Lid assembly for a prismatic battery cell

Abstract

There is described a lid assembly (1) for a 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) comprises: a base plate (4) configured to close the opening (3a) of the inner compartment (3); a terminal group (50) configured to be electrically connected, at an inner side thereof, to a respective electrode within the inner compartment (3) for collecting electrical energy therefrom and configured to be electrically coupled, at an outer side thereof, with a connector of a device to be powered by the battery cell; an elastomeric sealing member (11) arranged between the base plate (4) and the terminal group (50) and configured to define a fluid-tight seal between the inner compartment (3) and an outer environment external to the inner compartment (3); the lid assembly (1) further comprises a spacer member (14) interposed between the base plate (4) and the terminal group (50) so as to avoid a direct contact between them, the spacer member (14) is made of a rigid and electrically insulating material.

Description

[0001] LID ASSEMBLY FOR A PRISMATIC BATTERY CELL

[0002] Cross-Reference to Related Applications

[0003] This Patent Application claims priority from Italian Patent Application No . 102024000018946 filed on August 12 , 2024 , the entire disclosure of which is incorporated herein by reference .

[0004] Technical Field

[0005] 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 .

[0006] Background Art

[0007] Battery cells are known, which are used as electrical energy accumulators .

[0008] 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 .

[0009] 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 .

[0010] Also , batteries which include a plurality of cells connected in series or in parallel are known, for example as used in the automotive industry .

[0011] 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 . 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 inner compartment also houses a separator material electrically interposed between the two electrodes .

[0015] Within the inner 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 inner 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 inner 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 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 current collector for receiving the electric energy therefrom, and which is configured to receive a connector of a device which has to be powered by the battery cell .

[0022] For each electrode , the terminal member and the current collector are usually coupled ( electrically and mechanically) with one another via a terminal pin or rivet , 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 current collector is arranged on a second internal side of the base plate , opposite the first side .

[0024] In light of the above , the terminal member, the terminal pin and the current collector define together a terminal group of the lid assembly . The current col lector defines a foot plate of the terminal group . The terminal group has a longitudinal axis , the terminal pin being usually coaxial with such axis .

[0025] The lid assembly may comprise two or more of such terminal groups .

[0026] A typical lid assembly also comprises a first insulator member for each terminal group, which is interposed between the relative terminal member and the base plate for electrically insulating the terminal member from the base plate .

[0027] A typical lid assembly further comprises a second insulator member for each terminal group, which is interposed between the relative current collector and the base plate for electrically insulating the current collector from the base plate .

[0028] The lid assembly further comprises a seal element for each electrode . The seal element is made of resilient ( elastomeric ) and electrically insulating material and serves the twofold function of : electrically insulating the terminal group ( and especially the terminal pin and the current collector ) from the base plate ; and fluid- tightly sealing the inner compartment of the casing from the outside environment .

[0029] To this end, the seal element is mechanically interposed between the respective current collector and terminal pin and the base plate , so that the current collector and the terminal pin are not arranged in direct contact with the base plate , but still being mutually coupled via the seal element itsel f .

[0030] During assembly of the battery cell , the various components mentioned above are axially stacked and compressed together , with respect to the longitudinal axis of the terminal group .

[0031] US2019189995A1 , EP2958160A1 , US 8841022B2 and US2022399620A1 di sclose examples o f lid assemblies of the type described above .

[0032] It is fundamental that the electrical insulation between the base plate and the terminal group is correctly maintained throughout the operational li fespan of the lid assembly, and therefore of the battery cell .

[0033] It is known that the battery cell , and therefore the lid assembly coupled to this latter, may be subj ected, during operation, to rather high loads and stresses along directions orthogonal to the longitudinal axis of the terminal group ( i . e . radial direction) .

[0034] Such " lateral" loads maybe due to various causes , such as thermal expansions , pressure build-ups within the inner compartments , and abrupt and strong accelerations ( for example in certain performance applications , such as competition cars , or due to a sudden crash) .

[0035] The lateral loads and stresses may cause a displacement of the components along the radial direction .

[0036] Normally, large part of such displacement is "absorbed" by the seal element .

[0037] However, being the seal element elastomeric, it allows ( and cannot avoid) a relative displacement between the base plate and the terminal group .

[0038] In some cases , especially in case of high lateral loads and stresses , such relative displacement may be too high, and therefore detrimental to the electric insulation between the base plate and the terminal group, since an electric bridge may establish between these latter .

[0039] Moreover, the lateral loads and stresses may exceed the deformation recovery capabilities of the seal element , thereby further increasing the risk of an electric bridge between the terminal group and the base plate .

[0040] In some solutions , the various components mentioned above , and especially the base plate , the terminal member, the current collector, as well as the first insulator member and the second insulator member, are provided with external surface features ( such as ribs and corresponding grooves which are complementary in shape with one another ) , which act as lateral abutment and help to withstand the lateral loads .

[0041] However, the manufacturing of such external surface features may be complicated, as it requires a longer production timespan and involves higher costs , especially for rigid components such as the base plate , which in some cases may be made of stainless steel .

[0042] Therefore , the need is felt to improve the overall resistance of the lid assembly against the lateral loads and stresses for guaranteeing and improving the electrical insulation between the base plate and the terminal group, while at the same time simpli fying the architecture of the lid assembly and the manufacture thereof .

[0043] Disclosure of Invention

[0044] It is therefore an obj ect of the present invention to provide a lid assembly which is designed to overcome at least one of the above-mentioned drawbacks in a straightforward and low-cost manner .

[0045] 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 .

[0046] Brief Description of the Drawings

[0047] Non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings , in which :

[0048] 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;

[0049] Figure 2 is a larger-scale sectioned view, with parts removed for clarity, of a terminal area of the lid assembly of Figure 1 , according to a first preferred embodiment of the present invention;

[0050] Figure 3 is a larger-scale sectioned view, with parts removed for clarity, of a terminal area of the lid assembly of Figure 1 , according to a second preferred embodiment of the present invention;

[0051] Figure 4 is a larger-scale sectioned view, with parts removed for clarity, of a terminal area of the lid assembly of Figure 1 , according to a third preferred embodiment of the present invention;

[0052] Figure 5 is a sectioned view, with parts removed for clarity, of a spacer member of the lid assembly of Figure 1 , according to a preferred embodiment of the invention;

[0053] Figure 6 is a sectioned view, with parts removed for clarity, of a spacer member of the lid assembly of Figure 1 , according to a further preferred embodiment of the invention;

[0054] Figure 7 is a larger-scale sectioned view, with parts removed for clarity, of a terminal area of the lid assembly of Figure 1 , according to a fourth preferred embodiment of the present invention .

[0055] Best Mode for Carrying out the Invention

[0056] With reference to Figure 1 , number 1 indicates as a whole a lid assembly for a battery cell .

[0057] In particular, the battery cell is of the prismatic type and has a hollow prismatic casing 2 which internally defines an inner compartment 3 and which presents an opening 3a to access inner compartment 3 . According to the embodiment shown, casing 2 has a parallelepiped shape . Alternatively, casing 2 may have any prismatic shape , such as cubic, triangular-based, etc .

[0058] In one embodiment , casing 2 could be cylindrical . In such a case , lid assembly 1 has a round configuration .

[0059] The present invention will refer to a prismatic battery cell , without however losing generality .

[0060] 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 .

[0061] 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) .

[0062] The electrolytic material may be liquid or gelatinous .

[0063] The electrodes and the separator material are inserted into inner compartment 3 from opening 3a .

[0064] 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 .

[0065] Hence , the battery cell comprises casing 2 , with the electrodes , the separator and the electrolytic solution, and lid assembly 1 .

[0066] The battery cell is preferably part of a battery module including a plurality of battery cells electrically connected to one another in parallel .

[0067] Casing 2 may comprise a further opening 3a opposite to the aforementioned opening 3a, as indicated in Figure 1 . A further lid assembly 1 is to be coupled with casing 2 so as to f luid-tightly close the further opening 3a .

[0068] In the following, reference will be made to a single lid assembly 1 , for the sake of brevity .

[0069] As visible in Figure 1 , lid assembly 1 comprises a base plate 4 , made of metallic material , such as aluminum or stainless steel , configured to be coupled to casing 2 at opening 3a for closing opening 3a of inner compartment 3 , namely arranged to match the shape of , and engage , opening 3a for closing inner compartment 3 .

[0070] Lid assembly 1 further comprises a terminal group 50 configured to be electrically connected, at an inner side 5 thereof , to a respective electrode within inner compartment 3 for collecting electrical energy therefrom and configured to be electrically coupled, at an outer side 6 thereof , with a connector of a device (not shown) to be powered by the battery cell .

[0071] In particular, terminal group 50 has a longitudinal axis A and includes : a current collector 5 which defines the aforementioned inner side of terminal group 50 and is configured to be electrically connected to the respective electrode ; a terminal member 6 which defines the aforementioned outer side of terminal group 50 and is configured to be electrically coupled with the aforementioned connector ; and a terminal pin 7 which is axially interposed between current collector 5 and terminal member 6 and electrically connects these latter to one another . More in particular, terminal pin 7 is welded, at one axial side thereof , to terminal member 6 and, at the opposite axial side thereof , to current collector 5 .

[0072] Preferably, terminal pin 7 is substantially cylindrical and is arranged coaxially to axis A.

[0073] Terminal group 50 extends along the axial direction from inner compartment 3 to an outer environment external to inner compartment 3 .

[0074] In detail , terminal member 6 is arranged at an outer side of the base plate 4 ( i . e . the side facing the outer environment ) , so as to be connected to the connector, and the collector 5 is arranged at an inner side of the base plate 4 ( i . e . the side facing inner compartment 3 ) , so as to be connected with the respective electrode .

[0075] Opportunely, base plate 4 has a through hole 4a, which is engaged by terminal pin 7 .

[0076] In light of the above , current collector 5 and terminal member 6 are arranged on opposite sides of base plate 4 , with respect to the axial direction .

[0077] Lid assembly 1 may comprise two or more terminal groups 50 . In the following, only one terminal group 50 will be considered, for the sake of brevity .

[0078] Lid assembly 1 further comprises : a first insulator member 8 axially interposed between terminal member 6 and base plate 4 for electrically insulating terminal member 6 from base plate 4 ; and

[0079] - a second insulator member 10 axially interposed between current collector 5 and base plate 4 for electrically insulating current collector 5 from base plate 4 . Opportunely, first insulator member 8 and second insulator member 10 are made of an electrically insulating material , such as PPS ( Polyphenylene sul fide ) or PP ( Polypropylene ) .

[0080] Lid assembly 1 further comprises an elastomeric sealing member 11 arranged between base plate 4 and terminal group 50 and configured to define a fluid-tight seal between inner compartment 3 and the outer environment external to inner compartment 3 .

[0081] Conveniently, sealing member 11 has an annular shape and is arranged around terminal pin 7 , coaxially with axis A.

[0082] In detail , sealing member 11 is defined by an o-ring and is interposed axially between base plate 4 and current collector 5 .

[0083] Moreover, sealing member 11 is interposed radially between second insulator member 10 and terminal pin 7 .

[0084] Sealing member 11 is configured for preventing an outflow of electrolytic material from inner compartment 3 outwards , as well as the entrance of external substances ( dirt , water, etc ) into inner compartment 3 .

[0085] Conveniently, lid assembly 1 further comprises :

[0086] - a stop frame (not shown) made of an electrically insulating material ( such as rigid plastic ) , known per se and not described in detail ;

[0087] - a pour opening 13a obtained in base plate 4 through which the electrolytic material is to be inserted; and

[0088] - a cap 13b for closing pour opening 13a .

[0089] According to an important aspect of the present invention, lid assembly 1 further comprises a spacer member 14 interposed between base plate 4 and terminal group 50 so as to avoid a direct contact between them . Spacer member 14 is made of a rigid and electrically insulating material .

[0090] In particular, spacer member 14 is made of a rigid and non-elastically deformable material .

[0091] Preferably, spacer member 14 is made of a rigid and non-elastomeric material .

[0092] Preferably, spacer member 14 is made of polypropylene .

[0093] According to a further important aspect of the invention, spacer member 14 is interposed between terminal group 50 and base plate 4 along a radial direction orthogonal to axis A and, therefore , to the axial direction .

[0094] More precisely, spacer member 14 is interposed between terminal pin 7 and base plate 4 along the radial direction .

[0095] This configuration is better visible in Figure 2 : base plate 4 rests on spacer member 14 and spacer member 14 rests on terminal pin 7 , relatively to the radial direction .

[0096] According to the non-limiting preferred embodiment shown, spacer member 14 has an annular configuration, and is preferably def ined by a spacing ring or annular washer .

[0097] Preferably, spacer member 14 is coaxial to axis A.

[0098] Conveniently, spacer member 14 is fitted on an external surface 7a of terminal pin 7 .

[0099] In greater detail , spacer member 14 includes an inner radial surface 14a and an outer radial surface 14b .

[0100] Inner radial surface 14a is f itted on external surface 7a, while base plate 4 radially rests against outer radial surface 14b .

[0101] More precisely, spacer member 14 engages ( together with terminal pin 7 ) through hole 4a of base plate 4 . In more detail , the lateral wall which delimits through hole 4a rests in abutment against outer radial surface 14b .

[0102] Preferably, also sealing member 11 has an annular configuration ( about axis A) and is fitted radially on spacer member 14 .

[0103] More in detail , sealing member 11 is fitted on outer radial surface 14b .

[0104] In light of the above , sealing member 11 is arranged radially more external than spacer member 14 .

[0105] More precisely, as visible in particular in Figure 2 , lid assembly 1 internally defines an L-shaped cavity or space 15 which is delimited, in the radial direction, by terminal pin 7 on one side ( radially internal side ) and by base plate 4 , first insulating member 8 and second insulating member 10 on the other side ( radially external side ) .

[0106] The L-shaped cavity 15 is further delimited, in the axial direction, by terminal member 6 on one side ( axially external side ) and by current collector 5 on the other side ( axially internal side ) .

[0107] Spacer member 14 and sealing member 11 occupy the L- shaped cavity 15 : in particular, spacer member 14 occupies the axial portion of the L-shaped cavity 15 , whereas sealing member 11 occupies the radial portion of the L- shaped cavity 15 , which is arranged in a radially more external position than the axial portion, with respect to axis A.

[0108] Thanks to the presence of spacer member 14 and to its positioning relatively to the other components , and especially to base plate 4 , the structural stability and electric insulation properties of lid assembly 1 are signi ficantly improved .

[0109] In fact , spacer member 14 , being made in a rigid and electrically insulating material , defines , at least for base plate 4 , a relief stop for relieving loads or stresses exerted, in use , on lid assembly 1 in a direction parallel to said radial direction .

[0110] More speci fically, the lateral loads and stresses mentioned above in the introductory portion of the description, are discharged onto space member 14 . Being rigid, spacer member 14 does not incur in any substantial deformation . Hence , the relative positions between the various components of lid assembly, and most importantly between base plate 4 and terminal group 50 , remain substantially unchanged .

[0111] Therefore , base plate 4 is prevented from approaching terminal group 50 under lateral loads and stresses exerted on base plate 4 , thereby signi ficantly reducing the risk of an electric bridge between these components .

[0112] Moreover, this technical ef fect is reached without the need for any complicated surface feature on any component of lid assembly 1 . Therefore , the architecture of lid assembly 1 is simpli fied, and the manufacture thereof is more cost and time ef fective .

[0113] Expediently, spacer member 14 is interposed between terminal member 6 and current collector 5 along the axial direction .

[0114] More in particular, spacer member 14 includes an inner axial surface 14c and an outer axial surface 14d .

[0115] According to a first preferred embodiment of the invention, shown in Figure 2 , spacer member 14 axially rests on current collector 5 and axially extends from the current collector up to terminal member 6 .

[0116] In detail , inner axial surface 14c axially rests on current collector 5 , while terminal member 6 axially rests on outer axial surface 14d .

[0117] Thanks to the above configuration, spacer member 14 defines a relief stop also for any possible axial loads or stresses that may be exerted on lid assembly 1 .

[0118] In this way, the structural stabil ity of lid assembly 1 and the electrical insulation between base plate 4 and terminal group 50 are further improved .

[0119] Figure 3 shows a second preferred embodiment of l id assembly 1 according to the present invention .

[0120] In particular, lid assembly 1 according to such second embodiment di f fers from the lid assembly 1 according to the first embodiment in that :

[0121] - first insulator member 8 extends along the radial direction and radially abuts against external surface 7a of terminal pin 7 ; and

[0122] - spacer member 14 axially rests on current collector 5 and axially extends from current collector 5 to first insulator member 8 .

[0123] In other words , while inner axial surface 14c axially rests on current collector 5 as in the first embodiment , outer axial surface 14d axially abuts against ( an axial surface of ) first insulator member 8 .

[0124] Thanks to this alternative configuration, the overall structural ef ficiency of lid assembly 1 is improved . Moreover, the so-called "creepage" distance between base plate 4 and terminal member 6 or terminal pin 7 is increased . This results in an improved behavior of lid assembly 1 under high voltage conditions .

[0125] According to an alternative embodiment shown in Figure 7 , spacer member 14 may comprise , at its outer axial surface 14d, a first radial shoulder 22 .

[0126] That is , outer axial surface 14d may include a step which defines such first radial shoulder 22 .

[0127] Accordingly, first insulator member 8 may include a corresponding second radial shoulder 23 which abuts , in the radial direction, against first radial shoulder 22 .

[0128] In particular, second radial shoulder 23 is complementary in shape with first radial shoulder 22 .

[0129] Such configuration further enhances the overall structural ef ficiency of lid assembly 1 and further increases the aforementioned creepage distance between base plate 4 and terminal member 6 or terminal pin 7 .

[0130] Moreover, the radial shoulders 22 and 23 provide for a further aid in withstanding the lateral loads and stresses .

[0131] As visible in the appended Figures , spacer member 14 advantageously has a cross-section which presents a symmetrical shape relative to a central symmetry line thereof parallel to the axial direction .

[0132] In detail , the semi-profile of the cross-section ( relatively to axis A) presents such symmetrical shape .

[0133] In the example shown, the semi-profile has a substantially rectangular shape .

[0134] The symmetrical shape of spacer member 14 facilitates easy assembly and ensures a correct positioning to prevent assembly errors .

[0135] According to a preferred embodiment of the invention shown in particular in Figure 5 , the semi-profile of the cross-section of spacer member 14 presents rounded or chamfered edges 16 .

[0136] According to an alternative embodiment shown in particular in Figure 6 , the semi-profile of the crosssection of spacer member 14 presents inclined surfaces 17 at the edges 16 thereof .

[0137] In detail , surfaces 17 are inclined with respect to both radial surfaces 14a, 14b and axial surfaces 14c, 14d .

[0138] The presence of rounded edges 16 or of inclined surfaces 17 helps to minimi ze the risk of damages to seal member 11 during assembly of lid assembly 1 , whereby all the components are stacked and compressed together .

[0139] Therefore , a nominal fluid-tight sealing can be ensured, and the li fespan of lid assembly 1 is increased .

[0140] Figure 4 shows a third preferred embodiment of lid assembly 1 according to the present invention .

[0141] In particular, lid assembly 1 according to such third embodiment di f fers from the lid assembly 1 described above according to the first embodiment for the features described hereinafter .

[0142] In detail , lid assembly 1 comprises a sealing assembly 18 configured to define a fluid-tight seal between inner compartment 3 and the outer environment .

[0143] Such sealing assembly 18 comprises :

[0144] - sealing member 11 , which as said is configured for f luid-tightly preventing an outflow of said electrolytic material from inner compartment 3 towards the outer environment ; and

[0145] - a further elastomeric sealing member 21 configured for f luid-tightly preventing an inflow of an external fluid from the outer environment towards inner compartment 3 .

[0146] Advantageously, according to this third embodiment , sealing member 11 comprises a nonpolar material at least at an outer surface thereof , so that such outer surface is completely defined by the nonpolar material , and further sealing member 21 comprises a polar material at least at an outer surface thereof , so that such outer surface is completely defined by the polar material .

[0147] According to such third embodiment of the present invention, sealing member 11 f luid-tightly seals the L- shaped cavity 15 from inner compartment 3 , and further sealing member 21 f luid-tightly seals the L-shaped cavity 15 from the outer environment .

[0148] The aforementioned configuration according to the third embodiment is particularly advantageous in the case in which the battery cell is configured to be immersed, in use , in a cooling fluid configured for cooling the battery cell during the operation thereof .

[0149] In detail , the battery cell is preferably part of a battery module (not shown) including a plurality of battery cells connected to one another in parallel . The module has an external housing (not shown) 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 .

[0150] 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.

[0151] Thanks to the double seal configuration of sealing assembly 18, i.e. thanks to the presence of sealing member 11 dedicated to f luid-tightly stop the electrolytic material and of further sealing member 21 dedicated to f luid-tightly stop the cooling fluid, the fluid-tight sealing properties of lid assembly 1 are significantly improved .

[0152] In fact, 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.

[0153] 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.

[0154] 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) .

[0155] Thanks to this configuration, the sealing properties of lid assembly 1 are even more significantly improved, especially compared to the known solutions whereby the polar electrolytic material is sealed with polar materials .

[0156] In fact, when a polar material interacts with a nonpolar material, their contact behavior is improved because, chemically, like dissolves like.

[0157] 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. In other words , lid assembly 1 according to the present invention and including a sealing assembly 18 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 .

[0158] Accordingly, the li fespan of sealing assembly 18 , and therefore of lid assembly 1 , is increased .

[0159] The advantages o f lid assembly 1 according to the present invention will be clear from the foregoing description .

[0160] In particular, thanks to the presence of spacer member 14 and to its positioning relatively to the other components , and especially to base plate 4 , the structural stability and electric insulation properties of lid assembly 1 are signi ficantly improved . In fact , lateral loads or stresses exerted, in use , at least on base plate 4 in the radial direction are discharged to , relieved on or transmitted to space member 14 . Being rigid, spacer member 14 does not incur in any ( elastic ) deformation . Hence , the relative positions between the various components of lid assembly, and most importantly between base plate 4 and terminal group 50 , remain substantially unchanged . Hence , base plate 4 is prevented from approaching terminal group 50 under lateral loads and stresses exerted on base plate 4 , thereby signi ficantly reducing the risk of an electric bridge between these components . Moreover, this technical ef fect is reached without the need for any complicated surface feature on any component of lid assembly 1 . Therefore , the architecture of lid assembly 1 is simpli fied, and the manufacture thereof is more cost and time ef fective .

[0161] 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 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 terminal group (50) configured to be electrically connected, at an inner side thereof, to a respective electrode within the inner compartment (3) for collecting electrical energy therefrom and configured to be electrically coupled, at an outer side thereof, with a connector of a device to be powered by the battery cell; an elastomeric sealing member (11) arranged between the base plate (4) and the terminal group (50) and configured to define a fluid-tight seal between the inner compartment (3) and an outer environment external to the inner compartment (3) ; wherein the lid assembly (1) further comprises a spacer member (14) interposed between the base plate (4) and the terminal group (50) so as to avoid a direct contact between them; wherein the spacer member (14) is made of a rigid and electrically insulating material; wherein the terminal group (50) has a longitudinal axis (A) and extends along the axial direction from the inner compartment (3) to the outer environment; wherein the terminal group (50) includes:- a current collector (5) which defines said inner side of the terminal group (50) and is configured to be electrically connected to said respective electrode;- a terminal member (6) which defines said outer side of the terminal group (50) and is configured to be electrically coupled with said connector; and- a terminal pin (7) which is axially interposed between the current collector (5) and the terminal member (6) and electrically connects the current collector (5) with the terminal member (6) ; wherein the current collector (5) and the terminal member (6) are arranged on opposite sides of the base plate (4) , with respect to the axial direction; wherein the spacer member (14) is interposed between the terminal pin (7) and the base plate (4) along a radial direction orthogonal to the longitudinal axis (A) ; and wherein the spacer member (14) has an annular configuration and is fitted on an external surface (7a) of the terminal pin (7) .2.- Lid assembly as claimed in claim 1, wherein the spacer member (14) is made of a rigid and non-elastomeric material .3.- Lid assembly as claimed in claim 1 or 2, wherein the spacer member (14) is interposed between the terminal member (6) and the current collector (5) along said axial direction; wherein the spacer member (14) axially rests on the current collector (5) and axially extends from the current collector (5) to the terminal member (6) .4.- Lid assembly as claimed in any one of the foregoing claims, and comprising:- a first insulator member (8) axially interposed between the terminal member (6) and the base plate (4) for electrically insulating the terminal member (6) from the base plate (4) ; and- a second insulator member (10) axially interposed between the current collector (5) and the base plate (4) for electrically insulating the current collector (5) from the base plate (4) ; wherein the spacer member (14) is interposed between the terminal member (6) and the current collector (5) along said axial direction; wherein the first insulator member (8) extends along said radial direction and radially abuts against an external surface (7a) of the terminal pin (7) ; and wherein the spacer member (14) axially rests on the current collector (5) and axially extends from the current collector (5) to the first insulator member (8) .5.- Lid assembly as claimed in any one of the foregoing claims, wherein the sealing member (11) has an annular configuration and is fitted radially on the spacer member (14) , so that the sealing member (11) is arranged radially more external than the spacer member (14) .6.- Lid assembly as claimed in any one of the foregoing claims, wherein the spacer member (14) defines, at least for the base plate (4) , a relief stop for relieving loads or stresses exerted, in use, on the lid assembly (1) in a direction parallel to said radial direction .7.- Lid assembly as claimed in any one of the foregoing claims, wherein the terminal group (50) has a longitudinal axis (A) and extends along the axialdirection from the inner compartment (3) to the outer environment ; and wherein the spacer member (14) has a crosssection which presents a symmetrical shape relative to a central symmetry line thereof parallel to the axial direction .8.- Lid assembly as claimed in any one of the foregoing claims, wherein the spacer member (10) has a cross-section defining a profile which presents rounded or chamfered edges (16) , or which presents inclined surfaces (17) at the edges (16) thereof.9.- Lid assembly as claimed in any one of the foregoing claims, and comprising a sealing assembly (18) configured to define a fluid-tight seal between the inner compartment (3) and the outer environment; wherein the sealing assembly (18) comprises:- said sealing member (11) configured for fluid- tightly preventing an outflow of said electrolytic material from the inner compartment (3) towards the outer environment ; a further elastomeric sealing member (21) configured for f luid-tightly preventing an inflow of an external fluid from the outer environment towards the inner compartment (3) ; wherein the sealing member (11) comprises a nonpolar material at least at an outer surface thereof, so that such outer surface is completely defined by the nonpolar material ; wherein the further sealing member (21) comprises a polar material at least at an outer surface thereof, so that such outer surface is completely defined by the polarmaterial ; wherein the lid assembly (1) internally defines an inner cavity (15) engaged by the spacer member (14) ; wherein the sealing member (11) f luid-tightly seals the inner cavity (15) from the inner compartment (3) , and wherein the further sealing member (21) f luid-tightly seals the inner cavity (15) from the outer environment.10.- Lid assembly as claimed in any one of the foregoing claims, wherein the spacer member (14) is made of polypropylene.

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