Interdigitated finger coextrusion

Co-extrusion of interdigitated fingers

INTERDIGITATED FINGER COEXTRUSION

The invention relates to a co-extrusion device and method for interdigitated fingers.

Many devices such as batteries, fuel cells, electrical interconnections, and other devices can benefit from dissimilar materials in closely spaced interdigitated strips. The term "stripe" as used here means a line or other shape that only contains the material. It does not mix with adjacent strips of other materials.

When trying to produce closely spaced interdigitated belts, problems can arise. In one method, compressed flow polymerization is used to produce the fine properties of the paste-like functional material. Such methods are, for example, US Patent No. 7,765,949 filed on August 3, 2010, and US Patent No. 7,799,371 filed on September 21, 2010. The methods in these patents are related to combining materials into a "co-laminar flow", in which three laminar flows of two different materials are gathered together to form a flow, but the two materials are not Do not mix together. This method can meet the application of tens of micrometer grade characteristics arranged on a centimeter-sized pitch. For example, a solar cell may have 156 mm and about 80 grid lines, each of which is about 50 microns wide and separated from an adjacent grid line by approximately 2 mm.

In contrast, the interdigital structure required by the electrode design of the energy storage device may require micrometer scale characteristics interleaved on the micrometer scale. For example, a typical cathode structure may include an interleaved structure with a width of 5 microns and a height of 100 microns. An electrode structure may be 300mm wide and 60,000 interleaved fingers of different materials. It is not practical to dispense these materials from different nozzles or from multiple material slot containers.

The present invention relates to a co-extrusion device, which has: at least one first fluid inlet for receiving a first material; at least one second fluid inlet for receiving a second material; and a first combining channel configured to Receiving the first material and the second material, and combining the first material and the second material into a first combined flow flowing in a first direction; a dividing channel configured to receive the first combined flow, and Dividing the first combined flow into at least two divided flows flowing in a second direction at least partially perpendicular to the first direction, wherein each divided flow includes the first and second materials; a second combined channel is configured Is configured to receive the divided flow and combine the divided flow into a second combined flow that flows in the first direction; and at least one outlet port is configured to allow the material to exit the device as a single flow. The present invention is also related to a method for depositing a structure comprising interdigitated materials, comprising: combining at least two flows of materials in a first direction into a first combined flow; and turning the first combined flow toward the second The direction is divided to generate at least two separated flows, wherein the second direction is perpendicular to the first direction; and the two separated flows are combined into a second combined flow.

In order to achieve an interdigital structure with micron characteristics on a micron scale, two or more flows can be combined and converged, and the combined flow can be divided into separate combined flows and then combined and further converged in repeated stages. This discussion is called a fluid process, which produces interdigitated flows of different fluids as "fluid folds." This discussion is also referred to as a fluid structure, which performs combination, convergence, division, and recombination, etc., as a "folding series."

The term "convergence" as used herein refers to combining the flows of two or more different fluids to form a combined flow. The combined flow has a lateral extension through the width of the combined flow, which is at least smaller than the combined side before the flow is combined. To extend. Generally, the width of the combined flow after convergence has a lateral extension approximately equal to the lateral extension of one of the passing flows before the combination. For example, if the combined flow includes a "strip" or finger, each of which has material A and material B, then the combined flow has a lateral extension dimension X. When the flow is divided and recombined, there will be two interlaced strips containing material A and material B. The lateral extension of this flow is the same as the aforementioned lateral extension X.

Figure 1 shows a cross-sectional view of the flow of two materials. All flow directions in Figure 1 are perpendicular to the page. All flow lines are displayed in cross-sections running from the page. Material A, 10 and material B, 12 flow in stage 14 respectively. Then in stage 16 the first combined flow is formed. This flow converges in phase 18. It should be mentioned that the combination and convergence can occur simultaneously or in stages in this series.

In stage 20, the combined flow system is divided into two separate combined flows. It should be noted that this series is three-dimensional, so the division is generated in the direction perpendicular to the direction of the flow and the initial combination and convergence, that is, above and below the figure.

The two combined flows move separately from each other in stage 22 and are guided to approach sideways. In stage 24, the two separate combined streams are combined into a second combined stream and then converge in stage 26. This combined stream is divided again in a similar or identical form to the stage 20 in the stage 28, separated in the stage 30 and then recombined in the stage 32. In stage 34 the combined flow is then converged. Although this process can be repeated as many times as needed, it is only limited by the material properties and keeps separate from each other during the combination without complete mixing, but the combined flow will run out of the series through the outlet orifice at some points. And become a single flow. One of the advantages of this technology is that it can produce smaller and more material features than the channels for conveying such fluids.

Figure 2 shows an embodiment of this series. The first material enters the train through the channel 40 and the second material enters the train through the channel 42. It should be noted that these channels are called separation channels. Because they separate or maintain the separation between flows, they may bend to one side or the other and change height. The two flow lines are combined using a combining channel 44. As described above, the combined channel has a converging zone 46 in which the combined flow is compressed or converged into a channel having a lateral extension approximately equal to that of the separation channel 40 or 42.

The combined flow is divided into two separate combined flows at the intersection of the combined channel 46 and the divided channels 50 and 48. As shown in FIG. 2, the dividing channel extends the direction perpendicular to the combined flow in the combined channel 46 to divide the flow. In this example, the combined flow is divided up and down with respect to the combined channel 46. This direction is not necessarily completely vertical, but may be partially vertical, for example, upward at an angle between upward and forward. Each combined flow in the divided channels 50 and 48 includes a strip or finger of the first material and a strip or finger of the second material. As mentioned above, this device is three-dimensional and can be formed from multiple layers.

The two separated combined flows are combined into a second combined flow through the combined channel 52, and the combined channel 52 is also used to converge the second combined flow. The second combined flow system in this example includes four interlaced fingers, two for each of the first and second materials. The second set of split channels 58, 54 then split the second combined stream into two separate combined streams. The structure 58 includes another bonding channel, forming a third bonding flow of 8 interlaced fingers, four for each of the first and second materials. Optionally, the structure 58 may also include an outlet opening with a chamfered wall, so that the combined flow is listed as a single flow from the series.

In operation, please refer to Figure 2 where the first material enters the series in the channel 40 as layer +1. The bonding layer serves as the reference layer 0. The second material then enters the tandem in the channel 42 as layer-1. The two materials are combined in layer 0 as a combined flow, in this example in Y structure 46. It should be noted that the combined flow includes two strips of material, one for each of the first and second material. The dividing channels 48, 50 then separate the combined flow into two separate combined flows, each flowing into layers +1 and -1. The layers are then combined into a second combined flow in the combined channel 52. Please note that the combined stream now has 4 material strips, 2 each for the first and second materials.

It should be noted that the structure in Figure 2 can suddenly change from layer to layer. This creates a void volume in the corners of many transitions, so that the material initially gathers in the corner and the rest of the flow will be passed through by the gathered material. However, with the passage of time and with the startup and shutdown of the device, the accumulated material will harden or plug the outlet orifice. In addition, these sudden transitions can cause irregularities in the flow, which can cause large amounts or complete mixing of materials in the strip. Therefore, it is desirable to make the flow have a "sweeping" phase, meaning that the angle is turned or processed, cut, or formed to eliminate sudden phases. This is discussed in the joint application "Micro-machining of oblique angles of flowable structures" (Attorney's Memorandum No. 20100587-US-NP-9841-0215).

In the desired fluid restriction, the process of dividing and joining can be continued to maintain the individual components without being completely mixed, and the fluid can also be in the form of a paste. At each stage of combining and converging, the line count doubles and the width of each line decreases by a factor of 2. The cumulative line width is reduced to 2ⁿ, Which is the same as the number of lines. From a manufacturing point of view, it is useful to combine devices from separately manufactured layers and then stack them with alignment tolerances. Then the layers are clamped together. Figure 3 shows an embodiment of this device.

In this embodiment, the device includes 9 layers. In this particular example, bolts pass through corresponding screw holes 63 on all layers to clamp the device together. The two materials enter from opposite sides of the device. However, this is only an example and is not meant or implied to limit any specific structure. Also, this example uses two materials and has three tandem repeats 25 times. All of them include examples used to help understand the present invention, and are not meant or implied to limit any specific structure.

The first material enters the device through the sealing plate 63 and enters the distribution manifold 61, while the second material enters the device through the facing sealing plate 59 and enters the distribution manifold 65. Each manifold generates a substantially equal source of fluid pressure for the array that performs the fluid folding series.

The optional layers 71 and 75 each include serial ports 60 and 70. The layers provide an entry point for each series in the device and help equalize the pressure of the material entering the series. These layers can also be referred to as layers-2 and +2 to correspond to the layer symbols used above.

On the first fluid folded layer 71, the array of ports 70 transports a first fluid from its distribution manifold to the array of separation channels 62 on the second fluid folded layer 81. The first fluid is deflected laterally along the first direction on the second fluid folded layer. On a third fluid folded layer 75, the array of ports 70 transports a second fluid from its distribution manifold to the array of separation channels 72 located on the fourth fluid folded layer 85. On the fourth fluid folded layer 85, the second fluid is deflected laterally in a second direction opposite to the first direction.

The direction of the separation channel can be elastic. For convenience, in this embodiment, all separation channels on a known layer are bent in the same direction. For example, looking at layer 81, the separation channels in arrays 62, 64, and 66 all divert the flow sideways to the right side of the figure. These channels can extend in different directions, or they can all extend to the left. The same applies to the separation channels on layer 85 in arrays 72, 74 and 76.

On the fifth fluid folded layer 95, the flows from the second and fourth layers are combined and converged into a common laminar flow by the bonding channels in the array 80. The flow is then "vertically" divided into two flows through the arrays 64, 74 on the second and fourth folded layers. The first combined flow is turned sideways in the first direction on the second folded layer of the use array 64. The second combined flow is turned sideways to enter an array of separation channels on the fourth folding layer of the use array 74.

Then, the flow returns to the fifth fluid folded layer 95, where the flows combine and converge into a second combined common laminar flow using an array. This process is repeated n times, each time the number of interdigitated strips of the material is doubled. Downstream of the final stage of segmentation and separation, the flows from all trains can optionally be combined together to a common trough-like outlet orifice. In this example, the process is repeated 3 times to produce 8 interdigitated strips from each tandem. There are 25 strings, so the resulting flow will have 200 interdigitated strips, 100 interdigitated strips for each material.

It should be noted that although the device shown here has the material arranged on the opposite side of the extrusion orifice, the material can be introduced on the same side of the orifice.

The co-extrusion device of FIG. 3 can be constructed and moved relative to a substrate to transport the material line, as shown as device 104 in FIG. 4. The substrate 102 is located at a distance of 10-1000 microns close to the applicator, which is called the working distance. The substrate moves relative to the device at a speed commensurate with the speed at which the fluid exits the print head/applicator 106. The co-extrusion device includes a fluid reservoir and print head/applicator 106, as well as control and power circuits. Alternatively, the fluid storage tank can be located remotely and the fluid can be delivered to the device through a hose or other piping system as needed.

In one embodiment, the print head assembly is composed of chamfered or generally cut 45-degree elements, so that the layered assembly can be kept close to the substrate at an oblique angle. The tilt of the print head assembly can cause a feature that the paste coming out of the fluid outlet will form an obtuse angle (between 90 degrees and 180 degrees) with the deposited paste on the substrate. This can reduce the bending on the extruded paste, help maintain the quality of the interdigital shape, reduce mixing, and increase the printing speed.

The co-extrusion device shown in Figures 2-4 can be used to form devices including batteries, fuel cells, electrical interconnections, and others, which benefit from interdigitated bands of dissimilar materials closely spaced apart. In the case of interconnection, the vertically stacked integrated circuits can be interconnected with a series of metal wires separated by insulating spacers along the edges. In the case of electrochemical devices such as fuel cells and batteries, interdigital structures can enhance performance in many ways. The air cathode of a metal-air battery can constitute an interdigitated region with hydrophilic and hydrophobic regions. This usually shows improved oxygen reduction activity and improves the power output of the device.

Figure 5 shows an example of this device 110. A hydrophobic film 114 has electrodes 112 fixed thereon. A separator 116 is fixed on the electrode 112. In this example, the electrode includes the intervening fingers of the porous hydrophobic region 118 and the porous hydrophilic electrocatalyst region 120. As described above, this can show improved oxygen reduction activity and improve power output. Moreover, this can also increase the surface area of the three-phase interface, where solid catalyst particles, liquid electrolyte and gaseous reactants interact with each other at the three-phase interface. For expensive catalysts such as platinum, this structure provides the potential to significantly reduce costs.

Figures 6-10 show examples of interdigital co-extruded structures particularly used in the formation of battery electrodes. In Figure 6, the electrode 130 includes two materials. The first material 132 is an electrode material, such as a cathode or an anode active electrode. The material 134 is an ion-conducting material that conducts electricity through a solid electrolyte or through porosity. Alternatively, the area of material 134 may be a fugitive accelerator or sacrificial material that is removed during the drying or firing phase in the latter part of the manufacturing process. In Figure 6, the thinner ion conduction region spans the entire thickness of the electrode layer.

In one embodiment of the formation process for this feature, the initial flow before folding may include two material flows, one is the material 134 and the other is the material 132. Or, there are three flows before folding, and one material 134 is surrounded by material 132. If the two materials interact with the wall of the flowable channel in different places, this wall will cause a lack of symmetry in the combination, mixing and separation of flows.

It should be noted that the deposition of the conductive cathode or anode material and the second material on the film will result in a structure with inter-digital features of different materials in the form of fluids. The term "fluid" as used herein means colloid, paste, slurry, or suspension. Although these cut-offs can be advanced through the drying or fire stage, they initially existed in fluid form.

In addition, at least one of the structures usually has a high aspect ratio. As used herein, the aspect ratio means the ratio of the maximum height to the maximum width of a structure or feature. Please refer to Figure 6, it can be seen that the material feature 134 in the interdigital structure has a high aspect ratio, and the height extending from the top to the bottom of the page is much larger than that from the left to the right of the page The width of the extension. Generally, at least one of the features formed from one of the interdigital structures has an aspect ratio greater than 1.

In another embodiment shown in Figure 7, the ion conduction region does not span the entire thickness of the electrode. This can be formed in two steps, first forming the overall coating of the cathode or anode material, and then forming the inter-digital coating of the ion conduction region and the electrode material. The single-stage method uses polymerization extrusion, in which the whole electrode material is introduced under the ion conduction region by cutting the time period of the introduced material to the printing head.

It should be noted that the ratio of materials varies greatly, and the cathode or anode material 132 has a much larger width than the ion conduction region 134. This can be produced in many different ways. For example, the input channels 42 and 40 shown in Figure 2 can have different sizes. Alternatively, the flow rate of the input channel material can be different, so that the material 132 entering one of the channels is far more than the material 134.

In Figure 8, the third material is introduced through the print head, in this example a primary conductive material 140, where the term "primary" refers to a higher expression of related characteristics than other materials. The manipulation of the material in the printing head and the subsequent folding process can be controlled to form these types of structures. For example, three materials can be combined in a three-way folding operation to form the central layer of the structure, and two-layer folding can be performed before the subsequent application of the central layer. This can be performed with three sequential applicators or unified in a single applicator that performs all three folds. In this embodiment, it is important to align the flowable layers so that the features in Figure 9 can be kept continuous by the structure being extruded.

Figure 9 shows a structure similar to Figure 7, in which the material 134 is an accelerator material, which is removed after printing to leave a gap such as 142. FIG. 10 shows an embodiment similar to FIG. 8 with the accelerator material removed to leave a gap 142 and a main conductive material 140 is provided. These gaps can then be filled with electrolyte material, such as a liquid electrolyte, to create a substantial ion conductive area in the electrode structure.

These gaps can then be filled with the opposite of the cathode or anode material and a spacer material, which prevents electrical contact between the cathode or anode material, but allows ions to be transported between the electrodes to form the opposite of an electrochemical cell Electrodes, such as batteries with alternating cathode or anode regions. Alternatively, these gaps can then be filled with the opposite of the cathode or anode material and a spacer material, and these gaps can then be filled with the second electrode material and the spacer material to form the opposite electrode of an electrolytic capacitor or supercapacitor.

Another embodiment mentioned above includes three materials that include flow. Refer to Figure 2 to see the possibility of changing the initial flow. It is also possible to use three or more input channels instead of having only two input channels 40 and 42 in the combined channel 46. This example is shown in the junction channel 146 in FIG. 11. In Figure 11, the bonding channel has 3 input channels to combine the three materials. From this point forward in the process, the rest of the structure is the same. However, in the rest of the structure, the flow of the three materials is folded instead of the flow of the two materials. More than three input channels can also be used; only one example of more than two materials is provided here.

In this way, interdigital structures with micron features on the micron scale can be made using a co-extrusion device. The co-extrusion device can take the form of a printing head to make the information of the printing technology structure faster.

<p>14~34. . . stage</p><p>10,12,A,B. . . Material</p><p>40,42. . . aisle</p><p>44. . . Binding channel</p><p>46. . . Binding channel</p><p>50,48. . . Split channel</p><p>52. . . Binding channel</p><p>58,54. . . Second split channel</p><p>63. . . Screw hole</p><p>63,61. . . sealing board</p><p>61,65. . . Distribution manifold</p><p>71. . . First fluid fold</p><p>81. . . Second fluid fold</p><p>62,72. . . Separation channel</p><p>75. . . Third fluid fold</p><p>85. . . Fourth fluid folded layer</p><p>62,64,66. . . Array</p><p>72,74,76. . . Array</p><p>95. . . Fifth fluid folded layer</p><p>104. . . Device</p><p>102. . . Substrate</p><p>106. . . Print head/applicator</p><p>110. . . Device</p><p>114. . . Hydrophobic film</p><p>112. . . electrode</p><p>116. . . Divider</p><p>118. . . Porous hydrophobic area</p><p>120. . . Porous hydrophilic electrocatalyst area</p><p>130. . . electrode</p><p>132. . . First material</p><p>134. . . Material</p><p>140. . . Conductive materials</p><p>142. . . gap</p><p>146. . . Binding channel</p>

Figure 1 is a block diagram showing the fluid flow of two materials into a finger-like cross monomer flow.

Figure 2 is an isometric view showing an embodiment of the fluid path.

Figure 3 is an exploded view showing an embodiment of a fluid co-extrusion device.

Figure 4 shows an embodiment of a co-extrusion device and a substrate.

Figure 5 shows an embodiment of a metal-air battery with a finger-shaped cross structure.

Figures 6-10 show cross-finger co-extrusion examples.

Figure 11 shows an example of combining a channel of one of three materials.