Lid assembly for a prismatic battery cell having an improved sealing

Abstract

There is described a lid assembly (1) for a prismatic battery cell having a casing (2) which internally defines an inner compartment (3) and comprising: a base plate (4) configured to close the inner compartment (3); a current collector (5) configured to be electrically connected to a respective electrode of the battery cell; a terminal member (6) electrically connected with the current collector (5); and a sealing assembly (12) configured to define a fluid-tight seal between the inner compartment (3) and an outer environment; the sealing assembly (12) comprises: a first sealing member (13) interposed between the current collector (5) and the base plate (4) for fluid-tightly preventing an outflow of said electrolytic material from the inner compartment (3); and a second sealing member (14) interposed between the terminal member (6) and the base plate (4) for fluid-tightly preventing an inflow of an external fluid from the outer environment towards the inner compartment (3).

Description

[0001] LID ASSEMBLY FOR A PRISMATIC BATTERY CELL HAVING AN

[0002] IMPROVED SEALING

[0003] TECHNICAL FIELD

[0004] The present invention relates to a lid assembly for a prismatic battery cell , in particular a lid assembly for closing and sealing in a fluid-tight manner an inner compartment of a prismatic battery cell housing electrodes and electrolytic material .

[0005] BACKGROUND ART

[0006] Battery cells are known, which are used as electrical energy accumulators .

[0007] In particular, so-called primary batteries are known, which cannot be easily recharged and are therefore destined to single-use , and so-called secondary batteries are known, which can be repeatedly charged after each cycle of usage .

[0008] Single-cell batteries of the secondary type are known which are used for various portable small-si zed electronic devices , such as cellular phones , watches , smartwatches , smartbands , etc .

[0009] Also , batteries which include a plurality of cells connected in series or in parallel are known, for example as used in the automotive industry .

[0010] The present invention will refer to a battery cell for the use in a battery of a hybrid or full electric vehicle , without however losing generality .

[0011] Secondary battery cells can be manufactured as various types , such as cylindrical or prismatic cells .

[0012] The present invention will refer to prismatic battery cells , without however losing generality .

[0013] A prismatic battery cell typically comprises a hollow prismatic casing, for example in the shape of a parallelepiped and usually made of metallic material , and two electrodes ( cathode and anode ) housed within the casing, which then defines an inner compartment of the cell .

[0014] The compartment also houses a separator material electrically interposed between the two electrodes .

[0015] Within the compartment , the electrodes and the separator are immersed in an electrolytic solution, usually liquid or gelatinous .

[0016] The battery cell also comprises at least one lid assembly which is coupled to the casing for closing the compartment .

[0017] More speci fically, the casing usually has at least one ( rectangular ) opening, normally located on its top, through which the electrodes , separator and electrolytic solution are inserted into the compartment . The lid assembly is coupled to the casing for closing such opening .

[0018] The lid assembly typically comprises :

[0019] - a base plate , typically metallic, arranged to match and engage the opening of the casing for the closing thereof ;

[0020] - a current collector member for each electrode , which is electrically connected to the relative electrode and is configured to collect the electric energy form such electrode and feed it from the inner compartment towards the outside environment ; and

[0021] - a terminal member for each electrode , which is electrically connected with the respective col lector member for receiving the electric energy therefrom, and which is configured to receive a connector of a consumer device which has to be powered by the battery cell .

[0022] The terminal member and the col lector member are usually coupled ( electrically and mechanically) with one another via a terminal pin, which engages a respective through hole obtained in the base plate .

[0023] That is , the terminal member is arranged on a first external side of the base plate , whereas the collector member is arranged on a second internal side of the base plate , opposite the first side .

[0024] The lid assembly further comprises a seal element for each collector member, which is made of resilient and electrically insulating material and which serves the twofold function of : electrically insulating the collector member from the base plate and f luid-tightly sealing the inner compartment of the casing from the outside environment .

[0025] To this end, the seal element is mechanically interposed between the respective collector member and the base plate , so that the collector member and the base plate are not arranged in direct contact with one another, but still being mutually coupled only via the seal element itsel f .

[0026] In some configurations , the casing has two openings , one for each electrode , for example two lateral openings . In this case , the battery has two lid assemblies , one for each electrode and each having its respective base plate , a single terminal member, a single collector member, and a single seal element .

[0027] In light of the above , the lid assembly seals the inner compartment in a fluid-tight manner .

[0028] Generally, the seal element is defined by a simple o-ring .

[0029] According to a known operative configuration, the battery cell may be immersed in a cooling fluid, such as thermally controlling oil , during normal operation, for ensuring a nominal operating temperature of the battery cell .

[0030] Hence , the seal element must also ensure a fluid- tight sealing of the inner compartment for avoiding the cooling fluid entering the inner compartment .

[0031] Generally, the seal element is made of FKM, i . e . fluorine rubber . However, the Appl icant has observed that FKM seal elements tend to swell when in contact with the electrolytic material contained inside the inner compartment , which swelling is detrimental to the nominal functioning of the seal element itsel f .

[0032] In some other known solutions , the seal element is made of resinous material . However, the Applicant has noted how the resinous material has a low resistance to shear forces , which results in a reduced li fespan of the seal element itsel f .

[0033] A need is felt in the sector to further improve the known lid assembl ies for battery cells , especially as per their fluid-thigh sealing ef fectiveness , their electric insulation ef fectiveness , the resistance of their seal element to the compressive and shear forces acting thereon and the li fespan of the seal element thereof .

[0034] DISCLOSURE OF INVENTION

[0035] It is therefore an obj ect of the present invention to provide a lid assembly for a prismatic battery cell which is designed to overcome at least one of the above- mentioned drawbacks in a straightforward and low-cost manner .

[0036] This obj ect is achieved by a lid assembly as claimed in the appended independent claim 1 . Preferred embodiments of the present invention are laid down in the appended dependent claims .

[0037] BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings , in which :

[0039] Figure 1 is an exploded perspective view, with parts removed for clarity, of a lid assembly for a prismatic battery cell according to the present invention;

[0040] Figure 2 is a larger-scale exploded lateral and partially sectioned view, with parts removed for clarity, of a terminal area of the lid assembly of Figure 1 ;

[0041] Figure 3 is a sectioned view, with parts removed for clarity, of the terminal area of Figure 2 in an assembled configuration;

[0042] Figure 4 is a sectioned view of a first seal ing member of the lid assembly;

[0043] Figure 5a is a sectioned view of a second sealing member of the lid assembly; and

[0044] Figure 5b is a sectioned view of a second seal member of the lid assembly according to an alternative embodiment thereof . BEST MODE FOR CARRYING OUT THE INVENTION

[0045] With reference to Figure 1 , number 1 indicates as a whole a lid assembly for a prismatic battery cell .

[0046] In particular, the battery cell is of the prismatic type and has a hollow prismatic casing 2 which internally defines an inner compartment 3 with an opening 3a to access inner compartment 3 .

[0047] According to the embodiment shown, casing 2 has a parallelepiped shape . However, casing 2 could have any prismatic shape , such as cubic, triangular-based, etc .

[0048] In one embodiment , casing 2 could be cylindrical .

[0049] The present invention will refer to a prismatic battery cell , without however losing generality .

[0050] In particular, the present invention will refer to a battery cell for use in the automotive industry, for example in a battery module of a hybrid or full-electric vehicle , without however losing generality .

[0051] The battery cell further comprises electrodes ( cathode and anode , not shown) , which are housed in inner compartment 3 together with separator material (not shown) and an electrolytic material (not shown) .

[0052] The electrolytic material may be liquid or gelatinous .

[0053] The electrodes and the separator material are inserted into inner compartment 3 from opening 3a . Accordingly, lid assembly 1 is configured to be coupled with casing 2 at opening 3a for f luid-tightly closing inner compartment 3 , as required during the normal use of the battery cell .

[0054] Hence , the battery cell comprises casing 2 , with the electrodes , the separator and the electrolytic solution, and lid assembly 1 .

[0055] Furthermore , the battery cell is configured to be immersed, in use , in a cooling fluid configured for cooling the battery cell during the operation thereof .

[0056] In detail , the battery cell is preferably part of a battery module including a plurality of battery cells connected to one another in parallel . The module has an external housing encapsulating the battery cells . The cooling fluid is recirculated, in use , within the housing so as to lap the battery cells and cool them by heat exchange .

[0057] In light of the above , it is necessary to fluid- tightly seal each inner compartment 3 in order to avoid the electrolytic material to outflow therefrom and in order to avoid the cooling fluid to flow therein .

[0058] With reference to Figures 1 and 2 , lid assembly 1 essentially comprises : a base plate 4 , made of metallic material , preferably aluminum, for closing opening 3a of inner compartment 3 , namely arranged to match the shape of , and engage , opening 3a ;

[0059] - a current collector 5 configured to be electrically connected to a respective electrode of the battery cell within inner compartment 3 for collecting electrical energy therefrom and trans ferring it from inner compartment 3 outwards ;

[0060] - a terminal member 6 electrically connected with collector 5 for receiving the electrical energy therefrom and configured to be electrically coupled with a connector (not shown) of a consumer device (not shown) which has to be powered by the battery cell .

[0061] Preferably, collector 5 is shaped as a plate body for electric connection with the respective electrode , according to a manner known and not described in detail .

[0062] Preferably, lid assembly 1 further comprises a pin member 7 coupling mechanically, and connecting electrically, terminal member 6 with collector 5 .

[0063] In detail , pin member 7 has a substantially cylindrical shape .

[0064] In detail , in an operative assembled configuration of lid assembly 1 partially shown in Figure 3 , pin member 7 proj ects from collector 5 , preferably orthogonally .

[0065] Opportunely, base plate 4 has a through hole 4a, an inner wall 4b configured to face inner compartment 3 ( in the assembled configuration, see Figure 3 ) and an outer wall 4c opposite inner wall 4b and configured to face an outer environment external to the inner compartment 3 .

[0066] Pin member 7 engages through hole 4a so as to orthogonally protrude from outer wall 4c and so that a surface 5a of collector 5 from which pin member 7 proj ects faces inner wall 4b ( Figures 1 and 2 ) .

[0067] Terminal member 6 is mechanically coupled to pin member 7 , so as to establish said electric connection .

[0068] In detail , terminal member 6 has a through hole 6a engaged ( in contact ) by pin member 7 , until terminal member 6 rests on outer wall 4c, conveniently with the interposition of an electrically insulating gasket 8 , so that terminal member 6 and base plate 4 are electrically insulated from one another . Opportunely, also gasket 8 includes a trough hole 8a for allowing the passage of pin member 7 .

[0069] Pin member 7 extends along an axis A and through holes 4a, 6a and 8a are expediently coaxial with pin member 7 .

[0070] Hence , terminal member 6 faces outwards , for receiving the aforementioned connector, and is electrically insulated from base plate 4 (by gasket 8 ) , in order to avoid a current dispersion thereon or a short circuit . Conveniently, lid assembly 1 further comprises :

[0071] - a stop frame 10 made of an electrically insulating material ( such as rigid plastic ) , known per se and not described in detail ;

[0072] - a pour opening I la obtained in base plate 4 through which the electrolytic material is to be inserted; and

[0073] - a cap 11b for closing pour opening 13a .

[0074] Lid assembly 1 further comprises a sealing assembly 12 configured to define a fluid-tight seal between inner compartment 3 and the aforementioned outer environment .

[0075] According to an aspect of the present invention, sealing assembly 12 comprises :

[0076] - a first sealing member 13 which is (mechanically) interposed between collector 5 and base plate 4 for fluid- tightly preventing an outflow of said electrolytic material from inner compartment 3 ; and

[0077] - a second sealing member 14 which is (mechanically) interposed between terminal member 6 and base plate 4 for f luid-tightly preventing an inflow of an external fluid, and in particular an inflow of the aforementioned cooling fluid, from the outer environment towards inner compartment 3 .

[0078] In detail , and with respect to an outward direction going from collector 5 towards terminal 6 ( that is , when lid assembly 1 is coupled to casing 2 , from inner compartment 3 towards the outer environment ) , first sealing member 13 is arranged in an innermost position with respect to second sealing member 14 .

[0079] In greater detail , second sealing member 14 is closer to the outer environment than first sealing member 13 .

[0080] In this regard, f irst sealing member 13 is configured to be lapped by the electrolytic material which may leak, in use , from inner compartment 3 , and is configured to prevent second sealing member 14 from being contacted by the electrolytic material .

[0081] Similarly, second sealing member 14 is configured to be lapped by the cooling fluid which may leak, in use , from the outer environment , and is configured to prevent first sealing member 13 from being contacted by the cooling fluid .

[0082] Thanks to the double seal configuration of sealing assembly 12 , i . e . thanks to the presence of first sealing member 13 dedicated to f luid-tightly stop the electrolytic material and of second sealing member 14 dedicated to f luid-tightly stop the cooling fluid, the fluid-tight sealing properties of lid assembly 1 are signi ficantly improved .

[0083] According to the non-limiting embodiment shown in the appended Figures , first sealing member 13 and second sealing member 14 define two distinct and separate components with solution of continuity .

[0084] That is , sealing assembly 12 comprises two distinct and separate parts or pieces , defined respectively by first sealing member 13 and second sealing member 14 .

[0085] Preferably, as visible in figures 1 and 2 , first sealing member 13 and second sealing member 14 have an annular shape and define , each, a through hole engaged by pin member 7 .

[0086] In detail , first sealing member 13 and second sealing member 14 are arranged coaxial with axis A.

[0087] According to an alternative embodiment not shown, first sealing member 13 and second sealing member 14 may have a rectangular or squared conformation, still including however the aforementioned through hole engaged by pin member 7 .

[0088] As visible in Figure 3 , in which the assembled configuration of lid assembly 1 is shown, and considering the above-described assembled conf iguration, lid assembly 1 internally defines a first space 15 delimited between base plate 4 and collector 5 and a second space 16 delimited between terminal member 6 and base plate 4 .

[0089] In detail , first space 15 and second space 16 are fluidically connected with one another, thereby defining an air gap 17 within lid assembly 1 .

[0090] First space 15 i s engaged by first sealing member 13 , so that first sealing member 13 is ( axially, relative to axis A) pressed against base plate 4 and collector 5 .

[0091] Second space 16 is engaged by second sealing member

[0092] 14 , so that second sealing member 14 is ( axially, relative to axis A) pressed between terminal member 6 and base plate 4 .

[0093] Moreover, first sealing member 13 and second sealing member 14 are advantageously pressed in contact against one another ( substantially radially, relative to axis A) so as to f luid-tightly close air gap 17 .

[0094] In this way, fluid-tight sealing between inner compartment 3 and the outer environment is ef fectively ensured, without overfilling air gap 17 , which could be detrimental to the structural stability and functioning of lid ass emb 1 y 1 .

[0095] As it is known, the electrolytic material is of polar nature , i . e . it is a polar medium, i . e . it is a material containing a nonvanishing dipole moment .

[0096] Conversely, the cooling fluid is expediently of nonpolar nature , i . e . it is a nonpolar medium, i . e . it does not possess regions of positive and negative charge .

[0097] To this end, according to an aspect of the present invention, first sealing member 13 comprises a nonpolar material at least at an outer surface thereof , so that the outer surface is completely defined by the nonpolar material .

[0098] Conversely, second sealing member 14 comprises a polar material at least at an outer surface thereof, so that the outer surface is completely defined by the polar material .

[0099] Preferably, first sealing member 13 is made of EPDM rubber at least at the outer surface thereof.

[0100] In one embodiment, first sealing member 13 is completely made of a nonpolar material, preferably EPDM rubber .

[0101] Preferably, second sealing member 14 is made of NBR rubber or HNBR rubber at least at the outer surface thereof .

[0102] In one embodiment, second sealing member 14 is completely made of a polar material, preferably NBR rubber or HNBR rubber.

[0103] In light of the above, the electrolytic material, i.e. a polar medium, is sealed by, and with, a nonpolar material (e.g. EPDM rubber) , whereas the cooling fluid, i.e. a nonpolar medium, is sealed by, and with, a polar material (e.g. NBR rubber or HNBR rubber) .

[0104] Thanks to this configuration, the sealing properties of lid assembly 1 are even more significantly improved, especially compared to the known prior art solution whereby the polar electrolytic material is sealed with FKM or resin, which are polar materials .

[0105] In fact , when a polar material interacts with a nonpolar material , their contact behavior is improved because , chemically, like dissolves like .

[0106] Accordingly, the Applicant has observed that when a polar medium is sealed by a nonpolar material , and vice- versa, the sealing properties are largely improved .

[0107] In other words , lid assembly 1 according to the present invention and including a sealing assembly 12 with dedicated sealing functions allows to separate the outward and inward sealing functions , in order to ef fectively provide media separation and electro-chemical compatibility thereof .

[0108] Accordingly, the li fespan of sealing assembly 12 is increased .

[0109] According to an alternative embodiment not shown of the lid assembly 1 according to the present invention, first sealing member 13 and second sealing member 14 are fixed to one another via a carrier member (not shown) .

[0110] In practice, according to such alternative embodiment , sealing assembly 12 is defined by a single component made of three pieces coupled to one another .

[0111] More precisely, first sealing member 13 is coupled to the carrier member and the carrier member is coupled to second sealing member 14 . The carrier member is preferably made of rigid thermoplastic material .

[0112] The Applicant has observed that such configuration of sealing assembly 12 has a good structural stability and is particularly advantageous from an assemblability point of view, without being detrimental to manufacturing . In this regard, having to handle a single component during assembling of lid assembly 1 eases the assembling process thereof .

[0113] However, given the fact that first sealing member 13 and second sealing member 14 are made of materials of a profoundly di f ferent nature , the production in series thereof as a one-piece component may be di f ficult .

[0114] The presence of the carrier member avoids the above , albeit ensuring a good assemblabil ity of sealing as sembly 12 and of lid assembly 1 .

[0115] According to a further alternative embodiment not shown of the lid assembly 1 according to the present invention, first sealing member 13 and second sealing member 14 are made in one single piece without solution of continuity .

[0116] More speci fically, first sealing member 13 and second sealing member 14 define two j oined sealing portions of sealing assembly 12 , so that sealing as sembly 12 comprises only one single piece without solution of continuity .

[0117] The Applicant has observed that such embodiment is particularly advantageous since it ensures that first sealing member 13 and second sealing member 14 are always in contact with one another , since they are made in one single piece .

[0118] Hence , lid assembly 1 is made more stable and reliable from a sealing point of view .

[0119] Moreover, the total number of components of lid assembly 1 is reduced .

[0120] Thanks to the various possible embodiments of lid assembly 1 described above , it is clear that , depending on the geometry of lid assembly 1 and of its components , such as terminal member 6 , base plate 4 , collector 5 and stop frame 10 , and depending on the production needs and capacities , a sealing assembly 12 according to one of the aforementioned embodiments may be chosen, i . e . a single piece sealing assembly, a two separate pieces sealing assembly, or a two separate , but j oined, pieces sealing assembly .

[0121] Each of these embodiments allows to obtain the above- mentioned respective advantages and technical ef fects .

[0122] Advantageously, second sealing member 14 has an annular shape about axis A and has a semi-profile with a non-symmetrical cross-section, relatively to the axial direction .

[0123] It is speci fied that the term "annular" does not necessarily imply that second sealing member 14 has a circular or substantially circular conformation .

[0124] In fact , as already speci fied above , in an alternative embodiment not shown, second sealing member 14 may have a rectangular or squared conformation, but still annularly extending about axis A due to the presence of the respective through hole engaged by pin member 7 .

[0125] Hence , the term "annular" it is to be intended as "extending about / around axis A" , regardless of the shape of second sealing member 14 .

[0126] More speci fically, according to a first preferred embodiment visible in Figure 5a, the semi-prof ile of second sealing member 14 has a lobed cross-section shaped so as to include a first lobe 18a and a second lobe 18b protruding from the first lobe 18a .

[0127] In particular, first lobe 18a is arranged in a radially outer position with respect to second lobe 18b, relatively to axis A.

[0128] More in particular, first lobe 18a defines a first annular lip of second sealing member 14 and second lobe 18b defines a second annular lip of second sealing member 14 .

[0129] Conveniently, first lobe 18a has a radial si ze larger than the radial si ze of second lobe 18b , along the radial direction with respect to axis A.

[0130] Preferably, first lobe 18a and second lobe 18b have the same axial si ze , relative to axis A.

[0131] Preferably, second lobe 18b is pressed in contact against first sealing member 13 .

[0132] Expediently, first lobe 18a is compressed between terminal member 6 and base plate 4 .

[0133] The Applicant has noted that the aforementioned configuration of second sealing member 14 ( Figure 5a ) ensures the optimal deformability of second sealing member 14 in order to appropriately fill second space 16 and in order to ef fectively ensure a stable contact with first sealing member 13 during use , thereby ensuring a stable and durative fluid-tight sealing of air gap 17 .

[0134] The sealing of air gap 17 is in fact very important in order to avoid the nonpolar cooling fluid to interact with the nonpolar first sealing member 13 and the polar electrolytic material to interact with the polar second sealing member 14 .

[0135] According to an alternative second preferred embodiment visible in Figure 5b, the semi-prof ile of second sealing member 14 has a D-shaped cross-section with a perimeter 19 including a substantially straight section 19a, which extends substantially parallel to axis A, and a curve section 19b which j oins the two ends of straight section 19a and faces axis A.

[0136] In particular, straight section 19a defines a radially outermost annular lateral wall of the D-shaped second sealing member 14 , whereas curve section 19b defines a radially innermost annular lateral wall of the D-shaped second sealing member 14 .

[0137] The Applicant has observed that such D-shaped second sealing member 14 has an improved structural robustness , while ensuring a satis factory level of deformability .

[0138] As visible in Figures 1 to 3 , and in particular in Figure 4 , first sealing member 13 presents a substantially L-shaped semi-profile with respect to axis A.

[0139] More speci fically, a transversal cross-section of first sealing member 13 results in two L-shaped semiprofiles radially opposite to one another with respect to axis A.

[0140] In detail , first sealing member 13 comprises :

[0141] - an axial collar 20 extending annularly about axis A and configured to electrically insulate pin member 7 from base plate 4 ; and

[0142] - a radial sealing portion 21 protruding from the collar 20 in a cantilevered manner and configured to f luid-tightly seal inner compartment 3 .

[0143] In detail , sealing portion 21 is ( axially) compressed between inner wall 4b of base plate 4 and surface 5a of collector 5 .

[0144] It is speci fied that the term "annular" or "annularly" does not necessarily imply that first sealing member 13 has a circular or substantially conformation .

[0145] In fact , as already speci fied above , in an alternative embodiment not shown, first sealing member 13 may have a rectangular or squared conformation, but still annularly extending about or around axis A due to the presence of the respective through hole engaged by pin member 7 .

[0146] Hence , the term "annular" it is to be intended as "extending about axis A" , regardless of the shape of first sealing member 13 .

[0147] Advantageously, sealing portion 21 includes a main body 22 and a bulge or bump 23 extending from the main body 22 and defining a free end of the sealing portion 21 , the bulge or bump 23 having an axial si ze greater than the axial si ze of the main body 22 .

[0148] In detail , sealing portion 21 extends radially outwards , with respect to axis A. Main body 22 extends annularly about axis A and is attached to collar 20 . Bump 23 is attached to main body 22 and is arranged in a radially more external position than main body 22 relative to axis A. Sealing portion 16 is attached to an axial end portion of collar 20 and protrudes radially therefrom in a cantilevered manner, so as to de fine the aforementioned L-shape .

[0149] It is speci fied that with the wording "profile" or " semi-profile" it is intended a cross section of the relative part or component .

[0150] Preferably, bump 23 extends annularly in a continuous manner about axis A.

[0151] Conveniently, bump 23 has a substantially circular profile .

[0152] More speci fically, bump 23 defines an o-ring shaped body of sealing portion 21 .

[0153] Since bump 23 has an axial si ze greater than the axial si ze of main body 22 , bump 23 is configured to be compressed, in use and in assembled conditions of lid assembly 1 , between base plate 4 and collector 5 , while leaving main body 22 substantially uncompressed .

[0154] The Applicant has observed that such a configuration ensures a more ef fective sealing of inner compartment 3 , especially after an extended usage time . As it is known, during use of the battery cell pressure could build up within inner compartment 3 ; in such a case , collector 5 presses more and more towards base plate 4 and therefore onto sealing portion 21 . The Applicant has observed, by means of an extensive experimental campaign, that thanks to the peculiar geometry of first sealing member 13 , stresses concentrate on bump 23 , while main body 22 remains substantially unstressed and undeformed, thus resulting in an increase of ef ficacy of sealing and in a decrease of the risks of electrical contact between collector 5 and base plate 4 .

[0155] In addition, the presence of bump 23 according to the invention minimi zes risk that base plate 4 and collector 5 come into axial contact .

[0156] In light of the above , in the aforementioned assembled configuration of lid assembly 1 , the first sealing member 13 and the second sealing member 14 are pressed in contact with one another and optimally fill air gap 17 , as shown in Figure 3 .

[0157] In other words , thanks to their structural conformation, first sealing member 13 and the second sealing member 14 assume the deformed configuration shown in Figure 3 .

[0158] The Applicant has thus observed that the particular shape and conformation of first sealing member 13 and the second sealing member 14 ensures that first sealing member 13 and the second sealing member 14 remain pressed in contact against one another for any level of compressive force applied on lid assembly 1 during its assembling and in use during its functioning.

[0159] Hence, the fluid-tight sealing between inner compartment 3 and the outer environment is more reliable and improved.

[0160] The advantages of lid assembly 1 according to the present invention will be clear from the foregoing description .

[0161] In particular, thanks to the double seal configuration of sealing assembly 12, i.e. thanks to the presence of first sealing member 13 dedicated to fluid- tightly stop the electrolytic material and of second sealing member 14 dedicated to f luid-tightly stop the cooling fluid, the fluid-tight sealing properties of lid assembly 1 are significantly improved.

[0162] More in particular, the electrolytic material, i.e. a polar medium, is sealed by, and with, a nonpolar material (e.g. EPDM rubber) , whereas the cooling fluid, i.e. a nonpolar medium, is sealed by, and with, a polar material (e.g. NBR rubber or HNBR rubber) . Thanks to this configuration, the sealing properties of lid assembly 1 are furthermore significantly improved, especially compared to the known prior art solution whereby the polar electrolytic material is sealed with FKM or resin, which are polar materials. In fact, the Applicant has observed that when a polar medium is sealed by a nonpolar material, and vice-versa, the sealing properties are largely improved .

[0163] In other words , lid assembly 1 according to the present invention and including a sealing assembly 12 with dedicated sealing functions , allows to separate the outward and inward sealing functions , in order to ef fectively provide media separation and electro-chemical compatibility thereof .

[0164] Accordingly, the li fespan of sealing assembly 12 is increased .

[0165] In addition, the Applicant has observed that second sealing member 14 , when being made of NBR rubber or HNBR rubber, has an improved behavior in cold condition . This is particularly advantageous , given the fact that second sealing member 14 is lapped, in use , by the cooling fluid .

[0166] Clearly, changes may be made to lid assembly 1 as described herein without , however, departing from the scope of protection as defined in the accompanying claims .

Claims

CLAIMS1.- Lid assembly (1) for a prismatic battery cell having a casing (2) which internally defines an inner compartment (3) for housing electrodes and an electrolytic material and at least one opening (3a) for accessing the inner compartment (3) , the lid assembly (1) being configured to f luid-tightly close the inner compartment (3) and comprising:- a base plate (4) configured to close the opening (3a) of the inner compartment (3) ; a current collector (5) configured to be electrically connected to a respective electrode of the battery cell within the inner compartment (3) for collecting electrical energy therefrom and transferring it from the inner compartment (3) outwards;- a terminal member (6) electrically connected with the current collector (5) for receiving the electrical energy therefrom and configured to be electrically coupled with a connector of a consumer device which has to be powered by the battery cell; and- a sealing assembly (12) configured to define a fluid-tight seal between the inner compartment (3) and an outer environment external to the inner compartment (3) ; wherein the sealing assembly (12) comprises:- a first sealing member (13) interposed between thecurrent collector (5) and the base plate (4) for fluid- tightly preventing an outflow of said electrolytic material from the inner compartment (3) ; and- a second sealing member (14) interposed between the terminal member (6) and the base plate (4) for fluid- tightly preventing an inflow of an external fluid from the outer environment towards the inner compartment (3) .2.- Lid assembly (1) as claimed in claim 1, wherein the first sealing member (13) and the second sealing member (14) define two distinct and separate components with solution of continuity.3.- Lid assembly (1) as claimed in claim 2, wherein the first sealing member (13) and the second sealing member (14) are fixed to one another via a carrier member so that the sealing assembly (12) is defined by a single component including three pieces coupled to one another, the carrier member being preferably made of rigid thermoplastic material.4.- Lid assembly (1) as claimed in claim 2 or 3, and internally defining a first space (15) delimited between the base plate (4) and the current collector (5) and a second space (16) delimited between the terminal member (6) and the base plate (4) , wherein the first space (15) is engaged by the first sealing member (13) , so that the first sealing member(13) is pressed against the base plate (4) and the current collector (5) , and the second space (16) is engaged by the second sealing member (14) , so that the second sealing member (14) is pressed between the terminal member (6) and the base plate (5) ; wherein the first space (15) and the second space (16) are fluidically connected, thereby defining an air gap (17) within the lid assembly (1) ; and wherein the first sealing member (13) and the second sealing member (14) are pressed in contact against one another so as to f luid-tightly close the air gap (17) .5.- Lid assembly (1) as claimed in claim 1, wherein the first sealing member (13) and the second sealing member (14) are made in one single piece without solution of continuity, so as to define two joined sealing portions of the sealing assembly (12) , and so that the sealing assembly (12) comprises only one single piece without solution of continuity.6.- Lid assembly (1) as claimed in any one of the foregoing claims, wherein the first sealing member (13) comprises a nonpolar material at least at an outer surface thereof, so that such outer surface is completely defined by the nonpolar material.7.- Lid assembly (1) as claimed in claim 6, wherein the first sealing member (13) is made of EPDM rubber atleast at the outer surface thereof.8.- Lid assembly (1) as claimed in any one of the foregoing claims, wherein the second sealing member (14) comprises a polar material at least at an outer surface thereof, so that such outer surface is completely defined by the polar material.9.- Lid assembly (1) as claimed in claim 8, wherein the second sealing member (14) is made of NBR rubber or HNBR rubber at least at the outer surface thereof.10.- Lid assembly (1) as claimed in any one of the claims 1 to 5, wherein the first sealing member (13) is completely made of nonpolar material, preferably EPDM rubber, and the second sealing member (14) is completely made of polar material, preferably NBR rubber or HNBR rubber .11.- Lid assembly (1) as claimed in any one of the foregoing claims, wherein the first sealing member (13) is configured to be lapped by the electrolytic material and is configured to prevent the second sealing member (14) from being contacted by the electrolytic material, and wherein the second sealing member (14) is configured to be lapped by a cooling fluid for cooling the battery cell and is configured to prevent the first sealing member (13) from being contacted by the cooling fluid .12.- Lid assembly (1) as claimed in any one of the foregoing claims, and comprising a pin member (7) coupling mechanically, and connecting electrically, the terminal member (6) with the current collector (5) ; wherein the first sealing member (13) and the second sealing member (14) have an annular shape and define, each, a through hole engaged by the pin member (7) .13.- Lid assembly (1) as claimed in any one of the foregoing claims, wherein the second sealing member (14) has an annular shape about a central axis (A) thereof and has a semi-profile with a non-symmetrical cross-section, relatively to the axial direction.14.- Lid assembly (1) as claimed in claim 13, wherein the semi-profile of the second sealing member (14) has a lobed cross-section shaped so as to include a first lobe (18a) and a second lobe (18b) protruding from the first lobe (18a) , and wherein: the first lobe (18a) is arranged in a radially outer position with respect to the second lobe (18b) , relatively to the central axis (A) ; and / or the first lobe (18a) has a radial size larger than the radial size of the second lobe (18b) ; and / or the second lobe (18b) is pressed in contact against the first sealing member (13) ; and / or the first lobe (18a) is compressed between theterminal member (6) and the base plate (4) .15.- Lid assembly (1) as claimed in claim 13, wherein the semi-profile of the second sealing member (14) has a D-shaped cross-section with a perimeter (19) including a substantially straight section (19a) , which extends substantially parallel to the central axis (A) , and a curve section (19b) which joins the two ends of the straight section (19a) and faces the central axis (A) .16.- Lid assembly (1) as claimed in any one of the foregoing claims, wherein the first sealing member (13) has a central axis (A) , presents a substantially L-shaped semi-profile with respect to the central axis (A) , and comprises :- an axial collar (20) extending annularly about the central axis (A) ; and- a radial sealing portion (21) protruding from the collar (20) in a cantilevered manner; the sealing portion (21) including a main body (22) and a bulge or bump (23) extending from the main body (22) and defining a free end of the sealing portion (21) , the bulge or bump (23) having an axial size greater than the axial size of the main body (22) .17.- Lid assembly as claimed in claim 16, wherein: the sealing portion (21) extends radially outwards with respect to the central axis (A) , the main body (22)extends annularly about the central axis (A) and is attached to the collar (20) , the bulge or bump (23) is attached to the main body (22) and is arranged in a radially more external position than the main body (22) , relative to the central axis (A) ; and / or the bulge or bump (23) extends annularly about the central axis (A) and has a substantially circular profile, so as to define an o-ring shaped body of the sealing portion (21) .18.- Battery cell comprising:- a hollow casing (2) defining an inner compartment (3) for housing electrodes and an electrolytic material and having an opening (3a) ; a lid assembly (1) as claimed in any of the foregoing claims and arranged to close the opening (3a) for f luid-tightly closing the inner compartment (3) .