Battery pack provided with an improved thermal barrier device between the battery cells and such thermal barrier device

Abstract

There is described an electrical energy storage device (1) comprising a casing (2), at least two electrical energy storage cells (3) enclosed within the casing (2) and arranged adjacent to one another, and at least one thermal barrier device (7) interposed and stacked between the storage cells (3) in a thickness direction (T) thereof and configured to thermally insulate the adjacent storage cells (3), the thermal barrier device (7) has a mat-like configuration and includes two opposite lateral surfaces (7a, 7b) separated by a perimetral wall (8) defining the thickness of the thermal barrier device (7), the thermal barrier device (7) comprises a sealing member (10) extending along at least part of the perimetral wall (8) and arranged in abutment against the casing (2) so as to seal in a fluid- tight manner the adjacent storage cells (3) from one another.

Description

[0001] "BATTERY PACK PROVIDED WITH AN IMPROVED THERMAL BARRIER

[0002] DEVICE BETWEEN THE BATTERY CELLS AND SUCH THERMAL

[0003] BARRIER DEVICE"

[0004] Technical Field

[0005] The present invention relates to an electrical energy storage device in particular a battery pack having a housing and a plurality of battery cells enclosed in the housing and preferably designed for the use in a fullelectric or hybrid vehicle .

[0006] The present invention further relates to a thermal barrier device configured to be interposed between two adj acent battery cells of an electrical energy storage device , in particular a battery pack preferably designed for the use in a full-electric or hybrid vehicle .

[0007] Background Art

[0008] Battery cells are known, which are used as electrical energy accumulators .

[0009] 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 .

[0010] 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 , smart bands , etc .

[0011] Also , battery packs which include a plurality o f battery cells connected in series or in parallel are known, for example as used in the automotive industry .

[0012] The present invention will refer to a battery pack for the use in a hybrid or full-electric vehicle , for example an electric car, without however loss of generality .

[0013] A single battery cell typically comprises a hollow casing, for example in the shape of a hollow parallelepiped and usually made of metallic material , generally open on at least one side ( for example on the top ) and a lid for closing the casing .

[0014] The casing internally defines an inner compartment of the cell and houses the cell electrodes ( cathode and anode ) , which are provided for example in the form of sheets , and a separator material electrically interposed between the electrodes .

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

[0016] The lid is coupled to the housing at an opening thereof for closing the inner compartment in a fluid- tight manner, thereby maintaining electrodes and separator in place and preventing the outflow of the electrolytic material .

[0017] Typically, the lid carries the electrical poles , i . e . the positive and negative terminals , of the respective battery cells .

[0018] A typical battery pack essentially comprises a housing and a plurality of such battery cells enclosed within the housing .

[0019] Usually, the battery pack further comprises a number of thermal barrier assemblies , each one interposed between two adj acent battery cells .

[0020] More speci fically, between each pair of adj acent battery cells one thermal barrier assembly is arranged so that the thermal barrier assembly is interposed between the facing lateral walls of such adj acent battery cells .

[0021] The thermal barrier assembly is configured to thermally insulate each battery cell from the adj acent ones .

[0022] As it is known, the unlikely event of so called "thermal runway" may occur for one or more battery cells of the battery pack .

[0023] During such a thermal runway event , gas developed within the battery cell may abruptly outflow from the casing thereof , and in particular from a safety venting port usually obtained at the lid thereof .

[0024] In some cases , the thermal runway event may lead to a development of a fire within the battery pack housing, which may be detrimental for the other battery cells .

[0025] Even without an ignition, a thermal runway event occurring in one battery cell may af fect the other battery cells of the same battery pack .

[0026] The Applicant has observed how the energy storage devices , i . e . the battery packs , of the known type are still open to further improvement , in particular as per increasing their li fespan .

[0027] Disclosure of Invention

[0028] It is therefore an obj ect of the present invention to provide an electrical energy storage device which is designed to overcome at least one of the above-mentioned drawbacks in a straightforward and low-cost manner .

[0029] This obj ect is achieved by an electrical energy storage device as claimed in the appended independent claim 1 .

[0030] It is a further obj ect of the present invention to provide a thermal barrier device for an electrical energy storage device which is designed to overcome at least one of the above-mentioned drawbacks in a straightforward and low- co st manner .

[0031] This obj ect is achieved by a thermal barrier device as claimed in the appended independent claim 20 .

[0032] Preferred embodiments of the present invention are laid down in the appended dependent claims .

[0033] Brief Description of the Drawings

[0034] A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings , in which :

[0035] Figure 1 is an exploded perspective view, with parts removed for clarity, of a battery pack according to the present invention;

[0036] Figure 2 is a larger-scale , partially sectioned side view, with parts removed for clarity, of the battery pack of Figure 1 in assembled configuration;

[0037] Figure 3a is a cross-section, with parts removed for clarity, of a thermal barrier device for the battery pack according to a first embodiment of the present invention;

[0038] Figure 3b is a cross-section, with parts removed for clarity, of a thermal barrier device for the battery pack according to a second embodiment of the present invention;

[0039] Figure 3c is a cross-section, with parts removed for clarity, of a thermal barrier device for the battery pack according to a third embodiment of the present invention;

[0040] Figure 3d is a cross-section, with parts removed for clarity, of a thermal barrier device for the battery pack according to a fourth embodiment of the present invention;

[0041] Figure 4a is a cross-section, with parts removed for clarity, of a thermal barrier device for the battery pack according to a fi fth embodiment of the present invention;

[0042] Figure 4b is a cross-section, with parts removed for clarity, of a thermal barrier device for the battery pack according to a sixth embodiment of the present invention .

[0043] Best Mode for Carrying Out the Invention

[0044] With reference to Figure 1 , number 1 indicates as a whole an electrical energy storage device , in particular a battery pack, to which the present description will refer without loss of generality .

[0045] Battery pack 1 is preferably destined for the use in a vehicle , in particular a full-electric or hybrid vehicle , such as a car, a van, or the like , to which the present description will refer without loss of generality . Battery pack 1 includes a casing (or outer casing) 2 and at least two electrical energy storage cells 3, in particular battery cells, arranged within casing 2, and in particular enclosed in casing 2 and arranged adjacent to one another.

[0046] In detail, battery pack 1 comprises a plurality of battery cells 3, i.e. more than two battery cells 3 which are arranged within casing 2 adjacent to one another along a thickness direction T of the battery cells 3.

[0047] It is specified that with the expression "thickness direction" it is intended, in the present disclosure, a direction along the thickness of each battery cells 3, i.e. along the smallest dimension of the battery cell 3, the other two dimensions being the length and the height.

[0048] Hence, in the present disclosure "thickness" it is to be intended with the "width" of each battery cell 3.

[0049] Therefore, the "thickness direction" is a direction along which the width of the battery cells 3 develops.

[0050] Thickness direction T is shown in Figures 1 and 2.

[0051] Each battery cell 3 is of the known type and includes a housing which internally defines a compartment containing electrodes (cathode and anode) and a separator. The electrodes and the separator are immersed in an electrolytic solution.

[0052] In the preferred embodiment shown, each battery cells 3 is a prismatic battery cell, and preferably a rectangular-based prismatic battery cell.

[0053] Hence, each battery cell 3 has two opposite side walls 3a which have an area larger than the area of the other walls of the battery cell 3.

[0054] Moreover, the thickness direction T is to be intended as the direction along which the small side of each prismatic battery cell 3 develops.

[0055] Each battery cell 3 includes two electrical poles 4, i.e. the positive and negative terminals. In particular, each battery cell 3 has a lid 5 coupled to the respective housing at an opening thereof for closing the inner compartment in a fluid-tight manner, thereby maintaining electrodes and separator in place and preventing the outflow of the electrolytic material .

[0056] More in particular, electrical poles 4 are carried by lid 5 .

[0057] Each battery cell 3 further includes a safety venting port 6 , which is defined by a through hole obtained in lid 5 and is closed and sealed, during normal operation of the battery cell 3 , by a thin membrane , such as an aluminum foil .

[0058] The membrane defines a rupturable element which during a so-called thermal runway event ruptures thereby allowing the gas to outflow from the casing of battery cell 3 , according to a manner known and not described in detail .

[0059] Lid 5 is fixedly coupled to the casing of the battery cell 3 , and preferably is welded thereto .

[0060] In light of the above , each battery cell 3 has an operative wall , which in this embodiment is defined by lid 5 . Such operative wall ( i . e . lid 5 ) carries the respective electrical poles 4 . Moreover, the respective venting port 6 is obtained on such operative wall .

[0061] According to an alternative embodiment not shown, electrical poles 4 may be arranged on a wall of battery cell 3 other than operative wall 5 .

[0062] As visible in Figures 1 and 2 , battery cells are arranged within casing 2 so that their operative walls , i . e . their lids 5 , face a first internal wall 2a of casing 2 .

[0063] In use , operative wall 5 defines an upper wall of each battery cell 3 and first internal wall 2a defines an upper internal wall of casing 2 .

[0064] As shown in Figures 1 and 2 , battery pack 1 comprises a plurality of thermal barrier devices 7 , each interposed and stacked between a pair of adj acent battery cells 3 , with respect to thickness direction T , so that the adj acent battery cells 3 are spaced apart from one another by a respective thermal barrier device 4 in the thickness direction T .

[0065] In other words , each thermal barrier device 7 is clamped between two adj acent battery cells 3 .

[0066] Reference will be made in the following to a single pair of battery cells 3 adj acent to one another and to a single thermal barrier device 7 stacked between them . However, the structural and functional features disclosed hereinafter are equally applicable to each pair of adj acent battery cells 3 and to each thermal barrier device 7 .

[0067] Thermal barrier device 7 is configured to thermally insulate the two adj acent battery cells 3 .

[0068] In detail , as vi sible in Figure 3a, thermal barrier device 7 has a mat-like configuration and includes two opposite lateral surfaces 7a, 7b separated by a perimetral wall 8 defining the thickness of the thermal barrier device 7 .

[0069] In greater detail , each thermal barrier device 7 is arranged so that thickness direction T is also a thickness direction for thermal barrier devices 7 .

[0070] Perimetral wall 8 has a first portion or upper portion 8a facing first internal wall 2a, a second portion or lower portion 8b facing a second internal wall (not shown) of casing 2 which is opposite to first internal wall 2a, and a third portion or lateral portion 8c connecting first portion 8a and second portion 8b . Third portion 8c faces the lateral internal walls (not shown) of casing 2 which connect first internal wall 2a with the second internal wall .

[0071] In use , the second internal wall defines a lower wall of casing 2 .

[0072] Thermal barrier device 7 is interposed between two facing side walls 3a of the adj acent battery cells 3 so that each of the lateral surfaces 7a, 7b abuts against the side wall 3a of one respective battery cell 3 .

[0073] In other words , one lateral surface 7a abuts against the side wall 3a of a first battery cell 3 of the two adj acent battery cells 3 , whereas the other lateral surface 7b abuts against the side wall 3a of a second battery cell 3 of the two adj acent battery cells 3 .

[0074] Conveniently, each lateral surface 7a, 7b has an area at least equal to the area of the respective side wall 3a .

[0075] In this way, the thermal insulation between the adj acent battery cells 3 is ef fectively ensured .

[0076] According to an important aspect of the present invention, thermal barrier device 7 comprises a sealing member 10 extending along at least part of perimetral wall 8 and arranged in abutment against casing 2 so as to seal in a fluid-tight manner the adj acent battery cells 3 from one another .

[0077] More speci fically, thermal barrier device 7 defines two adj acent compartments 11 ( Figure 2 ) within casing 2 , each compartment 11 housing one respective battery cell 3 .

[0078] Advantageously, each compartment 11 is f luid-tightly sealed from the adj acent compartment 11 by means of sealing member 10 .

[0079] Conveniently, sealing member 10 extends along the entire aforementioned first portion or upper portion 8a and is arranged in abutment against first internal wall 2a, so as to seal in a fluid-tight manner adj acent venting ports 6 from one another, i . e . the venting ports 6 of the adj acent battery cells 3 .

[0080] It is speci fied that with the expression " fluid- tight" it is intended, in the present description and in the appended claims , that the sealing member 10 define an ef fective sealing barrier against fluids ( gases , liquids ) and also against solid particles .

[0081] According to one embodiment of the present invention, sealing member 10 extends also along the entire aforementioned second portion or lower portion 8b and is arranged in abutment against the second internal wall of casing 2 (not shown) .

[0082] According to one embodiment not shown, sealing member 10 may extend also along the entire third portion 3c . In other words , sealing member 10 may extend ( according to such embodiment ) along the entire perimetral wall 8 .

[0083] Expediently, i f sealing member 10 only extends along first portion 8a of perimetral wall 8 , it also extends so as to abut onto the lateral walls of casing 2 .

[0084] Thanks to the presence of sealing member 10 , thermal barrier device 7 has the double function of thermally insulating the adj acent battery cells 3 from one another and of fluid-tight sealing the adj acent battery cells 3 from one another .

[0085] More particularly, their venting ports 6 are ef fectively sealed from one another, thereby signi ficantly reducing the risk of a chain ef fect in case a thermal runway event occurs for one of the battery cells 3 of battery pack 1 .

[0086] In fact , in case a thermal runway event occurs for one battery cell 3 , with hot high-pressure gases outflowing from the respective venting port 6 , sealing members 10 of the thermal barrier devices 7 arranged on the sides of such battery cell 3 confine such gases within the relative compartment 11 , thereby avoiding such chain ef fect .

[0087] In other words , devices 7 provided with sealing members 10 decrease the risk of a thermal runway event occurring for a battery cell 3 af fecting other battery cells 3 .

[0088] The li fespan of battery pack 1 is therefore increased .

[0089] Sealing member 10 is preferably made of elastomeric material .

[0090] Thermal barrier device 7 comprises at least a first layer 12 of temperature-resistant elastomeric material .

[0091] In detail , first layer 12 defines at least part of perimetral wall 8 , with respect to thickness direction T .

[0092] Sealing member 10 is advantageously fixed to first layer 12 .

[0093] Advantageously, first layer 12 includes silicone or silicone foam .

[0094] The Applicant has observed that such materials allow to reach the optimal compromise between the needed compressibility and thermal insulation .

[0095] In fact , a good compressibility of thermal barrier device 7 is desirable , other than its thermal insulation properties , due to a breathing and swelling cycle of the battery cells 3 better explained below .

[0096] Moreover, the improved compressibility of first layer 12 allows for an increased abutment of sealing member 10 against casing 2 , which further enhance the sealing of compartments 11 .

[0097] In other words , the more first layer 12 is compressed, the more sealing member 10 is compressed against casing 2 , and therefore the greater is the sealing ef fect .

[0098] In one embodiment , sealing member 10 and first layer 12 define two distinct pieces .

[0099] In one advantageous embodiment , sealing member 10 is made in one single piece without solution of continuity with first layer 12 . Thanks to this configuration, the production of thermal barrier layer 7 is eased as no assembly step is required between sealing member 10 and first layer 12 . Moreover, the risk of errors in relative positioning and / or coupling between first layer 12 and sealing member 10 is completely avoided, which results in a further improvement in the sealing properties .

[0100] According to one embodiment of the present invention, shown in Figure 3b, first layer 12 is three- dimensionally structured and includes a central planar base 14 and a plurality of protrusions 15 .

[0101] Protrusions 15 proj ect from both lateral sides of base 14 along thickness direction T , thereby defining a plurality of raised portions 15 extending towards the adj acent battery cells 3 , and in particular towards the side walls 3a of the battery cells 3 , respectively, and a plurality of recessed portions 16 delimited, each, by two contiguous raised portions 15 .

[0102] It is speci fied that raised portions 15 define the ( compression) load-bearing portions of first layer 12 according to this embodiment of the present invention .

[0103] As shown in Figure 3b, raised portions 15 and recessed portions 16 are arranged in an alternating manner .

[0104] Furthermore , the raised portions 15 extending from one lateral side of base 14 are preferably staggered with respect to the raised portions 15 extending from the other lateral side of base 14 , so that a raised portion 15 on one lateral side is aligned with a recessed portion 16 on the other lateral side , along thickness direction T .

[0105] In other words , first layer 12 according to such non-limiting embodiment has a sort of meandering structure . The alternance of raised portions 15 and recessed portions 16 and provides first layer 12 with enhanced mechanical properties , especially relative to its compressibility .

[0106] The aforementioned staggered disposition of raised portions 15 and recessed portions 16 further enhances such mechanical properties .

[0107] In particular, the Applicant has observed that the meandering structure further improves the compressibility of first layer 12 , without altering its thermal insulation properties .

[0108] More speci fically, recessed portions 16 act as insulating air cushions , which also provide for a better compressibility of first layer 12 , allowing for better withstanding the compression exerted by swelling battery cells 3 and reducing the load on sealing member 10 .

[0109] According to a preferred embodiment of the present invention, sealing member 10 presents a hollow crosssection and has an outer body delimiting an inner cavity, as shown in Figure 3a .

[0110] Thanks to this hollow configuration, the deformability of sealing member 10 under compression is improved . This implies that the sealing contact between sealing member 10 and casing 2 is more stable during operation of battery pack 1 .

[0111] In fact , it is known that during operation of battery pack 1 , the battery cells 3 undergo a sort of breathing and swelling cycle , whereby each battery cell 3 swells and contracts repeatedly .

[0112] The swelling of adj acent battery cells 3 implies a compression action on the thermal barrier device 7 interposed between them, which then causes a squeezing of thermal barrier device 7 transversally to the thickness direction T .

[0113] This transversal squeezing causes the perimetral wall 8 to move towards casing 2 , and therefore increases the abutting action of sealing member 10 towards casing 2 . Hence , the hollow configuration of sealing member 10 allows for absorbing the further compression without causing excessive deformations on the thermal barrier device 10 itsel f .

[0114] According to an alternative embodiment of the present invention, shown in Figure 4a, thermal barrier device 7 includes a sealing member 10 which comprises a first sealing lip 13a, a second sealing lip 13b and a middle sealing lip 13c arranged between first sealing lip 13a and second sealing lip 13b .

[0115] In other words , as shown in Figure 4a, sealing member 10 according to this embodiment is substantially Y- shaped, more precisely substantially ji-shaped .

[0116] In detail , first sealing lip 13a and middle seal ing lip 13c are arranged so that a f irst gap 17a is formed between them .

[0117] Similarly, second sealing lip 13b and middle sealing lip 13c are arranged so that a second gap 17b is formed between them .

[0118] First sealing lip 13a, second sealing lip 13b and middle sealing lip 13c are arranged in abutment against casing 2 , and in particular against its first internal wall 2a .

[0119] In this condition, first gap 17a and second gap 17b are closed, being delimited by first internal wall 2a .

[0120] Hence , middle sealing lip 13c seals in a fluid-tight manner first gap 17a from second gap 17b .

[0121] Moreover, first sealing lip 13a is interposed between a first battery cell 3 of the two adj acent cells 3 and first gap 17a, along thickness direction T , and seals in a fluid-tight manner such first battery cell 3 from first gap 17 .

[0122] Similarly, second sealing lip 13b is interposed between a second battery cell 3 of the two adj acent cells 3 and second gap 17b, along thickness direction T , and seals in a fluid-tight manner such second battery cell 3 from second gap 17b .

[0123] Preferably, such sealing member 10 has a symmetric configuration with respect to a central symmetry axis X, which preferably passes through middle sealing lip 13c .

[0124] The Applicant has observed that such multi-lip configuration of sealing member 10 further improves the sealing properties of thermal barrier device 7 .

[0125] In fact , the presence of a middle sealing lip 13c ensures a further level of sealing, should either of the first lip 13a or second lip 13b break or fail .

[0126] In this way, sealing member 10 is adapted to withstand higher pressures exerted from within compartments 11 , especially during a thermal runway event .

[0127] Moreover, first gap 17a and second gap 17b define further cavities which enhances the deformability of sealing member 10 against casing 2 .

[0128] Preferably, also such sealing member 10 has an inner cavity, thereby obtaining the same advantages listed above in connection with such feature .

[0129] According to a further alternative embodiment of the present invention, shown in Figure 4b, middle sealing lip includes a first middle sealing lip 13ca and a second middle sealing lip 13cb which are arranged between first sealing lip 13a and second sealing lip 13b .

[0130] In detail , first middle sealing lip 13ca is interposed between first sealing lip 13a and second middle sealing lip 13cb , and second middle sealing lip 13cb is interposed between second sealing lip 13b and first middle sealing lip 13ca, along thickness direction T .

[0131] In greater detail , a third gap 17c is defined between first middle sealing lip 13ca and second middle sealing lip 13cb .

[0132] First middle sealing lip 13ca seals in a fluid-tight manner first gap 17a from third gap 17c . Similarly, second middle sealing lip 13cb seals in a fluid-tight manner second gap 17b from third gap 17c .

[0133] Preferably, sealing member 10 has a symmetric configuration with respect to a central symmetry axis X, which preferably passes through third gap 17c .

[0134] The Applicant has observed that such multi-lip configuration of sealing member 10 improves even more the sealing properties of thermal barrier device 7 .

[0135] In fact , the presence of a first middle sealing lip 13ca and second middle sealing lip 13cb ensures two further level of sealing .

[0136] In this way, sealing member 10 is adapted to withstand even higher pressures exerted from within compartments 11 .

[0137] Moreover, third gap 17c defines a further cavity which enhances the deformability of sealing member 10 against casing 2 .

[0138] Preferably, also such sealing member 10 has an inner cavity, thereby obtaining the same advantages listed above in connection with such feature .

[0139] According to a preferred embodiment of the present invention, thermal barrier device 7 comprises a second layer 18 and a third layer 19 which are made of thermally insulating material and are stacked onto first layer 12 in the thickness direction T thereof so as to define said lateral surfaces 7a, 7b, respectively .

[0140] In detail , second layer 18 defines lateral surface 7a and third layer 19 defines lateral surface 7b .

[0141] In light of the above , first layer 12 defines an inner part of perimetral wall 8 , whereas second layer 18 and third layer 19 define together an outer part 8d of perimetral wall 8 , with respect to thickness direction T .

[0142] Conveniently, second layer 18 and third layer 19 comprise aerogel .

[0143] The Applicant has observed how the presence of aerogel signi ficantly improves the thermal insulating properties of thermal barrier device 7 .

[0144] Moreover, as aerogel is signi ficantly more thermally insulating than silicone , the thermal insulation function of device 7 is carried out by second layer 18 and third layer 19 , while the support and compression absorption function is carried out by first layer 12 .

[0145] Preferably, second layer 18 and third layer 19 include a carrier 20 comprising glass fibers , carrier 20 supporting the aerogel .

[0146] The presence of carrier 20 improves the stability of the aerogel and its fixation on first layer 12 .

[0147] According to a non-limiting advantageous embodiment , sealing member 10 extends on perimetral wall 8 covering only the aforementioned inner part of perimetral wall 8 , while leaving outer part 8d uncovered .

[0148] This peculiar configuration is shown in Figure 3c .

[0149] Thanks to this configuration, the compression stress generated by the abutment of sealing member 10 against casing 2 is transmitted only to first layer 12 , which being made of elastomeric material ( silicone or silicone foam) has a higher deformability than second layer 18 and third layer 19 (which are made in aerogel ) .

[0150] In this way, an excessive compress ion of second layer 18 and third layer 19 orthogonally to thickness direction T can be avoided, thereby limiting ruptures thereof .

[0151] Furthermore , a cyclical compression / decompression fatigue load onto second layer 18 and third layer 19 , due to the aforementioned swelling cycle of battery cells 3 , is avoided .

[0152] According to a further preferred embodiment of the invention, shown in Figure 3d, each one of the second layer 18 and third layer 19 comprises a coupling portion 21 and sealing member 10 comprises a receiving portion 22 engaged by the coupling portions 21 of second layer 18 and third layer 19 , so that second layer 18 and third layer 19 are fitted to sealing member 10 at perimetral wall 8 .

[0153] Preferably, also carriers 20 are fitted into receiving portion 22 .

[0154] In this way, a more stable coupling between the second and third layers 18 , 19 and the first layer 12 , that is between the aerogel material ( and the carrier material ) and the silicone material , can be obtained .

[0155] In one embodiment , thermal barrier device 7 comprises a foil element (not shown) , preferably made of polyethylene , wrapping first layer 12 , second layer 18 and third layer 19 .

[0156] Conveniently, the foil element wraps also sealing member 10 .

[0157] The presence of a foil element improves the robustness and stability of thermal barrier device 7 , as well as its resistance to wear, ultimately increasing its li fespan .

[0158] The advantages o f battery pack 1 and of thermal barrier device 7 according to the present invention will be clear from the foregoing description .

[0159] In particular, thanks to the presence of sealing member 10 , thermal barrier device 7 has the double function of thermally insulating the adj acent battery cells 3 from one another and of fluid-tight seal ing the adj acent battery cells 3 from one another .

[0160] More particularly, their venting ports 6 are ef fectively sealed from one another, thereby signi ficantly reducing the risk of a chain ef fect in case a thermal runway event occurs for one of the battery cells 3 of battery pack 1 .

[0161] In fact , in case a thermal runway event occurs for one battery cell 3 , with hot high-pressure gases outflowing from the respective venting port 6 , sealing members 10 of the thermal barrier devices 7 arranged on the sides of such battery cell 3 confine such gases within the relative compartment 11 , thereby avoiding such chain ef fect . The li fespan of battery pack 1 is therefore increased .

[0162] Clearly, changes may be made to battery pack 1 or thermal barrier device 7 as described herein without , however, departing from the scope of protection as defined in the accompanying claims .

Claims

CLAIMS1.- Electrical energy storage device (1) comprising a casing (2) , at least two electrical energy storage cells (3) enclosed within the casing (2) and arranged adjacent to one another, and at least one thermal barrier device (7) interposed and stacked between the storage cells (3) in a thickness direction (T) thereof and configured to thermally insulate the adjacent storage cells (3) , wherein the thermal barrier device (7) has a matlike configuration and includes two opposite lateral surfaces (7a, 7b) separated by a perimetral wall (8) defining the thickness of the thermal barrier device (7) ; wherein the thermal barrier device (7) comprises a sealing member (10) extending along at least part of the perimetral wall (8) and arranged in abutment against the casing (2) so as to seal in a fluid-tight manner the adjacent storage cells (3) from one another.2.- Electrical energy storage device as claimed in claim 1, wherein the thermal barrier device (7) defines two adjacent compartments (11) within the casing (2) , each compartment (11) housing one respective storage cell (3) , each compartment (11) being f luid-tightly sealed from the adjacent compartment (11) by means of the sealing member (10) .3.- Electrical energy storage device as claimed in claim 1 or 2, wherein each storage cell (3) has an operative wall (5) provided with a safety venting port (6) for allowing an outflow of gases from an inner environment of the storage cell (3) , the storage cells (3) being arranged so that their operative walls (5) face a first internal wall (2a) of the casing (2) ; wherein said perimetral wall (8) has a first portion (8a) facing the first internal wall (2a) of the casing (2) ; and wherein the sealing member (10) extends alongthe entire first portion (8a) and is arranged in abutment against the first internal wall (2a) , so as to seal in a fluid-tight manner the adjacent venting ports (6) from one another.4.- Electrical energy storage device as claimed in claim 3, wherein said perimetral wall (8) has a second portion (8b) opposite to said first portion (8a) and facing a second internal wall of the casing (2) opposite to the first internal wall (2a) ; wherein the sealing member (10) extends also along the entire second portion (8b) and is arranged in abutment against the second internal wall of the casing.5.- Electrical energy storage device as claimed in any one of the foregoing claims, wherein the sealing member (10) presents a hollow cross-section and has an outer body delimiting an inner cavity.6.- Electrical energy storage device as claimed in any one of the claims 1 to 4, wherein the sealing member (10) includes a first sealing lip (13a) , a second sealing lip (13b) and a middle sealing lip (13c) arranged between the first sealing lip (13a) and the second sealing lip (13b) , the first sealing lip (13a) and the middle sealing lip (13c) being arranged so that a first gap (17a) is formed between them, the second sealing lip (13a) and the middle sealing lip (13c) being arranged so that a second gap (17b) is formed between them, wherein the first sealing lip (13a) , the second sealing lip (13b) and the middle sealing lip (13c) are arranged in abutment against the casing (2) , wherein the middle sealing lip (13c) seals in a fluid-tight manner the first gap (17a) from the second gap (17b) , wherein the first sealing lip (13a) is interposedbetween a first storage cell (3) of the two adjacent storage cells (3) and the first gap (17a) , along said thickness direction (T) , and seals in a fluid-tight manner the first storage cell (3) from the first gap (17a) , wherein the second sealing lip (13b) is interposed between a second storage cell (3) of the two adjacent storage cells (3) and the second gap (17b) , along said thickness direction (T) , and seals in a fluid-tight manner the second storage cell (3) from the second gap (17b) .7.- Electrical energy storage device as claimed in claim 6, wherein the middle sealing lip includes a first middle sealing lip (13ca) and a second middle sealing lip (13cb) which are arranged between the first sealing lip (13a) and the second sealing lip (13b) , the first middle sealing lip (13ca) being interposed between the first sealing lip (13a) and the second middle sealing lip (13cb) , the second middle sealing lip (13cb) being interposed between the second sealing lip (13b) and the first middle sealing lip (13ca) , along the thickness direction (T) ; wherein a third gap (17c) is defined between the first middle sealing lip (13ca) and the second middle sealing lip (13cb) , wherein the first middle sealing lip (13ca) seals in a fluid-tight manner the first gap (17a) from the third gap (17c) , wherein the second middle sealing lip (13cb) seals in a fluid-tight manner the second gap (17b) from the third gap (17c) .8.- Electrical energy storage device as claimed in any one of the foregoing claims, wherein the thermal barrier device (7) comprises at least a first layer (12) of temperature-resistant elastomeric material; and wherein the sealing member (10) is fixed to said first layer ( 12 ) .9.- Electrical energy storage device as claimed in claim 8, wherein the first layer (12) includes silicone or silicone foam.10.- Electrical energy storage device as claimed in claim 8 or 9 wherein the sealing member (10) is made in one single piece without solution of continuity with said first layer ( 12 ) .11.- Electrical energy storage device as claimed in any one of the claims 8 to 10, wherein the first layer (12) is three-dimensionally structured and includes a central planar base (14) and a plurality of protrusions(15) which project from both lateral sides of the central planar base (14) along said thickness direction (T) , thereby defining a plurality of raised portions (15) extending towards the adjacent storage cells (3) , respectively, and a plurality of recessed portions (16) delimited, each, by two contiguous raised portions (15) ; the raised portions (15) and the recessed portions(16) being arranged in an alternating manner.12.- Electrical energy storage device as claimed in claim 11, wherein the raised portions (15) extending from one lateral side of the central planar base (14) are staggered with respect to the raised portions (15) extending from the other lateral side of the central planar base (14) , so that a raised portion (15) on one lateral side is aligned with a recessed portion (16) on the other lateral side, along the thickness direction (T) .13.- Electrical energy storage device as claimed in any one the claims 8 to 12, wherein the thermal barrier device (7) comprises a second layer (18) and a third layer (19) which are made of thermally insulating material and are stacked onto said first layer (12) in the thickness direction (T) thereof so as to define said lateral surfaces (7a, 7b) , respectively;wherein the first layer (12) defines an inner part of said perimetral wall (8) and the second layer (18) and third layer (19) define together an outer part (8d) of said perimetral wall (8) .14.- Electrical energy storage device as claimed in claim 13, wherein the sealing member (10) extends on said perimetral wall (8) covering only the inner part of said perimetral wall (8) , thereby leaving uncovered said outer part ( 8d) .15.- Electrical energy storage device as claimed in claim 13 or 14, wherein the second layer (18) and third layer (19) comprise aerogel.16.- Electrical energy storage device as claimed in claim 15, wherein the second layer (18) and third layer (19) include a carrier (20) comprising glass fibers, the carrier (20) supporting the aerogel.17.- Electrical energy storage device as claimed in any one of the claims 13 to 16, wherein each one of the second layer (18) and the third layer (19) comprises a coupling portion (21) and the sealing member (10) comprises a receiving portion (22) engaged by the coupling portions (21) of the second layer (18) and third layer (19) , so that the second layer (18) and the third layer (19) are fitted to the sealing member (10) at said perimetral wall (8) .18.- Electrical energy storage device as claimed in any one of the claims 13 to 17, wherein the thermal barrier device (7) comprises a foil element, preferably made of polyethylene, wrapping the first layer (12) , the second layer (18) and the third layer (19) ; wherein the foil element wraps also the sealing member (10) .19.- Electrical energy storage device as claimed in any one of the foregoing claims, and comprising more than two storage cells (3) arranged adjacent to one anotheralong the thickness direction (T) , and a plurality of thermal barrier devices (7) , each interposed and stacked between two adjacent storage cells (3) , with respect to the thickness direction (T) , each thermal barrier device (7) f luid-tightly sealing from one another the two respective storage cells (3) between which the thermal barrier device (7) is interposed .20.- Thermal barrier device (7) for an electrical energy storage device (1) comprising a casing (2) and at least two electrical energy storage cells (3) enclosed within the casing (2) and arranged adjacent to one another, the thermal barrier device (7) being configured to be interposed and stacked between the storage cells (3) in a thickness direction (T) thereof and to thermally insulate the adjacent storage cells (3) , the thermal barrier device (7) having a mat-like configuration and including two opposite lateral surfaces (7a, 7b) separated by a perimetral wall (8) defining the thickness of the thermal barrier device (7) , the thermal barrier device (7) comprising a sealing member (10) extending along at least part of the perimetral wall (8) and configured to be arranged in abutment against the casing (2) of the storage device (1) so as to seal in a fluid-tight manner the adjacent storage cells (3) from one another.

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