SYSTEM AND METHOD FOR X-RAY IMAGING OF BATTERY LAYERS DURING MANUFACTURING

An apparatus is configured to monitor a plurality of layers of a battery layer stack during manufacturing. The apparatus includes at least one X-ray source configured to generate X-rays with X-ray energies that exhibit contrast of transmission through the plurality of layers of the battery layer stack. The at least one X-ray source is configured to face a first side of the battery layer stack. The apparatus further includes at least one sensor configured to detect the X-rays transmitted through the plurality of layers. The at least one sensor is configured to face a second side of the battery layer stack.

BACKGROUND

Field

This application relates generally to monitoring battery fabrication processes.

Description of the Related Art

Batteries are becoming more important as demand for environmentally clean and portable energy storage has been increasing in popularity. As new battery containing products are released, batteries are subjected to new physical and electrical requirements. (See, e.g., A. Kwade et al., “Current Status and Challenges for Automotive Battery Production Technologies,” Nature Energy 3, no. 4, pp. 290-300 (2018).) These changes in battery requirements can cause changes in how batteries are manufactured which can have a significant impact on the yield of newer battery products. New products have increased the number of batteries being produced globally, such as battery powered vehicles, lawn care equipment, and backup storage for residential and commercial facilities. The increase in the number of batteries produced has made losses in manufacturing much more costly.

SUMMARY

In certain implementations, an apparatus is configured to monitor a plurality of layers of a battery layer stack during manufacturing. The apparatus comprises at least one X-ray source configured to generate X-rays with X-ray energies that exhibit contrast of transmission through the plurality of layers of the battery layer stack. The at least one X-ray source is configured to face a first side of the battery layer stack. The apparatus further comprises at least one sensor configured to detect the X-rays transmitted through the plurality of layers. The at least one sensor is configured to face a second side of the battery layer stack.

In certain implementations, a system comprises an apparatus comprising at least one X-ray source configured to generate X-rays and to direct the X-rays towards a first side of a battery layer stack comprising a plurality of layers. The apparatus further comprises at least one sensor configured to detect the X-rays transmitted through the plurality of layers. The at least one sensor faces a second side of the battery layer stack, the second side opposite to the first side. The system further comprises at least one battery rolling mechanism configured to fabricate the battery layer stack and a feedback subsystem. The feedback subsystem is configured to generate feedback signals in response to information from the apparatus and to transmit the feedback signals to the at least one battery rolling mechanism to maintain alignment of the plurality of layers during fabrication.

DETAILED DESCRIPTION

FIG.1schematically illustrates three example types of battery configurations of a battery10(e.g., lithium ion battery) comprising a battery layer stack20comprising a plurality of layers30in accordance with certain implementations described herein. Besides the battery layer stack20, the battery10can comprise an electrically conductive housing40(e.g., metal case; metalized foil pouch; aluminum-plastic film), a pressure relief vent50, and positive and negative anode and cathode terminals60a,b. For a battery10having a cylindrical (e.g., jelly roll) battery configuration, prismatic battery configuration, or pouch battery configuration, the plurality of layers30of the battery layer stack20can include an anode layer32, a cathode layer34, and at least one electrically insulative (e.g., plastic) separator layer36between the anode layer32and the cathode layer34. For example, the at least one separator layer36can comprise a first separator layer36abetween the anode layer32and the cathode layer34and a second separator layer36bon an opposite side of the anode layer32from the first separator layer36a. One or both of the first and second separator layers36a,bcan be wider than the cathode layer34and the anode layer32to allow for some misalignment during final assembly without the anode layer32and the cathode layer34coming into contact with each other (e.g., electrically shorting with one another). The anode layer32can be made to be wider than the cathode layer34so that the battery10can maintain its electrical properties in the case that the anode layer32and the cathode layer34become slightly misaligned. If the cathode layer34does move beyond the anode layer32, the battery10may not perform as expected. Misalignment of the anode layer32, cathode layer34, and at least one separator layer36can be a major cause of failure in battery manufacturing.

FIG.2Aschematically illustrates an example battery rolling mechanism100(e.g., winding assembly) configured to fabricate the battery layer stack20in accordance with certain implementations described herein. The battery rolling mechanism100comprises a plurality of rollers110configured to receive the layers30of the plurality of layers30(e.g., the anode layer32, the cathode layer34, the first separator layer36a, the second separator layer36b) of the battery layer stack20and to join the layers30together to form the battery layer stack20.

FIG.2Bschematically illustrates a cross-sectional view of an example edge portion of the plurality of layers30of the battery layer stack20in a plane substantially perpendicular to the plurality of layers30in accordance with certain implementations described herein. As shown inFIG.2B, during the fabrication of the battery layer stack20, the edges of two or more of the anode layer32, the cathode layer34, the first separator layer36a, the second separator layer36bcan be displaced relative to one another (e.g., the edges all of the layers30can be displaced relative to one another). For example, these displacements can be along a direction substantially perpendicular to the layers30(e.g., interlayer spacings) and/or along a direction substantially parallel to the layers30(e.g., lateral displacements). For example, as shown inFIG.2B, the edge of the first separator layer36ais to the left of the edge of the cathode layer34, the edge of the anode layer32is to the left of the edge of the first separator layer36a, and the edge of the second separator layer36bis to the left of the edge of the anode layer32. As shown inFIG.2B, the edges of the first and second separator layers36a,bcan extend beyond the edge of the anode layer32and the edge of the cathode layer34(e.g., to electrically insulate the anode layer32and the cathode layer34from one another). Other relative positions of the edges of the layers30are also compatible with certain implementations described herein. Certain implementations described herein provide an apparatus200configured to monitor the plurality of layers30of the battery stack layer20(e.g., the relative positions of the edges of the layers30) during manufacturing.

Line scan cameras and laser profilometers have been able to measure alignment of the layers in manufacturing production lines. However, this method is only effective so long as all layers in the battery layer stack20are thin enough to produce reasonable contrast as it relies on wavelength of light near or within the visible portion of the electromagnetic spectrum.

One of the new demands placed on battery performance, especially for electric vehicles, is higher energy densities. One way that battery manufacturers are able to increase energy density is by increasing the thickness of the electrode (e.g., anode; cathode) layers32,34. (See, e.g., J. Billaud et al., “Magnetically Aligned Graphite Electrodes for High-Rate Performance Li-Ion Batteries,” Nature Energy 1, no. 8, p. 16097 (2016).) However, such thickness increases of the anode and the cathode layers32,34can make inline optical and laser methods of measuring layer alignment ineffective.

Certain implementations described herein provide an apparatus and/or a method for measuring battery layer alignment (e.g., electrode layers32,34; separator layers36a,36b) using X-ray imaging. For example, certain implementations described herein can measure a distance between layers30of battery materials before the layers30are rolled or stacked into a final assembly. For another example, certain implementations described herein can track and measure positions of edges of the layers30relative to one another (e.g., the different layers30having different mass densities and different X-ray absorption coefficients). In certain implementations, the apparatus and/or method also allows for measurements of defects in battery layers30, contamination, and layer thickness. Certain implementations described herein provide an apparatus and/or method for measuring battery layer alignment using feedback from X-ray measurements to automatically realign the layers30to increase an assembly yield of the final battery fabrication process.

FIGS.3A-3Dschematically illustrate various example apparatus200in accordance with certain implementations described herein. The apparatus200comprises at least one X-ray source210configured to generate X-rays212with energies that exhibit contrast of transmission through the plurality of layers30of the battery layer stack20. The at least one X-ray source210is configured to face a first side214of the battery layer stack20. The apparatus200further comprises at least one sensor220(e.g., X-ray detector) configured to detect the X-rays212transmitted through the plurality of layers30. The at least one sensor220is configured to face a second side216of the battery layer stack20, the second side216is opposite to the first side214.

For example, the at least one X-ray source210can comprise an X-ray tube and the at least one sensor220can comprise an X-ray detector, the x-ray tube and the X-ray detector located on opposite sides of a location at which the layers30of the battery layer stack20are stacked with one another (e.g., the X-ray detector is below the battery layer stack20and the X-ray tube is above the battery layer stack20). In certain implementations, the at least one X-ray source210and the at least one sensor220are located such that the edges of the layers30of the battery layer stack20, the at least one X-ray source210, and the at least one sensor220are substantially colincar with one another, with the at least one X-ray source210spaced from the edges of the layers30by a first distance in a first direction and the at least one sensor220spaced from the edges of the layers30by a second distance in a second direction substantially opposite to the first direction. Portions of the at least one sensor220can be spaced apart from one another periodically along a lateral direction substantially parallel to the plurality of layers30and in a field of view of the at least one X-ray source210. The relative positions of the edges of the layers30(e.g., the edges of the anode layer32, the cathode layer34, the first separator layer36a, and the second separator layer36b) can be monitored by detecting (e.g., imaging) X-rays212from the at least one X-ray source210that are transmitted through the layers30and received by the at least one sensor220.

Certain implementations described herein provide a method for measuring the spacings between layers30of a battery layer stack20using X-ray absorption contrast imaging. For example, the method can comprise placing the battery layer stack20between at least one X-ray source210and at least one sensor such that some of the X-rays212produced by the at least one X-ray source210pass through the layers30of the battery layer stack20(e.g., the first separator layer36a, the anode layer32, the second separator layer36b, and the cathode layer34) and are detected by the at least one sensor220. The method can further comprise using the at least one sensor220to measure differences in photon counts across a lateral area of the battery layer stack20(e.g., in a plane substantially parallel to the layers30of the battery layer stack20). The X-rays212are absorbed more (e.g., fewer X-rays212are transmitted through) in the portions of the area where there are more layers30present according to the Beer-Lambert Law:

where Iois the number of incident X-rays212, I is the number of transmitted X-rays212, μ is the mass absorption coefficient of the material (which is dependent on the X-ray energy and the atomic element of the material), ρ is the material density of the material, and d is the material thickness (e.g., in a direction substantially perpendicular to the lateral area of the battery layer stack20). Because the materials in one or more of the layers30can contain composite materials, the mass absorption coefficient for the material can be expressed as the sum of the products of the weight percentage, wi, and the mass attenuation coefficient for each element:

To calculate the transmission of the X-rays212through multiple layers30, certain implementations run the calculation for each layer30of the battery layer stack20, where the number of incident X-rays212for each subsequent layer30is the number of X-rays212transmitted through the prior layer30.

To achieve good contrast between layers30(e.g., sufficient contrast to distinguish the different layers30from one another), certain implementations use low energy X-rays212such that each layer30attenuates a significant percentage of the X-rays212(e.g., the at least one X-ray source210can be configured to generate X-rays212having an optimum energy). For example, if one layer30, positioned overhanging another layer30, were to attenuate too many X-rays212, then there would not be enough X-rays212to define contrast between other layers30with any statistical significance. Conversely, if not enough X-rays212are absorbed by the material of the layer30, then the at least one sensor220will not show any significant difference between those layers30. Plastic separator layers36a,bcan be very thin with materials having low atomic weight, so in certain implementations, the low energy the X-rays212are selected to provide sufficient contrast in those layers30.

In certain implementations, the optimum energy of the X-rays212produced by the at least one X-ray source210are calculated by comparing the differences of the transmission of each section of the battery layer stack20. For example,FIG.4schematically illustrates at least one X-ray source210and at least one sensor220on opposite sides214,216of the battery layer stack20(e.g., comprising the cathode layer34, the first separator layer36a, the anode layer32, and the second separator layer36b) in accordance with certain implementations described herein. The X-rays212propagating from the at least one X-ray source210, through the battery layer stack20, to the at least one sensor220are also schematically illustrated by dashed lines. Some of the X-rays212propagate through the cathode layer34, the first separator layer36a, the anode layer32, and the second separator layer36b(denoted as layer group “A”), some of the X-rays212propagate through the first separator layer36a, the anode layer32, and the second separator layer36b(denoted as layer group “B”), some of the X-rays212propagate through the first separator layer36aand the second separator layer36b(denoted as layer group “C”), some of the X-rays212propagate through the second separator layer36b(denoted as layer group “D”), and some of the X-rays212propagate through none of the cathode layer34, the first separator layer36a, the anode layer32, and the second separator layer36b(the empty set denoted by layer group “E”).

FIGS.5A and6Aare example plots of calculated X-ray transmissions from the at least one X-ray source210through the denoted layer groups of the battery layer stack20(e.g., layer group A, B, C, and D) to the at least one sensor220as a function of X-ray energy in accordance with certain implementations described herein. For the calculated X-ray transmissions ofFIG.5A, each of the first and second separator layers36a,bis 50 microns thick, the cathode layer34is 150 microns thick, and the anode layer32is 180 microns thick. For the calculated x-ray transmissions ofFIG.6A, each of the first and second separator layers36a,bis 50 microns thick, the cathode layer34is 8.05 millimeters thick, and the anode layer32is 8.08 millimeters thick.FIGS.5B and6Bare plots of the calculated difference in X-ray transmission between each layer stack forFIGS.5A and6A, respectively, at a range of X-ray energies.FIGS.5C and6Care the same plots asFIGS.5B and6B, respectively, but over a smaller X-ray energy range.

The optimal contrast can be at the x-ray energy where the minimum of all functions is at the greatest magnitude of transmission, which can be represented mathematically as:

In this function, ƒ1(x) to ƒn(x) represent the difference in X-ray transmission between layers30where x is X-ray energy. ƒmin(x) is a function that represents the minimum value for each difference in X-ray transmission for all sections in the battery layer stack20. The X-ray energy where ƒmin(x) is greatest can yield the X-ray energy where contrast between layers30is optimal, which can be represented by the following (e.g., assuming x is the X-ray energy from the at least one X-ray source210that produces the optimal contrast between layers30):

The amount of contrast that is sufficient is dependent on the noise of the system. The difference in mean contrast between two regions divided by the standard deviation can be considered to be the contrast-to-noise ratio. While some of the standard deviation can be the square root of the number of counts due to poisson statistics, the other part of the standard deviation can be a combination of thermal noise, shot noise, and dark current, all of which can be highly dependent on the sensor design. In certain implementations, the amount of contrast considered to be sufficient is determined experimentally.

Because such low energy X-rays212have substantial attenuation from air, certain implementations take into account the air attenuation between the battery layer stack20and the at least one sensor220. For example, the X-ray absorption of air can be calculated using the Beer-Lambert law, where the elemental composition and weight percentages according to documented ratios can be used to determine the mass attenuation coefficient. The density of air at standard temperatures and pressure can be used and the path length is the distance between the window of the at least one X-ray source210and the battery layer stack20plus the distance between the battery layer stack20and the at least one sensor220.

Because the layers30for different battery layer stacks20can have different layer thicknesses and material compositions, certain implementations utilize at least one X-ray source210(e.g., X-ray tube) configured to output a majority of X-rays212at specific X-ray energies (e.g., below 10 keV). For example, X-ray energies can be selected by looking at a table of characteristic X-ray lines and selecting an atomic element with X-ray lines closest to the area where contrast is maximized for the battery layer stack20. While X-ray tubes are polychromatic, their output tapers to zero at the accelerating voltage or kV edge. They also can produce a large number of X-rays212at the characteristic lines of the anode material (e.g., characteristic X-ray lines below 10 keV). Calculating the X-ray tube output can be done by many methods, see, e.g., ‘Pella’, ‘Ebel’, and ‘Finkelshtein and Pavlova’. In certain implementations, however; a first order approximation can be made by calculating the transmission curve of each layer30over an X-ray energy range, then selecting an X-ray tube anode material that has a characteristic X-ray line where each section of the battery layer stack20has an X-ray transmission greater than zero and less than 100%. For example, the X-ray energies can be below 10 keV and configured for imaging layers comprising atomic elements with low atomic numbers (e.g., atomic elements with atomic numbers below 14). As seen inFIG.5C, the X-ray energy where the minimum of all the curves is greatest can be near 4.5 keV, so the at least one X-ray source210can use a titanium anode material having a characteristic X-ray Kα line at 4.51 keV to yield an optimal contrast. If the x-ray energy at which the greatest contrast for the battery layer stack20were around 6.7 keV, then the at least one X-ray source210can use an iron anode material having a characteristic X-ray Kα line at 6.4 keV or can use a cobalt anode material having a characteristic X-ray Kα line at 6.9 keV.FIG.7is a flowchart of an example method300in accordance with certain implementations described herein.FIGS.6A-6Ccorrespond to the flowchart branch beginning with “separate layers into two regions, higher and lower energy.”

In certain implementations in which some regions of the battery layer stack20has a total X-ray transmission close to 100% or 0%, to avoid impractical acquisition times, the at least one X-ray source210can be configured to produce X-rays212having different X-ray energies. For example, an X-ray tube anode can have multiple atomic elements mixed, alloyed, or placed near each other so that the electron beam of the X-ray tube interacts with the multiple atomic elements. For example, tungsten and chromium can be alloyed or placed in proximity to one another at the X-ray tube anode to produce strong characteristic X-ray lines around 10 keV and around 5.8 keV. For another example, molybdenum and copper can be placed in proximity to one another at the X-ray tube anode to produce strong characteristic X-ray lines around 17.5 keV and around 8 keV. A high-powered X-ray tube with a large number of bremsstrahlung X-rays that span the predetermined energy regions for sufficient contrast in the layers can also be used (e.g., a 100 W tungsten anode tube).

In certain implementations, the at least one sensor220is configured to detect the X-rays212transmitted through the battery layer stack20(e.g., X-rays212having X-ray energies in a range of 3 keV to 8 keV). For example, as shown inFIG.3B, the at least one sensor220can comprise at least one one-dimensional (1D) or two-dimensional (2D) pixelated semiconductor sensor222configured to directly detect X-rays212(e.g., silicon-based TDI, CCD, or CMOS-based sensor available commercially from various vendors; 2D pixelated CdTe or CZT sensor). For another example, as shown inFIGS.3C and3D, the at least one sensor220can comprise at least one scintillator224and at least one 1D or 2D pixelated semiconductor sensor222for higher efficiency (see, e.g., M. S. Kim et al., “A comparative study of scintillator combining methods for flat-panel X-ray image sensors,” doi.org/10.1016/j.nima.2017.11.023; E. Durbaric et al., “Resolution and noise properties of scintillator coated X-ray detectors,” Nucl. Instr. And Methods in Phys. Res. A 466, pp. 178-182 (2001)). In certain implementations, the at least one scintillator224can be coupled directly to the at least one semiconductor sensor222(see, e.g.,FIG.3C) or to at least one lens228configured to focus the visible light on the at least one semiconductor sensor222(see, e.g.,FIG.3D). In certain implementations, the at least one X-ray source210(e.g., X-ray tube) is configured to produce incident X-rays212that yield a predetermined contrast between all layers30of the battery layer stack20.

In certain implementations in which multiple X-ray energies are used to get good contrast, multiple scintillators224(e.g., two) can be placed on the same lens228. The thickness of each scintillator224can act as a low pass energy filter for the detected X-rays212(e.g., to allow 90% X-ray transmission at energies above 8 keV). In certain implementations, the at least one scintillator224can comprise at least one attenuator material230comprising one or more materials (e.g., carbon, aluminum, copper, gold) affixed to a top surface of the at least one scintillator224facing the layers30, the one or more materials configured to attenuate at least some of the X-rays212so as to act as a high pass energy filter for incident X-rays212. In certain implementations, an air gap226between the at least one semiconductor sensor222and the at least one scintillator224can also act as a high pass energy filter. By optimizing the thickness of the at least one scintillator224(e.g., low pass energy filter configured to allow 90% X-ray transmission at energies above 8 keV), and the thickness and material type of the at least one attenuator material230(e.g., high pass energy filter), certain implementations comprise at least one notch filter configured such that the at least one scintillator224produces visible light in response to X-rays212within a specific X-ray energy range. Because high energy X-rays212interact with semiconductor materials, the at least one semiconductor sensor222of certain implementations is not placed directly below the lens228. A mirror232can be used to reflect the visible light from the at least one scintillator224by a non-zero angle to the at least one semiconductor sensor222(e.g., reflected by an angle approximately equal to 90 degrees). Analysis of the two different sections on the at least one semiconductor sensor222can yield contrast of different sections of the battery layer stack20.

FIG.8schematically illustrates an example sensor220comprising a dual scintillator224in accordance with certain implementations described herein. The sensor220comprises a first scintillator224ahaving a first thickness and a second scintillator224bhaving a second thickness greater than the first thickness. For example, the first thickness can be optimized for first X-rays212ahaving a first X-ray energy range and the second thickness can be optimized for second X-rays212bhaving a second X-ray energy range greater than the first X-ray energy range. For example, each scintillator224a,bcan have a different thickness configured to absorb a different portion of the X-rays212transmitted through the layers30, the different portions having different X-ray energies. The sensor220further comprises at least one attenuator material230(e.g., low energy filter) on at least one scintillator224of the first and second scintillators224a,b(e.g., the second scintillator224b). The at least one attenuator material230can be configured to substantially block low energy X-rays212from the at least one scintillator224(e.g., the at least one attenuator material230and the at least one scintillator224acting as an energy notch filter).

The sensor220ofFIG.8further comprises at least one pixelated semiconductor sensor222and a visible light optical subsystem240between the first and second scintillators224a,band the at least one pixelated semiconductor sensor222. The optical subsystem240is configured to focus visible light from the dual scintillator224at the at least one pixelated semiconductor sensor222. For example, as seen inFIG.8, the optical subsystem240can comprise at least one lens228(e.g., one or more focus lenses228a,b,c) and a mirror252. The one or more focus lenses228a,b,ccan be configured to be movable (denoted inFIG.8by a double-headed arrow). The one or more focus lenses228a,b,ccan be controllably moved individually, relative to one another and/or together, as a unit to adjust a focus of the optical subsystem240. The mirror252deflects the visible light from the one or more focus lenses228a,b,ctowards the at least one pixelated semiconductor sensor222.

In certain implementations, the at least one sensor220is configured to generate images indicative of the X-rays212transmitted through the battery layer stack20. For example, the at least one X-ray source210can comprise multiple X-ray tubes configured such that the plurality of layers30can be moved between the at least one sensor220and the multiple X-ray tubes such that images generated by the at least one sensor220can be reconstructed as at least one laminographic image. The apparatus200can be configured to analyze the images to generate information about an alignment of the layers30and/or defects and contamination among the layers30. To identify which layer30has the defect (e.g., in the portion of the image where there are multiple layers30), certain implementations utilize multiple sensors220within the cone angle of the at least one X-ray source210. A laminographic 2D depth or 3D reconstruction can be performed in certain implementations using the known battery layer speed as the layers30move past each sensor220and using the time delayed images collected by the multiple sensors220to identify the location of defects, damage, or contamination within the layers30before the battery layer stack20is assembled. In certain implementations, the contrast of the images is calibrated with the same materials of known thickness, and the thickness of the individual layers30can be measured as well.

For example, the apparatus200can comprise a computing device configured to analyze the at least one laminographic image to determine at least one of: a thickness of at least one layer30of the plurality of layers30, a variation of thickness of at least one layer30of the plurality of layers30along a lateral direction substantially parallel to the plurality of layers30, an order and/or positions of the layers30of the plurality of layers30, and/or at least one defect, damage, or contamination of the plurality of layers30. The computing device can be configured to use the information generated by the apparatus200to perform at least one of: monitoring positions of one or more edges of the layers30of the plurality of layers30and identifying defects, damage, and/or contamination computationally or through machine learning algorithms.

The computing device can comprise a processing unit (e.g., microprocessor; application-specific integrated circuits; generalized integrated circuits programmed by software with computer executable instructions; microelectronic circuitry; microcontrollers) executing a software application compatible with certain implementations described herein. The processing unit can comprise or can be in operative communication with storage circuitry to store information (e.g., data; commands) accessed by the processing unit during operation (e.g., while providing the functionality of certain examples described herein). The storage circuitry can comprise a tangible (e.g., non-transitory) computer readable storage medium, examples of which include but are not limited to: read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory. The storage circuitry can be encoded with software (e.g., a downloaded computer program) comprising computer executable instructions for instructing the processing unit (e.g., executable data access logic, evaluation logic, and/or information outputting logic). The processing unit can execute the instructions of the software to provide functionality as described herein. Examples of the computing device include, but are not limited to: notebook computer; laptop computer; smartphone; smart tablet. The computing device can also comprise one or more peripheral devices, examples of which include, but are not limited to: user input or output device; keyboard; mouse; trackball; touchpad; pen; pointer; display device (e.g., image projector); computer memory device. The computing device can also be in operational communication with another computing device (e.g., server) via a network, examples of which include, but are not limited to: the Internet, Ethernet networks, wide area networks (WAN), wireless local area networks (WLAN), wireless fidelity (WiFi) networks, wireless gigabit alliance (WiGig) networks, wireless personal area networks (WPAN).

In certain implementations, the apparatus200is configured to use the measurements outlined herein to provide feedback to battery manufacturers about alignment, defects, damage, or contamination with the layers during fabrication of the battery layer stack. For example, the apparatus200can be configured to use information regarding the measured relative positions of the edges of the layers30to automatically realign misaligned layers30. The apparatus200can use this information (e.g., in real-time during fabrication of the battery layer stack20) to generate feedback signals in response to the information. In certain implementations, the apparatus200transmits the feedback signals to the battery rolling mechanism100to automatically (e.g., without human intervention) and controllably adjust operational aspects of the battery rolling mechanism100(e.g., the plurality of rollers110). The battery rolling mechanism100can be configured to respond to the feedback signals by maintaining alignment of the plurality of layers30to a predetermined degree during fabrication (e.g., sufficiently aligned so that the battery layer stack20can continue to be rolled reliably; to prevent telescoping of the layers30; such that the resultant battery layer stack20performs electrically to predetermined specifications). In certain other implementations, the feedback signals can be configured to pause the battery rolling mechanism100so that human intervention can be initiated to manually align the layers30of the plurality of layers30with one another and/or to remove one or more layers30of the plurality of layers30.

In certain implementations in which the battery layer stack20is configured to be used in pouch batteries, the images can be used to identify the spacing between anode layer32and the cathode layer34while the battery layer stack20is being assembled (e.g., in real-time). For example, an image of the battery layer stack20can be used as a flat field normalization for the next subsequent layer30so that the position of the new layer30can be determined relative to the other layers30that have already been placed. Certain such implementations determine misalignments of the electrode layers32,34while the battery10is being assembled.

In certain implementations, the system can use machine learning algorithms to analyze the images to identify problematic defects, damage or contamination and/or to set limits on when and how to align based on feedback from analysis done after the layers30are assembled into battery layer stacks20. For example, parameters such as defect size, location, alignment variance at various locations during winding can be recorded. Batteries can then be inspected after final assembly using current destructive methods and/or non-destructive methods (e.g., industrial CT), and information can be recorded about the quality and performance of the batteries after assembly. Machine learning algorithms, such as the k-nearest neighbor algorithm, can then be implemented to find relationships between failure modes and data taken during inline inspection. If, for example, batteries having a certain number of defects and variance in alignment tend toward a particular failure mode, then limits can be set production to predict if a battery10will likely pass, will likely fail, or will need further inspection. Certain such implementations can help increase throughput by limiting how many parts need final inspection without sacrificing quality. Certain such implementations can increase throughput and limit unnecessary intervention from the system.

Although commonly used terms are used to describe the systems and methods of certain implementations for ease of understanding, these terms are used herein to have their broadest reasonable interpretations. Although various aspects of the disclosure are described with regard to illustrative examples and implementations, the disclosed examples and implementations should not be construed as limiting. Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain implementations include, while other implementations do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more implementations. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.

Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is to be understood within the context used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain implementations require the presence of at least one of X, at least one of Y, and at least one of Z.

Language of degree, as used herein, such as the terms “approximately,” “about,” “generally,” and “substantially,” represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately,” “about,” “generally,” and “substantially” may refer to an amount that is within ±10% of, within ±5% of, within ±2% of, within ±1% of, or within ±0.1% of the stated amount. As another example, the terms “generally parallel” and “substantially parallel” refer to a value, amount, or characteristic that departs from exactly parallel by ±10 degrees, by ±5 degrees, by ±2 degrees, by ±1 degree, or by ±0.1 degree, and the terms “generally perpendicular” and “substantially perpendicular” refer to a value, amount, or characteristic that departs from exactly perpendicular by ±10 degrees, by ±5 degrees, by ±2 degrees, by ±1 degree, or by ±0.1 degree. The ranges disclosed herein also encompass any and all overlap, sub-ranges, and combinations thereof. Language such as “up to,” “at least,” “greater than,” less than,” “between,” and the like includes the number recited. As used herein, the meaning of “a,” “an,” and “said” includes plural reference unless the context clearly dictates otherwise. While the structures and/or methods are discussed herein in terms of elements labeled by ordinal adjectives (e.g., first, second, etc.), the ordinal adjectives are used merely as labels to distinguish one element from another, and the ordinal adjectives are not used to denote an order of these elements or of their use.

Various configurations have been described above. It is to be appreciated that the implementations disclosed herein are not mutually exclusive and may be combined with one another in various arrangements. Although this invention has been described with reference to these specific configurations, the descriptions are intended to be illustrative of the invention and are not intended to be limiting. Various modifications and applications may occur to those skilled in the art without departing from the true spirit and scope of the invention. Thus, for example, in any method or process disclosed herein, the acts or operations making up the method/process may be performed in any suitable sequence and are not necessarily limited to any particular disclosed sequence. Features or elements from various implementations and examples discussed above may be combined with one another to produce alternative configurations compatible with implementations disclosed herein. Various aspects and advantages of the implementations have been described where appropriate. It is to be understood that not necessarily all such aspects or advantages may be achieved in accordance with any particular implementation. Thus, for example, it should be recognized that the various implementations may be carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other aspects or advantages as may be taught or suggested herein.