Straight-through transmission eddy current system for on-line inspection of power supply electrodes

Abstract

An eddy current non-destructive evaluation system for an electrode membrane material includes: at least one control module configured to generate a transmission signal; and a first pair of coils. The first coil pair includes: a first coil disposed adjacent to the electrode film material and configured to operate in a transmission mode and generate an electromagnetic field through the electrode film material based on the transmission signal; and a second coil disposed adjacent to the electrode film material and disposed on a side of the electrode film material opposite to the first coil, and configured to operate in a receiving mode. The second coil is configured to generate an electromagnetic field voltage based on the electromagnetic field. The at least one control module is configured to at least one of determine a thickness of the electrode film material and detect a defect of the electrode film material based on the electromagnetic field voltage.

Description

[0001] introduction The information provided in this section is for the purpose of generally presenting the context of the present disclosure. The work of the presently named inventors, to the extent it is described in this section, and aspects of this description that may not otherwise qualify as prior art at the time of filing are neither explicitly nor implicitly admitted to be prior art against the present disclosure. Technical Field

[0002] The present disclosure relates to a system for detecting and correcting electrode characteristics during manufacturing. Background Art

[0003] Conventional vehicles that include an internal combustion engine (ICE) also include a low voltage (e.g., 12V) battery. The low voltage (LV) battery is used to start the ICE and to power various loads in the vehicle. The LV battery is charged via an alternator that converts mechanical energy from the ICE into electrical energy to charge the LV battery.

[0004] Electric vehicles (such as all-electric vehicles, battery electric vehicles (BEVs), and hybrid vehicles including plug-in hybrid vehicles (PHEVs)) include a high voltage (HV) battery pack and a LV battery. The HV battery pack provides power to the HV direct current (DC) load and the auxiliary power module, which converts the high voltage to a low voltage to charge the low voltage (LV) power source (or battery). The LV battery is used to power the LV DC load. The HV load may include a motor for propulsion purposes and other HV loads. The LV load may include, for example, lights, window and seat motors, door locks, infotainment system equipment, etc. The HV battery pack may have terminals at, for example, 400V or 800V. The LV battery may have terminals at, for example, 12V or 48V. When the electric vehicle is started, the LV battery may be used to close the HV contactor to allow power from the HV battery pack to be supplied to the motor and other HV loads. Summary of the invention

[0005] A non-destructive evaluation system for eddy current of electrode film materials is disclosed. The system includes: at least one control module configured to generate a transmission signal; and a first coil pair. The first coil pair includes: a first coil, which is arranged adjacent to the electrode film material and is configured to operate in a transmission mode and generate an electromagnetic field passing through the electrode film material based on the transmission signal; and a second coil, which is arranged adjacent to the electrode film material and is arranged on a side of the electrode film material opposite to the first coil, and is configured to operate in a receiving mode. The second coil is configured to generate a first electromagnetic field voltage based on the electromagnetic field. At least one control module is configured to perform at least one of the following operations based on the first electromagnetic field voltage: determining a first thickness of the electrode film material and detecting defects of the electrode film material.

[0006] In other features, at least one control module is configured to operate the first coil in a receive mode and the second coil in a transmit mode such that the first coil generates a second electromagnetic field voltage, and determine the first thickness based on the second electromagnetic field voltage.

[0007] In other features, at least one control module is configured to: i) determine a first complex transmission coefficient based on the first electromagnetic field voltage, ii) determine a second complex transmission coefficient based on the second electromagnetic field voltage, iii) average the first complex transmission coefficient and the second complex transmission coefficient, and iv) determine the first thickness based on the average.

[0008] In other features, the system further includes a switching circuit connected between i) at least one control module and ii) the first coil and the second coil, wherein the at least one control module is configured to control the switching circuit to transition operation of the first coil and the second coil between operating in a transmission mode and a reception mode.

[0009] In other features, the system further includes an amplifier configured to generate a drive signal based on the transmission signal to drive the first coil and generate a reference signal proportional to the drive signal. The at least one control module is configured to determine the first thickness based on the reference signal.

[0010] In other features, the system amplifier includes: a first multiplier configured to downconvert the reference signal into a downconverted reference signal; and a second multiplier configured to downconvert the received signal into a downconverted received signal. The second coil generates the received signal including the first electromagnetic field voltage. At least one control module is configured to determine the first thickness based on the downconverted reference signal and the downconverted received signal.

[0011] In other features, the transmission signal comprises a plurality of frequencies.

[0012] In other features, the system further includes: a second coil pair, including a third coil and a fourth coil; and a multiplexer. The third coil is arranged adjacent to the electrode film material, and is configured to operate in a transmission mode and generate an electromagnetic field passing through the electrode film material based on a transmission signal. The fourth coil is arranged adjacent to the electrode film material and is arranged on a side of the electrode film material opposite to the third coil, and is configured to operate in a receiving mode, wherein the fourth coil is configured to generate a second electromagnetic field voltage based on the electromagnetic field generated by the third coil. The first multiplexer is configured to select between the second coil and the fourth coil. At least one control module is configured to control the state of the first multiplexer, and to determine the second thickness based on the second electromagnetic field voltage.

[0013] In other features, the system further includes: a first amplifier configured to generate a first drive signal based on the transmission signal to drive the first coil, and output a first reference signal based on the first drive signal; a second amplifier configured to generate a second drive signal based on the transmission signal to drive the third coil, and output a second reference signal based on the second drive signal; and a second multiplexer configured to select between the first amplifier and the second amplifier. At least one control module is configured to control the state of the second multiplexer, determine the first thickness based on the first reference signal, and determine the second thickness based on the second reference signal.

[0014] In other features, the system further includes at least one of a capacitive sensor and a laser vibrometer configured to determine a lift-off distance between the electrode film material and one of the first coil and the second coil. The at least one control module is configured to adjust the first thickness based on the lift-off distance.

[0015] In other features, the at least one control module is configured to operate the first coil to determine a peel distance between the electrode film material and one of the first coil and the second coil, and to adjust the first thickness based on the peel distance.

[0016] In other features, a method for eddy current non-destructive evaluation of electrode film materials is disclosed. The method includes: generating a transmission signal; operating a first coil in a transmission mode and generating an electromagnetic field through the electrode film material based on the transmission signal, the first coil being disposed adjacent to the electrode film material; operating a second coil in a receiving mode and generating a first electromagnetic field voltage based on the electromagnetic field, the second coil being disposed adjacent to the electrode film material and disposed on a side of the electrode film material opposite to the first coil; and performing at least one of the following operations based on the first electromagnetic field voltage: determining a first thickness of the electrode film material and detecting defects of the electrode film material.

[0017] In other features, the method further includes operating the first coil in a receive mode and operating the second coil in a transmit mode such that the first coil generates a second electromagnetic field voltage; and determining the first thickness based on the second electromagnetic field voltage.

[0018] In other features, the method further includes determining a first complex transmission coefficient based on the first electromagnetic field voltage; determining a second complex transmission coefficient based on the second electromagnetic field voltage; averaging the first complex transmission coefficient and the second complex transmission coefficient; and determining the first thickness based on the average.

[0019] In other features, the method further includes: generating a drive signal to drive the first coil based on the transmission signal, and generating a reference signal proportional to the drive signal; and determining the first thickness based on the reference signal.

[0020] In other features, the method further includes: down-converting the reference signal into a down-converted reference signal; down-converting the received signal into a down-converted received signal; generating a received signal including a first electromagnetic field voltage via a second coil; and determining the first thickness based on the down-converted reference signal and the down-converted received signal.

[0021] In other features, the transmission signal comprises a plurality of frequencies.

[0022] In other features, the method further includes: operating a third coil in a transmission mode and generating an electromagnetic field passing through the electrode film material based on a transmission signal, the third coil being disposed adjacent to the electrode film material; operating a fourth coil in a reception mode and generating a second electromagnetic field voltage based on the electromagnetic field generated by the third coil, the fourth coil being disposed adjacent to the electrode film material and disposed on a side of the electrode film material opposite to the third coil; and determining a second thickness based on the second electromagnetic field voltage.

[0023] In other features, the method further includes: generating a first drive signal based on the transmission signal to drive the first coil, and outputting a first reference signal based on the first drive signal; generating a second drive signal based on the transmission signal to drive the third coil, and outputting a second reference signal based on the second drive signal; determining the first thickness based on the first reference signal; and determining the second thickness based on the second reference signal.

[0024] In other features, the method further includes: determining a peel distance between the electrode film material and one of the first coil and the second coil; and adjusting the first thickness based on the peel distance.

[0025] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings.The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present disclosure will become more fully understood from the detailed description and accompanying drawings, in which: Figure 1 is a perspective view of a manufacturing system for performing roll-to-roll processing utilizing eddy current nondestructive evaluation (NDE) of electrode film materials according to the present disclosure; Figure 2 is a diagram illustrating eddy current NDE with feedback and feedforward compensation according to the present disclosure; and Figure 3 is an example plot of electromagnetic field (EMF) voltage versus thickness of electrode film material; Figure 4 is an example plot of normalized change in EMF voltage versus vertical position of electrode film material relative to a center point between EMF coils according to the present disclosure; Figure 5 is an example plot of normalized change in EMF voltage versus vertical position for Stage 1, Stage 2, and combined eddy current monitoring in accordance with the present disclosure; Figure 6 is a top view of an electrode film material according to the present disclosure and a non-staggered array of electromagnetic coil pairs arranged in parallel rows and columns; Figure 7 is a top view of an electrode film material according to the present disclosure and a staggered array of electromagnetic coil pairs arranged in parallel rows and offset columns; Figure 8 is a schematic diagram of a dual-stage eddy current NDE circuit configured for a coil pair according to the present disclosure; Fig. 9 is a schematic diagram of an eddy current NDE circuit configured for an array of coil pairs according to the present disclosure; Fig.10 is a side view of a coil pair for eddy current NDE of electrode film materials and a capacitive sensor for accounting for high peeling according to the present disclosure; Fig.11 According to the present disclosure Fig.10 A top perspective view of a coil pair and electrode film material; Fig.12 According to the present disclosure Figures 10 to 11 A side cross-sectional view of a capacitive sensor; Fig.13 is a side view of a coil pair for eddy current NDE of electrode film materials and a laser vibrometer for accounting for high lift-off according to the present disclosure; Fig.14 is a plot of phase of impedance versus frequency according to the present disclosure; Fig.15is a polar plot of attenuation versus signal frequency change for two different electrode film material thicknesses according to the present disclosure; and Fig.16A and 16B (collectively, FIG. 16 ) illustrates an eddy current NDE method according to the present disclosure.

[0027] In the drawings, reference numerals may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION

[0028] The electrical power source of a vehicle (such as LV and HV batteries and battery packs) includes electrodes, referred to as cathodes and anodes. As an example, the anode may include lithium. Lithium metal has a higher capacity than graphite. For example, 5 micrometers (μm) of lithium metal provides the same 1 milliampere hour per square centimeter (1 mAh / cm2) as 20 μm of graphite. 2 ) capacity. The battery may include a thick lithium metal anode (eg, greater than 20 μm).

[0029] A lithium metal anode can be formed by applying a layer of lithium material to a layer of copper material to form a laminate and cold rolling (or calendering) the laminate between a pair of rollers. The pressure applied by the rollers to compress the laminate can be adjusted. The pressure applied to the laminate affects the final thickness of the laminate. The thickness is directly related to the capacity of the electrode formed. In addition to thickness, surface defects, internal defects, and surface roughness of the laminate may also affect the capacity of the electrode formed.

[0030] Destructive, offline and / or contact-based methods can be used to detect the thickness and thickness variation of the electrode stack. Destructive, offline and / or contact-based methods can include the use of microscopes, physical contact-based meters, etc. However, these methods are invasive, slow, expensive, and cannot provide feedback in real time.

[0031] Examples described herein include eddy current NDE systems and methods for quickly and accurately detecting the thickness of an electrode (or electrode film material) before and after calendering of the electrode (or electrode film material). The method further includes detecting defects in the electrode (or electrode film material), such as electrode film material properties that affect impedance, such as changes in the porosity of the film material, large voids in the film material, and / or other defects (such as agglomeration) that cause non-uniform conductivity. The method is a robust, low-cost, high-speed, and non-contact method. The eddy current NDE system includes a first one or more coils that generate a corresponding electromagnetic field (or alternating current (AC) magnetic field). The first one or more coils are located on a first side of the electrode film material. The electromagnetic field generates an EMF voltage in a second one or more coils on a second side of the electrode film material. The second side is opposite to the first side. The EMF voltage indicates an impedance difference, which indicates a difference in thickness and other characteristics of the electrode film material. This embodiment and other embodiments are further described below.

[0032] The eddy current NDE system is a through-transmission system because the electromagnetic field passes through the electrode film material. The eddy current NDE system enables high line speeds (e.g., greater than 100 meters per minute m / min). High line speed refers to the speed at which the electrode film material moves across the rollers of the manufacturing system and between the rollers. The thickness and defects of the material can be detected at any point along the manufacturing system. In one embodiment, the thickness is detected roll-to-roll (i.e., along the path between consecutive rollers). The method disclosed herein enables accurate measurement of the thickness and thickness uniformity of the electrode film material over a wide range of thicknesses (e.g., within 1 μm accuracy). The system disclosed herein can also be used to detect surface and internal defects of the electrode film material.

[0033] In some disclosed examples, an eddy current NDE system configured for dual phase measurement is provided. In one embodiment, a transmission switch is performed where i) during a first time period, a first one or more coils operate as a transmitter and a second one or more coils operate as a receiver, and then ii) during a second time period, the second one or more coils operate as a transmitter and the first one or more coils operate as a receiver. The EMF voltage generated by the receiver during the first time period is averaged with the EMF voltage generated by the other receiver during the second time period. The thickness is then determined based on the average value. Averaging reduces measurement errors due to vertical vibrations. During movement of the electrode film material on the drum, the vertical positioning of the material may change due to vibrations of the material. The dual phase measurement significantly reduces measurement errors by averaging the EMF voltages of these phases, as further described below. Averaging can be implemented using hardware and / or software.

[0034] Also disclosed herein is real-time peel compensation. Peel refers to the distance between a coil and adjacent electrode film material. When the distance between the electrode film material and adjacent coils varies, these distances are taken into account to provide an accurate measurement of the thickness of the electrode film material, as further described below.

[0035] The examples disclosed herein are applicable to detecting the thickness of cathodes, anodes and layers thereof, such as the thickness of current collectors. These examples are applicable to electrodes and / or electrode layers formed of lithium, copper, sodium, silicon, graphite, aluminum and / or other electrode materials.

[0036] Figure 1 A manufacturing system 100 is shown for performing roll-to-roll processing utilizing eddy current NDE of an electrode film material 102. The manufacturing system 100 includes a first roller 104 having an electrode film material 102 that is fed between two calendering rollers 106, 108 to a second roller 110. The calendering rollers 106, 108 apply pressure to the electrode film material 102 to compress the electrode film material 102. Various rollers may be included to direct the electrode film material from the first roller 104 to the calendering rollers 106, 108 and from the calendering rollers 106, 108 to the second roller 110. A coil pair including a first coil 112 and a second coil 114 is shown on opposite sides of the electrode film material 102. The coils 112, 114 are used to perform the eddy current NDE described herein. Figure 8 An example circuit for powering and controlling the operation and timing of coils 112, 114 is shown in FIG. Figure 1 A single coil pair is shown, but any number of pairs may be included and arranged in various patterns. An array of coils may be included, such as with respect to at least Figure 6 , 7 and 9 as further described.

[0037] Figure 2A diagram 200 illustrating eddy current NDE with feedback and feedforward compensation is shown. The diagram 200 includes material rollers 202, 204 including respective materials. As an example, the roller 202 may include a first material 206 such as lithium metal, and the second roller 204 may include a second material 208 such as copper. The first material 206 and the second material 208 are fed between first calendaring rollers 210, 212 to form a stack, which is compressed by the rollers 210, 212. The first calendaring (or laminating) rollers 210, 212 apply a laminating pressure on the stack 214. The compressed stack 214 is fed between two coils 216, 218, and then fed between second calendaring (or cold rolling) rollers 220, 222. The first calendaring rollers 210, 212 are used during a first compression stage 230. The first compression stage is a pre-NDE processing stage. The coils 216, 218 are used during the intermediate evaluation stage 232. The second calendering rollers 210, 212 are used during the second compression stage 234 to apply calendering pressure on the stack 214. The second compression stage is a post-NDE processing stage.

[0038] Feedback control (or adjustment) of the first compression stage 230 may be performed based on eddy current NDE performed using coils 216, 218. This may include, for example, adjusting the pressure applied to the stack 214 by the first calendering rollers 210, 212 based on the detected thickness of the compressed stack 214. This may be accomplished via an actuator and motor 231, which may be driven by, for example, Figures 8 to 9 If the thickness is greater than the target thickness (or thickness range), then more pressure may be applied. Similarly, if the thickness is less than the target thickness (or thickness range), then less pressure may be applied. Feed-forward control (or adjustment) may be performed based on eddy current NDE performed using coils 216, 218. This may include, for example, compressing the stack 214 a second time and adjusting the pressure applied by the second calendering rollers 220, 222. This may be accomplished via an actuator and motor 233, which may be provided by, for example, Figures 8 to 9 234 . As another example, certain materials having thicknesses outside of a target range may be discarded and / or not used to form an electrode. Although a single coil pair is shown between stages 230, 234, an additional coil pair may be included after the second calendering rollers 220, 222 to detect the thickness of the stack 214 after the second compression stage 234. In one embodiment, if the thickness detected at stage 232 indicates a thickness greater than a target thickness (or thickness range), the stack 214 is compressed a second time. The pressure applied at 234 may be greater than the pressure applied at 230.

[0039] The lamination speed at which the first material 206 is applied to the second material 208 can also be adjusted based on the detected thickness, which is the speed at which the stack 214 moves through the system and is compressed. This can be done via the actuators and motors 231, 233 and / or other actuators and motors. For example, if the thickness is less than the target thickness (or thickness range), the speed can be increased. If the thickness is greater than the target thickness (or thickness range), the speed can be decreased.

[0040] The position of the first calendering rollers 210, 212 can also be adjusted based on the detected thickness via the actuator and motor 231. If the thickness is greater than the target thickness (or thickness range), the first calendering rollers 210, 212 are moved closer to each other. One of the rollers 210, 212 can be moved closer to the other of the rollers 210, 212. If the thickness is less than the target thickness (or thickness range), the first calendering rollers 210, 212 are moved away from each other. One of the rollers 210, 212 can be moved away from the other of the rollers 210, 212. This can be similarly performed during feed-forward control to adjust the distance between the rollers 220, 222 via the actuator and motor 233. The surfaces of the rollers 220, 222 can be adjusted to smooth out the first material 206 in the stack 214.

[0041] Figure 3 A plot of EMF voltage versus thickness of electrode film material is shown. As an example, if a current is supplied to Figure 1 If the first coil 112 is energized, then an EMF voltage is generated in the second coil 114, which can be detected. The EMF voltage depends on the thickness of the electrode film material 102. As shown in the plot, as the thickness increases, the EMF voltage decreases, and vice versa. The eddy current NDE method described herein is based on the transmission of a high frequency magnetic field that generates an EMF voltage. The plot is shown as an example when there is no vibration and the relative distance change (or vertical deflection) of the electrode film material is 0 (i.e., the distance between the coils 112, 114 and the electrode film material 102 does not change).

[0042] Figure 4 A plot showing the normalized change in EMF voltage versus the vertical position of the electrode film material relative to the center point between the EMF coils is shown. The 0Z position of the plot refers to when Figure 1The electrode film material 102 is "centered" and therefore equidistant from the first coil 112 and the second coil 114. As the electrode film material 102 moves closer to the first (or transmitting) coil 112, the change in normalized EMF voltage decreases. As the electrode film material 102 moves closer to the second (or receiving) coil 114, the change in normalized EMF voltage increases.

[0043] The vibration of the sample (or electrode film material 102) introduces systematic errors that cannot be filtered out using software. The examples disclosed herein include performing a two-stage measurement routine, which includes transmitting a signal via the first coil 112 during the first stage (stage 1) and generating a first EMF voltage at the second coil 114. During the transition phase, the roles of the coils 112, 114 are switched. During the second stage (stage 2), the second coil 114 operates as a transmitting coil and transmits a signal, while the first coil 112 operates as a receiving coil and outputs a second EMF voltage. The switching requires a predetermined time period (e.g., 4 μs). As an example, each stage in the first stage and the second stage can last 8 μs. Because each stage is so short and the switching between the stages occurs so quickly, the electrode film material is sensed by the system as being stationary (not vibrating) even if the electrode film material is vibrating. This allows: i) the system to accurately detect thickness regardless of whether the electrode film material is vibrating (or moving vertically), and ii) high line speeds of the drum (e.g. 100 m / min), since for such high line speeds the sample only travels 33 μm during a measurement window of 20 μs.

[0044] Figure 5 A plot of normalized change in EMF voltage versus vertical position for phase 1, phase 2, and combined eddy current monitoring is shown. A first curve 500 represents phase 1. A second curve 502 represents phase 2. A third curve 504 represents the combination and averaging of the outputs provided during phase 1 and phase 2. Combining the results from phase 1 and phase 2 can significantly reduce systematic errors due to motion in the z direction (e.g., due to vibration). In the example shown, the combined result has an error of less than 1%, which is less than one-third of the systematic error.

[0045] Figure 6 An electrode film material 600 and a non-staggered array of electromagnetic coil pairs 602 arranged in parallel rows and columns are shown. Figure 6 Only the top coil 604 of each of these pairs is shown. The bottom coils of these pairs are located below the electrode film material 600 and are horizontally aligned with the corresponding top coils. The effective pitch (or the closest distance between the centers of the coils in the lateral direction) is designated as 606. The movement of the electrode film material 600 is represented by arrow 608.

[0046] Figure 7 An electrode film material 700 is shown, along with a staggered array of electromagnetic coil pairs 702 arranged in parallel rows and offset columns. Figure 7 Only the top coil 704 of each of these pairs is shown. The bottom coils of these pairs are located below the electrode film material 700 and are horizontally aligned with the corresponding top coils. The effective pitch (or the closest distance between the centers of the coils in the lateral direction) is designated as 706. By offsetting the coils, the effective pitch is reduced. Figure 7 The arrangement provides an effective pitch smaller than that provided by Figure 6 The arrangement of provides an effective pitch. The staggered array of coils improves lateral resolution. The movement of the electrode film material 700 is represented by arrow 708.

[0047] Figures 6 to 7 The coil array may be arranged separately from the roller, or may be incorporated into the roller. For example, the array may be incorporated into a calender roller and / or other rollers (such as the and / or Figures 1 to 2 This may be done to minimize peeling variations.

[0048] The coil pairs may be triggered periodically and / or in a predetermined pattern. In an embodiment, each of the coil pairs is triggered periodically to track thickness variations along a longitudinal line extending in the direction of motion of the corresponding electrode film material being evaluated.

[0049] In another embodiment, one or more coil pairs are mounted on a C-arm with an upper coil on one end of the C-arm and a lower coil mounted on a second end of the C-arm.The C-arm moves laterally to scan thickness variations laterally across the electrode film material.

[0050] The coil pairs can be arranged in various patterns relative to the electrode film material. For example, the coil pairs can be arranged in a staggered pattern, a diagonal pattern, a triangular pattern, etc. The timing of the coil pairs can be staggered to capture thickness changes along a single line that extends across the corresponding electrode film material being evaluated. The line can extend laterally across the electrode film material in a direction perpendicular to the direction of material movement, and / or extend diagonally across the electrode film material.

[0051] The drive signal provided to the transmit coil in the coil pair and / or a reference signal proportional to the drive signal can be monitored and multiplexed. Furthermore, the signal generated by the receive coil in the coil pair can also be multiplexed. This is done to minimize the number of data channels used to drive the transmit coil and the number of channels used to receive the signal generated at the receive coil. Fig. 9 An example multiplexer is shown in .

[0052] Figure 8 A dual-stage eddy current NDE circuit 800 configured for a coil pair, such as any coil pair mentioned herein, is shown. The dual-stage eddy current NDE circuit 800 includes a control module 802, a field programmable gate array (FPGA) 804, a digital-to-analog converter (DAC) 806, a low pass filter (LPF) 808, a switching circuit 809, a first amplifier 810, a first coil 812, a second coil 814, and a second amplifier 816. In one embodiment, the FPGA 804 and the control module 802 are implemented as a single control module. In another embodiment, the FPGA 804 and the control module 802 are implemented as separate control modules. An oscillator 818 generates an oscillation signal, which is provided to a clock generator 820. The clock generator 820 generates one or more clock signals based on the oscillation signal, which can be provided to the FPGA 804. The FPGA 804 concurrently outputs one or more signals having corresponding frequencies to the DAC 806 based on the one or more clock signals. For example, the frequency can be between 5 MHz and 40 MHz. FPGA 804 is configured to selectively adjust multiple signals output concurrently, the frequency of the signals, and the timing of the signals. FPGA 904 can implement the superposition of tone bursts of multiple frequencies into one signal. In another embodiment, FPGA 804 implements chirping for time-invariant cycle time reduction (e.g., 200 μs for a 100 m / min roll speed). Chirping includes pulse signaling with a changing frequency.

[0053] The FPGA 804 or control module 802 shown may control the switching performed by the switching circuit 809. The switching includes switching between phase 1 and phase 2. The FPGA 804 may, for example, generate an image signal having a frequency centered around 200 MHz. The LPF 808 suppresses high order frequencies to eliminate aliasing effects of the drive signal.

[0054] DAC 806 is a 2-channel DAC, including a first channel for transmission and a second channel for internal data processing and down conversion to provide a local oscillator signal. The output of the first channel (or transmission channel) is a transmission signal provided to LPF 808. LPF filters the transmission signal and outputs the filtered signal to the first amplifier 810 (referred to as a driver). As an example, the filtered transmission signal can be a 20MHz signal or a signal with multiple frequencies between 5MHz and 40MHz. The corresponding amplifiers in amplifiers 810 and 816 amplify the filtered signal, which is then transmitted as a drive signal via one of coils 812 and 814 (referred to as the transmission coil for the current stage). An electromagnetic field is generated by the electrode film material 821, and an EMF voltage (received signal) is generated at the second coil (referred to as the receiving coil) in coils 812 and 814. The EMF voltage is amplified by the second corresponding amplifier in amplifiers 810 and 816.

[0055] The local oscillator (LO) signal generated by the DAC 806 via the second channel of the DAC 806 is provided to the multipliers 822, 824. The multiplier 822 multiplies the LO signal (e.g., a 15 megahertz (MHz) sine wave) by the reference signal from the corresponding amplifier in the amplifiers 810, 816 to provide a down-conversion reference signal. The reference signal is proportional to the drive signal. The multiplier 824 multiplies the LO signal by the output of the second amplifier in the amplifiers 810, 816, which is a received signal that has been amplified and is at the same frequency as the drive signal. The received signal is proportional to the AC attenuation magnetic field generated by the transmission of the drive signal. The output of the multiplier 824 is referred to as the down-conversion EMF (or reception) signal. As an example, the down-conversion reference signal and the down-conversion received signal can be signals of 1MHz to 5MHz. The output of the multipliers 822, 824 is provided to the analog-to-digital converter (ADC) 826. ADC 826 is a dual channel ADC that outputs analog signals representing the outputs of multipliers 822 , 824 to FPGA 804 .

[0056] The above operation is repeated after switching to the second stage, so that the second coil of coils 812, 814 is a transmitting coil and the first coil of coils 812, 814 is a receiving coil. FPGA 804 and / or control module 802 can then combine and / or average the down-converted EMF signals from stage 1 and stage 2. FPGA 804 and / or control module 802 can convert the down-converted EMF signal into a complex transmission coefficient, which can then be averaged. The complex transmission coefficient is proportional to the ratio between the EMF voltage and the reference signal. The average value can then be converted into the thickness of the electrode film material. The stated conversion can be implemented by software executed by FPGA 804 and / or control module 802. The conversion can be performed using equations, relationships, plots, tables, etc. In one embodiment, a table is used to convert the average complex transmission coefficient into thickness. The thickness can be determined based on the average value of the amplitude of the complex transmission coefficient and / or the average value of the phase. The determined average value and / or thickness can also be used to detect the defects mentioned above.

[0057] By monitoring the drive signal and the received signal, and by normalizing the EMF voltage of the received signal with respect to the drive signal, changes due to thermal drift can be detected and accounted for to improve the accuracy of the resulting thickness.

[0058] A wireless module 830 may be included and connected to the control module 802. The wireless module 830 may communicate the results from the circuit 800 to a device located remotely from the circuit 800.

[0059] Circuit 800 can operate in a single-sided (single-phase) mode or a double-sided (dual-phase) mode. Single-phase mode refers to operating one coil as a transmit coil and the other coil as a receive coil. As described above, dual-phase mode refers to operating each of the coils as a transmit coil and a receive coil in an alternating manner.

[0060] Fig. 9 Shows something like Figure 8 The eddy current NDE circuit 900 of the eddy current NDE circuit can be operated in a single phase or a dual phase mode. In addition, the circuit 900 is configured for an array of coil pairs. Fig. 9 is also shown for phase 1, but is similarly connected for phase 2, except that the transmit coil operates as a receive coil and the receive coil operates as a transmit coil. The switching circuitry for switching between phase 1 and phase 2 is also not shown in FIG. Fig. 9 , but similar to Figure 8900. The eddy current NDE circuit 900 includes a control module 902, an FPGA 904, a DAC 906, an LPF 908, a first amplifier 910, a first (or transmitting) coil 912, a second (or receiving) coil 914, a second amplifier 916, multiplexers 918, 919, and multipliers 920, 922. In one embodiment, the FPGA 904 and the control module 902 are implemented as a single control module. In another embodiment, the FPGA 904 and the control module 902 are implemented as separate control modules.

[0061] The circuit 900 further includes an oscillator 924 that generates an oscillation signal that is provided to a clock generator 926. The clock generator 926 generates one or more clock signals based on the oscillation signal that can be provided to the FPGA 904. The FPGA 904 concurrently outputs one or more signals having corresponding frequencies to the DAC 906 based on the one or more clock signals. The FPGA 804 is configured to selectively adjust the number of concurrently outputted signals, the frequency of the signals, and the timing of the signals. The FPGA 904 or the control module 902 shown can control the switching performed between phase 1 and phase 2. The LPF 908 suppresses high-order frequencies to monitor the drive signal generated by the amplifier 910.

[0062] LPF 908 filters the received signal and outputs the filtered signal to first amplifier 910 (referred to as driver). Amplifier 910 amplifies the filtered signal. The amplified signal is transmitted as a drive signal via one of coils 912 (referred to as a transmission coil for the current stage). An electromagnetic field is generated by electrode film material 921, and an EMF voltage (received signal) is generated at coil 914 (referred to as a receiving coil). The EMF voltage is amplified by amplifier 916.

[0063] The reference signal output by amplifier 910 is provided to first multiplexer 918. First multiplexer 918 selects one of the received signals to provide to multiplier 920. The local oscillator signal generated by DAC 906 is provided to multipliers 920, 922. Multiplier 920 multiplies the local oscillator signal (e.g., 5 to 15 MHz signal) by the selected reference signal to provide the resulting reference signal. Multiplexer 919 selects one of the EMF signals output by amplifier 916. Multiplier 922 multiplies the local oscillator signal by the selected one of the EMF signals. The output of multiplier 922 is referred to as the down-converted EMF signal. The output of multipliers 920, 922 is provided to analog-to-digital converter (ADC) 927. ADC 927 is a dual-channel ADC, which outputs analog signals representing the outputs of multipliers 918, 919 to FPGA 904. The selection performed by multiplexers 918 , 919 may be made by FPGA 904 and / or control module 902 .

[0064] Coils 912, 914 may be similar to Figures 6 to 7 The on and off timing, phase, duty cycle, frequency, etc. of the signals transmitted by coils 912, 914 can be adjusted and set. The timing can be controlled for concurrent and / or sequential selection of coil pairs.

[0065] A wireless module 930 may be included and connected to the control module 902. The wireless module 930 may communicate the results from the circuit 900 to a device located remotely from the circuit 800.

[0066] Stripping compensation from Figure 4 As can be seen from the plots, if the actual peel is unknown, then there is a random error component. For example, a vertical shift of +100 μm introduces a 2% error. A vertical shift of -100 μm provides a 3% error. If the peel distance variation is unknown, then the error cannot be corrected. However, if the peel distance variation can be determined, then it can be determined by looking at Figure 4 The errors are minimized and / or eliminated by plotting the sample and compensating for the corresponding errors. After correcting for errors that may be introduced due to vibrations of the electrode film material, the "vibration-free" complex transmission coefficient is determined as if the sample were kept in the center (symmetry plane) position between the coils. The thickness of the sample can be determined based on the "vibration-free" complex transmission coefficient by calibration using known samples or finite element model simulations or other numerical methods.

[0067] Fig.10 A coil pair 1000, 1002 for eddy current NDE of electrode film material 1004 and a capacitive sensor 1006 for accounting for high lift-off are shown. Fig.11Coil pairs 1000, 1002 and electrode film material 1004 are shown. Fig.12 Capacitive sensor 1006 is shown. Coils 1000, 1002 can be operated as described above to determine the thickness of electrode film material 1004. Capacitive sensor 1006 can extend through the middle of coil 1000 and have a bottom surface vertically aligned with the bottom surface of coil 1000, so that capacitive sensor 1006 and coil 1000 are at the same distance from electrode film material 1004. Capacitive sensor 1006 is used to characterize the nonlinear response in the coil measurement for correction. This is done using high precision peeling measurement via capacitive sensor 1006.

[0068] Capacitive sensor 1006 includes measurement electrode 1010, guard ring electrode 1012, outer ground shell 1014 and signal line 1016. Capacitive sensor 1006 measures the capacitance between the capacitive sensor head (i.e., measurement electrode 1010) and the electrode film material 1004. A guard field 1016 generated by guard ring electrode 1012 is shown. Capacitive sensor 1006 operates independently of eddy current coils 1000, 1002. In one embodiment, capacitive sensor 1006 is included to obtain accurate measurement of peeling distance for compensation in post-processing of signals obtained for thickness measurement using eddy current coils 1000, 1002. When there is a large amount of peeling variation (non-uniform magnetic field), such as, for example, more than 1 / 3 peeling (or more than 1 / 3 distance change between coil and electrode film material), the peeling distance measured by capacitive sensor 1006 can be used. Capacitive sensor 1006 and the like can be used in combination with any embodiment disclosed herein. The data output by capacitive sensor 1006 can be received by one of the control modules disclosed herein.

[0069] Fig.13 A pair of coils 1300, 1302 for eddy current NDE of electrode film material 1304 and a laser vibrometer 1306 for accounting for high delamination are shown. Coils 1300, 1301 can be operated as described above to determine the thickness of electrode film material 1304. Laser vibrometer 1306 operates independently of eddy current coils 1300, 1302. Laser vibrometer 1306 and the like can be used in conjunction with any of the embodiments disclosed herein. Data collected by the laser vibrometer can be stored in memory 1308, which can be shared with one of the control modules mentioned herein. In one embodiment, laser vibrometer 1306 is included to obtain an accurate measurement of delamination distance for compensation in post-processing of signals obtained for thickness measurement using eddy current coils 1300, 1302. When there is a large amount of delamination variation (non-uniform magnetic field), such as, for example, delamination of more than 1 / 3, the delamination distance measured by laser vibrometer 1306 can be used.

[0070] Another technique that can be used to measure high peeling includes using one or more eddy current coils (e.g. one of the eddy current coils used for thickness determination). The operating frequency of the one or more eddy current coils is higher for peeling determination than for thickness determination (or two-stage transmission mode measurement). The electromagnetic field generated at the frequency used for thickness determination passes through the electrode film material. This is different from the electromagnetic field generated at the frequency used for peeling determination.

[0071] As an example, the coil disposed above the sample (or electrode film material) and the coil disposed below the sample work independently. high (e.g. 100MHz) to drive the coil above the sample. high For skin depths of a few microns, the sample (electrode membrane material) cannot be penetrated. high The penetration depth of the eddy currents is much less than the thickness of the thin sample being measured, and therefore from the perspective of the coil above the sample, the thin sample appears as an infinitely thick material. For example, if we choose 500MHz as f high , then the penetration depth for lithium is 6.78μm. If the thickness of the thin lithium sample is more than 3 times this value, for example 20μm, then from the perspective of the coil above the sample, it makes no difference whether the sample is 20μm or 20 meters thick, because not much AC magnetic field can penetrate the sample. At this stage, the impedance of the coil above the sample depends only on the peeling distance of the coil. By comparing the impedance of the coil above the sample in this mode with the impedance of the coil in air (away from any metal), a comparison value is generated. The comparison value is stored as part of the calibration data set, and the peeling distance is then determined based on the comparison value.

[0072] Since the distance between the two coils is known, the process is not repeated for the coil under the sample. The lift-off of the coil under the sample is equal to the gap between the two coils minus the lift-off distance of the coil above the sample. This process is separate from the actual thickness measurement, and since the operating frequency is very high, the amount of additional time to determine the lift-off is minimal (e.g., 5 μs additional time per point).

[0073] When high peeling is present, it can be based on and / or using Figures 10 to 12 The above-mentioned capacitive sensor 1006, the above-mentioned Fig.13 The thickness determination may be adjusted using peel measurements provided by a laser vibrometer 1306 and / or eddy current coils as described above operating at a high frequency (e.g., 100 MHz).

[0074] Regardless of how the peel distance is acquired (capacitive sensor, laser vibrometer, or high frequency single coil mode), a correction to the raw complex transmission coefficient can be made based on the peel distance. The raw complex transmission coefficient refers to the data acquired directly from the measurement hardware without post-processing or calibration. In one embodiment, a lookup table is used to determine the pre-calculated correction factor based on the peel distance. The lookup table can be obtained by combining finite element simulation results and actual measurement results from a sample with a known thickness.

[0075] Fig.14 A plot of the phase of impedance versus frequency is shown. As the frequency of the signal supplied to the coil increases, the phase of the impedance of the coil generally increases for a particular usable operating frequency range. Within this range, the coil operates as an inductor (i.e., has an inductance). If the frequency exceeds a predetermined frequency, the coil no longer operates as an inductor and has a capacitance. For the purposes of the disclosed examples, the eddy current coils referred to herein operate within a frequency range such that the coil has an inductance and operates as an inductor.

[0076] Fig.15 Polar plots of attenuation versus signal frequency change for two different electrode film material thicknesses are shown. The first material thickness is greater than the second material thickness. The first attenuation curve 1500 corresponds to the first thickness and is associated with a frequency change from, for example, 8 MHz to 21 MHz. The second attenuation curve 1502 corresponds to the second thickness and is associated with a frequency change from, for example, 8 MHz to 21 MHz. The values ​​of the attenuation curves 1500, 1502 are negatively correlated with the corresponding complex transmission coefficients determined using the above method for determining thickness.

[0077] Figure 16 illustrates the eddy current NDE method. The method can be performed iteratively. Figures 1 to 2 and Figures 6 to 13 The method can be performed for each pair of eddy current coils. Figure 2 and 8 The following operations are described, but may be implemented with respect to other embodiments of the present disclosure.

[0078] At 1600, one or more clock signals are generated via clock generator 820. At 1602, FPGA 804 generates a digital transmission signal including one or more signals having corresponding one or more frequencies on a single channel.

[0079] At 1604, the DAC 806 converts the digital transmission signal to an analog signal. At 1606, the LPF 808 filters the analog signal to remove higher order frequencies.

[0080] At 1607, the switching circuit is set for the current phase. This includes setting the connections so that the first one or more coils will operate in a transmission mode and the second one or more coils will operate in a reception mode.

[0081] At 1608, one of the amplifiers 810, 816 amplifies the filtered signal to provide a drive signal. If more than one transmit coil is driven, more than one amplifier may amplify the drive signal in parallel.

[0082] At 1610, one of the coils 812, 814 operating in the transmission mode receives the drive signal and generates an electromagnetic field. If more than one coil is operating in the transmission mode, the more than one coil receives a corresponding drive signal and generates a corresponding electromagnetic field.

[0083] At 1612, the other coil of the coils 812, 814 operating in the receiving mode generates an EMF voltage based on the electromagnetic field. If more than one coil operates in the receiving mode, the more than one coil generates corresponding EMF voltages.

[0084] At 1614, another of the amplifiers 810, 816 amplifies the output of the coil operating in the receive mode. If more than one coil is operating in the receive mode, the more than one amplifier amplifies the respective outputs of the coils operating in the receive mode.

[0085] At 1616 , the multiplier and / or other multipliers down-convert the amplified received signal provided at 1614 into a down-converted received signal. Operation 1621 may be performed after operation 1616 .

[0086] The following operations 1618 and 1620 may be performed in parallel with operations 1610, 1612, 1614, and 1616. At 1618, one or more amplifiers that amplify the filtered signal generate a reference signal, as described above. At 1620, the multiplier and / or other multipliers down-convert the reference signal to provide a down-converted reference signal. Operation 1621 may be performed after operation 1620.

[0087] At 1621, ADC 826 converts the down-converted received signal and the down-converted reference signal into a digital signal, which is provided to FPGA 804. At 1622, FPGA 804 and / or control module 802 determines whether to perform another stage. If so, operation 1624 is performed, otherwise operation 1626 is performed.

[0088] At 1624, the switching circuit 809 is set for the next stage. This can be performed via the FPGA 804 and / or the control module 802. This includes switching the first one or more coils operating in the transmission mode to operate in the reception mode, and switching the second one or more coils operating in the reception mode to operate in the transmission mode. This can also include stopping the generation of the reference signal at the first amplifier (multiple) and initiating the generation of the reference signal at the second amplifier (multiple). Operation 1600 can be performed after operation 1624.

[0089] At 1626, the FPGA 804 and / or the control module 1602 determine one or more thicknesses of the sample (or electrode film material) between each pair of coils involved, as described above. At 1628, the peel distance may be determined using any of the above methods. At 1630, the thickness is adjusted based on the peel distance, as described above. In one embodiment, operation 1630 is performed when the peel distance is greater than a predetermined amount (e.g., more than 1 / 3 of the distance between i) the center position between the coil pair and ii) one of the coils in the coil pair).

[0090] At 1632, the FPGA 804 and / or control module 802 performs feedback and / or feedforward control of the actuators and motors 231, 233, as described above. At 1634, the FPGA 804 and / or control module 802 determines whether to perform another iteration of the method. If so, operation 1600 is performed, otherwise the method ends.

[0091] The above examples include a through-transmission eddy current method for accurately assessing the thickness of electrodes including lithium metal anodes during roll-to-roll manufacturing (battery manufacturing process). The disclosed hardware implements a two-stage measurement routine that significantly reduces measurement errors due to sample vibration. The described method accounts for and / or is insensitive to vibration and vertical peeling, and therefore provides accurate thickness measurements when the sample being evaluated is vibrating and / or moving vertically. This allows accurate feedback and feed-forward control of thickness to improve thickness uniformity for producing cathodes that meet capacity requirements.

[0092] The foregoing description is merely illustrative in nature and is by no means intended to limit the present disclosure, its application or use. The broad teachings of the present disclosure can be implemented in a variety of forms. Therefore, although the present disclosure includes specific examples, the true scope of the present disclosure should not be so limited, because other modifications will become apparent when studying the drawings, the specification and the following claims. It should be understood that, without changing the principles of the present disclosure, one or more steps in the method can be performed in different orders (or simultaneously). In addition, although each embodiment is described above as having certain features, any one or more of those features described with respect to any embodiment of the present disclosure can be implemented in the features of any other embodiment and / or combined with the features of any other embodiment, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and one or more embodiments and each other's permutation (permutation) are still within the scope of the present disclosure.

[0093] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including "connected," "engaged," "coupled," "adjacent," "immediately adjacent," "on," "above," "below," and "disposed." Unless explicitly described as "direct," when describing a relationship between a first and a second element in the above disclosure, the relationship may be a direct relationship in which no other intervening elements exist between the first and second elements, but may also be an indirect relationship in which one or more intervening elements (either spatially or functionally) exist between the first and second elements. As used herein, the phrase "at least one of A, B, and C" should be interpreted to mean a logical (A or B or C) using a non-exclusive logical "or," and should not be interpreted to mean "at least one of A, at least one of B, and at least one of C."

[0094] In the various figures, the direction of the arrow, as indicated by the arrow head, generally indicates the flow of information (such as data or instructions) of interest to the illustration. For example, when element A and element B exchange various information, but the information transmitted from element A to element B is relevant to the illustration, the arrow may point from element A to element B. The unidirectional arrow does not imply that no other information is transmitted from element B to element A. In addition, for information sent from element A to element B, element B may send a request or a receipt confirmation of the information to element A.

[0095] In this application, including the definitions below, the term "module" or the term "controller" may be replaced with the term "circuit". The term "module" may refer to, be part of, or include: an application specific integrated circuit (ASIC); a digital, analog, or mixed analog / digital discrete circuit; a digital, analog, or mixed analog / digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or grouped) that executes code; a memory circuit (shared, dedicated, or grouped) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system on a chip.

[0096] The module may include one or more interface circuits. In some examples, the interface circuit may include a wired or wireless interface connected to a local area network (LAN), the Internet, a wide area network (WAN), or a combination thereof. The functions of any given module of the present disclosure may be distributed among multiple modules connected via the interface circuit. For example, multiple modules may allow load balancing. In a further example, a server (also referred to as a remote or cloud) module may implement some functions on behalf of a client module.

[0097] The term "code" as used above may include software, firmware, and / or microcode, and may refer to a program, a routine, a function, a class, a data structure, and / or an object. The term "shared processor circuit" covers a single processor circuit that executes some or all code from multiple modules. The term "group processor circuit" covers a processor circuit that executes some or all code from one or more modules in conjunction with an additional processor circuit. References to multiple processor circuits cover multiple processor circuits on discrete dies, multiple processor circuits on a single die, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or a combination of the above. The term "shared memory circuit" covers a single memory circuit that stores some or all code from multiple modules. The term "group memory circuit" includes a memory circuit that stores some or all code from one or more modules in conjunction with additional memory.

[0098] The term "memory circuit" is a subset of the term "computer-readable medium". The term "computer-readable medium" as used herein does not encompass non-transitory electrical or electromagnetic signals propagated through a medium (such as on a carrier wave); therefore, the term "computer-readable medium" may be considered to be tangible and non-transitory. Non-limiting examples of non-transitory tangible computer-readable media are non-volatile memory circuits (such as flash memory circuits, erasable programmable read-only memory circuits, or mask read-only memory circuits), volatile memory circuits (such as static random access memory circuits or dynamic random access memory circuits), magnetic storage media (such as analog or digital magnetic tape or hard disk drives), and optical storage media (such as CDs, DVDs, or Blu-ray discs).

[0099] The apparatus and method described in the present application can be implemented in part or in whole by a special-purpose computer, which is created by configuring a general-purpose computer to perform one or more specific functions embodied in a computer program. The functional blocks, flow chart components and other elements described above act as software specifications, which can be translated into computer programs by the routine work of skilled technicians or programmers.

[0100] The computer program includes processor executable instructions stored on at least one non-transitory tangible computer readable medium. The computer program may also include or rely on stored data. The computer program may include a basic input / output system (BIOS) that interacts with the hardware of the special-purpose computer, device drivers that interact with specific devices of the special-purpose computer, one or more operating systems, user applications, background services, background applications, etc.

[0101] A computer program may include: (i) descriptive text to be parsed, such as HTML (Hypertext Markup Language), XML (Extensible Markup Language), or JSON (JavaScript Object Notation), (ii) assembly code, (iii) object code generated by a compiler from source code, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. By way of example only, source code may be written using syntax from languages ​​including: C, C++, C#, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Fortran, Perl, Pascal, Curl, OCaml, HTML5 (Hypertext Markup Language Version 5), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Visual Lua, MATLAB, SIMULINK, and

Claims

1. An eddy current non-destructive evaluation system for electrode film materials, the system comprising: at least one control module configured to generate a transmission signal; as well as The first coil pair comprises a first coil disposed adjacent to the electrode film material and configured to operate in a transmission mode and generate an electromagnetic field through the electrode film material based on the transmission signal, and a second coil disposed adjacent to the electrode film material and disposed on a side of the electrode film material opposite to the first coil and configured to operate in a receiving mode, wherein the second coil is configured to generate a first electromagnetic field voltage based on the electromagnetic field, and The at least one control module is configured to perform at least one of the following operations based on the first electromagnetic field voltage: determine a first thickness of the electrode film material, and detect defects of the electrode film material.

2. The system of claim 1, wherein the at least one control module is configured to: operate the first coil in a receiving mode and operate the second coil in a transmitting mode so that the first coil generates a second electromagnetic field voltage, and determine the first thickness based on the second electromagnetic field voltage.

3. The system of claim 2, wherein the at least one control module is configured to: i) determine a first complex transmission coefficient based on a first electromagnetic field voltage, ii) determine a second complex transmission coefficient based on a second electromagnetic field voltage, iii) average the first complex transmission coefficient and the second complex transmission coefficient, and iv) determine the first thickness based on the average.

4. The system of claim 1 , further comprising a switching circuit connected between i) the at least one control module and ii) the first coil and the second coil, wherein the at least one control module is configured to control the switching circuit to transition operation of the first coil and the second coil between operating in the transmission mode and the reception mode.

5. The system of claim 1 , further comprising an amplifier configured to generate a drive signal based on the transmission signal to drive the first coil, and to generate a reference signal proportional to the drive signal, Wherein the at least one control module is configured to determine a first thickness based on the reference signal.

6. The system according to claim 5, further comprising: a first multiplier configured to down-convert the reference signal into a down-converted reference signal; as well as a second multiplier configured to down-convert the received signal into a down-converted received signal, in The second coil generates the receiving signal including the first electromagnetic field voltage, The at least one control module is configured to determine a first thickness based on the down-converted reference signal and the down-converted received signal.

7. The system of claim 1, wherein the transmission signal comprises a plurality of frequencies.

8. The system of claim 1, further comprising: The second coil pair comprises a third coil disposed adjacent to the electrode film material and configured to operate in a transmission mode and generate an electromagnetic field through the electrode film material based on the transmission signal, and a fourth coil disposed adjacent to the electrode film material and disposed on a side of the electrode film material opposite the third coil and configured to operate in a receive mode, wherein the fourth coil is configured to generate a second electromagnetic field voltage based on the electromagnetic field generated by the third coil; as well as a first multiplexer configured to select between the second coil and the fourth coil, Wherein the at least one control module is configured to control a state of the first multiplexer and determine the second thickness based on the second electromagnetic field voltage.

9. The system of claim 1 , further comprising at least one of a capacitive sensor and a laser vibrometer configured to determine a peeling distance between the electrode film material and one of the first coil and the second coil, Wherein the at least one control module is configured to adjust the first thickness based on the peel distance.

10. The system of claim 1, wherein the at least one control module is configured to operate the first coil to determine a peel distance between the electrode film material and one of the first coil and the second coil, and adjust the first thickness based on the peel distance.

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