Magnetic field generator

Abstract

There is provided a magnetic field generator comprising an electromagnet for generating a magnetic field upon supply of electric current thereto and electric circuitry connected to the electromagnet and connectable to a power supply The magnetic field generator further comprises a printed circuit board, PCB, wherein either or both of the electromagnet and the electric circuitry are provided as part of the PCB as one or more electrically conductive traces.

Description

[0001] MAGNETIC FIELD GENERATOR

[0002] Field of the Invention

[0003] The present invention relates to magnetic field generators and particularly, although not exclusively, to magnetic field generators for integration with electrochemical systems.

[0004] Background

[0005] Electrochemical systems (such as systems comprising electrochemical cells) can be upgraded to magneto-electrochemical systems through the application of a magnetic field. The magnetic field can be produced by magnetic field sources such as one or more electromagnets.

[0006] The integration of magnetic field sources in an electrochemical system can be challenging, for example, due to the need to provide magnetic field sources and electric circuitry in a way that ensures even / consistent exposure of the electrochemical components to the generated magnetic field.

[0007] The present invention has been devised in light of the above considerations.

[0008] Summary of the Invention

[0009] In a first aspect, there is provided a magnetic field generator comprising: an electromagnet for generating a magnetic field upon supply of electric current thereto; electric circuitry connected to the electromagnet and connectable to a power supply; and a printed circuit board, PCB, wherein either or both of the electromagnet and the electric circuitry are provided as part of the PCB as one or more electrically conductive traces.

[0010] In this way, the PCB can be used to encapsulate the electric circuitry and / or the electromagnet to facilitate integration of the magnetic field generator with an electrochemical system. For example, providing the electric circuitry as part of the PCB can facilitate routing of the electric circuitry relative to the electromagnet, and e.g. relative to components of the electrochemical system.

[0011] Providing both the electromagnet and the electric circuitry as part of the PCB can ensure that the magnetic field generator is a unitary, monolithic component which can improve its ease of integration and replaceability.

[0012] The power supply may be configured to supply electric current to the electromagnet.

[0013] Typically, PCBs have planar surfaces spaced by a thickness of the PCB. Electrical components are typically mounted to one or both planar surfaces of the PCB. 008877904 2

[0014] The electrically conductive traces providing either or both of the electromagnet and the electric circuitry may be provided on a surface of the PCB, or within the PCB. In some examples, the electromagnet and / or the electric circuitry may extend along the thickness of the PCB.

[0015] The electrically conductive traces providing the electromagnet and / or the electric circuitry may be arranged in a circular or polygonal (e.g. square, rectangular, hexagonal or octagonal) manner.

[0016] The thickness and / or density of the electrically conductive traces providing the electromagnet may be selected according to application requirements to achieve a desired magnetic field strength.

[0017] Typically, an electromagnet may comprise one or more turns. In some examples, the turns may be coplanar. For example, the turns may be nested relative to one another, in the same plane.

[0018] In some examples, the turns may be mutually spaced along the thickness of the PCB.

[0019] The turns may be electrically connected to one another, in series or in parallel. The turns may be electrically connected to one another through electrically conductive traces and / or vias of the PCB. The electrically conductive traces may connect turns extending along the same plane of the PCB. The electrically conductive vias may connect turns which are spaced relative to one another along the thickness of the PCB. In other words, the electrically conductive vias may extend through the thickness of the PCB to electrically connect turns spaced along the thickness of the PCB.

[0020] The magnetic field generator may comprise a plurality of electromagnets. Each electromagnet may be electrically connected to the same electric circuitry, or to a respective different electric circuitry connectable to a power supply.

[0021] The PCB may comprise a plurality of layers. The layers may be stacked along the thickness of the PCB.

[0022] The layer density may vary according to application and / or manufacturer requirements. In some examples, the layer density of the PCB may be at least 1 layer per millimetre, or at least 2 layers per millimetre, or at least 5 layers per millimetre, or at least 10 layers per millimetre, or at least 20 layers per millimetre. In some examples, the layer density of the PCB may be 50 layers per millimetre or less, or 25 layers per millimetre or less, or 20 layers per millimetre or less, or 15 layers per millimetre or less, or 10 layers per millimetre or less, or 5 layers per millimetre or less.

[0023] At least some of the layers (e.g. each layer) of the PCB may comprise a respective electromagnet completely contained within said layer (i.e. not extending across multiple layers). In some examples, different PCB layers may comprise a plurality of respective electromagnets completely contained within said layer (i.e. not extending across multiple layers).

[0024] The electromagnets provided as part of respective different layers of the PCB may overlay one another (along the thickness of the PCB). For example, the electromagnets provided on respective different layers of the PCB may be arranged coaxially as to fully overlay one another. Alternatively, the electromagnets provided as part of respective different layers of the PCB may be arranged in a staggered manner so as to partially overlay one another. 008877904 3

[0025] In some examples, at least some of the layers (e.g. each layer) of the PCB may comprise a respective different portion of the same electromagnet. For example, different PCB layers may comprise one or more turns of the same electromagnet. Increasing the number of layers (by increasing the layer density and / or the thickness) of the PCB can thus increase the number of turns of the electromagnet. The electromagnet portions (e.g. turns) provided on respective different layers of the PCB may be electrically connected by electrically conductive vias extending along the thickness of the PCB.

[0026] The magnetic field generator may comprise one or more thermal management layers. In some examples, the one or more thermal management layers may be part of the PCB.

[0027] In some examples, the one or more thermal management layers may comprise no electrically conductive components, e.g. traces.

[0028] In some examples, the one or more thermal management layers may be sandwiched between PCB layers comprising electrical components (such as electrically conductive traces / vias). In other examples, the thermal management layers may sandwich PCB layers comprising electrical components (such as electrically conductive traces / vias).

[0029] In some examples, the magnetic field generator may comprise at least one thermally conductive thermal management layer. For example, the / each thermally conductive thermal management layer may have a thermal resistance of at least 0.1 °C / W, or at least 0.25 °C / W, or at least 0.5 °C / W, or at least 0.75 °C / W. The / each thermally conductive thermal management layer may have a thermal resistance of less than 1 °C / W, or less than 0.75 °C / W, or less than 0.5 °C / W, or less than 0.25 °C / W. One or more of the thermally conductive thermal management layers may have a thermal conductivity of at least 1 W / mK, or at least 1 .05 W / mK such as around 1 .059 W / mK, or at least 1.1 W / mK.

[0030] In some examples, the magnetic field generator may comprise at least one thermally insulating thermal management layer. For example, the / each thermally insulating thermal management layer may have a thermal resistance of 0.1 °C / W or less, or 0.075 °C / W or less, or 0.05 °C / W or less, or 0.025 °C / W or less. The / each thermally insulating thermal management layer may have a thermal resistance of at least 0.01 °C / W, or at least 0.025 °C / W, or at least 0.05 °C / W, or at least 0.075 °C / W. One or more of the thermal management layers may have a thermal conductivity of less than 1 W / mK, or less than 0.75 W / mK, or less than 0.5 W / mK, such as around 0.343 W / mK.

[0031] In some examples, the magnetic field generator may comprise a combination of thermally insulating and thermally conductive thermal management layers, such as one or more thermally insulating thermal management layers and one or more thermally conductive thermal management layers. In some examples, the thermally insulating layer(s) may be alternately arranged relative to the thermally conductive layer(s).

[0032] In some examples, the magnetic field generator may comprise a pair of thermally conductive thermal management layers and a thermally insulating thermal management layer. The thermally conductive thermal management layers may sandwich the thermally insulating thermal management layer, i.e. the thermally insulating thermal management layer may be interposed between (and e.g. parallel to) the thermally conductive thermal management layers. The thermally conductive thermal management layers 008877904 4 may define opposite outer surfaces of the magnetic field generator, for example in plane perpendicular to the thickness of the PCB. Each thermally conductive thermal management layer and the thermally insulating thermal management layer may sandwich respective one or more layers comprising electrically conductive components, such as traces. The one or more layers comprising electrically conductive components may be layer(s) defining one or more electromagnets and / or portions thereof.

[0033] This arrangement may be advantageous as the thermally conductive thermal management layers may help homogenise thermal distribution within one or more electrochemical cells provided in thermal communication with said magnetic field generator, e.g. as discussed with reference to the second aspect below. The thermally insulating thermal management layer may improve inter-cell thermal distribution uniformity between different electrochemical cells provided in thermal communication with the magnetic field generator, e.g. as described with reference to the second aspect below.

[0034] At least one of the one or more thermal management layers may be arranged to provide a surface (i.e. outer surface) of the magnetic field generator, for example in plane perpendicular to the thickness of the PCB.

[0035] At least one of the one or more thermal management layers may be arranged to provide a surface of the magnetic field generator, the surface being a surface of the magnetic field generator with the largest surface area out of all surfaces of the magnetic field generator. In this way, heat exchange between the magnetic field generator and its neighbouring electrochemical cell(s) can be improved.

[0036] In some examples, the magnetic field generator may comprise at least one thermally conductive thermal management layer and at least one thermally insulating thermal management layer. The thermally conductive thermal management layer may be opposite the thermally insulating thermal management layer. The thermally conductive and thermally insulating thermal management layers may define opposite surfaces of the magnetic field generator. In other words, the thermally conductive and thermally insulating thermal management layers may sandwich the remaining layer(s) of the PCB, e.g. the layer(s) comprising electrically conductive components, such as traces. The thermally insulating thermal management layer may be parallel to the thermally conductive thermal management layer.

[0037] The electromagnet may be configured to generate a changing magnetic field. The changing magnetic field may vary overtime in direction, and / or magnitude, and / or frequency.

[0038] The changing magnetic field may be rotating, pulsed, oscillating, or any combination thereof.

[0039] The changing magnetic field may have a frequency of at least 0.1 Hz, or at least 1 Hz, or at least 10 Hz, or at least 20 Hz or at least 50 Hz, or at least 75Hz, or at least 100 Hz, or at least 125 Hz. Alternatively, or in addition, the changing magnetic field p may have a frequency of 500 Hz or less, or 250 Hz or less, or 150 Hz or less, or 100 Hz or less, or 50 Hz or less, or 25 Hz or less, or 15 Hz or less, or 10 Hz or less, or 5Hz or less, or 1 Hz or less.

[0040] The electromagnet may be configured to generate a magnetic field having a magnitude of at least 1 mT, or at least 10 mT, or at least 50 mT, or at least 100 mT, or at least 250 mT, or at least 500 mT. The 008877904 5 electromagnet may be configured to generate a magnetic field having a magnitude of 1000 mT or less, or 500 mT or less, or 250 mT or less, or 100 mT or less, or 50 mT or less, or 10 mT or less.

[0041] The PCB may be rigid or flexible. The PCB may be single- or double-sided. The PCB may be a high- density interconnect PCB (with e.g. buried via, microvia and / or stacked microvia).

[0042] The PCB may be manufactured using standard PCB manufacturing processes.

[0043] The electrically conductive traces and / or vias may be formed of an electrically conductive metal, such as copper.

[0044] In a second aspect, there is provided a magneto-electrochemical system comprising: a magnetic field generator according to the first aspect; and one or more electrochemical cells; wherein the magnetic field generator is in thermal communication with the one or more electrochemical cells and the magnetic field generator is arranged such that the magnetic field generated by the magnetic field generator permeates the one or more electrochemical cells.

[0045] That is, the magnetic field generator may be arranged / located relative to the one or more electrochemical cell(s) so as to transfer heat thereto via convection, conduction, and / or radiation, in addition to generating a magnetic field which permeates the cell(s) for electrochemical benefit.

[0046] In this way, the magnetic field generator can expose the one or more electrochemical cells to a magnetic field, which is known to improve cell performance (e.g. ion transport), and at the same perform thermal management on the one or more electrochemical cells by exchanging heat therewith. In other words, the magnetic field generator can advantageously perform a dual function of magnetic field generation and heat management.

[0047] In some examples, the magneto-electrochemical system may comprise a plurality of magnetic field generators according to the first aspect. The magneto-electrochemical system may comprise a plurality of electrochemical cells. The magnetic field generators may be arranged so as to sandwich the electrochemical cells. The magnetic field generators may be arranged in an alternate manner with the electrochemical cells, e.g. such that each electrochemical cell is sandwiched between a respective pair of magnetic field generators, or such that each magnetic field generator is sandwiched between a respective pair of electrochemical cells.

[0048] The magnetic field generator(s) may be in direct contact with the electrochemical cells. For example, the / each magnetic field generator may be arranged to abut an outer (planar or curved) surface of a respective electrochemical cell. Alternatively, the magnetic field generator(s) may be spaced from the electrochemical cells, e.g. by airgaps.

[0049] In some examples, the / each magnetic field generator may be arranged to surround at least a part of a respective electrochemical cell. For example, the / each magnetic field generator may be arranged to contour an outer (e.g. curved) surface of a respective electrochemical cell. The / each magnetic field generator may be wrapped around a respective electrochemical cell. For example, the / each magnetic field generator may be wrapped around the outer (tubular) surface of a cylindrical electrochemical cell. 008877904 6

[0050] To this end, the PCB of the magnetic field generator is a flexible PCB bendable to contour an outer curved surface of an electrochemical cell.

[0051] As described with reference to the fist aspect, the / each magnetic field generator may comprise one or more thermal management layers, e.g. thermally conductive and / or thermally insulating thermal management layers.

[0052] The provision of thermally conductive layer(s) may help homogenise thermal distribution across the cell(s), thereby reducing occurrence of hotspots on the electrochemical cells. Additionally, the provision of thermally conductive thermal management layer(s) can help cool the electrochemical cells to reduce risk of overheating.

[0053] The provision of thermally insulating thermal management layer(s) may help reduce thermal runaway between the electrochemical cells. Additionally, it may also help store useful heat generated by the electrochemical cells, which can help enhance the reaction kinetics in the cells.

[0054] Furthermore, as discussed above, the / each magnetic field generator may comprise at least one thermally conductive thermal management layer and at least one thermally insulating thermal management layer defining opposite surfaces of the magnetic field generator. In this case, the thermally conductive thermal management layer may facilitate heat exchange with its neighbouring (e.g. first) electrochemical cell, whereas the opposed thermally insulating thermal management layer may help prevent heat from the first electrochemical cell propagating to a (second) electrochemical cell neighbouring the thermally insulating thermal layer. In this example, the first and second electrochemical cell may sandwich said magnetic field generator, with the first electrochemical cell being proximal the thermally conductive thermal management layer and distal the thermally insulating thermal management layer, and the second electrochemical cell being proximal the thermally insulating thermal management layer and distal the thermally conductive thermal management layer.

[0055] Each electrochemical cell may be a battery. Each electrochemical cell may be a positive ion battery and the current flow path may be the direction of travel of positive ions. Alternatively, each electrochemical cell may be a negative ion battery and the current flow path may be the direction of travel of negative ions. Each electrochemical cell may be a lithium-ion battery. Each electrochemical cell may be a solid- state battery. Each electrochemical cell may be cylindrical cell, a pouch cell, or a prismatic cell.

[0056] The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

[0057] Summary of the Figures

[0058] Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which:

[0059] Figure 1 shows a known assembly comprising an electromagnet and electric circuitry. 008877904 7

[0060] Figures 2A and 2B respectively show example implementations of a magnetic field generator according to the present disclosure.

[0061] Figures 3A, 3B and 3C respectively show example implementations of a magnetic field generator according to the present disclosure.

[0062] Figures 4A, 4B and 4C respectively show example implementations of a magnetic field generator according to the present disclosure.

[0063] Figures 5A and 5B respectively show example implementations of a magnetic field generator according to the present disclosure.

[0064] Figure 6A, 6B and 6C respectively show example implementations of a magneto-electrochemical system according to the present disclosure.

[0065] Figure 7A, 7B, 7C, 7D, and 7E respectively show example implementations of a magnetoelectrochemical system according to the present disclosure.

[0066] Figures 8A and 8B show respective different views of a magneto-electrochemical system according to the present disclosure.

[0067] Detailed Description of the Invention

[0068] Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

[0069] Figure 1 shows a conventional electromagnet 10’ connected to electric circuitry 20’ for connection to a power supply (not shown). During operation, electric current is supplied to the electromagnet 10’ from the power supply, via the electric circuitry 20’. This causes the electromagnet 10’ to generate a magnetic field. The electromagnet 10’ and electric circuitry 20’ can be integrated with an electrochemical system to upgrade the electrochemical system to a magneto-electrochemical system. However, as discussed above, such integration can be challenging.

[0070] According to the present disclosure, there is provided a magnetic field generator 100 comprising an electromagnet 10 and electric circuitry 20 electrically connected to the electromagnet 20 and electrically connectable to a power supply (not shown). The magnetic field generator 100 further comprises a printed circuit board (PCB) 14. In this example, the electromagnet 10 is configured to generate a changing magnetic field.

[0071] As shown for example in Figures 2A and 2B, each or both of the electromagnet 10 and the electric circuitry 20 can be provided as part of the PCB 14, as one or more electrically conductive traces. Specifically, in the example of Figure 2A only the electrical circuitry 20 is provided on the PCB 14 using electrically conductive traces (e.g. made of copper), while in the example of Figure 2A, both the electromagnet 10 and the electric circuitry 20 are provided on the PCB 14 using electrically conductive traces. In both examples, the electromagnet 10 comprises a plurality of turns. 008877904 8

[0072] The PCB 14 can comprise a plurality of layers 12 stacked along its thickness z as shown in Figures 3A- 3C. In the examples of Figures 3A-3C, each PCB layer 12 comprises a respective different portion (turn) of the same electromagnet 10. The different portions are electrically connected through electrically conductive vias (not shown) extending through the thickness of the PCB 14. The number of portions (turns) of the electromagnet 10 can be increased by increasing the thickness of the PCB 14, as shown in Figure 3B, or by increasing the layer density of the PCB 14, as shown in Figure 3C. In some examples, the layer density may be around 10 layers per 1 mm, but it can be varied as desired, depending on the application.

[0073] It is also possible that different layers 12 of the PCB 14 comprise respective different electromagnets 10. This is discussed with reference to Figures 4A-4C.

[0074] In the example of Figure 4A, each layer 12 of the PCB 14 comprises a respective electromagnet 10. The electromagnet 10 has a plurality of turns nested relative to one another in the same plane. The plurality of turns are provided by electrically conductive traces arranged in a rectangular manner on the PCB 14.

[0075] The PCB has three layers 12, as shown on the right-hand side of Figure 4A. When the layers 12 are stacked along the thickness z, the electromagnets 10 are co-axially arranged and fully overlay one another along the thickness z.

[0076] In the example of Figure 4B, each layer 12 of the PCB comprises a plurality of (i.e. four) respective different electromagnets 10 of the same type as shown in Figure 4A. As in the example of Figure 4A, the electromagnets 10 provided on respective different layers 12 of the PCB 14 are also coaxially arranged and fully overlay one another along the thickness z.

[0077] In the example of Figure 4C, each layer 12 of the PCB 14 comprises a respective different electromagnets 10 of the same type as shown in Figure 4A. However, in this case, the electromagnets 10 provided on respective different layers 12 of the PCB 14 are staggered such that they partially overlay one another along the thickness z.

[0078] In some examples, the magnetic field generator 100 also comprises thermal management layers 18. This is shown in the examples of Figures 5A and 5B where in addition to the electromagnet 10 and the electric circuitry 20, the PCB 14 comprises one or more thermal management layers 18. The thermal management layer(s) 18 in this example do not comprise any electrically conductive components, e.g. electrically conductive traces.

[0079] In the example of Figure 5A, the thermal management layer 18 is sandwiched between layers 12 of the PCB 14 containing electrically conductive traces. In the example of Figure 5B, a pair of thermal management layers 18 sandwich the PCB layers 12 containing the electrically conductive traces. Thus, in the example of Figure 5B, the thermal management layers 18 provide opposite surfaces of the magnetic field generator 100, which are spaced along the thickness z of the PCB 14.

[0080] The thermal management layers 18 can be thermally conductive 18a or thermally insulating 18b.

[0081] The / each thermally conductive 18b thermal management layer may have a thermal resistance between 0.1 °C / W and 1 °C / W. The / each thermally conductive thermal management layer 18b may a thermal 008877904 9 conductivity of at least 1 .05 W / mK such as around 1 .059 W / mK. The / each thermally insulating thermal management layer 18a may have a thermal resistance between 0.01 °C / W and 0.1 °C / W. The / each thermally insulating thermal management layer 18a may have a thermal conductivity of less than 0.5 W / mK, such as around 0.343 W / mK.

[0082] Next, Figures 6A-6C show example implementations of a magneto-electrochemical system 200 according to the present disclosure.

[0083] The magneto-electrochemical system 200 of Figure 6A comprises a pair of magnetic field generators 100 sandwiching an electrochemical cell 30. As described with reference to Figures 5A-5B, the magnetic field generators 100 comprises one or more thermal management layers 18. The components of each of the magnetic field generators 100, i.e. its electromagnet(s) 10, its electric circuitry 20, and its thermal management layer(s) 18 are provided on the same respective PCB 14. As such, the magnetic field generators 100 are a unitary, monolithic devices.

[0084] In the example of Figure 6B, the magneto-electrochemical system 200 comprises a plurality of magnetic field generators 100 and a plurality of electrochemical cells 30 arranged in an alternate manner such that each magnetic field generator 100 is sandwiched between a respective pair of electrochemical cells 30.

[0085] In the example of Figure 6C, the magneto-electrochemical system 200 comprises a pair of magnetic field generators 100 sandwiching a plurality of electrochemical cells 30.

[0086] In all examples, the magnetic field generator(s) is / are in thermal communication with the electrochemical cells 30, and at the same time, the magnetic field generated by the magnetic field generator(s) permeates the electrochemical cells 30. In these examples, the electrochemical cells 30 are not in direct contact with the magnetic field generators) 100 but are spaced therefrom by airgaps.

[0087] Figures 7A-7E show further example implementations of a magneto-electrochemical system 200 according to the present disclosure. In the example of the Figure 7A, a pair of electrochemical cells 30 sandwiches a magnetic field generator 100 as described with reference to Figures 6A-6C. As above, the magnetic field generator 100 is in thermal communication with the electrochemical cells 30, and furthermore, the magnetic field generated by the magnetic field generator 100 permeates the electrochemical cells 30 in use to enhance their performance.

[0088] In the examples of Figures 7B and 7C, the magnetic field generator 100 is in direct contact (and therefore in thermal communication) with the electrochemical cell 30. In this example, the magnetic field generator 100 comprises one or more thermally insulating thermal management layers 18a. The thermally insulating thermal management layers 18a cause the magnetic field generator 100 to act as a thermal insulator between the electrochemical cells 30. Thus, the magnetic field generator 100 in the examples of Figures 7B and 7C prevents or reduces heat exchange between the electrochemical cells 30. As shown in Figure 7C, this enables one of the electrochemical cells 30 to be at a higher temperature than the other electrochemical cell. Thus, the magnetic field generator 100 can mitigate thermal runaway, allowing individual cell temperature regulation and isolation e.g. during venting as shown in Figure 7C. 008877904 10

[0089] Figure 7D and 7E show a further example implementation of a magneto-electrochemical system 200 according to the present disclosure. As shown in Figure 7D, the magneto-electrochemical system 200 comprises a plurality of (i.e. three) electrochemical cells arranged alternately with a plurality of (i.e. two) magnetic field generators 100. Each magnetic field generator 100 is sandwiched between a respective pair of electrochemical cells 30.

[0090] With reference to Figure 7E, each magnetic field generator 100 comprises a pair of thermally conductive thermal management layers 18b defining opposite outer surfaces of the magnetic field generator in planes perpendicular to the thickness of the PCB 14, and a thermally insulating layer 18a sandwiched between the thermally conductive thermal management layers 18b. The provision of thermally conductive layers 18b can help homogenise thermal distribution within the cells 30, thereby reducing occurrence of hotspots on the electrochemical cells 30, as well as help cool the electrochemical cells 30 to reduce risk of overheating. The thermally insulating thermal management layer 18a may improve inter-cell thermal distribution uniformity between different electrochemical cells 30 provided in thermal communication with the magnetic field generator 100.

[0091] Each thermally conductive thermal management layer 18b and the thermally insulating thermal management layer 18a together sandwich one or more layers 12 of the PCB 14 comprising electrically conductive components, such as traces, which provide one or more electromagnets 10 and / or portions thereof.

[0092] In an alternative example implementation, not shown in the figures, the magnetic field generator 100 may comprise at least one thermally conductive thermal management layer 18b and at least one thermally insulating thermal management layer 18a defining opposite surfaces of the magnetic field generator 100. In this case, the thermally conductive thermal management layer 18 may facilitate heat exchange with its neighbouring (e.g. first) electrochemical cell 30, whereas the opposed thermally insulating thermal management layer 18 may help prevent heat from the first electrochemical cell propagating to a (second) electrochemical cell 30 neighbouring the thermally insulating thermal layer.

[0093] Finally, Figures 8A and 8B show different views of a magneto-electrochemical system 200 comprising a cylindrical electrochemical cell 30 and a magnetic field generator 30. The magnetic field generator 100 is arranged to surround and abut (i.e. be in direct contact with) the outer tubular surface of the cylindrical cell. In other words, the magnetic field generator 100 is wrapped around the cylindrical electrochemical cell 30, thereby contouring its outer tubular surface. To this end, the PCB 14 of the magnetic field generator 100 is a flexible PCB, using standard flexible PCB materials, the flexibility chosen such that the magnetic field generator is capable of contouring the outer curved (i.e. tubular) surface of the cylindrical electrochemical cell.

[0094] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof. 008877904 11

[0095] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0096] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0097] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0098] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0099] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / - 10%.

Claims

008877904 12Claims:1 . A magnetic field generator comprising: an electromagnet for generating a magnetic field upon supply of electric current thereto; electric circuitry connected to the electromagnet and connectable to a power supply; a printed circuit board, PCB, wherein either or both of the electromagnet and the electric circuitry are provided as part of the PCB as one or more electrically conductive traces.

2. The magnetic field generator of claim 1 , wherein the PCB comprises a plurality of layers.

3. The magnetic field generator of claim 2 wherein at least some of the plurality of layers of the PCB comprise respective different portions of the same electromagnet.

4. The magnetic field generator of claim 2 wherein at least some of the plurality of layers of the PCB each comprise one or more electromagnets completely contained within said layer.

5. The magnetic field generator of any one of the preceding claims wherein the magnetic field generator comprises a plurality of electromagnets.

6. The magnetic field generator of claim 5 wherein the one or more electromagnets provided on different layers of the PCB are arranged co-axially so as to fully overlay one another.

7. The magnetic field generator of claim 5 wherein the one or more electromagnets provided on different layers of the PCB are staggered so as to partially overlay one another.

8. The magnetic field generator of any one of the preceding claims wherein the magnetic field generator comprises one or more thermal management layers.

9. The magnetic field generator of claim 8 wherein the PCB comprises the one or more thermal management layers.

10. The magnetic field generator of claim 8 or 9 wherein at least one of the one or more thermal management layer provides a surface of the magnetic field generator.11 . The magnetic field generator of any one of claims 8 to 10, wherein at least one of the one or more thermal management layers is thermally conductive.

12. The magnetic field generator of claim 11 wherein the at least one thermally conductive thermal management layer has a thermal resistance between 0.1 °C / W and 1 °C / W.

13. The magnetic field generator of any one of claims 8 to 12, wherein at least one of the one or more thermal management layers is thermally insulating.008877904 1314. The magnetic field generator of claim 13 wherein the at least one thermal insulating thermal management layer has a thermal resistance between 0.01 °C / Wand 0.1 °C / W.

15. The magnetic field generator of any one of claims 8 to 14 wherein the magnetic field generator comprises at least one thermally conductive thermal management layer and at least one thermally insulating thermal management layer.

16. The magnetic field generator of claim 15 wherein the at least one thermally conductive thermal management layer and the at least one thermally insulating thermal management layer define respective opposite surfaces of the magnetic field generator.

17. The magnetic field generator of claim 15 or 16 wherein the one or more thermally conductive thermal management layers are arranged alternately relative to the one or more thermally insulating thermal management layers.

18. The magnetic field generator of any one of the preceding claims wherein the generated magnetic field is between 1 mT and 1000 mT19. The magnetic field generator of any one of the preceding claims wherein the generated magnetic field is a changing magnetic field.

20. A magneto-electrochemical system comprising: a magnetic field generator according to any one of the preceding claims; and one or more electrochemical cells; wherein the magnetic field generator is in thermal communication with the one or more electrochemical cells and the magnetic field generator is arranged such that the magnetic field generated by the magnetic field generator permeates the one or more electrochemical cells.21 . The magneto-electrochemical system of claim 20 wherein the magneto-electrochemical system comprises a plurality of magnetic field generators and a plurality of electrochemical cells, the magnetic field generators being arranged in an alternate manner with the electrochemical cells.

22. The magneto-electrochemical system of claim 21 wherein each electrochemical cell is sandwiched between a respective pair of magnetic field generators.

23. The magneto-electrochemical system of any one of claims 20 to 22 wherein the magnetic field generator is arranged to surround at least a part of a respective electrochemical cell.

24. The magneto-electrochemical system of any one of claims 20 to 23 wherein the / each electrochemical cell is one of: a cylindrical cell, a pouch cell, and a prismatic cell.008877904 1425. The magneto-electrochemical system of claim 24 wherein the magnetic field generator is wrapped around an outer tubular surface of an electrochemical cell which is cylindrical cell.

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