Preferably a one-piece valve body, battery cell, filling and / or degassing method for a battery cell and battery

Abstract

The invention relates to a one-piece valve body (1), a battery cell, a filling and / or degassing method for a battery cell and a battery, wherein the one-piece valve body (1) comprises a cap (2), a neck (3) and a head (4), wherein the valve body (1) comprises an inner channel (5) which extends through the valve body (1) such that the inner channel (5) has a first opening (5a) in the region of the cap (2) and that the inner channel (5) has a second opening (5b) in the region of the neck (3).

Description

[0001] The invention relates to a valve body, in particular a one-piece valve body, a battery cell, a filling and / or degassing method for a battery cell and a battery.

[0002] During the manufacturing of batteries, such as lithium-ion batteries, gases can form inside each battery cell. These gases must be vented from the interior. If the gas cannot be successfully vented, it will expand, which can seriously impair the properties and operation of the individual battery cell.

[0003] From DE 851 370 C a degassing plug for collector batteries is known, wherein a valve made of an elastic material, such as polyethylene, passes through a central opening of the plug body and closes this central opening with a widened plate part on the outlet side of the plug in a check valve-like manner.

[0004] The object of the invention is to propose a valve body, in particular a one-piece valve body, a battery cell, a filling and / or degassing method for a battery cell and a battery, by means of which not only degassing but also filling is possible.

[0005] This problem is solved by the characterizing features of claims 1, 7, 14, and 15, respectively, starting from the features of the preamble. Advantageous and expedient embodiments are specified in the respective dependent claims.

[0006] The valve body according to the invention comprises a cap, a neck, and a head, wherein the valve body includes an inner channel, the inner channel having a first opening in the region of the cap and the inner channel having a second opening in the region of the channel. The provision of an inner channel enables unobstructed passage in both a filling direction and a degassing direction, thus allowing for both the supply and discharge of a medium.

[0007] Furthermore, it is planned to provide the inner channel in the neck area with a third opening, the third opening forming an additional opening opposite the second opening. This creates a T-shaped inner channel in side view, through which a medium can flow in via the second and third openings for degassing and flow out via the first opening, or through which a medium can flow in via the first opening for filling and flow out via the second and third openings, thus enabling the connection of a filling and / or degassing device via the first opening.

[0008] The valve body is preferably manufactured as a single piece to ensure the required tightness, ease of handling, and cost-effective production. However, a multi-part design necessitated by manufacturing requirements is also conceivable.

[0009] It is also possible to form the inner channel with a blind hole and a through hole, wherein the blind hole extends from the top of the cap along a longitudinal axis of the valve body to the neck, and wherein the through hole is a transverse bore through the neck, with the blind hole opening into the through hole. This allows the inner channel to be manufactured simply by using two bores.

[0010] Furthermore, the cap can be designed as a bell-shaped body, extending over a portion of the neck towards the head with a bell-shaped outer shell. Through this bell-shaped shell, the valve body, in conjunction with a valve receptacle, functions as an elastic spring.

[0011] It is also possible to design the neck as a cylinder and to have the neck transition into the head with a rapidly increasing diameter, thereby forming an annular sealing and contact surface on the head opposite the cap. This gives the head the function of an anchor.

[0012] Furthermore, the valve body can be designed as a rotationally symmetric body with respect to its longitudinal axis. This simplifies the installation of the valve body, as it is not necessary to pay attention to a specific rotational orientation of the valve body.

[0013] The battery cell according to the invention comprises a valve body and a housing, wherein the housing comprises a basin and a lid with an opening, wherein the valve body is formed in one piece and comprises a cap, a neck and a head, wherein the valve body, in the assembled state, rests directly against a top surface of the lid with its cap, wherein the valve body, in the assembled state, rests directly against a bottom surface of the lid with its head, wherein, in the assembled state of the valve body, a cavity is formed between the cap and the neck of the valve body and the top surface of the lid, wherein the valve body comprises an inner channel which extends through the valve body, wherein the inner channel opens into the cavity in the region of the neck of the valve body.wherein the inner channel opens into an environment outside the cavity in the area of ​​the cap, and wherein the cap is deformable by a pressure force acting on it in the direction of the lid such that the neck can be pushed through the opening in the lid far enough that the inner channel, with its second opening, opens at least partially into an interior of the housing. This allows a connection between an interior of the housing and an environment of the housing to be established by means of the inner channel by applying a force to the valve body in the direction of its longitudinal axis towards the housing. Accordingly, with such deformation of the valve body, it is possible to fill or degas the housing.

[0014] Furthermore, the cap can be designed with a bell-shaped casing, the bell-shaped casing being designed such that, when the valve body is mounted, a contact surface of its circumferential casing edge rests against the top of the cover. This seals the cavity from the environment.

[0015] It is also possible to provide a recess on the upper side of the lid in the area of ​​the opening, with the recess being dimensioned such that the bell-shaped casing rests against the lid with its hem outside the recess. Such a recess increases the volume of the cavity without altering the dimensions of the bell-shaped casing. Thus, the cavity can be adjusted in a material-saving manner simply by lengthening the neck. Accordingly, the elastic spring behavior of the valve body is independent of any requirement for the volume of the cavity.

[0016] Furthermore, the lid may be designed with a recess on its upper surface in the area of ​​the opening, whereby the valve body, when mounted and depressed, rests against the upper surface of the lid with a stop surface of its cap core in the area of ​​the recess. The positioning of this stop surface determines how deeply the head can be pressed into the interior of the housing. The distance between the stop surface and the second opening of the inner channel, or the second and third openings of the inner channel, further determines the extent to which the second opening, or the second and third openings, are immersed in the interior of the housing when the valve body is depressed for filling or venting.

[0017] It may also be possible to adapt the cross-section of the lid opening to the neck cross-section of the received valve body with respect to cross-sectional shape and cross-sectional area. This creates an additional seal on the lid.

[0018] It may also be provided that the diameter of the transverse bore is adapted to the thickness of the cover in the area of ​​the opening in such a way that, in no position of the valve body, the transverse bore creates a connection between the interior of the housing and the cavity between the neck, the bell mantle and the cover.

[0019] Furthermore, it may be possible to design the one-piece valve body according to at least one of claims 1 to 6. This results in the advantages mentioned in these claims in an analogous manner. This prevents degassing of the housing into the cavity.

[0020] The filling and / or degassing method according to the invention for a battery cell, which is designed according to at least one of claims 7 to 12, comprises the following steps: - the valve body is pressed down towards the lid by means of a filling and / or degassing device, which is designed in particular as a filling device or as a degassing device or as a combined filling and / or degassing device, to such an extent that the neck of the valve body is pressed through the opening of the lid into the interior of the battery cell to such an extent that it becomes accessible via the inner channel of the valve body; - optionally, at least one process from the group of processes degassing process, filling process is carried out, ◯ wherein a medium is withdrawn from the interior during the degassing process by the filling and / or degassing device through the inner channel of the valve body or ◯ wherein a medium is supplied to the interior during the filling process from the filling and / or degassing device through the inner channel of the valve body; - the valve body is relieved, whereby as a result the neck is pulled so far out of the opening by the cap which is supported on the top of the lid that the head is drawn sealingly against the underside of the lid.

[0021] This filling and / or degassing process makes it possible to perform both filling and degassing operations using the same one-piece valve body.

[0022] The battery according to the invention comprises a plurality of battery cells according to at least one of claims 7 to 12. Accordingly, the advantages mentioned in relation to the claims in question arise for the battery in an analogous manner.

[0023] Further details of the invention are described in the drawing with reference to a schematically illustrated embodiment.

[0024] This shows: Fig. 1: a side view of a valve body according to the invention; Fig. 2: a top view of the one in the Fig. 1 valve body shown; Fig. 3: a cross-section of the area in the Fig. 1 valve body shown according to the one in the Fig. 1 section line shown III-III; Fig. 4: a battery cell which stores the energy from the Fig. comprising 1 to 3 known valve bodies and a housing, wherein the valve body is not actuated; Fig. 5: a representation according to the Fig. 4, wherein the valve body is actuated by a filling and / or degassing device; Fig. 6: a battery.

[0025] In the Fig. Figure 1 shows a side view of a valve body 1 according to the invention. The valve body 1 is formed in one piece and comprises a cap 2, a neck 3 and a head 4. Furthermore, the valve body 1 comprises an inner channel 5.

[0026] In the Fig. 2 is a top view of the [object] in the Fig. Valve body 1 is shown. Fig. Figure 3 shows a section through the valve body according to the one in the Fig. 1. Section line III-III is shown.

[0027] From a synthesis of Fig. Figures 1 to 3 show the course of the inner channel 5. The inner channel 5 has a first opening 5a in the area of ​​the cap 2 and a second opening 5b and a third opening 5c ​​in the area of ​​the neck 3. The third opening 5c ​​is designed as an additional opening, which is opposite the second opening 5b.

[0028] In terms of manufacturing, the inner channel 5 can be formed by a blind bore 6 and a through bore 7. The blind bore 6 extends from a top surface 8 of the cap 2 along a longitudinal axis L1 of the valve body 1 into the neck 3. The through bore 7 extends as a transverse bore 9 through the neck 3 to the blind bore 6, with the blind bore 6 opening into the through bore 7.

[0029] According to the Fig. 1. The through-hole 7 has a circular cross-section. According to the Fig. 2 The blind hole bore 6 has a rectangular cross-section.

[0030] In the illustrated embodiment, the valve body 1 is made of an acid-resistant synthetic rubber, in particular an ethylene propylene diene monomer rubber. Other materials are also conceivable, provided they meet the necessary properties. The valve body 1 has a Shore hardness of 70 to 90 Sh, and in particular 80 Sh.

[0031] The cap 2 of the valve body 1 is designed as a bell-shaped body 10, which extends with a bell mantle 11 in the x-direction towards the head 4 over a remote area 12 of the neck 3.

[0032] The neck 3 is designed as a cylinder 13 and transitions into the head 4 with a rapidly increasing diameter. This abrupt transition creates an annular sealing and contact surface 14 on the head 4 opposite the cap 3.

[0033] The valve body 1 is designed as a rotationally symmetric body K with respect to its longitudinal axis L1, which has the inner channel 5.

[0034] In the Fig. 4 is the one from the Fig. The valve body 1, known from Figures 1 to 3, is shown again in section, wherein the valve body 1 is mounted on a housing 100, which comprises a basin 101 and a cover 102. The battery cell BZ1 according to the invention comprises the valve body 1 and the housing 100. The cover 102 has a recess 103 in which an opening 104 is formed. During assembly, the head 4 of the valve body 1 is pressed through this opening 104 towards the cover 102 by applying pressure to the cap 2 of the valve body 1, so that the cover, with its annular sealing and contact surface 14, rests against a lower surface 102b of the cover 102 when no external pressure is applied to the cap 2. During assembly, the bell-shaped casing 11 of the cap 2 is also spread open. As the pressure decreases, the bell-shaped mantle 11 reverts to its original shape, thereby pulling the head 4 with its sealing and contact surface 14 against the underside 102b of the cover 102.The cover 102 forms a receptacle A1 for the valve body 1. Furthermore, the cover 102 together with the valve body 1 forms a valve V.

[0035] The cover 102 and the valve body 1 are dimensionally matched such that a distance A102 between a top surface 102a of the cover 102 outside the recess 103 and a bottom surface 102b of the cover 102 in the area of ​​the recess 103 is greater than a distance A14 between a circumferential contact surface KF11 of the bell housing 11 and the sealing and contact surface 14 of the head 4, which is measured in an unmounted state of the valve body 1 (see Fig. 1) Accordingly, the valve body 1 is positioned after assembly (as shown in the Fig. (4 shown) under a preload, so that the head 4 is pulled upwards in a direction x' by the bell-shaped shell 11 of the cap 2, since the bell-shaped shell 11, which is elastically deformed during assembly, tends to return to its original shape. Fig. to assume the form shown in 1 to 3.

[0036] In the Fig. 5 is a representation according to the Fig. 4 can be seen, wherein the valve body 1 is actuated by a filling and / or degassing device 401, which is only schematically indicated in the drawing, such that the valve body 1 is pressed down onto the lid 102 in the x-direction.

[0037] In the Fig. Figure 5 shows the housing 100 in its entirety. An interior space 105 of the housing 100 is filled with an electrolyte 107 up to a fill level 106. Since the housing 100 of the battery cell BZ1 was freshly filled, gas 108 has accumulated above the electrolyte 107.

[0038] Compared with the Fig. Figure 4 clearly shows how the cap 2 is deformed in the area of ​​its bell-shaped mantle 11 by being pressed down. The pressing down causes the neck 3 and the head 4 to be pushed through the opening 104 of the cover 102 into the interior 105 of the housing 100 of the battery cell BZ1 to such an extent that the second and third openings 5b, 5c of the inner channel 5 of the valve body 1 are immersed in the interior 105. Accordingly, gas 108 can be drawn from the interior 105 through the inner channel 5 into the filling and / or degassing device 401, so that no unwanted overpressure builds up in the interior 105.

[0039] Excessive depressing of the valve body 1 is prevented by a stop formed at the transition of the neck 3 into the cap 2 by a core 15 of the cap 2 (see also to Fig. 5 also Fig. 3) The neck 3 transitions into the cylindrically shaped core 15 of the cap 2 above the through-bore 7. The cylindrically shaped neck 3 has a diameter D3, and the core 15 has a diameter D15. The transition from diameter D3 to the larger diameter D15 is abrupt. Accordingly, the core 15 has an annular stop surface 16 facing a top surface 102a of the cover 102. With this stop surface 16, the core 15 of the cap 2 rests on the top surface 102a of the cover 102 in the area of ​​the recess 103 when the valve body 1 is pressed down by the filling and / or degassing device 401. By measuring a distance A16-7 along the longitudinal axis L1 of the valve body 1 between the stop surface 16 and a longitudinal axis L7 of the through-bore 7 (see Fig. 3) It is defined how deep the second and third openings 5b, 5c or the through-bore 7 are immersed in the interior 105 when the valve body 1 is pressed down by the filling and / or degassing device 401.

[0040] From the Fig. 4 states the following with regard to a mounted state of the valve body 1 in which it is not depressed: In its assembled state, the valve body 1, with its cap 22, namely with a circumferential mantle rim 11a of the bell mantle 11, lies directly against the top 102a of the cover 102.

[0041] In its assembled state, the valve body 1 rests with its head 4, namely its sealing and contact surface 14, directly against the underside 102b of the cover 102.

[0042] In the assembled state of the valve body 1, a cavity H is formed between the cap 2 and the neck 3 of the valve body 1 and the top 102a of the cover 102.

[0043] In its assembled state, the inner channel 5 connects the cavity H with an environment U.

[0044] From the Fig. 5 states the following with regard to a mounted state of the valve body 1 in which it is depressed: The cap 2 is deformed by a pressure force F acting on it in the direction of the lid 102 in the area of ​​its bell-shaped mantle 11 in such a way that the neck 3 is pushed so far through the opening 104 of the lid 102 that the inner channel 5 with its second and third openings 5b, 5c partially opens into the interior 105 of the housing 100 of the battery cell BZ1.

[0045] The Fig. 4 and Fig. Figure 5 shows the cover 102 in a sectional view, with the aforementioned recess 103 on its upper surface 102a in the area of ​​the opening 104. The recess 103 is circular when viewed in the direction of the longitudinal axis L1 of the valve body 1. Furthermore, the recess 103 is dimensioned such that the bell-shaped casing 11 of the cap 2 of the valve body 1, with a circumferential rim 11a forming the contact surface KF11, rests against the cover 102 outside the recess 103. In this respect, the aforementioned cavity H is enlarged by the recess 103.

[0046] The opening 104 of the cover 102 corresponds to the neck 3 of the valve body 1 with respect to its cross-sectional shape and cross-sectional area.

[0047] A diameter D7 (see Fig. 3) A transverse bore 9 formed by the through bore 7 is adapted to a thickness A103 of the cover 102, which it has in the area of ​​the opening 104. Here, the diameter D7 is smaller than the thickness A103 of the cover. Accordingly, in no position of the valve body 1 or the neck 3 is a connection established by the transverse bore 9 between the interior 105 of the housing 100 of the battery cell BZ1 and the cavity H, which is formed between the neck 3, the bell casing 11 and the cover 102.

[0048] In the Fig. Figure 6 shows an exemplary battery B, which consists of the Fig. 4 and Fig. It is formed from 5 known battery cells BZ1 and two further, identical battery cells BZ2 and BZ3.

[0049] The ones from the Fig. 5 known filling and / or degassing device 401 is in the Fig. 6 shown in more detail. In the Fig. Figure 5 shows how the filling and / or degassing device 401 pushes the valve bodies of all three battery cells BZ1, BZ2 and BZ3 downwards. In the Fig. 6 is, by way of example, only the valve body 1 of the first battery cell BZ1. All three battery cells BZ1, BZ2 and BZ3 are vented by the filling and / or degassing device 401.

[0050] The filling and / or degassing method according to the invention for a battery cell BZ1 according to at least one of claims 7 to 12 comprises the steps: The valve body 1 is pressed down towards the lid 102 by means of a filling and / or degassing device 401 so far that the neck 3 of the valve body 1 is pressed through the opening 104 of the lid 102 into an interior 105 of the battery cell BZ1 so far that it becomes accessible via the inner channel 5 of the valve body 1.

[0051] Alternatively, at least one process from the group of processes degassing process, filling process is carried out: During the degassing process, a medium, in particular gas 108, is taken from the interior 105 by the filling and / or degassing device 401 through the inner channel 5 of the valve body 1. During the filling process, a medium, in particular electrolyte 107, is supplied to the interior 105 from the filling and / or degassing device 401 through the inner channel 5 of the valve body 1.

[0052] After the filling and / or degassing process, the valve body 1 is relieved, whereby the neck 3 is pulled out of the opening 104 from the cap 2, which is supported on the top 102a of the lid 102, to such an extent that the head 4 is drawn sealingly against the underside 102b of the lid 102. Reference symbol list 1 Valve body 2 caps from 1 3 necks of 1 4 heads out of 1 5 inner channel of 1 5a first opening of 5 5b second opening of 5 5c third opening of 5 6 blind hole drilling 7 through holes 8 Top of 2 9 transverse bore formed by 7 10 bell-shaped bodies 11 Bell Mantle 11a circumferential hem of 11 12 far-head area of ​​3 13 cylinders 14 sealing and contact surfaces of 4 15 core of 2 16 stop surface of 15 100 cases 101 tubs out of 101 102 lids out of 101 102a Top side of 101b 102b Underside of 101b 103 In-depth study 104 Breakthrough 105 interior of 101 106 Filling level 107 Electrolyte 108 Gas 401 Filling and / or degassing device A1 recording for 1 A14 Distance between 14 and KF11 A16-7 Distance between 16 and L7 of 7 A102 Distance between 102a and 102b BZ1 first battery cell BZ2 second battery cell BZ3 third battery cell D3 diameter of 2 D7 diameter of 7 or 9 D15 Diameter of 15 F Pressure force H cavity between 2 and 3 and 102 K rotationally symmetric body KF11 contact surface L1 Longitudinal axis of 1 L7 Longitudinal axis of 7 U surroundings V valve x direction downwards x' direction upwards QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 851 370 C

[0003]

Claims

[1] Valve body (1), preferably a one-piece valve body (1) comprising a cap (2), a neck (3) and a head (4), characterized by , - that the valve body (1) includes an inner channel (5) which runs through the valve body (1) in such a way that - that the inner channel (5) has a first opening (5a) in the area of ​​the cap (2), - that the inner channel (5) has a second opening (5b) in the area of ​​the neck (3). [2] Valve body according to claim 1, characterized by , that the inner channel (5) in the region of the neck (3) includes an additional opening as a third opening (5c), the additional opening being opposite the second opening (5b). [3] Valve body according to claim 1, characterized by, that the inner channel (5) is formed by a blind bore (6) and a through bore (7), wherein the blind bore (6) extends from a top (8) of the cap (2) along a longitudinal axis (L1) of the valve body (1) into the neck (3) and wherein the through bore (7) is designed as a transverse bore (9) through the neck (3) such that the blind bore (6) opens into the through bore (7). [4] Valve body according to at least one of the preceding claims, characterized by , that the cap (2) is designed as a bell-shaped body (10) which extends with a bell-shaped mantle (11) towards the head (4) over an area of ​​the neck (3). [5] Valve body according to at least one of the preceding claims, characterized by, that the neck (3) is designed as a cylinder and that the neck (3) transitions into the head (4) with a rapidly increasing diameter, whereby this is done in such a way that an annular sealing and contact surface (14) is formed on the head (4) opposite the cap (2). [6] Valve body according to at least one of the preceding claims, characterized by , that the valve body (1) is designed as a rotationally symmetric body with respect to its longitudinal axis (L1). [7] Battery cell (BZ1) comprising a valve body (1) and a housing (100) which includes a tray (101) and a lid (102) with an opening (104), wherein the valve body (1) is preferably formed in one piece and comprises a cap (2), a neck (3) and a head (4), characterized by , - that the valve body (1) in the assembled state with its cap (2) rests directly against a top surface (102a) of the cover (102), - that the valve body (1) in the assembled state with its head (4) rests directly against a bottom side (102b) of the cover (102), - that in the assembled state of the valve body (1) a cavity (H) is formed between the cap (2) and the neck (3) of the valve body (1) and the top (102a) of the cover (102), - that the valve body (1) includes an inner channel (5) which runs through the valve body (1), - wherein the inner channel (5) opens into the cavity (H) in the area of ​​the neck (3) of the valve body (1), - wherein the inner channel (5) opens into an environment (U) outside the cavity (H) in the area of ​​the cap (2), - wherein the cap (2) is deformable by a pressure force (F) acting on it in the direction of the lid (102) in such a way that the neck (3) can be pushed through the opening (104) of the lid (102) so far that the inner channel (5) with its second opening (5b) opens at least partially into an interior space (105) of the housing (100) of the battery cell (BZ1). [8] Battery cell according to claim 7, characterized by , that the cap (2) comprises a bell-shaped mantle (11), wherein the bell-shaped mantle (11) is designed such that, when the valve body (1) is mounted, it rests against the top (102a) of the cover (102) with a contact surface (KF11) of its circumferential mantle edge (11a). [9] Battery cell according to claim 8, characterized by, that the lid (102) on its upper side (102a) in the area of ​​the opening (104) includes a recess (103), wherein the recess (103) is dimensioned such that the bell mantle (11) with its mantle hem (11a) rests against the lid (102) outside the recess (103). [10] Battery cell according to at least one of the preceding claims 7 to 9, characterized by , that the lid (102) has a recess (103) on its upper side (102a) in the area of ​​the opening (104), wherein the valve body (1) in the mounted and depressed state rests against the upper side (102a) of the lid (102) with a stop surface (16) of a core (15) of its cap (2) in the area of ​​the recess (103). [11] Battery cell according to at least one of the preceding claims 7 to 10, characterized by, that a cross-section of the opening (104) of the cover (102) corresponds to a cross-section of the neck (3) of the received valve body (1) with respect to a cross-sectional shape and a cross-sectional area. [12] Battery cell according to at least one of the preceding claims 7 to 11, characterized by , that a diameter (D7) of the transverse bore (7) is adapted to a thickness (D102) of the cover (102) in the area of ​​the opening (104) such that the transverse bore (7) does not create a connection between the interior (105) of the battery cell (BZ1) and the cavity (H) between the neck (3), the bell casing (11) and the cover (102) in any position of the valve body (1). [13] Battery cell according to at least one of the preceding claims 7 to 12, characterized by , that the one-piece valve body (1) is designed according to at least one of claims 1 to 6. [14] Filling and / or degassing method for a battery cell (BZ1) according to at least one of claims 7 to 12 comprising the steps: - that the valve body (1) is pressed down towards the lid (102) by means of a filling and / or degassing device (401) to such an extent that the neck (3) of the valve body (1) is pressed through the opening (104) of the lid (102) into an interior space (105) of the battery cell (BZ1) to such an extent that the inner channel (5) of the valve body (1) becomes accessible; - that at least one process from the group of processes degassing process, filling process is carried out, ◯ wherein a medium is withdrawn from the interior (105) during the degassing process by the filling and / or degassing device (401) through the inner channel (5) of the valve body (1) or ◯ wherein a medium is supplied to the interior (105) during the filling process from the filling and / or degassing device (401) through the inner channel (5) of the valve body (1); - that the valve body is relieved, whereby as a result the neck (3) is pulled so far out of the opening (104) by the cap (2) which is supported on the top (102a) of the cover (102) that the head (4) is drawn sealingly against the underside (102b) of the cover (102). [15] Battery, characterized by that the battery comprises a plurality of battery cells according to at least one of claims 7 to 12.

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