the second corner, in which the second terminal of the second polarity 28 is located, are adjacent to the same first edge 48 or second edge 50. In this case, the first terminal of the first polarity 24 is located in corner C1 and the second terminal of the second polarity 28 is located in corner C4. The two terminals 24 and 28 are therefore adjacent to the same short second edge 50.

[0068] In an unrepresented variant, the first terminal 24 is placed in corner C1 and the second terminal is placed in corner C2.

[0069] Figure 7 shows the electrochemical element 10 in cross-section along line VII-VII of Figure 5. The housing 4 and the cooling device 20 are omitted from Figure 7.

[0070] The metal sheet of the first wall 42 and the metal sheet of the second wall 44 are formed from a single base metal sheet 52. This base metal sheet 52 includes a folded portion 54 forming one of the second edges 50.

[0071] The other second edge 50 and the first edges 48 are formed by overlapping edges of the single base metal sheet, fixed to one another, notably by laser welding or heat welding. The casing 40 therefore comprises three sides formed by a fastening line, in particular a weld line, and one side formed by the folded portion 54.

[0072] In an alternative not shown, the folded portion 54 forms one of the first edges 48. The cooling device 20 is advantageously located on the side of the edge formed by the folded portion 54. This allows the cooling device to be located in a position that is close to the heat generation areas and leads to efficient cooling.

[0073] Figures 8 and 9 show a third embodiment of the battery according to the invention, which differs from the previously described embodiments only by the following.

[0074] The electrochemical element 10 comprises two first polarity terminals 24 arranged in the first corner and a third corner of the enclosing quadrilateral RE. The first two first polarity terminals 24 are fixed and connected to the same current collector of the associated electrode.

[0075] The electrochemical element 10 comprises two second terminals of the second polarity 28 arranged in the second corner and a fourth corner of the enveloping quadrilateral. The two second terminals of the second polarity 28 are fixed and connected to the same current collector of the associated electrode.

[0076] According to a first connection principle, the first two terminals of the first polarity 24 are connected to the same terminal 14 and the second two terminals of the second polarity 28 are connected to the same terminal 16. This variant limits the generation of heat in case of intense current withdrawn from each terminal.

[0077] According to a second connection principle, only one of the first terminals of the first polarity 24 and only one of the second terminals of the second polarity 28 is connected to an individual terminal 14, 16. This variant allows the terminals to be arranged in a way that meets the battery installation requirements where applicable.

[0078] In this embodiment, the first and third corners are adjacent corners such that the first two terminals of the first polarity 24 are adjacent to the same edge, in this case the short edge 50. The first two terminals of the first polarity 24 are arranged in the corners C1 and C4.

[0079] Similarly, the second and fourth corners are adjacent corners, such that the two second terminals of the second polarity 28 are adjacent to the same edge, in this case the short edge 50 opposite the short edge 50 to which the first terminals of the first polarity are adjacent. The two second terminals of the second polarity 28 are located in corners C2 and C3.

[0080] Like the second embodiment shown in Figures 5 to 7, this third embodiment comprises a single base metal sheet. The difference is that the folded portion 54 forms one of the first edges 48. The other first edge 48 and the second edges 50 are formed by overlapping edges of the single base metal sheet, fixed to one another.

[0081] In an alternative not shown, the first and third corners are opposite corners, and the second and fourth corners are opposite corners. In this case, the positions of one of the first terminals 24 and one of the second terminals 28 adjacent to the same long edge 48 in Figures 8 and 9 (for example, the two terminals 24, 28 at the bottom of Figures 8 and 9) are reversed.

[0082] The different embodiments of the battery according to the invention provide the following advantages and technical effects: - Thanks to the metal foil walls, the battery has significant operational safety and a small volume.

[0083] - The battery has a significant amount of energy for a given volume.

[0084] - The battery has a low risk of thermal runaway for a given capacity.

[0085] - The battery is economical to produce and easy to assemble. - In particular, the placement of the terminals in the corners of the casing leads to efficient use of available space and flexibility in terminal arrangement.

[0086] - Also, the diagonal arrangement of the terminals leads to even heat distribution during use. - The battery allows for an efficient cooling system.

Claims

DEMANDS 1. Electrochemical element (10) for battery, of the type comprising - a first electrode of a first polarity (22), - at least one first terminal of the first polarity (24), - a second electrode of a second polarity (26), - at least one second terminal of the second polarity (28), - an envelope (40) comprising a first wall (42) and a second wall (44), - the envelope comprising two first edges (48) and two second edges (50), the first and second edges forming an enveloping quadrilateral (RE), characterized in that the first terminal or each first terminal of the first polarity (24) and / or the second terminal or each second terminal of the second polarity (28) is disposed entirely within the enveloping quadrilateral (RE), in that the first wall and the second wall each comprise a metal base sheet (52), the metal base sheets each have a thickness (EF) between 20 pm and 150 pm, in particular between 30 pm and 60 pm, the first terminal of the first polarity (24) is disposed in a first corner of the enveloping quadrilateral and the second terminal of the second polarity (28) is disposed in a second corner of the enveloping quadrilateral, different from the first corner.

2. Electrochemical element according to claim 1, wherein the first corner and the second corner are adjacent to one of the same first or second edges, in particular the first edges each being a long edge (48) and the second edges each being a short edge (50).

3. Electrochemical element according to any one of claims 1 or 2, in which the first two edges (48) are substantially parallel to each other and / or the second two edges (50) are substantially parallel to each other, and in particular substantially perpendicular to the first edges.

4. Electrochemical element according to any one of claims 1 to 3, in which the electrochemical element (10) comprises exactly one first terminal of the first polarity (24) and one second terminal of the second polarity (28).

5. Electrochemical element according to any one of claims 1 to 3, wherein the electrochemical element (10) comprises two first terminals of the first polarity (24) disposed in the first corner and a third corner of the enveloping quadrilateral (RE), and two second terminals of the second polarity (28) disposed in the second corner and a fourth corner of the enveloping quadrilateral.

6. Electrochemical element according to claim 5, wherein either the first corner and the third corner are adjacent corners (C1, C4) and the second corner and the fourth corner are adjacent corners (C2, C3), or the first corner and the third corner are opposite corners and the second corner and the fourth corner are opposite corners.

7. Electrochemical element according to any one of the preceding claims, wherein the metal sheet of the first wall and the metal sheet of the second wall are formed from a single metal base sheet (52), the metal base sheet comprising a folded portion (54) forming one of the first or second edges, the other first and second edges being formed by edges of the metal base sheet superimposed and fixed to each other, in particular by heat welding.

8. Electrochemical element according to any one of claims 1 to 7, wherein the metal sheet of the first wall (42) and the metal sheet of the second wall (42) are two individual and separate base sheets (52) of metal, each of which has four edges, and wherein each of the first edges and second edges is formed by two edges of the two base sheets superimposed and fixed to each other, in particular by heat welding.

9. Electrochemical element according to any one of the preceding claims, wherein the first terminal or each first polarity terminal (24) and / or each second polarity terminal (28) is made up of a superposition of electrode sheets and is unfolded.

10. Battery of the type comprising a casing and at least one electrochemical element, characterized in that the electrochemical element is an element according to one of the preceding claims.

11. Battery according to claim 10, wherein the battery comprises a cooling device and wherein the cooling device is adapted to remove heat from the electrochemical element and in particular from a long edge or the edge formed by the folded portion.