Hollow cell, hollow battery and method of manufacturing a hollow cell

Abstract

CELL A hollow cell (100) comprising: an electrode assembly (200); and a housing containing the electrode assembly, the housing defining a conduit (310) extending entirely therethrough, wherein the electrode assembly is arranged around the conduit.

Description

[0001] 1 P005146-W001

[0002] Cell

[0003] BACKGROUND

[0004] Cells and batteries are used to power a wide array of devices and systems across many different applications. Cells and batteries are available in a variety of shapes and sizes and are typically provided in a casing that has the form factor of a solid shape.

[0005] SUMMARY

[0006] At its most general, the present disclosure provides a hollow cell or a hollow battery.

[0007] A hollow cell may be a cell having a conduit extending entirely therethrough. By extending entirely therethrough, the conduit may pass through a housing of the cell such that the conduit can provide a pathway for matter, such as fluid, to pass through the cell.

[0008] A hollow battery may comprise multiple hollow cells. The hollow battery may comprise a plurality of hollow cells arranged such that the conduits of each hollow cell align to form a continuous conduit extending through the battery.

[0009] According to a first aspect, there is provided a hollow cell comprising: an electrode assembly; and a housing containing the electrode assembly, the housing defining a conduit extending entirely therethrough, wherein the electrode assembly is arranged around the conduit.

[0010] A cell may be referred to as a device for releasably storing electrical potential energy. One or more cells may be provided to power a device by releasing electrical energy.

[0011] Cells are typically formed from a housing that encases an electrode assembly entirely therein. The electrode assembly may comprise two or more electrode plates separated by an insulator.

[0012] The hollow cell of the present disclosure may be differentiated from conventional cells in that the housing of the hollow cell may comprise a conduit extending entirely therethrough. 2 P005146-W001

[0013] The conduit, or passage, may be a hollow or void extending through the housing. Put another way, the housing may be provided around, or circumscribe, the conduit.

[0014] For example, the conduit may define a fluid pathway through the cell. For example, fluid, such as air or liquid, may flow through the cell by way of the conduit.

[0015] The housing may be provided concentrically around the conduit. In conventional cells, the centre of the cell often experiences the highest temperatures. By providing the housing, and so the electrode assembly, about the conduit, the hollow cell may be cooled more efficiently. In some examples, a flow of fluid through the conduit may be used to cool the hollow cell.

[0016] In some examples, the conduit may be used to accommodate wiring, motors and / or other auxiliaries of a product into which the cell is incorporated. This may help to increase the packing efficiency of the product.

[0017] The housing may be formed from a material comprising or consisting of one more of steel, nickel plated steel and aluminium.

[0018] The conduit may have any suitable cross-sectional shape. The housing may have any suitable cross-sectional shape. The conduit and the housing may have the same cross- sectional shape. The conduit and the housing may have different cross-sectional shapes. The conduit may have a circular cross-section. The housing may have a ring cross-section.

[0019] In examples where the conduit has a circular cross-section, the housing may substantially take the form of a cylindrical shell. A cylindrical shell may have an outer radius, a thickness and an inner radius, wherein the outer radius is equal to the sum of the inner radius and the thickness. In examples where the housing substantially takes the form of a cylindrical shell, the conduit may be defined by the inner radius of the cylindrical shell, the outer perimeter of the cell may be defined by the outer radius of the cylindrical shell and the electrode assembly may be provided within the thickness of the cylindrical shell, between the inner radius and the outer radius. 3 P005146-W001

[0020] In some examples, the electrode assembly may surround, for example may entirely surround, a perimeter of the conduit.

[0021] In examples where the conduit has a circular cross section and the housing takes the form of a cylindrical shell, the electrode assembly may also substantially take the form of a cylindrical shell, enclosed within the cylindrical shell of the housing. In particular, the inner radius of the electrode assembly may be greater than the inner radius of the housing and the outer radius of the electrode assembly may be less than the outer radius of the housing, such that the thickness of the electrode assembly is less than the thickness of the housing.

[0022] In some examples, the housing may comprise a first terminal provided at a first end of the housing and a second terminal provided at a second end of the housing, opposite the first end of the housing. The conduit may extend through the first terminal and the second terminal such that the first terminal and the second terminal surround the conduit.

[0023] Put another way, the first terminal and the second terminal may circumscribe the conduit in a similar manner to the housing. Accordingly, the first and second terminal may define further portions of the passage defined by the housing. For example, fluid, such as air, flowing through the hollow cell may enter the conduit through the first terminal, flow along the conduit through the housing and leave the conduit through the second terminal.

[0024] The first terminal and the second terminal may provide the electrical connections for the hollow cell. The first terminal may be an opposite polarity to the second terminal. For example, the first terminal may be a positive terminal and the second terminal may be a negative terminal. In another example, the first terminal may be a negative terminal and the second terminal may be a positive terminal.

[0025] The electrode assembly may be electrically connected to the first terminal and the second terminal as outlined in further detail below. 4 P005146-W001

[0026] In some examples, the second terminal may be proportioned to be receivable within the first terminal.

[0027] Put another way, an outer dimension of the second terminal may be smaller than an inner dimension of the first terminal. In other words, the second terminal may be sized and shaped to be receivable within the portion of the conduit that passes through the first terminal.

[0028] In use, for a single hollow cell, the second terminal of a given hollow cell may not be received within the first terminal of the same hollow cell. However, for multiple hollow cells, the second terminal of a given hollow cell may be received within, and directly or indirectly electrically connected to, the first terminal of another hollow cell.

[0029] For example, when the first terminal and the second terminal are circular, or ring-shaped, the outer diameter of the second terminal may be less than an inner diameter of the first terminal.

[0030] In some examples, the housing may comprise an outer housing portion. The housing may comprise an inner housing portion. The inner housing portion may define the conduit extending through the housing. The electrode assembly may be provided between the outer housing portion and the inner housing portion.

[0031] The outer housing portion may be a unitary housing portion. The outer housing portion may be a composite housing portion formed from a plurality of sub-portions. The outer housing portion may be formed from a conductive material. The outer housing portion may be formed from metal.

[0032] The inner housing portion may be a unitary housing portion. The inner housing portion may be a composite housing portion formed from a plurality of sub-portions. The inner housing portion may be formed from a conductive material. The inner housing portion may be formed from metal. 5 P005146-W001

[0033] The outer housing portion and the inner housing portion may have cooperating geometries. The outer housing portion and the inner housing portion may have substantially the same shape, but different scales. The volume of the outer housing portion may be larger than the volume of the inner housing portion.

[0034] The inner housing portion may be received within the outer housing portion. The electrode assembly provided between the inner housing portion and the outer housing portion may be received within the outer housing portion.

[0035] In examples where the hollow cell has the form of a cylindrical shell, the outer housing portion may be substantially cylindrical and may define the outer radius of the cylindrical shell. In this example, the inner housing portion may be substantially cylindrical and may define the inner radius of the cylindrical shell. In this example, the electrode assembly may be provided within the volume of the cylindrical shell.

[0036] The inner housing portion may define the conduit extending through the housing. In other words, a surface of the inner housing portion may form the boundary between the conduit and the interior of the hollow cell (i.e., the volume of the hollow cell comprising the electrode assembly).

[0037] The cross-section of the inner housing portion may define the cross-section of the conduit. The length of the inner housing portion may be commensurate with the length of the hollow cell.

[0038] The inner housing portion and the outer housing portion may be concentric. The electrode assembly may be concentric with the inner housing portion and the outer housing portion. The electrode assembly may be encapsulated between the inner housing portion and the outer housing portion.

[0039] The outer housing portion may be attached directly or indirectly to the inner housing portion. The outer housing portion may be attached directly or indirectly to the inner housing portion at multiple attachment points. For example, part of the outer housing 6 P005146-W001 portion may be welded to part of the inner housing portion. For example, part of the outer housing portion may be crimped to the inner housing portion.

[0040] In some examples, a first end of the inner housing portion may form at least part of the first terminal. A second end of the inner housing portion, opposite the first end of the inner housing portion, may form at least part of the second terminal.

[0041] In some examples, the inner housing portion may comprise a conduit insulation layer. The conduit insulation layer may have a conduit surface facing the conduit. The inner housing portion may comprise an inner internal insulation layer. The inner internal insulation layer may have an inner insulation surface facing the electrode assembly. The inner housing portion may comprise an inner conductive layer provided between the conduit insulation layer and the inner internal insulation layer.

[0042] The inner conductive layer may be sandwiched between the conduit insulation layer and the inner insulation layer. The inner conductive layer may be formed from a conductive material, such as metal. The conduit insulation layer and the inner insulation layer may be formed from a non-conductive, i.e., insulating, material, such as a plastic, for example polypropylene.

[0043] The inner conductive layer may extend from between the conduit insulation layer and the inner insulation layer to provide a first exposed portion of the inner conductive layer. The first exposed portion of the inner conductive layer may form at least part of the first terminal.

[0044] The conduit insulation layer may protect the surface of the inner housing portion of the hollow cell that defines the conduit, for example from matter passing through the hollow cell via the conduit, such as matter suspended in a flow of air. The conduit insulation layer may prevent the hollow cell from short circuiting, or arcing, to matter passing through the hollow cell via the conduit, such as matter suspended in a flow of air. 7 P005146-W001

[0045] In some examples, the inner conductive layer may comprise an elongate tubular portion. The conduit may extend through the elongate tubular portion. The inner conductive layer may comprise a flange circumscribing a first end of the elongate tubular portion. The flange may form at least part of the first terminal.

[0046] The elongate tubular portion may extend in a longitudinal direction, for example along a length of the hollow cell. The flange may project radially from the elongate tubular portion. The flange may project in a transverse direction, perpendicular to the longitudinal direction. The flange may project from the elongate tubular portion in a direction away from the conduit.

[0047] In some examples, the inner housing portion may comprise a conductive support member provided at the second end of the inner housing portion. The conductive support member may form at least part of the second terminal.

[0048] The conductive support member may be received within the conduit defined by the inner housing portion. The conductive support member may surround, and define, a portion of the conduit in a similar manner to the inner housing portion. The conductive support member may have a geometry cooperative with the geometry of the inner housing portion.

[0049] In examples where the inner housing portion is cylindrical, the conductive support member may be cylindrical. The diameter of the conductive support member may be less than the diameter of the inner housing portion. The conductive support member may be friction fit to the inner housing portion.

[0050] In some examples, the conductive support member may be received within the elongate tubular portion of the inner conductive layer. The conductive support member may be electrically isolated from the inner conductive layer by the conduit insultation layer.

[0051] Put another way, the conduit insulation layer may extend between the conductive support member and the inner conductive layer so as to insulate the conductive support member from the inner conductive layer. In this way, the conductive support member forming part 8 P005146-W001 of the second terminal may be isolated from the flange of the inner conductive layer forming part of the first terminal, thereby preventing a short circuit occurring within the hollow cell.

[0052] In examples where the second terminal of a given hollow cell is received within the first terminal of another hollow cell, the conductive support portion of the given hollow cell may become electrically coupled to the inner conductive layer of the other hollow cell in order to electrically connect the hollow cells in series.

[0053] In some examples, the outer housing portion may comprise an outer conductive layer. The outer housing portion may comprise an outer internal insulation layer provided on an inner surface of the outer conductive layer and having an outer insulation layer surface facing the electrode assembly.

[0054] The outer conductive layer may be formed from a conductive material, such as metal. The outer internal insulation layer may be formed from a non-conductive, i.e., insulating, material, such as a plastic, for example polypropylene.

[0055] The electrode assembly may be sandwiched between the inner internal insulation surface of the inner housing portion and the outer internal insulation surface of the outer housing portion.

[0056] In some examples, the outer conductive layer may be electrically connected to the first terminal and electrically isolated from the second terminal.

[0057] The outer conductive layer may be electrically isolated from the second terminal by the outer internal insulation surface, which may be provided between the outer conductive layer and the conductive support member.

[0058] The outer conductive layer may be electrically connected to the inner conductive layer at the flange of the inner conductive layer. 9 P005146-W001

[0059] In some examples, the electrode assembly may comprise a first electrode layer and a second electrode layer. The electrode assembly may comprise a middle separator layer provided between the first electrode layer and the second layer.

[0060] The first electrode layer may be an anode and the second electrode layer may be a cathode. The first electrode layer may be a cathode and the second electrode layer may be an anode. The middle separator layer may be an insulator for insulating the first electrode layer from the second electrode layer.

[0061] The electrode assembly may be a jelly roll style assembly. The jelly roll assembly may be centred on the conduit of the hollow cell, such that the centre of the jelly roll may define a void through which the conduit passes. The jelly roll assembly may be rolled around the inner housing portion of the hollow cell. The jelly roll assembly may take the form of a cylindrical shell received within the cylindrical shell defined by the inner and outer housing portions of the hollow cell.

[0062] The first electrode layer may comprise a negative active material. The negative active material may comprise or consist of one or more of graphite, silicon, silicon oxide, prelithiated silicon, prelithiated silicon oxide, lithium-silicon metal alloys, SiC composites.

[0063] The first electrode layer may comprise the negative active material in an amount of at least about 10 wt% of the first electrode layer, such as in an amount of at least about 50 wt% or even at least about 80 wt% of the first electrode layer. For example, the first electrode layer may comprise the negative active material in an amount in the range of from 80 wt% to 99 wt%, or from 80 wt% to 97 wt%, or from 80 wt% to 95 wt%, or from 80 wt% to 90 wt%, or from 80 wt% to 85 wt%, or from 85 wt% to 95 wt% of the first electrode layer.

[0064] Suitably, the first electrode layer may comprise the negative active material in an amount of about 80 wt% of the first electrode layer. Alternatively, the first electrode layer may comprise the negative active material in an amount of about 85 wt%, or about 90 wt%, or about 95 wt%, or about 97 wt%, or about 99 wt% of the first electrode layer. 10 P005146-W001

[0065] The negative active material may comprise or consist of a mixture of silicon and graphite. The mixture of silicon and graphite may consist of silicon and graphite in a weight ratio in the range of from 1 : 19 to 1 : 1 (i.e. 1 : 19 silicon to graphite to 1 : 1 silicon to graphite). For example, the mixture of silicon and graphite may consist of silicon and graphite in a weight ratio in the range of from 1 :9: to 1 : 1, or in the range of from 1 :9 to 4:6, or in the range of from 1 :9 to 3:7, or in the range of from 1 :9 to 2:8. Suitably, the mixture of silicon and graphite may consist of silicon and graphite in a weight ratio of about 1 :9.

[0066] In the manufacture of conventional wound cells, in which the electrode assembly is a jelly roll arrangement, the electrode assembly may be wound around a thin mandrel and the mandrel may be removed before the electrode assembly is inserted into a housing, leaving a void in the centre of the electrode assembly. In such conventional wound cells, the amount of negative active material in the anode is typically around 85 to 95 wt%, and the negative active mixture is a mixture of silicon and graphite.

[0067] In such conventional wound cells, the amount of silicon that can be used in the negative active mixture is typically limited to around 5 to 8 wt%. This is because silicon expands more than graphite as it becomes lithiated during use of the cell, and so the use of higher amounts of silicon in the negative active material can cause buckling of the jelly roll into the void in the centre of the electrode assembly.

[0068] By contrast, in hollow cells according to the present disclosure, the electrode assembly is arranged around the conduit and so a greater degree of expansion may be tolerated as there is no void at the centre of the electrode assembly. Thus, higher amounts of silicon may be used in the negative active material, resulting in an increased capacity of the first electrode layer.

[0069] The second electrode layer may comprise or consist of a positive active material. The positive active material may be a lithium transition metal oxide material. The positive active material may be a lithium transition metal oxide material comprising a mixed metal oxide of lithium and one or more transition metals, optionally further comprising one or more additional non-transition metals. The positive active material may be a lithium 11 P005146-W001 transition metal oxide material comprising lithium and one or more transition metals selected from nickel, cobalt and manganese.

[0070] The positive active material may be selected from one or more of lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel cobalt oxide (NCO), aluminium- doped lithium nickel cobalt oxide (NCA), lithium nickel manganese cobalt oxide (NMC), lithium nickel oxide (LNO), lithium nickel manganese oxide (LNMO), lithium iron phosphate (LFP), lithium manganese iron phosphate (LMFP) and lithium nickel vanadate (LNV). Suitably, the positive active material may be lithium nickel manganese cobalt oxide (NMC), optionally doped with another metal such as aluminium. Such positive active materials are commercially available or may be manufactured by methods known to the skilled person, for example through the precipitation of mixed metal hydroxide intermediates from a reaction mixture containing different precursor metal salts, followed by calcination to form a mixed metal oxide and optionally lithiation to incorporate lithium into the oxide.

[0071] The second electrode layer may comprise or consist of a loading of positive active material of at least 200 grams per square metre (GSM), for example at least 250 GSM. The second electrode layer may comprise or consist of a loading of positive active material of in the range of from 250 to 1000 GSM, or from 250 to 750 GSM, or from 250 to 500 GSM, or from 250 to 350 GSM. The second electrode layer may comprise or consist of a loading of positive active material of in an amount of about 250 GSM, or about 300 GSM, or about 400 GSM, or about 500 GSM, or about 600 GSM, or about 700 GSM, or about 800 GSM, or about 900 GSM, or even about 1000 GSM.

[0072] In the manufacture of conventional wound cells, the jelly roll is typically wound around a thin mandrel. In such conventional wound cells, the loading of positive active material in the electrode layer is typically limited to around 200 to 250 GSM. Without wishing to be bound by theory, the use of higher loadings of positive active material in conventional wound cells can reduce the flexibility of the jelly roll. 12 P005146-W001

[0073] This can be problematic, due to the tight radius of curvature required to wrap the jelly roll around the mandrel at the centre of the cell. Hence, the use of higher loadings of positive active material in the electrode layer in conventional wound cells can lead to wrinkling of the jelly roll to create unwanted voids in the cell, and / or the formation of cracks in the jelly roll.

[0074] By contrast, in hollow cells according to the present disclosure, the electrode assembly is arranged around the conduit and so the radius of curvature of the jelly roll in the present disclosure may be significantly larger than in conventional wound cells. This may therefore enable higher loadings of positive active material to be used in the second electrode layer without causing wrinkling of the jelly roll to create unwanted voids in the cell, and / or the formation of cracks in the jelly roll.

[0075] The first and second electrode layers may be insulated from the inner and outer housing portions of the hollow cell by the inner internal insulation surface of the inner housing portion and the outer internal insulation surface of the outer housing portion.

[0076] The first electrode layer may comprise a first tab portion protruding from a first end of the electrode assembly for contacting the first terminal. The second electrode layer may comprise a second tab portion protruding from a second end of the electrode assembly for contacting the second terminal.

[0077] When the electrode assembly is a jelly roll style assembly, the presence of the first and / or second tab portions at the ends of the electrode assembly may avoid the need to attach tabs along discrete intervals of the wound jelly roll, which can lead to very high stress concentrations within the jelly roll and inhomogeneous radial pressures throughout the lengths of the electrode layers. This can lead to poor cycling performance and the risk of buckling and internal short circuits. Moreover, attaching tabs along discrete intervals of the wound jelly roll can cause the resistance to increase as the electric path defined by the electrode layers becomes longer. 13 P005146-W001

[0078] In examples where the first electrode layer is a cathode and the second electrode layer is an anode, the first terminal may be the negative terminal and the second terminal may be a positive terminal. In examples where the first electrode layer is an anode and the second electrode layer is a cathode, the first terminal may be the negative terminal and the second terminal may be a positive terminal.

[0079] The first tab portion of the first electrode layer may be electrically coupled to the inner conductive layer of the inner housing portion, for example at the flange or the elongate tubular portion of the inner conductive layer. The second tab portion of the section electrode layer may be electrically coupled to the conductive support member.

[0080] The structure of the electrode assembly about the conduit through the inner housing portion may result in the first and second tab portions being arranged in a spiral at either end of the electrode assembly.

[0081] In some examples, the housing may comprise a first clamping member for clamping the first tab portion of the first electrode layer to the flange. In some examples, the housing may comprise a first clamping member for clamping the first tab portion of the first electrode layer to the elongate tubular portion.

[0082] The first clamping member may take any suitable form for clamping the first tab portion to the inner conductive layer. For example, the first clamping member may be a split ring provided over the first tab portion such that the first tab portion may be clamped between the split ring and the inner conductive layer of the inner housing portion. The split ring may be welded into place.

[0083] The use of a split ring as the first clamping member may provide secure clamping of the first tab portion whilst also improving the ease of manufacture of the hollow cell as the split ring can be simply moved into place and welded after the electrode assembly is in place. 14 P005146-W001

[0084] In some examples, the housing may comprise a second clamping member for clamping the second tab portion of the second electrode layer to the conductive support member.

[0085] The second clamping member may take any suitable form for clamping the second tab portion to the conductive support member.

[0086] In some examples, the second clamping member may be a slip ring adapted to fit over the conductive support member to clamp the second tab portion between the second clamping member and the conductive support member.

[0087] The use of a slip ring as the second clamping member may provide secure clamping of the second tab portion whilst also improving the ease of manufacture of the hollow cell, as the slip ring can be simply moved into place and secured after the electrode assembly is in place.

[0088] According to a second aspect, there is provided a hollow battery comprising a plurality of hollow cells as described above, arranged such that a first hollow cell of the plurality of hollow cells is electrically connected to a second hollow cell of the plurality of hollow cells.

[0089] In some examples, the plurality of hollow cells of the hollow battery may be arranged such that the first terminal of the first hollow cell may be received within the second terminal of the second hollow cell.

[0090] The conduit of the first hollow cell may align with the conduit of the second hollow cell to form an extended common conduit extending entirely through the hollow battery.

[0091] According to a third aspect, there is provided a method of manufacturing a hollow cell comprising a housing defining a conduit extending entirely therethrough, the method comprising: providing an electrode assembly around the conduit defined by the housing. 15 P005146-W001

[0092] In some examples, the housing may comprise an inner housing portion defining the conduit extending through the housing. Providing the electrode assembly around the conduit may comprise providing the electrode assembly about the inner housing portion of the housing.

[0093] In some examples, providing the electrode assembly about the inner housing portion may comprise: arranging the inner housing portion on a spindle such that the spindle is received within the conduit; affixing a first end of the electrode assembly to the inner housing portion; and rotating the spindle, thereby rotating the inner housing portion received on the spindle and winding the electrode assembly onto the inner housing portion.

[0094] As mentioned above, in conventional wound cell manufacture, where the electrode assembly is a jelly roll arrangement, the electrode assembly may be wound around a thin mandrel and then the mandrel may be removed before the electrode assembly is inserted into the housing, leaving a void in the centre of the electrode assembly, into which the electrode assembly often deforms over multiple charging cycles.

[0095] By winding the electrode assembly directly onto the inner housing portion, the supporting structure of the electrode assembly may be maintained from manufacture to final assembly of the hollow cell, meaning that the electrode assembly may be less prone to deformation over time.

[0096] Moreover, the tight radius of curvature required to wrap the jelly roll around a thin mandrel can restrict the type of materials that can be used in the jelly roll in a conventional cell, as only materials that are sufficiently flexible to tolerate the tight bend radius may be used. In contrast, by winding the jelly roll onto the inner housing portion, the radius of curvature provided by the present disclosure may be significantly larger, allowing for the use of materials that are not typically used in the jelly roll of a conventional cell.

[0097] In some of the examples outlined above, an inner conductive layer of the inner housing portion may comprise an elongate tubular portion. The conduit may extend through the elongate tubular portion and a flange circumscribing a first end of the elongate tubular portion. The flange may form at least part of the first terminal. The inner housing portion 16 P005146-W001 may comprise a conductive support member provided at a second end of the inner housing portion, opposite the first end of the inner housing portion. The conductive support member may form at least part of the second terminal. The electrode assembly may comprise a first electrode layer comprising a first tab portion protruding from a first end of the electrode assembly. The electrode assembly may comprise a second electrode layer comprising a second tab portion protruding from a second end of the electrode assembly, opposite the first end of the electrode assembly. The electrode assembly may comprise a middle separator layer provided between the first electrode layer and the second layer.

[0098] The method may comprise clamping the first tab portion to the flange using a first clamping member and / or clamping the second tab portion to the conductive support member using a second clamping member.

[0099] In some examples, the hollow cell may comprise an outer housing portion. The method may comprise providing the outer housing portion over the electrode assembly and the inner housing portion such that the electrode assembly may be provided between the outer housing portion and the inner housing portion.

[0100] BRIEF DESCRIPTION OF THE DRAWINGS

[0101] Figure 1 shows a schematic representation of a hollow cell.

[0102] Figure 2 shows an inner housing portion of a hollow cell.

[0103] Figure 3 shows an inner housing portion of a hollow cell having insulation layers applied thereto.

[0104] Figure 4 shows a cross section of an inner housing portion of a hollow cell.

[0105] Figure 5 shows a partially exploded view of a hollow cell.

[0106] Figure 6 shows a schematic cross section of a hollow cell. 17 P005146-W001

[0107] Figure 7 shows a hollow battery comprising multiple hollow cells.

[0108] Figure 8 shows a method of manufacturing a hollow cell.

[0109] DETAILED DESCRIPTION

[0110] The same reference numerals are used to refer to the same features across different Figures.

[0111] Figure 1 shows a schematic representation of a hollow cell 100.

[0112] The hollow cell 100 shown in Figure 1 comprises an electrode assembly 200 and a housing 300 containing the electrode assembly 200. The housing 300 defines a conduit 310 extending entirely through the housing 300. The electrode assembly 200 is arranged around, and surrounds the perimeter of, the conduit 310.

[0113] In the example shown in Figure 1, the conduit 310 is a cylindrical passage passing through the housing 300. The housing 300 is also cylindrical, and so takes the form of a cylindrical shell due to the conduit 310. Correspondingly, the electrode assembly 200, which is arranged around the conduit 310, also takes the from of a cylindrical shell housed within the volume of the cylindrical shell of the housing 300.

[0114] The inner radius 201 of the electrode assembly 200 is greater than the inner radius 301 of the housing 300 and the outer radius 202 of the electrode assembly 200 is less than the outer radius 302 of the housing 300, such that the thickness of the electrode assembly 203 is less than the thickness of the housing 303.

[0115] The inner radius 301 of the housing 300 may be between 14mm and 16mm and the outer radius 302 of the housing 300 may be between 17mm and 18mm. The hollow cell 100 may be 80mm in length. The outer radius 302 of the housing may be between 15mm and 60mm. 18 P005146-W001

[0116] The electrode assembly 200 may comprise multiple layers of electrodes and separators as described in further detail below. The electrode assembly may be wound around the conduit 310 from 3 to 10 times. The hollow cell may have a capacity of between 2 to 7Ah.

[0117] Figure 2 shows an inner housing portion 320 of a hollow cell. In particular, Figure 2 shows an inner conductive layer 321 of the inner housing portion 320.

[0118] The inner conductive layer 321 comprises an elongate tubular portion 322 and a flange 324 circumscribing a first end 325 of the elongate tubular portion 322. The conduit 310 extends through the elongate tubular portion 322 of the inner conductive layer 321. The flange 324 forms part of the first terminal of the hollow cell as described in further detail below.

[0119] Figure 3 shows the inner housing portion 320 of Figure 2 having insulation layers applied thereto.

[0120] In the example shown in Figure 3, a conduit insulation layer 332 has been applied to the conduit facing surface of the inner conductive layer 321 and an inner internal insulation layer 334 has been applied to the surface of the inner conductive layer 322 facing the electrode assembly 200.

[0121] The elongate tubular portion 322 of the inner conductive layer 321 is sandwiched between the conduit insulation layer 332 and the inner insulation layer 334. As shown in Figure 3, a portion of the inner conductive layer 321 extends from between the conduit insulation layer 332 and the inner insulation layer 334 to provide a first exposed portion 322a of the inner conductive layer 321.

[0122] Figure 4 shows a cross section of the inner housing portion 320 of Figure 2 with a conductive support member 338 provided at the second end 326 of the inner housing portion 320.

[0123] The conductive support member 338 forms part of the second terminal of the hollow cell as described in further detail below. 19 P005146-W001

[0124] As shown in Figure 4, the conductive support member 338 is received within the elongate tubular portion 322 of the inner conductive layer. The conduit insulation layer 332 (not shown in Figure 4) is provided between the conductive support member 338 and the inner conductive layer elongate tubular portion 322 of the inner conductive layer.

[0125] Figure 5 shows a partially exploded view and an assembled view of a hollow cell 100 comprising the inner housing portion 320 shown in Figure 4 and an electrode assembly 200.

[0126] In addition to the inner housing portion 320, the hollow cell 100 comprises an outer housing portion 350. The outer housing portion 350 comprises an outer conductive layer 352 and an outer internal insulation layer 354 provided on an inner surface of the outer conductive layer 352. When assembled, the electrode assembly 200 is sandwiched between the inner internal insulation surface 344 of the inner housing portion 320 and the outer internal insulation surface 354 of the outer housing portion 350.

[0127] The hollow cell 100 further includes a second clamping member, in the form of a slip ring 360, the function of which is described in further detail below. The slip ring 360 is adapted to fit over the conductive support member 338.

[0128] Figure 6 shows a schematic cross section of a hollow cell 100.

[0129] In the example shown in Figure 6, the housing comprises a first terminal 110 provided at a first end of the housing 300, and in particular at a first end of the inner housing portion and specifically at the flange 324, and a second terminal 120 provided at a second end of the housing 300, opposite the first end of the housing, and in particular at a second end of the inner housing portion and specifically at the conductive support member 338. The conduit 310 extends through the first terminal 110 and the second terminal 120 such that the first terminal and the second terminal surround the conduit 310 such that a flow of air 311 may pass through the hollow cell 100. The outer conductive layer 352 is electrically connected to the inner conductive layer at the flange 324. 20 P005146-W001

[0130] The electrode assembly 200 is electrically connected to the first terminal 110 and the second terminal 120. In the example shown in Figure 6, a first tab portion 210 protruding from a first electrode layer of the electrode assembly 200 contacts the inner conductive layer of the inner housing portion, for example at the flange 324 or at the first exposed portion 322a of the inner conductive layer, to form the first terminal. The first tab portion 210 can be clamped or welded in place with a first clamping member (not shown). The first tab portion 210 may be formed from copper.

[0131] A second tab portion 220 protruding from a second electrode layer of the electrode assembly 200, the second electrode layer being separated from the first electrode layer by a middle separator layer, contacts the conductive support member 338 and can be clamped or welded in place with the slip ring 360 to form the second terminal 120. The second tab portion 220 may be formed from aluminium.

[0132] Figure 7 shows an exploded view of a hollow battery 400 comprising three hollow cells 100 as described above. It will be understood that any number of hollow cells 100 may be used to form a hollow battery.

[0133] In the example shown in Figure 7, the hollow cells 100 are arranged such that the second terminal 120a of a first hollow cell 100a is received within the first terminal 110b of a second hollow cell 100b such that the first hollow cell 100a is electrically connected to the second hollow cell 100b.

[0134] Figure 8 shows a method 500 of manufacturing a hollow cell 100 as described above.

[0135] The method may begin in step 510 by providing an electrode assembly 200 around the conduit 310 defined by the housing 300. The electrode assembly 200 may be provided around the conduit 310 by providing 520 the electrode assembly 200 about the inner housing portion 320 of the housing in the follow sub-steps.

[0136] In step 522, the inner housing portion 320 is provided on a spindle such that the spindle is received within the conduit. A spindle is a rotatable support member for supporting a 21 P005146-W001 component, for example the inner housing portion, such that the component may be rotated. Spindles may be used, for example, in lathes.

[0137] In step 524, a first end of the electrode assembly 200 is affixed to the inner housing portion 320, when supported on the spindle, and in step 526 the spindle is rotated, thereby rotating the inner housing portion 320 received on the spindle and winding the electrode assembly 200 onto the inner housing portion 320.

[0138] The electrode assembly 200 is therefore wound directly onto a component of the hollow cell 100, which is not removed from the middle of the wind of the electrode assembly as would otherwise be necessary in conventional electrode assembly winding techniques.

[0139] After the electrode assembly 200 has been wound around the elongate tubular portion 322 of the inner housing portion 320, the inner housing portion 320 is removed from the spindle.

[0140] The method 500 may then progress to steps 530 and 540, which may be performed in sequence or simultaneously, and the first tab portion 210 of the electrode assembly 200 is clamped to the flange 324 or the first exposed portion 322a of the inner housing portion 320 using a first clamping member in step 530. In step 540, the second tab portion 220 is clamped to the conductive support member 338 using a second clamping member, for example a slip ring 360.

[0141] The method 500 may then progress to step 550 in which the outer housing portion 350 is provided over the electrode assembly 200 and the inner housing portion 320 such that the electrode assembly 200 is provided between the outer housing portion 350 and the inner housing portion 320.

Claims

22 P005146-W001CLAIMS1. A hollow cell comprising: an electrode assembly; and a housing containing the electrode assembly, the housing defining a conduit extending entirely therethrough, wherein the electrode assembly is arranged around the conduit.

2. The hollow cell claimed in claim 1, wherein the electrode assembly surrounds a perimeter of the conduit.

3. The hollow cell claimed in any of claims 1 to 2, wherein the housing comprises a first terminal provided at a first end of the housing and a second terminal provided at a second end of the housing, opposite the first end of the housing, and wherein the conduit extends through the first terminal and the second terminal such that the first terminal and the second terminal surround the conduit.

4. The hollow cell claimed in claim 3, wherein the electrode assembly is electrically connected to the first terminal and the second terminal.

5. The hollow cell claimed in any of claim 3 to 4, wherein the second terminal is proportioned to be receivable within the first terminal.

6. The hollow cell claimed in any of claims 1 to 5, wherein the housing comprises: an outer housing portion; and an inner housing portion, wherein the inner housing portion defines the conduit extending through the housing, and wherein the electrode assembly is provided between the outer housing portion and the inner housing portion.23 P005146-W0017. The hollow cell claimed in claim 6, when dependent directly or indirectly on claim 3, wherein a first end of the inner housing portion forms at least part of the first terminal, and wherein a second end of the inner housing portion, opposite the first end of the inner housing portion, forms at least part of the second terminal.

8. The hollow cell claimed in any of claims 6 to 7, wherein the inner housing portion comprises: a conduit insulation layer, wherein the conduit insulation layer has a conduit surface facing the conduit; an inner internal insulation layer, wherein the inner internal insulation layer has an inner insulation surface facing the electrode assembly; and an inner conductive layer provided between the conduit insulation layer and the inner internal insulation layer.

9. The hollow cell claimed in claim 8, wherein the inner conductive layer comprises: an elongate tubular portion, wherein the conduit extends through the elongate tubular portion; and a flange circumscribing a first end of the elongate tubular portion, and wherein the flange forms at least part of the first terminal.

10. The hollow cell claimed any of claims 7 to 9, wherein the inner housing portion further comprises a conductive support member provided at the second end of the inner housing portion, wherein the conductive support member forms at least part of the second terminal.

11. The hollow cell claimed in claim 10, when dependent directly or indirectly on claim 9, wherein the conductive support member is received within the elongate tubular portion of the inner conductive layer and electrically isolated from the inner conductive layer by the conduit insultation layer.

12. The hollow cell claimed in any of claims 6 to 11, wherein the outer housing portion comprises:24 P005146-W001 an outer conductive layer; an outer internal insulation layer provided on an inner surface of the outer conductive layer and having an outer insulation layer surface facing the electrode assembly.

13. The hollow cell claimed in claim 11, when dependent directly or indirectly on claim 7, wherein the outer conductive layer is electrically connected to the first terminal and electrically isolated from the second terminal.

14. The hollow cell claimed in any preceding claim, wherein the electrode assembly comprises: a first electrode layer; a second electrode layer; a middle separator layer provided between the first electrode layer and the second layer.

15. The hollow cell claimed in claim 14, when dependent directly or indirectly on claim 3, wherein the first electrode layer comprises a first tab portion protruding from a first end of the electrode assembly for contacting the first terminal, and wherein the second electrode layer comprises a second tab portion protruding from a second end of the electrode assembly for contacting the second terminal.

16. The hollow cell claimed in claim 15, when dependent directly or indirectly on claim 9, wherein the housing further comprises a first clamping member for clamping the first tab portion of the first electrode layer to the flange.

17. The hollow cell claimed in any of claims 15 to 16, when dependent directly or indirectly on claim 10, wherein the housing comprises a second clamping member for clamping the second tab portion of the second electrode layer to the conductive support member.25 P005146-W00118. The hollow cell claimed in claim 17, wherein the second clamping member is a slip ring adapted to fit over the conductive support member to clamp the second tab portion between the second clamping member and the conductive support member.

19. A hollow battery comprising a plurality of hollow cells as claimed in any preceding claim, arranged such that a first hollow cell of the plurality of hollow cells is electrically connected to a second hollow cell of the plurality of hollow cells.

20. A hollow battery as claimed in claim 19, when dependent directly or indirectly on claim 5, arranged such that the second terminal of the first hollow cell is received within the first terminal of the second hollow cell.

21. A method of manufacturing a hollow cell comprising a housing defining a conduit extending entirely therethrough, the method comprising: providing an electrode assembly around the conduit defined by the housing.

22. The method claimed in claim 21, wherein the housing comprises an inner housing portion defining the conduit extending through the housing, and wherein providing the electrode assembly around the conduit comprises: providing the electrode assembly about the inner housing portion of the housing.

23. The method claimed in claim 22, wherein providing the electrode assembly about the inner housing portion comprises: arranging the inner housing portion on a spindle such that the spindle is received within the conduit; affixing a first end of the electrode assembly to the inner housing portion; and rotating the spindle, thereby rotating the inner housing portion received on the spindle and winding the electrode assembly onto the inner housing portion.

24. The method claimed in claim 22 or 23, wherein an inner conductive layer of the inner housing portion comprises:26 P005146-W001 an elongate tubular portion, wherein the conduit extends through the elongate tubular portion; a flange circumscribing a first end of the elongate tubular portion, and wherein the flange forms at least part of the first terminal, and wherein the inner housing portion further comprises a conductive support member provided at a second end of the inner housing portion, opposite the first end of the inner housing portion, and wherein the conductive support member forms at least part of the second terminal, and wherein the electrode assembly comprises: a first electrode layer comprising a first tab portion protruding from a first end of the electrode assembly; a second electrode layer comprising a second tab portion protruding from a second end of the electrode assembly, opposite the first end of the electrode assembly; and a middle separator layer provided between the first electrode layer and the second layer; and wherein the method further comprises: clamping the first tab portion to the flange using a first clamping member; and clamping the second tab portion to the conductive support member using a second clamping member.

25. The method claimed in any of claims 22 to 24, wherein the hollow cell further comprises an outer housing portion, and wherein the method further comprises: providing the outer housing portion over the electrode assembly and the inner housing portion such that the electrode assembly is provided between the outer housing portion and the inner housing portion.

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