Electrochemical cell assembly

Abstract

The invention relates to an electrochemical cell assembly (10), comprising a base plate, an end plate (26), a stack (12) comprising a plurality of cell units (14) stacked upon one another, said stack (12) being arranged between said base plate and said end plate, and an electrically conductive power transmission device (38) comprising a connector (40) that is located on a side of the end plate that is facing away from the stack, the power transmission device spanning the end plate and being electrically connected to the stack, wherein the power transmission device is attached to the end plate by a fastening device (42) at a portion of the power transmission device that is located between an electrical connection to the stack and the connector.

Description

[0001] Description

[0002] Title

[0003] State of the Art

[0004] The invention relates to the field of electrochemical cell stacks, in particular fuel cell stacks and electrolyser cell stacks. More specifically, the invention relates to an electrochemical cell assembly.

[0005] Fuel cells and electrolyser cells are examples of electrochemical cells. Fuel cells are energy conversion devices that allow for conversion of an electrochemical fuel (e.g. H2) to electricity. Electrolyser cells are fuel cells running in reverse mode, i.e. using electricity to decompose a chemical (e.g. H2O) into its constituent parts (e.g. H2 and O2). Reversible cells are capable of operating in both modes. Such electrochemical cells typically comprise cell chemistry layers that may be configured to allow for conversion of electrochemical fuel to electricity (fuel cells) or for decomposing a chemical into its constituent parts using electricity (electrolyser cells).

[0006] The present invention specifically relates to solid oxide cells (SOCs). Such solid oxide cells (SOCs) typically comprise an electrolyte layer formed from a solid oxide, e.g. Yttria-stabilised zirconia (YSZ), Gadolinia-doped Ceria, or Cerium Gadolinium Oxide (CGO). SOCs can be run as solid oxide fuel cell (SOFC) or as solid oxide electrolyser cell (SOEC).

[0007] Typically, multiple of such cell units are stacked upon one another to form a "stack" of cell units, also referred to as 'cell repeat units'. Said stack is commonly arranged between an end plate and a base plate that are provided on opposite sides of the stack, thus forming an electrochemical cell assembly. An electrochemical cell assembly of the above-described type is disclosed in WO 2015 / 136295 A1 , for example.

[0008] Description of the Invention

[0009] According to the invention, there is provided an electrochemical cell assembly with the features of claim 1. The electrochemical cell assembly comprises a base plate assembly having a base plate, an end plate assembly having an end plate, and a stack of cell units arranged between the base plate and the end plate. The stack of cell units comprises a plurality of cell units stacked upon one another along a stacking direction. Preferably, the stack of cell units is held in compression between the base plate and the end plate. The electrochemical cell assembly further comprises an electrically conductive power transmission device. The electrically conductive power transmission device comprises a connector that is located on a side of the end plate that is facing away from the stack of cell units. The power transmission device spans the end plate along the stacking direction and is electrically connected to the stack of cell units. The power transmission device, particularly its connector, may be configured to establish an electrical connection of the stack of cell units with an external device, e.g. an electrical energy storage device or a work machine to be driven by the electrochemical cell assembly. The power transmission device is attached to the end plate by a fastening device at a portion of the power transmission device that is located between an electrical connection of the power transmission device to the stack of cell units and the connector. During operation of the electrochemical cell assembly, an electrical current flowing from the stack of cell units to the connector of the power transmission device or from the connector of the power transmission device to the stack of cell units may consequently pass the portion of the power transmission device at which the power transmission device is attached to the end plate. Preferably, the power transmission device is biased towards the end plate by the fastening device.

[0010] The proposed configuration protects the stack of cell units during electrically connecting the connector of the power transmission device with an external device. Specifically, by the proposed attachment of the power transmission device to the end plate via the fastening device, forces applied to the connector in the course of establishing said electrical connection with an external device (e.g. push forces, pull forces and torques) are, preferably entirely, transmitted to the end plate. Thus, the proposed configuration avoids forces applied to the connector being transmitted to the stack of cell units, which otherwise may lead to displacement of components inside the stack of cell units and thus to potential leakage. The electrical connection with the external device is facilitated by the position of the connector of the power transmission device. Since the connector is located on the side of the end plate that is facing away from the stack of cell units, i.e. the end plate is located between the stack of cell units and the connector of the power transmission device, the connector is easily accessible for establishing an electrical connection with an external device.

[0011] Preferably, the power transmission device spans the end plate along the stacking direction by extending through a through-hole that is formed in the end plate. Alternatively, the power transmission device may also span the end plate along the stacking direction by extending along an outer perimeter of the end plate.

[0012] Preferably, the cell units of the stack of cell units are electrically connected in series. This facilitates the electrical connection of all cell units with the power transmission device. Each cell unit may extend in a cell plane perpendicular to the stacking direction. Thus, each cell unit may extend in a first direction, preferably a length direction, and in a second direction, preferably a width direction, that is perpendicular to the first direction. The first and second directions define said cell plane and are perpendicular to the stacking direction. The cell units may be configured flat or planar, each cell unit being in surface contact with the adjacent cell units. This surface contact may establish the electrical connection between adjacent cell units, in order to electrically connect the cell units in series.

[0013] The connector may be configured in different ways that allow for an electrical and particularly mechanical connection of the connector with a power transmission device of an external device. In one example, the connector is configured as a plug connector. Alternatively, the connector is configured to be connected to a power transmission device of an external device by at least one fastening element such as a screw or a bolt. This allows a robust mechanical connection of the connector with a power transmission device of an external device. For this purpose, the connector may comprise one or more through-holes formed therein. Preferably, the connector comprises a flat contact surface. This allows an electrical connection having a small resistance value, namely by establishing a surface contact between the flat contact surface of the connector and a flat contact surface of a power transmission device of an external device.

[0014] The electrical connection of the stack of cell units with the power transmission device may be realised in different ways. Preferably, the electrochemical cell assembly comprises an electrically conductive first transmission plate that is allocated to the power transmission device and arranged between the end plate and the stack of cell units. Said first power transmission plate is electrically connected to the stack of cell units and electrically connected to the power transmission device. That is to say, the power transmission device may be electrically connected to the stack of cell units by means of the first power transmission plate.

[0015] In some preferred embodiments, the power transmission device comprises a first power transmission member that is located on the side of the end plate that is facing away from the stack of cell units, said first power transmission member being attached to the end plate by the fastening device. Thus, the first power transmission member comprises the portion of the power transmission device at which the power transmission device is attached to the end plate by the fastening device. Since the first power transmission member is located on the side of the end plate that is facing away from the stack, i.e. outside of a receiving volume formed between the base plate and the end plate, the attachment of the first power transmission member to the end plate is facilitated. Furthermore, a compact electrochemical cell assembly can be realised because no space has to be held available for the first power transmission member and the fastening device within the receiving volume formed between the end plate and the base plate.

[0016] In some preferred embodiments, the first power transmission member is configured as a deformable power transmission tab. A tab is a flat element, i.e. an element that has a large width and a large length compared to its thickness. The small thickness of the power transmission tab has the advantage that the power transmission tab can be easily deformed in order to compensate for an expansion of elements of the electrochemical cell assembly along the stacking direction, e.g. due to an increase in temperature of said elements during use of the electrochemical cell assembly. The large width of the power transmission tab goes along with a small resistance value, compared to a first power transmission member having the same thickness but a smaller width.

[0017] In some preferred embodiments, the power transmission tab comprises a deformation section that is arranged in parallel with the end plate. Such an arrangement of the deformation section facilitates the deformation of the power transmission tab outlined above. Alternatively, the deformation section may be at an angle with respect to the end plate, particularly at an angle of 45° or less.

[0018] In some preferred embodiments, the power transmission tab has a thickness of at most 3.0 mm. A thickness of 3.0 mm or less facilitates the desired deformation of the power transmission tab, particularly the deformation section. Preferably, the power transmission tab has a thickness of at most 2.0 mm, most preferably at least 0.5 mm and at most 2.0 mm.

[0019] In some preferred embodiments, the power transmission tab has a width of at least 1.0 cm. The width of the power transmission tab is the dimension of the power transmission tab that extends perpendicularly to a current flow direction of an electrical current flowing between the connector of the power transmission device and the stack of cell units. A width of 1.0 cm or more results in an advantageously small resistance value. Preferably, the power transmission tab has a thickness of at least 2.0 cm.

[0020] In some preferred embodiments, the connector is formed by a folded edge of the power transmission tab. That is to say, the portion at which the power transmission device is attached to the end plate and the connector of the power transmission device are provided by the same member of the power transmission device, namely the power transmission tab. This reduces the amount of separate members required for the power transmission device. Furthermore, the provision of a folded edge in the first power transmission member or power transmission tab facilitates the connection of the connector with an external device. Preferably, the fold of the power transmission tab extends away from the end plate, most preferably perpendicularly to the end plate. In some preferred embodiments, the fastening device comprises a fastening member extending through a through-hole formed in the power transmission device, particularly a through-hole formed in the deformation section of the power transmission tab, and into a recess formed in the end plate. The fastening member is held in the recess by the end plate. This configuration of the involved elements results in a mechanically robust attachment of the power transmission device to the end plate. Preferably, the fastening device is configured as a screw and screwed into a threaded recess formed in the base plate. This has the advantage that a desired bias acting on the power transmission device and in the direction of the end plate can be precisely adjusted.

[0021] In some preferred embodiments, the fastening member is surrounded by a first insulating sleeve formed from an electrically insulating material, said first insulating sleeve electrically insulating the fastening member from the power transmission device. The presence of the first insulating sleeve allows the use of an electrically conductive metal material for the fastening member. Preferably, the electrically insulating material of the first insulating sleeve comprises or consists of at least one mineral from the mica group, particularly muscovite and / or phlogopite.

[0022] In some preferred embodiments, the cell assembly comprises a first support sleeve formed from a ceramic material, said first support sleeve surrounding the fastening member and being arranged between the end plate and the power transmission device, particularly between the end plate and the deformable section of the power connector tab. The first support sleeve secures a distance between the power transmission device, particularly the deformable section of the power transmission tab, and the end plate. An undesired contact between those elements might otherwise result in an electrical short circuit. Preferably, the ceramic material of the first support sleeve comprises or consists of alumina. Preferably, the power transmission device is biased against the first support sleeve. In case that the above-mentioned first insulating sleeve is provided, the first support sleeve preferably surrounds the first insulating sleeve.

[0023] In some preferred embodiments, the cell assembly comprises a second support sleeve formed from a ceramic material, said second support sleeve surrounding the fastening member and being arranged between the power transmission device and a stop provided by a head of the fastening member, particularly between the deformable section of the power transmission tab and the stop provided by the head of the fastening member. The second support sleeve secures a distance between the power transmission device, particularly the deformable section of the power transmission tab, and the head of the fastening member. An undesired contact between those elements might otherwise result in an electrical short circuit. Preferably, the ceramic material of the second support sleeve comprises or consists of alumina. Preferably, the head of the fastening member is biased against the second support sleeve. In case that the above- mentioned first insulating sleeve is provided, the second support sleeve preferably surrounds the first insulating sleeve.

[0024] In some preferred embodiments, the coefficient of thermal expansion of the material of the fastening member is higher than the coefficient of thermal expansion of the ceramic material of the first support sleeve and / or higher than the coefficient of thermal expansion of the ceramic material of the second support sleeve. This allows to compensate for thermal expansion occurring during use of the electrochemical cell assembly. Specifically, during use of the electrochemical cell assembly parts of the electrochemical cell assembly that are connected to the power transmission device (e.g. busbars connecting power transmission plates of the cell assembly) may undergo thermal expansion (operating temperatures may reach 500 °C and above), which may lead to undesired stresses. If the coefficient of thermal expansion of the material of the fastening member is higher than the coefficient of thermal expansion of the material of the support sleeves, the fastening member will expand during use more than the support sleeves, resulting in the attachment of the power transmission device to the end plate being slightly loosened. Thus, the power transmission device is slightly movable with respect to the end plate and can compensate for the thermal expansion of, e.g., the above-mentioned bus bars. Preferably, the coefficient of thermal expansion of the material of the fastening member is higher than the coefficient of thermal expansion of the ceramic material of the support sleeves by at least 2*10'6K'1. Preferably, the fastening member is formed from austenitic stainless steel, i.e. the material of the fastening member is austenitic stainless steel. In some preferred embodiments, the power transmission device comprises a second power transmission member, said second power transmission member spanning the end plate and being electrically and being mechanically connected to the first power transmission member. Preferably, the second power transmission member is rod-shaped. A rod-shape of the second power transmission member has proven advantageous with regards to low electrical resistance while having a relatively small extension perpendicular to the stacking direction, thus reducing the space required to accommodate the second power transmission member in the receiving volume between the base plate and the end plate.

[0025] In some preferred embodiments, the second power transmission member extends through a through-hole formed in the first power transmission member, preferably a through-hole formed in the power transmission tab. This allows a mechanically robust connection of the second power transmission member to the first power transmission member. Preferably, the second power transmission member is held in the through-hole formed in the first power transmission member by a press-fit connection.

[0026] In some preferred embodiments, the second power transmission member is surrounded by a second insulating sleeve formed from an electrically insulating material. Preferably, the second insulating sleeve is configured to electrically insulate the second power transmission member from the end plate. Preferably, the electrically insulating material of the second insulating sleeve comprises or consists of at least one mineral of the mica group, particularly muscovite and / or phlogopite.

[0027] In some preferred embodiments, the electrochemical cell assembly comprises a third support sleeve formed from a ceramic material, said third support sleeve surrounding the second power transmission member and being arranged between the end plate and the first power transmission member. The third support sleeve secures a distance between the first power transmission member, particularly the power transmission tab, and the end plate. An undesired contact between those elements might otherwise result in an electrical short circuit. Preferably, the ceramic material of the third support sleeve comprises or consists of alumina. Preferably, the first power transmission member is biased against the third support sleeve. In case that the above-mentioned second insulating sleeve is provided, the third support sleeve preferably surrounds the second insulating sleeve.

[0028] Preferably, the first support sleeve and the third support sleeve are separated from each other by an empty space. That is to say, preferably no other element is intersected by an imaginary straight line that connects the first support sleeve with the third support sleeve. The empty space between the first support sleeve and the third support sleeve results in a high flexibility regarding the desired deformation of the first power transmission member, particularly of the power transmission tab.

[0029] Preferably, the first support sleeve, the second support sleeve and the third support sleeve are support sleeves of the same type. That is to say, the support sleeves have the same dimensions and are formed from the same material.

[0030] In some preferred embodiments, the electrochemical cell assembly comprises a further power transmission device, wherein the power transmission device, the stack of cell units and the further power transmission device are electrically connected in series in this order. That is to say, the electrochemical cell assembly comprises two power transmission devices. If the electrochemical cell assembly is electrically connected to an external device, one of the power transmission devices can be used as an anode while the other one of the power transmission devices can be used as a cathode.

[0031] Preferably, each of the power transmission devices comprises a connector that is located on the side of the end plate that is facing away from the stack of cell units, each of the power transmission devices spanning the end plate along the stacking direction and being electrically connected to the stack of cell units, and each of the power transmission devices being attached to the end plate by a fastening device at a portion of the power transmission device that is located between an electrical connection of the power transmission device to the stack of cell units and the connector.

[0032] The electrical connection of the stack of cell units with the further power transmission device may be realised in different ways. Preferably, the electrochemical cell assembly comprises an electrically conductive second transmission plate that is allocated to the further power transmission device and arranged between the end plate and the stack of cell units. Said second power transmission plate is electrically connected to the stack of cell units and electrically connected to the further power transmission device. That is to say, the further power transmission device is electrically connected to the stack of cell units by means of the second power transmission plate.

[0033] The first transmission plate and the second transmission plate may be stacked upon one another along the stacking direction and electrically insulated from each other by an interposed insulating plate. That is to say, one of the power transmission plates is located closer to the end plate than the other one of the power transmission plates.

[0034] The electrochemical cell assembly may further comprise an electrically conductive third power transmission plate that is electrically connected to the stack of cell units and located between the stack of cell units and the base plate. The first power transmission plate or the second power transmission plate, preferably the power transmission plate that is located closer to the end plate, may be electrically connected to the third power transmission plate by one or more bus bars spanning the stack of cell units along the stacking direction. That is to say, one of the first and second power transmission plates is electrically connected to the stack of cell units by means of the third power transmission plate and the bus bar or bus bars.

[0035] If an element is provided herein with the additive "first", "second", "third", etc. this is merely to terminologically distinct the element from otherwise equally denominated elements. That is to say, the presence of a "second element" does not necessarily require the presence of a respective "first element". For example, the presence of the above-mentioned "second support sleeve" does not necessarily require the presence of the above-mentioned "first support sleeve".

[0036] Further embodiments are derivable from the following description and the drawings.

[0037] In the drawings: Figure 1 shows a perspective view of a detail of an electrochemical cell assembly;

[0038] Figure 2 shows a cross-sectional view of a detail of the electrochemical cell assembly displayed in Figure 1 in which the cross-sectional plane runs through a power transmission device of the electrochemical cell assembly; and

[0039] Figure 3 shows a cross-secional view of a further detail of the electrochemical cell assembly displayed in Figure 1 in which the cross-sectional plane runs through a further power transmission device of the electrochemical cell assembly.

[0040] Referring to Figures 1 to 3, there is shown an exemplary configuration of an electrochemical cell assembly 10.

[0041] The electrochemical cell assembly 10 comprises a stack 12 having a plurality of cell units 14 that are stacked upon one another along a stacking direction 16. In Figures 2 and 3, only three cell units 14 are visible. The cell units 14 may be fuel cell units, electrolyser cell units or reversible cell units. The cell units 14 extend in a respective cell plane that is perpendicular to the stacking direction 16. The cell units 14 are electrically connected in series. In this example, the cell units 14 are configured flat. An electrical connection between adjacent cell units 14 is established by a direct contact between the cell units 14.

[0042] The stack 12 further comprises gaskets 18 that are interposed between adjacent the cell units 14. Exemplarily, the gaskets 18 are configured as annular sealing rings having a central opening 20. The gaskets 18 surround respective fluid ports 22 of the cell units 14.

[0043] The electrochemical cell assembly 10 further comprises an end plate assembly 24 having an end plate 26 and a base plate assembly having a base plate. The base plate assembly and base plate are not visible in Figures 1 to 3. The stack 12 is arranged between the end plate 26 and the base plate. That is to say, the end plate 26 and the base plate are arranged on opposite sides of the stack 12 and the stack 12 is arranged in a receiving volume defined between the end plate 26 and the base plate. Preferably, the stack 12 is held in compression between the end plate 26 and the base plate. This improves the sealing effect of the gaskets 18.

[0044] With reference to Figure 1 , the electrochemical cell assembly 10 further comprises a housing 28 that surrounds the stack 12. Preferably, the housing 28 is fixedly attached to the end plate 26 and the base plate, e.g. by welding.

[0045] In this example, the electrochemical cell assembly 10 further comprises an electrically conductive first power transmission plate 30 that is located between the stack 12 of cell units 14 and the end plate 26. The first power transmission plate 30 is electrically connected to the stack 12, i.e. to the cell units 14. Electrical connection is provided by a direct contact between the first power transmission plate 30 and the uppermost cell unit 14, i.e. the cell unit 14 that is located closest to the end plate 26.

[0046] In this example, the electrochemical cell assembly 10 further comprises an electrically conductive second power transmission plate 32 that is located between the first power transmission plate 30 and the end plate 26. The second power transmission plate 32 is electrically connected to the stack 12, i.e. to the cell units 14. This electrical connection is provided by means of an electrically conductive third power transmission plate that is not visible in the figures. The third power transmission plate is located between the stack 12 of cell units 14 and the base plate. Electrical connection between the third power transmission plate and the cell units 14 is provided by a direct contact between the third power transmission plate and the lowermost cell unit 14, i.e. the cell unit 14 that is located closest to the base plate. The electrical connection between the second power transmission plate 32 and the third power transmission plate may be provided by one or more bus bars that span the stack 12 of cell units 14 along the stacking direction 16.

[0047] The first power transmission plate 30 is electrically insulated from the second power transmission plate 32 by an interposed first insulating plate 34. The second power transmission plate 32 is electrically insulated from the end plate 26 by an interposed second insulating plate 36. Preferably, the insulating plates 34 and 36 are formed from an insulating material that comprises or consists of at least one mica group mineral, particularly muscovite and / or phlogopite. The electrochemical cell assembly 10 further comprises an electrically conductive power transmission device 38. The power transmission device 38 comprises a connector 40 that is located on a side of the end plate 26 that is facing away from the stack 12 of cell units 14. That is to say, the end plate 26 is located between the connector 40 and the stack 12 of cell units 14.

[0048] The power transmission device 38 spans the end plate 26 along the stacking direction 16 and is electrically connected to the stack 12 of cell units 14. In this example, the power transmission device 38 is electrically connected to the stack 12 of cell units 14 by means of the first power transmission plate 30.

[0049] The power transmission device 38 is attached to the end plate 26 by a fastening device 42 at a portion of the power transmission device 38 that is located between an electrical connection of the power transmission device 38 to the stack 12 of cell units 14 and the connector 40. During electrical connection of the connector 40 to an external device, e.g. an electrical energy storage device, push forces, pull forces and torques may be applied to the connector 40. Due to the above-described attachment of the power transmission device 38 to the end plate 26, said forces will be transmitted to the end plate 26. Thus, the stack 12 of cell units 14 is protected or decoupled from the forces.

[0050] In this example, the power transmission device 38 comprises a first power transmission member 44 that is located on the side of the end plate 26 that is facing away from the stack 12 of cell units 14. Said first power transmission member 44 is attached to the end plate 26 by the fastening device 40. That is to say, the above-mentioned portion of the power transmission device 38 is a portion of the first power transmission member 44.

[0051] The first power transmission member 44 is configured as a deformable power transmission tab 46. The power transmission tab 46 comprises a deformation section 48 that is arranged in parallel with the end plate 26.

[0052] In this example, the power transmission tab 46 has a thickness of 1.2 mm. Due to this thickness, the power transmission tab 46, particularly the deformation section 48, can easily be deformed in order to compensate for a thermal expansion of elements of the electrochemical cell assembly 10 along the stacking direction 16. The power transmission tab 46 further has a width that is distinctly larger than its thickness, preferably a width of at least 1.0 cm. Due to this width, the electrical resistance value of the power transmission tab 46 is relatively low.

[0053] The power transmission tab 46 further comprises a folded edge 50 that extends perpendicularly to the deformation section 48 and to the end plate 26. The connector 40 of the power transmission device 38 is provided by said folded edge 50.

[0054] The fastening device 42 comprises a fastening member 52, in the present example a screw, that extends through a through-hole 54 that is formed in the deformation section 48 of the power transmission tab 46 and into a threaded recess of the end plate 26.

[0055] The power transmission device 38 further comprises a rod-shaped second power transmission member 56 that is electrically and mechanically connected to the first power transmission member 44, i.e. the power transmission tab 46. In this example, the second power transmission member 56 extends through a through- hole 58 formed in the first power transmission member 44. The second power transmission member 56 spans the end plate 26. In this example, the second power transmission member 56 extends through a through-hole 60 that is formed in the end plate 26.

[0056] The second power transmission member 56 is electrically connected to the first power transmission plate 30. That is to say, the second power transmission member 56 and thus the power transmission device 38 is electrically connected to the stack 12 of cell units 14 by means of the first power transmission plate 30. In this example, the rod-shaped second power transmission member 56 ends on a surface of the first power transmission plate 30 that is facing towards the end plate 26 and away from the stack 12 of cell units 14.

[0057] The fastening member 52 is surrounded by a first insulating sleeve 62 that is formed from an electrically insulating material, preferably from an insulating material that comprises or consists of at least one mica group mineral. The fastening member 52 is electrically insulated from the first power transmission member 44 by the first insulating sleeve 62.

[0058] The fastening member 52 and the first insulating sleeve 62 are surrounded by a first support sleeve 64 that is formed from a ceramic material, preferably from a ceramic material that comprises or consists of alumina. The first support sleeve 64 is located between the end plate 26 and the first power transmission member 44. Thus, the first support sleeve 64 secures a distance between the end plate 26 and the first power transmission member 44.

[0059] The fastening member 52 and the first insulating sleeve 62 are further surrounded by a second support sleeve 66 that is formed from a ceramic material, preferably from a ceramic material that comprises or consists of alumina. The second support sleeve 66 is located between the first power transmission member 44 and a stop provided by a head of the fastening member 52. In this example, a washer 68 is located between the second support sleeve 66 and the head of the fastening member 52.

[0060] The fastening member 52 is preferably formed from a material that has a coefficient of thermal expansion that is higher than the coefficient of thermal expansion of the ceramic material of the support sleeves 64 and 66. Preferably, the fastening member 52 is formed from austenitic stainless steel. In use, the elements of the electrochemical cell assembly 10 may reach temperatures of 500 °C and above, resulting in a pronounced thermal expansion of the elements of the electrochemical cell assembly 10 along the stacking direction 16. Due to the material of the fastening member 52, i.e. due to the coefficient of thermal expansion, the fastening member 52 will expand during use more than the support sleeves 64 and 66, resulting in the attachment of the power transmission device 38 to the end plate 26 being slightly loosened. As a consequence, the power transmission device 38 is slightly movable with respect to the end plate 26 and can compensate for thermal expansion of elements of the electrochemical cell assembly 10.

[0061] The second power transmission member 56 is surrounded by a second insulating sleeve 70 that is formed from an electrically insulating material, preferably from an insulating material that comprises or consists of at least one mica group mineral. The second power transmission member 56 is electrically insulated from at least the end plate 26 by the second insulating sleeve 70.

[0062] The second power transmission member 56 and the second insulating sleeve 70 are surrounded by a third support sleeve 72 that is formed from a ceramic material, preferably from a ceramic material that comprises or consists of alumina. The third support sleeve 72 is located between the first power transmission member 44 and the end plate 26. Thus, the third support sleeve 72 secures a distance between the end plate 26 and the first power transmission member 44.

[0063] The second power transmission member 56 and the second insulating sleeve 70 are surrounded by a fourth support sleeve 74 that is formed from a ceramic material, preferably from a ceramic material that comprises or consists of alumina. The fourth support sleeve 74 is located between the end plate 26 and the second power transmission plate 32, in a through-hole formed in the second insulating plate 36. A respective gasket 18 is arranged on both end faces of the fourth support sleeve 74.

[0064] The second power transmission member 56 and the second insulating sleeve 72 are surrounded by a fifth support sleeve 76 that is formed from a ceramic material, preferably from a ceramic material that comprises or consists of alumina. The fifth support sleeve 76 is located between first power transmission plate 30 and the second power transmission plate 32, in a through-hole formed in the first insulating plate 34. A respective gasket 18 is arranged on both end faces of the fifth support sleeve 76.

[0065] In this example, the support sleeves 64, 66, 72, 74 and 76 are support sleeves of the same type. That is to say, the support sleeves 64, 66, 72, 74 and 76 have the same dimensions and are formed from the same material.

[0066] The electrochemical cell assembly 10 further comprises a further power transmission device 38a that is attached to the end plate 26 by a further fastening device 42a (see Figure 3). The configuration of the power transmission device 38 and the further power transmission device 38a are essentially identical. The same amounts for the fastening device 42 and the further fastening device 42a. For this reason, regarding the configuration of the further power transmission device 38 and the further fastening device 42a, reference is made to the abovedescribed configuration of the power transmission device 38 and the fastening device 42.

[0067] The further power transmission device 38a differs from the power transmission device 38 in that the further power transmission device 38a is electrically connected with the second power transmission plate 32. In this example, a rodshaped second power transmission member 56a of the further power transmission device 38a ends on a surface of the second power transmission plate 32 that is facing towards the end plate 26 and away from the stack 12 of cell units 14.

[0068] In view of the above-described configuration, the power transmission device 38, the stack 12 of cell units 14 and the further power transmission device 38a are electrically connected in series in this order. As a consequence, when electrically connecting the electrochemical cell assembly 10 to an external device, e.g. an electrical energy storage device, one of the power transmission devices 38, 38a can be used as an anode while the other one of the power transmission devices 38, 38a can be used as a cathode.

Claims

Claims1. An electrochemical cell assembly (10), comprising a base plate assembly having a base plate, an end plate assembly (24) having an end plate (26), a stack (12) of cell units (14), comprising a plurality of cell units (14) stacked upon one another along a stacking direction (16), said stack (12) of cell units (14) being arranged between said base plate and said end plate (26), and an electrically conductive power transmission device (38) comprising a connector (40) that is located on a side of the end plate (26) that is facing away from the stack (12) of cell units (14), the power transmission device (38) spanning the end plate (26) along the stacking direction (16) and being electrically connected to the stack (12) of cell units (14), wherein the power transmission device (38) is attached to the end plate (26) by a fastening device (42) at a portion of the power transmission device (38) that is located between an electrical connection to the stack (12) of cell units (14) and the connector (40).

2. The electrochemical cell assembly (10) according to the preceding claim, wherein the power transmission device (38) comprises a first power transmission member (44) that is located on the side of the end plate (26) that is facing away from the stack (12) of cell units (14), said first power transmission member (44) being attached to the end plate (26) by the fastening device (42).

3. The electrochemical cell assembly (10) according to the preceding claim, wherein the first power transmission member (44) is configured as a deformable power transmission tab (46) .

4. The electrochemical cell assembly (10) according to the preceding claim, wherein the power transmission tab (46) comprises a deformation section (48) that is arranged in parallel with the end plate (26).

5. The electrochemical cell assembly (10) according to any one of claims 3 and4, wherein the power transmission tab (46) has a thickness of at most 3.0 mm, preferably at most 2.0 mm, most preferably at least 0.5 mm and at most 2.0 mm.

6. The electrochemical cell assembly (10) according to any one of claims 3 to5, wherein the power transmission tab (46) has a width of at least 1.0 cm, preferably at least 2.0 cm.

7. The electrochemical cell assembly (10) according to any one of claims 3 to6, wherein the connector (40) is formed by a folded edge (50) of the power transmission tab (46).

8. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein said fastening device (42) comprises a fastening member (52) extending through a through-hole (54) formed in the power transmission device (38) and into a recess formed in the end plate (26).

9. The electrochemical cell assembly (10) according to any one of claims 7 and8, wherein the fastening member (52) is surrounded by a first insulating sleeve (62) formed from an electrically insulating material, said first insulating sleeve (62) electrically insulating the fastening member (52) from the power transmission device (38).

10. The electrochemical cell assembly (10) according to any one of claims 7 to9, wherein the electrochemical cell assembly (10) comprises a first support sleeve (64) formed from a ceramic material, said first support sleeve (64) surrounding the fastening member (52) and being arranged between the end plate (26) and the power transmission device (38).

11. The electrochemical cell assembly (10) according to any one of claims 7 to10, wherein the cell assembly (10) comprises a second support sleeve (66) formed from a ceramic material, said second support sleeve (66) surrounding the fastening member (52) and being arranged between thepower transmission device (38) and a stop provided by a head of the fastening member (52).

12. The electrochemical cell assembly (10) according to any one of claims 10 and 11 , wherein the coefficient of thermal expansion of the material of the fastening member (52) is higher than the coefficient of thermal expansion of the ceramic material of the first support sleeve (64), preferably by at least 2*1 O'6K'1, and / or wherein the coefficient of thermal expansion of the material of the fastening member (52) is higher than the coefficient of thermal expansion of the ceramic material of the second support sleeve (66), preferably by at least 2*10'6K'1.

13. The electrochemical cell assembly (10) according to any one of claims 2 to 12, wherein the power transmission device (38) comprises a, preferably rodshaped, second power transmission member (56), said second power transmission member (56) spanning the end plate (26) and being electrically and mechanically connected to the first power transmission member (44).

14. The electrochemical cell assembly (10) according to the preceding claim, wherein the second power transmission member (56) extends through a through-hole (58) formed in the first power transmission member (44).

15. The electrochemical cell assembly (10) according to the any one of claims 13 and 14, wherein the second power transmission member (56) is surrounded by a second insulating sleeve (70) formed from an electrically insulating material, said second insulating sleeve (70) electrically insulating the second power transmission member (56) from the end plate (26).

16. The electrochemical cell assembly (10) according to any one of claims 13 to 15, wherein the electrochemical cell assembly (10) comprises a third support sleeve (72) formed from a ceramic material, said third support sleeve (72) surrounding the second power transmission member (56) and being arranged between the end plate (26) and the first power transmission member (44).

17. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the electrochemical cell assembly (10) comprises a further power transmission device (38a), and wherein the powertransmission device (38), the stack (12) of cell units (14) and the further power transmission device (38a) are electrically connected in series in this order.

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