GB2604124A

GB2604124A - Energy Cells

Info

Publication number: GB2604124A
Application number: GB2102634.9A
Authority: GB
Inventors: Miles Anthony; Robert Hughes Stephen
Original assignee: DST Innovations Ltd
Current assignee: DST Innovations Ltd
Priority date: 2021-02-24
Filing date: 2021-02-24
Publication date: 2022-08-31
Also published as: GB202102634D0; WO2022180395A1

Abstract

An energy storage cell including a monolithic three-dimensional corrugated current collector is provided, capable of facilitating the creation of thick electrodes whilst maintaining high electronic and ionic conductivity, energy density and mechanical stability. An associated method of forming the energy storage cell is provided which improves the speed, simplicity and cost effectiveness of forming energy storage cells. The corrugated current collector is preferably formed from a unitary sheet of material and may be formed by folding, e.g. by pressing or stamping using a mould. Compartments formed by the corrugations may be provided with one or more conductive support members, such as a coil, rod or foam. Electrode material may be provided in the compartments and may coat the support members when present. The electrode material preferably comprises active material, electrolyte and a conductive additive. In further aspects, the cell comprises a current collector, a separator and electrode material for forming an anode or cathode located therebetween, wherein (a) at least one conductive support member is located in the electrode material, (b) the electrode material comprises active material, electrolyte and a conductive additive, and (c) the electrode material comprises macropore channels for containing electrolyte.

Description

Energy Cells

Field of the Invention

[1] The present invention relates to devices which can store energy and methods of manufacturing them, and particularly to energy storage devices including electrodes and methods of constructing them, for example batteries and capacitors.

Background of the Invention

[2] Energy storage devices come in a number of forms, such as batteries, capacitors, supercapacitors, ultracapacitors, and hybrid types of energy storage cell. However, current energy storage cells and their methods of manufacture suffer from a number of 10 drawbacks.

[3] One disadvantageous aspect is that a large extent of the overall mass of electrochemical energy storage devices is attributed to inactive material in the form of the packaging, current collector and separator, as opposed to active material able to deliver and store energy. For example, in conventional batteries approximately 50% of the volume is attributed to inactive material. This is problematic as many energy storage systems reported in the state of the art have energy density (watt-hours per kilogram (Wh/kg)) defined by weight of active material at electrode level, and therefore actually fall short of providing high energy components at the pack and device level when the weight and volume of inactive components considered. Hence it is the energy density at the pack and device level that is most important, for instance in the field of electric cars in which maximum energy density with minimum weight and volume is critical. As such, it is highly desirable that the proportion of inactive material in energy storage devices is reduced such that the energy density for any particular volume of energy storage device is increased. 1004] A related problem is that the more components an energy storage device includes, the more points of failure it has. This applies both to the final device, but also to the manufacturing process which therefore has more stages and hence more opportunities for error. Additionally, the increased number of manufacturing stages results in a more complex, slow and costly manufacturing process. Any improvements in the simplicity, speed and cost of production of energy storage devices are highly desirable as a large proportion of the overall cost of these devices is attributable to the limitations of their current manufacturing processes. Hence, any reduction in inactive material components in an energy storage device is highly desirable in both the final device and the manufacturing process.

[5] A number of the above problems can be addressed by the use of a thicker electrode layer in energy storage devices. In particular as the thicker each electrode layer, the fewer electrode layers are required for any particular volume of energy storage device. As each electrode layer has an associated set of inactive materials such as packaging, current collectors and separators, every electrode layer removed also removes the proportion of inactive material in the energy storage device as compared increased proportion of the energy storage device which is now occupied by the active material of the thicker electrode. Hence the thicker electrodes provide fewer components per energy storage device, which then allows for simpler, faster and cheaper manufacturing processes.

[6] However, increasing the electrode thickness in conventional energy storage cells has its own drawbacks, from the perspective of both the final device and the manufacturing process. In particular, in conventional energy storage cells, the thicker the electrode the lower the conductivity, as the rate of both ionic and electronic charge transport is decreased due to the increased distance of active material away from the current collector and separator, and hence increased resistance to charge transport. This puts a limit on how thick it is useful to make conventional electrodes, as they soon reach a thickness where the areas of active material furthest away from the current collectors and separators are not contributing to charge transport at all, and hence energy density is actually reducing the thicker the electrode becomes beyond this point.

1007] Another problem associated with making conventional electrodes thicker is that ionic movement is strongly affected by size and structure of pores in the active material, with low porosity generally leading to high tortuosity, high resistance and slow ionic transport. This effect is magnified in thicker electrodes. Electrode materials in the state of the art typically include single pore active material structures, with pore size in the micro or nano scale range. This single small pore structure can cause considerable difficulties in wetting the active material with electrolyte, as the electrolyte is often unable to penetrate the active material comprehensively, for instance with the deepest pores remaining dry and without electrolyte coverage. Active material not in contact with electrolyte is unable to transfer charge, and hence these areas are dead zones providing no energy storage capability or capacity. These arrangements therefore have inefficient energy densities.

[8] From a manufacturing perspective, thick electrodes are also difficult to make and prone to failure. For instance, it is particularly difficult to manufacture thick electrodes using conventional slurry coating procedures, which require repeated layers of electrode slurry to be formed on a current collector, gradually building up the thickness of the electrode through multiple and repeated layer applications. The electrode slurry then needs to be dried in dedicated drying stages, at least a single time but potentially a repeated number of times per layer, which are slow processes and require bulky equipment and extra space resources. The final electrode so formed then still needs to be cut into the required electrode shape in a separate step, and then formed into stacks. This requires a large number of stages, each of which increases cost and slows down the formation of the energy storage device. Even so, the final electrode formed using such procedures has low mechanical stability and is disadvantageously prone to brittleness, cracks and delamination.

[9] Additionally, thickness variations in electrodes are detrimental as they cause potential and temperature gradients, leading to faster battery degradation. Current energy cell manufacturing methods attempt to address thickness variations by including electrode coating stages which rely on tension being applied to the current collector foil for thickness precision. Consequently, these conventional methods favour the use of thicker current collector foils, thinner electrode coating and slow processing speed. This further inhibits the ability to produce thick electrodes using state of the art methods.

[10] Accordingly, there are many common and recurring issues with the manufacture and design of conventional energy storage cell devices that need to be addressed in the state of the art. It would be beneficial in the field if it were possible to create thick electrodes without compromising electronic or ionic conductivity and mechanical stability this would allow significant improvements in energy density and active material loading.

There is also a need for more cost effective, fast and simplified manufacturing processes for energy storage cells.

Statement of the Invention

[11] Aspects of the invention are defined by the accompanying claims.

1012] Embodiments of the present invention may comprise energy storage cells which include advantageously thick electrodes with high energy density, electronic conductivity and mechanical stability. In particular, in addressing the above, aspects of the present invention provide for improved electrolyte penetration and ionic conductivity in electrode layers, improved configurations of current collectors providing enhanced conductivity and mechanical stability, improved energy density through the removal of inactive components, and optimisations in thermal and current distribution.

[013] Embodiments of the present invention may also comprise improved manufacturing methods of energy storage cells, in which the energy storage cells exhibit the above advantageous properties, and the method of manufacturing them is advantageously fast, simple and cost effective as compared to state of the art methods.

[14] In particular, in addressing the above, embodiments of the present invention provide for a manufacturing method with improved stability and reliability, fewer processing steps and fewer points of potential failure, faster and more accurate electrode layer formation, and cheaper processes requiring fewer manufacturing resources.

[15] Embodiments of the present invention may overcome the problems in the art, and for instance provide for the creation of energy storage cells with advantageously thick electrodes, and provides for fast and simple manufacturing processes for producing the same.

[16] Embodiments of the present invention may provide an improved energy storage cell with respect to the state of the art, and an advantageous method of producing an energy storage cell. The energy storage cell is configured to store energy, for instance in a manner which can be used to power an electrical circuit. The energy storage cell may for instance store energy chemically, in an electric field, or both. Accordingly, the energy storage cell may for instance be a battery, capacitor, supercapacitor, ultracapacitor, or hybrid type of energy storage cell, depending on the materials used. Example materials which may be used in the energy storage cell are lithium, cobalt, sodium, and/or carbon.

[017] According to an aspect there is provided a method of forming an energy storage cell which has a monolithic corrugated current collector in a three-dimensional configuration, where the method includes forming the corrugated current collector into the three-dimensional configuration.

1018] Preferably, the three dimensional corrugated current collector is formed into its three dimensional configuration by starting from a single sheet of current collector material. This unitary planar sheet of current collector starting material may for example be folded, pressed or somehow shaped into the three dimensional corrugated configuration of the final current collector.

[19] Preferably, the method may further include inserting a conductive support, for providing structural support to the energy storage cell, into the corrugated current collector after forming the corrugated current collector into the three-dimensional configuration, such that the at least one conductive support member passes through a compartment or compartments of the corrugated current collector.

[20] Preferably, the method may further include inserting electrode material for forming a cathode or anode into a compartment of the corrugated current collector, after forming the corrugated current collector in a three-dimensional configuration, such that the shape and thickness of the at least one compartment or plurality of compartments is used to define the shape and thickness of the electrode material in the energy storage cell. Optionally, the method may further include forming the electrode material by mixing an active material, an electrolyte and a conductive additive before locating the electrode material in the compartment of the corrugated current collector, where the conductive additive may include particles fibres, needles, rods, flakes, filaments, plates or ribbons, or any combination thereof. Preferably, the method may further include forming macro pore channels in the electrode material which can be used to contain electrolyte in the cathode or anode of the energy storage cell.

[021] Preferably, the method may further include forming the corrugated current collector into a tray configuration, or a chevron configuration, or a wave configuration, wherein at least one compartment is in a tray configuration, or a chevron configuration, or a wave configuration. Alternatively, the method may further include forming the corrugated current collector in a textured surface configuration, wherein at least one compartment is formed by indentations between bumps or ridges.

1022] Preferably, the method may include forming the energy storage cell, including the corrugated three dimensional current collector, such that it have the conductive support member, the conductive additive and the macro pores as outlined above, or any combination thereof.

[023] According an aspect there is provided a method of forming an energy storage device including a plurality of the energy storage cells as outlined above.

[24] According an aspect there is provided an energy storage cell having a monolithic corrugated current collector in a three-dimensional configuration.

[25] Preferably, the energy storage cell includes a conductive support member, for providing additional conductivity and structural support to the energy storage cell, located in the corrugated current collector.

[26] Preferably, the corrugated current collector includes a compartment, and the compartment includes electrode material for forming a cathode or anode, wherein the shape and thickness of the electrode material in the energy storage cell is defined by the shape and thickness of the at least one compartment. Preferably, the electrode material comprises an active material, an electrolyte and a conductive additive, wherein the conductive additive may for example includes conductive particles, fibres, needles, rods, flakes, filaments, plates or ribbons, or any combination thereof. Preferably, the electrode material also includes macro pore channels for containing electrolyte which can be used to contain electrolyte in the cathode or anode of the energy storage cell.

1027] Preferably, the corrugated current collector may be in a tray configuration, or a chevron configuration, or a wave configuration, wherein at least one compartment is in a tray configuration, or a chevron configuration, or a wave configuration. Alternatively, the corrugated current collector may be in a textured surface configuration, wherein at least one compartment is formed by indentations between bumps or ridges.

[028] According an aspect there is provided an energy storage device having plurality of the energy storage cells as outlined above.

1029] Preferably, the energy storage cell, including the corrugated three dimensional current collector, may have the conductive support member, the conductive additive and the macro pores as outlined above, or any combination thereof.

[030] According to an aspect there is provided an energy storage cell including a current collector, a separator and electrode material to form a cathode or anode located between the current collector and the separator, where the energy storage cell further includes a conductive support member located in the electrode material to provide structural support to the energy storage cell.

[031] According to an aspect there is provided an energy storage cell including a current collector, a separator and electrode material to form a cathode or anode located between the current collector and the separator, where the energy storage cell further includes electrode material having active material, an electrolyte and a conductive additive.

[32] According to an aspect there is provided an energy storage cell including a current collector, a separator and electrode material to form a cathode or anode located between the current collector and the separator, where the electrode material includes macro pore channels which can be used to contain electrolyte in the cathode or anode of the energy storage cell.

[33] Preferred optional features are defined in the dependent claims.

[34] Various embodiments and aspects of the invention are described without limitation 1 0 below, with reference to the figures.

Brief Description of the Drawings

[35] There now follows, by way of example only, a detailed description of preferred embodiments of the present invention, with reference to the figures identified below. Figure 1 shows a cross section of an energy storage cell according to an embodiment of the present invention; Figure 2 shows section A of the energy storage cell of Figure 1; Figure 3 shows a cross section of an energy storage device including a plurality of energy storage cells according to an embodiment of the present invention; Figure 4 shows a cross section of an energy storage cell according to an embodiment of the present invention; Figure 5 shows section B of the energy storage cell of Figure 4; Figures 6 to 13 show methods of forming an energy storage cell according to embodiments of the present invention; Figures 14 and 15 show alternative shapes of three-dimensional current collectors according to embodiments of the present invention; Figure 16 shows a cross section of an energy storage cell according to an embodiment of the present invention.

Detailed Description

[36] In the following description, functionally similar parts carry the same reference numerals between figures.

[37] Referring to Figs. 1 and 2, an energy storage cell 1 of an embodiment of the present invention includes current collectors such as cathode current collector 3 and anode current collector 5. The current collectors 3, 5 may be made of any suitable conductive material. For instance, the current collectors 3, 5 may be made of metallic foils such as aluminium, copper, nickel, silver, titanium, steel or any other conductive material. The energy storage cell 1 further comprises a separator 7 which separates and compartmentalizes the cathode section 11 of the energy storage cell 1 from the anode section 13 of the energy storage cell. The separator 7 may for instance be configured to allow the passage of ions but prevent the passage of electrons, or may be any other conventional arrangement. The cathode section 11 is the side or area of the energy storage cell 1 between the cathode current collector 3 and the separator 7 and comprises an electrode material 9, the anode section 13 is the side or area of the energy storage cell 1 between the anode current collector S and the separator 7 and comprises another electrode material 9. The electrode materials 9 in the cathode section 11 and the anode section 13 may be the same or different, depending on the application. The electrode material 9 will be described in further detail below.

[38] Preferred embodiments are described below in the context of three-dimensional current collector geometries. However, many of the aspects described in the context of three-dimensional current collector geometries may also be applied to conventional two-dimensional current collector geometries, with for instance flat or planar current collectors. Purely for clarity and consistency, the preferred embodiments described below will be described in the context of three-dimensional current collector geometries, however the invention is not so limited. Example alternative embodiments of the present invention applied to two-dimensional current collector geometries are referenced when discussing the preferred embodiments, and are discussed in further detail in the subsequent alternative embodiments section.

[39] The preferred embodiments of the energy storage cells 1 of the present invention advantageously include a three-dimensional configuration of current collector(s) 3, 5. In particular, the configuration of the current collectors 3, 5 includes shapes and arrangements in which the current collectors 3, 5 are not flat or planar current collectors or electrodes such as those known in the art, but instead extend in three-dimensions within the energy storage cell 1. For instance, with reference to the flat or planar separator 7, the cathode current collector 3 and anode current collector 5 extend in directions both substantially perpendicular to and substantially parallel to the separator 7 in a configuration that is three-dimensional. In other words, the current collectors 3, 5 extend in width, depth and height within the energy storage cell 1. Hence the current collectors 3, 5 are arranged in a shape and configuration which is three-dimensional.

[40] Further, in preferred embodiments each of the current collectors 3, 5 of each energy storage cell 1 are advantageously single monolithic current collectors 3, 5. In other words each current collector 3, 5 is a single seamless current collector 3, 5, regardless of its particular three-dimensional shape or configuration. Each current collector 3, 5 may be formed from a unitary piece of starting current collector material, instead of being formed by combining a plurality of pieces of current collector material, such as by welding. For instance, each three-dimensional current collector 3, 5 may be formed from a unitary sheet of starting current collector material.

[41] As such, as will be described further below, embodiments of the present invention are particularly advantageous as the monolithic current collectors 3, 5 provide for a number of advantages. Firstly, the monolithic current collectors 3, 5 provide improved and uniform conduction through the entirety of the current collectors 3, 5, for instance by avoiding the increased electrical resistance present at junction or connection points when two conductors are combined together. In particular, monolithic current collectors 3, 5 formed from a single piece of starting material have continuous internal material lattices and structural properties, providing for improved charge carrier conduction. Secondly, energy storage cells 1 including the monolithic current collectors 3, 5 according to embodiments of the present invention provide improved structural durability, longevity and flexibility, for instance by avoiding the potential failure points found in the weakness of junctions and connection points, reducing the chance of electrode leakage, and being better able to withstand localised swelling, without failure in use. Thirdly, the formation of the monolithic current collectors 3, 5 is advantageously fast, simple and efficient, for instance avoiding the need to additionally combine pieces of current collector material. 1042] Figs. 1 and 2 show a cross-section through the energy storage cell 1, where Fig. 2 is the enlarged portion of section A of Fig. 1. As shown in Figs. 1 and 2 the three-dimensional current collectors (cathode 3 and anode 5) may be formed in a corrugated arrangement. For instance, the corrugations may be chevrons, waves, arrows, pyramids or any other suitable 3D shape as would be understood by the skilled person. Further, the corrugations may be formed by a textured configuration on the surface(s) of the current collectors 3, 5, for instance in the form of indentations, bumps and/or ridges, or any combination thereof. Regardless of the specific shape of the corrugated cathode current collector 3 and anode current collector 5, the current collectors 3, 5 may be configured such that they each respectively encase or surround the electrode material 9 between themselves and the separator 7.

[43] In the specific embodiment of Figs. 1 and 2 the cathode current collector 3 and anode current collector 5 are formed in a shape that, when viewed from left to right, is first in the proximity of the separator 7, then extends away from the separator 7 in a substantially perpendicular direction, then extends in a direction substantially parallel to the separator 7, and then extends toward the separator 7 in a substantially perpendicular direction to return to the proximity of the separator 7. This arrangement may be referred to as a tray shaped configuration. The locations at which the cathode current collector 3 and anode current collectors are in relative proximity to the separator 7 will be referred to as corrugation sites 17. Such a configuration advantageously creates a substantially enclosed area between each of the cathode current collector 3 and anode current collector 5 and the respective side of the separator 7 in which to locate the electrode material 9.

[44] Such an arrangement of a three-dimensional cathode current collector 3 and anode current collector 5 which includes electrode material 9, either by substantially encasing or surrounding it or otherwise, may be considered a single compartment 15 of the energy storage cell 1. To form an energy storage cell 1, only a single three-dimensional cathode current collector 3 and anode current collector 5 compartment arrangement may be required. However, as shown in Figs. 1 and 2, both the cathode section 11 and the anode section 13 may comprise a plurality of connected compartments 15, each separated by a respective corrugation site 17, which form the complete energy storage cell 1. Any number of compartments 15 may be provided per energy storage cell 1, which may be varied for instance depending on the intended use of the energy storage cell 1. For instance, as shown in Fig. 3, a stack of five energy storage cells 1 may be formed to create a combined energy storage device, with each energy storage cell 1 comprising six compartments 15 for each of the corrugated cathode current collector 3 and anode current collectors.

[45] For pictorial clarity, the corrugation sites 17 are shown in the Figures as including a gap separating adjacent current collectors 3, 5, however it is noted that corrugation sites 17 may be formed with substantially no separation or gap between adjacent compartments 15. Such an arrangement would be advantageously space efficient. For instance, from the cross-section perspective of Fig. 3, instead of being formed in a U-shaped arrangement the corrugation sites 17 may be formed in an I-shaped arrangement, or in an arrangement similar to a cross, pulse or heartbeat being depicted on an electrocardiogram. The pulse arrangement may be considered the same as the heartbeat arrangement but with no gap at all between the corrugations, for instance being formed by compacting together to remove any such gap. Such arrangements are particularly applicable to and advantageous in double-sided electrode configurations, in which the active material 9 both above and below the current collector 3,5 is of the same type, i.e. in the case of an cathode current collector 3 the active material 9 both above and below the cathode current collector 3 is the same active material 9 suitable for use in the cathode. In these instances current collector 3, 5 arrangements which extend both toward and away from the separator 7, such as the heartbeat, are particularly applicable to double-sided electrodes in a stack as the current collector 3, 5 therefore extends both towards a separator 7 below it, and towards a second separator] above it.

[46] The three-dimensional current collector 3, 5 arrangement may be a repeating symmetric pattern of similarly sized and shaped cathode current collector 3 and anode current collector 5 compartments 15. Alternatively, the three-dimensional current collector cathodes 3 could be of one shape or configuration and the respective three-dimensional current collector anodes 5 could be of a different shape or configuration. Alternatively, the shape or configuration of adjacent or connected compartments 15 of the cathode current collector 3 could be different, and they may be alternately different in a repeating symmetric pattern etc. Similarly, the shape or configuration of adjacent or connected compartments 15 of the anode 5 could be different, and they may be alternately different in a repeating symmetric pattern etc. Further, the shape or configuration of adjacent compartments 15 of either or both of the current collectors 3, 5 may be defined in a plurality of different directions across the energy storage cell 1. For instance, the shape or configuration of adjacent compartments 15 of either or both of the current collectors 3, 5 may have a particular pattern or configuration in one direction across the energy storage cell 1, and the same or a different pattern or configuration in a perpendicular direction across the energy storage cell 1. For instance, the compartments 15 of the energy storage cell 1 when viewed from above (such as the orientation of the views shown in Figures 11 and 12) may be substantially rectangular in an arrangement similar to an ice-tray, with corrugations of adjacent compartments 15 extending in a first direction across the energy storage cell 1 and in a second direction perpendicular to the first direction across another dimension of the energy storage cell 1. Alternatively, any combination of the above repeating or non-repeating, symmetric or non-symmetric arrangements may be employed, where the arrangements are defined in a single linear direction or a three-dimensional plurality of different directions across the energy storage cell 1. Similarly, the separators 7 can be configured in a vertical arrangement, or any other suitable directional configuration within the energy storage cell 1. Further shapes and configurations of the three-dimensional current collectors in alternative embodiments are shown in Figs. 14 and 15.

1047] In configurations in which there are a plurality of compartments 15 formed by three-dimensional cathode current collector 3 and three-dimensional anode current collector 5, each of the cathode current collector 3 and anode current collector.5 may preferably be continuous across the entire length of the energy storage cell 1. In particular, both the cathode current collector 3 and the anode current collector 5 may completely encase the electrode material 9 in each respective compartment 15 such that at the location where the cathode current collector 3 or anode current collector 5 meet the separator 7 and form a corrugation site 17 they extend continuously, for instance across the surface of the separator 7, before continuing to form the next compartment 15 by extending away from the separator 7 again. As will be described further below, configurations according to embodiments of the present invention may allow for advantageously fast and simple methods of the formation of the electrode layers 11 and 13, including in the introduction of the electrode material 9 to the shaped three-dimensional current collectors 3, 5.

1048] Advantageously, the three-dimensional configuration of the current collectors 3, 5 according to embodiments of the present invention may provide for numerous improvements over the energy storage cell configurations of the state of the art. Firstly, it allows for the electrode layers 11 and 13 to be created thicker than in prior art configurations. In particular because, as described previously, the thickness of prior art electrode layers is limited by the fact that as the electrode layer becomes thicker there becomes an increasing number of areas of the active material which are a long distance away from the current collector and separator, and which therefore limits ionic and electronic charge transport from those areas due to increased resistance. In the three-dimensional current collectors of embodiments of the present invention this problem is advantageously overcome because the three-dimensional current collectors 3 and 5 extend in both vertical and horizontal -in other words in width, depth and height -directions within the electrode layers 11 and 13, hence providing for at least the majority of locations within the electrode material 9 a shorter distance to the current collectors 3 and 5 and separator 7 for the electrons or ions to travel, hence reducing resistance and increasing conductivity. This is distinctly advantageous as it allows significantly thicker electrode layers 11 and 13 as compared to the prior art. For instance, active material in conventional supercapacitors is typically few tens (or even hundreds) of microns away from the current collector, thereby disadvantageously affecting accessibility of the active material and causing power deficiencies. The three-dimensional current collectors 3 and 5 of the present invention advantageously dramatically reduce the distance between the active material and the current collectors 3 and 5 to a few microns, ensuring effective accessibility and improving power capabilities. Further, as previously described, the monolithic nature of the current collectors 3, 5 according to embodiments of the present invention, further enhance this advantageous improvement in conductivity by providing a uniform material without junction points through which charge carriers are easily conducted.

[049] Secondly, the increased thickness of the electrode layers 13 and 15 advantageously allow that for any particular volume of energy storage cell 1, there is a smaller number of electrode layers 11 and 13 required to fill this volume as compared to the state of the art arrangements. Further still, this reduction in electrode layers 11, 13 results in a reduction in the number of current collector electrodes within the device, as each electrode layer removed also removes a required cathode current collector 3 or anode current collector 5.

Advantageously, this provides for more space within any particular energy storage cell 1 volume to be occupied by electrode material 9, and hence energy storage cells 1 according to embodiments of the present invention may have a much improved energy density compared with state of the art energy storage cells as a higher proportion of each energy storage cell 1 is able to store and generate electrical energy for any particular weight or volume. Put another way, in energy storage cells 1 according to embodiments of the present invention there is less weight and volume wasted on inactive material and components such as current collectors and separators. Hence this even further increases the energy density and volumetric efficiency of energy storage cells 1 according to embodiments of the present invention as compared with conventional energy storage cells of the same size.

[50] Thirdly, the provision of the three-dimensional current collector 3, 5 arrangement in embodiments of the present invention provides for enhanced structural rigidity and mechanical support to the energy storage cell 1 as compared to electrode arrangements in the state of the art. In particular because the reduction in the number of electrode layers, current collectors and separators provides for fewer failure points within each energy storage cell 1. Further, as previously described, the monolithic nature of the current collectors 3, 5 according to embodiments of the present invention, further enhance this advantageous enhanced structural rigidity and mechanical support by removing the potential failure points found in the weakness of junctions or connection points required by combined current collector arrangements.

[51] Fourthly, the three-dimensional current collectors 3 and 5 according to embodiments of the present invention have improved robustness because they are better able to accommodate volumetric changes, or localised swelling, in the electrode material 9 which occur during use of the energy storage cell 1. These volumetric changes may for instance cause loss of contact between active material and current collectors 3 and 5, as well as between areas of the active material itself, thereby reducing charge transport efficiencies. The three-dimensional current collectors 3 and 5 according to embodiments of the present invention advantageously allow for more flexibility in the current collectors to accommodate swelling, but also provide for a three-dimensional configuration extending through a larger area of the electrode material which results in a reduced likeliness of distance being created between the current collectors 3 and 5 and the active material at any particular location as compared to a current collector as in the state of the art. As will be described further below, the configuration of the three-dimensional current collectors 3, 5 with the conductive supports 21 of embodiments of the present invention provide even further elasticity and flexibility in the energy storage cell 1 to accommodate volumetric changes during use. Further, as previously described, the monolithic nature of the current collectors 3, 5 according to embodiments of the present invention further enhance this advantage by removing the potential failure points found in the weakness of junctions or connection points required by combined current collector arrangements.

[052] Fifthly, the three-dimensional current collectors 3, 5 according to embodiments of the present invention provide for a greater surface area of exposed current collector, on any side or surface of the energy storage cell 1, which can be used for the tab or electrical connection to components external to the energy storage cell 1, such those which it is designed to power. For instance, embodiments of the present invention allow for the entirety of the cathode current collector 3 and/or anode current collector 5 to be used as the tab, or to include a plurality of tabs, including any surface or location of the cathode current collector 3 and/or anode current collector 5. For example, the cathode current collector 3 may be formed to extend out of a first side of the energy storage cell 1, and the anode current collector 5 may be formed to extend out of a second side of the energy storage cell 1, where the two sides may be opposites, adjacent, or any suitable side. Advantageously, this provides for increased surface area tabs to be created with respect to prior art configurations, which typically create dedicated positive and negative tabs on the same side of the energy storage cell 1 which necessitates their physical separation to avoid shortcutting, and therefore reduces their size and surface area to allow for the physical separation. Advantageously, this also provides for a reduced resistance in the energy storage cell 1 and avoids the electrical bottlenecks seen in conventional single location tab designs of the state of the art. Similarly, the increased surface area of three-dimensional current collectors 3 and 5 according to embodiments of the present invention provides for increased heat dissipation during operation and thereby increases the safety of the device.

Further, the energy storage cells 1 of the present design can therefore be considered not to have a tab, as there is no need to create a separate dedicated element to form the tab as is required in prior art configurations, instead allowing for the current collectors 3, 5 themselves to be advantageously used as the tabs, for instance in the form of a wide area continuous tab. Further still, the locating of the tabs on different sides of the energy storage cell 1 advantageous avoids the additional step of having to physically separate the positive and negative tabs, for instance by cutting, as is required in prior art configurations.

For instance, in stacked energy storage cell 1 devices, all of the positive tabs may be located on one side of the energy storage device and may extend from every other energy storage cell 1 on that side, and all of the negative tabs may be located on a different side of the energy storage device and may extend from every other energy storage cell 1, offset by one with respect to the positive tabs, on that different side.

[053] In use, electronic and ionic transfer within the electrode material 9 occurs between the active material, the electrolyte and the current collectors 3, 5. Conductivity within the electrode medium 9 is significantly improved as the three-dimensional configuration of the current collectors 3 and 5 -for instance extending in width, depth and height within the electrode material 9 -advantageously provides that for any location within the electrode material 9 it is on average a shorter distance between the active material and the current collectors 3 and 5 than would be the case with a conventional current collector configuration with the same thickness. This distinct structural advantage therefore applies regardless of whether the energy storage cell 1 is in a charging or discharging cycle.

Accordingly, the electrons and ions travel along their respective paths with increased speed and energy due to lower internal resistance. This lower internal resistance aids in the reduction of disadvantageous heating and swelling of the energy storage cell 1 in use, however where swelling does occur the three-dimensional current collectors are better able to accommodate these changes as they have more degrees of freedom in which to move and flex than conventional two-dimensional current collectors. As mentioned previously, lower resistance is also advantageously achieved at the location(s) where the energy storage cell 1 is connected to external circuitry, as the three-dimensional current collectors 3 and 5 provide for an increased exposed or accessible surface area which may be used as the tab, hence again further reducing the distance of conductive transfer and the resistance within the energy storage cell 1.

1054] According to another embodiment of the present invention, and advantageous method of forming the energy storage cell 1 with the three-dimensional cathode current collector 3 or anode current collector 5 will be described. As will be described further below, the advantageous removal of electrode layers from the energy storage cell 1 of embodiments of the present invention through the provision of thicker electrodes layers 11 and 13 also advantageously allows for a simpler, cheaper and faster method of construction.

[55] The electrode material 9 within each compartment 15 may be any conventional electrode material 9. In particular, conventional electrode materials 9 include an active material, an electrolyte and a binder. In for instance capacitor arrangements the active material provides the sources of ions, the electrolyte allows the transport of ions, and the binder helps adhere these different materials together. The active material may include lithium, cobalt, sodium, and/or carbon, as well as other commonly known materials used in the construction of energy storage devices that are known in the art. The electrolyte may be water-based, organic, an ionic liquid or any other electrolyte known in the art.

[56] Alternatively or additionally, the electrode material 9 in embodiments of the invention will be described further below. In particular the electrode material 9 may be pre-mixed such that it additionally includes a conductive additive comprising conductive material 19. For instance, the electrode material 9 may be formed such that it advantageously includes a sufficient number of randomly scattered conductive additive material 19 in the form of particles, fibres, needles, rods, flakes, filaments, plates, ribbons or any other shape known in the art are added to the electrode material 9. The size of the conductive additive material 19 is not limited and they may comprise metal, non-metal, polymer or any other conducting material. As a non-limiting example, the electrode material 9 shown in the Figs. 1 to 2 includes conductive additive material 19 in the form of conductive fibres. Preferably, a layer of electrode material 9 without conductive additive material 19 is located between the separator 7 and the electrode material 9, to advantageously avoid the conductive additive material 19 piercing or bridging the separator 7 and shortcutting the system.

[57] Advantageously, the conductive additive material 19 simultaneously enhance both electronic conductivity and mechanical stability of the compartment 15 and energy storage cell 1. In particular, the conductive additive material 19 increase electronic conductivity by providing additional electric contact points and additional electron charge transport routes within the electrode material 9, such that for instance electrons are able to travel a reduced distance to reach the active material. Further advantageously, the pre-mixing of the electrode material 9 allows for the use of less binder than in conventional arrangements, as the pre-mixing of the electrolyte with the active material forms a sticky adhesive paste therefore avoiding the need to introduce additional binder in the mix to adhere the electrode material 9 to the current collectors 3, 5 as would be required in conventional applications. This also advantageously allows a higher proportion of active material to be included in the electrode material 9, hence increasing energy density further.

[58] Alternatively, in embodiments in which the electrode material 9 is not pre-mixed to include the electrolyte, the electrode material 9 including active material would be added, for instance as a conventional slurry, and then dried before electrolyte may be added in a subsequent wetting stage.

[59] In use, the conductive additive material 19 provide deeper and more comprehensive conductive penetration of the active material, as on average any location within the electrode layer 9 is likely to be closer to conductive material in the form of the conductive additive material 19 which allows a low resistance travel path for electronic transfer. Hence the electrons experiencing the electric fields within the energy storage cell 1 have lower resistance and higher conductivity in the form of more and faster travel paths, as compared to state of the art arrangements. In this way, it may be considered that the conductive additive 19 in effect becomes an advantageous extension of the current collectors 3,5 into the electrode material 9.

[60] Additionally, the advantageous effect of the conductive material 19 may be further enhanced by applying a pre-coating stage in which the conductive additive 19 itself is coated with a thin layer of highly conductive material, thereby further increase in electrical conductivity of the conductive additive 19.

[61] As will be describe further below, this arrangement of electrode material 9 with conductive additive 19 may also be advantageously included within energy storage devices with conventional two-dimensional current collector arrangements.

[62] Alternatively or additionally, the electrode layer 11, 13 and/or electrode material 9 may comprise conductive supports 21. Advantageously, the conductive supports 21 according to embodiments of the present invention simultaneously provide additional structural support and enhanced electrical conductivity to the energy storage cell 1 or energy storage device. In particular, the conductive supports 21 increase electronic conductivity by providing additional electric contact points and additional electron charge transport routes within the electrode material 9, such that charge carriers are able to travel faster and with reduced distance to reach the active material and current collectors 3 and 5. For instance, the charge carriers only have to reach the nearest conductive support 21 to find a low resistance and short distance route between the active material and current collector 3, 5. In this way, it may be considered that the conductive supports 21 in effect become an advantageous extension of the current collectors 3, 5 into the electrode material 9.

[063] Further, the conductive supports 21 are configured to be sufficiently dimensioned and of an appropriate material to provide physical structural support and mechanical stability to the energy storage cell 1 or energy storage device. For instance, the conductive supports 21 may comprise metals, non-metals, polymers or any other conducting material or a combination thereof. The conductive supports 21 may be arranged as, for instance, a pre-formed mesh, grid, scaffold or gouge configuration. Further, the conductive supports 21 may take any suitable shape, size or number within the electrode material 9 such that the conductive supports 21 advantageously provide structural support and additional functioning electronic conductivity.

[064] The conductive supports 21 are located within the compartments 15 and the electrode material 9 therein. Preferably, the conductive supports 21 extend substantially across the entire width, depth and/or height of each of the compartments 15, or any combination thereof, to advantageously provide considerable structural support and enhanced conductivity throughout the compartments 15 and energy storage cell 1 as a whole. Further, the conductive supports 21 may be positioned to extend either parallel to or perpendicular to the extension of the compartments 15 of the corrugations of the energy storage cell 1.

1065] In a preferred example, for instance as shown in Figs. 1 and 2, the conductive supports 21 extend perpendicular to the direction of extension of the compartments 15 of the corrugations of the energy storage cell 1 such that they extend across the width of the compartment 15. Additionally, a conductive support 21 may be configured such that it extends in a continuous manner between two or more adjacent compartments 15. For instance, a single conductive support 21 may extend across all of the adjacent compartments 15 of the cathode current collector 3 or anode current collector 5 across the entire width of the energy storage cell 1. Such a configuration advantageously provides even further enhanced structural support across the entire energy storage cell 1 or energy storage device. In particular, this may be achieved using a conductive support 21 in the form of a coil which may intertwine or interlock with the cathode current collector 3 or anode current collector 5 as it forms the corrugation site 17, and may thereby cross the boundary between two adjacent compartments 15. As shown in Figs. 1 and 2, such a configuration of the conductive support 21 appears as a zig-zag or 'w' shaped arrangement when viewed in cross section through the energy storage cell 1, hence extending across the width, depth and height of the compartment 15.

[66] Alternatively or additionally, the conductive supports 21 may take the form of rods, straight or otherwise. Alternatively or additionally, the conductive supports 21 may take the form of conductive foam, which may for instance be added in a direction parallel to the direction of extension of the compartments 15 of the corrugations of the energy storage cell 1 such that they extend along and in line with the length of the compartments 15, so as to provide even further enhanced electron transport conductivity.

[67] The addition of the conductive supports 21 further enhances the advantageous ability of the energy storage cell 1 to accommodate volumetric and localised swelling of the electrode material 9 that is common in use, for instance over long charge and discharge cycles. In particular, the additional mechanical stability and structural support provided by the conductive supports 21 allows for increased flexibility and elasticity in the energy storage cell 1 which will accommodate any such volumetric changes in use. This can be especially useful for anodes in the field of batteries. This advantage may be particularly evident with the coil embodiment, but will also be significantly exhibited by other shapes and configurations.

[68] In use, the conductive supports 21 simultaneously structurally support the energy storage cell 1, and provide deeper and more comprehensive conductive penetration of the active material, as on average any location within the electrode layer 9 is likely to be closer to conductive material in the form of the conductive support 21 which allows a low resistance travel path electronic transfer. Hence the electrons experiencing the electric fields within the energy storage cell 1 have lower resistance and higher conductivity in the form of more and faster travel paths.

[69] As will be describe further below, this arrangement of electrode material 9 with conductive additive 19 and/or conductive supports 21 may also be advantageously included within energy storage devices with conventional two-dimensional current collector arrangements.

[70] Both the conductive additive 19 and conductive supports 21 individually advantageously introduce additional electrical contact points, more charge carrier transport routes, and enhanced electrical conductivity within the electrode material 9 of the energy storage cells 1. The considerably enhanced conductivity provided by the conductive additive 19 and conductive supports 21, whether considered alone or together, allows even further significant increases in the thickness of the electrode layers 11 and 13 to be achieved, and substantially removes the limitation to electrode thickness in the art in which beyond a certain thickness the ionic and electronic conductivity between distant areas of the active material and the current collectors becomes too low. Further, both the conductive additive 19 and conductive supports 21 as advantageously provide increased mechanical stability to the energy storage cell 1 or energy storage device. Hence, as such the combination of the conductive additive 19 and the conductive supports 21 in a single energy storage cell 1 synergistically provides a dramatic increase in the conductivity of the energy storage cell 1, allowing for substantially increased electrode thickness as compared to state of the art implementations, and hence providing considerably higher energy density in the final electrode storage cell 1 or device.

[71] As described in the background section, electrode materials in the art typically have active materials which include a single micro or nano scale pore structure, which are intended to allow the electrolyte to penetrate into the active material. Embodiments of the present invention may have an enhanced conductivity electrode material 9 by additionally including a second pore channel structure at the macro scale, the dimensions of which would be larger than the conventional nano and micro scale pores known in the art. In particular, macro scale pores or channels 23 may be provided within the electrode material 9 in the direction extending substantially between the cathode current collector 3 or anode current collector 5 and the separator 7, for instance vertically between the two.

In use, the macro pore channel 23 structure provided in the active material of the electrode material 9 will be filled with electrolyte. The size and extent of the macro scale pores or channels 23 of the second pore channel structure is governed by the porosity of the existing single micro or nano scale pore structure of the active material, with for instance the recommended volume fraction of the second pore channel structure being equal to or lower than the porosity of the existing single micro or nano scale pore structure of the active material. Accordingly, the size and distance between macro scale pores or channels 23 of the second pore channel structure may be determined based on the original porosity of the active material. For instance, the size of the pores or channels 23 of the second pore channel structure may be between a few microns to hundreds of microns.

[72] A specific embodiment is shown in Figs. 4 and 5, wherein the electrode material 9 has macro pores 23 formed within the compartments 15. These macro pores 23 may be provided in combination with the conductive additive 19 and conductive support 21 arrangements as described previously. However, the number of macro pores 23 added to or included in the electrode material 9 may be large or small. Further, the specific embodiment of Figs. 4 and 5 shows the macro pore channel 23 structure as being straight line bore holes in the substantially vertical direction, as for instance may be formed by a cylindrical rod. However, other shapes, configurations and orientations may be used in embodiments of the present invention. In particular, the macro pores 23 can be formed in any direction, shape, length or configuration. Further, the macro pores 23 can be formed in any shape, such as for instance a cone shape, which as will be described below further improve the wettability of the pores and penetration of the electrolyte, for instance by the capillary reaction effect.

[73] Advantageously, the macro pores 23 may provide one or more distinct advantages, each of which considerably improves the conductivity of the energy storage cells 1, in particular by improving ionic conductivity. Firstly, relative to the conventional micro or nano scale pore arrangement of active material as is known in the art, the active material of the electrode material 9 may provide an advantageously improved surface area of active material in contact with electrolyte, whilst also sacrificing only a small amount of active material in the provision of the macro pore channel 23 structure.

[74] Secondly, the electrolyte penetration into the active material may be considerably improved, thereby allowing a faster, more efficient and less resistant transfer of ions to and from the active material and the electrolyte. In particular, in conventional micro or nano scale pore structures, it is difficult to ensure that the electrolyte added to the micro or nano scale pores will be effective in penetrating deep into the active material, with for instance the deepest or furthest parts of the active material from the current collectors being 'dry' and therefore of significantly reduced or no ion transfer capability.

[75] Thirdly, the macro pores 23 may act in the manner of an ionic highway, providing a fast, low resistance and short distance travel path between the separator 7, cathode current collector 3 and anode current collector 5 and the active material. In particular, relative to conventional micro or nano pore structures, the route from the deepest or furthest part of the active material to the separator 7 is considerably shorter and less tortuous.

[076] Fourthly, when the energy storage cell 1 is in use, the macro pore channel 23 structure may significantly reduce the likelihood and occurrence of electrolyte drainage, electrolyte drying and ionic conductivity reduction, in particular because the macro pore channel 23 structures additionally function as electrolyte reservoirs. This may be particular advantageous during long cycles of use of the energy storage cell 1, and may significantly increase the functioning lifetime of the energy storage cell 1 in embodiments of the present invention as compared to the state of the art. This advantage is of particular importance in the application of embodiments of the present invention to supercapacitors in which energy storage is achieved using the dual-layer effect, and/or Faradic reactions, in the pores of the active material at the interface between the active material and the electrolyte, and which suffer distinctly from the problem of insufficient electrolyte penetration into the pores of the active material. The macro pores 23 may advantageously overcome these problems through the provision of electrolyte reservoirs which serve to improve the wettability of the pores and penetration of the electrolyte, and hence create greater surface area contact between the active material and the electrolyte and therefore provide a higher energy storage capacity to the supercapacitor. In summary, amongst other advantages, the macro pores 23 of embodiments of the prevent invention may allow a larger portion of active pore sites to be accessed by the electrolyte, and hence significantly improve energy and power density of energy storage cells, hence thereby providing a more volumetrically efficient energy storage cell 1 capable of the same power output and energy storage as considerably larger state of the art energy storage cells.

[077] In use, when charge transfer is occurring at the interface between the micro and nano scale pores within the active material, the charge needs only to reach the macro pore channel 23 structure to find a low resistance and short path distance to and from the separator 7. Hence, by analogy the macro pore channel 23 structure supplements the original micro and nano scale pore structure in the manner of a motorway as compared to smaller slower roads leading to the motorway. Further, if and when electrolyte drying begins to occur at a pore site in the active material, the capillary reaction effect will draw electrolyte from the macro pores 23 which are therefore acting as electrolyte reservoirs. This is particularly advantageous for during long use cycles. Hence the lifetime of the energy storage cell 1 is improved.

[78] An advantageous method of forming the macro scale pores will be described further below. The macro pore channel 23 structure is advantageously fast and simple to form in the electrode material 9, or to apply retrospectively to a formed electrode material 9.

[79] Once a desired shape or configuration of the three-dimensional current collectors 3 and 5 has been chosen, including the number of compartments 15, the current collectors 3 and 5 can be formed into the three-dimensional configuration. For instance, a shape forming element such as a current collector mould can be created of the required shape. For instance, a pre-formed current collector mould can be created of the desired shape into which the initial unshaped current collector material can be pressed to form the desired shape three-dimensional current collectors 3 and 5. For instance, a flat unshaped piece of current collector material may be introduced to the current collector mould, which may either be left unheated, pre-heated or heated within the current collector mould. The unshaped current collector material may then be formed in the mould to create the desired three-dimensional current collector 3, 5 shape and configuration in a manner that would be understood by the skilled person.

[080] Alternatively, the three-dimensional current collectors 3 and 5 could be formed into desired shapes and configurations through heating, extrusion, deposition such as vapour deposition or 3D printing, or any other method. For instance, the current collectors 3, 5 may be formed folded into a particular shape and configuration starting from a flat unshaped piece of current collector 3, 5 material. Alternatively, the current collectors 3, 5 may be stamped or pressed into a particular shape and configuration starting from a flat unshaped piece of current collector 3, 5 material. As previously described, according to embodiments of the present invention, the current collectors 3, 5 are monolithic and may be formed, for instance, from a single unitary sheet of starting current collector material, using any of the above described processes and methods. Each of these methods could also be combined with the use of the shape forming element, such as the current collector mould described above.

[81] Advantageously, such a current collector mould not only acts as a forming tool for the three-dimensional current collectors 3 and 5, but may optionally also be used to provide support to the three-dimensional current collectors 3 and 5 during latter stages of the method as will be outlined below if the current collectors 3, 5 are left in the current collector mould during the stages. In particular, the mould may advantageously act as a base for the assembly of the energy storage cell 1, for instance during addition of the electrode material 9 or the conductive supports 21. This further provides an advantageously fast and simplified method as there is no need for the three-dimensional current collectors to be removed from the current collector mould and located on a different surface or within a different support. The use of a pre-formed current collector mould advantageously also allows for ease of manufacture and flexibility of design.

[82] Further, the monolithic current collectors 3, 5 according to embodiments of the present invention contribute to the speed, efficiency and simplicity of the method of formation, regardless of the specific shape or configuration of the three-dimensional current collectors 3, 5 chosen and regardless of the chosen method of formation of the three-dimensional configuration. In particular, starting from a single unitary piece of current collector material removes the need to include an additional stage of combining current collector materials to form a final current collector, regardless of where this stage comes in the process of forming the energy storage cell 1, such as before or after formation into the three-dimensional configuration. Accordingly, in addition to the advantageous effects of the monolithic current collectors 3, 5 in the final energy storage cell 1 or energy storage device, the monolithic current collectors 3, 5 also provide for an improved method of formation of the energy storage cell 1.

[83] Once the three-dimensional current collectors 3, 5 are formed they may be removed from the mould, or left therein as previously described. As a result of the formation step, the three-dimensional current collectors 3 and 5, as previously described in for instance the specific embodiments of Figs 1 to 5, are quickly and easily formed. For instance, as shown in Fig. 6 the three-dimensional corrugated tray shaped current collectors 3 and 5 as shown in Figs. 1 to 5 may be created, including the creation of the compartments 15 and the corrugation sites 17.

[84] In embodiments of the present invention in which the conductive supports 21 are to be included in the energy storage cell 1, this may optionally be the next stage of formation. In particular, regardless of the shape of conductive support 21 to be added, they may be added into the empty but shaped three-dimensional current collectors 3 or 5. As mentioned previously, for advantageous additional support during the formation process the three-dimensional current collectors 3 and 5 may remain within the current collector mould for this and subsequent stages.

[85] The conductive supports 21 may next be located within the compartments 15. Preferably, the conductive supports 21 extend substantially across the width, depth and/or height of each of the compartments 15, or any combination thereof, to advantageously provide considerable structural support and enhanced conductivity throughout the compartments 15 and energy storage cell 1 as a whole. Further, the conductive supports may be positioned to extend either parallel to or perpendicular to the extension of the compartments 15 of the corrugations of the energy storage cell 1. As described above, the conductive supports 21 may extend perpendicular to the extension of the compartments 15 of the corrugations of the energy storage cell 1 such that they extend across the compartment 15. Additionally, a conductive support 21 may be configured such that it extends in a continuous manner between two or more adjacent compartments 15.

[86] The conductive supports 21 may be located within the compartments 15 using pick and place machinery, and may for instance include steps to adhere the conductive supports 21 to the compartments 15. Alternatively, the conductive supports 21 may be held in position within the compartments 15 until the process is completed. Regardless, the introduction of the conductive supports 21 into the three-dimensional current collectors 3, 5 is advantageously a simple and/or single manufacturing step.

[87] In an example as shown in Fig. 7, conductive support 21 coils are added to the three-dimensional current collectors 3 and 5. For instance, these conductive support 21 coils may be added to the three-dimensional current collectors 3 and 5 such that they are perpendicular to the direction of extension of the compartments 15 of the corrugations of the energy storage cell 1. As described previously, the conductive support 21 coils may intertwine or interlock with the cathode current collector 3 or anode current collectors as it forms the corrugation site 17, and may thereby cross the boundary between two adjacent cathode current collector 3 or anode current collector 5 compartments 15. This advantageously provides additional mechanical and structural support across the entire energy storage cell 1.

[88] In an alternative as shown in Fig. 8, conductive support 21 rods are added to the three-dimensional current collectors 3 and 5. For instance, these conductive support 21 rods may be added to the three-dimensional current collectors 3 and 5 such that they are perpendicular to the direction of extension of the compartments 15 of the corrugations of the energy storage cell 1. The conductive support 21 rods may penetrate through the corrugation site 17 between compartments 15, for instance requiring drilling through areas of the current collectors 3, 5, and may thereby cross the boundary between two adjacent cathode current collector 3 or anode current collector 5 compartments 15. This advantageously provides additional mechanical and structural support across the entire energy storage cell 1.

[89] Alternatively or additionally, the conductive supports 21 can be arranged in any manner as previously described in the present disclosure.

[90] The electrode material 9, in accordance with any previous description thereof in the present disclosure, may then be added to the combined current collector 3, 5 and conductive support 21 arrangement. As previously described, this arrangement may still be located in the shape forming element, for instance mould, for additional support.

[91] In embodiments of the present invention, a conventional electrode material 9 may be used. Alternatively, the electrode material 9 may be formed by pre-mixing of the active material and the electrolyte to form a paste. Advantageously, the pre-mixing of the active material with the electrolyte in this manner provides good penetration of the electrolyte into and within the active material, thereby increasing conductivity as compared with alternate conventional methods of adding electrolyte to active material such as pouring liquid electrolyte into the solid active material. Alternatively, in embodiments in which the electrode material 9 is not pre-mixed to include the electrolyte, the electrode material 9 including active material would be added, for instance as a conventional slurry, and then dried before electrolyte may be added in a subsequent wetting stage.

[92] As previously described, an amount of advantageous conductive additive 19 may also be added to the active material and the electrolyte in forming the electrode material 9 paste. In particular, a sufficient amount of randomly scattered conductive additive 19 material may be added to the electrode material 9, where the conductive additive 19 may take the form of particles, fibres, needles, rods, flakes, filaments, plates, ribbons or any other shape known in the art. The size and material of these conductive additives 19 may be as previously described. An appropriate amount of conductive additive 19 should be added such that conductivity in the electrode material 9 is increased without adding so much that the amount of active material is effectively diluted and energy density therefore decreases.

[093] Advantageously, the pre-mixing of the conductive additive 19 into the electrode material 9 is both simple and highly effective as it provides good penetration of the conductive additive within the electrode material 9. Further, a pre-mixed electrode material 9 is advantageously fast and simple to apply to the other components.

[094] The electrode material 9 so formed may then be deposited on or compressed into the compartments 15 of the energy storage cell 1 in an advantageously simple step. In particular, the electrode material 9 may therefore be applied such that it substantially fills or overfills the compartments 15 of the current collectors 3, 5 and also surrounds the carefully positioned conductive supports 21. The electrode material 9 may also be applied in any appropriate way. Advantageously, the three-dimensional configuration of the current collectors 3, 5 helps contain the electrode material 9 such that less binder is required as compared with conventional applications. In cases in which a binder is included in the pre-mixed electrode material 9, a drying stage may need to be performed before or after the electrode material 9 is applied.

1095] Advantageously, the application of the electrode material 9 as a pre-mixed paste to the arrangement of the current collector 3, 5 compartments 15 and conductive supports 21 provides significantly improved even application as compared to conventional methods of electrode material application. In particular, the deposition under gravity and/or compression under additional force causes the electrode material 9 to coat the current collectors 3, 5 and conductive supports 21 such that their entire surface area is in contact with the electrode material 9. This provides significantly enhanced conductivity within the energy storage cell 1, as well as thereby allowing the formation of considerably thicker electrodes 11, 13 as compared to the state of the art. Such advantages may be particularly beneficial for supercapacitor applications.

1096] Further, as described in the background section, conventional slurry coating techniques for forming electrodes require multiple repeated stages of application, including layering, drying, cutting and forming into stacks etc. Advantageously, there may be a significant reduction in the number of steps required to form the desired energy storage cell 1, and hence a significant improvement in speed of formation. In particular, in the first instance the electrode material 9 can be applied in a single step, as described above, to the current collectors 3, 5. Further, this single application step simultaneously also forms the electrode material 9 into the desired final electrode shape as it is being inserted directly into the shaped three-dimensional current collector 3, 5, which in embodiments of the present invention may for instance entirely encase the electrode material 9. Hence a dramatic reduction in the number of processing steps is achieved by allowing for the combination of the electrode formation and cutting stages of the state of the art into a single step.

[097] Further, in the conventional slurry coating technique for electrode formation as known in the art, the repeated application stages and the requirement for drying lead to a significantly weaker electrode, disadvantageously having less mechanical stability leading to brittleness, cracks and delamination. This also puts a limit on the thickness of the electrodes that can be formed. As described above, various embodiments of the energy storage cell 1 of the present invention allow for the ability to provide thicker electrode layers 11, 13. The advantageous reduction of the electrode material 9 application into a single stage and removal of the requirement to apply the electrode material in multiple layering and drying stages also significantly improves the structural integrity of the electrode material 9 as a whole, as it forms and sets as a single entity with a far lower propensity to crack and substantially eliminates the problem of delamination. This advantageously allows significantly thicker electrode material 9 layers 11, 13 to be formed as compared to the state of the art. For instance, to create a thicker electrode layer 11, 13, a deeper three-dimensional cathode current collector 3 or anode current collector 5 may be used in which to introduce electrode material 9.

[098] The ability to form thicker electrodes as provided by embodiments of the present invention also allows for fewer energy storage cell 1 layers in any given size of energy storage device as compared with the state of the art. In particular, as more of the energy storage cell 1 or device can be dedicated to active material in the electrode material 9, thicker layers of electrode material 9 can be formed, and hence fewer energy storage cells 1 are needed for any particular size and hence fewer current collectors 3, 5 and separators 7 as required for each energy storage cell 1 will be included within the final energy storage device. Additionally, this advantage also allows for an improved speed of manufacture as fewer processing steps will be required to form an energy storage cell 1 of any given size, as any given size of energy storage device according to embodiments of the present invention will include fewer components than conventional energy storage devices of the same size. Further still, this reduction in the number of components that need to be located and assembled provides for a method of improved reliability, as there are fewer potential failure points in the locating and assembling of the energy storage device as compared to the more complex and delicate arrangements of the state of the art.

[099] In the above preferred arrangement, the electrode material 9 is added after the conductive supports 21. Alternatively, the electrode material 9 may be added before the conductive supports 21, in which case the conductive supports 21 must then be introduced to or forced through the electrode material 9 already within the three-dimensional current collectors 3, 5.

[0100] As a result of the above method, the electrode layers 11, 13 as shown in Figs. 9 and 10 may be formed. In particular, Fig. 9 shows the configuration including the conductive support 21 coil, and Fig. 10 shows the configuration including the conductive support 21 rod. Figs. 11 and 12 show top-down views of configurations similar to Figs. 9 and 10 respectively, except including more compartments 15.

[0101] In another embodiment of the method, macro pores 23, as previously described in the present disclosure, may then be quickly and easily added to the combined cathode current collector 3 or anode current collector 5, electrode material 9, and conductive support 21 arrangement. Preferably, this arrangement is still located within the current shape forming element, for instance collector mould, for forming the three-dimensional current collector 3, 5 configuration, and hence is advantageously supported by the shape forming element, such as the current collector mould. Alternatively, this arrangement could be located within a support element suitable for holding, supporting, and maintaining the shape of the arrangement, such as for instance a tray or rack, and hence is advantageously supported by the support element.

[0102] The macro pores 23 may be formed in the electrode material 9 by pressing a pore mould of the desired shape and configuration into the exposed surface of the electrode material 9. For instance, this second mould may be formed of a series of cylindrical rods which when pressed into the surface of the electrode material 9 form the required macro pore 23 channels in the respective locations of the electrode material 9. The macro pores 23 can be formed in any direction, shape, length or configuration, and as determined by the configuration of the pore mould. For instance, the macro pores 23 may extend substantially through an entire dimensional direction of the electrode material 9, such as through the height of the electrode material 9 in a direction perpendicular to the separator 7 and between the cathode current collector 3 or anode current collector 5 and the separator 7. Once the macro pores 23 are formed, the pore mould is then removed from the electrode material 9 leaving the created macro pore channel 23 structure present in the electrode material 9. Either next or at a later stage, these macro pores 23 are may be filled with electrolyte, in the process conventionally known as 'wetting' of the electrode material 9.

[0103] The pore mould for forming the macro pore channel 23 structure may be heated, or unheated, or may take any other suitable form which allows for formation of the macro pores 23 in the electrode material 9.

[0104] Advantageously, as previously described, the macro pore channel 23 structure provides significantly improved electrolyte wetting of the electrode material 9 during the formation stage. In particular, the macro pores 23 penetrating within the electrode material 9, and in some cases substantially through the electrode material 9, provide reservoirs of electrolyte which serve to facilitate more effective penetration of the electrolyte into the active material by capillary action. In particular, the capillary action of the electrolyte from the macro pores 23 serves to penetrate deeper into the conventional nano and micro scale pores of the active material, in a more even and substantial manner than would be achieved by relying on capillary action through only the conventional nano or micro scale pores.

[0105] Alternatively, the macro pores 23 could be formed in the electrode material 9 before it is inserted into the three-dimensional current collectors 3, 5. For instance, the macro pore channel 23 structure could be formed in the electrode material 9 by distributing the active material throughout a pre-formed structure dimensioned and located to form the macro pores 23, wherein the pre-formed structure is then subsequently removed using a chemical process or any other removal technique known in the art. Alternatively, the pre-formed structure may be located in the three-dimensional current collectors 3, 5, either before or after any conductive supports 21 have been added, and the electrode material 9 may be distributed into the three-dimensional current collectors 3, 5 and around the pre-formed structure which is then subsequently removed by chemical, physical or other known processes.

[0106] As a result of the above methods, an electrode layer 11, 13 as shown in Fig. 13 may be formed, which shows the specific embodiment of the corrugated current collector 3, 5 including the conductive support 21 coils and macro pore channel 23 structure.

[0107] Accordingly, the above methods create a single electrode layer 11, 13, with the method being equally applicable to the creation of both the cathode current collector 3 and the anode current collector 5. A separator 7 may then be located as appropriate on the electrode layer 11, 13, either before or after removal of the electrode layer 11, 13 from the support element or shape forming element for forming the three-dimensional current collector 3, 5. Preferably, in embodiments in which the electrode material 9 includes conductive additive material 19, as previously described a layer of electrode material 9 without conductive additive material 19 is also applied to the arrangement before the separator 7 is located on the electrode layer 11, 13. Finally, two electrode layers 11, 13 as formed by the above processes may then be combined such that they are formed into a single energy storage cell 1 as depicted in for instance Figs. 1 and 4. The manner of connection and integration of these two electrode layers 11, 13 to form the final energy storage cell 1 would be understood by the skilled person and is not described further here. A plurality of such energy storage cells 1 may then be combined to form an energy storage device of multiple layers, for instance as depicted in Fig. 3.

[0108] The processes described above advantageously provide a fast, simple, and inexpensive method for forming an energy storage cell 1 in accordance with embodiments of the present invention. Such an advantageous method is particularly important in the field of energy storage cells 1 and devices in which a high proportion of overall costs is attributed to the manufacturing process. The above processes are particularly advantageous when it comes to the formation of thick electrodes, which are difficult to achieve using the conventional slurry coating methods. The advantageous simplification of the process for forming energy storage cells 1 whilst simultaneously allowing for thicker electrode layers as provided for by embodiments of the present invention allows for cheaper manufacturing equipment and faster production as compared to state of the art configurations. Further, as previously outlined, the final energy storage cell 1 or device so formed is capable of including thicker electrode layers 11, 13, enhanced conductivity and a higher energy density than state of the art energy storage cells 1 or devices.

[0109] Embodiments of the present invention as depicted in Figs. 1 to 13 have been shown with the corrugated current collectors 3, 5 in a tray shaped configuration. As previously described, the three-dimensional current collectors 3, 5 may take a number of different shapes or configurations. For instance, the corrugations may be chevrons, waves, arrows, pyramids or any other suitable 3D shape. By way of example Fig. 14 shows a chevron shaped current collector 3, 5 and Fig. 15 shows a wave shaped current collector 3, 5, each depicted with the example conductive support 21 rod, although any conductive support 21 configuration may be used. In particular, the current collectors 3, 5 shown in Figs. 14 and may be used in double-sided electrode configurations, in which the active material 9 both above and below the current collector 3, 5 is of the same type, i.e. in the case of an cathode current collector 3 the active material 9 both above and below the cathode current collector 3 is the same active material 9 suitable for use in the cathode. As previously described, different shaped current collectors 3, 5 may be formed through the use of different shape forming elements, such as pre-formed moulds to shape the current collectors 3,5 in any desirable shape.

[0110] The methods of forming an energy storage cell 1 as described above, for instance with reference to Figs. 6 to 13 and the accompanying description, are equally applicable to double-sided electrode configurations as shown in Figs. 14 and 15, and in particular may be applied sequentially to both sides of the cathode current collector 3 or anode current collector 5. For instance, the current collector 3, 5 may initially have the previously described methods applied to a first side, and then the arrangement may be turned over and the processes may be repeated from the other side.

Alternative Embodiments [0111] The embodiments described above are illustrative of, rather than limiting to, the present invention. Alternative embodiments apparent on reading the above description may nevertheless fall within the scope of the invention.

[0112] For instance, the above preferred embodiments have been described in the context of current collectors of three-dimensional geometries. A number of the above described aspects are also applicable to and advantageous in two-dimensional current collector geometries. These will be described further below.

[0113] As previously described, an energy storage cell 29 according to the present invention includes current collectors such as a cathode current collector 25 and anode current collector 27, a separator 7 which separates and compartmentalizes the cathode section of the energy storage cell 1 from the anode section of the energy storage cell 29. The cathode section is the side or area of the energy storage cell 29 between the cathode current collector 25 and the separator 7 and comprises an electrode material 9, the anode section is the side or area of the energy storage cell 29 between the anode current collector 27 and the separator 7 and comprises another electrode material 9. The electrode material 9 includes the conventional components of an active material, an electrolyte and a binder.

[0114] In alternative embodiments the energy storage cells 29 include a conventional two-dimensional configuration of current collectors 25, 27. In particular, the configuration of the current collectors 25, 27includes shapes and arrangements in which the current collectors 25, 27are for instance substantially flat or planar current collectors 25, 27 or electrodes, such as those known in the art. For instance, the current collectors 25, 27 may be arranged substantially parallel to the separator 7, in a sandwich arrangement, or may be arranged in any other conventional arrangement. The skilled person will be aware of the construction and configuration of such two-dimensional current collectors in conventional energy storage cells, and they will not be described in further detail here. [0115] In particular, the advantageous configurations of the alternative embodiments focus primarily on the addition of the advantageous electrode material 9 of the present invention as previously described, in particular with reference to the inclusion of the conductive additive 19, and/or conductive supports 21, and/or macro pores 23, into an energy storage cell 29 with a conventional two-dimensional current collector 25, 27arrangement.

[0116] Hence, according to an embodiment an energy storage cell 29 including a conventional two-dimensional current collector 25, 27arrangement can be advantageously modified to include the electrode material 9 including conductive additive 19 of an aspect of the present invention as described above. In particular, the electrode material 9 may be pre-mixed such that it additionally includes a conductive additive comprising conductive material 19. For instance, the electrode material 9 may be formed such that it advantageously includes a sufficient number of randomly scattered conductive additive material 19 in the form of particles, fibres, needles, rods, flakes, filaments, plates, ribbons or any other shape known in the art are added to the electrode material 9. The size of the conductive additive material 19 is not limited and they may comprise metal, non-metal, polymer or any other conducting material. Preferably, a layer of electrode material 9 without conductive additive material 19 is located between the separator 7 and the electrode material 9 with conductive additive 19, to advantageously avoid the conductive additive material 19 piercing or bridging the separator] and shortcutting the system.

[0117] Advantageously, the conductive additive material 19 simultaneously enhance both electronic conductivity and mechanical stability of the energy storage cell 29. In particular, the conductive additive material 19 increase electronic conductivity by providing additional electric contact points and additional electron charge transport routes within the electrode material 9, such that for instance electrons are able to travel a reduced distance to reach the active material. Further advantageously, the pre-mixing of the electrode material 9 allows for the use of less binder than in conventional arrangements, as the pre-mixing of the electrolyte with the active material forms a sticky adhesive paste therefore avoiding the need to introduce additional binder in the mix to adhere the electrode material 9 to the current collectors 25, 27 as would be required in conventional applications. This also advantageously allows a higher proportion of active material to be included in the electrode material 9, hence increasing energy density further.

101181 Alternatively, in embodiments in which the electrode material 9 is not pre-mixed to include the electrolyte, the electrode material 9 including active material would be added, for instance as a conventional slurry, and then dried before electrolyte may be added in a subsequent wetting stage.

101191 In use, the conductive additive material 19 provide deeper and more comprehensive conductive penetration of the active material, as on average any location within the electrode layer 9 is likely to be closer to conductive material in the form of the conductive additive material 19 which allows a low resistance travel path for electronic transfer. Hence the electrons experiencing the electric fields within the energy storage cell 29 have lower resistance and higher conductivity in the form of more and faster travel paths, as compared to state of the art arrangements.

[0120] Additionally, the advantageous effect of the conductive material 19 may be further enhanced by applying a pre-coating stage in which the conductive additive 19 itself is coated with a thin layer of highly conductive material, thereby further increase in electrical conductivity of the conductive additive 19.

[0121] Alternatively or additionally, the electrode layers and/or electrode material 9 may comprise conductive supports 21. Advantageously, the conductive supports 21 according to embodiments of the present invention simultaneously provide additional structural support and enhanced electrical conductivity to the energy storage cell 1 or energy storage device. In particular, the conductive supports 21 increase electronic conductivity by 1 0 providing additional electric contact points and additional electron charge transport routes within the electrode material 9, such that charge carriers are able to travel faster and with reduced distance to reach the active material and current collectors 25, 27. For instance, the charge carriers only have to reach the nearest conductive support 21 to find a low resistance and short distance route between the active material and current collector 25, 27.

[0122] Further, the conductive supports 21 are configured to be sufficiently dimensioned and of an appropriate material to provide physical structural support and mechanical stability to the energy storage cell 29 or energy storage device. For instance, the conductive supports 21 may comprise metals, non-metals, polymers or any other conducting material or a combination thereof. The conductive supports 21 may be arranged as, for instance, a pre-formed mesh, grid, scaffold or gouge configuration. Further, the conductive supports 21 may take any suitable shape, size or number within the electrode material 9 such that the conductive supports 21 advantageously provide structural support and additional functioning electronic conductivity.

[0123] The conductive supports 21 are located within the electrode layers and the electrode material 9 therein. Preferably, the conductive supports 21 extend substantially across the entire width, depth and/or height of each electrode layer, or any combination thereat to advantageously provide considerable structural support and enhanced conductivity throughout the electrode layer and energy storage cell 29 as a whole. Further, the conductive supports 21 may be positioned to extend either parallel to or perpendicular to the extension of the electrode layer of the energy storage cell 29.

[0124] In a preferred example, for instance as shown in Figure 16, the conductive supports extend across the width of the energy storage cell 29. Additionally, a conductive support 21 may be configured such that it extends in a continuous manner between two or more adjacent compartments 15. Such a configuration advantageously provides even further enhanced structural support across the entire energy storage cell 29 or energy storage device. In particular, this may be achieved using a conductive support 21 in the form of a coil. As shown in Figure 16, such a configuration of the conductive support 21 appears as a zig-zag or 'w' shaped arrangement when viewed in cross section through the energy storage cell 29.

[0125] Alternatively or additionally, the conductive supports 21 may take the form of rods, straight or otherwise. Alternatively or additionally, the conductive supports 21 may take the form of conductive foam, which may for instance be added in any direction within the energy storage cell 29, so as to provide even further enhanced electron transport conductivity.

[0126] The addition of the conductive supports 21 further enhances the advantageous ability of the energy storage cell 29 to accommodate volumetric and localised swelling of the electrode material 9 that is common in use, for instance over long charge and discharge cycles. In particular, the additional mechanical stability and structural support provided by the conductive supports 21 allows for increased flexibility and elasticity in the energy storage cell 29 which will accommodate any such volumetric changes in use. This can be especially useful for anodes in the field of batteries. This advantage may be particularly evident with the coil embodiment, but will also be significantly exhibited by other shapes and configurations.

[0127] In use, the conductive supports 21 simultaneously structurally support the energy storage cell 29, and provide deeper and more comprehensive conductive penetration of the active material, as on average any location within the electrode layer 9 is likely to be closer to conductive material in the form of the conductive support 21 which allows a low resistance travel path electronic transfer. Hence the electrons experiencing the electric fields within the energy storage cell 1 have lower resistance and higher conductivity in the form of more and faster travel paths.

[0128] Both the conductive additive 19 and conductive supports 21 individually advantageously introduce additional electrical contact points, more charge carrier transport routes, and enhanced electrical conductivity within the electrode material 9 of the energy storage cells 29. The considerably enhanced conductivity provided by the conductive additive 19 and conductive supports 21, whether considered alone or together, allows even further significant increases in the thickness of the electrode layers to be achieved, and substantially removes the limitation to electrode thickness in the art in which beyond a certain thickness the ionic and electronic conductivity between distant areas of the active material and the current collectors becomes too low. Further, both the conductive additive 19 and conductive supports 21 as advantageously provide increased mechanical stability to the energy storage cell 29 or energy storage device. Hence, as such the combination of the conductive additive 19 and the conductive supports 21 in a single energy storage cell 29 synergistically provides a dramatic increase in the conductivity of the energy storage cell 29, allowing for substantially increased electrode thickness as compared to state of the art implementations, and hence providing considerably higher energy density in the final electrode storage cell 1 or device.

[0129] It is noted that by including the conductive additive 19 and/or the conductive supports 21 in the electrode material 9 of the conventional two-dimensional current collector configuration, embodiments of the invention in effect advantageously transform the two-dimensional current collectors 25, 27 into three-dimensional current collectors. In particular, each of the conductive additive 19 and/or the conductive supports 21 in effect become an advantageous extension of the current collectors 25, 27 into the electrode material 9. Hence embodiments of the invention may be considered to advantageously convert a conventional two-dimensional current collector arrangement into a three-dimensional current collector arrangement through the addition of the electrode material 9 including the conductive additive 19 and/or the conductive supports 21.

[0130] Further, embodiments of the present invention may have an enhanced conductivity electrode material 9 by additionally including a second pore channel structure at the macro scale, the dimensions of which would be larger than the conventional nano and micro scale pores known in the art. In particular, macro scale pores or channels 23 may be provided within the electrode material 9 in the direction extending substantially between the cathode current collector 25 or anode current collector 27 and the separator 7, for instance vertically between the two. In use, the macro pore channel 23 structure provided in the active material of the electrode material 9 will be filled with electrolyte. The size and extent of the macro scale pores or channels 23 of the second pore channel structure is governed by the porosity of the existing single micro or nano scale pore structure of the active material, with for instance the recommended volume fraction of the second pore channel structure being equal to or lower than the porosity of the existing single micro or nano scale pore structure of the active material. Accordingly, the size and distance between macro scale pores or channels 23 of the second pore channel structure may be determined based on the original porosity of the active material. For instance, the size of the pores or channels 23 of the second pore channel structure may be between a few microns to hundreds of microns.

[0131] A specific embodiment is shown in Figure 16, wherein the electrode material 9 has macro pores 23 formed within the electrode layers. These macro pores 23 may be provided in combination with the conductive additive 19 and conductive support 21 arrangements as described previously. However, the number of macro pores 23 added to or included in the electrode material 9 may be large or small. Further, the specific embodiment of Figure 16 shows the macro pore channel 23 structure as being straight line bore holes in the substantially vertical direction, as for instance may be formed by a cylindrical rod. However, other shapes, configurations and orientations may be used in embodiments of the present invention. In particular, the macro pores 23 can be formed in any direction, shape, length or configuration. Further, the macro pores 23 can be formed in any shape, such as for instance a cone shape, which as will be described below further improve the wettability of the pores and penetration of the electrolyte, for instance by the capillary reaction effect.

[0132] Advantageously, the macro pores 23 may provide one or more distinct advantages, each of which considerably improves the conductivity of the energy storage cells 29, in particular by improving ionic conductivity. Firstly, relative to the conventional micro or nano scale pore arrangement of active material as is known in the art, the active material of the electrode material 9 may provide an advantageously improved surface area of active material in contact with electrolyte, whilst also sacrificing only a small amount of active material in the provision of the macro pore channel 23 structure.

[0133] Secondly, the electrolyte penetration into the active material may be considerably improved, thereby allowing a faster, more efficient and less resistant transfer of ions to and from the active material and the electrolyte. In particular, in conventional micro or nano scale pore structures, it is difficult to ensure that the electrolyte added to the micro or nano scale pores will be effective in penetrating deep into the active material, with for instance the deepest or furthest parts of the active material from the current collectors 25, 27 being 'dry' and therefore of significantly reduced or no ion transfer capability.

[0134] Thirdly, the macro pores 23 may act in the manner of an ionic highway, providing a fast, low resistance and short distance travel path between the separator 7, cathode current collector 25 and anode current collector 29 and the active material. In particular, relative to conventional micro or nano pore structures, the route from the deepest or furthest part of the active material to the separator 7 is considerably shorter and less tortuous.

[0135] Fourthly, when the energy storage cell 29 is in use, the macro pore channel 23 structure may significantly reduce the likelihood and occurrence of electrolyte drainage, electrolyte drying and ionic conductivity reduction, in particular because the macro pore channel 23 structures additionally function as electrolyte reservoirs. This may be particular advantageous during long cycles of use of the energy storage cell 29, and may significantly increase the functioning lifetime of the energy storage cell 29 in embodiments of the present invention as compared to the state of the art. This advantage is of particular importance in the application of embodiments of the present invention to supercapacitors in which energy storage is achieved using the dual-layer effect, and/or Faradic reactions, in the pores of the active material at the interface between the active material and the electrolyte, and which suffer distinctly from the problem of insufficient electrolyte penetration into the pores of the active material. The macro pores 23 may advantageously overcome these problems through the provision of electrolyte reservoirs which serve to improve the wettability of the pores and penetration of the electrolyte, and hence create greater surface area contact between the active material and the electrolyte and therefore provide a higher energy storage capacity to the supercapacitor. In summary, amongst other advantages, the macro pores 23 of embodiments of the prevent invention may allow a larger portion of active pore sites to be accessed by the electrolyte, and hence significantly improve energy and power density of energy storage cells, hence thereby providing a more volumetrically efficient energy storage cell 29 capable of the same power output and energy storage as considerably larger state of the art energy storage cells.

[0136] In use, when charge transfer is occurring at the interface between the micro and nano scale pores within the active material, the charge needs only to reach the macro pore channel 23 structure to find a low resistance and short path distance to and from the separator 7. Hence, by analogy the macro pore channel 23 structure supplements the original micro and nano scale pore structure in the manner of a motorway as compared to smaller slower roads leading to the motorway. Further, if and when electrolyte drying begins to occur at a pore site in the active material, the capillary reaction effect will draw electrolyte from the macro pores 23 which are therefore acting as electrolyte reservoirs. This is particularly advantageous for during long use cycles. Hence the lifetime of the energy storage cell 29 is improved.

[0137] An advantageous method of forming the macro scale pores will be described further below. The macro pore channel 23 structure is advantageously fast and simple to form in the electrode material 9, or to apply retrospectively to a formed electrode material 9.

[0138] It is noted that whilst Figure 16 shows the electrode material 9 in combination with the conductive additive material 19, the conductive supports 21 and the macro pores, as described above the electrode material 9 may be combined with any one of these advantageous features individually, or any combination of some or all of them together. [0139] An advantageous method of constructing a two dimensional current collector including the electrode material 9 of the present invention will now be described.

[0140] Once a conventional two-dimensional cathode current collector 25 or anode current collector 27 has been chosen and is in location, electrode material 9 may be applied to the current collector 25, 27.

[0141] In embodiments in which the conductive supports 21 are to be included in the energy storage cell 29, this may optionally be the next stage of formation. In particular, regardless of the shape of conductive support 21 to be added, they may be added to the current collector 25, 27.

[0142] Preferably, the conductive supports 21 extend substantially across the width, depth and/or height of each electrode layer, or any combination thereof, to advantageously provide considerable structural support and enhanced conductivity throughout the energy storage cell 29 as a whole. The conductive supports 21 may be located using pick and place machinery, and may for instance include steps to adhere the conductive supports 21 to the current collector 25, 27. Alternatively, the conductive supports 21 may be held in position before being removed at a later stage, for instance after application of the electrode material 9.

[0143] The electrode material 9, in accordance with any previous description thereof in the present disclosure, may then be added to the combined current collector 25, 27 and conductive support 21 arrangement. The electrode material 9 may be formed by premixing of the active material and the electrolyte to form a paste. Advantageously, the premixing of the active material with the electrolyte in this manner provides good penetration of the electrolyte into and within the active material, thereby increasing conductivity as compared with alternate conventional methods of adding electrolyte to active material such as pouring liquid electrolyte into the solid active material. Alternatively, in embodiments in which the electrode material 9 is not pre-mixed to include the electrolyte, the electrode material 9 including active material would be added, for instance as a conventional slurry, and then dried before electrolyte may be added in a subsequent wetting stage.

[0144] As previously described, an amount of advantageous conductive additive 19 may also be added to the active material and the electrolyte in forming the electrode material 9 paste. The size and material of these conductive additives 19 may be as previously described. An appropriate amount of conductive additive 19 should be added such that conductivity in the electrode material 9 is increased without adding so much that the amount of active material is effectively diluted and energy density therefore decreases. [0145] Advantageously, the pre-mixing of the conductive additive 19 into the electrode material 9 is both simple and highly effective as it provides good penetration of the conductive additive within the electrode material 9. Further, a pre-mixed electrode material 9 is advantageously fast and simple to apply to the other components.

[0146] The electrode material 9 so formed may then be deposited on or compressed onto the current collector 25, 27 in an advantageously simple step. In particular, the electrode material 9 may therefore be applied such that it surrounds the carefully positioned conductive supports 21. The electrode material 9 may also be applied in any appropriate way. In cases in which a binder is included in the pre-mixed electrode material 9, a drying stage may need to be performed before or after the electrode material 9 is applied.

[0147] Advantageously, the application of the electrode material 9 as a pre-mixed paste to the arrangement of the current collector 25, 27 and conductive supports 21 provides significantly improved even application as compared to conventional methods of electrode material application. In particular, the deposition under gravity and/or compression under additional force causes the electrode material 9 to coat the current collectors 25, 27 and conductive supports 21 such that their entire surface area is in contact with the electrode material 9. This provides significantly enhanced conductivity within the energy storage cell 29, as well as thereby allowing the formation of considerably thicker electrodes 11, 13 as compared to the state of the art. Such advantages may be particularly beneficial for superca pacitor applications.

[0148] Further, as described in the background section, conventional slurry coating techniques for forming electrodes require multiple repeated stages of application, including layering, drying, cutting and forming into stacks etc. Advantageously, there may be a significant reduction in the number of steps required to form the desired energy storage cell 29, and hence a significant improvement in speed of formation. In particular, in the first instance the electrode material 9 can be applied in a single step, as described above, to the current collectors 25, 27.

[0149] Further, in the conventional slurry coating technique for electrode formation as known in the art, the repeated application stages and the requirement for drying lead to a significantly weaker electrode, disadvantageously having less mechanical stability leading to brittleness, cracks and delamination. This also puts a limit on the thickness of the electrodes that can be formed. As described above, various embodiments of the energy storage cell 29 of the present invention allow for the ability to provide thicker electrode layers. The advantageous reduction of the electrode material 9 application into a single stage and removal of the requirement to apply the electrode material in multiple layering and drying stages also significantly improves the structural integrity of the electrode material 9 as a whole, as it forms and sets as a single entity with a far lower propensity to crack and substantially eliminates the problem of delamination. This advantageously allows significantly thicker electrode material 9 layers to be formed as compared to the state of the art.

[0150] The ability to form thicker electrodes as provided by embodiments of the present invention also allows for fewer energy storage cell 29 layers in any given size of energy storage device as compared with the state of the art. In particular, as more of the energy storage cell 1 or device can be dedicated to active material in the electrode material 9, thicker layers of electrode material 9 can be formed, and hence fewer energy storage cells 1 are needed for any particular size and hence fewer current collectors 25, 27 and separators 7 as required for each energy storage cell 29 will be included within the final energy storage device. Additionally, this advantage also allows for an improved speed of manufacture as fewer processing steps will be required to form an energy storage cell 29 of any given size, as any given size of energy storage device according to embodiments of the present invention will include fewer components than conventional energy storage devices of the same size. Further still, this reduction in the number of components that need to be located and assembled provides for a method of improved reliability, as there are fewer potential failure points in the locating and assembling of the energy storage device as compared to the more complex and delicate arrangements of the state of the art.

[0151] In the above preferred arrangement, the electrode material 9 is added after the conductive supports 21. Alternatively, the electrode material 9 may be added before the conductive supports 21, in which case the conductive supports 21 must then be introduced to or forced through the electrode material 9. Further, it is noted that the conductive supports 21 may also be advantageously added to a conventional electrode material 9 which does not include the conductive additive 19. In such instance, the method or application of the electrode material 9 and conductive supports 21 as described above is equally applicable.

[0152] As a result of the above method, the electrode layers as shown in the specific embodiment of Figure 16 may be formed.

[0153] In another embodiment of the method, macro pores 23, as previously described in the present disclosure, may then be quickly and easily added to current collector 25, 27, electrode material 9, and/or conductive support 21 arrangement. The macro pores 23 may be formed in the electrode material 9 by pressing a pore mould of the desired shape and configuration into the exposed surface of the electrode material 9. For instance, this second mould may be formed of a series of cylindrical rods which when pressed into the surface of the electrode material 9 form the required macro pore 23 channels in the respective locations of the electrode material 9. The macro pores 23 can be formed in any direction, shape, length or configuration, and as determined by the configuration of the pore mould. For instance, the macro pores 23 may extend substantially through an entire dimensional direction of the electrode material 9, such as through the height of the electrode material 9 in a direction perpendicular to the separator 7 and between the current collector 25, 27 and the separator 7. Once the macro pores 23 are formed, the pore mould is then removed from the electrode material 9 leaving the created macro pore channel 23 structure present in the electrode material 9. Either next or at a later stage, these macro pores 23 are may be filled with electrolyte, in the process conventionally known as 'wetting' of the electrode material 9.

[0154] The pore mould for forming the macro pore channel 23 structure may be heated, or unheated, or may take any other suitable form which allows for formation of the macro pores 23 in the electrode material 9.

[0155] Advantageously, as previously described, the macro pore channel 23 structure provides significantly improved electrolyte wetting of the electrode material 9 during the formation stage. In particular, the macro pores 23 penetrating within the electrode material 9, and in some cases substantially through the electrode material 9, provide reservoirs of electrolyte which serve to facilitate more effective penetration of the electrolyte into the active material by capillary action. In particular, the capillary action of the electrolyte from the macro pores 23 serves to penetrate deeper into the conventional nano and micro scale pores of the active material, in a more even and substantial manner than would be achieved by relying on capillary action through only the conventional nano or micro scale pores.

[0156] Alternatively, the macro pores 23 could be formed in the electrode material 9 before it is applied to the current collectors 25, 27. For instance, the macro pore channel 23 structure could be formed in the electrode material 9 by distributing the active material throughout a pre-formed structure dimensioned and located to form the macro pores 23, wherein the pre-formed structure is then subsequently removed using a chemical process or any other removal technique known in the art. Alternatively, the pre-formed structure may be located on the current collectors 25, 27, either before or after any conductive supports 21 have been added, and the electrode material 9 may be applied to the current collectors 25, 27 and around the pre-formed structure which is then subsequently removed by chemical, physical or other known processes.

[0157] As a result of the above method, the electrode layers as shown in the specific embodiment of Figure 16 may be formed.

[0158] Accordingly, the above methods create a single electrode layer with the method being equally applicable to the creation of both the cathode current collector 25 and the anode current collector 27. A separator 7 may then be located as appropriate on the electrode layer. Preferably, in embodiments in which the electrode material 9 includes conductive additive material 19, as previously described a layer of electrode material 9 without conductive additive material 19 is also applied to the arrangement before the separator] is located on the electrode layer. Finally, two electrode layers as formed by the above processes may then be combined such that they are formed into a single energy storage cell 29 as depicted in Figure 16. The manner of connection and integration of these two electrode layers to form the final energy storage cell 29 would be understood by the skilled person and is not described further here. A plurality of such energy storage cells 29 may then be combined to form an energy storage device of multiple layers.

The processes described above advantageously provide a fast, simple, and inexpensive method for forming an energy storage cell 29 in accordance with embodiments of the present invention. Such an advantageous method is particularly important in the field of energy storage cells 1 and devices in which a high proportion of overall costs is attributed to the manufacturing process. The above processes are particularly advantageous when it comes to the formation of thick electrodes, which are difficult to achieve using the conventional slurry coating methods. The advantageous simplification of the process for forming energy storage cells 29 whilst simultaneously allowing for thicker electrode layers as provided for by embodiments of the present invention allows for cheaper manufacturing equipment and faster production as compared to state of the art configurations. Further, as previously outlined, the final energy storage cell 29 or device so formed is capable of including thicker electrode layers, enhanced conductivity and a higher energy density than state of the art energy storage cells 29 or devices.

Claims

47 Claims 1. A method of forming an energy storage cell having a monolithic corrugated current collector in a three-dimensional configuration, comprising forming the corrugated current collector in a three-dimensional configuration.
2. The method of claim 1, wherein the forming the corrugated current collector in a three-dimensional configuration comprises forming the corrugated current collector in a three-dimensional configuration from a unitary sheet of current collector material.
3. The method of any preceding claim, wherein the forming the corrugated current collector in a three-dimensional configuration comprises folding.
4. The method of any preceding claim, wherein the forming the corrugated current collector in a three-dimensional configuration comprises using a shape forming element, preferably a mould, and optionally pressing or stamping the corrugated current collector into the three-dimensional configuration.
5. The method of any preceding claim, wherein forming the corrugated current collector in a three-dimensional configuration comprises extrusion and/or heating and/or deposition.
6. The method of any preceding claim, wherein the forming of the corrugated current collector comprises forming the corrugated current collector into at least one compartment.
7. The method of claim 6, further comprising inserting at least one conductive support member, for providing structural support to the energy storage cell, in the corrugated current collector after forming the corrugated current collector in a three-dimensional configuration, such that the at least one conductive support member passes through the compartment or compartments of the corrugated current collector.
8. The method of claim 7, wherein the at least one conductive support member is a coil, and the inserting of the at least one coil into the corrugated current collector comprises interconnecting the coil with sides of the at least one compartment such that it extends across the compartment, or interconnecting the coil with sides of a plurality of the compartments such that it extends across a plurality of the compartments.
9. The method of claim 7, wherein the at least one conductive support member is a rod, and the inserting of the at least one rod into the corrugated current collector comprises passing the rod through sides of the at least one compartment such that it extends across the compartment, or passing the rod through a plurality of the compartments such that it extends across a plurality of the compartments.
10.The method of claim 7, wherein the at least one conductive support member is a foam, and the inserting of the foam into the corrugated current collector comprises locating the foam along the at least one compartment such that it extends along the compartment, or passing the foam along a plurality of the compartments such that it extends along the plurality of the compartments.
11.The method of any one of claims 6 to 10, further comprising inserting electrode material for forming a cathode or anode in the at least one compartment or plurality of compartments, after forming the corrugated current collector in a three-dimensional configuration, such that the shape and thickness of the at least one compartment or plurality of compartments is used to define the shape and thickness of the electrode material in the energy storage cell.
12.The method of claim 9 when dependent on claim 7, wherein the introducing the electrode material to the compartment or plurality of compartments is after the inserting at least one conductive support member into the corrugated current collector, and comprises substantially filling the compartment or plurality of compartments with electrode material, and substantially coating the conductive support member or plurality of conductive support members with electrode material.
13.The method of claim 9 when dependent on claim 7, wherein the introducing the electrode material to the compartment or plurality of compartments is before the inserting at least one conductive support member into the corrugated current collector, and is such that the electrode material substantially fills the compartment or plurality of compartments, and comprises locating the at least one conductive support member in the electrode material such that the electrode material substantially coats the conductive support member or plurality of conductive support members.
14. The method of claim 11 to 13, further comprising forming the electrode material by mixing an active material, an electrolyte and a conductive additive before locating the electrode material in the at least one compartment, wherein the conductive additive optionally comprises particles fibres, needles, rods, flakes, filaments, plates or ribbons, or any combination thereof.
15. The method of any of claims 11 to 14, further comprising forming macro pore channels in the electrode material for containing electrolyte.
16. The method of claim 15, wherein the forming the macro pore channels in the electrode is before the locating the electrode material in the at least one compartment.
17.The method of claim 15, wherein the forming the macro pore channels in the electrode is after the locating the electrode material in the at least one compartment.
18.The method of any one of claims 15 to 17, wherein forming the macro pore channels comprises pressing a pore mould into the electrode material, and subsequently removing the pore mould from the electrode material.
19.The method of any one of claims 15 to 17, wherein forming the macro pore channels comprises introducing the electrode material to a pore mould, and subsequently removing the pore mould from the electrode material.
20.The method of any one of claims 15 to 19, wherein the forming the macro pore channels is such that the macro pore channels extend substantially through an entire dimensional direction of the electrode material.
21.The method of any one of claims 11 to 20, wherein forming the energy storage cell comprises forming a cathode layer or anode layer by locating a separator therein such that the electrode material is between the corrugated current collector and the separator.
22. The method of claim 21, wherein the locating of the separator is after: a. the locating of the electrode material in the at least one compartment; b. the inserting of the at least one conductive support into the corrugated current collector; c. the forming the macro pore channels in the electrode material.
23.The method of claim 22 when dependent on claim 14, wherein the locating of the separator is after: a. locating a layer of electrode material without conductive additive in the energy storage cell such that it will be located between the electrode material comprising conductive additive and the separator once the separator is located.
24.The method of any one of claims 11 to 23 when dependent on claim 4, wherein the corrugated current collector is within the shape forming element or a support element during: a. the locating of the electrode material in the at least one compartment; and/or b. the inserting of the at least one conductive support into the corrugated current collector; and/or c. the forming the macro pore channels in the electrode material.
25. The method of any one of claims 6 to 24, further comprising forming the corrugated current collector in a tray configuration, or a chevron configuration, or a wave configuration, wherein the forming at least one compartment comprises forming the compartment into a tray configuration, or a chevron configuration, or a wave configuration, and wherein there are a plurality of compartments forming each of the compartments into a tray configuration, or a chevron configuration, or a wave configuration.
26. The method of any preceding claim, further including forming an electrical tab, for connection to external components, from a part of the corrugated current collector and wherein the tab may be at any surface or location of the corrugated current collector, and optionally wherein when corrugated current collector is a cathode the tab is formed on one side of the energy storage device and when the corrugated current collector is an anode the tab is formed on a different side of the energy storage device.
27. A method of forming an energy storage device comprising forming a plurality of energy storage cells according to the method of any preceding claim, wherein the energy storage device is preferably a battery, capacitor, supercapacitor, ultracapacitor, or hybrid type energy storage device.
28. An energy storage cell comprising a monolithic corrugated current collector in a three-dimensional configuration.
29.The energy storage cell of claim 28, wherein the monolithic corrugated current collector is formed from a unitary sheet of current collector material.
30. The energy storage cell of claim any one of claims 28 to 29, wherein the corrugated current collector comprises at least one compartment.
31. The energy storage cell of claim 30, wherein the energy storage cell comprises at least one conductive support member, for providing structural support to the energy storage cell, located in the corrugated current collector.
32.The energy storage cell of claim 31, wherein the at least one conductive support member passes through the compartment or compartments of the corrugated current collector.
33.The energy storage cell of claim 31, wherein the at least one conductive support member is a coil interconnected with sides of the at least one compartment such that it extends across the compartment, or interconnected with sides of a plurality of the compartments such that it extends across a plurality of the compartments.
34.The energy storage cell of claim 31, wherein the at least one conductive support member is a rod passing through sides of the at least one compartment such that it extends across the compartment, or passing through a plurality of the compartments such that it extends across a plurality of the compartments.
35.The energy storage cell of claim 31, wherein the at least one conductive support member is a foam located along the at least one compartment such that it extends along the length of the compartment, or located foam along a plurality of the compartments such that it extends along the length of a plurality of the compartments.
36.The energy storage cell of any one of claims 30 to 35, wherein the at least one compartment includes electrode material for forming a cathode or anode, wherein the shape and thickness of the electrode material in the energy storage cell is defined by the shape and thickness of the at least one compartment.
37. The energy storage cell of claim 36, wherein the electrode material substantially fills the compartment or plurality of compartments.
38. The energy storage cell of claim 37 when dependent on claim 31, wherein the electrode material substantially coats the conductive support member or plurality of conductive support members.
39. The energy storage cell of any one of claims 36 to 38, wherein the electrode material comprises an active material, an electrolyte and a conductive additive, wherein the conductive additive optionally comprises particles, fibres, needles, rods, flakes, filaments, plates or ribbons, or any combination thereof.
40. The energy storage cell of any one of claims 36 to 39, further comprising a layer of electrode material without conductive additive located between the separator and the electrode material comprising conductive additive.
41. The energy storage cell of any one of claims 36 to 39, wherein the electrode material further comprises macro pore channels for containing electrolyte.
42.The energy storage cell of claim 41, wherein the macro pore channels extend substantially through an entire dimensional direction of the electrode material.
43. The energy storage cell of claim 41 or 42, wherein the macro pore channels extend substantially between the corrugated current collector and a separator.
44. The energy storage cell of any one of claims 36 to 43, comprising a cathode layer or anode layer comprising the electrode material located between a separator and the respective corrugated current collector for the cathode or anode.
45.The energy storage cell of claim 44, wherein the current collector extends across substantially the length of the energy storage cell and is the sole current collector for the respective cathode layer or anode layer.
46.The energy storage cell of any one of claims 43 to 45, wherein the at least one compartment substantially encases the electrode material located between itself and the separator.
47. The energy storage cell of any one of claims 28 to 46, wherein a part of the corrugated current collector is formed into an electrical tab, for connection to external components, at any surface or location of the corrugated current collector, and optionally wherein when corrugated current collector is a cathode the tab is formed on one side of the energy storage device and when the corrugated current collector is an anode the tab is formed on a different side of the energy storage device.
48. The energy storage cell of any one of claims 28 to 47 wherein the corrugated current collector is in a tray configuration, or a chevron configuration, or a wave configuration, wherein at least one compartment is a tray configuration, or a chevron configuration, or a wave configuration.
49. The energy storage cell of any one of claims 28 to 48 wherein the corrugated current collector is in a textured surface configuration, wherein at least one compartment is formed by indentations between bumps or ridges.
SO. An energy storage device comprising a plurality of energy storage cells as defined in any one of claims 28 to 49, wherein the energy storage device is preferably a battery, capacitor, supercapacitor, ultracapacitor, or hybrid type of energy storage device.
51.An energy storage cell comprising a current collector, a separator and electrode material for forming a cathode or anode located between the current collector and the separator; further comprising at least one conductive support member, for providing structural support to the energy storage cell, located in the electrode material.
52. The energy storage cell of claim 51, wherein the conductive support member extends across substantially an entire dimensional direction of the electrode material.
53.The energy storage cell of claim 52, wherein the dimensional direction is height and/or width, such that the conductive support member extends across substantially the entire energy storage cell.
54. The energy storage cell of any one of claims 51 to 53, wherein the conductive support member is a coil.
55. The energy storage cell of any one of claims 51 to 54, wherein the conductive support member is a rod.
56. The energy storage cell of any one of claims 51 to 55, wherein the conductive support member is a foam.
57. The energy storage cell of any one of claims 51 to 56, wherein the electrode material substantially coats the conductive support member or plurality of conductive support members.
58. The energy storage cell of any one of claims 51 to 57, wherein the electrode material comprises an active material, an electrolyte and a conductive additive.
59.The energy storage cell of claim 58, wherein the conductive additive comprises particles, fibres, needles, rods, flakes, filaments, plates or ribbons, or any combination thereof.
60. The energy storage cell of any one of claims 51 to 59, wherein the electrode material comprises macro pore channels for containing electrolyte.
61.The energy storage cell of claim 60, wherein the macro pore channels extend substantially through an entire dimensional direction of the electrode material.
62.The energy storage cell of claim 61, wherein the macro pore channels extend substantially between the current collector and the separator.
63.An energy storage cell comprising a current collector, a separator and electrode material for forming a cathode or anode located between the current collector and the separator; wherein the electrode material comprises an active material, an electrolyte and a conductive additive.
64.The energy storage cell of claim 63, wherein the conductive additive comprises particles, fibres, needles, rods, flakes, filaments, plates or ribbons, or any combination thereof.
65. The energy storage cell of any one of claims 63 or 64, further comprising a layer of electrode material without conductive additive located between the separator and the electrode material comprising conductive additive.
66.The energy storage cell of any one of claims 63 to 65, further comprising at least one conductive support member, for providing structural support to the energy storage cell, located in the electrode material.
67. The energy storage cell of claim 66, wherein the conductive support member extends across substantially an entire dimensional direction of the electrode material, and optionally wherein the conductive support member extends across substantially the entire energy storage cell.
68. The energy storage cell of any one of claims 66 or 67, wherein the conductive support member is a coil, or a rod or a foam.
69. The energy storage cell of any one of claims 66 to 68, wherein the electrode material substantially coats the conductive support member or plurality of conductive support members.
70.An energy storage cell comprising a current collector, a separator and electrode material for forming a cathode or anode located between the current collector and the separator; wherein the electrode material comprises macro pore channels for containing electrolyte.
71.The energy storage cell of claim 70, wherein the macro pore channels extend substantially through an entire dimensional direction of the electrode material.
72.The energy storage cell of claim 71, wherein the macro pore channels extend substantially between the current collector and the separator.
73.The energy storage cell of any one of claims 70 to 72, further comprising at least one conductive support member, for providing structural support to the energy storage cell, located in the electrode material.
74. The energy storage cell of claim 73, wherein the conductive support member extends across substantially an entire dimensional direction of the electrode material, and optionally wherein the conductive support member extends across substantially the entire energy storage cell.
75. The energy storage cell of any one of claims 73 or 74, wherein the conductive support member is a coil, or a rod or a foam.
76. The energy storage cell of any one of claims 73 to 75, wherein the electrode material substantially coats the conductive support member or plurality of conductive support members.
77. The energy storage cell of any one of claims 70 to 76, wherein the electrode material comprises an active material, an electrolyte and a conductive additive.
78.The energy storage cell of claim 77, wherein the conductive additive comprises particles, fibres, needles, rods, flakes, filaments, plates or ribbons, or any combination thereof.
79. An energy storage device comprising a plurality of energy storage cells as defined in any one of claims 51 to 78, wherein the energy storage device is preferably a battery, capacitor, supercapacitor, ultracapacitor, or hybrid type of energy storage device.