Cylindrical electric battery cell and corresponding airtight cover.

Abstract

This disclosure relates to a hermetic cover suitable for sealing a cylindrical cell of an electric battery module, said hermetic cover comprising a first annular groove (1) and at least one second annular groove (2), each of the annular grooves being formed in a surface (14) of the hermetic cover, the first annular groove (1) being formed in a first thickness of material (x1) of the hermetic cover (10) below the first annular groove (1) and above a lower base (15) of the hermetic cover (10), at least one second thickness of material (x2) of the surface of the hermetic cover (10) being located below the at least second annular groove (2) and above the lower base (15) of the hermetic cover (10). (Shortcut figure: Figure 2)

Description

Title of the invention: Cylindrical electric battery cell and corresponding airtight cover. Technical field of the invention

[0001] The present description relates to the field of energy storage. The present invention relates to a cylindrical electric battery cell, in particular a hermetic cover adapted for sealing a cylindrical cell of an electric battery module. State of the art

[0002] In many industrial sectors, for example in the field of electric battery modules, it is common practice to design energy storage systems to power various applications. One obstacle encountered by these systems lies in improving safety in the face of the risks associated with the use of cylindrical cells intended to power electric vehicles, particularly with regard to managing stresses within the cells and the risk of damage in the event of failures.

[0003] Cylindrical cells intended for an electric battery module are formed of several elements, including electrodes, typically an aluminum anode coated with graphite and a copper cathode coated with a nickel-manganese-cobalt mixture, referred to herein as "NMC". Between these electrodes lies the electrolyte, which is generally a liquid that allows the transport of ions between the electrodes during the charging and discharging process.

[0004] A cylindrical cell further comprises, at its upper and / or lower base, a cover that closes the cell and ensures its structural stability. A lower cover is typically positioned on the side of the discharging electrode and is designed to maintain the cell's seal, to guarantee airtight separation from the electrolyte, and to prevent leaks while allowing the passage of electric current through metallic connectors.

[0005] Opposite the lower cover, an upper cover is located on the side of the other electrode, with a similar function and allowing an electrical connection with one or more other cylindrical cells of the electric battery module. This upper cover is also adaptable to withstand high internal pressures and to ensure safety in the event of a sudden increase in stresses inside the cell.

[0006] However, and despite the existing safety systems within these known cylindrical cells, a frequently encountered problem is the risk of damage This can occur when these cells are overcharged and / or subjected to excessive temperatures, which can lead to uncontrolled chemical reactions within the battery. Such conditions potentially lead to material expansion and / or gas release within the cylindrical cell, with the resulting increase in internal pressure creating a risk of rupture of the cell casing or its covers, or even a general explosion.

[0007] The existence of such a risk clearly illustrates the limitations of cylindrical cells and existing safety measures. Indeed, the position where a rupture is likely to occur is very difficult to predict in advance. Consequently, there is a need to develop solutions that allow for more effective and secure management of the conditions under which these ruptures occur.

[0008] Object of the invention

[0009] In order to address this or these drawbacks, a hermetic cover suitable for sealing a cylindrical cell of an electric battery module is proposed according to a first object of the present, said hermetic cover comprising a first annular groove and at least a second annular groove, each of said annular grooves being formed in a total thickness of material of the hermetic cover, a first thickness of material of the surface of the hermetic cover being located below the first annular groove and above a lower base of the hermetic cover, at least a second thickness of material of the surface of the hermetic cover being located below the at least second annular groove and above the lower base of the hermetic cover.

[0010] In the present or according to a possible embodiment, the surface of the airtight lid is formed by an upper base, said upper base being substantially parallel to the lower base, the total thickness of material of the airtight lid being located between the lower base of the airtight lid and said upper base. In the present, "substantially parallel elements" means two elements that are parallel with a possible positive or negative variation of an angle from 1° to 3°.

[0011] In the present, measurable quantities will preferably be mentioned in quotation marks, for example, a length "1", an angle "A" or a thickness "x".

[0012] In the present expression, the value of the total material thickness of the airtight lid is a length, this length being measurable vertically from the upper base of the airtight lid to the lower base of the airtight lid. Furthermore, the value of the vertical length defined by the first material thickness of the airtight lid surface is measured vertically between the base of the first annular groove and the base of at least one second annular groove. In addition, The value of the vertical length defined by the second thickness of material on the surface of the airtight lid is measured vertically between the base of at least one second annular groove and the lower base of the airtight lid. When a first and a second annular groove are formed in the airtight lid, the at least second thickness of material on the surface of the airtight lid is necessarily greater than zero, as the base or bottom of at least one second annular groove does not coincide with the lower base of the airtight lid.

[0013] In the present application, a depth is also measurable vertically from the highest point of a groove to the lowest point of the same groove, this measurement being also carried out parallel to the vertical direction used to measure the material thickness of the surface. The width of a groove, for its part, is measured or measurable as the horizontal distance measured from one inner edge of the groove to the other, perpendicular to the direction of measurement of the material thickness of the surface of the airtight lid or the depth mentioned above.

[0014] The aim is thus to provide a hermetic cover designed to direct in a controlled manner any failure to a specific area of ​​the cover in the event of a sudden increase in pressure inside a cylindrical cell of an electric battery module.

[0015] This also makes it possible to channel any potential rupture in a predictable and localized manner, without necessarily seeking to absorb or diffuse the pressure in the event of an explosion. Thanks to the implementation of annular grooves of varying depths on the surface of the cover, controlled zones of weakness are created that promote precise opening under extreme conditions, thus preventing a catastrophic failure while maintaining the overall safety of the system, thereby better protecting users and surrounding equipment.

[0016] According to one embodiment, the ratio of the first material thickness to the second material thickness is greater than or equal to 1.5 and is further less than or equal to 12.

[0017] This allows for optimization of the airtight lid to promote rupture at the first and / or second annular groove. Surprisingly, it has been observed that these ratio values ​​of the first material thickness to the second material thickness provide an airtight lid with maximized precision in controlling the position where a potential failure may occur.

[0018] According to one embodiment, the first thickness is between 30% and 60% of the total material thickness of the airtight lid.

[0019] This ensures that the concentration of the force exerted by the internal pressure is optimally directed towards the first annular groove, promoting a predictable and controlled deformation of the lid in case of failure, for example overpressure likely to damage the cylindrical cell.

[0020] According to one embodiment, the second layer is between 5% and 20% of the total material thickness of the airtight lid.

[0021] This ensures that the point of failure in the event of pressure or internal force applied to the lid is precisely located at the level of at least one second groove designed for this purpose, creating an intentional area of ​​weakness which promotes the failure of the lid at that point and thus further guaranteeing predictable and controlled deformation of the lid in the event of failure, for example an overpressure likely to damage the cylindrical cell.

[0022] According to one embodiment, each of the annular grooves is formed by a respective difference in elevation and by a respective slope of said annular groove, each respective difference in elevation being substantially parallel to the lower base of the airtight cover and each respective slope forming a respective angle of inclination with the lower base of the airtight cover.

[0023] In the present document, and as will be detailed later, the first annular groove comprises, or can be defined by means of, a first slope whose highest point is located at the level of the upper base of the airtight cover and whose lowest point is located at the level of a first corresponding difference in elevation, this first difference in elevation being substantially parallel to the upper base and / or the lower base of the airtight cover. Respectively, the at least one second annular groove comprises, or can be defined by means of, a second slope whose highest point is located at the level of the first difference in elevation (or the difference in elevation of a preceding annular groove) and whose lowest point is located at the level of a second corresponding difference in elevation, this second difference in elevation being substantially parallel to the upper base of the airtight cover, the lower base of the airtight cover, and / or the first difference in elevation.

[0024] This allows the lid structure to be modified so as to direct any potential rupture towards specific areas, improving the predictability of defects and enabling controlled destruction in the event of an increase in internal pressure. Furthermore, the presence of at least two consecutive slopes and at least two consecutive elevation changes allows this configuration to prevent a generalized rupture of the cell enclosure or its lids by concentrating the potential failure on these predetermined areas.

[0025] According to one embodiment, the angle of inclination of the respective slope of at least one second annular groove, called the second angle, is greater than the angle of inclination of the respective slope of the first annular groove, called the first angle.

[0026] This provides a plurality of annular grooves with a structural resistance gradient on or in the airtight lid, the increase in the angle of inclination between the first and second annular groove optimizing the distribution of stresses in the event of an increase in internal pressure.

[0027] This also allows the shape of the annular grooves and the remaining thickness of the airtight lid surface to be optimized so that it is not too large, otherwise the break might not occur at the first and / or at least one second annular groove, and that it is not too small, otherwise the risk of the break occurring there would be increased due to a lesser presence of material from the lid adapted to form this airtight lid surface.

[0028] According to one embodiment, the first angle has a value selected in the range [30°, 60°] and the second angle has another value selected in the range [30°, 60°], said other value being distinct from the value of the first angle.

[0029] This allows for precise control of the direction and potential failure point in the airtight lid in the event of a failure, for example, in the case of overpressure that could compromise the integrity of the cell, by selecting groove angles that optimize structural strength while avoiding damage to the tooling during their formation. By defining the first and second angles within the range [30°, 60°] with distinct values, optimal groove length and inclination are ensured, enabling the prediction and control of the failure location. This avoids problematic extremes, namely excessively acute angles that would make the grooves too long and have less predictable mechanical properties, and excessively obtuse angles that complicate manufacturing with an increased risk of damage during production, particularly with a punching tool.

[0030] According to one possible embodiment, alternatively, the first angle and the second angle each have the same equal value selected in the interval [30°, 60°].

[0031] This allows us to obtain the same advantages as before, but with easier manufacturing of annular grooves since the same manufacturing tool can be used to form grooves having the same angle and desired inclination in the material.

[0032] According to another object of the present, a cylindrical cell is proposed, formed of a cylindrical enclosure and comprising at least one electrode adapted to be connected to an external electrical element, the cylindrical enclosure further comprising a liquid electrolyte, the cylindrical cell further comprising a hermetic lid according to the preceding object and any one of the preceding embodiments, the hermetic lid hermetically closing the cylindrical enclosure.

[0033] This preserves the electrochemical efficiency and safety of the cell by ensuring a seal against any risk of liquid electrolyte leakage. The integration a hermetic cover conforming to the aforementioned annular groove depth and angle specifications, facilitates the control of possible decompressions and / or cell degradation.

[0034] According to one embodiment, the cylindrical cell has dimensions chosen from: a diameter of about 18 millimeters and a length of about 65 millimeters, a diameter of about 21 millimeters and a length of about 70 millimeters, or a diameter between 40 and 50 millimeters and a length less than 125 millimeters.

[0035] In the present, a length of approximately a given number of millimeters is a length to within 1 or 2 millimeters of that given number.

[0036] This makes it possible to provide an optimized solution for applications requiring high energy density and extended autonomy.

[0037] In particular, the specific selection of these diameter values ​​and length values ​​optimizes the advantages provided by the airtight cover for cylindrical cells intended for electric vehicles. By choosing specific dimensions for the cylindrical cell, such as a diameter of 46 millimeters and a length of 99 millimeters, "4680" cells can be used optimally with the airtight cover. These larger dimensions compared to "18650" and "21700" cells offer a greater volume and surface area for energy storage, resulting in a significantly increased maximum capacity. For example, the maximum capacity of "21700" cells can reach 5600mAh, while that of "18650" cells ranges from 2000mAh to 3500mAh.The “4680” cells, with their even larger dimensions, allow for significantly higher capacity and energy density, thus promoting improved performance and longer range for electric vehicles.

[0038] According to another object of the present, an electric battery module comprising at least one cylindrical cell according to the preceding object(s) and any one of the preceding embodiments is proposed.

[0039] This makes it possible to provide a safe and reliable electric battery module by integrating one or more cylindrical cells equipped with hermetically sealed covers designed according to the preceding embodiments. Assembling this cell or these cells within the same module ensures optimal management of the risks of overpressure and extreme temperatures, thanks to the predictability and controllability of the points of failure.

[0040] According to another object of the present document, an electric battery intended to be integrated into an electric motor vehicle is proposed, said electric battery comprising an electric battery module, said electric battery module comprising at least one cylindrical cell according to the preceding object(s) and any one of the preceding embodiments.

[0041] This maximizes the safety and energy efficiency of electric vehicle batteries, since battery system reliability is increased through optimized management of internal stresses and failure risks, while also promoting efficient integration into the diverse architectures of electric vehicles. This also leads to a significant improvement in the overall performance of electric vehicles, both in terms of range and durability. Brief description of the figures

[0042] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the accompanying drawings, on which:

[0043] Fig. 1 illustrates a perspective view of a hermetic cover sealing a cylindrical cell of an electric battery module according to an embodiment of the invention.

[0044] Figure 2 illustrates a first cross-sectional view of annular grooves formed in a airtight lid surface for a cylindrical cell of an electric battery module according to an embodiment of the invention.

[0045] Figure 3 illustrates a second cross-sectional view of annular grooves formed in a airtight lid surface for a cylindrical cell of an electric battery module according to an embodiment of the invention.

[0046] Unless otherwise indicated, common or similar elements in several figures bear the same reference signs and have identical or similar characteristics, so that these common elements are generally not described again for the sake of simplicity. Description of the implementation methods

[0047] Fig. 1 represents a perspective view of a hermetic cover sealing a cylindrical cell of an electric battery module according to an embodiment of the invention.

[0048] As illustrated, a cylindrical cell 100 is shown, intended to be integrated into an electric battery module. The cylindrical cell 100 is closed, and preferably sealed, at its upper base by a hermetic cover 10 which is circular in shape and corresponds to the shape of the upper base of the cylindrical cell 100 in order to close it.

[0049] The cylindrical cell 100 itself is formed of a cylindrical enclosure 110. This cylindrical enclosure 110 comprises at least one electrode (not visible in the drawing), and preferably at least two electrodes, one of which is a cathode and the other a... anode, each of these electrodes being adapted to be connected to an external electrical element. Not visible in the drawing, the cylindrical cell 100 comprises, enclosed inside the cylindrical enclosure 110, a liquid electrolyte, the airtight lid 10 ensuring the sealing and airtightness of the cylindrical cell 100 and, in other words, preventing any leakage of the liquid electrolyte from the cylindrical enclosure 110.

[0050] The airtight lid 10 comprises, in its surface, a plurality of annular grooves of which, presently, a first annular groove 1 and a second annular groove 2.

[0051] Without limitation, and although a plurality of second annular grooves may be envisaged, the embodiments described below refer to the case of a first annular groove 1 and a single second annular groove 2.

[0052] The airtight lid 10 has a predetermined thickness and is made of a given material, this predetermined thickness being located between an upper base 14 of the airtight lid and a lower base of the airtight lid (not visible in [Fig. 1]). The airtight lid 10 further has a predetermined radius “RIO” which is measurable along the surface of its upper base and between the center of the upper base 14 of the cylindrical cell 10 and its edge.

[0053] Alternatively, defining each annular groove as a function of a defined distance from the outer edge of the cylindrical cell and measured along a radius of the surface of the airtight lid 10, the dimensions of the first annular groove 1 and the second annular groove 2 can be defined as follows. The total width of the first annular groove 1 in the upper base 14 of the lid 10 is defined by a first predetermined distance "DI" that separates the two edges of the notch or groove formed by the first annular groove 1. The second annular groove 2 is formed in the depth of the first annular groove 1 and is defined by a second predetermined distance "D2" that separates the two edges of the notch or groove formed by the second annular groove 2.

[0054] According to one possible embodiment, the second predetermined distance “D2” is less than or equal to the first predetermined distance “DI”.

[0055] Without limitation, the dimensions of the cylindrical cell 100, the cylindrical enclosure 110, and / or the airtight lid 10 are diverse and varied. An example of a cylindrical cell is of the "1865" type, where "18" indicates a diameter of 18 millimeters and "65" indicates a length of 65 millimeters. Other examples of cylindrical cells include "2170" or "4680" cells, the latter preferably being used in lithium batteries for electric vehicles.

[0056] According to different embodiments, the material thicknesses defining the airtight lid 10 are therefore adapted so that said airtight lid 10 allows to close and / or seal adequately at least one base of such cylindrical cells, for example the upper base 14.

[0057] In the airtight lid 10, each of the annular grooves 1 and 2 is defined as forming a notch, or groove, which is circular and continuous. Each of the annular grooves has a predetermined depth that follows the curvature of the surface in which it is formed. Formed in the surface of the airtight lid 10, each annular groove has a concave shape including a respective slope and running parallel to the circular contour of the airtight lid 10, but at a defined distance from the outer edge, thus creating a distinct inner circle.

[0058] Fig. 2 represents a cross-sectional view of annular grooves formed in a surface of the airtight cover for a cylindrical cell of an electric battery module according to an embodiment of the invention.

[0059] By way of non-limitation, the case where the airtight lid 10 comprises two annular grooves 1 and 2 is illustrated. This figure also illustrates possible fractions of material thicknesses made in the airtight lid to form the two annular grooves, as well as their respective angles of inclination.

[0060] According to different embodiments, other geometries are possible with different fractions, angles and volumes of matter considered.

[0061] The first annular groove 1 and the second annular groove 2 each have a substantially symmetrical and circular shape, and preferably different dimensions. Each of the grooves is formed in the surface 14 of the airtight lid, the second annular groove 2 being formed in the base of the first annular groove 1.

[0062] According to the embodiment as illustrated, the first annular groove 1 is formed by a first respective drop 12 and by a first respective slope 11, while the second annular groove 2 is formed by a second respective drop 22 and by a second respective slope 21. In this case, a first respective angle of inclination "A1" is defined as forming the angle between the first respective slope 11 and the upper base 14 (or the lower base 15) of the airtight cover 10, while a second respective angle of inclination "A2" is defined as forming the angle between the second respective slope 21 and the upper base 14 (or the lower base 15) of the airtight cover 10.

[0063] The first slope 11 which presents the first annular groove 1 has a summit which coincides with the upper base of the airtight lid 10, while its lowest point is at the level of the first difference in elevation 12. This first difference in elevation 12 is substantially parallel to the lower base 15.

[0064] The height differences 12 and 22, with their respective slopes 11 and 21, have the combined role of better determining the behavior of the lid in the event of internal stress within the cell, which could lead to failure. It is important to strategically position these height differences to optimize pressure distribution, for example in the event of gas expansion inside the cell, and thus to direct any risk of rupture towards predetermined areas where potential damage may occur in the event of failure or explosion.

[0065] According to one embodiment, the airtight lid 10 is made of a material suitable for securely closing and / or sealing the cylindrical cell, in particular at at least one circular opening of such a cylindrical cell.

[0066] As illustrated, the airtight lid 10 has a total thickness of material "x" which forms its main structure, this material preferably being formed at least of the material mentioned above, although other components and / or materials may be incorporated.

[0067] According to one embodiment, at least one of the annular grooves 1 or 2 is formed by machining a volume of material intended to form a cylindrical cell cover. This machining can be carried out using any suitable tool, for example by means of a punch, a punching machine or a drilling tool, to extract material from a solid volume, in order to form a hermetic cover 10 which includes at least one of the grooves in the form of a hollow or a groove.

[0068] The first annular groove 1 and the second annular groove 2 are each formed in a total material thickness "x" of the airtight lid "10". The total material thickness "x" is measurable along a vertical direction, this vertical direction being perpendicular to the surface of the lower base 15 and / or the upper base 14 of the airtight lid 10. As illustrated, the total material thickness "x" equals the sum of three partial material thicknesses "x3", "x1" and "x2".

[0069] According to one embodiment, and with regard to these three partial thicknesses of material "x3", "xl" and "x2", the material of the first thickness of material "xl" is located below the first annular groove 1 and above the lower base 15, which gives the airtight lid 10 significant structural resistance below the first annular groove 1, except at the level of the second annular groove 2 where less material is present.

[0070] In particular, according to one embodiment, material of a second thickness "x2" of the surface of the airtight lid 10 is located below the second annular groove 2 and above the lower base 15. Preferably, the volume of material corresponding to the first thickness of material "xl" forms the lateral edges of the second annular groove 2.

[0071] According to one embodiment, the volume of material corresponding to the third thickness of material “x3” forms the lateral edges of the first annular groove 1.

[0072] Preferably, the volume of material corresponding to the third material thickness "x3" is smaller than the volume of material corresponding to the first material thickness "xl" and / or the volume of material corresponding to the second material thickness "x2". However, the third material thickness "x3" itself is associated with a vertically measurable length that is preferably greater than each of the vertically measurable lengths corresponding to the first material thickness "xl" and the second material thickness "x2".

[0073] According to one embodiment, the ratio of the first material thickness "xl" to the second material thickness "x2", i.e. the value of "xl / x2", is within the interval [1.5; 12].

[0074] For example, it is observed during the design of the annular grooves and the realization of these different relative thicknesses of material that if the first thickness of material "xl" was equal to 1.3 times or to 0.9 times the second thickness of material "x2", it resulted either that the pressure distribution towards the first annular groove was insufficient to guarantee a controlled rupture near it, or that the excessive concentration of force on the second thickness made the integrity of the cover too weak in certain places, in places which are not desired to be points of controlled rupture, thus increasing the risk of unpredictable failure.

[0075] According to one embodiment, the ratio of the first material thickness "xl" to the total material thickness "x" of the airtight lid 10, i.e., the value of "xl / x", is within the range [0.3; 0.6]. In other words, the first material thickness "xl" is between 30% and 60% of the total material thickness "x" of the airtight lid 10.

[0076] For example, it has been observed that after manufacturing annular grooves with different relative material thicknesses, if the first thickness "xl" is only 10% or 25% of the total material thickness "x", then the force distribution is not directed sufficiently towards the first annular groove. In such a case, the accuracy of locating the point(s) of failure is reduced, which could lead to unpredictable deformation of the lid in the event of a failure. Conversely, it has been observed, for example, that if the first thickness "xl" is 70% of the total thickness "x", then the lid may become too rigid in the area of ​​the first thickness, limiting its ability to deform predictably in the event of overpressure, and thus potentially preventing failure at the intended annular groove, which in this case may occur in other parts of the cylindrical cell. The range between 30% and 60% therefore provides an optimal compromise for the value of "xl / x".

[0077] According to one embodiment, the ratio of the first material thickness "xl" to the total material thickness "x" of the airtight lid 10, i.e., the value of "x2 / x", is within the interval [0.05; 0.2]. In other words, the second thickness "x2" is between 5% and 20% of the total material thickness "x" of the airtight lid 10.

[0078] For example, it has been observed that after designing annular grooves and implementing different relative material thicknesses, if the second thickness "x2" is only 1% or 2% of the total material thickness "x", then the airtight lid 10 could exhibit excessive rigidity or hardness compared to areas that would be more advantageously intended to be weak points, which could result in lid failure in one or more undesired areas. Conversely, it has been observed, for example, that if the second thickness "x2" is 30% or 40% of the total material thickness "x", then this configuration could not only prevent a predictable break at the second groove but also negatively affect the functionality of the first groove.A second thickness "x2" therefore risks inappropriately directing the forces at play during overpressure, potentially directing energy in an unforeseen way and compromising the desired failure sequence. The range between 5% and 20% thus provides an optimal compromise for the value of "x2 / x".

[0079] Fig. 3 represents a cross-sectional view of a hermetic cover having annular grooves and similar to those of the previous figure, said hermetic cover being adapted to close or seal a cylindrical cell of an electric battery module according to an embodiment of the invention.

[0080] In particular, different lengths corresponding to the annular grooves formed in the airtight lid are illustrated, including the lengths of the horizontal projections of the respective slopes of these annular grooves and the respective elevation differences of these respective slopes.

[0081] In the present, the horizontal projection of a respective slope of an annular groove is defined as a horizontal distance, more precisely the distance between the highest point and the lowest point of that respective slope when said distance is measured along a horizontal plane, said horizontal plane being defined as a plane parallel to the upper base of the airtight cover of the cylindrical cell.

[0082] Based on the measurable quantities shown in the preceding figures, the first predetermined distance “DI”, the second predetermined distance “D2”, The respective angles of inclination and the respective elevation differences are linked together by several mathematical relationships.

[0083] As illustrated, the distance “RI 1” defines the horizontal projection of the respective slope 11 of the first annular furrow 1. The distance “R12”, which is measurable horizontally without making a horizontal projection, defines the length of the respective elevation difference 12 of the first annular furrow 1. The distance “R21” defines the horizontal projection of the respective slope 21 of the second annular furrow 2. The distance “R22”, which is measurable horizontally without making a horizontal projection, defines the length of the respective elevation difference 22 of the second annular furrow 2.

[0084] From the preceding definitions, it follows that the second predetermined distance, "D2", is equal to the sum of the distances "R21" and "R22". Furthermore, the sum of the distances "RI1", "R12", "R21" and "R22" is equal to the first predetermined distance "DI".

[0085] From the preceding definitions, it also follows that the tangent of the second respective angle of inclination, "A2", that is to say the tangent of the angle which forms the respective slope 21 of the second annular groove 2 with the lower base 15 of the airtight cover 10, is equal to the ratio of the first thickness of material "xl" to the distance "R21".

[0086] Similarly, it follows from the preceding definitions that the tangent of the first respective angle of inclination, “Al”, which forms the respective slope 11 of the first annular groove 1 with the upper base 14 of the airtight lid 10, is equal to the ratio of the third thickness of material “x3” to the distance “RI 1”.

[0087] According to one embodiment, a first annular groove 1 and at least a second annular groove 2 are formable by machining in a volume of total material thickness "x" of a hermetic cylinder cover 10 on the basis of a predetermined selection of values ​​for a plurality of quantities as previously described.

[0088] For example, it is possible to configure a punch press to form the first annular groove 1 and at least one second annular groove 2 from a selection of values ​​for the angles "Al" and "A2", as well as for the distances "R21" and "RI1". In general, it is also possible to configure a punch press to form the first annular groove 1 and at least one second annular groove 2 from a selection of given values ​​for the angles "Al" and "A2", for a choice of material thicknesses from "x", "xl", "x2" and / or "x3" and / or for desired values ​​of the distances "R11" or "R22", etc.

[0089] According to one embodiment, both the first angle “Al” corresponding to the inclination of the respective slope of the first annular groove 1 and the second angle “A2” corresponding to the inclination of the respective slope of the second annular groove 2 are each greater than or equal to 30° and less than or equal to 60°. In this case, preferably, the value of the first angle "Al" is distinct from the value of the second angle "A2".

[0090] For example, choosing the first angle “A1” at 30 degrees and the second angle “A2” at 45 degrees allows for the creation of multiple annular grooves with different structural resistance gradients on the airtight lid. Increasing the angle of inclination between the first and second annular grooves also helps to improve stress distribution in the event of an increase in internal pressure within the cylindrical cell. With a first angle of 30 degrees, the initial slope is gentler, causing the force exerted by the internal pressure to be distributed over a wider area for the same height, resulting in lower initial resistance. The second angle of 45 degrees creates a greater resistance gradient, increasing the efficiency of targeting the location of a controlled failure at the second groove, concentrating the pressure on a smaller area for the same height.Thus, an initial angle of 30 degrees facilitates a gradual transition of pressure towards areas of less resistance, while the second angle of 45 degrees encourages a controlled and targeted break at the level of the second groove.

[0091] By way of example, it is observed that after manufacturing annular grooves respecting different values ​​of angles "Al" and "A2", a value of the first angle "Al" equal to 25° provides the undesirable effect of generating grooves that are too long and thin, thus increasing the risk of uncontrolled breakage under lower loads and complicating the predictability of mechanical properties.

[0092] Conversely, a value of 80° for the angle "Al" leads to a complication of manufacturing, with an increased risk of damage to the punching tool due to the obtuse nature of the angle, making the grooves shorter but requiring a greater punching force and increasing the risk of damage to the material.

[0093] By successive tests, it was thus surprisingly deduced that the interval [30°, 60°] defines the best compromise, not only for the first angle "Al" but also for the second angle "A2", between ease of manufacture and structural resistance, allowing the formation of annular grooves with predictable mechanical properties and controlled localization of the break in case of failure.

[0094] Preferably, the total depth of at least one second annular groove is greater than the total depth of the first annular groove. The second annular groove(s) are formed successively in the direction of the depth of the airtight lid since, if a plurality of second annular grooves are present, these are formed deeper in the airtight lid.

[0095] Finally, the hermetic cover 10, as described in relation to the preceding embodiments, can be used in combination with the cylindrical cell 100 detailed previously. This cylindrical cell 100 is provided with a cylindrical enclosure 110 and electrodes, the whole assembly being able to be integrated into an electric battery module (not shown), itself integrable into an electric battery (not shown). This design ensures not only that the battery meets the high energy requirements of electric vehicles, but also that it provides increased safety and reliability through the integration of controlled rupture strategies, making it particularly advantageous for electric motor vehicles and any other application requiring a high level of reliability and safety.

Claims

Demands

1. Hermetic cover (10) capable of sealing a cylindrical cell (100) of an electric battery module, said hermetic cover (10) comprising a first annular groove (1) and at least a second annular groove (2), each of said annular grooves (1, 2) being formed in a total thickness of material (x) of the hermetic cover (10), a first thickness of material (x1) of the surface (14) of the hermetic cover (10) being located below the first annular groove (1) and above a lower base (15) of the hermetic cover (10), at least a second thickness of material (x2) of the surface of the hermetic cover (10) being located below the at least second annular groove (2) and above the lower base (15) of the hermetic cover (10).

2. Airtight lid (10) according to claim 1, wherein the ratio of the first material thickness (xl) to the second material thickness (x2) is greater than or equal to 1.5 and is further less than or equal to 12.

3. Airtight lid (10) according to claim 2, wherein the first thickness (xl) is between 30% and 60% of the total material thickness (x) of the airtight lid (10).

4. Airtight lid (10) according to claim 2 or 3, wherein the second thickness (x2) is between 5% and 20% of the total material thickness (x) of the airtight lid (10).

5. Airtight cover (10) according to any one of the preceding claims, wherein each of the annular grooves (1, 2) is formed by a respective drop (12, 22) and by a respective slope (11, 21) of said annular groove, each respective drop (12, 22) being substantially parallel to the lower base (15) of the airtight cover (10) and each respective slope (11, 21) forming a respective angle of inclination (A1, A2) with the lower base (15) of the airtight cover (10).

6. Airtight lid (10) according to claim 5, wherein the angle of inclination (A2) of the respective slope (22) of at least a second annular groove (2), called second angle (A2), is greater than the angle of inclination (Al) of the respective slope (12) of the first annular groove (1), called first angle (Al).

7. Airtight lid (10) according to claim 5 or 6, wherein the first angle (A1) has a value selected in the range [30°, 60°] and wherein the second angle (A2) has another value selected in the range [30°, 60°], said other value being distinct from the value of the first angle.

8. Cylindrical cell (100) formed of a cylindrical enclosure (110) and comprising at least one electrode adapted to be connected to an external electrical element, the cylindrical enclosure (110) further comprising a liquid electrolyte, the cylindrical cell (100) further comprising a hermetic lid (10) according to any one of the preceding claims, the hermetic lid (10) hermetically closing the cylindrical enclosure (110).

9. Cylindrical cell (100) according to claim 8, having dimensions selected from: - a diameter of about 18 millimeters and a length of about 65 millimeters, - a diameter of about 21 millimeters and a length of about 70 millimeters, or - a diameter between 40 and 50 millimeters and a length less than 125 millimeters.

10. Electric battery intended to be integrated into an electric motor vehicle, said electric battery comprising an electric battery module, said electric battery module comprising at least one cylindrical cell (100) according to any one of claims 8 to 9.

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