Systems and methods for electrode fabrication

Abstract

The present disclosure provides systems and methods for electrode fabrication. Methods and systems are provided for manufacturing electrodes by binder jetting. In one example, a method may include coating a current collector with a powder including particles of an electroactive material, and applying a binder by spraying an ink including the binder in a controlled pattern onto the powder-coated current collector. The ink is ejected to form an electrode having patterned regions of bonded powder and patterned regions of unbonded powder, wherein the unbonded powder is fixed between the regions of bonded powder.

Description

Technical Field

[0001] The present description generally relates to methods and systems for making electrodes for batteries. Background Art

[0002] The large-scale manufacture of electrodes generally includes preparing a slurry comprising at least electrode active material particles and a binder in a solvent. The slurry can be applied as a layer to a current collector by a large-scale manufacturing process (such as slot die coating), followed by a drying step in which the solvent is removed, leaving the electrode active material particles held in place by the binder. Although the binder can be evenly dispersed when wet, when dry, the binder may become denser in certain areas of the electrode, thereby causing some areas of the electrode to have weak adhesion / film cohesion. In addition, the binder may not be conductive and hinder electrons and / or ions from flowing through the electrode. For these reasons, it may be desirable to minimize the amount of the binder in the electrode by controlled application of the binder. Summary of the invention

[0003] Attempts to reduce electrode manufacturing time by reducing drying time include applying a binder directly to the electrode active material particles in the absence of a solvent. However, the inventors herein have recognized potential problems with such methods. As an example, applying a binder / solvent mixture directly to the electrode active material particles without forming a slurry may result in an uneven electrode, in which the density of the electrode active material particles varies spatially in an uncontrolled manner across the electrode. This unevenness may result in areas of poor conductivity and cause degradation of the battery. In addition, applying a binder in this manner may also result in applying an excessive amount of insulating binder to the electrode, thereby reducing the conductivity of the electrode.

[0004] In one example, the above problem can be solved by a method comprising: coating a powder onto a first current collector, wherein the powder comprises particles of an electroactive material; spraying an ink comprising a binder onto the first current collector coated with the powder in a controlled pattern; and forming an electrode comprising a patterned area of ​​bonded powder and a patterned area of ​​unbonded powder, wherein the unbonded powder is fixed between the patterned areas of the bonded powder. In this way, the binder is applied to the electrode active material bed in a layer-by-layer manner in a controlled and reproducible pattern that uses minimal solvent and reduces electrode manufacturing time. Controlling the binder application in this manner provides flexibility in customizing the electrode structure to optimize battery performance as needed for different applications.

[0005] As an example, the density of the electrode active material particles on the electrode can be adjusted to account for electrode swelling during multiple charge and discharge cycles. In addition, the binder ink can also incorporate other electrode additives, such as dopants or thermally activated catalysts, which can be conductive to further reduce the internal resistance of the battery. In this way, the structure and composition of the electrode can be controlled on a micrometer scale with minimal use of solvents.

[0006] It should be understood that the above summary is provided to introduce a series of concepts further described in the detailed description in a simplified form. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to embodiments that address any disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 An example of a process flow diagram for manufacturing a battery array is shown.

[0008] Figure 2 A first example of electrode fabrication using a binder jetting system is shown.

[0009] Figure 3 A second example of electrode fabrication using a binder jetting system is shown.

[0010] Figure 4 A flow chart illustrating an example of a method for manufacturing an electrode using a binder jetting system.

[0011] Figure 5A A graphical representation of adhesive deposition resulting from dispensing adhesive using an adhesive jetting system is shown.

[0012] Figure 5B It shows that Figure 5A Illustration of bound electroactive material particles after binder deposition is shown.

[0013] Fig. 6A An example of a first pattern printed by a binder jetting system is shown.

[0014] Figure 6B Shows Fig. 6A An enlarged view of the first pattern.

[0015] Figure 6C A three-dimensional illustration of a first pattern printed by a binder jetting system is shown.

[0016] Figure 7 A graphic representation of areas of high ink density and areas of low ink density is shown.

[0017] Figure 8 An example of a second pattern printed by a binder jetting system is shown.

[0018] Fig. 9 Shows Figure 8 Illustration of a second pattern of bonded and unbonded electroactive material particles. DETAILED DESCRIPTION

[0019] The following description relates to systems and methods for manufacturing electrodes for assembly into battery cells. Multiple battery cells may be packaged together to form a battery array, which may be used in a wide variety of applications, including providing an energy source for a vehicle. Figure 1 A process flow chart for manufacturing a battery array from electrode raw materials is shown in . One of the steps in the process flow chart is electrode manufacturing. By applying an ink including a binder to electroactive material particles using a binder jetting system, the process time associated with electrode manufacturing can be reduced. In this article, the electroactive material particles can be particles that participate in the electrochemical reaction of the battery. For example, the electroactive material particles can include anode electroactive material particles or cathode electroactive material particles. The binder jetting system can be applicable to a binder jetting printer used in additive manufacturing. In short, the inkjet head can be connected to a precision servo motor to accurately control the movement of the inkjet head in an xy plane parallel to the substrate. The binder jetting system includes a controller configured to provide instructions for positioning the inkjet print head and for dispensing ink from the inkjet head with precise droplet shapes and saturation levels. In this way, a precise two-dimensional pattern of ink is distributed. Repeat the process for multiple layers of powder to form a three-dimensional structure. Figure 2 and Figure 3 Two examples of electrode manufacturing processes using a binder jetting system are shown in FIG. Figure 4 An example of a method for electrode fabrication and pre-assembly using binder jetting is shown in .

[0020] The electrode structure including patterned regions to which the electroactive material particles are bonded and patterned regions to which the electroactive material particles are not bonded can be purposefully adjusted by patterning the binder onto the electrode active material particles using a binder jetting system. FIG. 5A to FIG. 5B An example of how a binder may be deposited onto a bed of electroactive material particles is shown in . FIG. 6A to FIG. 6C An illustration of a possible pattern is shown in In addition to controlling the pattern of bound electroactive material particles, a binder jetting system can also controllably print areas of high ink density and areas of low ink density. Figure 7 A diagram showing an example of high ink density and low ink density is shown in FIG. FIG. 6A to FIG. 6C and Figure 7The pattern and varying density distribution of the binder shown can provide a lattice of bound and unbound electroactive material particles. Figure 8 A photograph of an example of a lattice formed by spraying a binder in a layer-by-layer manner is shown in FIG. Figure 8 An exemplary lattice of can include both bonded particles and unbonded particles. Fig. 9 It is shown in Figure 8 Illustration of bonded and unbonded particles of an example.

[0021] Now turn to Figure 1 , a process flow chart 100 for manufacturing a battery array is shown. The electrode component 102 may include electrode active material particles. The electrode active material particles may be cathode active material particles or anode active material particles. In one example, the electrode active material particles may have a D50 of <20 μm. In an alternative example, the electrode active material particles may have a D50 of <15 μm. In another example, the electrode active material particles may have a D50 of <5 μm. In an exemplary embodiment, the electrode active material particles may be an electrode active material of a lithium ion battery configured to intercalate and deintercalate lithium ions.

[0022] The electrode component 102 may also include a current collector. The current collector may be a conductive metal (such as aluminum or copper) sheet on which electrode active material particles are coated. The electrode component 102 may also include a binder and a solvent. The binder may be configured to fixedly couple the electrode active material particles to each other and to the current collector. The binder may be a polymer material dissolved in a solvent carrier for manufacture. The electrode component 102 may also include additional additives for enhancing battery performance, including but not limited to conductivity enhancing dopants or supplementary lithium sources.

[0023] Electrode manufacturing process 104 can produce electrode 106 from electrode component 102. Electrode 106 can include electroactive material particles and a binder applied to a current collector. Electrode manufacturing process 104 can include pressing a powdered material including electroactive material powder onto the current collector, and spraying a binder dissolved in a solvent carrier onto the powdered material. In addition, electrode manufacturing process 104 can include slitting the coated current collector. This can be described below with respect to Figures 2 to 4 The electrode manufacturing process 104 is described in further detail.

[0024] The electrode 106 may be further subjected to a pre-assembly manufacturing process 108 and a cell assembly process 110 to form a battery cell 112. The pre-assembly manufacturing process 108 may include drying and slotting the electrode. In this article, drying refers to removing the solvent from the electrode. In some examples, the pre-assembly manufacturing process 108 may also include curing, wherein the binder is further cross-linked. The drying process is different from the curing process. Because the electrode manufacturing process 104 uses a binder jet, the drying step of the pre-assembly manufacturing process may be faster than when using a high solvent electrode manufacturing process (such as slurry coating and calendaring). Slotting the electrode can form one or more tabs of the electrode 106.

[0025] The cell assembly 110 may include stacking or laminating a plurality of electrodes, such as the electrode 106, and inserting the plurality of electrodes into a bag. In addition, the cell assembly 110 may include filling with electrolyte, forming, and aging. The battery cell 112 may then be subjected to an electrochemical test 114. The electrochemical test 114 may be followed by an array assembly 116 to form a battery array 118. The array assembly 116 may include stacking and compressing a plurality of battery cells, such as the battery cell 112, into a housing, and electrically connecting the plurality of battery cells via bus bars.

[0026] like Figure 1 As shown, the process for manufacturing a battery array may include many steps. Reducing the processing time of any step can help improve the efficiency of the process. When the electrode manufacturing process uses a solvent-based slurry to uniformly coat the collector with electrode active material particles and a binder, a large, energy-intensive furnace may be required to remove the solvent. In addition, the solvent may be toxic and an expensive solvent recovery system may be required. By eliminating the slurry and instead spraying the binder solution onto the electroactive material powder, the amount of solvent and binder used in the electrode manufacturing process can be reduced, thereby reducing the equipment time required for drying. In addition, minimizing the amount of binder included in the electrode can increase the conductivity of the electrode and reduce the total amount of material included in the electrode. In addition, by using a jet to apply the binder, a pattern (e.g., a lattice) of bonded electroactive material particles can be formed in a layer-by-layer manner. The layers and patterns can be adjusted to take into account the swelling of the electrode, thereby increasing the usable life of the battery cell and the battery array including the battery cell.

[0027] Now turn to Figure 2 , shows a diagram of a first embodiment of an electrode manufacturing system 200 using a binder jetting system. An axis system 201 is provided for Figure 2 and Figure 3 The z-axis may be parallel to the direction of gravity. The x-axis may correspond to the lateral direction, and the y-axis may correspond to the longitudinal direction. The electrode manufacturing system 200 may be similar to Figure 1The electrode manufacturing process 104 of the embodiment of the present invention can be a step in manufacturing a battery array. The electrode manufacturing system 200 can be a roll-to-roll process and can include a roller 202 that can rotate in a direction that advances the current collector 204 in a forward longitudinal direction indicated by arrow 206.

[0028] The current collector 204 can be a conductive metal foil, such as aluminum or copper described above with respect to the electrode component 102. Moving in the forward longitudinal direction, the current collector 204 can first pass under the powder dispensing unit 208. The powder dispensing unit 208 can include a powdered electrode component, which includes particles of an electroactive material and other optional powdered electrode components, such as conductivity enhancing additives, thermally activated catalysts and / or additional lithium sources. In this way, the additional electrode components can be evenly distributed throughout the electrode. The powder dispensing unit 208 can form a loose powder layer 210 in coplanar contact with the current collector 204. The density of the loose powder layer 210 can be controlled by controlling the speed of the roller and the dispensing rate of the powder dispensing unit 208.

[0029] The current collector 204 including the loose powder layer 210 may be advanced in a forward longitudinal direction by the roller 202 and passed under the powder leveling / compacting unit 212. The powder leveling / compacting unit 212 may compress the loose powder layer 210 to form a dense powder layer 214. The powder leveling / compacting unit 212 may additionally level the loose powder layer 210, thereby leveling the dense powder layer 214 in the xy plane. The density of the dense powder layer 214 may be controlled by controlling the force applied by the powder leveling / compacting unit 212.

[0030] The current collector 204 including the dense powder layer 214 can be advanced in the forward longitudinal direction by the roller 202 and passed under the binder jetting system 216. The binder jetting system 216 can include an inkjet printhead 218 and an ink recirculation system 220. The ink can be a solution of a binder (e.g., a polymer) in a suitable solvent. In some examples, the ink can additionally include a conductivity enhancing dopant, a thermally activated catalyst, and / or an additional lithium source. In this way, additional electrode components can be selectively placed within the electroactive particles of the binding volume. The amount of binder per volume in the solvent can be maximized to allow a minimum amount of solvent while maintaining a sufficiently low viscosity to dispense the solution through the inkjet printhead 218. The ink recirculation system 220 can be fluidly coupled to the inkjet printhead 218 so that the ink recirculation system 220 can be configured to circulate the solution to the inkjet printhead 218 along arrow 224, and circulate the solution from the inkjet printhead 218 back to the ink recirculation system 220 along arrow 226. Circulating the ink in this manner may help prevent the formation of deposits and clogging of the inkjet printhead 218 .

[0031] The inkjet print head 218 can be configured to move in a lateral direction along the x-axis and dispense ink onto the dense powder layer 214, thereby forming a bonded powder layer 222. The bonded powder layer 222 and the current collector 204 can together form an electrode, such as Figure 1 The inkjet print head 218 can be communicatively coupled to a control system 228. The control system 228 can include a human-machine interface, such as a keyboard and / or a mouse. The control system 228 can also include a non-volatile memory. The non-volatile memory can store instructions for activating a motor to move the inkjet print head 218 in the x-direction and dispensing ink at a desired location when the inkjet print head 218 moves in the x-direction. In this way, a controlled pattern of adhesive can be delivered to a desired location as the current collector advances in a forward longitudinal direction to form a pattern in the xy plane of the current collector 204.

[0032] The current collector 204 including the bonding powder layer 222 can pass under the powder dispensing unit to form a subsequent loose powder layer in coplanar contact with the bonding powder layer 222. In some examples, the current collector 204 can be fed to a separate set of rollers and different powder dispensing units. In an alternative example, the current collector 204 can return to the powder dispensing unit 208. In another example, the roll-to-roll system may include a plurality of powder dispensing units, each of which includes a different powder composition. A loose powder layer can be formed by dispensing powder from one or more of the plurality of powder dispensing units. In this way, multiple layers of powder and binder can be configured to form a three-dimensional pattern, which can be adjusted according to the desired particle density. In some examples, the three-dimensional pattern can include two to five layers. In some examples, the three-dimensional pattern can be a periodic engineered structure configured to guide current through the electrode, keep the electroactive material particles in place, and provide strength to the electrode structure when included in the battery cell. By including a minimum amount of solvent in the ink, the electrode drying time before starting the pre-assembly manufacturing process can be reduced.

[0033] Now turn to Figure 3 , a second embodiment of an electrode manufacturing system 300 using a binder jetting system is shown. The second embodiment of the electrode manufacturing system 300 may include some of the same features as the first embodiment of the electrode manufacturing system 200. Such features are similar to Figure 2 The tags in are the same and may not be reintroduced.

[0034] A second embodiment of the electrode manufacturing system 300 may include a build box 302. The build box 302 may include a build platform 304 and a platform support 306. The build platform 304 may be configured to move forward and backward longitudinally along the y-axis. The build platform support 306 may be configured to move the build platform 304 up and down along the z-axis. In this manner, the build platform 304 may advance the current collector 204 through the powder dispensing unit 208, the powder leveling and compacting unit 212, and the binder jetting system 216 to form a first electrode layer 308 on the first side 204a of the current collector 204. The build platform 304 may advance the current collector 204 multiple times. In this manner, the first electrode layer 308 may include multiple dispensed powder layers to form as described above with respect to Figure 2 The three-dimensional pattern of bonded and unbonded powders described. In some examples, the current collector 204 can be notched and slotted prior to using the electrode manufacturing system 300. Notching and slotting the current collector 204 prior to electrode manufacturing can reduce the cutting of the already deposited electroactive material particle layer, thereby reducing the generation of fine particle dust and the accompanying process control required to control the fine particle dust. In addition, the discarding and subsequent waste of electroactive material bonded to the portion of the current collector removed during notching and slotting can be reduced.

[0035] Current collector 204 including first electrode layer 308 can be removed from build box 302 and rotated 180 degrees about the y-axis or x-axis and then placed back onto build platform 304 of build box 302 or into a different build box configured similarly to build box 302. In this manner, the face of the first electrode layer opposite current collector 204 is in coplanar contact with the build plate. In some examples, first electrode layer 308 can be partially cured prior to being rotated and placed on the build plate.

[0036] Then, a loose powder layer 210, a dense powder layer 214, and a bonding powder layer 222 can be formed by passing the second side 204b of the current collector 204 again in the forward direction through the powder dispensing unit 208, the powder leveling and compacting unit 212, and the binder injection system 216. The second side 204b is opposite to the first side 204a on the z-axis. The loose powder layer 210 can be deposited by dispensing powder on the current collector 204 by the powder dispensing unit 208. The loose powder layer 210 can be compacted into a dense powder layer 214 by the powder leveling and compacting unit 212. The area of ​​the dense powder layer can be bonded with a binder dispensed from the binder injection system 216 into the bonding powder layer 222. A plurality of bonding layers can be formed on the second side 204b to form a second electrode layer including a three-dimensional pattern of bonded particles and unbonded particles, as described above with respect to the first electrode layer 208.

[0037] In this way, a multilayer electrode can be formed, including a first electrode layer bonded to a first side of the current collector and a second electrode layer bonded to a second side of the current collector, the second side being opposite to the first side. In some examples, the powder included in the powder dispensing unit 208 may be different when forming the loose powder layer 210 for the second electrode layer and when dispersing the powder and forming the first electrode layer 308. In this way, a multilayer electrode having a first electrode layer and a second electrode layer can be formed, and the composition of the first electrode layer can be different from the composition of the second layer. For example, the first electrode layer may include particles of an electroactive material in a first particle size distribution, and the second electrode layer may include particles of an electroactive material in a second particle size distribution. As an alternative example, the first electrode layer may include particles of a cathode electroactive material, and the second electrode layer may include particles of an anode electroactive material, and the multilayer electrode may be included in a bipolar battery cell.

[0038] Now turn to Figure 4 , showing the electrode manufacturing and pre-assembly process (e.g., Figure 1 An example of a method 400 of an electrode manufacturing process 104 and a preassembly process 108) using jetting to distribute a binder to a dense powder layer. Instructions for performing method 400 may be at least partially executed by a controller based on instructions stored on a memory of the controller and in conjunction with signals received from sensors of the manufacturing system. The controller may employ an actuator of a manufacturing system, which may include a binder jetting assembly, to manufacture an electrode according to the method described below. In one example, the manufacturing system may be as described above with respect to Figure 2 In an alternative example, the manufacturing system may include the roll-to-roll manufacturing system described above. Figure 3 Build box as described.

[0039] At 402, method 400 includes coating the current collector with a powder. Coating the current collector with a powder may include coating the current collector with a powder dispensing unit such as Figures 2 to 3 The powder is dispensed onto the current collector using a powder dispensing unit 208 of the type described herein. The powder includes particles of an electroactive material and may additionally include additives such as conductive additives or thermally activated catalysts. Additionally, coating the current collector with the powder may include using a powder leveling and compacting unit such as Figures 2 to 3 The powder leveling and compacting unit 212 of the present invention compacts and flattens the powder onto the current collector. Coating the current collector with powder can produce a densely packed powder layer on top of the current collector. In some examples, where the manufacturing system includes a build box, the current collector coated with powder can be a current collector that is grooved and notched before the method 400 begins.

[0040] At 404, method 400 includes spraying a binder onto the coated current collector to form an electrode. The sprayed binder may be sprayed by a binder spraying system such as Figures 2 to 3 The binder jetting system 216 is performed. The binder jetting system can be configured to introduce an ink consisting of a binder and a solvent into the densely packed powder layer. The ink can be jetted in a desired amount at a desired location based on instructions from a controller of the binder jetting system. The jetted ink can bond an area of ​​the dense powder layer to itself and the current collector to form a bonded powder layer. In some examples, the ink may also include additives, such as conductivity enhancing additives or heat-activated catalysts. The assembly of the bonded powder layer fixedly connected to the current collector and in coplanar contact with the current collector may be referred to as an electrode.

[0041] At 405, method 400 determines whether additional layers are needed. If additional layers are needed (yes), method 400 returns to 402, and the bonding powder layer formed at 404 is recoated with powder, and then leveled and compacted to form a densely packed powder layer. Then a binder is sprayed onto the densely packed powder layer to add a second bonding powder layer to the electrode. The second layer can be in coplanar contact with the first layer and fixedly connected to the first layer. The position and amount of the sprayed binder can be different at the second layer and on the first layer. Steps 402 and 404 can be repeated many times. Each time, a binder can be sprayed according to an instruction generated by a controller of the binder spraying system. In this way, a three-dimensional pattern of bonding particles, such as a lattice or a spiral tetrahedron, can be formed in a layer-by-layer manner.

[0042] If method 400 determines that no additional layer is needed (no), method 400 continues to step 406 and may include drying and curing the electrode. Drying the electrode may include removing solvent from the ink mixture, and curing may include hardening of the binder polymer. Both drying and curing may be performed by directing some form of energy to the electrode. The amount of solvent used in the ink sprayed onto the dense powder layer at 404 may be minimized to reduce the amount of time required for step 406. The same energy source may be used for drying and curing, thereby performing drying and curing simultaneously. Due to the relatively small amount of solvent, drying may be completed before curing is completed, and curing may be a time-limiting factor for step 406. In one example, drying and curing the electrode may include drying and curing using radiant heat energy in a furnace. In an alternative example, drying and curing the electrode may include using energy delivered by photons. The photons may be coherent (e.g., laser) or incoherent. As a non-limiting example, the photons may be ultraviolet photons and / or infrared photons. In another example, drying and curing may include using energy from electrons using an electron beam.

[0043] At 412, method 400 determines whether an additional electrode layer is required. If an additional electrode layer is required (yes), method 400 returns to 402, and the second uncoated side of the current collector is coated as described above with respect to steps 402 to 410, and a second electrode layer is formed on the current collector. In some examples, the powder coating of the uncoated current collector to form the second electrode layer may include particles different from the particles of the powder coating of the first electrode layer (such as different electroactive particles or different additives). If an additional electrode layer is not required (no), method 400 optionally proceeds to steps 408 and 410 or directly to step 418.

[0044] In some examples, when the current collector is not slit or grooved prior to coating with powder, the method 400 proceeds to slit the electrode at step 408 and then groove the electrode at step 410. Slitting the electrode may include cutting the edge of the current collector to the size required for the battery cell housing. A binder may be sprayed onto the current collector so that no binder is present on the portion of the dense powder layer that is trimmed by slitting the electrode. In the absence of a binder, the dense powder layer can be easily removed from the current collector section that was trimmed during slitting. In this way, the powder including the particles of the electroactive material can be recovered by reintroducing the powder into the powder dispensing unit.

[0045] At 410, method 400 includes slotting the electrode. Slotting the electrode may include cutting the current collector to form tabs. At step 404, a binder may be sprayed onto the current collector such that no binder is present on a portion of the current collector removed by slotting. In the absence of a binder, a dense powder layer may be easily removed from the portion of the current collector removed by slotting. In this manner, a powder including particles of electroactive material may be recovered.

[0046] At 418, method 400 includes assembling the battery cell. The process of assembling the battery cell may be performed using the method described above with respect to Figure 1 The resulting electrodes are then used in the next step of manufacturing a battery array. The method 400 ends.

[0047] Now turn to Figure 5A , which shows an inkjet nozzle 502 directing ink (e.g., including a binder and a solvent) droplets 504 toward a densely packed powder layer 506. The inkjet nozzle 502 can be part of an inkjet printhead (such as inkjet printhead 218), and the densely packed powder layer can be similar to the dense powder layer 214. The densely packed powder layer 506 can include voids 508 between particles of the densely packed powder layer. Figure 5BA section 510 of a densely packed powder layer 506 is shown after a droplet of ink reaches the densely packed powder layer 506. Voids 508 may be at least partially filled with ink 512. Ink 512 may originate from ink liquid 504. After drying, the solvent may be removed from the ink, leaving the binder and any other additives included in the ink. After curing, the binder may fixedly couple the particles of the densely packed particle layer to each other and to the current collector. By selectively and repeatedly distributing ink on the surface of the densely packed particle layer in a layer-by-layer manner as described above with respect to method 400, a three-dimensional pattern of bonded particles, such as a lattice or a spiral tetrahedron, may be formed.

[0048] Relative to Figures 2 to 3 The manufacturing direction shown in FIG. 1 is viewed downward along the z-axis, and an example of a binder layer that can be ejected by an inkjet print head onto a densely packed particle layer is shown in FIG. FIG. 6A to FIG. 6B Shown at different magnifications in Figure 6C 3D representation is shown in FIG. Fig. 6A An example of an ink layer 600 deposited by an inkjet printhead is shown. The layer 600 may include bonded areas 602 and unbonded areas 604. The dots on the layer 600 may represent bonded areas 602 where ink is deposited, and the white areas may represent unbonded areas 604. Figure 6B Look more closely at section 601 of layer 600. Bonded areas 602 and unbonded areas 604 can be shaped into a layer forming a desired three-dimensional pattern of bonded areas. The size and placement of the bonded areas can be adjusted by instructions stored on the controller of the binder jetting system to determine the slices of the desired three-dimensional pattern. Figure 6C An example of a three-dimensional pattern 650 is shown in FIG. The three-dimensional pattern 650 can be an example of a multilayer electrode that includes a current collector 652 and a first pattern 654 positioned on a first side 662 of the current collector and a second pattern 656 positioned on a second side of the current collector opposite the first side 662 on the z-axis. The first pattern 654 and the second pattern 656 can both include a bonding volume 658. The bonding volume 658 can be composed of multiple bonding regions (such as FIG. 6A to FIG. 6B In addition, there may be an unbonded volume 660 between the bonded volumes 658. Both the bonded volume 658 and the unbonded volume 660 may include electroactive material particles. The electroactive material particles in the bonded volume 658 may be fixedly connected to each other by a binder, while the electroactive material particles in the unbonded volume 660 may be fixed between the bonded volumes 658 by close packing without a binder.

[0049] The bonding area 602 may also include areas where the ink is dispersed (e.g., pixels) and areas where the ink is not dispersed, as described below with respect to Figure 7further described. Now turn to Figure 7 , an example of a lightly inked area 702 and a heavily inked area 704 is shown. The lightly inked area 702 may include an inked portion (shown as a black pixel) and an uninked portion (shown as a white pixel). The heavily inked area 704 may not include an uninked portion. In other words, a portion of the pixels of the lightly inked area 702 include ink, and each pixel of the heavily inked area 704 includes ink. By adjusting the number of inked or uninked areas within the inked portion, the amount of solvent and binder used in manufacturing the electrode can be minimized while still providing sufficient adhesion of the electroactive material particles to each other and to the current collector. The three-dimensional pattern of the bonding volume (such as the first pattern 654 and the second pattern 656) may include both heavily inked portions and lightly inked portions. For example, portions of the three-dimensional pattern that are under higher mechanical stress during battery cell manufacturing and battery array assembly may be heavily inked portions, while those portions under lower mechanical stress may be lightly inked portions.

[0050] Now turn to Figure 8 , shows an alternative example of a three-dimensional pattern 800 formed by spraying a binder at densely packed powder layers in a layer-by-layer manner. An axis 801 is shown for Figure 8 Photos and Fig. 9 The z-axis may correspond to the vertical direction and (eg, via Figure 2 or Figure 3 The manufacturing process shown in ( ) constructs the direction of the three-dimensional pattern 800, and as a test, the three-dimensional pattern 800 is formed using particles on a substrate 803. As an example, the ratio of the binder to the solvent in the ink sprayed at the particles can be between 10 wt % and 20 wt %. In addition, after drying and curing, the binder can account for less than or equal to 3 wt % of the electrode.

[0051] The three-dimensional pattern 800 can be formed by multiple powder and ink layers, each of which includes bonded areas and unbonded areas configured to form the three-dimensional pattern 800. The three-dimensional pattern can include bonded volumes 802 and unbonded volumes 804 in alternating layers along the x-axis. The bonded volumes 802 can include a binder and steel particles, and the unbonded volumes 804 can include steel particles without a binder. The steel particles without a binder can be fixed to the substrate by being wedged between the bonded volumes 802.

[0052] The particles of three-dimensional pattern 800 may be replaced with particles of electroactive material to make three-dimensional pattern 800 suitable for a battery electrode. Fig. 99 shows a two-dimensional slice 900 of a three-dimensional pattern including electroactive material particles and a binder, such as three-dimensional pattern 800. The bonding region 902 may include electroactive material particles and a binder, thereby bonding the electroactive material particles to each other, such as Figure 5B As shown. Unbound electroactive material particles 904 can be wedged between bonding regions 902. Due to the insulating properties of the binder, ions (e.g., lithium ions) diffusing through the electrode during charging and discharging of the battery cell can preferentially follow the path shown by arrows 906 through unbound electroactive material particles 904. In this way, the path of ions through the electrode can be guided by the three-dimensional pattern of the bonding volume. Guiding the ion path in this way can help achieve fast charging and discharging of the battery.

[0053] The distance between the bonding volumes can vary across the volume of the three-dimensional pattern. As shown in the two-dimensional slice 900, the bonding area 902 can be separated by a first distance 908 at the first end 910 of the two-dimensional slice 900. The bonding area 902 can be angled so that the bonding area 902 is separated by a second distance 912 at the second end 914 of the two-dimensional slice 900. The first end 910 can be opposite to the second end 914 along the x-axis. The electroactive material particles closer to the first end 910 can be less densely packed than the electroactive material particles closer to the second end 914. In some examples, the density of the unbonded electroactive material particles can vary between 20% and 70% based on the three-dimensional pattern of the bonding volume. In this way, the three-dimensional pattern of the bonding volume can be used to adjust the density of the electroactive material particles fixed between the bonding volumes. The density of the unbonded electroactive material particles can be adjusted to take into account the swelling of the electrodes during multiple charging and discharging cycles of the battery cell. As an example, the bonding volumes can be spaced far apart to reduce the density of electroactive material particles in portions of the electrode that are susceptible to swelling, and can be spaced closely together to increase the density of electroactive material particles in portions of the electrode that are less susceptible to swelling. In this way, swelling of the electrode can be mitigated while still maintaining the desired power density of the battery cell.

[0054] The technical effect of using binder jetting to apply a binder during electrode manufacturing is to reduce the amount of solvent used in the process and enable a controlled formation of a three-dimensional pattern of bonded electroactive material particles. Reducing the amount of solvent can reduce the drying time required for electrode manufacturing, thereby improving the efficiency of the electrode manufacturing process. In addition, the use of a binder jetting system can reduce the amount of binder required, which can help improve the conductivity of the electrode. In addition, the binder jetting system can enable the formation of a three-dimensional pattern of bonded electroactive material particles and unbonded electroactive material particles, and the layer-by-layer process can allow the properties within the electrode to be adjusted layer by layer, which is not available in a slurry-based method. The three-dimensional pattern can be configured to guide lithium diffusion through the electrode in a desired direction. In addition, a three-dimensional pattern can be formed to adjust the density of unbonded electroactive material particles to compensate for the swelling of the electroactive material. In addition, the binder jetting system can enable additional materials (e.g., catalysts or conductive additives) to be selectively added to the electrode in the powder layer or in the inking layer.

[0055] Figures 2 to 3 , FIG. 5A to FIG. 6C as well as Figures 8 to 9 An exemplary configuration with relative positioning of various components is shown. Unless otherwise specified, in at least one example, if shown as directly contacting or directly connected to each other, such elements may be referred to as directly contacting or directly connected, respectively. Similarly, in at least one example, elements shown as being adjacent or adjacent to each other may be adjacent or adjacent to each other, respectively. As an example, components that are coplanarly contacted with each other may be referred to as coplanar contact. As another example, in at least one example, elements that are positioned apart from each other with only space therebetween and no other components may be referred to as such. As another example, elements that are shown as being above / below each other, on opposite sides or on the left / right side of each other may be referred to as such relative to each other. In addition, as shown in the accompanying drawings, in at least one example, the topmost element or the vertex of the element may be referred to as the "top" of the component, and the bottommost element or the bottommost point of the element may be referred to as the "bottom" of the component. As used herein, top / bottom, upper / lower, above / below may be relative to the vertical axis of the accompanying drawings, and are used to describe the positioning of the elements of the accompanying drawings relative to each other. Thus, in one example, an element shown as being above other elements is located directly above the other elements. As another example, the shapes of the elements depicted in the drawings may be referred to as having these shapes (e.g., such as being circular, linear, planar, curved, rounded, chamfered, angled, etc.). In addition, in at least one example, elements shown as intersecting each other may be referred to as intersecting elements or intersecting each other. Further, in one example, an element shown as being within another element or being shown as being outside another element may be referred to as such.

[0056] According to the present invention, a method includes: coating a powder onto a first side of a current collector, wherein the powder includes particles of an electroactive material; spraying an ink including a binder onto the first current collector coated with the powder in a controlled pattern; and forming an electrode including patterned areas of bonded powder and patterned areas of unbonded powder, wherein the unbonded powder is fixed between the patterned areas of the bonded powder.

[0057] In one aspect of the invention, the method comprises coating a second side of the current collector with a powder, the second side being opposite to the first side.

[0058] In one aspect of the invention, coating powder onto the first side of the current collector comprises coating with a first powder, and coating powder onto the second side of the current collector comprises coating with a second powder, wherein the composition of the first powder is different from the composition of the second powder.

[0059] In one aspect of the invention, the first powder comprises a cathode electroactive material and the second powder comprises an anode electroactive material.

[0060] In one aspect of the invention, the method includes slitting and grooved the current collector prior to applying powder onto the first side of the current collector.

[0061] In one aspect of the invention, the ink further comprises one or more of a conductivity enhancing dopant or a thermally activated catalyst.

[0062] In one aspect of the invention, the method is performed using a roll-to-roll process or using a build box.

[0063] According to the present invention, an electrode for a battery cell is provided, comprising: a current collector; a three-dimensional pattern comprising a volume of bonded electroactive material particles fixedly connected to the current collector; and unbonded electroactive material particles fixed between the volume of bonded electroactive material particles.

[0064] According to an embodiment, the volume of bound electroactive material particles is configured to determine a path for ions through the electrode.

[0065] According to an embodiment, the distance between said volume of bound electroactive material particles determines the density of said unbound electroactive material particles fixed between said volume of bound electroactive material particles.

[0066] According to an embodiment, the density of the unbound electroactive material particles is configured to allow swelling of the unbound electroactive material particles.

[0067] According to an embodiment, the volume of bound electro-active material particles includes a conductivity enhancing dopant.

[0068] According to an embodiment, the electrode is a multilayer electrode including the three-dimensional pattern, the multilayer electrode being fixedly coupled to a first side of the current collector and fixedly coupled to a second side of the current collector, the first side being opposite to the second side.

[0069] According to an embodiment, the three-dimensional pattern is a periodic engineered structure configured to retain unbound particles, provide strength to a battery cell including the electrode, and direct current flow through the electrode.

[0070] According to the present invention, a method includes: forming a densely packed powder layer in coplanar contact with a current collector; spraying a binder in selected areas of the densely packed powder layer to form an electrode, wherein the selected areas include dark inked areas and / or light inked areas; and drying and curing the electrode.

[0071] In one aspect of the present invention, jetting the binder in the dark inked area includes jetting the binder at each pixel of the selected area, and jetting the binder in the light inked area includes jetting the binder at a portion of the pixels of the selected area.

[0072] In one aspect of the invention, the method includes slitting and slotting the electrode, and wherein spraying the binder in selected areas includes not spraying binder in areas of the electrode that are removed during slitting and slotting.

[0073] In one aspect of the invention, the method includes recovering powder from the region of the electrode removed during slitting and groove forming.

[0074] In one aspect of the invention, drying and curing the electrode comprises drying and using an energy source, wherein drying is completed before curing is completed.

[0075] In one aspect of the invention, forming a densely packed powder includes dispensing powder onto the current collector and compacting and leveling the dispensed powder.

Claims

1. A method comprising: applying a powder onto a first side of a current collector, wherein the powder comprises particles of an electroactive material; jetting an ink including a binder in a controlled pattern onto the powder-coated first current collector; as well as An electrode is formed including patterned regions of bonded powder and patterned regions of unbonded powder, wherein the unbonded powder is secured between the patterned regions of bonded powder.

2. The method of claim 1, further comprising: A second side of the current collector is coated with powder, the second side being opposite to the first side, and wherein coating the powder onto the first side of the current collector comprises coating with a first powder, and coating the powder onto the second side of the current collector comprises coating with a second powder, wherein the composition of the first powder is different from the composition of the second powder.

3. The method of claim 2, wherein the first powder comprises a cathode electroactive material and the second powder comprises an anode electroactive material.

4. The method of claim 1, further comprising: Slitting and grooved the current collector prior to applying powder to the first side or the controlled pattern of the current collector includes not spraying ink in the area of ​​the electrode removed during slitting and grooved, and the method also includes recovering powder from the area of ​​the electrode removed during slitting and grooved.

5. The method of claim 1, wherein the ink further comprises one or more of a conductivity enhancing dopant or a thermally activated catalyst.

6. The method of claim 1, wherein the method is performed using a roll-to-roll process or using a build box.

7. A method as claimed in claim 1, wherein jetting ink in the controlled pattern includes jetting ink in a dark ink area and / or a light ink area, and wherein jetting ink in the dark ink area includes jetting ink at each pixel in the dark ink area, and jetting ink in the light ink area includes jetting ink at a portion of pixels in the light ink area.

8. The method of claim 1 further comprising drying and curing the electrode, wherein drying and curing the electrode comprises drying and using an energy source, wherein drying is completed before curing is completed.

9. The method of claim 1, wherein applying powder to the first side of the current collector comprises dispensing powder onto the current collector and compacting and leveling the dispensed powder.

10. An electrode for a battery cell, comprising: Current collector; a three-dimensional pattern comprising a volume of bound electroactive material particles fixedly coupled to the current collector; Unbound electroactive material particles are secured between bound electroactive material particles within the volume.

11. An electrode as described in claim 10, wherein the volume of bound electroactive material particles is configured to determine the path of ions through the electrode, and wherein the distance between the volume of bound electroactive material particles determines the density of the unbound electroactive material particles fixed between the volume of bound electroactive material particles.

12. The electrode of claim 11, wherein the density of the unbound electroactive material particles is configured to allow swelling of the unbound electroactive material particles.

13. The electrode of claim 10, wherein the volume of bound electroactive material particles includes a conductivity enhancing dopant.

14. The electrode of claim 10, wherein the electrode is a multilayer electrode including the three-dimensional pattern, the multilayer electrode fixedly coupled to a first side of the current collector and fixedly coupled to a second side of the current collector, the first side being opposite to the second side.

15. The electrode of claim 10, wherein the three-dimensional pattern is a periodic engineered structure configured to retain unbound particles, provide strength to the battery cell including the electrode, and direct current flow through the electrode.

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