Electrode and Separator Stacking Machine for High-Speed ​​Battery Manufacturing

Abstract

Disclosed are embodiments of battery stacker machines, including z-fold stacker machines, configured to provide rotational transfer of battery layers to reduce scrubbing. In some embodiments, the layers are bent onto an arcuate surface using a vacuum or other force. The arcuate surface is then rotated to release the layers at a desired transfer location. For example, the desired transfer location may be on the top of the stack or on another arcuate gripper surface.

Description

[Technical Field]

[0001] This application claims priority to U.S. Provisional Application No. 63 / 380,359, filed October 20, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure generally relates to a battery stacker machine for stacking anodes, cathodes, and separators. The present disclosure also relates to a method and gripper for battery stacking. In particular, the present disclosure relates to rolling transfer of battery layers. [Background technology]

[0003] Prismatic batteries are formed by interleaving alternating layers of cathodes, insulating separators, and anodes. Thus, to form a stack, the separator is a continuous layer that is folded back and forth (z-folded) between the alternating anode and cathode layers. The battery design itself precludes aligning the edges of the individual layers to a common reference. To avoid malfunction, there must be no electrical contact between an anode and an adjacent cathode. Therefore, the cathodes and anodes are typically mismatched in size and centered relative to one another, with a 1-2 mm physical boundary between adjacent negative and positive electrode layers.

[0004] Conventional z-fold stacker machine mechanisms are limited in throughput by their system architecture, which repeats a placement / clamp / fold sequence. Using one transfer device per electrode, these previous attempts involved various clamping and holding techniques to hold the stack in place while another electrode was placed on top, reducing throughput. Furthermore, synchronization of each transfer device and separator feeder was difficult.

[0005] One example of a previous attempt is described in U.S. Patent Application Publication No. 2006 / 0051652 A1 to Samuels. The 2006 / 0051652 publication describes an interleaving machine for forming stacks. Figure 1 of Samuels shows a first pickup and place device for handling the cathode stack, a second pickup and place device for handling the anode stack, and a centrally located elevator for inserting separators between alternating anode and cathode layers. In one embodiment, Samuels describes a Bernoulli pickup and place device for handling the electrodes. A carriage facilitates horizontal movement of the pickup and place devices.

[0006] Another example is Korean Patent No. 101220981, which also describes a stacking device having a first vacuum transfer means for the anode and a second vacuum transfer means for the cathode. Each vacuum transfer means can be rotated to fold the separator onto the stack. Summary of the Disclosure

[0007] In one aspect, a method for forming a battery electrode and separator stack is disclosed, the method being performed by a battery stacker or by a gripper of the battery stacker. The method includes applying a force to a battery layer via an arcuate surface to move the battery layer from a first position and bend the battery layer into a conforming position on the arcuate surface. The method further includes rotating the arcuate surface together with the battery layer to a second position while the force maintains the battery layer bent into the conforming position on the arcuate surface. The method further includes transferring the battery layer from the conforming position on the arcuate surface to a receiver surface, the transferring including releasing the force applied via the arcuate surface.

[0008] In some embodiments, the receiver surface is another arcuate surface, and transferring includes applying a force with the arcuate receiver surface to bend the layer into a conforming position on the receiver surface.

[0009] In some embodiments, the receiver surface is a stack of battery electrodes and separators that includes a substantially flat surface, and the transferring includes transferring the battery stack to a non-flexed position.

[0010] The method may also include eccentrically rotating the arcuate surface so that it translates laterally and vertically relative to the receiver surface.

[0011] The method also includes applying the force by drawing a vacuum through the opening in the arcuate surface.

[0012] The method may also include a battery layer having discrete electrodes on a continuous separator sheet.

[0013] The method may also include a battery layer having discrete electrodes on discrete separator sheets.

[0014] The method also includes applying a vacuum through an opening in a laterally reciprocating gripper to apply a force.

[0015] The method also includes gradually applying positive pressure through the openings in the arcuate surface as a function of lateral position.

[0016] The method may also include a first position that is a vertical material transfer location defined by an arcuate surface opposing another arcuate surface that functions as a pick and place device.

[0017] The method may also include performing the applying of force, rotating, and transferring in association with a first lateral reciprocating roller on a first side of the battery stacker, the method further including repeating the applying of force, rotating, and transferring in association with a second lateral reciprocating roller on a second side of the battery stacker.

[0018] The method may also include applying a force by drawing a vacuum through holes on the continuous separator sheet to flex the battery layers.

[0019] In one aspect, a battery stacker is disclosed that includes an arcuate surface configured for application of a force to pull a battery layer from a first position and bend it to a conforming position on the arcuate surface, an axis about which the arcuate surface is rotatable while the force maintains the battery layer bent in the conforming position to rotate the battery layer to a second position, and a receiver surface for receiving the battery layer in response to release of the force to transfer the battery layer from the conforming position on the arcuate surface to the receiver surface.

[0020] In some embodiments, the receiver surface may be another arcuate surface of the battery stacker, which may include means for applying force to the battery layers. In some embodiments, the receiver surface may be the same or substantially the same as the arcuate surface over which the battery layers are transferred. In some embodiments, the receiver surface is a stack of battery electrodes and separators that includes a substantially flat surface.

[0021] The battery stacker may also include a rotatable multi-faceted gripper including an arcuate surface. The rotatable multi-faceted gripper may be eccentrically rotatable.

[0022] The battery stacker may include left and right eccentric rotatable multi-faceted grippers that function as pick and place devices.

[0023] The battery stacker may be a z-fold stacker.

[0024] The battery stacker may also include a force as a vacuum force applied through an opening in the arcuate surface.

[0025] The battery stacker may also include a force, the first force, and the arcuate surface configured to apply a second force as a positive pressure applied through an opening in the arcuate surface.

[0026] In one aspect, a rotatable multi-sided gripper for transporting battery layers is disclosed. The gripper comprises a body having three angularly spaced arcuate gripper faces and three angularly spaced truncated sides. Each arcuate gripping surface includes means for applying a force to a battery layer positioned on the gripping surface to maintain the battery layer in a conforming position on the arcuate surface.

[0027] In some embodiments, each arcuate gripper surface further comprises means for applying a second force as a positive pressure on the battery layer to release and / or transfer the battery layer to the receiver surface.

[0028] The disclosed embodiments utilize the physical flexibility of the stacked materials to perform the material handoff through a rolling motion. There are four cases of rolling handoff that can utilize the disclosed technology: (1) transfer from a moving roller to a stationary flat surface; (2) transfer from a stationary flat surface to a moving roller; (3) transfer from a stationary roller to a moving flat surface; or (4) transfer from a moving flat surface to a stationary roller. The disclosed material transfers are performed without scrubbing, i.e., with minimal relative motion between the roller and the flat surface.

[0029] Conventional z-fold stacker technology typically uses a reciprocating motion (e.g., pick and place) to build stacks from discrete electrodes. Therefore, in some embodiments, it may be desirable to use a continuous rotary motion as an alternative to a reciprocating motion.

[0030] Additional aspects and advantages will become apparent from the following detailed description of the embodiments, which proceeds with reference to the accompanying drawings. [Brief explanation of the drawings]

[0031] To easily identify the description of any particular element or operation, the most significant digit(s) in a reference number refers to the number of the figure in which that element is first introduced.

[0032] [Figure 1]FIG. 1 illustrates an isometric view of a z-fold stacker machine according to one embodiment. [Figure 2] 2A-2C are a series of side views illustrating a series of different lateral material transfer positions as the multi-faceted gripper of FIG. 1 rotates eccentrically counterclockwise, according to one embodiment. [Figure 3] FIG. 1 illustrates an isometric view of an eccentrically rotatable multi-faceted gripper assembly, according to one embodiment. [Figure 4] FIG. 1 illustrates an isometric view of a z-fold stacker machine with separate stacks for each electrode type, according to one embodiment. [Figure 5] 5 is a set of detailed views of the z-fold stacker machine of FIG. 4 during a stacking sequence. [Figure 6] FIG. 10 is an isometric view of a z-fold stacker machine according to another embodiment. [Figure 7] FIG. 1 is a side elevation view of a Reuleaux triangle according to one embodiment. [Figure 8] 8 is a graph showing scrubbing as a function of angular position of the Reuleaux triangle shown in FIG. 7. [Figure 9] FIG. 8 is a side elevation view of the center of gravity of the Reuleaux triangle shown in FIG. [Figure 10] FIG. 10 is an annotated side elevation view of a portion of a centroid circle and a non-circular orbital path, according to one embodiment. [Figure 11] 11 is a side elevational view showing the entire center of gravity circular orbital path of FIG. 10 inscribed in the center of gravity non-circular orbital path of FIGS. 9 and 10. FIG. [Figure 12] FIG. 12 is a side elevation view of the Reuleaux triangle of FIG. 7 annotated with angular position lines for empirically determining the arcuate surface without scrubbing and with the centroid circular orbit path shown in FIG. 11 . [Figure 13] FIG. 13 is a side elevational view showing the position line of FIG. 12 in more detail. [Figure 14] FIG. 14 is a side elevational view showing in more detail the intersection of the position lines shown in FIGS. 12 and 13. [Figure 15] FIG. 15 is a side elevational view showing in more detail the angle formed at the intersection shown in FIG. 14. [Figure 16]FIG. 16 is a side elevation view of a modified arcuate surface empirically derived using the technique shown in FIGS. 9-15. [Figure 17] FIG. 17 is an isometric view showing the modified arcuate surface of FIG. 16 deployed on three mutually angularly spaced side surfaces. [Figure 18] FIG. 10 is an isometric view of a z-fold stacker machine according to another embodiment having a reciprocating carriage. [Figure 19] 1A-1C are a set of isometric views showing a reciprocating carriage and vacuum roller in a series of stacking positions according to one embodiment. [Figure 20] 20A-20C are a set of side elevation views showing the vacuum roller of FIG. 19 in a series of stacked positions, according to one embodiment. [Figure 21] 10A-10C are a set of isometric views showing a z-fold stacker machine during a stacking sequence according to another embodiment. [Figure 22] FIG. 1 is a flow diagram of a process according to one embodiment. [Figure 23] FIG. 1 is a flow diagram of a process according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0033] 1 shows a simplified diagram of a z-fold stacker machine 100 according to one embodiment. The z-fold stacker machine 100 includes a first electrode delivery system 102 for providing a first type of electrode material 104 (e.g., copper anode 106), a second electrode delivery system 108 for providing a second type of electrode material 110 (e.g., aluminum cathode 112), and a central assembly system 114 for providing a separator 116 for z-folding with the electrodes to form a battery stack 118. In the z-fold configuration, the separator 116 is not singulated into individual layers, but instead forms a single continuous layer that is folded back and forth between alternating electrodes (anodes and cathodes).

[0034] In the battery stack 118, the copper anodes 106 and aluminum cathodes 112 are typically mismatched in size and center-aligned with one another (i.e., no common edge reference), resulting in a 1-2 mm physical boundary between adjacent anode and cathode layers. The z-fold stacker machine 100 is designed to meet this center-alignment specification, typically to an accuracy of about 0.25 mm. The z-fold stacker machine 100 can accommodate a wide range of electrode sizes.

[0035] In an embodiment of the z-fold stacker machine 100, the first electrode delivery system 102 includes a first roll 120 of electrode material 104. As the electrode material 104 is drawn from the first roll 120 by a conveyor 122 or other transport mechanism, a laser ablation device 124 cuts the electrode material 104 to form first electrodes 126 that are singulated from the first roll 120.

[0036] Similarly, the second electrode delivery system 108 includes a second roll 128 of electrode material 110. As the electrode material 110 is drawn from the second roll 128 by a conveyor 130 or other transport mechanism, a laser ablation device 132 cuts the electrode material 110 to form second electrodes 134 that are singulated from the second roll 128.

[0037] The central assembly system 114 includes three eccentrically rotatable multi-faceted grippers, which are described in further detail below. Initially, however, each eccentrically rotatable multi-faceted gripper has a longitudinal axis that is offset from the axis of rotation such that the eccentrically rotatable multi-faceted gripper moves in a circular path while sequentially presenting different arcuate gripper surfaces to lateral material transfer positions.

[0038] In this example of z-fold stacker machine 100, first eccentric rotatable multi-surface gripper 136 and second eccentric rotatable multi-surface gripper 138 function as pick and place devices that move electrodes from horizontal positions on their respective conveyors 122 and 130 to vertical positions that allow them to be transferred to a central eccentric rotatable multi-surface gripper 140 that also selectively engages a draped portion 142 of separator 116. Central eccentric rotatable multi-surface gripper 140 then places the material onto battery stack 118.

[0039] In this embodiment, the separator 116 is fed along the same side as the first electrode 126, but at twice the speed—that is, twice the length of separator per electrode length. The unconstrained portion of the separator (between the battery stack 118 and the electrode being picked) is held in tension by air pressure before being folded onto the battery stack 118 by the orbital motion of the central eccentrically rotatable multi-faceted gripper 140. The inherent flexibility of the material allows for picking and placing with a rolling motion in place while the central eccentrically rotatable multi-faceted gripper 140 maintains continuous orbital motion. Because the central assembly system 114 uses continuous rotational motion, the z-fold stacker machine 100 is capable of high throughput, high efficiency, and reduced forces and vibrations associated with reciprocating motion.

[0040] As described below, loading and unloading of layers from the arcuate gripper surface into the battery stack 118 is accomplished substantially without scrubbing. Scrubbing occurs when one layer at the top of the stack is pulled laterally (i.e., dragged or slid) relative to the layer below. For example, in some embodiments, the change in distance from the initial contact point of the two layers to their final relative positions is less than about 100 μmin. However, one skilled in the art will understand that different scrubbing tolerances may be achieved using different battery layer materials and manufacturing specifications.

[0041] The rotating parts move continuously at a constant rotational speed, improving throughput. The target cycle time of 0.1 seconds (electrode-to-electrode) is approximately six times faster than conventional systems. This means that a typical stack of 100 layers can be completed in 10 seconds instead of 60 seconds.

[0042] In some embodiments, to maintain overall factory throughput, completed stack assemblies are quickly removed and replaced with identical stack elevator assemblies by a linear shuttle that traverses the feed direction. This optional shuttle maximizes utilization of the stacking process. Downstream process steps (e.g., wrapping, taping, and other steps) can then be performed in parallel with building subsequent stacks.

[0043] 2 shows in more detail the sequence of different lateral material transfer positions 200 as the central eccentrically rotatable multi-faceted gripper 140 moves eccentrically while rotating counterclockwise. Each position in the sequence of different lateral material transfer positions 200 is described in detail below.

[0044] 2, first eccentrically rotatable multi-faceted gripper 136 and second eccentrically rotatable multi-faceted gripper 138 are omitted for simplicity. Also, the movement of first electrode 126 and second electrode 134 is simplified as shown as being vertically lowered to contact the arcuate gripper surface of central eccentrically rotatable multi-faceted gripper 140. However, considering z-fold stacker machine 100, one skilled in the art will understand that the electrodes of z-fold stacker machine 100 are moved from a horizontal orientation to a vertical orientation when first eccentrically rotatable multi-faceted gripper 136 rotates eccentrically counterclockwise and when second eccentrically rotatable multi-faceted gripper 138 rotates eccentrically clockwise.

[0045] The first position 202 is established when the first eccentrically rotatable multi-faceted gripper 136 (FIG. 1) rotates, successively presenting its three arcuate gripper surfaces above a conveyor 122 (FIG. 1) that transports the first electrode 204 to a position below an opposing one of the arcuate gripper surfaces of the first eccentrically rotatable multi-faceted gripper 136. The first electrode 204 is picked up (e.g., using vacuum pressure or electrostatic attraction) while the arcuate gripper surface moves eccentrically toward the drape portion 142 of the separator 116 as it rotates upward (i.e., counterclockwise).

[0046] At the same time, the central eccentrically rotatable multi-surface gripper 140 has its first arcuate gripper surface 206 rotated downward and eccentrically moved toward the drape portion 142 as the idler roller 208 is adjusted to maintain tension on the separator 116. When the two opposing arcuate gripper surfaces meet at the left material transfer position 210, the first electrode 204 is released from the first eccentrically rotatable multi-surface gripper 136 and simultaneously drawn onto the central eccentrically rotatable multi-surface gripper 140 (e.g., by a vacuum being drawn through the relatively porous drape portion 142 underlying the first electrode 204). Thus, the first arcuate gripper surface 206 holds the first electrode 204 and a fixed portion 212 of the separator 116. Additionally, the second arcuate gripper surface 214 holds the second electrode 216 in an upwardly facing intermediate right position 218 oriented 120° clockwise from the left material transfer position 210 .

[0047] With the first electrode 204 and fixed portion 212 held by the central eccentric rotatable multi-faceted gripper 140, the central eccentric rotatable multi-faceted gripper 140 continues to rotate eccentrically downward toward the battery stack 118, establishing a second position 220. Thus, the first electrode 204 and fixed portion 212 pass through an intermediate left position 222, and the second electrode 216 reaches a top center position 224. A jet of air from an air knife, vacuum, or similar force is applied to the slack portion 226 of the separator 116 and directed across the top 228 of the battery stack 118, thereby imparting a z-bend to the slack portion 226 in preparation for placing the first electrode 204 on the battery stack 118.

[0048] As the central eccentric rotatable multi-faceted gripper 140 continues to rotate to the third position 230, the first electrode 204 and fixed portion 212 move further downward and to the right. The second electrode 216 moves closer to the material transfer position 210 on the left side.

[0049] In the fourth position 232, the central eccentric rotatable multi-faceted gripper 140 is in its lowest central position 234, at which point the first electrode 204 and fixed portion 212 are released onto the top 228 of the battery stack 118. The z-elevator (not shown) for the battery stack 118 decreases downward as layers are added so that placement always occurs at the same height. As mentioned above, the release at the lowest central position 234 occurs with substantially no lateral movement to avoid scrubbing.

[0050] Upon release, the central eccentrically rotatable multi-faceted gripper 140 rotates and continues to move toward the second eccentrically rotatable multi-faceted gripper 138 ( FIG. 1 ). A fifth position 236 shows the second electrode 216 and second arcuate gripper surface 214 at the left material transfer position 210 for loading without substantial scrubbing. Notably, the second arcuate gripper surface 214 is not used to hold any portion of the separator 116. In some embodiments, an air jet or vacuum pushes the separator 116 away from the second arcuate gripper surface 214, as shown in a sixth position 238. This creates space for the second electrode 216 to move toward the top 228, as shown in a seventh position 240. The seventh position 240 also shows how the third electrode 242 is attached to the first arcuate gripper surface 206 at the right material transfer position 244. The third electrode 242 is the same type of material as the second electrode 216 (e.g., aluminum cathode 112, FIG. 1), both of which are provided by the second eccentric rotatable multi-faceted gripper 138 (FIG. 1).

[0051] Finally, at eighth position 246, second electrode 216 is released onto cell stack 118 without scrubbing. Third electrode 242 is rotated upward and eccentrically away from right-hand material transfer position 244, and fourth electrode 248 (same type as first electrode 204) is moved by first eccentrically rotatable multi-faceted gripper 136 ( FIG. 1 ) to left-hand material transfer position 210, so that the process repeats when third arcuate gripper surface 250 reaches first position 202.

[0052] 3 shows an eccentrically rotatable multi-faceted gripper assembly 300. The eccentrically rotatable multi-faceted gripper assembly 300 includes an internal ring gear 302, external planetary gears 304, a central eccentrically rotatable multi-faceted gripper 140 (e.g., the central eccentrically rotatable multi-faceted gripper 140 of FIGS. 1 and 2 ), a counterbalance 306, and an input shaft 308 that establishes a pivot axis of rotation 310. In this example, the central eccentrically rotatable multi-faceted gripper 140 is a six-sided non-cylindrical body 312 that includes three angularly spaced-apart arcuate gripper faces 314 and three angularly spaced-apart truncated sides 316.

[0053] The body 312 has an offset longitudinal axis 318 spaced from the pivot axis 310 to establish eccentric orbital motion guided by the outer planetary gears 304 within the inner ring gear 302. A mounting block 320 houses the inner ring gear 302 and provides an air pressure inlet port 322 and an air pressure outlet port 324.

[0054] Without the truncated sides 316, the arcuate gripper surface 314 may form a trihedron resembling a triangle with curved sides. However, in the body 312, the apex of the triangle is truncated for clearance and mass reduction, since it does not perform a stacking-related function. The particular design of the truncated surface may be tailored to accommodate the tension on the unconstrained separator (i.e., the tension on the fixed portion 212 and the slack section 226 (FIG. 2)).

[0055] The arcuate gripper surfaces 314 include pneumatic gripper openings 326 configured to apply vacuum and pressure (obtained from pneumatic inlet port 322 and pneumatic outlet port 324) to hold and release the layer from the two active arcuate gripper surfaces 314, as described above with reference to FIG. 2.

[0056] In some embodiments, continuous negative and positive pressures are applied to the ports, however these pressures are supplied automatically and periodically as a function of the orbital position of the central eccentric rotatable multi-faceted gripper 140 via fluid communication channels (not shown) in the body 312 that align with fixed internal port locations (not shown) as the central eccentric rotatable multi-faceted gripper 140 orbits.

[0057] 4 shows a variation of a z-fold stacker machine 400 in which the electrodes are provided in separate stacks rather than by conveyor transport. In other embodiments, the separators may be singulated (i.e., not z-folded).

[0058] To illustrate examples of the holding and hand-off forces applied during transport of the electrode and separator portions, FIG. 5 shows the z-fold stacker machine 400 in more detail between the eighth position 246, the first position 202, and the second position 220, respectively.

[0059] In eighth position 246, first battery layer 502 (e.g., a graphite-coated copper or aluminum electrode) is bent into a conforming position on first arcuate gripper surface 504. The dashed arrow indicates the application of a vacuum force (negative pressure) that pulls first battery layer 502 onto first arcuate gripper surface 504. In this example, drape section 142 is unaffected by the vacuum force, although in other embodiments, drape section 142 may also be pulled toward first arcuate gripper surface 504 (see, e.g., fourth electrode 248 and separator 116 in FIG. 2 ).

[0060] In the first position 202, the top 506 of the first arcuate gripper surface 504 applies a negative pressure, while the bottom 508 applies a positive pressure (indicated by the solid arrows). At the same time, the top 510 of the second arcuate gripper surface 512 applies no pressure, and the bottom 514 applies a negative pressure. Thus, the central eccentric rotatable multi-faceted gripper 140, via its second arcuate gripper surface 512, applies a negative force to pull the battery layer from its left material transfer position 210 on the first arcuate gripper surface 504 and bend it into a conforming position on the second arcuate gripper surface 512.

[0061] In the second position 220, the adjustment of pressure causes the material to move from one surface to the other. The first arcuate gripper surface 504 applies only positive pressure 516, and the second arcuate gripper surface 512 applies only negative pressure 518. The positive pressure 516 from the first arcuate gripper surface 504 also acts to encourage a z-fold 520 at the slack portion 226 (FIG. 2).

[0062] From the second position 220, while the force of the negative pressure 518 maintains the battery layer bent in the conforming position, the central eccentric rotatable multi-faceted gripper 140 rotates the second arcuate gripper surface 512 along with the battery layer to a second position (i.e., the bottom-most central position 234 in FIG. 2 ) across the left material transfer position 210, at which point the negative pressure 518 is released while applying an opposing force (not shown) to transfer the battery layer from the conforming position on the second arcuate gripper surface 512 to an unbent position on a flat receiver surface (e.g., the top 228 of the battery stack 118). This allows for substantially scrubbing-free transfer of the battery layer from the conforming position on the arcuate surface to the unbent position on the receiver surface for deposition onto a stack of battery electrodes and separators.

[0063] Note that in some embodiments, the opposing force (e.g., positive pressure) is optional. For example, depending on the rotation speed, gravity may be sufficient to separate the material from the arcuate surface, and releasing the force during rotation may be sufficient to position the electrodes on top of the battery stack 118.

[0064] 6 shows a z-fold stacker machine 600 according to another embodiment. In this example, instead of the first eccentric rotatable multi-surface gripper 136 and the second eccentric rotatable multi-surface gripper 138, a vacuum conveyor 602 is used to move the electrodes vertically for the central eccentric rotatable multi-surface gripper 140 to grip and position the stack.

[0065] As previously described, the eccentrically rotatable multi-faceted gripper 328 includes an arcuate gripper surface 314 for continuous rotational motion. One candidate shape for a surface for a continuous rotational motion system is based on a Reuleaux triangle 700, as shown in FIG. 7 . The boundary of the Reuleaux triangle 700 is a curve of constant width based on an equilateral triangle. All points on one side are equidistant from the vertex on the opposite side. The Reuleaux triangle 700 allows a rotor to form within a square, allowing for a complete rotation while remaining within the square, always touching all four sides of the square. In practice, the central portion of each curved surface approximately matches the length of the electrode (measured in the feed direction), allowing the gripper surface to accommodate a range of lengths (theoretically, up to r*n / 3, where r is the length of the equilateral triangle side in the Reuleaux triangle 700 and also the radius of curvature of the curved surface). Generally, shorter electrode lengths allow for higher throughput, but this is a function of the electrode design, specifically the placement of the terminal tabs located transverse to the feed direction.

[0066] However, systems based on pure Reuleaux triangles have two problems. First, the orbital motion at the center of the triangle is not a simple circle, but a combination of four elliptical segments. Second, the rotor's action on the square electrodes is not pure rotation without scrubbing. For pure rotation, the linear distance traveled by the vertex along one side of the square must be equal to the length of the opposite arc as the vertex rotates along the opposite side. Due to the relative linear motion between the curved surface and the pickup or placement electrode, any difference results in scrubbing.

[0067] 7 and 8 show how scrubbing can be quantified. Consider a Reuleaux triangle 700 of side r that continuously circles the inside of a square perimeter 702 of side r. Electrodes are selected from the left and right sides of the square perimeter 702 and are placed in a stack (not shown) on the bottom side of the square perimeter 702. For a typical half angle Θ where Θ varies between 0° (vertical contact at the center of the stack) and 30° (π / 6), the rotational (arc) distance traveled as Θ increases from 0° is r*Θ. The distance X is given by X = rsin(π / 6 + Θ) = r / 2*(cosΘ + √3 sinΘ). Subtracting r / 2 from X gives the linear distance traveled: r / 2*(cosΘ + √3 sinΘ-1). Scrubbing is the difference between the two, i.e., r / 2*(2Θ+1-cosΘ-√3 sinΘ).

[0068] Figure 8 shows that the scrubbing effect is significant as a percentage of r. Because scrubbing can be mathematically characterized, it can be compensated for, but it involves additional reciprocating motion of the two input positions and the output stack. Similarly, complex elliptical orbits of the rotor can be achieved with sophisticated motion control or cam designs, but simple rotary motion is preferred for its simplicity and reliability. Both of these effects are addressed in the modified Reuleaux triangle described below.

[0069] The first step in designing a modified Reuleaux triangle is to create a non-slip contour path for the shape's center of gravity. This non-slip path ensures pure rolling motion on a curved surface. This is achieved by assuming that the rolling traverse distance is equal to the lateral movement of the upper vertex of the Reuleaux triangle. This is similar to a non-slip wheel traversing a distance, where the specification is that the arc length of the wheel that contacts the ground during movement is equal to the lateral distance of the axle traveled.

[0070] FIG. 9 shows how a non-circular center of gravity orbit path 900 in X and Y can be expressed as a function of theta: X = (r * Θ) - (rcentroid * sin(Θ)); Y = rcentroid * cos(Θ). Each of the four arc-shaped paths 902 is the result of graphing the non-circular center of gravity orbit path 900 for appropriate values ​​of r and rcentroid. Note that for any given one of the four sides (perimeter of a square) defined by a Reuleaux triangle, Θ is defined from ±15° from its center position, which is the extent of the path before the adjacent curves of the triangle meet the next orthogonal side of the larger square. FIG. 9 shows that the non-circular center of gravity orbit path 900 has sharp corners, which are not suitable or practical for motion using a standard gear-drive transmission assembly.

[0071] 10-17 thus show an example of an empirical method for smoothing a non-circular center of gravity orbit path 900 by inscribing a circular center of gravity orbit path 1000 (FIG. 10) as an orbit driven using the eccentric or planetary gear system described above.

[0072] To achieve zero scrubbing, constant angular velocity gear motion, and counter-rotation of the proportional center of gravity Θ during orbit, Figure 10 shows that the arc length of the arcuate path 1002 is directly proportional to the rotation angle Θ of the Reuleaux triangle. For simplicity, both paths 902 and 1002 are shown divided into 1° increments of Θ. The total Θ span is 30° (±15°), which corresponds to the total rolling contact area on one side of the outer square before contact is made on the adjacent side of the square.

[0073] Figure 11 shows an outline 1100 of the non-circular center of gravity trajectory path 900 and the circular center of gravity trajectory path 1000 to compare the complete trajectories between the original and modified paths. Because the original Reuleaux triangle surface cannot provide consistent non-scrubbing contact when following the arcuate path 1002, the new circular center of gravity trajectory path 1000 should also have a new contact rolling surface design. Figures 12-17 show how a new arcuate contact surface profile can be created by first setting the Reuleaux triangle to Θ = -15°.

[0074] 13 shows in more detail that to map the non-scrubbing rolling surface onto the trajectory of the circular centroid orbit path 1000, a set of lines 1302 are projected from each zero position on the circular centroid orbit path 1000 to the surface 1304 to be rolled. To ensure no scrubbing, the projected lines are equally spaced 1306 for each common increment of Θ, starting from a tangent intersection 1308 of the vertical projection 1310.

[0075] 14 shows how line intersections 1402 are created that correspond to the Θ positions of the circular center of gravity orbit path 1000. These corresponding line intersections 1402 vary from 15° to 0° from vertical, corresponding to the new Θ orientation.

[0076] Figure 15 shows how angle α is defined. This angle corresponds to the angle between the set of lines 1302 and the corresponding line intersection 1402 for each Θ location. The following table can be constructed to map angle Θ to the length D of the projection line and the angle α of the projection line from the new centroid. Using each D and a in the table, Figure 16 shows how a new non-scrub surface 1602 can now be constructed around the new centroid.

[0077] [Table 1]

[0078] 17 shows how patterned surfaces 1602 on three sides spaced at 120° angles about the center of gravity result in a trilobal shape 1702 suitable for prescribed orbital and centroidal rotational motion. In some embodiments, trilobal shape 1702 can be part of a hollow or solid body (e.g., body 312, see FIG. 3) to provide a prismatic shape with non-scrubbing rolling surfaces on three outer surfaces that revolves in a circular orbit (i.e., amenable to gear transmission). In other embodiments, trilobal shape 1702 can have its sides connected by spokes on a hub (not shown).

[0079] In other embodiments, the number of sides may be greater. Those skilled in the art will also appreciate that closed-form analytical techniques may also be employed to develop the arc gripper surface shape, instead of the empirical approach described above.

[0080] 18-20 show another embodiment of a z-fold stacker machine 1800. In this embodiment, instead of using a prismatic design as previously described, a reciprocating carriage 1802 shuffles from side to side to pick up electrode layers and place them into a stack 1804 while folding the separator (shown in FIGS. 19 and 20).

[0081] 19 shows a sequence 1900 of reciprocating motion of the reciprocating carriage 1802. The reciprocating carriage 1802 includes a first gripper 1902 for the first electrode 1904, a second gripper 1906 for the second electrode 1908, and a gap for z-folding the separator 1910 as the reciprocating carriage 1802 moves left and right.

[0082] Figure 20 shows how a z-fold stacker machine 1800 achieves rotational transport of battery layers to reduce scrubbing. For clarity, Figure 20 omits the shuttle carriage 1802.

[0083] In the first position 2002, the first electrode 1904 is oriented horizontally above the first vacuum roller 2006, where it can be lifted by the negative pressure applied by the first gripper 1902 (FIG. 19). Simultaneously, the second electrode 1908 is introduced to the second vacuum roller 2006.

[0084] At the second position 2008, the first electrode 1904 is released by the first vacuum roller 2004 and moved onto the stack 1804. At the same time, the second vacuum roller 2006 applies a vacuum force through its arcuate surface to the second electrode 1908, causing it to move from its initial position and bend to a conforming position on the arcuate surface.

[0085] The third position 2010 is then reached as follows: While the vacuum force maintains the second electrode 1908 deflected in the conforming position, the second vacuum roller 2006 rotates such that the arcuate surface holding the second electrode 1908 moves to a second position (e.g., horizontal) that is transverse to the first position in which the second electrode 1908 was introduced.

[0086] To transition to the fourth position 2012, the second vacuum roller 2006 releases its vacuum force while the second gripper 1906 (FIG. 19) applies a vacuum force to provide a substantially scrubbing-free transfer of the second electrode 1908 from a conforming position on the arcuate surface to a non-bent position on the receiver surface of the second gripper 1906 for depositing the second electrode 1908 onto the battery electrode and separator stack 1804.

[0087] FIG. 21 shows another z-fold stacker machine 2100 including a pair of reciprocating rollers 2102 during a stacking sequence. The pair of reciprocating rollers 2102 function similarly to the reciprocating carriage 1802, but instead of lifting and positioning electrodes, each of the reciprocating rollers 2102 rotates with a curved electrode that conforms to its surface (e.g., by applying vacuum force through pneumatic gripper openings, not shown) while gradually releasing negative pressure and applying positive pressure as the roller moves across the top of the stack 2104. For example, the right-side roller 2106 gathers the electrodes provided on its right side and applies vacuum force to the electrodes, causing them to rotate on the stack 2104 while shuffling them leftward, gradually releasing the vacuum force while applying positive pressure as a function of lateral position on the stack 2104.

[0088] 22 shows a method 2200 (which may be performed by any one of stacker machines 100, 400, 600, 1800, or 2100 and / or a multi-surface gripper) for forming a battery electrode and separator stack. In block 2202, method 2200 applies a force to the battery layer via the arcuate surface to move the battery layer from a first position and bend it into a conforming position on the arcuate surface. In block 2204, while the force maintains the battery layer bent in the conforming position, method 2200 rotates the arcuate surface along with the battery layer to a second position that is transverse to the first position. In block 2206, method 2200 releases the force while optionally applying an opposing force to provide a substantially scrubbing-free transfer of the battery layer from the conforming position on the arcuate surface to an unbent position on a receiver face surface for deposition into the battery electrode and separator stack. The method may also include eccentrically rotating the arcuate surface so that it moves laterally and vertically relative to the receiver surface.

[0089] FIG. 23 shows a method 2300 (which in some embodiments can be implemented by a stacker machine 100, 400, 600, 1800, or 2100 and / or a multi-surface gripper) for transporting battery layers from a first location to a second location using arcuate surfaces that may be part of forming a stack of electrodes and separators.

[0090] Method 2300 comprises applying 2302 a force to the battery layer via an arcuate surface to move the battery layer from a first position and bend it to a conforming position on the arcuate surface. The applied force may be applied via vacuum in some embodiments and electrostatically in some embodiments. In some embodiments, the arcuate surface may be disposed on a multi-surface gripper and / or stacker machine.

[0091] Step 2304 includes transferring the arcuate surface with the battery layer to a receiver surface while the force maintains the battery layer bent in the conforming position. The transferring may include rotating the arcuate surface, and the rotating may include eccentric rotation. The receiver surface is positioned at a second position different from the first position. In some embodiments, the receiver surface is angularly offset from the first position. In some embodiments, the second position is transverse to the first position.

[0092] In step 2306, method 2300 comprises transferring the battery layer from the conforming position on the arcuate surface to the receiver surface, the transfer including releasing the force applied via the arcuate surface and, optionally, applying an opposing force to provide the transfer. In some embodiments, the transfer may be scrubbing-free or substantially scrubbing-free.

[0093] In some embodiments, the receiver surface is another arcuate surface. In some embodiments, the receiver surface is located on the electrode and separator stack, and the transferring comprises depositing a battery layer onto the stack of battery electrodes and separators.

[0094] The methods 2200, 2300 may also include eccentrically rotating the arcuate surface such that the arcuate surface moves laterally and vertically relative to the receiver surface.

[0095] In another embodiment, the method 2200, 2300 may also include applying the force by drawing a vacuum through an opening in the arcuate surface.

[0096] In another embodiment, the methods 2200, 2300 may also include a battery layer having discrete electrodes on a continuous separator sheet.

[0097] In another embodiment, the methods 2200, 2300 may also include a battery layer having discrete electrodes on discrete separator sheets.

[0098] In another embodiment, the methods 2200, 2300 may also include applying a force by drawing a vacuum through holes on the continuous separator sheet to flex the battery layers.

[0099] In another embodiment, the method 2200, 2300 may include applying the force by drawing a vacuum through an opening in a laterally reciprocating gripper.

[0100] In another embodiment, the methods 2200, 2300 may also include applying any force by gradually applying positive pressure as a function of lateral position, applied through an opening in a laterally reciprocating roller.

[0101] In another embodiment, the method 2200, 2300 may also include a first position that is a vertically oriented material transfer location defined by an arcuate surface opposing another arcuate surface that functions as a pick and place device.

[0102] In another embodiment, method 2200, 2300 may also include performing the applying of force, rotating, and transferring and / or releasing in association with a first lateral reciprocating roller on a first side of the battery stacker, and further including repeating the applying of force, rotating, and transferring and / or releasing in association with a second lateral reciprocating roller on a second side of the battery stacker.

[0103] Those skilled in the art will appreciate that many changes can be made to the details of the above-described embodiments without departing from the underlying principles of the invention. For example, embodiments may be used in other applications, including unstacking, singulation, and pick-and-place uses. The scope of the invention should therefore be determined only by the claims and their equivalents.

Claims

1. 1. A method of forming a stack of battery electrodes and separators performed by a battery stacker, comprising: applying a force to the battery layer via the arcuate surface to move the battery layer from a first position and bend the battery layer to a conforming position on the arcuate surface; rotating the arcuate surface together with the battery layer to a second position while the force maintains the battery layer bent in the conforming position; and transferring the battery layer from the matching position on the arcuate surface to a receiver surface; The method, wherein the transferring comprises releasing the force applied via the arcuate surface.

2. 10. The method of claim 1, wherein the receiver surface is another arcuate surface, and the transferring includes applying a force with the arcuate receiver surface to bend the layer into a conforming position on the receiver surface.

3. 10. The method of claim 1, wherein the receiver surface is a stack of battery electrodes and separators including a substantially flat surface, and the transferring includes transferring the battery layers to a non-flexed position.

4. 10. The method of claim 1, wherein said rotating comprises eccentrically rotating said arcuate surface such that said arcuate surface moves laterally and vertically relative to said receiver surface.

5. 10. The method of claim 1, wherein applying the force comprises drawing a vacuum through openings in the arcuate surface.

6. The method of claim 1 further comprising gradually applying positive pressure as a function of lateral position through an opening in a laterally reciprocating roller.

7. 10. The method of claim 1, wherein the first location is a vertical material transfer location defined by an arcuate surface facing another arcuate surface that functions as a pick and place device.

8. 10. The method of claim 1, further comprising: performing the applying of force, the rotating, and the transferring in association with a first laterally reciprocating roller on a first side of the battery stacker; and repeating the applying of force, the rotating, and the transferring in association with a second laterally reciprocating roller on a second side of the battery stacker.

9. an arcuate surface configured to apply a force to pull the battery layer from a first position and bend it into a conforming position on the arcuate surface; an axis about which the arcuate surface is rotatable while maintaining the battery layer bent in the conforming position such that the force rotates the battery layer to a second position; and a receiver surface for receiving the battery layer in response to release of the force and transferring the battery layer from the matching position on the arcuate surface to the receiver surface.

10. 10. The battery stacker of claim 9, wherein the receiver surface is another arcuate surface.

11. 10. The battery stacker of claim 9, wherein the receiver surface is a stack of battery electrodes and separators with substantially flat surfaces.

12. The battery stacker of claim 9 further comprising a rotatable multi-sided gripper including said arcuate surface.

13. 10. The battery stacker of claim 9, wherein the force is a vacuum force applied through openings in the arcuate surface.

14. 10. The battery stacker of claim 9, wherein the force is a first force and the arcuate surface is configured to apply a second force as a positive pressure applied through an opening in the arcuate surface.

15. 1. A rotatable multi-faceted gripper for transporting a battery layer, comprising: a body having three angularly spaced apart acute gripper surfaces and three angularly spaced apart truncated sides; 1. A rotatable multi-faceted gripper, wherein each arcuate gripper surface includes means for applying a force to a battery layer positioned on the gripper surface to maintain the battery layer in a conforming position on the arcuate surface.

16. 16. The rotatable multi-faceted gripper of claim 15, wherein each arcuate gripper surface further comprises means for applying a second force as a positive pressure to the battery layer to release the battery layer and / or transfer the battery layer to a receiver surface.

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