System for performing acoustic measurements on a battery - Patents.com

Abstract

Aspects of the present disclosure relate to a test fixture and non-destructive acoustic inspection method for scanning and inspecting batteries and determining and characterizing various physical phenomena in those batteries. In one aspect, a rastering system for non-invasive acoustic inspection of battery cells includes a holder for placing a battery in the system for acoustic inspection, at least one transducer configured to perform acoustic measurements on the battery cells, and a controller configured with inspection parameters for performing the acoustic measurements, the inspection parameters being dynamic and permutable depending on at least one or more of the shape, size, and form factor of the battery cells.

Description

[Technical field]

[0001] This application claims the benefit of priority under U.S.C. 119(e) to U.S. Provisional Patent Application No. 63 / 309,987, entitled “SYSTEMS AND METHODS FOR COLLECTING ACOUSTIC DATA ON BATTERY CELLS TO DETECT DEFECTS,” filed on February 14, 2022, which claims the benefit of priority to U.S. Provisional Patent Application No. 18 / 109,482, entitled “SYSTEMS AND METHODS FOR COLLECTING ACOUSTIC DATA ON BATTERY CELLS TO DETECT DEFECTS,” filed on February 14, 2023, the contents of which are incorporated by reference in their entireties for all purposes.

[0002] This invention was made with United States Federal Government support under Grant No. SBIR1831080 awarded by the National Science Foundation. The United States Federal Government has certain rights in this invention.

[0003] The disclosed aspects relate to acoustic testing of batteries, and more particularly to test fixtures and non-destructive acoustic testing methods for scanning and testing batteries to determine and characterize various physical phenomena in these batteries. [Background technology]

[0004] The demand for battery cell production is increasing due to increasing usage across various industries, e.g., consumer electronics, automotive, clean energy, etc. Efficient and fast battery diagnostic methods are important to improve battery quality, lifespan, and manufacturing process efficiency. For manufacturing and production, reducing costs (e.g., price per kilowatt-hour (kWh)) is an important goal. Production costs and quality can be reduced by optimizing existing processes and / or introducing new technologies. For example, technological advances in the areas of improved monitoring, manufacturing, and diagnostics can result in cost efficiencies by shortening production process times (and thus reducing energy consumption during production), reducing waste due to damaged cells and cell parts, improving quality, etc.

[0005] Batteries come in a variety of sizes and shapes, and there is a large subset of variables and factors that can affect the fidelity of the data obtained for battery testing. [Brief description of the drawings]

[0006] The accompanying drawings are presented to aid in explaining various aspects of the present disclosure and are provided by way of example only and not limitation.

[0007] [Figure 1] 1 illustrates an exemplary system for analyzing a sample using acoustic signal-based analysis according to some aspects of the present disclosure. [Diagram 2] 1 illustrates another exemplary system for analyzing a sample using acoustic signal-based analysis according to some aspects of the present disclosure. [Diagram 3] 1 illustrates an exemplary rastering system for acoustic inspection of rectangular battery cells, in accordance with some aspects of the present disclosure. [Figure 4] 1 illustrates another exemplary rastering system for acoustic inspection of rectangular battery cells, in accordance with some aspects of the present disclosure. [Diagram 5] 1 illustrates an exemplary rastering system for acoustic inspection of cylindrical battery cells, in accordance with some aspects of the present disclosure. [Figure 6] 6 illustrates an example of the system of FIG. 5 in operation for inspection of cylindrical battery cells, according to some embodiments of the present disclosure. [Figure 7] 6 illustrates another example of the system of FIG. 5 for inspection of cylindrical battery cells, according to some embodiments of the present disclosure. [Figure 8] 8 illustrates an example system architecture for enabling operation of the example rastering system of FIGS. 3-7, in accordance with some aspects of the present disclosure. [Figure 9] 1 illustrates an example process for operating a rastering system for acoustic inspection of battery cells in accordance with some aspects of the present disclosure. [Figure 10] 1 illustrates an example computing device architecture of an example computing device in accordance with certain aspects of the present disclosure. Summary of the Invention

[0008] Aspects of the present disclosure relate to a test fixture and non-destructive acoustic inspection method for scanning and inspecting batteries and determining and characterizing various physical phenomena in these batteries.

[0009] In one embodiment, a rastering system for non-invasive acoustic inspection of battery cells includes a holder for positioning a battery cell in the system for acoustic inspection, at least one transducer configured to perform acoustic measurements on the battery cell, and a controller configured with inspection parameters for performing the acoustic measurements, the inspection parameters being dynamic and replaceable depending on at least one or more of a shape, size, and form factor of the battery cell.

[0010] In another aspect, the rastering system is configured for inspection of a cylindrical battery cell, and the battery cell is a cylindrical battery cell.

[0011] In another embodiment, the at least one transducer is configured to move vertically along the curved surface of the battery cell at each rotation angle to transmit and receive acoustic signals through the battery cell.

[0012] In another aspect, at least one transducer is configured to obtain a plurality of acoustic measurements along an axial surface of the battery cell at each rotation angle based on the received acoustic signal.

[0013] In another aspect, the controller is configured to analyze each of the plurality of acoustic measurements to extract acoustic features indicative of physical characteristics of the battery cell at each rotation angle, and generate an aggregate map based on the extracted acoustic features at each rotation angle.

[0014] In another embodiment, the rastering system further includes one or more rollers configured to rotate the battery cell through a predetermined rotation angle until the entire curved surface of the battery cell has been acoustically measured.

[0015] In another embodiment, the at least one transducer is an array of transducers packaged in a cylindrical unit for transmitting and receiving acoustic signals through an axial surface of the battery cell at each predetermined rotational angle.

[0016] In another embodiment, at least one transducer is a roller transducer.

[0017] In another embodiment, after each rotation of the battery cell by the one or more rollers, at least one transducer is configured to take acoustic measurements along an axial surface of the battery cell to obtain a plurality of acoustic measurements.

[0018] In another aspect, the controller is configured to analyze each of the plurality of acoustic measurements to extract an acoustic signature indicative of a physical characteristic of the battery cell at a corresponding rotation angle, and generate an aggregate map based on the extracted acoustic signature at each rotation angle.

[0019] In another embodiment, the controller is configured to output at least one of an analysis result of the plurality of acoustic measurements and an aggregate map.

[0020] In another aspect, the rastering system is configured for inspection of a rectangular battery cell, where the battery cell is a rectangular battery cell.

[0021] In another embodiment, the at least one transducer is configured to perform one or more of single-sided and double-sided measurements of the battery cell.

[0022] In another embodiment, at least one transducer is a roller transducer.

[0023] In another aspect, the battery cell is a planar cell.

[0024] In another aspect, the controller is configured to control movement of at least one transducer in at least one of two directions to take a plurality of discrete acoustic measurements across a surface of the battery cell.

[0025] In another aspect, the controller is configured to analyze a plurality of individual acoustic measurements to extract significant acoustic features indicative of physical properties of the battery cells.

[0026] In another aspect, the controller is configured to generate an aggregate map of the multiple acoustic measurements.

[0027] In another embodiment, the controller is configured to output at least one of the aggregate map and the analysis of the plurality of acoustic measurements.

[0028] In another aspect, the inspection parameters specify a number of ultrasonic tests from among the ultrasonic tests that may be applied to make the acoustic measurements.

[0029] In another embodiment, multiple ultrasonic tests include pulse / echo, pitch catch & through transmit, and beam steering & phased array applications.

[0030] In one embodiment, a non-invasive method of battery testing using acoustic measurements includes transmitting acoustic signals through a battery cell via one or more first transducers, receiving response signals responsive to the acoustic signals at one or more second transducers, and processing the acoustic response signals to extract acoustic features indicative of physical characteristics of the battery cell, wherein a controller is configured with test parameters for performing the acoustic measurements, the test parameters being dynamic and replaceable depending on at least one or more of a shape, size, and form factor of the battery cell. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Particular aspects and embodiments of the present disclosure are provided in the following description and associated drawings. Alternate aspects may be devised without departing from the scope of the present disclosure. Also, well-known elements of the present disclosure will not be described in detail or will be omitted so as not to obscure the relevant details of the present disclosure.

[0032] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects. Likewise, the term "aspects of the invention" does not require that all aspects of the invention include the described feature, advantage or mode of operation.

[0033] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the embodiments of the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, it is understood that the terms "comprises", "comprising", "including" and / or "comprising" as used herein indicate the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0034] Furthermore, many aspects are described in terms of a sequence of operations to be performed, for example, by elements of a computing device. It will be appreciated that the various operations described herein may be performed by specific circuitry (e.g., an application specific integrated circuit (ASIC)), by program instructions executed by one or more processors, or by a combination of both. Also, these sequences of operations described herein may be considered to be entirely embodied in any form of computer readable storage medium having stored thereon a corresponding set of computer instructions that, when executed, cause an associated processor to perform the functions described herein. Thus, the various operations of the present invention may be embodied in many different forms, all of which are contemplated to be within the scope of the claimed subject matter. Also, for each of the aspects described herein, the corresponding form of any such aspect may be described herein, for example, as "logic configured to" perform the described operations.

[0035] The demand for battery cell production is increasing due to the increasing usage across various industries such as consumer electronics, automotive, and clean energy. A non-exclusive application of battery cells is the electric vehicle (EV) industry. According to various market studies, this industry will require massive growth (about 15 times the current capacity) to meet the EV demand by 2030. The cost of battery cell production should decrease by about 40% according to some estimates. Moreover, the evidence shows that EV battery reliability is critical since the human and financial costs of EV recalls due to faulty batteries are huge (more than $3 billion in 2020-2021).

[0036] The battery manufacturing process is not without challenges: for example, the cost of raw materials is rising and issues during manufacturing can result in poor quality battery cells, which can lead to unreliable battery cells being integrated into the respective application, e.g., an EV, and ultimately resulting in the costly failures mentioned above.

[0037] For example, battery defects may result in poor battery cell performance, catastrophic battery (and / or device) failure, etc. Such defects may arise during the manufacturing process or during normal operation of the battery after it is placed in a device. Such defects are difficult to detect because they are generally deep within the battery cells and are not visible from non-invasive imaging methods or are not substantial enough to be detected by electrical testing methods until the defects cause substantial damage / degradation to the battery.

[0038] In some examples, manufacturing defects may include, but are not limited to, creases, wrinkles, or holes in conventional polymer-based separator materials, cracks or breaks in solid ceramic-based separators, dry spots in the cell due to insufficient electrolyte saturation, electrode holes, creases, delamination, or layer misalignment, foreign debris, burrs, metal particle inclusions, tears, creases, and tab defects including poor quality welds, electrode misalignment, electrode holes and creases, delamination of electrode material, among others.

[0039] Operational defects may include, among others, but are not limited to, plating of lithium metal on the anode material (e.g., dendritic growth, etc.), dry spots in the cell due to electrolyte degradation, gas evolution due to electrolyte or other chemical decomposition, etc. All of these defects may cause micro-short circuits in the battery that, if propagated, may lead to premature cell doom, rapid capacity loss, and / or catastrophic failure.

[0040] Currently available methods for investigating defective batteries include x-ray or CT inspection of the cells and dismantling the battery after poor performance, safety hazard, or field failure is flagged.

[0041] In the field of ultrasonic testing, there is a wide application space and a large subset of important input variables that govern the fidelity of ultrasonic measurements. Some of these variables include contact method, transducer frequency and bandwidth, and acoustic test method (thru, pitch-catch, pulse-echo). When considering ultrasonics for battery testing, there is another subset of physical phenomena including cell geometry, form factor (pouch, prismatic, cylindrical), chemical composition, and process conditions that require unique optimization of acoustic test parameters to adequately capture and quantify the phenomena.

[0042] When performing ultrasonic-based testing of batteries, the wide parameter space for test equipment and sample form factors can create challenges with non-routine engineering and design tasks. For example, a subset of ultrasonic test settings may be optimized to view the folded separator in a lithium-ion battery pouch cell, but may not be able to detect electrode inclusions in the same cell. Conversely, observing separator creases may require different ultrasonic settings for prismatic / hard-can cells versus pouch cells. The wide parameter space in ultrasound when it comes to testing batteries may require that the test system be designed to accommodate different transducer types, different test methods can be performed electronically, and / or the test bed can accommodate most common battery form factors.

[0043] Ultrasonic testing is also highly sensitive to external factors. Even the most basic tests can have significantly altered results due to variations in mechanical alignment, contact force, external temperature, pressure, and environment, as well as variations in the ultrasonic coupler used to deliver the ultrasonic pulse from the transducer to the test sample. The robustly designed ultrasonic testing system described herein can overcome all of these challenges to obtain accurate and repeatable results.

[0044] The systems and techniques described herein for detecting defects in batteries may address the above challenges (as well as other challenges). Specifically, the present disclosure relates to a test set-up (raster scanning system(s)) and a non-destructive acoustic inspection method for scanning and inspecting batteries and determining and characterizing various physical phenomena in these batteries. The raster scanning system disclosed herein supports acoustic testing of battery cells of different shapes and forms (e.g., rectangular battery cells, cylindrical battery cells) and can perform single-sided and / or double-sided acoustic measurements of such battery cells.

[0045] This complete raster scanning device allows battery manufacturers to configure acoustic testing using a variety of acoustic methods, including but not limited to through-transmit, pitch-catch, or pulse-echo, swap between different ultrasonic transducers, perform in-situ versus operando measurements, and adjust the test setup to properly optimize for the application of interest. Once the ultrasonic test setup is established, the motion system allows discretized ultrasonic testing to be safely and repeatedly performed over the entire spatial region of the battery at the user's selected resolution and coupling method. The resulting test data is then extracted and processed by a data analysis pipeline, including but not limited to proprietary data analysis techniques developed by Liminal Insights, Inc. of Emeryville, California, to process and extract significant acoustic signatures indicative of the current and / or future physical characteristics of the battery, including techniques described in U.S. Patent No. 17 / 112,756, filed December 4, 2020, the entire contents of which are incorporated herein by reference.

[0046] A description of an exemplary system for performing non-invasive acoustic measurements of battery cells is provided with reference to Figures 1 and 2. The disclosure then provides exemplary embodiments of techniques for detecting, identifying, and / or locating defects in batteries both during and after manufacturing with reference to Figures 3-7. The disclosure then provides exemplary embodiments of simulation of battery defects for use in models for detecting and identifying defects with reference to Figures 8 and 9A-B. The disclosure concludes with a description of an exemplary device and system architecture with reference to Figure 10.

[0047] FIG. 1 illustrates an exemplary system for analyzing a sample using acoustic signal-based analysis according to some embodiments of the present disclosure. The system 100 may include a sample 102. The sample 102 may include a battery cell or a component thereof at any stage of production or manufacturing of the battery cell or individual components. In some examples, the sample 102 may include a battery cell, an electrolyte at various stages of wetting / distribution through the battery cell, one or more electrodes of the battery cell, a thin film, a separator, a cover sheet, a current collector, an electrode slurry, or materials for forming any of the above components at any stage of their manufacture. The system 100 may include a transmitting transducer Tx 104 or other means for transmitting an excitation acoustic signal into the battery cell (e.g., for transmitting one or more pulses of ultrasonic or other acoustic waves, vibrations, resonance measurements, etc. through the battery cell). The system 100 may further include a receiving transducer Rx 106 or other means for receiving / sensing an acoustic signal, which may receive a response signal generated from the signal transmitted by the Tx transducer 104. Any type of known or later developed transducer for transmitting and receiving acoustic signals may be used as the Tx transducer 104. The signal transmitted by the Tx transducer 104 from one side of the sample 102 on which the Tx transducer 104 is located may include an input excitation signal. For example, the reflected signal from the other side of the sample 102 may include an echo signal. It is understood that references to a response signal may include both the input excitation signal and the echo signal. Furthermore, the Tx transducer 104 may be configured to receive the response signal, and similarly, the Rx transducer 106 may be configured to transmit an acoustic signal. Any type of known or later developed transducer for transmitting and receiving acoustic signals may be used as the Rx transducer 106. Thus, although separately indicated as Tx and Rx, the function of these transducers may be for both transmitting and receiving acoustic signals.In various alternatives, and if not specifically shown, one or more Tx transducers and one or more Rx transducers may be located on the same side or wall, or on different (e.g., opposing) sides of the sample 102. Throughout this disclosure, reference may be made to a transducer pair (a transmit transducer and a receive transducer). Transducer Tx 104 and transducer Rx 106 may form a transducer pair.

[0048] The acoustic pulser / receiver 108 may be coupled to the Tx and Rx transducers 104, 106 to control the transmission of acoustic signals (e.g., ultrasonic signals) and to receive response signals. The acoustic pulser / receiver 108 may include a controller 108-1 for adjusting the amplitude, frequency, and / or other signal characteristics of the transmitted signal. The acoustic pulser / receiver 108 may also receive signals from the Rx transducer 106. While in some examples the acoustic pulser / receiver 108 may be configured as a combined unit, in some examples the acoustic pulser for transmitting the excitation signal via the Tx transducer 104 may be a separate unit in communication with the receiver for receiving the signal from the Rx transducer 106. A processor 110 in communication with the acoustic pulser / receiver 108 may be configured to store and analyze the response signal waveforms in accordance with the present disclosure. Although illustrated as a single processor, the processor 110 may include one or more processors, including remote processors, cloud computing infrastructure, etc.

[0049] Although not explicitly shown in FIG. 1, multiple Tx transducers and / or multiple Rx transducers may be positioned at one or more spatial locations across the sample 102. This allows for investigating spatial variations in acoustic signal characteristics across the sample 102. A multiplexer may be configured in communication with the acoustic pulser / receiver 108 to separate and channel the transmitted excitation signal and the received response signal. In some examples, various acoustic couplers (e.g., solid, liquid, or combinations thereof), such as couplers 103 and 105, may be used to establish or improve contact between the Tx and Rx transducers 104, 106 and the sample 102. Additionally, various mounting or fastening mechanisms (e.g., pneumatic, compression, screw, spring, etc.) may be used to establish or improve contact between the Tx and Rx transducers 104, 106 and the sample 102.

[0050]

[0023] Figure 2 illustrates another exemplary system for analyzing a sample using acoustic signal-based analysis according to some embodiments of the present disclosure. In comparison to Figure 1, system 200 of Figure 2 illustrates a system in which multiple pairs of transmit and receive transducers are used to transmit signals through a sample (e.g., a battery cell) under test and perform acoustic signal-based analysis of the sample.

[0051] The system 200 includes a number of transmit Tx transducers 202 (each of which may be the same as the Tx transducer 104 of FIG. 1). An array of four exemplary Tx transducers 202 is shown in FIG. 2, although the disclosure is not limited to four. Any number of transducers may be used (e.g., any number of Tx transducers in the range of 1 to 10, 15, 20, etc.).

[0052] Similarly, the system 200 includes a number of receiving (sensing) Rx transducers 204 (each of which may be the same as the Rx transducer 106 of FIG. 1). Although an array of four exemplary Rx transducers 204 is shown in FIG. 2, the disclosure is not limited to four. Any number of transducers may be used (e.g., any number of Rx transducers ranging from 1 to 10, 15, 20, etc.). Any given Tx transducer 202 and Rx transducer 204 may form a transducer pair (FIG. 2 shows four transducer pairs). FIG. 2 also shows a multiplexer 206 coupled to the array of four Tx transducers 202 and a multiplexer 208 coupled to the array of four Rx transducers 204. As described above, each of the multiplexers 206 and 208 may be configured in communication with the acoustic pulser / receiver 108 to separate and channel the transmitted excitation signal and the received response signal, respectively. In some examples, various acoustic couplers (e.g., solid, liquid, or combinations thereof), such as couplers 203 and 205, may be used to establish or improve contact between the Tx and Rx transducers 202, 204 and the sample 102. Additionally, various mounting or fastening mechanisms (e.g., pneumatic, compression, screws, etc.) may be used to establish or improve contact between the Tx and Rx transducers 202, 204 and the sample 102.

[0053] The spacing between the Tx transducer 202 and the Rx transducer 204 may be uniform and the same. The system 200 also includes additional elements, such as the sample 102, the ultrasonic pulser / receiver 108 (controller 108-1), and the processor 110, each of which may be the same as their corresponding counterparts described above with reference to FIG. 1 and will not be described in detail for the sake of brevity.

[0054] The exemplary systems 100 and 200 may have any shape or form, may be stand-alone systems, may be portable or fixed, and the like.

[0055] With the exemplary systems used for acoustic signal analysis of batteries described with reference to Figures 1 and 2, the present disclosure now moves on to describing various rastering systems that use the features and components of systems 100 and 200 to accommodate acoustic inspection of battery cells having various shapes and sizes.

[0056] FIG. 3 illustrates an exemplary rastering system for acoustic inspection of rectangular battery cells, according to some embodiments of the present disclosure.

[0057] The exemplary structure 300 of FIG. 3 is an image of real-time operation of a system 302 for acoustically measuring a physical characteristic of an exemplary rectangular battery cell 304. Similar to systems 100 and 200 of FIGS. 1 and 2, system 302 may include a transducer(s), such as transducer 306, mounted to a mechanical or electrical actuator, which is mounted to an x- and / or y- and / or z-motion stage. Transducer 306 may be controlled to transmit acoustic signals via multiple locations on battery cell 304. Although not shown in exemplary structure 300, there may be an equivalent receiving transducer on the bottom surface of battery cell 304 to receive a response signal in response to the acoustic signal transmitted via transducer 306.

[0058] In example 300, either the system 302 and / or alternatively the platform on which the battery cell 304 rests can move horizontally in the x and / or y directions for the transducer 306 to scan and measure multiple locations across the battery cell 304. This movement is shown in example 308, where after each instance of measurement, the pair of transducers 306 and 310 "scan" and measure the entire surface of the battery 304 by moving a predetermined distance in the x and / or y directions and taking a measurement (individual / independent measurement) across the battery cell 304.

[0059] An exemplary flow 312 illustrates this process, whereby after each measurement by the receiver transducer 310, the transmitter transducer 306 / system 302 generates an acoustic waveform, which may be processed by various signal processing methods to generate an acoustic metric 314 or multiple acoustic metrics for that particular measurement. The system 302 (and / or alternatively the battery cell 304) then moves a predetermined distance (e.g., 1 mm, 2 mm, etc.) in the x and / or y directions to repeat the measurement at a different location and generate similar acoustic metric(s) 314 at the new location. Once the scan of the battery cell 304 is complete, all acoustic metrics corresponding to the different measurement locations may be aggregated into an acoustic map (metric map) of the entire battery cell 304, such as map 316. The individual acoustic metrics 314 and / or aggregate map 316 may be further processed / analyzed to extract significant features or scores indicative of the physical characteristics of the battery cell 304. Such physical characteristics may include, but are not limited to, state of health, stage of charge, various scores indicative of the current and / or future physical condition and performance of the battery cell 304, and the like. Such scores may include, but are not limited to, wetting scores, solid electrolyte interphase (SEI) formation scores, aging scores, cycle life prediction scores, detection, labeling, location of defects in the battery cell 304, and the like. Various numerical and signal processing techniques that may utilize trained machine learning models may be used to extract and interpret significant acoustic features indicative of the physical characteristics of the battery cell 304. Non-limiting examples of such techniques have been developed by Liminal Insights, Inc. of Emeryville, California, including those described in U.S. Patent Application No. 17 / 112,756, filed December 4, 2020, the entire contents of which are incorporated herein by reference.

[0060] FIG. 4 illustrates another exemplary rastering system for acoustic inspection of rectangular battery cells, according to some embodiments of the present disclosure.

[0061] 4 shows three snapshots A, B, and C of a system, each snapshot being of an example system at a different position as it scans a battery cell 404. The battery cell 404 may be a rectangular / planar cell.

[0062] The transducer 402 may be a roller transducer fixed to the housing / arm 401 and may be made of any known or later developed material and may include mechanical and / or electrical systems and actuators to enable the arm 401 to move the transducer 404 across the battery cells 404 to take acoustic measurements.

[0063] In snapshot A, the transducer 402 is shown above the battery cell 404 and ready to begin scanning the battery cell 404. In snapshot B, the transducer 402 is in contact with the battery cell 404 and rolling across the battery cell 404 to take acoustic measurements. In snapshot C, the transducer 402 is shown completing one sweep / scan of the battery cell 404 at the end (the other edge of the battery cell 404). In this example of FIG. 4, the transducer 402 is performing a single-sided scan of the battery cell 404. In other words, the roller transducer 402 may act as both a transmitter and a receiver of the acoustic signal of the battery cell 404, which may then be processed and analyzed to extract significant acoustic features as described above.

[0064] 3, either the arm 401 / transducer 402 or the battery cell 404 can be moved in the x and / or y directions to allow the roller transducer 402 to scan the entire surface of the battery cell 404. The arm 402 can also move up and down in the z direction to bring the transducer 402 into contact with the battery cell under test, and can also move the transducer 402 away from the battery cell 404 after the sweep / scan is completed.

[0065] In some examples, ultrasonic measurements made by transmit / receive transducers, such as transducers 104 / 106, 202 / 204, 306 / 310, and 402 in Figures 1-4, include, but are not limited to, pulse / echo, pitch catch & through transmit, beam steering & phased array applications. Measurements may be air-coupled, liquid-coupled, and / or solid-contact solution that can be tuned to balance signal-to-noise ratio (SNR) and various test environment tradeoffs. Measurements may be made according to various delay line and beam focusing strategies to detect sub-100 μm defects in battery cells.

[0066] Additionally, the transducers 104 / 106, 202 / 204, 306 / 310, and 402 of Figures 1-4 can be bundled into 1D, 2D, and / or 3D arrays that can be controlled via common and / or individualized actuation systems (described below with reference to Figure 8) to statically or dynamically measure batteries in real-time high-throughput scenarios.

[0067] The double-sided actuation system(s) may be designed to bring single transducers, transducer arrays, and other ultrasonic sensors to a suitable focal distance from the battery cell to be inspected if non-contact inspection is performed, or alternatively, to bring the sensor head(s) into full physical contact with the battery cell to be inspected. The actuation system(s) and their dynamics may be fully adjustable and controllable via one or more controllers as described below with reference to FIG. 8. Variable lateral resolution may be automatically selected and implemented depending on whether the defect / phenomenon of interest is a large bulk defect or a local defect embedded inside a battery cell, such as sample 102 / 202, battery cell 304 / 404, for example. Sample 102 may be a battery cell similar to battery cells 304 and 404.

[0068] Variable lateral resolution can be automatically selected and implemented depending on whether the defect / phenomenon of interest is a large bulk defect or a localized defect buried deep inside the battery cell.

[0069] The exemplary systems of Figures 1-4, and particularly the rastering systems of Figures 3 and 4, can be designed such that the battery cell to be tested can be automatically inserted for testing and then removed, allowing such a system to be fully integrated into a battery production line for fast and non-invasive testing of battery cell components, such as electrodes and separators, battery cells, battery modules, battery packs, etc.

[0070] Additionally, the exemplary systems of Figures 1-4, and particularly the rastering systems of Figures 3 and 4, can utilize an automated rotating carousel architecture to switch between different types of transducers (e.g., between transducers 306 / 310 and roller transducer 402) without having to manually swap transducers for different types of battery cells being inspected.

[0071] FIG. 5 illustrates an exemplary rastering system for acoustic inspection of cylindrical battery cells, according to some embodiments of the present disclosure.

[0072] The exemplary system 500 for inspection of cylindrical battery cells may include a casing 502 made of any known or later developed material. A glass top 504 covers a portion of the system 500 and may include an opening 506 for receiving a cylindrical battery cell to be acoustically inspected. A holding mechanism 508 may be used to hold and / or rotate the cylindrical battery cell to be inspected. This testing is further described below with reference to FIGS. 6 and 7. The system 300 may also include a stage 510 for mounting and mounting transducers for multiple methods of inspecting cylindrical acoustic cells, which are further described below. FIG. 5 further illustrates an exemplary z-translation motor 512. The motor 512 is configured to enable full rotation of the cylindrical battery cell for acoustic inspection with infinite resolution. For example, the motor 512 may control the movement of multiple idlers to rotate the cylindrical battery cell.

[0073] FIG. 6 illustrates an example of the system of FIG. 5 in operation for inspection of cylindrical battery cells, according to some embodiments of the present disclosure.

[0074] The example 600 includes two snapshots A and B of the operation of the system 500 of FIG.

[0075] In snapshot A, cylindrical cell 602 is shown positioned in a holder in system 500 (e.g., through opening 506 in FIG. 5). Two exemplary rollers 604 and 605 (which may also be referred to as idlers or grippers) are shown connected to actuators (mechanical arms) 608A and 608B, respectively. In one example, actuators 608A and 608B may be controlled / operated by motor 512. Snapshot A also shows two roller (cylindrical) transducers 606 and 607, each controlled / driven by actuators 608C and 608D, respectively. Each of transducers 606 and 607 may have a wired controller to a controller (e.g., processor 110 in FIG. 1) via cables 610 and 611. Cable 611 is shown in snapshot B. Each of the transducers 606 and 607 may be an array of transducers packaged into a cylindrical unit for a single instance of transmitting and receiving an acoustic signal at every rotation angle, such that at any given angle, an entire vertical or axial slice of the battery cell 602 (from the top to the bottom of the battery cell 602) may be acoustically measured at that single instance of transmitting and receiving an acoustic signal.

[0076] In snapshot A, rollers 604 and 605 and transducers 606 and 607 are separated from cylindrical cell 602, indicating either that the battery cell 602 has just been placed into system 500 for testing or that testing of battery cell 602 has been completed and it can be removed from system 500.

[0077] In snapshot B, rollers 604 and 605 and transducers 606 and 607 are in contact with cylindrical cell 602. During contact, rollers 604 and 605 may rotate cylindrical cell 602 in theta direction (as shown by 612). With each incremental rotation in theta direction 612, transducers 606 and 607 acoustically inspect cylindrical cell 602 by transmitting and receiving acoustic signals. After each rotational measurement to measure a partial or every theta position from 0° to 360°, battery cell 602 may be translated (moved) some incremental distance in the axial (theta) or z direction. Rotation of cylindrical cell 602 in theta direction 612 continues until the entire axial surface of cylindrical cell 602 has been acoustically scanned.

[0078] FIG. 7 illustrates another example of the system of FIG. 5 for inspection of cylindrical battery cells, according to some embodiments of the present disclosure.

[0079] Image 700 shows an example of a rastering system for acoustic inspection of cylindrical battery cells in operation. Compared to the example of FIG. 6, the cylindrical cell 702 is not held in place and rotated using rollers, but rather mounted in a mechanism that controls the rotation of the cylindrical cell 702 in the theta direction 612 via the bottom surface of the cylindrical cell 702. The cylindrical cell 702 can be rotated in the theta direction 612 at a predetermined rotation angle. For example, the cylindrical cell 702 can be rotated 5 degrees at a time, and at each rotation, it can be acoustically scanned with transducers 704 and 706. The transducers 704 and 706 can be controlled to move up and down in the z direction to scan the cylindrical cell 702 at a given angle to make multiple individual and independent measurements (e.g., slices of the cylindrical cell 702) over the curved surface (axial length) of the cylindrical cell 702. This process continues until the entire axial surface (curved surface) of the cylindrical cell 702 has been acoustically scanned.

[0080] Diagram 710 shows a simplified version of the process for rotating and inspecting cylindrical cell 702 .

[0081] The figure also illustrates the step-by-step construction of an aggregate map of acoustic measurements of the cylindrical cell 702. As described above, at each rotation angle, the transducers 704 and 706 may move up and down to transmit and receive acoustic signals through a strip of vertical positions of the cylindrical cell 702. The results of these acoustic measurements are recorded as shown. For example, the results 720 show acoustic measurements 722 of positions along the vertical surface of the cylindrical cell 702 at angle 0. The cylindrical cell 702 may then be rotated 5 degrees, and another set of acoustic measurements 724 may be obtained and added to the measurements 722 to result in the map 726. This process may continue until the cylindrical cell 702 has been rotated 360 degrees and acoustic measurements have been taken to generate an aggregate map 728. The results shown in the map 728 may be processed and analyzed as described above to extract significant acoustic features indicative of the physical properties of the battery cell 702.

[0082] The non-limiting examples discussed above utilize a combination of rotational propulsion and alignment mechanisms, as described above, to simultaneously clamp and rotate cylindrical cells of any size or length about an axis. Such systems are compatible with, for example, 18650, 2170, and 4680 cylindrical cell form factors, as well as any other existing and / or future developed form factors, sizes, and / or shapes of cylindrical battery cells.

[0083] In these exemplary systems, a transducer, transducer pair, transducer array, or other type of ultrasonic sensor may be moved adjacent to the mechanism in its length axis as the propulsion system moves in the theta direction and then measured at selected points relative to a linear cross section of a battery cell, such as cylindrical cell 702. The result is a fully resolved ultrasonic scan of the cylindrical battery that may be visualized in 2D space as described above with reference to FIG.

[0084] In some instances, the exemplary systems described above with reference to Figures 5-7 are designed so that cylindrical samples can be safely and effectively inserted and removed from the system after testing without the need to manually engage the rotational propulsion and alignment system at the throughput required for battery production.

[0085] FIG. 8 illustrates an example system architecture for enabling operation of the example example rastering system of FIGS. 3-7 in accordance with some aspects of the present disclosure.

[0086] The exemplary architecture 800 relates to a rastering system for inspection of rectangular battery cells (as described with reference to Figures 3 and 4), but may be equally applicable to a rastering system for inspection of cylindrical battery cells.

[0087] As shown, a rectangular battery cell 802 may be arranged in a rastering system having architecture 800. Acoustic measurements may be performed using transducers 804 (transmitting transducer) and 806 (receiving / receiver transducer). Transducers 804 and 806 may be a single transducer, or multiple transducers, or a linear or matrix array of transducers. Combiners 805 and 808 may be the same as combiners 103 / 105 and 203 / 205 described with reference to Figures 1 and 2.

[0088] The architecture 800 may also include actuators 810 and 811 for controlling the movement of the transducers 804 and 806, respectively. The actuators 810 and 811 may be independently or commonly controlled, for example, by a controller 812. The controller 812 may receive commands to control the actuators 810 and 811 from a programmable logic controller (PLC) 814. The PLC 814 may be programmed for testing battery cells in a given manufacturing environment with an emphasis on commonality to accommodate all transducers of different sizes, frequencies, bandwidths, etc., with minimal non-recurring engineering (NRE) costs. For example, the PLC 814 may be programmed to control the operation of the actuators 810 and 811 by controlling the operation of the controller 812 to move the transducers 804 and 806 a predetermined distance relative to the battery cell 802 to be acoustically measured. The PLC 814 may further be programmed to control the systems 816 and 818 to move the battery cell 802 in the x and / or y directions. The movement systems 816 and 818 may alternatively be controlled by the controller 812 .

[0089] The PLC 814 may be programmed via an EASI / PC 820, which may interface with a pulse generator 822 to transmit an acoustic signal 824 (e.g., pulse, pitch, etc.) to the transmitter transducer 804. The EASI / PC 820 may also interface with an oscilloscope 826 to control the reception of a response signal 828 via the receiver transducer 806.

[0090] 9 illustrates an example process for operating a rastering system for acoustic inspection of battery cells according to some aspects of the disclosure. The process of FIG. 9 is described in terms of a controller. The controller may be the PLC 814 of FIG. 8, the controller 812 of FIG. 8, or the processor 110 of FIG. 1 and FIG. 2. It should be noted that such a controller may have computer readable instructions (stored in the controller or in associated memory) that are executed to perform the steps of FIG. 9.

[0091] In step 900, the controller may receive test parameters. The test parameters may include, but are not limited to, specifications for controlling the transmitter and receiver transducers 804 and 806, specifications regarding the movement of the battery cell 802 to be tested (e.g., incremental movement in the x and / or y directions), and the type of acoustic measurement to be made (e.g., pulse / echo, pitch catch-and-through transmission, etc.).

[0092] The specifications may optionally include parameters regarding how often battery cells are automatically placed and removed into the rastering system for testing, specifications regarding ultrasonic test modifications to be utilized, and the like.

[0093] The test parameters may be dynamic and substitutable in the sense that depending on the shape, size, and / or form factor of the battery cell being tested, one or more of the test parameters may be changed to accommodate the shape, size, and / or form factor of such particular battery cell.

[0094] In step 902, the controller may perform an acoustic inspection of the battery cells based on the received inspection parameters.

[0095] In step 904, the controller may generate a visual representation of the acoustic measurements made in step 902. Examples of such measurements may be map 316 of FIG. 3, map 728 of FIG.

[0096] In step 906, the controller may extract significant acoustic features indicative of physical characteristics of the battery cell, battery pack, and / or battery module under test based on an analysis of the acoustic measurements taken, as described above.

[0097] In step 908, the controller may output the results of the analysis in step 906. As described above, the output may be any one or more of a wetting score, a SEI formation score, an aging score, a cycle life prediction score, detection / labeling / location of defects in the battery cell, etc. A variety of numerical and signal processing techniques may be used that may utilize trained machine learning models to extract and interpret significant acoustic features indicative of the physical characteristics of the battery cell 304. Non-limiting examples of such techniques are developed by Liminal Insights, Inc. of Emeryville, California, including those described in U.S. Patent Application No. 17 / 112,756, filed December 4, 2020, the entire contents of which are incorporated herein by reference.

[0098] In another example, the output may include an aggregate map of the acoustic measurements (eg, map 316 or 728) in addition to the results of the analysis performed in step 906.

[0099] 10 illustrates an exemplary computing device architecture of an exemplary computing device according to some aspects of the disclosure. The device architecture 1000 of an exemplary computing device that may be used as various components (e.g., processor 110) of system 100 or 200 implements various techniques described herein. The components of computing device architecture 1000 are shown in electrical communication with each other using connections 1005, such as, for example, a bus. The exemplary computing device architecture 1000 includes a processing unit (CPU or processor) 1010 and computing device connections 1005 that couple various computing device components, including computing device memory 1015, such as, for example, read only memory (ROM) 1020 and random access memory (RAM) 1025, to the processor 1010.

[0100] The computing device architecture 1000 may include a cache of high-speed memory directly connected to the processor 1010, closely connected to the processor 1010, or integrated as part of the processor 1010. The computing device architecture 1000 may copy data from the memory 1015 and / or storage device 1030 to the cache 1012 for quick access by the processor 1010. In this manner, the cache may provide a performance boost that avoids delays while the processor 1010 waits for data. These and other modules may control or be configured to control the processor 1010 to perform various operations. Other computing device memories 1015 may be used as well. The memory 1015 may include multiple different types of memories with different performance characteristics. The processor 1010 may include any general-purpose processor and hardware or software services stored in the storage device 1030 and configured to control the processor 1010 as well as special-purpose processors with software instructions built into the processor design. The processor 1010 may be a self-contained system including multiple cores or processors, buses, memory, controllers, caches, etc. Multi-core processors may be symmetric or asymmetric.

[0101] To enable user interaction with the computing device architecture 1000, the input device 1045 may represent any number of input mechanisms, such as, for example, a microphone for audio, a touch-sensitive screen for gesture or graphic input, a keyboard, a mouse, motion input, voice, etc. The output device 1035 may also be one or more of a number of output mechanisms known to those skilled in the art, such as, for example, a display, a projector, a television, a speaker device, etc. In some examples, a multimodal computing device may enable a user to provide multiple types of input to communicate with the computing device architecture 1000. The communication interface 1040 may generally govern and manage user input and computing device output. Not limited to operation with any particular hardware configuration, the basic features herein may be readily substituted with improved hardware or firmware configurations as they develop.

[0102] The storage device 1030 is a non-volatile memory, and may be a hard disk or other type of computer readable medium capable of storing data accessible by a computer, such as a magnetic cassette, a flash memory card, a solid state memory device, a digital versatile disk, a cartridge, a random access memory (RAM) 1025, a read only memory (ROM) 1020, and hybrids thereof. The storage device 1030 may include software, code, firmware, etc. for controlling the processor 1010. Other hardware or software modules are contemplated. The storage device 1030 may be connected to a computing device connection 1005. In one aspect, a hardware module performing a particular function may include software components stored on a computer readable medium in association with hardware components necessary to perform the function, such as the processor 1010, the connection 1005, the output device 1035, etc.

[0103] The term "computer-readable medium" includes, but is not limited to, portable or non-portable storage devices, optical storage devices, and various other media capable of storing, containing, or transporting instruction(s) and / or data. Computer-readable media may include non-transitory media on which data may be stored and does not include carrier waves and / or transitory electronic signals propagating wirelessly or over wired connections. Examples of non-transitory media may include, but are not limited to, magnetic disks or tapes, optical storage media such as compact disks (CDs) and digital versatile disks (DVDs), flash memory, memory or memory devices. A computer-readable medium may store code and / or machine-executable instructions, which may represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. A code segment may be coupled to another code segment or a hardware circuit by passing and / or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted via any suitable means including memory sharing, message passing, token passing, network transmission, etc.

[0104] In some embodiments, computer readable storage devices, media, and memories may include cables or wireless signals containing bit streams, etc. However, when mentioned, non-transitory computer readable storage media explicitly excludes media such as, for example, energy, carrier signals, electromagnetic waves, and the signals themselves.

[0105] Specific details are provided in the above description to provide a thorough understanding of the embodiments and examples provided herein. However, it will be understood by those skilled in the art that the embodiments may be practiced without these specific details. For clarity of explanation, in some examples, the present technology may be presented as including individual functional blocks comprising devices, device components, steps or routines in a method embodied in software, or a combination of hardware and software. Additional components other than those shown in the figures and / or described herein may be used. For example, circuits, systems, networks, processes, and other components may be shown as components in block diagram form so as not to obscure the embodiments in unnecessary detail. In other examples, well-known circuits, processes, algorithms, structures, and techniques may be shown without unnecessary detail so as to avoid obscuring the embodiments.

[0106] Particular embodiments may be described above as a process or method that is depicted as a flowchart, a flow diagram, a data flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe operations as a sequential process, many of the operations may occur in parallel or simultaneously. Also, the order of operations may be rearranged. A process terminates when an operation is completed, but may have additional steps not included in the diagram. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc. When a process corresponds to a function, its termination may correspond to a return of the function to the calling function or to a main function.

[0107] The processes and methods according to the above-described examples may be implemented using computer-executable instructions stored on or otherwise available from a computer-readable medium. Such instructions may include, for example, instructions and data that cause or otherwise configure a general-purpose computer, special-purpose computer, or processing device to perform a particular function or group of functions. Some of the computer resources used may be accessible over a network. The computer-executable instructions may be, for example, binaries, intermediate format instructions such as assembly language, firmware, source code. Examples of computer-readable media that may be used to store instructions, information used, and / or information generated during the methods according to the described examples include magnetic or optical disks, flash memory, USB devices provided with non-volatile memory, networked storage devices, and the like.

[0108] A device implementing the processes and methods according to these disclosures may include hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof, and may take any of a variety of form factors. When implemented in software, firmware, middleware, or microcode, the program code or code segments (e.g., computer program product) to perform the necessary tasks may be stored on a computer-readable or machine-readable medium. A processor(s) may perform the necessary tasks. Typical examples of form factors include laptops, smartphones, mobile phones, tablet devices or other small form factor personal computers, personal digital assistants, rack-mounted devices, standalone devices, etc. The functionality described herein may be embodied in a peripheral device or an add-in card. Such functionality may be implemented on a circuit board among different chips or different processes running on a single device, as further examples.

[0109] The instructions, media for carrying such instructions, computing resources for executing them, and other structures for supporting such computing resources are exemplary means for providing the functionality described in this disclosure.

[0110] In the above description, aspects of the present application are described with reference to specific embodiments, but those skilled in the art will recognize that the present application is not limited thereto. Thus, while exemplary embodiments of the present application have been described in detail herein, it is understood that the inventive concepts may be embodied and utilized in various other ways, and that the appended claims are intended to be construed to include such variations, except as limited by the prior art. The various features and aspects of the present application described above may be used individually or in conjunction. Moreover, the embodiments may be utilized in any number of environments and applications other than those described herein without departing from the broad spirit and scope of the present specification. Thus, the present specification and drawings should be regarded as illustrative and not restrictive. For purposes of illustration, the methods have been described in a particular order. It should be recognized that in alternative embodiments, the methods may be performed in an order different from that described.

[0111] Those skilled in the art will understand that the less than ("<") and more than (">") symbols or terms used herein may be replaced with the less than or equal to ("≦") and more than or equal to ("≧") symbols, respectively, without departing from the scope of the present specification.

[0112] When a component is described as being "configured" to perform a particular operation, such configuration may be achieved, for example, by designing electronic circuitry or other hardware to perform the operation, by programming a programmable electronic circuitry (e.g., a microprocessor or other suitable electronic circuitry) to perform the operation, or any combination thereof.

[0113] The term "coupled" refers to any component that is directly or indirectly physically connected to another component and / or that is in direct or indirect communication with another component (e.g., connected to the other component via a wired or wireless connection and / or other suitable communications interface).

[0114] Although the above disclosure illustrates exemplary embodiments of the present invention, it should be noted that various changes and modifications may be made herein without departing from the scope of the present invention as defined by the appended claims. The functions, steps, and / or actions of the method claims according to the embodiments of the present invention described herein need not be performed in any particular order. Furthermore, although elements of the present invention may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.

[0115] Claim language or other language reciting "at least one" of a set and / or "one or more" of a set indicates that one member of the set or multiple members of the set (in any combination) satisfy the claim. For example, claim language reciting "at least one of A and B" or "at least one of A or B" means A, B, or A and B. In another example, claim language reciting "at least one of A, B, and C" or "at least one of A, B, or C" means A, B, C, or A and B, or A and C, or B and C, or A and B and C. The language of "at least one" of a set and / or "one or more" of a set does not limit the set to the items listed in the set. For example, claim language reciting "at least one of A and B" or "at least one of A or B" may mean A, B, or A and B, and may further include items not listed in the set of A and B.

Claims

1. 1. A rastering system for non-invasive acoustic inspection of battery cells, comprising: a holder for placing a battery cell within the system for the acoustic testing; at least one transducer configured to perform acoustic measurements on the battery cell; a controller configured with test parameters for performing the acoustic measurements, the test parameters being dynamic and replaceable depending on at least one or more of a shape, a size, and a form factor of the battery cell; A rastering system comprising:

2. The rastering system of claim 1 , wherein the rastering system is configured for inspection of cylindrical battery cells, and the battery cells are cylindrical battery cells.

3. The rastering system of claim 2 , wherein the at least one transducer is configured to move vertically along a curved surface of the battery cell at each rotation angle to transmit and receive acoustic signals through the battery cell.

4. The rastering system of claim 3 , wherein the at least one transducer is configured to obtain a plurality of acoustic measurements along an axial surface of the battery cell at each rotation angle based on the received acoustic signal.

5. The controller: analyzing each of the plurality of acoustic measurements to extract an acoustic signature indicative of a physical characteristic of the battery cell at each rotation angle; Generate an aggregate map based on the acoustic features extracted at each rotation angle The rastering system of claim 4 configured to:

6. One or more rollers configured to rotate the battery cell through a predetermined rotation angle until the entire curved surface of the battery cell is acoustically measured. The rastering system of claim 2 further comprising:

7. 7. The rastering system of claim 6, wherein the at least one transducer is an array of transducers packaged in a cylindrical unit for transmitting and receiving acoustic signals through an axial surface of the battery cell at each predetermined rotational angle.

8. 7. The rastering system of claim 6, wherein after each rotation of the battery cell by the one or more rollers, the at least one transducer is configured to take acoustic measurements along an axial surface of the battery cell to obtain a plurality of acoustic measurements.

9. The controller: analyzing each of the plurality of acoustic measurements to extract an acoustic signature indicative of a physical characteristic of the battery cell at a corresponding rotation angle; Generate an aggregate map based on the acoustic features extracted at each rotation angle The rastering system of claim 8 configured to:

10. The rastering system of claim 9 , wherein the controller is configured to output at least one of an analysis result of the plurality of acoustic measurements and the aggregate map.

11. The rastering system of claim 1 , wherein the rastering system is configured for inspection of rectangular battery cells, and the battery cells are rectangular battery cells.

12. The rastering system of claim 10 , wherein the at least one transducer is configured to perform one or more of single-sided and double-sided measurements of the battery cell.

13. The rastering system of claim 12 , wherein the at least one transducer is a roller transducer.

14. The rastering system of claim 11 , wherein the battery cell is a planar cell.

15. 12. The rastering system of claim 11, wherein the controller is configured to control movement of the at least one transducer in at least one of two directions to take a plurality of discrete acoustic measurements across a surface of the battery cell.

16. The rastering system of claim 15 , wherein the controller is configured to analyze a plurality of individual acoustic measurements to extract significant acoustic features indicative of physical properties of the battery cells.

17. The rastering system of claim 16 , wherein the controller is configured to generate an aggregate map of the plurality of acoustic measurements.

18. The rastering system of claim 17 , wherein the controller is configured to output at least one of the aggregate map and an analysis result of the plurality of acoustic measurements.

19. The rastering system of claim 1 , wherein the inspection parameters specify a plurality of ultrasonic tests from among ultrasonic tests that may be applied to make the acoustic measurements.

20. 20. The rastering system of claim 19, wherein the multiple ultrasonic tests include pulse / echo, pitch catch & through transmit, and beam steering & phased array applications.

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