SE2250245A1

SE2250245A1 - Battery assembly with nanowires

Info

Publication number: SE2250245A1
Application number: SE2250245A
Authority: SE
Inventors: Csaba Dobi; Daniela Bok; Mirko Stadel; Rodyn Gilharry
Original assignee: Northvolt Ab
Priority date: 2022-02-23
Filing date: 2022-02-23
Publication date: 2023-08-24
Also published as: WO2023161309A1

Abstract

ABSTRACT An electrode plate assembly for a secondary battery module is disclosed, comprising a plurality of cells (100) arranged in a vertical stack (10). Each cell of the stack comprises a positive electrode plate (110) and a negative electrode plate. The cell is configured allow ions to move between the positive electrode plate and the negative electrode plate. A first cell (602) of the stack and a neighboring, second cell (603) of the stack are joined by a plurality of nanowires (601) configured to electrically connect a first contact surface (604) of the first cell to a second contact surface (605) of the second cell.

Description

BATTERY ASSEMBLY WITH NANOWIRES Background Rechargeable or secondary batteries find widespread use as electrical power supplies and energy storage systems. For example, in automobiles, battery packs formed of a plurality of battery modules, wherein each battery module includes a plurality of electrochemical cells, are provided as a means of effective utilization of electric power, also in the viewpoint of air pollution prevention. Several different form factors exist for the electrochemical cells applied in secondary batteries depending on their intended application field. ln automotive applications, the most common cell types are cylindrical, prismatic and pouch cells. A further concept for automotive applications is large format flat, thin cells, which in general include a single positive electrode and a single negative electrode and in which the upper and lower surfaces are formed by the electrodes, which serve as cell housing and also act as the terminals for the cell. However, there is still a need for alternative and improved cell designs and battery packs, in particular in view of electrical monitoring of the cells and challenges relating to mechanical movement during cell swelling.

Description of the inventive concept According to a first aspect, a secondary battery module, or battery pack, comprising a plurality of cells arranged in a vertical stack is provided. Each of the cells of the stack comprises a positive electrode plate (also referred to as a positive electrode), a negative electrode plate (also referred to as a negative electrode) and a separator interposed between the positive electrode plate and the negative electrode plate. The separator is configured to allow ions to move between the positive electrode and the negative electrode. Thus, the positive electrode, the negative electrode and the separator may be arranged in a single positive electrode-separator-single negative electrode stack.

According to some embodiments the cells may be serially stacked on top of each other, such that the electrodes of two neighbouring cells are brought in electrical contact with each other. The electrical contact may for instance be achieved by a direct mechanical contact between adjacent cells, in which the bottom electrode of the upper cell is abutting the upper electrode of the lower cell. Alternatively, or additionally an intermediate layer may be provided between the cells to facilitate mechanical and/or electrical contact between the cells. The intermediate layer may for example comprise an electrically conductive adhesive.

According to some embodiments the positive electrode (that is, the cathode) may include a first foil substrate, which may be formed of a first electrically-conducive material, and a first active material layer disposed on an inward facing side of the first foil substrate (that is, a side facing the separator and the negative electrode of the cell). The first foil substrate may preferably be a metal foil substrate formed of a first electrically conductive material such as aluminium, without being limited thereto. The first active material layer preferably comprises a first active material selected from a lithiated metal oxide, and in particularfrom a lithium transition metal composite oxide, wherein the metal preferably includes one or more of nickel (Ni), cobalt (Co) and manganese (Mn). According to a preferred example, the positive electrode is formed of an aluminium foil and has an active material layer comprising a lithium transition metal composite oxide disposed on the inward facing side. ln embodiments, the first electrically conductive material of the first foil substrate may be coated on one or both sides thereof with an oxidation-preventing metal, such as chromium. ln further embodiments, a conductive material layer may additionally be disposed on an inward facing side of the first foil substrate, such that the conductive material layer is sandwiched between the first foil substrate and the first active material layer in order to enhance cell performance.

According to some embodiments the negative electrode (that is, the anode) may include a second foil substrate, which may be formed of a second electrically conducive material and a second active material layer disposed on an inward facing side thereof (that is, a side facing the separator and the positive electrode in the cell). The second foil substrate may preferably be a metal foil substrate formed of a second electrically conducive material such as copper or copper-clad aluminium, without being limited thereto. The second active material layer preferably comprises a second active material selected from graphite or silicon, or mixtures thereof. According to a preferred example, the negative electrode may be formed of a copper foil and has an active material layer comprising graphite disposed on the inward facing side. ln embodiments, the second electrically conducive material of the second foil substrate can be coated on one or both sides thereof with an oxidation-preventing metal, such as chromium.

The outward facing sides of first and second foil substrates of the respective electrodes can act as the negative and positive cell terminals, respectively, and may be electrically and mechanically connected in series to neighbouring cells in the cells stack.

The positive and negative electrodes may be spaced apart from each other by the separator, which may comprise an electrically isolating and permeable material that isolates the positive electrode from the negative electrode to prevent electrical short-circuiting and allow ion, provided in an electrolyte, to pass therethrough. ln an example, the separator may comprise a three-layer structure comprising for example a base film, including a polyolefin and a non-woven material, a ceramic layer coated on the base film, and a layer including polyvinylidenfluorid and acrylate binder coated on the ceramic layer. The separator may have a peripheral shape that conforms to the peripheral shape of the positive electrode and the negative electrode. Further, the separator may in some embodiments have the same dimensions as the positive and negative electrodes. ln addition, a sealing layer may be provided between a peripheral edge of the separator and a peripheral edge of the positive electrode. A sealing layer may further be disposed between a peripheral edge of the separator and a peripheral edge of the negative electrode. The sealing layer may be provided to prevent short-circuiting between the electrodes, bond the electrodes to each other and prevent any liquid electrolyte from escaping the cell. ln some embodiments, the separator has lesser dimensions than the dimensions of the positive electrode and the negative electrode so that a peripheral edge of the separator resides within peripheral edges of the positive and negative electrodes when the cell is view in a top plan view. A sea|ing layer may be provided between a peripheral edge of the positive electrode and a peripheral edge of the negative electrode such that the positive electrode is sea|ed to the negative electrode, and the sea|ing layer surrounds a periphery of the separator.

The present electrode plate assembly provides a relatively large format flat cell in which the top and bottom surfaces, facing away from the separator, may act as positive and negative terminals. This allows for the cells to be stacked serially, eliminating the need for busbars of complex terminal attachments between the cells. By arranging the cells in direct contact with each other, or indirect via an electrically conducting intermediate layer, a relatively large contact area can be utilised to reduce electrical resistance between the series connected cells.

According to a second aspect, the electrode plate assembly may comprise a plurality of contacting means for electrical monitoring of the cells. Each of the contacting means may be electrically connected to at least one of the positive and negative electrode plates of a respective one of the cells and arrange to protrude laterally from a side edge of the cell. The contacting means may be distributed spatially along a width of the stack to facilitate physical an electrical access to the contacting means, as will be discussed in further detail in the following.

The contacting means may be substantially plate shaped and may be understood as a ﬂap or strip of electrically conductive material attached to or projecting from an electrode. The contacting means may also be referred to as a tab, or voltage pickup tab. The tabs may be attached to a peripheral portion of the electrode, for instance by welding, soldering or conductive adhesive, or formed from a portion of the electrode. Thus, the electrode plate may in some embodiments be cut, or formed into a shape allowing a protruding portion of the electrode to function as a contacting means.

Figure 1a is a top view of a single cell 100 according to an embodiment. The cell 100 comprises a positive electrode plate 110 arranged in a stack with a negative electrode plate 120 and a separator 130 (not shown), similar to what is described above in connection with the first aspect. A contacting means 140 is provided at a side edge 101 of the cell 100. ln the present example, the contacting means 140 is electrically connected to the positive electrode plate 110 and arranged a first position along the side edge 102. As illustrated in the present figure, the contacting means 140 may be formed as a substantially plate shape, or tab shaped, element oriented in a plane parallel to the electrode plate 110 and protruding laterally from the side edge 102 to allow the contacting means 140 to be physically and electrically accessed.

The contacting means 140 may comprise a main portion 142 protruding from the cell 100, and a contacting portion 144 attached to the main portion 142 and configured to facilitate electrical access by e.g. a battery management system.

The contacting means 140 may be distributed spatially along a width W of the stack, as illustrated in figure 1b. Figure 1b shows a vertical stack 10 of a plurality of cells 100, wherein a contacting means 140, such as a voltage pickup tab 140, is attached to each (or at least some) of the cells 100. The contacting means 140 may hence be arranged to protrude from the side edge 101 of the cells 100 at different positions along the width direction W. This allows for each of the contacting means 100 to be accessed from the side 101 of the cells 100 in a relatively easy manner also when a plurality of cells 100, such as 24 as shown in the present figures, are stacked on top of each other. ln the present example, the contacting means 140 may be considered to be staggered with respect to each other along the vertical direction. ln different words, the contacting means 140 of adjacent cells in the stack may be arranged so that they are not in line along the vertical direction.

Figure 1c shows a further example, in which 216 cells 100 are stacked in sets of 24, and wherein each set may be rotated by 0°, 90° and 180°, respectively. Each set of 24 may be similar to the stack disclosed in figure 1b and may hence comprise contacting means 140 that are substantially evenly distributed along the width direction W1. By rotating the sets 0°, 90° and 180° the contacting means 140 may be distributed over three side edges 101, 102, 103 of the stack. This allows for the contacting means 140 to be distributed over the width W1, W2, W3 of each side edges, as well as in the stacking direction, as indicated in figure 1d.

Figure 1d is a cross section of a portion of the stack in figure 1c, showing vertically aligned contacting means 140 from three different sets of cells that are stacked on top of each other.

Figure 1e illustrates an example of the distribution of contacting means 140 over the side edges 101, 102, 103 of an electrode plate 110. The contacting means 140 may be formed by an integral portion of the electrode plate 110, such as a portion of the foil substrate not covered with any active material layer, or by a separate contacting member which has been attached to a contacting portion of the electrode plate 110. As illustrated in the present figures, a plurality of positions n for the contacting means 140 may be defined along the width of the side edges 101, 102, 103. The positions n, in which the contacting means 140 may be arranged, are indicated by dotted lines in the present figure, whereas the actual contacting means 140 is indicated by a full line. The positions n may thus be considered to represent different available "slots" for the contacting means 140, which may varied in the stack in order to ensure a spatial distribution of the of the contacting means 140 along the sides of the stack. A first one of the cells may for instance comprise a contacting means 140 arranged at position n1, whereas the adjacent or neighbouring cell of the stack may comprise a contacting means 140 arranged at position n2, etcetera. ln the present example, there are 15 positions available at the first side 101, 10 positions available at the second side 102 and 15 positions available at the third side 103 of the stack. This means that the stack may comprise 45 consecutive cells, of which each may have a contacting means 140 arranged at a unique position n along the side edges 101, 102, 103. This may be understood as the 45 contacting means 140 being staggered in the vertical direction. The 46"' cell of the stack, arranged adjacent to the 45th cell, may have a contacting means 140 arranged at the first position n1. The contacting means 140 of the 46"' cell may hence be vertically aligned with the Contacting means 140 of the first cell of the stack but separated in the vertical direction by the 45 layers of intermediate cells. The contacting means 140 of the first cell and the 46"' cell may therefore be considered as distributed in the vertical direction, thereby facilitating individual access to the respective contacting means 140.

Figure 1f illustrates an example wherein the contacting means 140 is formed of a portion of the electrode plate 110. Hence, as referred to above, the tab 140 may be formed directly from the metal foil 110, preferably as the metal foil 110 is cut or othenNise given its final shape. This advantageously allows for a reduction in the number of steps required for the assembly process, since there is no need for additional steps of attaching or soldering contacting means, formed of separate elements, onto the electrode plate 110. lt will be appreciated that the above-disclosed configurations are merely exemplary embodiments illustrating a possible implementation of the inventive concept. Other configurations and distributions of the contacting means 140 are however conceivable. Further, it will be appreciated that each of the cells may not necessarily be connected to a respective contacting means 140. On the contrary, the contacting means may in some embodiments be connected to a subset of cells, such as to every second or third cell of the stack.

According to some embodiments, the electrode plate assembly may comprise access points instead of the contacting means as discussed above with reference to figures 1a-f. The access points may be distributed in a similar way as the above-mentioned contacting means, that is, spatially along a width (and/or stacking direction) of the stack. The access points may however differ from the contacting means in that they are formed by regions or portions of the positive or negative electrode, or any intermediate structure attached to the positive or negative electrode.

According to some embodiments, the electrode plate assembly may comprise a plurality of sensors configured to be coupled to a respective contacting means or access point. The sensor may for example be connected to the access point by means of an electrical lead, by a contacting means, or be attached directly to the electrode.

The electrode plate assembly may further comprise a plurality of wireless transmitters, wherein each of the transmitters is configured to receive a signal from one or several of the sensors and transmit the signal to an external receiver. The sensor may be configured to generate a signal that is indicative of an operation parameter of one or several cells of the stack. The operational parameter may for example relate to a current, voltage or temperature of the cell.

According to an embodiment, the electrode plate assembly, or battery pack, may comprise a side frame part configured to be arranged at a side of the stack. The side frame part may comprise a plurality of slots, wherein each of the slots may be configured to receive a respective contacting means as the side frame part is being arranged at the side of the stack. The side frame part may form a part of a modular side frame assembly, comprising two or more parts which can be assembled into a frame at least partly enclosing the sides of the stack.

Figure 2a illustrates an example of a side frame part 210, configured to be arranged at a side of the stack and fitted with further frame parts to form a casing or frame enclosing the sides of the stack. The side frame part 210 may comprise a mechanically stabilising first part 212 and a second part 214 for providing electrical connection of the protruding contacting means 140. The second part 214 may for example be a printed circuit board, PCB, comprising contact pads 216 to which the contacting means 140 may be mounted, for example by soldering, welding or electrically conductive adhesive. The mechanically stabilising first part 212 may be arranged between the stack and the second part 214, and the contact pads 216 may be arranged on a side of the second part 214 facing away from the stack. lt will however be appreciated that the configuration in figure 2a is merely an example, and that the side frame part 210 may be configured differently. For example, the side frame part 210 need not necessarily comprise the first part 212 and the second part 214. lnstead, the side frame part 210 may as well be formed from a single piece, having contact pads 216 or contact points 216 to which the contacting means 140 may be attached. . ,,. 0,: As illustrated in the present figure, the side frame part 210 may comprise a plurality of slits, or through-holes 215, configured to receive a respective Contacting means 140 as the side frame part 210 is being arranged at the side of the stack. Thus, the slits 215 may have a shape corresponding to a cross sectional shape of the contacting means 140 to allow the contacting means 140 to extend through the side frame part 210 and be attached to the outer side of the side frame 210, i.e., the side of the side frame facing away from the stack. The slits 215 may hence be distributed spatially along a length direction of the side frame part 210 in a similar way as the contacting means 140 are distributed over the side of the stack.

The contacting means 140, or tabs 140, may be arranged to extend through the slits 215 and then be folded to contact the contact points, or contact pads 216, of the side frame part 210. Figure 2a illustrates a tab both in its unfolded state, in which it is oriented in a plane parallel to the main plane of extension of the electrodes, and in a folded state in which it abuts the contact point 216 of the side frame part 210.

The slits 215 may be slightly larger than the cross section of the corresponding contacting means 140, extending therethrough, to provide some margin or tolerance for a relative movement between the contacting means 140 and the side frame part 210. The tolerance may facilitate the assembly process, reducing the requirements on alignment precision. Further, the tolerance may be introduced to address relative movement during operation of the battery pack. ln particular, the height of the slits 215 (as measured along the stacking direction) may be larger than a thickness of the contacting means 140 to allow the contacting means to move along the stacking direction during swelling of the cells.

Figure 2b is a cross section of a portion of the stack 10, showing a side frame part 210 arranged at the side of the stack 10 such that the contacting means 140 protrude through the side frame part 210. The side frame part 210 may for example be formed of a plastic material and may in some examples comprise a PCB (not shown) attached to the side of the side frame part 210 facing away from the stack 10. The side frame part 210 may be attached to the stack 10 by means of fastening pins 218 engaging a support fixture, or base plate 220 arranged below the stack 10. The side frame part 210 further be snap-fitted to further side frame parts 210 arranged at other sides of the stack to form a casing or frame enclosing the stack 10. The other side frame parts may be configured to electrically connect contacting means 140 protruding from the sides of the stack, or comprise terminal means for electrical connection of the battery pack. Further, it will be appreciated that the side frame parts may comprise further electronic components relating to e.g. monitoring of the battery cells and transmission of information associated with a status or performance of the cells. Thus, the side frame, which may be referred to as a modular side frame due to the interlocking character of the individual side frame parts, may be provide both mechanical support and protection of the stack 10, as well as monitoring and communication capabilities.

Figure 2c schematically illustrate that compressive forces F may be applied to the stack in the stacking direction during the assembly process to compress the cells and thereby allow the contacting means, or tabs 140, to be arranged at their nominal positions (in the stacking direction) before they are attached to the contact points 216 on the frame parts. Put differently, the stack may be compressed in the stacking direction to align the contacting means 140 vertically prior to welding.

A plurality of cells arranged in a vertical stack, such as the stack described above with reference to the first and second aspect, may be subject to expansion due to cell swelling. As multiple cells are stacked to increase voltage, the cell swelling over the stack may result in a relatively large mechanical movement or expansion in the stacking direction. The swelling may be challenging for the designers of the battery pack, as the swelling may cause problems relating to the electrical as well as mechanical performance of the battery pack, as will be exemplified in the following.

According to a third aspect, an electrode plate assembly for a secondary battery module is provided, comprising a plurality of cells arranged in a vertical stack. The stack may be similarly configured as the stack discussed above in connection with the first and second aspect. Hence, each of the cells of the stack comprises a positive electrode plate, a negative electrode plate and a separator, wherein the separator is interposed between the positive electrode plate and the negative electrode plate and configured to allow ions to move between the positive and negative electrode plate.

Further, neighbouring or adjacent cells of the stack are arranged such that the positive electrode plate of a first one of the neighbouring cells is contacting the negative electrode plate of the other one of the neighbouring cells, thereby allowing for the cells of the stack to be series connected along the stacking direction.

According to the present aspect, the electrode plate assembly may further comprise a top terminal plate, which is arranged above the stack and in electrical contact with a top one of the cells, a bottom terminal plate arrange below the stack and in electrical contact with a bottom one of the cells, and a housing configured to accommodate the bottom terminal plate, the stack, and the top terminal. The housing comprises a base plate and a top cover configured to be attached to each other to form the housing. Further, an elastic means may be arranged between the top cover and the top terminal to exert a compressing force on the stack in the stacking directions.

A merit of the present aspect is that the housing may allow for an improved cooling of the stack. The improved cooling may be achieved at least partly due to the relatively large surface-to-volume of the housing, facilitating heat dissipation from outer surfaces of the housing.

An example of such a housing is disclosed in figure 3a, formed by a base plate 314 and a top cover 312. The base plate 314 and the top cover 312 may be configured to be assembled into the housing, wherein the base plate 314 in the present example forms a bottom and two of the sidewalls of the housing, and the top cover 312 forms the top and the remaining sidewalls of the housing. The top cover 312 may be mechanically attached and sealed to the base plate by means of a rim portion extending along the periphery of the base plate and top cover, respectively. The attachment may for example be achieved by means of rivets. Preferably, the base plate 314 is relatively rigid and form stable to provide mechanical support to the stack and reduce the risk of deformation of the stack.

Figure 3a further illustrates a bottom terminal plate 323, which may be configured to be arranged below the stack (not shown in figure 3a), and a top terminal plate 321 configured to be arrange above the stack. The terminal plates 321, 323 may have a similar shape as the electrodes plates of the cells to provide a relatively large contact area and to distribute any contacting forces over an as large area of the cells as possible. Each of the terminal plates 321, 323 may further comprise a respective terminal contact 322, 324, or busbar, which may be configured to be arranged at one of the sides of the stack.

The battery pack of figure 3a may also comprise a frame structure assembled from a plurality of side frame parts 210, which may be similarly configured as the side frame parts 210 discussed above with reference to e.g. figures 2a-c. ln the present example, three of the side frame parts 210 may be configured to receive the tab-shaped contacting means 140, whereas the fourth one of the side frame parts 210 may be configured to receive or support, inter alia, the terminal contacts 322, 324. The frame structure may thus provide both mechanical support of the stack as well as electrical access to the cells for battery monitoring functions.

As will be discussed in further detail below, the top terminal contact 322 may be connected to the top terminal plate 321 by means of a ﬂexible busbar allowing the top terminal plate to move relative to the side frame part, to which the terminal contact 322 is attached.

The battery pack may further comprise an elastic means 330 configured to be arranged between the top cover 312 and the top terminal plate 321. The elastic means 330 may be biased between the top cover 312 and the top terminal plate 321 in order to exert a compressing force on the stack, along the stacking direction. The compressing force may be provided to improve the electrical contact between the series connected cells. Further, since the elastic means 330 is elastic, it is capable of maintaining a compressive force on the stack also during swelling and shrinking of the stack. Put differently, the elastic means 330 is configured to deform as the top terminal plate moves along the stacking direction, thereby absorbing the movement while maintaining a compression of the stack.

R -. 'våi The elastic means 330 may be substantially plate-shaped, having a shape and size corresponding to the lateral size and shape of the stack to allow a substantially uniform load distribution over the cells. The elastic means 330 may thus be referred to as a compression plate and may for instance comprise a spring plate as illustrated in figure 3a or a pad of an elastic material, such as a foam pad.

Figure 3b shows two different examples of compression plates, wherein the first one is a foam pad 331, such as a silicone foam pad, and the second one is a spring plate 332 comprising two parallel plates that are joined to each other by means of a plurality of spring elements. By any of these arrangements the cell stack may be biased in the stacking direction to ensure compression of the cells also when there is a movement or swelling in the stacking direction. Thus, a relatively constant and even compression, or contact pressure between adjacent cells may be achieved as the stack expands and contracts along the stacking direction. Further, the compression allows for any intermediate layers, such as cell sealants and conductive adhesives between adjacent cells, to be relatively evenly distributed or spread over the contact surfaces. Especially during assembly when a compressing force may be applied to spread the intermediate layer. The present aspect therefore has the merits of maintaining a compression of the stack also when there is a relatively large mechanical movement or expansion in the stacking direction.

According to a fourth aspect, an electrode plate assembly is provided, which may be similarly configured as the electrode plate assembly according to the first aspect, with the addition of a top terminal plate arranged above the stack and in electrical contact with a top one of the cells, a top terminal contact, and a flexible busbar arranged to electrically connect the top terminal plate. The flexible busbar is further configured to allow the top terminal plate to move relative the top terminal contact in response to the stack moving, or expanding and contracting, in the stacking direction. The terminal plates, the terminal contacts and the flexible busbar may be similarly configured as the embodiments discussed above with reference to figure 3a. The present aspect hence aims at addressing challenges associated electrical contact of the stack as the stack is subject to swelling.

Further, it will be appreciated that the terminal plates and/or the busbar may serve the additional purpose of dissipating heat from the electrode plate assembly. Thus, the present aspect is advantageous in that is may allow for an improved cooling of the stack.

Figure 4 is a perspective view of a portion of a battery pack according to some embodiments. The battery pack comprises a cell stack arranged between a top terminal plate 321 and a bottom terminal plate (not shown) and at least partly enclosed at the sides by a frame structure 210 comprising electrical access points for any contacting means 140 as discussed in connection with figures 1a-f and 2a-c. The contacting means 140 are connected at a first side of the stack, whereas the top terminal contact 322 and the bottom terminal contact 324 are supported by the side frame 210 at a second side of the stack. Thus, in some examples, three of the sides of the frame 210 may be configured to receive the tab-shaped contacting means 140, whereas the fourth side of the frame 210 may be configured to receive or support, inter alia, the terminal contacts 322, 324. lt will however be appreciated that other configurations, shapes and designs are possible. For example, the cell stack (and hence the frame) may comprise other shapes than the generally quadrangular illustrated in the present, exemplary figures. The stack and/or frame may as well be provided with three sides, or more than four sides, depending on the application and base plate into which the battery pack is intended to be integrated.

While the top terminal contact 322 may be fixed to the side frame 210, it is appreciated that the top terminal plate 321 may move in the stacking direction due to expansion and contraction of the cell stack. A flexible connection between the top terminal plate 321 and the top terminal contact 322 may therefore be provided. The flexible connection, also referred to as a flexible busbar 325 or flexible conductor, may be configured to absorb relative mechanical movements between the (fixed) top terminal contact 322 and the (moving) top terminal plate 321. The flexible connection 325 may for example comprise a flexible or bendable material allowing for the flexible connection 325 to vary its length in the stacking direction. The flexibility, i.e., the ability of allow a relative movement between the terminals connected by the flexible connection 325, may be achieved by the mechanical configuration of the connection (such as folds or a braiding), and/or inherent properties of the material of the connection (such as a bendable or flexible material). ln some examples, the connection 325 may comprise one or several sheets or wires that can be bent to allow the ﬂexible connection 325 to vary its length or be formed as a braided conductor.

According to a fifth aspect, an electrode plate assembly is provided, which may be similarly configured as the disclosure of the first aspect. Thus, a plurality of cells may be arranged in a vertical stack, wherein each cell comprises a positive electrode plate, a negative electrode plate and a separator interposed between the electrode plates. Further, an intermediate layer may be arranged between neighbouring or adjacent cells of the stack, wherein the intermediate layer is configured to electrically connect the neighbouring cells to each other. The cells of the stack may hence be connected in series, which the electrical contact at least partly provided by means of the intermediate layer. Thus, the adjacent cells may be arranged such that the positive electrode plate of a first one of the neighbouring cells is facing the negative electrode plate of the other one of the neighbouring cells, and the intermediate layer arranged in electrical contact with the positive and the negative electrode plate.

The intermediate layer may for instance comprise an electrically conductive adhesive. Examples of electrically conductive adhesives, or glues, include an electrically conductive component suspended in a continuous phase material, or matrix. The electrically conductive component may for instance comprise particles of a metal such as silver, nickel or copper, or another electrical conductor such as e.g. graphite. The matrix, or adhesive component may in some examples comprise a polymer, such as epoxy, resin or silicone.

The intermediate layer may be provided as a continuous layer or a patterned layer covering a substantial part of the surface of the electrode plates and may in some example be applied by spray coating or laminated ..;-,. ,,,-. 4,12! onto the cell. The thickness of the intermediate layer may for instance be of 10-100 um, such as about 50 um, depending on the cell stack configuration and the conductive properties of the intermediate layer.

Several effects may be achieved by providing the intermediate layer between adjacent cells. Firstly, the intermediate layer may be provided to join the cells electrically. The intermediate layer may be provided to fill out any irregularities between the adjoining surfaces and thereby improve the electrical contact. A pure mechanical contact, without any intermediate layer, may be more dependent on a low surface roughness to ensure a good electrical contact. The intermediate layer may thus serve the purpose of increasing the contact between the surfaces and compensate for any surface irregularities. Secondly, the intermediate layer may facilitate the mechanical bonding and increase the bonding strength between adjacent cells. ln this way an improved mechanical contact may be achieved, reducing the need for a relatively high and constant compression along the stacking direction. The intermediate layer may thus assist in maintaining electrical and mechanical contact between adjacent cells also during expansion and contraction of the stack along the stacking direction. Further, the intermediate layer may assist in keeping the cells in a correct position also in a lateral direction, i.e., preventing the cells from being displaced orthogonally to the stacking direction.

Figure 5 shows a top view of a cell 100 according to some embodiments, which may be similarly configured as any of the embodiments discussed above with reference to e.g. figures 1a-f. Thus, the cell 100 may comprise a first electrode plate 110 and a second electrode plate (not shown), having a separator (not shown) interposed therebetween. As illustrated in figure 5, an intermediate layer 510 may be arranged on an outer surface of the cell 100, such as the surface of the first electrode plate 110 facing away from the separator. The intermediate layer 510 may for example be provided as a substantially continuous layer covering a major part of the outer surface of the cell 100. ln the present example, the intermediate layer 510 may be formed by means of a spray coating tool 520.

According to a sixth aspect, a plurality of cells are arranged in a vertical stack, wherein each cell comprises a positive electrode plate and a negative electrode plate. The cell is configured to allow ions to move between the positive electrode plate and the negative electrode plate. Further, the electrode plate assembly may comprise a plurality of nanowires arranged between a first cell of the stack and a neighboring, second cell of the stack, electrically connecting the negative electrode plate of one of the cells to the positive electrode plate to the other one of the adjacent cells in a similar manner as described above in connection with the fifth aspect. Hence, the plurality of nanowires may in some examples be referred to as an intermediate layer. However, in the present aspect, such an intermediate layer may comprise a plurality of nanowires configured to electrically connect a first contact surface of the first cell to a second contact surface of the second cell.

The plurality of nanowires may be arranged on at least one of the first and second contact surfaces of the respective electrode plates or be arranged on a carrier arranged between first and second cells. The carrier may preferably be formed of an electrically conductive material, such as the same material at the nanowires. The nanowires may be arranged on both sides of the carrier, i.e., on a first surface facing the first contact surface of the first cell and on a second surface facing the second contact surface of the second cell. ln some examples, a plurality of carriers may be arranged in a stack extending between the neighboring cells, with the plurality of nanowires arranged between each carrier of the stack.

The nanowires may be formed of an electrically conductive material, such as copper, silver, nickel or gold, aluminum, or alloys thereof. All of the nanowires may be formed of the same material, or of at least two different materials such that some of the nanowires are formed from a first material and some of the nanowires from a second material. ln an example, the nanowires arranged on a first side of a carrier may be formed of a first material and the nanowires on a second side of the carrier of a second material, different from the first material. The nanowires may for example be formed of the same material as the contact surface of the cell to which they are bonded.

The carrier may have a thickness of 5 mm or less, such as in the range of 0.025 - 5 mm, and more preferably in the range of0.1 -1 mm. ln case there is provided a stack of a plurality of carriers, each carrier of the stack may have a thickness of 0.2 - 40 um. Further, the stack may have a thickness of 20 - 10000 um.

The nanowires may have a length in the range of 100 nm -100 um, such as 500 nm - 30 um. Further, they may have a thickness, or diameter, in the range of 10 nm - 10 um, such as 30 nm - 2 um.

The e|ectrode plate assembly may be formed by providing the plurality of nanowires on at least one of the first contact surface and the second contact surface of the respective cells and bonding the contact surfaces to each other. The nanowires may for instance be grown onto at least one of the first and second contact surfaces, for example by means of an electroplating process. ln further examples, the nanowires may be arranged on the carrier, for instance by means of electroplating, wherein the carrier in a subsequent step may be arranged between the cells that are to be bonded.

The bonding may be performed at room temperature, or at an increased temperature to facilitate bonding and provide an improved electrical contact between the cells. ln further examples, the bonding may be assisted by means of an applied pressure or under influence of ultrasound, which has shown to further improve the electrical characteristics of the bond. The applied pressure may for example be in the range of 3 - 200 MPa, such as 15 - 70 MPa or 20 MPa. The pressure may be applied in the stacking such that the intermediate layer is compressed and the contact surfaces forces towards each other.

Exemplary embodiments of the inventive concept and the technical context will now be explained in more detail with reference to figures 6-12. lt should be noted that the figures are schematic. Proportions and dimensions in the figures may be exaggerated and details may be omitted or merely indicated for illustrative purposes.

As mentioned above in connection with the fifth and sixth aspects, the intermediate layer may comprise a plurality of nanowires 601 configured to electrically connect the first contact surface 604 of the fist cell 602 to a second contact surface 605 of the second cell 603. This may also be referred to as bonding, in which an electrically conducting interface is formed, electrically and possibly mechanically coupling the contact surfaces to each other. The nanowires 601 can be provided directly on contact surfaces 604, 605 of cells to be connected, as shown in fig. 6, or on a carrier 606 as shown in fig. 7. ln further implementations, the nanowires may be provided in a stack of carriers, as shown in figs. 8-11.

A nanowire is understood as a structure having an elongated shape, for instance conforming to a wire, a finger or a thread, and a size in the range of a few nanometers (nm) to a few micrometers (um). ln the following, the term "nanowire" will be used when referring such a structure. Due to the size of the nanowires 601 in the nanometer range, the surface area of the bonding layer (i.e. the area over which forces such as the Van der Waals force act at the atomic level) may be relatively large. This allows for an electrical bond having a relatively low resistance, as well as a mechanical bond having improved strength. Further, an improved thermal conduction has been observed.

Advantageously, the present intermediate layer, comprising the nanowire structures, allows for the cells to be bonded to each other in a relatively easy and smooth process in which the contact surfaces 604, 605 are brought in contact with each other via the intermediate layer. Heat or pressure can be applied to further increase the quality of the bond but is not a requirement as the nanowire connection may be established already at room temperature.

The connection formed between the electrode plates of the first and second cells may be considered as a substantially metallic connection obtained by the plurality of nanowires 601, and in particular by the ends of the nanowires 601 which may be arranged to face the contact surfaces. This bond may be formed on an atomic level, in a process that may be similar to sintering. The obtained bond may be sufficiently impermeable to gases and/or "Ä :W e: liquids to protect the interconnected elements from corrosion at the bonding interface. Due to the multitude of nanowires 601, surface irregularities and surface defects may be compensated for and a more stable interconnection provided. Further, a plurality of carriers may be provided in a stacked structure to compensate for deviations in flatness, curvatures and a varying separation between the first and second cell when bonded to each other. The thickness of the stack may be selected to be sufficient to fill out any gap between the cells. The nanowires may further allow the carrier stack to be at least partly compressed to even out possible irregularities and deviations at the bonding interface. This is particularly advantageous when implemented in the electrode plate assemblies disclosed in the present application, as the electrode plate assemblies may have a relatively large electrode plate surface area (which may be more difficult to form in a completely planar manner) and rely on a direct electrical series connection between cells of the stack to function properly. The electrode plate assembly may hence be a large format assembly, in which the cells may have a typical size ranging from about 100 X 100 mm up to 1500 X 2500 mm or even more than 2500 mm. While typical dimensions may be 500 x 500 mm, 800 x 800 mm and 1000 x 1200 mm or 1000 x 2000 mm, it will be appreciated that the electrode plates and thus the cells may be cut into any desired shape depending on the base platform in which the assembly is to be used. Further, the present disclosure is not necessarily limited to rectangular or square shapes. The assembly may as well have a T-shape, a circular shape, triangular shape, hexagonal shape or any other shape that fits a battery pack.

A nanowire may have a circular, oval or polygonal cross section. ln particular, a nanowire may have a hexagonal cross section, depending on the method by which it is formed. The nanowires may be solid structures or hollow, such as tube shaped. Preferably, a nanowire 601 may have a length in the range of 100 nanometers (nm) to 100 micrometers (um), in particular in the range of 500 nm to 30 um. Furthermore, the nanowires 601 preferably have a diameter, or width in the range from 10 nm to 10 um, in particular in the range from 30 nm to 2 um. lt is particularly preferred that a majority, or most, of the nanowires 601 have a similar length and a similar diameter.

The nanowires 601 may be provided directly on one or both of the contact surfaces 604, 605, without the use of a carrier. Further, they may be formed of the same material as the contact surfaces 604, 605, such as for instance copper. ln further examples, the nanowires 601 may be provided on a carrier 606, as indicated in figure 7. The nanowires 601 may be arranged on one or both sides 607, 608 of the carrier 601 and then arranged to contact the contact surfaces 604, 605 of the cells. The bond may thus be formed by the nanowires 601 directly contacting the contact surfaces 604, 605. The nanowires 601 may preferably be formed of the same material as the carrier 606. The bonding characteristics of the nanowires 601 are known to vary with the material of which the nanowires 601 are formed as well as on the material of the surfaces to which the nanowires should bond. Depending on the type of materials of the first and second contact surfaces 604, 604 (which may be different from each other), the nanowires on a first side 607 of the carrier may be formed of a material that is different from the nanowires on a second side 608 of the carrier 606. Further, it will be appreciated that the carrier may be formed of the same material throughout, or by at least two different materials, such that the first side 607 of the carrier comprises a material that is different from the material at the second side 608 of the carrier 606.

For a connection with particularly good electrical and/or thermal conductivity, it is preferable that the nanowires 601 are formed from an electrically and/or thermally conductive material. The use of copper, silver, nickel, or gold is particularly preferred here. The material may also be aluminum, which may be advantageous due to its relatively low cost and weight. The contact surfaces 604, 605 are also preferably made of an electrically conductive material and/or thermally conductive material, in particular copper, silver, nickel or gold. Particularly preferably, the contact surfaces 604, 605 and the nanowires 601 are made of the same material. This makes the connection particularly stable. For a connection with particularly good electrical and/or thermal conductivity, it is preferable that the connection surfaces and the carrier 606 are formed from an electrically and/or thermally conductive material. "i på <1.

The nanowires 601 may be formed directly on a surface, such as on the carrier 606 or on a contact surface 604, 605 of a cell, by means of electrically assisted growth. An example of such as growth process is galvanic growth. Alternative methods for growing the nanowires are however conceivable, such as vapor-liquid-solid (VLS) growth, wherein a nanoscale liquid drop of catalyst facilitates the growth of solid nanowires using vapor phase reagents.

The nanowires 601 may extend substantially perpendicularly to the connection surface(s) 607, 608 - at least before joining the cells together. The entirety of the nanowires 601 on a connection surface can in particular be referred to as a lawn of nanowires 601.

However, the nanowires 601 can also be provided in other orientations on the surfaces that are to be bonded. lt is also possible to arrange the nanowires in several different regions, wherein the orientation of the nanowires may vary between different regions. This allows for a particularly stable and reliable connection that can withstand shear forces particularly well. Furthermore, it is possible for the nanowires 601 to be designed differently at different regions, in particular with regard to their length, diameter, material and strength (where the density of the nanowires 601 indicates how many nanowires 601 are provided per surface unit). Figures 12a-d show various examples of arrangements of nanowire regions 610 on the surfaces 604, 605 of the cells 602, 603. Figure 12a show an example wherein the entire surface, or at least a major part of the surface, such as more than 80%, preferably more than 90%, of the contact surface of the cell 602 is covered by the nanowires 601. Figures 12b and 12 c show other examples, wherein the surface that is to be bonded is provided with a plurality of distinct and separate nanowire regions 610. The regions 610 may have differently oriented nanowires 601, and/or nanowires of different shape, size or material, as mentioned above. Figure 12b shows plurality (in this case 9) regions 610 having a rectangular or square shape, whereas figure 12c show a plurality of regions 610 (such as 5) having a circular or oval shape. The nanowire regions 610 may also be referred to as patches of bonding material. A further example is shown in figure 12d, in which the nanowire regions 610 are provided as strips, such as a plurality of strips forming a frame shape around the edge of the cell area. Thus, it will be appreciated that the nanowire material may not necessarily cover the entire bonding area. lnstead, it may suffice to reduce the area covered with nanowires into one or more regions, which may be arranged in a regular pattern illustrated in figures 12b-d or an irregular pattern. Reducing the area covered by nanowires may reduce the cost and possibly weight of the stack.

The carrier 606 can be understood as an intermediary of the connection between the first cell 602 and the second cell 603. ln particular, as carrier 606 any physical object can be considered which is suitable to be placed between the contact surfaces 604, 605 of the cells to connect them by means of the nanowires. The nanowires may be arranged to protrude from one or more sides of the carrier. Preferably, the nanowires are arranged on opposing sides of the carrier to allow them to face both cells when arranged therebetween. ln alternative examples, however, the carrier may be configured to be attached directly onto a first one of the cells, without any intermediate nanowires in between. ln these examples, nanowires may be arranged on a surface of the carrier facing away from the first one of the cells, thereby allowing the nanowires to engage the other one of the cells. ln an embodiment, the carrier 606 can be film-like structure having a thickness of no more than 5 mm. Preferably, the thickness of the carrier 606 is in the range of0.025 mm and 5 mm, in particular in the range of 0.1 mm and 1 mm. Furthermore, it is preferred that the carrier 606 is designed in the shape of a tape. The first side and the opposite second side of the carrier 606 are in this form the two surfaces of the tape. The tape can, for example, be provided as a roll. The nanowires 601 may already be provided on one of both sides of the tape material and may be protected, for example, by a protective lacquer. Before using the carrier, the protective varnish can be removed and the nanowires 601 thus exposed. Carriers can also be provided as a stack of carriers comprising intermediate carriers 606', as illustrated in figures 9-11. ln some embodiments, illustrated in figure 7 and 8, the carrier 606 comprises a first surface facing the first contact surface 604 and a second surface facing the second contact surface 605, and wherein the plurality of nanowires 601 are arranged on the first and second surfaces of the carrier.

Figure 8 i||ustrates an embodiment, in which the cells 602, 603 are connected to each other indirectly via the carrier i||ustrated in figure 7. This has the advantage that nanowires 601 do not have to be formed directly on any of the cells 602, 603. lnstead, it is sufficient to form the nanowires 601 on the carrier 606. ln an embodiment, the carrier 606 can be provided as a stack of carriers wherein the plurality of nanowires 601 are arranged between each carrier 606' of the stack, as i||ustrated in figures 9-11. With the carriers arranged in a stack, non-planarities of the contact surfaces 604, 605 of the cells 602, 603 can be compensated particularly well despite the limited length of the nanowires 601. For this purpose, the stack of carriers may be divided into segments 609 along in the stacking direction. This allows the nanowires 601 to bridge a distance between the contact surfaces 604, 605 that is a multiple of the length of a single nanowire. Since the nanowires 601 are flexible, it is possible to compensate for unevenness in the contact surfaces 604, 605 that is greater than the length of a single nanowire.

The stack of carriers may in some examples comprise 2 to 20 segments 609, in particular 5 to 10. The stack of carriers can be connected to the two cells 602, 603 via the plurality of nanowires 601 in outer segments 609. The nanowires 601 of these two segments 609 can form a nanowire connection with one of the two components in each case. Thus, if more than two segments 609 are provided, there is at least one segment 609 that is not in direct contact with any of the cells 602, 603. These segments 609, together with the two outer segments 609, may serve as a mechanical buffer compensating for irregularities and non-planar contact surface 604, 605.

The nanowires 601 of the individual segments 609 are preferably oriented along the stacking direction. However, since nanowires 601 in practice are not always exactly straight, it is also preferred that the nanowires 601 have orientation deviating less than 30° from the stacking direction. The orientation of the nanowires 601 refers to the state before bonding. ln the case of uneven contact surfaces 604, 605, the segments 609 can be "E šš" * w compressed to compensate for the non-planarity. This can change the orientation of the nanowires 601. ln any case, the extension of the segments 609 along the stacking direction of the stack of carriers is significantly influenced by the length of the nanowires 601 before the stack of carriers forms a connection between two components.

The stack of carriers can be fabricated by growing the nanowires 601 segment 609 by segment 609 on the intermediate carriers 606'. The intermediate carriers 606' stabi|ize the interconnect element and prevent the nanowires 601 from breaking.

As shown in figure 11, neighboring intermediate carriers 606' are connected to each other via the nanowires 601. A distance between the adjacent intermediate carriers 606' along the stacking direction may hence correspond approximately to the length of the nanowires 601 arranged between these intermediate carriers 606'. Since in practice, the nanowires 601 often do not run exactly along the stacking direction, the distance between the adjacent intermediate carriers 606' along the stacking direction is preferably 90 to 100 % of the length of the nanowires 601 arranged between these intermediate carriers 606'.

The stack of carriers can have a thickness T along the stacking direction between 20 and 10000 pm, in particular between 100 and 600 pm. The intermediate carriers 606' along the stacking direction can each have a thickness t in the range of 0,2 pm to 40 pm, in particular in the range of 1 to 10 pm.

As mentioned above, the cells 602, 603 may be bonded to each other at room temperature. However, the bonding may also be performed at an elevated temperature, should the thermal budget of the cells allow so. ln some examples, the contact surfaces 604, 605 may be heated to a temperature of at least 150°C, preferably to a temperature of at least 170°C, such as at least 200°C or 270°C. The bond may be formed relatively fast, whereby it may be sufficient to maintain the elevated temperature for a relatively short period of time. The temperature to which the intermediate layer is heated may thus be maintained in 5 to 30 seconds to allow the bond to be formed. ln a further example, the stacked structure (comprising the first and second cells 602, 603 and the intermediate layer of nanowires) may be exposed to compressive forces in the stacking direction to further strengthen the bonding. The applied pressure may lie in the range of 3 - 200 MPa, such as 15 - 70 MPa. Particularly preferred is a pressure of 20 MPa. lt will further be appreciated that ultrasound may be applied to stimulate a sintering process in the nanowire material. ln the following, a numbered list of examples 1-33 is provided to further illustrate the inventive concept and the realisation thereof. The invention is however defined by the appended claims.

Example 1. An electrode plate assembly for a secondary battery module, the electrode plate assembly comprising a plurality of cells (100) arranged in a vertical stack (10); wherein each cell of the stack comprises a positive electrode plate (110), a negative electrode plate, and a separator; wherein the separator is interposed between the positive electrode plate and the negative electrode plate and configured allow ions to move between the positive electrode plate and the negative electrode plate; wherein the electrode plate assembly further comprises: a plurality of contacting means (140) for electrical monitoring of the cells, wherein each of the plurality of contacting means is electrically connected to at least one of the positive and negative electrode plates of a respective one of the cells and arranged to protrude laterally from a side edge (101, 102, 103) of the cell; wherein the contacting means are distributed spatially along a width (W) of the stack.

Example 2. The electrode plate assembly according to example 1, wherein the contacting means are staggered along the vertical direction.

Example 3. The electrode plate assembly according to example 1 or 2, wherein each of the plurality of contacting means comprises a tab.

Example 4. The electrode plate assembly according to example 3, wherein the tab is attached to a contact point on the positive or negative electrode plate, or integrally formed with said electrode plate.

Example 5. The electrode plate assembly according to example 1, further comprising: a plurality of sensors; and a plurality of wireless transmitters; wherein each of the plurality of sensors is coupled to a respective access point of a cell and configured to generate signal indicative of an operational parameter of said cell; wherein the access points are distributed spatially along a width (W) of the stack; and wherein each of the wireless transmitters is configured to transmit said signal.

Example 6. The electrode plate assembly according to example 5, wherein the operational parameter is at least one of a current, voltage and temperature of the cell.

Example 7. The electrode plate assembly according to any of the preceding examples, further comprising a side frame part (210) configured to be arranged at a side of the stack, wherein the side frame part comprises a plurality of slots (215), and wherein each of the slots is configured to receive a respective contacting means as the side frame part is being arranged at the side of the stack.

Example 8. The electrode plate assembly according to example 7, wherein the slots are configured to allow the contacting means to extend through the side frame.

Example 9. The electrode plate assembly according to example 7 or 8, wherein a width of each of the slots, as seen in the stacking direction of the stack, is larger than a thickness of each of the contacting means, as seen in the stacking direction, thereby allowing for the contacting means to move along the stacking direction in response to the stack swelling and shrinking.

Example 10. The electrode plate assembly according to any of examples 7-9, further comprising a plurality of contact pads (216) arranged adjacent to the slots, and wherein each of the contacting means is configured to be attached to a respective one of the contact pads.

Example 11. The electrode plate assembly according to example 10, wherein each of the contacting means is configured to be folded towards the respective contact pad.

Example 12. The electrode plate assembly according to any of examples 7- 11, wherein the side frame part comprises a printed circuit board (214).

Example 13. The electrode plate assembly according to any of examples 7- 12, wherein the side frame is a first side frame part, wherein the electrode plate assembly further comprises at least one second side frame part configured to be arranged at another side of the stack, and wherein the first side frame part and the at least one second sider frame part are configured to be assembled into a casing at least partly enclosing the stack.

Example 14. The electrode plate assembly according to any of the preceding examples, wherein the cells of the stack are electrically connected in series.

Example 15. The electrode plate assembly according to example 14, wherein neighbouring cells of the stack are electrically interconnected by means of a direct mechanical contact between the positive electrode plate of a first one of the neighbouring cells and the negative electrode plate of the other one of the neighbouring cells. '13 . <3 Example 16. The electrode plate assembly according to example 14, wherein neighbouring cells of the stack are joined by means of an intermediate layer.

Example 17. The electrode plate assembly according to example 16, wherein the neighbouring cells are arranged such that the positive electrode plate of a first one of the neighbouring cells is facing the negative electrode plate of the other one of the neighbouring cells, and wherein the intermediate layer is arranged in electrical contact with said positive electrode plate and said negative electrode plate.

Example 18. The electrode plate assembly according to example 16 or 17, wherein the intermediate layer comprises an electrically conductive adhesive.

Example 19. The electrode plate assembly according to any of examples 16- 18, wherein the intermediate layer is a continuous layer or a patterned layer.

Example 20. The electrode plate assembly according to any of the preceding examples, further comprising a bottom terminal plate arranged below the stack and a top terminal plate arranged above the stack, wherein the bottom terminal plate is arranged in electrical contact with a bottom one of the cells and the top terminal plate is arranged in electrical contact with a top one of the cells.

Example 21. The electrode plate assembly according to example 20, wherein the bottom terminal plate is electrically connected to the bottom one of the cells by means of an electrically conducting intermediate layer, and wherein the top terminal plate is electrically connected to the top one of the cells by means of an electrically conducting intermediate layer.

Example 22. The electrode plate assembly according to example 20 or 21, further comprising a top terminal contact and a flexible busbar electrically connecting the top terminal contact to the top terminal plate, thereby allowing for the top terminal plate to move relative the top terminal contact in response to the stack swelling and shrinking.

Example 23. The electrode plate assembly according to any of examples 20- 22, further comprising: a housing configured to accommodate the bottom terminal plate, the stack, and the top terminal plate, the housing comprising a base plate and a top cover configured to be attached to each other to form the housing; and an elastic means configured to be arranged between the top cover and the top terminal plate to exert a compressing force on the stack in the stacking direction.

Example 24. The electrode plate assembly according to example 23, wherein the elastic means covers a major portion of the stack, as seen in the stacking direction.

Example 25. The electrode plate assembly according to example 23 or 24, wherein the elastic means is a foam plate or a spring plate.

Example 26. An electrode plate assembly for a secondary battery module, the electrode plate assembly comprising a plurality of cells arranged in a vertical stack; wherein each cell of the stack comprises a positive electrode plate, a negative electrode plate, and a separator; wherein the separator is interposed between the positive electrode plate and the negative electrode plate and configured to allow ions to move between the positive electrode plate and the negative electrode plate; wherein the electrode plate assembly further comprises an intermediate layer arranged between neighbouring cells of the stack; and wherein the intermediate layer is configured to electrically connect the neighbouring cells to each other. í/-É ...:-.

Example 27. The electrode plate assembly according to example 26, wherein the neighbouring cells are arranged such that the positive electrode plate of a first one of the neighbouring cells is facing the negative electrode plate of the other one of the neighbouring cells, and wherein the intermediate layer is arranged in electrical contact with said positive electrode plate and said negative electrode plate.

Example 28. The electrode plate assembly according to example 26 or 27, wherein the intermediate layer comprises an electrically conductive adhesive.

Example 29. The electrode plate assembly according to any of examples 26- 28, wherein the intermediate layer is a continuous layer or a patterned layer.

Example 30. An electrode plate assembly for a secondary battery module, the electrode plate assembly comprising: a plurality of cells arranged in a vertical stack; wherein each cell of the stack comprises a positive electrode plate, a negative electrode plate, and a separator; wherein the separator is interposed between the positive electrode plate and the negative electrode plate and configured to allow ions to move between the positive electrode plate and the negative electrode plate; wherein neighbouring cells of the stack are arranged such that the positive electrode plate of a first one of the neighbouring cells is contacting the negative electrode plate of the other one of the neighbouring cells; the electrode plate assembly further comprising: a top terminal plate arranged above the stack and in electrical contact with a top one of the cells; a top terminal contact; and a flexible busbar electrically connecting the top terminal contact to the top terminal plate, thereby allowing for the top terminal plate to move relative the top terminal contact in response to the stack swelling and shrinking.

Example 31. An electrode plate assembly for a secondary battery module, the electrode plate assembly comprising: a plurality of cells arranged in a vertical stack; wherein each cell of the stack comprises a positive electrode plate, a negative electrode plate, and a separator; wherein the separator is interposed between the positive electrode plate and the negative electrode plate and configured to allow ions to move between the positive electrode plate and the negative electrode plate; wherein neighbouring cells of the stack are arranged such that the positive electrode plate of a first one of the neighbouring cells is contacting the negative electrode plate of the other one of the neighbouring cells; the electrode plate assembly further comprising: a top terminal plate arranged above the stack and in electrical contact with a top one of the cells; a housing configured to accommodate the top terminal plate, the housing comprising a top cover; and an elastic means configured to be arranged between the top cover and the top terminal plate to exert a compressing force on the stack in the stacking direction.

Example 32. The electrode plate assembly according to example 31, wherein the elastic means covers a major portion of the stack, as seen in the stacking direction.

Example 33. The electrode plate assembly according to example 31 or 32, wherein the elastic means is a foam plate or a spring plate.

Claims

1.Claims 1. An electrode plate assembly for a secondary battery module, the electrode plate assembly comprising a plurality of cells (100) arranged in a stack (10), wherein: each cell of the stack comprises a positive electrode plate (110), a negative electrode plate (120); the cell is configured to allow ions to move between the positive electrode plate and the negative electrode plate; and a first cell (602) of the stack and a neighboring, second cell (603) of the stack are joined by a plurality of nanowires (601) configured to electrically connect a first contact surface (604) of the first cell to a second contact surface (605) of the second cell.

2. The electrode plate assembly according to claim 1, wherein the plurality of nanowires are arranged on at least one of the first and second contact surfaces.

3. The electrode plate assembly according to claim 1 or 2, wherein the plurality of nanowires are formed of an electrically conductive material.

4. The electrode plate assembly according to any of the preceding claims, wherein the plurality of nanowires and at least one of the first contact surface and the second contact surface are formed of the same material.

5. The electrode plate assembly according to any of the preceding claims, wherein the plurality of nanowires are formed directly on at least one of the first and second contact surfaces (604, 605).

6. The electrode plate assembly according to any of the preceding claims, wherein the plurality of nanowires are arranged on a carrier 606 arranged between the first and second cell.

7. The electrode plate assembly according to claim 6, wherein the carrier comprises a first surface facing the first contact surface and a second surface facing the second contact surface, and wherein the plurality of nanowires are arranged on the first and second surfaces of the carrier.

8. The electrode plate assembly according to claim 6 or 7, wherein the carrier has a thickness of 5 mm or less, such as in the range of 0.05 - 5 mm, more preferably in the range of 0.1 -1 mm.

9. The electrode plate assembly according to any of claims 1-4, comprising a plurality of carriers 606' arranged in a stack between the neighboring first and second cells, wherein the plurality of nanowires are arranged between each carrier of the stack.

10. carriers 606' has a thickness in the range of 0.2 - 40 um. The electrode plate assembly according to claim 9, wherein each of the

11. The electrode plate assembly according to claim 9 or 10, wherein the stack of carriers 606' has a thickness of 20 - 10000 um in the stacking direction.

12. wherein each of the plurality of nanowires has a length in the range of 100 nm The electrode plate assembly according to any of the preceding claims, -100 um, such as 500 nm - 30 um.

13. wherein each of the plurality of nanowires has a thickness in the range ofThe electrode plate assembly according to any of the preceding claims, nm - 10 um, such as 30 nm -2 um.

14. wherein the plurality of nanowires are formed of at least one copper, nickel, The electrode plate assembly according to any of the preceding claims, silver and gold, or alloys thereof. ,~\ N - .\ Q <

15. wherein each of the cells is a large format cell, preferably having a size between 100 x 100 mm and 1500 x 2500 mm, such as 500 x 500 mm, such as 800 x 800 mm, such as 1000 x 1200 mm, such as 1000 x 2000 mm. The electrode plate assembly according to any of the preceding claims,

16. further comprising: The electrode plate assembly according to any of the preceding claims, a top terminal plate arranged above the stack and in electrical contact with a top one of the cells; a top terminal contact; and a flexible busbar electrically connecting the top terminal contact to the top terminal plate, thereby allowing for the top terminal plate to move relative the top terminal contact in response to the stack swelling and shrinking. comprising: The electrode plate assembly according to any of claims 1-15, further a top terminal plate arranged above the stack and in electrical contact with a top one of the cells; a housing configured to accommodate the top terminal plate, the housing comprising a top cover; and an elastic means configured to be arranged between the top cover and the top terminal plate to exert a compressing force on the stack in the stacking direction. 18. the preceding claims, comprising: A method of forming an electrode plate assembly according to any of providing the plurality of nanowires on at least one of the first contact surface of the first cell and the second contact surface of the second cell; and thereafter bonding the first contact surface to the second contact surface. 19. are electroplated onto at least one of the first and second contact surfaces. The method according to claim 18, wherein the plurality of nanowires í/å ,,,-. 4,12! 20. The method according to c|aim 18, wherein the plurality of nanowires are provided on a carrier, and wherein the method comprises arranging the carrier between the first and second contact surfaces. 21. The method according to c|aim 20, wherein the plurality of nanowires are electroplated onto the carrier. 22. The method according to c|aim 20 or 21, wherein the plurality of nanowires are arranged on a plurality of carriers, and wherein the plurality of carriers are arranged in a stack between the first cell and the second cell. 23. The method according to any of c|aims 18-22, wherein the bonding of the first contact surface to the second contact surface is performed at room temperature. 24. The method according to any of c|aims 18-22, wherein the bonding of the first contact surface to the second contact surface comprises heating at least one of the first and second contact surfaces to reduce the electrical resistance of the nanowire layer between the first and second cells. 25. The method according to any of c|aims 18-24, wherein the bonding of the first contact surface to the second contact surface comprises applying at least one of ultrasound and pressure to the stack formed by the first and the second cell. 26. The method according to c|aim 25, wherein the applied pressure lies in the range of 3 - 200 MPa, more preferably in the range of 15 - 70 MPa, such as 20 MPa.