Patent ID: 12224410

DETAILED DESCRIPTION OF THE INVENTION

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.

Generally, a magnetic field source, such as a permanent magnet, a temporary magnet or an electromagnet produces a field which can be represented by magnetic field lines. This physical phenomenon is discussed with respect toFIGS.1A-1B. Specifically,FIG.1Ashows a magnetic field source6having a south pole S and a north pole N which produces a magnetic field represented by magnetic field lines7. Similarly,FIG.1Bshows two magnetic field sources6of the type ofFIG.1Aarranged such that the south pole S of the first magnetic field source is proximal the north pole N of the second magnetic field source. This arrangement of magnetic field sources6produces a total magnetic field which is represented by respective magnetic field lines7. Thus, the magnetic fields produced by magnetic field sources which are sufficiently close in space, interact with one another and thus produce a total magnetic field. The present invention relies at least in part on this phenomenon.

The present invention provides a magnetic flux generator comprising one or more magnetic field sources, each being configured to produce a respective magnetic field which is individually controllably variable in three spatial dimensions. The magnetic flux generator generates a total changing magnetic field which is provided by the one or more magnetic fields together. Each magnetic field may be individually controllably varied over time continuously or incrementally over time.

A first embodiment of the invention is discussed with reference toFIG.2.FIG.2schematically shows a magnetic flux generator1and a flat electrochemical cell2. The magnetic flux generator1comprises a plurality of magnetic field sources6which are arranged in a common plane and supported by a planar (i.e. flat) mechanical support8. The magnetic field sources6are arranged in a grid, but other arrangements are also possible.

In this example, the plurality of magnetic fields sources6is a plurality of electromagnets. Each electromagnet comprises a coil of wire wound around a core (e.g. a metal core, such as a ferromagnetic core, or an air core provided by an air-filled space at the centre of the electromagnet). Each electromagnet6is configured to be coupled to an electrical power source (not shown) via electrical connections9to generate its respective magnetic field. Controlling each electromagnet may involve varying the amount of electrical power and/or the direction of the electrical current supplied thereto by the electrical power source. For example, it may be desirable to switch one or more of the electromagnets off (i.e. supply no power to them) to vary the total changing magnetic field generated by the magnetic flux generator1. Additionally, or alternatively, it may be desirable to provide electrical current having different directions to respective different electromagnets to vary the magnetic polarity (i.e. north N or south S) of the respective generated magnetic fields.

The electrochemical cell2is a flat electrochemical cell which may be a prismatic cell or a pouch cell. In this example, the flat electrochemical cell is a pouch cell comprising a housing5(whose floor is shown inFIG.2), a pair of electrodes13defining a current flow path and spaced by electrolyte12, and a pair of tabs4. The electrodes13and the electrolyte12(shown, e.g. inFIGS.6A and6B) together form an electrode assembly3. The electrochemical cell2is arranged in spatial proximity to the magnetic flux generator1such that it is permeated by at least one of the magnetic fields generated by the plurality of magnetic field sources6. Specifically, in this example, the cell2overlies (i.e. it is parallel to and spaced from) the magnetic flux generator1.

The magnetic flux generator1ofFIG.1may be used with different types of electrochemical cell, in addition to pouch and prismatic. For example, the magnetic flux generator may be used with coin cells as well as cylindrical cells to enhance their ion transport. This is shown inFIG.3where the magnetic flux generator1is arranged in close spatial proximity to a cylindrical cell2. The cylindrical cell is positioned above the magnetic flux generator such that it is permeated by at least one of the magnetic fields generated by the plurality of magnetic field sources6. As before, the cylindrical cell2comprises an electrode assembly3enclosed within a housing5.

The plurality of magnetic field sources6may be arranged on differently shaped mechanical supports8, not just planar. For example, the mechanical support8may be curved, semi-circular, circular, or polygonal. Thus, the magnetic field sources may be arranged around a curve, arc, circle, or a polygon. Such a magnetic flux generator1is referred to as a curved magnetic flux generator and exemplified by the embodiment shown inFIG.4. In this example, the mechanical support8is octagonal and the magnetic field sources6are arranged on respective inner faces of the octagonal support to provide a central empty space. This central empty space is for reception of an electrochemical cell, as shown inFIG.4where a cylindrical electrochemical cell2is inserted. Conveniently, this can ensure that the electrochemical cell2received within the central empty space is uniformly permeated by the total changing magnetic field generated by the magnetic flux generator1.

When each magnetic field source6is an air-core electromagnet16(i.e. a coil of wire (solenoid) comprising a central air-filled space defined by the coil and not comprising a solid core), the magnetic flux generator1may be provided by stacking the plurality of air-core electromagnets16to provide a shared air core common to all air-core electromagnets. This is shown inFIG.5A. The shared air core can accommodate an electrochemical cell. For example, a cylindrical electrochemical cell2can be inserted into the shared air core as shown inFIG.5Ato obtain the arrangement shown inFIG.5B. Thus, the magnetic flux generator1at least partially surrounds the electrochemical cell2.

As discussed with reference toFIGS.2-5Babove, the magnetic flux generator1can be arranged in spatial proximity to an electrochemical cell2and externally to it. However, it is also possible that the magnetic flux generator is integrated inside an electrochemical cell. Examples of this are discussed with reference toFIGS.6A-7B.

In bothFIGS.6A and6B, the magnetic flux generator1comprises a plurality of magnetic field sources6(three of which are shown) integrated inside a flat electrochemical cell2(e.g. pouch or prismatic). In the example ofFIG.6A, the magnetic field sources6are arranged on an inner wall of the cell housing5enclosing the electrodes13and electrolyte12of the electrochemical cell2. In contrast, inFIG.6B, the magnetic field sources6are arranged between layers of the electrochemical cell2, i.e. between the electrodes13and within the electrolyte12.

Alternatively, the magnetic flux generator1may be integrated inside a non-planar electrochemical cell such as a cylindrical cell. This is shown inFIGS.7A and7B. In the variant ofFIG.7A, the magnetic flux generator1comprises a single magnetic field source6which is a permanent magnet17coupled to a mechanism (not shown) for moving the permanent magnet. The permanent magnet17is shown outside the cell, at the bottom ofFIG.7A, for reference. In the embodiment, the magnetic field source6(i.e. the permanent magnet17coupled to its mechanism) is integrated inside the cell2, on an inner wall of the cell housing5, such that the magnetic field source6longitudinally spaces the inner wall of the cell housing from the electrode assembly3. As discussed before, the choice of magnetic field source6is not particularly restricted and, in addition to a permanent magnet, the magnetic field source may be an electromagnet, or a temporary magnet.

Indeed,FIG.7Bshows an alternative arrangement where the magnetic flux generator1is provided by a plurality of air-core electromagnets16stacked to provide a shared air core as in the example ofFIGS.5A-5B. An example of a single air-core electromagnet16is shown for reference under the electrochemical cell, at the bottom ofFIG.7B. The air-core electromagnets16are each wound around and/or through layers (e.g. the electrode assembly3) of the cylindrical electrochemical cell2.

Modifications to the above embodiments are possible. The choice of magnet providing the magnetic field source(s) is not particularly limited inasmuch each magnetic field source can produce a respective magnetic field which is individually controllably variable in the three spatial dimensions. The electrochemical cell may be a battery. The battery may be a positive ion battery and the current flow path may be the direction of travel of positive ions. The battery may be a lithium-ion battery. Alternatively, the battery may be a negative ion battery and the current flow path may be the direction of travel of negative ions. The cell may be for powering an electric vehicle, a mobile phone, a laptop computer, tablet or other portable or stationary device. The electrochemical cell may be a fuel cell.

As discussed above, each magnetic field source of the present invention is configured to produce a respective magnetic field which is individually controllably variable in the three spatial dimensions. This is to allow the total changing magnetic field generated by the magnetic flux generator to be reliably varied.

An example of individually controllably varying each of four magnetic fields in the three spatial dimensions is discussed with reference toFIGS.8A and8B. The magnetic flux generator1is shown inFIG.8Aand comprises four magnetic field sources6a,6b,6c,6din a 2×2 grid arrangement on a planar mechanical support8. The schematic top view of the magnetic flux generator is shown on the right-hand side ofFIG.8A, showing a 2×2 grid with the four magnetic field sources6a,6b,6c,6d.It is possible to vary the total changing magnetic field produced by the magnetic flux generator1by individually and controllably varying each magnetic field produced by a respective magnetic field source6a,6b,6c,6d.

FIG.8Bshows how to achieve a circularly rotating total changing magnetic field in the clockwise direction (shown in the simplified grid ofFIG.8A) by sequentially controlling the four magnetic field sources. Specifically, each of the four magnetic field sources is controlled to either have a predetermined polarity (south S or north N) which can be reversed/alternated, or to be completely switched off. Generally, when the magnetic field sources are permanent magnets, they can be moved to a particular orientation (e.g. rotated in a particular direction) to control their polarity, or kept stationary to switch them off. In the example ofFIGS.8A and8B, the magnetic field sources6a,6b,6c,6dare electromagnets. Thus, inFIG.8A, each electromagnet is either switched off by not supplying any electrical power to it, or its polarity is varied between N and S by supplying electrical current having a specifically selected direction. That is, supplying current via the electrical connections9in a direction from A to B or B to A, (seeFIG.8A) results is either a north N or south S polarity on the surface of the array.

The polarity N, S of each magnetic field source6a,6b,6c,6dmay be varied in a step-like manner as shown inFIG.8Bor alternatively it may be varied gradually over time.FIGS.9A-9Eillustrate this by showing time-evolving example electrical current functions representing electrical currents supplied to different magnetic field sources.FIG.9Ashows an electrical current function evolving in a step-like manner over time. In contrast,FIGS.9B-9Eshow electrical current functions having a sine form and evolving gradually over time. In the examples ofFIGS.9C-9E, the total electrical current supplied to magnetic flux generator1is represented by a superposition of multiple electrical current functions, e.g. two sine waves out-of-phase, and/or of different amplitude, and/or of different frequency. The superposition of multiple electric current functions (each corresponding to a respective magnetic field source) may be said to generate a “magnetic field signature” of the total changing magnetic field generated by the magnetic flux generator1.

The magnetic field produced by each magnetic field source may be individually and controllably varied by a controller10comprised by the magnetic flux generator1. This is shown inFIGS.10and11. InFIG.10, the controller is electrically connected to the magnetic flux generator1and an electrochemical cell2located within at least one of the magnetic fields generated by the magnetic field sources.

In the examples ofFIGS.10and11, the electrochemical cell2is a flat cell overlying the magnetic flux generator1. The controller10is configured to monitor electrochemical overpotential of the electrochemical cell as each of the magnetic fields is individually controllably varied (e.g. as discussed with reference toFIGS.8A-9E). The controller10is further configured to select an optimal value for each of the three spatial dimensions of each magnetic field to minimize the electrochemical overpotential. Optionally, the controller may also select an optimal value for any one or any combination of the polarity, magnitude, phase, amplitude, and/or frequency of each magnetic field to minimize the electrochemical overpotential. The controller10may repeat the monitoring of electrochemical overpotential and the selection of optimal values as many times as required to minimize the electrochemical overpotential. The optimal parameters selected for each magnetic field need not be identical. Indeed, the controller may select different optimal parameter values for each magnetic field as this can help improve the homogeneity of ion transport enhancement across the electrochemical cell.

The controller10of the example shown inFIG.10is configured to monitor each electrochemical overpotential via direct overpotential measurements. The direct overpotential measurements may be performed for example using electrochemical impedance spectroscopy. Alternatively, any one or any combination of the amplitude, phase shift, and frequency of the cell's electrochemical potential or electrical current may be measured to monitor the electrochemical overpotential. The controller10can measure these via its electrical connection to the electrochemical cell2.

Alternatively, the electrochemical overpotential of the electrochemical cell2may be monitored using any one of or any combination of electric, magnetic, optical, acoustic measurements performed on the cell. These measurements can act as a proxy for determining the electrochemical overpotential. A corresponding variant arrangement is shown inFIG.11where the controller10is further communicatively and/or electrically connected to a sensor unit11comprising a plurality of sensors18. The plurality of sensors18maybe include any one or any combination of Hall sensors, Gauss sensors, optical sensors (e.g. measuring deformation and/or build-up/loss of material at selected locations on the electrochemical cell2), and/or acoustic sensors (e.g. measuring decibel response to acoustic signals transmitted to/reflected from selected locations on the electrochemical cell2).FIG.11further shows an area2′ on the electrochemical cell2which is performing differently to the rest of the cell, e.g. it is underperforming. Thus, the controller10can detect this discrepancy in performance via the overpotential measurements and set the optimal parameter values for a specific magnetic field source/a group of magnetic field sources whose magnetic field(s) permeate the underperforming region2′, to account for the local lower performance, thereby homogenising the macroscopic (overall) cell performance across its volume.

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.

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.

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.

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

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.

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%.