Method and apparatus for imaging electrochemical cell electrodes

Abstract

An electrochemical cell (300) is provided, comprising a working electrode (306), a transparent window (320) configured to allow light to reach the working electrode (306), and a partially reflective layer (304) including one or more regions configured to reflect electromagnetic radiation and one or more regions (322) configured to transmit electromagnetic radiation, wherein the partially reflective layer (304) is in mechanical communication with the working electrode (306) and is configured such that changes therein indicate corresponding changes in the working electrode (306), and the working electrode (306) is in substantially continuous contact with the transparent window (320) or the partially reflective layer (304).

Description

【Technical Field】 【0001】 The present invention relates to a method and an apparatus for imaging an electrode. Specifically, the present invention relates to imaging an electrochemical cell electrode in an optically accessible electrochemical cell using an optical microscope during an electrochemical process, but is not limited thereto. Prior art 【0002】 In order to advance battery technologies such as those based on lithium-ion battery technology, it is useful to understand how battery materials function at the nano- to mesoscale during real-time operation. For example, it has been demonstrated that optical measurements of electrochemical cell electrodes during an electrochemical process (such as charging and discharging) can provide useful mechanistic information (Merryweather et al., Nature, Vol. 594, 2021, pages 522-528). In contrast to conventional methods of performing operando imaging of lithium-ion dynamics based on sophisticated cyclotron X-ray or electron microscopy techniques, the use of optical scattering microscopy has been shown to elucidate lithium-ion dynamics in battery materials at the nanoscale in a simple manner suitable for high-throughput analysis. 【0003】 However, although the charging, discharging, and degradation mechanisms of individual particles (e.g., LixCoO2 particles) within the electrode matrix have been investigated in such experiments, previous studies of such electrochemical processes have been limited to dilute electrodes. In this context, the term “dilute” shall be used as a broad term encompassing porous, self-supporting electrodes containing active material particles, such as LixCoO2, with a relatively low density compared to conventional electrodes with a relatively high density of active material particles. The relatively sparse distribution of active material particles within the inert matrix means that changes to the active material particles in electrochemical processes such as charging and discharging can be monitored by reference to the inert matrix. For example, a reference laser beam with a spot size that can penetrate between the active material particles, emitted toward the inert matrix, can be used as a reference point for adjusting the imaging focus of an imaging device to elucidate any positional changes on the electrode surface during the electrochemical process. For example, using a reference laser beam with a spot size of 8 to 15 microns at half maximum width means that the spot is far larger than the roughness of the inert matrix in the regions between the active material particles, which means that sharp reflections will occur. In contrast, if the active material particles are packed at high density, as in conventional electrodes, the electrode surface is too rough to apply this technique. This is because the spacing between the active material particles is smaller than the spot size of such a laser beam. Furthermore, the change in active particles during the electrochemical process means that the surface of such a densely packed conventional electrode does not produce consistent reflections that can be used to assist in adjusting the imaging focus during the electrochemical process. 【0004】 To perform optical measurements while a dilution electrode is in operation, a relatively complex operando cell apparatus can be used. Figure 1A shows an exploded view of a prior art system example 100 for analyzing the electrochemical properties of a dilution electrochemical cell electrode 104 by scattering microscopy. System 100 comprises an optical device 120 used to examine the dilution electrochemical cell electrode 104 in the operando cell apparatus. The operando cell apparatus includes a light window 102 within a lower housing 101, which allows light to reach the dilution electrode 104. The dilution electrode 104 is a freestanding electrode of powdered lithium cobalt oxide dispersed in a polymer matrix. The freestanding dilution electrode 104 is in electrical contact with an aluminum mesh 106, while the aluminum mesh 106 is in electrical contact with a probe 108 to form a working electrode. The aluminum mesh 106 is separated from a lithium metal material 111 and another probe 112 by a separator 110. The lithium metal material 111 and the probe 112 together form a counter electrode. The upper housing 103 works in conjunction with the lower housing 101 to seal half of the cell stack. Half of the cell stack is moistened with standard lithium hexafluoride phosphate (LiPF6) and carbonate liquid electrolyte (LP30). 【0005】 The optical device 120 includes a laser diode as a light source 122, which is guided and passes through the light window 102 of the operand cell device, as indicated by the arrow 114. Before passing through the light window 102, the light passes through a series of optical components, including a lens 124, a polarizing beam splitter 126, a quarter-wave plate 128, and an objective lens 130. The light source 122 is used to illuminate the dilution electrode 104, and the optical components are arranged so that the incident light focuses on the active particles in the dilution electrode 104, and the light scattered by the active particles is then focused by another lens 132, and the focused light is imaged by a complementary metal-oxide-semiconductor (CMOS) camera 134. Such a system makes it possible to image the dilution electrochemical cell electrode while supplying a desired current-voltage state to the operand cell device. 【0006】 The operando cell devices described above are modular and reusable, but they are not suitable for routine battery testing because they are relatively expensive, difficult to assemble, and their cyclical behavior is considered unreliable. 【0007】 To gain a deeper understanding of processes during the real-time operation of conventional electrochemical cells, such as coin-type cells, it would be useful to investigate conventional electrochemical cells from an optical perspective during electrochemical processes. Specifically, it would be useful to investigate high-density conventional electrochemical cell electrodes from an optical perspective during electrochemical processes. 【0008】 Figure 1B shows a cross-sectional view of a prior art conventional electrochemical coin cell 200. Inside the coin cell 200, a stack of layers including a foil layer 204 is shown, with a working electrode layer 206 located on top of it. The foil layer 204 is in electrical contact with the first component of the housing 202 of the coin cell 200. 【0009】 The working electrode layer 206 is separated from the counter electrode 210 by a separator 208. Between the counter electrode 210 and the second component of the cell housing 216 are a spacer layer 212 and a spring 214. Conventional electrochemical coin cells do not transmit any light. This is because the first component of the housing 202 and the foil layer 204 are optically opaque, thus preventing light from reaching one plane of the working electrode layer 206. In addition, the separator 208, the counter electrode 210, the spacer layer 212, and the second component of the housing 216 also prevent light from reaching the other plane of the working electrode layer 206 that is opposite to the plane adjacent to the foil layer 204. 【0010】 As explained earlier, such conventional electrochemical cells not only fail to allow light to reach the active material, but even if they do, the rough surface of the high-density electrochemical cell electrode makes real-time imaging difficult due to the high density of the active material particles compared to the relatively low-density active material particles in the dilution electrode. This is because changes in the high-density active material particles during operation cannot be tracked by referring to the inert matrix, as is possible with the dilution electrochemical cell electrode. 【0011】 Furthermore, if the configuration of the mesh layer 106 and the dilution electrochemical electrode 104, as described with reference to Figure 1A, is replaced with a conventional high-density packed electrochemical cell electrode molded on a foil layer, the electrolyte inside such an operand cell cannot penetrate the conventional foil layer and reach the active material of the electrochemical cell electrode. This is in contrast to the prior art self-supporting dilution electrochemical cell electrode, which, being porous (and without a foil layer), allows the electrolyte to reach sparsely distributed active material particles through a self-supporting matrix. 【0012】 In addition, the art is known to provide electrochemical cells through which electrodes can be reached via gaps or holes in the current collector. In this configuration, the working electrode is not in continuous contact with either a transparent window or a partially reflective layer. Typically, the current collector foils used can have thicknesses greater than 15 μm, but they also have high surface roughness of 500 nm between peaks, resulting in considerable variability. High surface roughness of the working electrode can make it difficult to reliably find the planar region that the autofocus beam reflects. If the surface is not flat, the spot imaged for focusing becomes structured. This means that even small changes in the horizontal and / or vertical (X,Y) directions of the microscope can be interpreted as false focus shifts. [Overview of the Initiative] [Problems that the invention aims to solve] 【0013】 Therefore, in order to improve the imaging quality of the working electrode, the electrochemical process is designed to increase reliability, consistency, and reflect the autofocus beam more efficiently. There is a need to provide an electrochemical cell having a working electrode with low surface roughness. 【0014】 This invention was made against this background. [Means for solving the problem] 【0015】 To mitigate at least some of the problems described above, an electrochemical cell is provided. This electrochemical cell comprises a working electrode, a transparent window configured to allow light to reach the working electrode, and a partial reflective layer including one or more regions configured to reflect electromagnetic radiation and one or more regions configured to transmit electromagnetic radiation, wherein the partial reflective layer is in mechanical communication with the working electrode and is configured such that changes therein indicate corresponding changes in the working electrode, and the working electrode is in substantially continuous contact with either the transparent window or the partial reflective layer. 【0016】 Within the context of the present invention, and unless otherwise specified, “working electrode” comprises a layer or particles of active material for initiating an electrochemical process or reaction. This working electrode does not include a current collector, which may be made of mesh or foil. 【0017】 Within the context of the present invention, the term "continuous contact" should be understood to mean that the working electrode is in contact at all points along its underside. In other words, the contact between the working electrode and the transparent window or partial reflective layer is non-discontinuous, and the underside of the working electrode is always in continuous contact with one of the surfaces of the transparent window or reflective layer. 【0018】 Where disclosed herein, and unless otherwise specified, continuous contact between the working electrode and the transparent window or reflective layer means that, at a macroscopic level, there is no interruption in the contact, for example, there are no intervals, gaps, spaces, ports, or holes between these layers that interrupt the contact between the transparent window or reflective layer and the working electrode. 【0019】 Contact exists between the portion with the transparent window and the other portions of the reflective layer across the entire range of the working electrode. There are no gaps in contact with the working electrode. There are no portions of the working electrode that are in contact with both the transparent window and the reflective layer simultaneously. The working electrode may have any structural form or pattern known to those skilled in the art. For example, the working electrode may have one or more trenches or wells within its structure. 【0020】 In some embodiments, the working electrode may be in substantially solid continuous contact with either a transparent window or a reflective layer over its entire length. In contrast, an electrochemical cell configuration is also known in which light reaches the working electrode through a hole in the current collector. This hole can be filled with either a gaseous or fluid electrolyte, and therefore the working electrode does not have continuous contact with either the transparent window or the current collector. In some embodiments, the working electrode may have indirect or direct full mechanical contact with a partial reflective layer. Advantageously, if there is continuous contact between the working electrode and the transparent window or reflective layer, the position of the working electrode can be inferred using the reflective layer. 【0021】 The electrochemical cells disclosed herein can be constructed without any holes or ports between the working electrode and the transparent window or reflective layer. This is particularly advantageous because the cells of the invention disclosed herein can be more robust and rigid, and can enhance the stability of the structural integrity of the device. 【0022】 Furthermore, the electrochemical cells disclosed herein have continuous contact between the working electrode and the transparent window or reflective layer, which can further simplify the manufacturing process and thus improve cost efficiency. 【0023】 In another aspect of the present invention, an electrochemical cell can be provided. This electrochemical cell comprises a working electrode, a transparent window configured to allow light to reach the working electrode, and a partial reflective layer including one or more regions configured to reflect electromagnetic radiation and one or more regions configured to transmit electromagnetic radiation, wherein the partial reflective layer is in mechanical communication with the working electrode and is configured such that changes therein indicate corresponding changes in the working electrode. 【0024】 Advantageously, since this electrochemical cell is light-reachable, a portion of the working electrode containing the active material particles during the electrochemical process can be imaged in an improved manner. Beneficially, physical changes in the working electrode, such as positional changes due to expansion and contraction during the electrochemical process, result in physical changes in the position of the partial reflective layer, and therefore, physical changes in the reflective interface formed in the partial reflective layer. 【0025】 In one embodiment, changes in the reflective interface can be monitored, for example, to improve imaging of the working electrode during the operation of the electrochemical cell. 【0026】 A partial reflective layer can be positioned, at least partially, between the transparent window and the working electrode. Beneficially, such positioning provides a smooth surface that reflects the reference beam for automatic focusing of the working electrode image during the electrochemical process, and because this surface is very close to the working electrode surface, mechanical communication and imaging improvements are obtained. 【0027】 In some embodiments, automatically focusing the beam position so that the focus remains constant throughout the electrochemical cycle is critical to achieving improved imaging of the working electrode during operation of the electrochemical cell. In some embodiments, the working electrode is in substantial continuous contact with either a transparent window or a partially reflective layer. This can be important to ensure that the reference beam can be directly correlated with the position of the working electrode. 【0028】 The transparent window may be positioned at least partially between the partially reflective layer and the working electrode. Advantageously, such positioning on the outer surface of the transparent window provides advantages in the manufacture of the optically accessible electrochemical cell, the types of materials that can be used for the partially reflective layer, and the range of imaging techniques that can be used to image the working electrode. 【0029】 The partially reflective layer may be at least partially embedded within the working electrode. Advantageously, forming the material of the working electrode layer at least partially in the area between the reflective portions of the partially reflective layer allows the working electrode layer to be in direct mechanical contact with the transparent window. 【0030】 The partially reflective layer can include one or more apertures corresponding to one or more regions configured to transmit electromagnetic radiation, thereby allowing light to reach the working electrode through the partially reflective layer. The partially reflective layer may be a foil layer and / or a mesh layer. Advantageously, the partially reflective surface provides a surface that serves as a reflective reference point for dynamic autofocus while enabling imaging of the working electrode. 【0031】 The electrochemical cell may include one or more layers positioned between the partially reflective layer and the transparent window. Advantageously, the additional layer enhances functionality while facilitating imaging of the working electrode. 【0032】 In one embodiment, the transparent window may include a passivation layer. The passivation layer may be provided in the portion of the transparent window adjacent to the partial reflective layer and the working electrode, so as to be in substantially continuous contact with the partial reflective layer and / or the working electrode. By providing a passivation layer as part of the transparent window, chemical and / or electrochemical changes of the partial reflective layer during the electrochemical cycle due to lithiation and / or redox reactions can be prevented or significantly minimized. 【0033】 In some embodiments, the passivation layer may be optically transparent. In some embodiments, the passivation layer may be electrochemically inert. In some embodiments, the passivation layer may be an oxide, which includes, but is not limited to, silicon dioxide, aluminum oxide, hafnium dioxide, or titanium dioxide. In some embodiments, the passivation layer may be a polymer, which includes, but is not limited to, poly(methyl methacrylate) (PMMA). 【0034】 In some embodiments, the passivation layer may have a thickness of less than 200 nm. In embodiments where the passivation layer is electronically insulating, the reflective layer cannot function as a current collector. 【0035】 Surface roughness can be defined as a measure of how smooth or flat a layer's surface can be. It is typically measured as the difference between peaks and valleys on a given surface. For example, a common method in optical systems is to express the flatness of the surface with respect to the wavelength of light used. A typical mirror exhibits lambda / 10(peak-valley), which in this case could be 80 nm. 【0036】 In one embodiment, the surface roughness of the reflective layer may be less than 100 nm, 90, 80, 70, 60, 50, 40, 30, 20, or 10 nm between peaks and valleys. In another embodiment, the surface roughness of the reflective layer may be 10 nm, 9 nm, 8 nm, 7 nm, 6 nm, 5 nm, 4 nm, 3 nm, 2 nm, or 1 nm between peaks and valleys. 【0037】 In one embodiment, the surface roughness of the working electrode may be between 1 nm and 100 μm, i.e., peak-to-valley intervals of 10 nm, 25 nm, 50 nm, 75 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, or 95 μm. 【0038】 In one embodiment, the thickness of the reflective layer may be less than 200 nm, i.e., less than 190, 180, 170, 160, 150, 140, 130, 120, 110, or 100 nm. In another embodiment, the thickness of the reflective layer may be less than 100 nm, i.e., less than 90, 80, 70, 60, 50, 40, 30, 20, or 10 nm. In yet another embodiment, the thickness of the partial reflective layer may be between 10 and 200 nm, i.e., between 10 and 175 nm, between 10 and 150 nm, between 10 and 125 nm, between 10 and 100 nm, between 10 and 75 nm, between 10 and 50 nm, between 10 and 25 nm, between 10 and 20 nm, or between 10 and 15 nm. 【0039】 If the reflective layer is too thin, for example, less than 5 nm thick, light can partially pass through this thin reflective layer. 【0040】 Furthermore, it will be acknowledged by those skilled in the art that the maximum thickness of the reflective layer can be less than or equal to the surface roughness of the working electrode. The reflective layer must be thick enough to prevent partial transparency and therefore reflect most of the reference beam. The threshold thickness varies depending on the metal, but is typically between 10 nm and 10 nm. 【0041】 In one embodiment, a typical current collector foil that can be used in batteries in the art is often thicker than 15 μm and has a surface roughness greater than 500 nm between peaks. Such a thick reflective layer with large variations is not suitable for use in the present invention. 【0042】 The working electrode may be a self-supporting working electrode or may include a support made of a porous and / or conductive material. Advantageously, the working electrode can be self-supporting and therefore does not require an extra layer. Beneficially, the support made of a porous and / or conductive material provides structural rigidity while allowing electrolyte and light to reach the working electrode. 【0043】 The electrochemical cell may be a coin cell and / or mounted on a printed circuit board. Beneficially, to support improvements in related battery technology, the coin cell can be integrated into a wide range of known systems for performance testing, and light can also be transmitted to it. 【0044】 In yet another aspect of the present invention, an electrochemical cell is provided. This electrochemical cell comprises a working electrode having a channel that is at least partially through, a transparent window configured to allow light to reach the working electrode, and a reflective interface between a portion of the transparent window and a portion of the channel, wherein a change in the reflective interface indicates a corresponding change in the working electrode. 【0045】 An advantage of this electrochemical cell is that, since light can reach it, a portion of the working electrode containing the active material particles during the electrochemical process can be imaged in an improved manner. 【0046】 This electrochemical cell may have a foil layer on the first surface of the working electrode. A transparent window can be configured to allow light to reach a second surface of the working electrode located opposite the first surface. This electrochemical cell may have a foil layer on the first surface of the working electrode, in which case the transparent window is configured to allow light to reach the first surface of the working electrode through one or more apertures in the foil layer. Beneficially, the foil layer provides support for the working electrode without obscuring any portion of the working electrode layer being imaged. 【0047】 In some embodiments, the foil layer may be a current collector and / or a mesh layer. Advantageously, the current collector provides conductivity across the entire portion of the working electrode containing the active material particles. Beneficially, the use of a mesh layer provides channels for the electrolyte to pass through to the active material particles of the working electrode. 【0048】 In one embodiment, the channel may penetrate the working electrode and the foil layer. Beneficially, the channel provides a means for the electrolyte to reach the active material particles while simultaneously providing an interface between the transparent window and the channel. This interface can provide a reflective interface for improving imaging of the working electrode during the electrochemical process. 【0049】 During use, this channel may contain an electrolyte. Advantageously, the electrolyte is supplied to the portion of the working electrode containing the internal active material particles, while also supplying a material with a different refractive index. This material can be used to form an interface that can be used to track changes on the surface of the working electrode. 【0050】 In one embodiment, the working electrode may be mechanically connected to a transparent window. Beneficially, physical changes in the working electrode, such as positional changes due to expansion and contraction during the electrochemical process, result in physical changes in the position of the transparent window. Therefore, monitoring the reflective interface formed between the channel through the working electrode and the transparent window allows for improvements to the imaging of the working electrode during the operation of the electrochemical cell. 【0051】 In one embodiment, the working electrode may contain an active material, and the active material loading of the working electrode may be at least 80%. 【0052】 Another aspect of the present invention also provides a method for imaging a working electrode through a transparent window in at least part of an electrochemical process. This method includes the steps of: monitoring reflection in a partial reflective layer mechanically communicating with the working electrode; imaging a portion of the working electrode for at least part of the electrochemical process using an imaging device; determining a change in reflection in the partial reflective layer; and adjusting the imaging focus of the imaging device in response to the determination of the change, wherein the step of monitoring reflection includes directing a reference beam toward one of one or more regions of the partial reflective layer configured to reflect electromagnetic radiation; and the step of imaging a portion of the working electrode includes imaging through one or more regions of the partial reflective layer configured to transmit electromagnetic radiation, wherein the working electrode is in substantially continuous contact with either the transparent window or the partial reflective layer. 【0053】 In yet another aspect of the present invention, a method for imaging a working electrode during at least a portion of an electrochemical process can also be provided. This method includes the steps of: monitoring reflection in a partial reflective layer mechanically communicating with the working electrode; imaging a portion of the working electrode during at least a portion of the electrochemical process using an imaging device; determining a change in reflection in the partial reflective layer; and adjusting the imaging focus of the imaging device in response to the determination of a change, wherein the step of monitoring reflection includes directing a reference beam toward one of one or more regions of the partial reflective layer configured to reflect electromagnetic radiation, and the step of imaging a portion of the working electrode includes imaging through one or more regions of the partial reflective layer configured to transmit electromagnetic radiation. 【0054】 An advantage is that it provides an improved system that allows for stable imaging while the working electrode is in operation. 【0055】 In another aspect of the present invention, a method for imaging a working electrode during at least a portion of an electrochemical process can also be provided. This method includes the steps of: monitoring reflection at the interface between a transparent window and a channel that at least partially penetrates the working electrode; imaging a portion of the working electrode during at least a portion of the electrochemical process using an imaging device; determining a change in reflection at the interface; and adjusting the imaging focus of the imaging device in response to the determination of the change. 【0056】 During use, the channel may contain an electrolyte. Advantageously, the electrolyte is supplied directly to a portion of the working electrode containing the active material particles, while also functioning as part of a reflective interface that can be used as part of a feedback mechanism for stable imaging of the working electrode during its use. 【0057】 In one embodiment, the step of imaging a portion of the working electrode may include the step of imaging a first surface of the working electrode located opposite the second surface of the working electrode, and the working electrode includes a foil layer on the second surface. Advantageously, the foil provides support and uniform conductivity without interfering with the optical inspection of the working electrode. 【0058】 The step of imaging a portion of the working electrode may include the step of imaging a first surface of the working electrode, wherein the working electrode includes a foil layer having one or more apertures on its first surface. Advantageously, this foil provides support without interfering with the optical inspection of the working electrode. 【0059】 In one embodiment, the step of monitoring reflection may include the step of guiding a reference beam to the interface and the step of detecting the position and / or intensity of the reflected reference beam. In one embodiment, the step of monitoring reflection may include the step of detecting the position and / or intensity of the reflected reference beam. Beneficially, changes in the reflection of the reference beam indicate changes in the working electrode, which allows for adjustment when imaging the working electrode. 【0060】 In one embodiment, the step of adjusting the imaging focus may include a step of compensating for a partial position change of the working electrode in a direction substantially perpendicular to the focal plane by dynamically changing the focal plane of the imaging device. Beneficially, this can improve the stability of the imaging focus during the electrochemical process. 【0061】 Furthermore, this specification also provides a method for preparing an imaging system for imaging a working electrode during at least a portion of an electrochemical process, according to the method described herein. 【0062】 A method for preparing an imaging system may include the steps of forming a partial reflective layer on a transparent window, and then bringing the transparent window, together with the partial reflective layer, into substantially continuous contact with the working electrode. 【0063】 In one embodiment, a method for preparing the imaging system may include the steps of forming a partial reflective layer on a transparent window, and then bringing the transparent window, together with the partial reflective layer, into substantially continuous contact with the working electrode. Advantageously, the transparent window is used to provide a smooth surface on the partial reflective layer, enabling the formation of a thin layer that properly mechanically communicates with the working electrode. 【0064】 In one embodiment, the method for preparing the imaging system may include the step of forming a channel that at least partially penetrates the working electrode. Advantageously, the channel allows the electrolyte to reach the active material particles of the working electrode, while providing means for forming an interface to monitor reflections from a reference beam. These reflections indicate changes in the working electrode, and these changes can be compensated for during imaging. 【0065】 In one embodiment, the step of forming channels may be achieved by forming working electrodes on a foil mesh or woven wire mesh containing one or more channels. In another embodiment, channels are formed by perforating a foil layer and forming working electrodes on the perforated foil layer. 【0066】 In one embodiment, instead, a working electrode is formed on a foil layer, and then channels are formed by perforating the working electrode. Beneficially, a conventional working electrode can be modified to suit a photoreaching electrochemical cell, or a commercially available mesh or modified foil can be provided, and then active material particles can be molded onto these to create channels having the advantages described herein. 【0067】 In some embodiments, the drilling step may include the use of at least one of mechanical drilling, laser drilling, and laser cutting. Beneficially, mechanical drilling is a simple and effective method for modifying existing material. Beneficially, laser drilling and laser cutting allow for fine control in creating a uniform channel through the working electrode. 【0068】 Furthermore, a system for imaging the working electrode during at least part of an electrochemical process can also be provided. This system comprises an imaging device including a light source, and the system is configured to perform the method described herein. 【0069】 This system may also include an electrochemical cell in accordance with the electrochemical cell described herein. 【0070】 This system may be equipped with electrical connections for accepting electrochemical cells such as batteries. 【0071】 In one embodiment, the system may include electrical connections for receiving battery electrodes. 【0072】 The light source may include, but is not limited to, at least one of the following: a laser, a light-emitting diode, and a lamp. And / or, the imaging device may include an optical microscope. 【0073】 Further aspects of the present invention will also be apparent from the description and the appended claims. 【0074】 The present invention will now be described more specifically and in more detail, using only one example and with reference to the attached drawings. [Brief explanation of the drawing] 【0075】 [Figure 1A] Following prior art, this document presents a system for analyzing the electrochemical behavior of diluted battery electrodes using interference scattering. [Figure 1B] A cross-sectional view of an electrochemical coin-type cell based on prior art is shown. [Figure 2] A cross-sectional view of the photoreach electrochemical cell and optical imaging system is shown. [Figure 3] This diagram shows the process flow for imaging the working electrode during an electrochemical process. [Figure 4] Alternative embodiments of photoreach electrochemical cells and optical imaging systems are shown. [Figure 5] A cross-sectional view of an alternative light-reaching electrochemical cell is shown. [Figure 6] A cross-sectional view of an alternative light-reaching electrochemical cell is shown. [Figure 7] A cross-sectional view of an alternative light-reaching electrochemical cell is shown. [Figure 8A] This shows an optical device that enables automatic focusing. [Figure 8B] This shows the monitoring of reflections from the reference beam. [Figure 9] A cross-sectional view of the photoreach electrochemical cell and optical imaging system is shown. [Figure 10A] This shows an optical device that enables automatic focusing. [Figure 10B] This shows the monitoring of reflections from the reference beam. [Figure 11A] A series of cross-sectional images are shown as part of the process of forming the working electrode. [Figure 11B] A series of cross-sectional images are shown as part of the process of forming the working electrode. [Figure 12A] A series of cross-sectional images are shown as part of the process of forming the working electrode. [Figure 12B] A series of cross-sectional images are shown as part of the process of forming the working electrode. [Figure 13A] A series of cross-sectional images are shown as part of the process of forming the working electrode. [Figure 13B] A series of cross-sectional images are shown as part of the process of forming the working electrode. [Modes for carrying out the invention] 【0076】 As mentioned above, known methods for optically imaging electrochemical cell electrodes during real-time operation are not suitable for application to conventional electrochemical cell electrodes. Figure 2 shows a cross-sectional view of a photoreaching electrochemical cell 300, which forms part of a system for imaging the working electrode layer 306 of the electrochemical cell 300 during the electrochemical process. Advantageously, the arrangement described with reference to Figure 2 enables optical imaging of conventional electrochemical cell electrodes during real-time operation. This explanation will help to deepen our understanding of the processes that occur during operation in such conventional electrodes and, therefore, the problems that can be addressed to develop such technologies. 【0077】 The electrochemical cell 300 comprises a cell housing 302. In the illustrated orientation, this is the lower cell housing 302 (the electrochemical cell 300 can be oriented in any convenient direction during use). The lower cell housing 302 has an aperture 303 that allows light to reach inside the electrochemical cell 300, in contrast to the opaque, apertureless housing 202 of the prior art electrochemical coin cell 200 described with reference to Figure 1B. There is a transparent window 320 that allows light to reach inside the electrochemical cell 300 while sealing the aperture 303. The transparent window 320 is a glass coverslip fixed to the inside of the cell housing 302 using thermoplastic plastic to form a seal. The glass coverslip is about 170 microns thick and has a diameter of about 12 mm. The aperture 303 is circular with a diameter of 6 mm. In other embodiments not shown, the aperture 303 may have a different shape and size, but still allow light to reach inside the electrochemical cell 300. In further, not-illustrated embodiments, the transparent window 320 is formed of a different material having the same or different thickness and / or diameter, so as to allow light to reach the working electrode of the electrochemical cell 300, and such material is optically transparent at the wavelength of light used to image the working electrode. In yet another, not-illustrated embodiment, the transparent window is instead mounted on the outside of the cell housing 302, or at least partially within the thickness of the cell housing 302. While it has been described that the transparent window 320 is mounted to the cell housing 302 using thermoplastic plastic, in other examples, additional and / or alternative materials and / or techniques are used to mount the transparent window 320 to the cell housing 302. 【0078】 Above the transparent window 320, the working electrode layer 306 is shown. The working electrode layer 306 is a conventional working electrode layer in which high-density active material particles are molded on the current collector layer 319. The working electrode layer 306, including the active material particles and the current collector layer 319, together form the working electrode. The current collector layer 319 is a conductive layer and is permeable to the liquid electrolyte material. In one example, the current collector layer 319 is a mesh layer, such as a metal mesh layer. In another example, the current collector layer 319 contains carbon paper. In yet another example, the current collector layer 319 is porous to allow electrical conduction between the working electrode layer 306 and the cell housing 302, and to allow the liquid electrolyte to reach the working electrode layer 306, and is composed of any suitable material and structure that allows the liquid electrolyte to pass through in the electromechanical cell 300. 【0079】 In yet another example, the current collector layer 319 may be omitted, and the working electrode may be formed solely from the working electrode layer 306 and be self-supporting. Alternatively, the working electrode may be formed from a combination of the working electrode layer 306 and one or more other layers, such as a foil layer. 【0080】 A conductive mesh 318 is shown above the working electrode layer 306 and is electrically connected to the lower cell housing 302. The conductive mesh 318 is a mesh made of aluminum, copper, or stainless steel and has open holes of different sizes, such as 1 mm in diameter, and narrow ribbons of aluminum metal with a width of 140 microns. 【0081】 Figure 2 shows a conductive mesh 318, but in other examples not shown, the conductive mesh 318 is not included. For example, the working electrode layer 306 may be in direct electrical contact with the cell housing 302. Alternatively and / or in addition, the transparent window 320 may be at least partially conductive, thereby providing conductivity between the working electrode layer 306 and the cell housing 302. 【0082】 In other examples not shown, additional and / or alternative materials may be used to provide electrical connections to the cell housing 302. 【0083】 The working electrode layer 306 contains active material particles. In one example, the active material contains lithium cobalt oxide (LCO). In another example, the active material contains nickel-manganese-cobalt mixed oxide (NMC). In yet another example, the working electrode layer 306 contains any suitable electrochemical cell material. In addition, in some examples, the working electrode layer 306 also contains additional materials, such as conductive additives and / or binder materials. 【0084】 The working electrode layer 306 has a circular surface with a diameter of 10 mm and is formed on the current collector layer 319. The current collector layer 319 is a circular mesh made of aluminum, copper, or stainless steel with a thickness of 20 microns. In yet another example, the working electrode is formed from working electrode layers 306 and current collector layers 319 of different shapes and / or diameters. 【0085】 The partial reflective layer 304 is located on the side of the transparent window 320 opposite to the working electrode layer 306, creating one or more reflective regions between the transparent window 320 and one or more regions of the working electrode layer 306 and the partial reflective layer 304, through which light reaches the working electrode layer 306. The partial reflective layer 304 is a metallic layer that covers only a portion of the glass surface of the aperture 303, allowing imaging of the working electrode layer 306 in the uncovered regions. The uncovered regions correspond to one or more regions of the partial reflective layer 304 configured to transmit electromagnetic radiation. In one example, the reflective layer 304 is formed from at least one of gold, aluminum, platinum, and copper. In yet another example, the partial reflective layer 304 is formed from any material that provides the functions described herein. 【0086】 In one example, the partial reflective layer 304 is formed by patterning a metal layer on a transparent window 320. The metallic partial reflective layer 304 is patterned using sputtering or metal deposition. The patterning of the partial reflective layer 304 is carried out such that the layer has one or more reflective regions and one or more transmissive regions, allowing the working electrode 306 to be imaged through the transmissive regions, and providing areas where the reflective regions are mechanically in communication with the working electrode layer, allowing the reference reflected beam to be monitored from these areas. The patterning can take any suitable configuration and is carried out by any suitable means, such as by physical masking and / or photolithography. The partial reflective layer 304 may be continuous or discontinuous and provide one or more substantially reflective regions and one or more substantially transmissive regions. In one example, the substantially transmissive regions correspond to areas where there is no reflective material deposited. The planar area and shape of the partial reflective layer 304 may be the same as or different from the planar area and shape of the working electrode layer 306. For example, the partial reflective layer 304 may be positioned to cover any applicable area of ​​the working electrode layer 306, while including reflective regions that allow light to reach any applicable area of ​​the working electrode layer 306. While the partial reflective layer 304 is a patterned layer, in other examples, the partial reflective layer 304 may be formed, either by or in addition, by using one or more pre-formed substantially light-reflective and / or light-transmitting structures. Thus, the optically reflective structures serve as reference markers, enabling the autofocus function described herein. 【0087】 In one example, a transparent window 320 made of glass is coated with a 50 nm thick platinum layer to provide a smooth surface with high reflectivity (50 nm of platinum gives a reflectivity of >90%). In yet another example, a partially reflective layer 304 made of metal is formed from any suitable material having an appropriate thickness to provide the functions described herein. 【0088】 In yet another example, the metallic partial reflective layer 304 is provided by painting or marking the surface of the transparent window 320 with a conductive paint such as Ag paint, or by using a metallic marker pen. In yet another example, the metallic partial reflective layer 304 is provided by any suitable technique. 【0089】 The interface between the partial reflective layer 304 and the transparent window 320 defines a sharp, flat interface that contributes to active focus stabilization. This interface is, in some cases, a metal-glass interface and is smooth and constant in contrast to the relatively rough and inconsistent surface of the working electrode layer 306. 【0090】 The working electrode layer 306, which contains active material particles, is positioned so that the active material particles are visible in one or more regions 322 through the transparent window 320. The one or more regions 322 in which the active material particles are visible may be associated with a separation between the working electrode layer 306 and the transparent window 320, as shown in Figure 2. In yet another example, at least one or more materials are filled in the lateral gaps between regions of the partial reflective layer 304 and the space associated with the longitudinal separation between the working electrode layer 306 and the transparent window 320. This space may include, for example, multiple portions of the working electrode layer 306. The working electrode layer 306 containing the active material particles is pressed against the inner surface of the transparent window 320, which is patterned with the partial reflective layer 304, so that the working electrode layer 306 and the transparent window 320 are in mechanical communication. In yet another example, there are one or more other layers between the working electrode 306 and the transparent window 320 so as to maintain the functions described herein. 【0091】 In one example, the partial reflective layer 304 is formed on the transparent window 320 before being mechanically connected to the working electrode layer 306. In yet another example, the partial reflective layer 304 is formed on the working electrode layer 306 before being mechanically connected to the transparent window 320. When the partial reflective layer 304 is formed on the working electrode layer 306, it is mechanically connected to the working electrode layer 306. In yet another example, the partial reflective layer 304 is provided by introducing a separation layer between the transparent window 320 and the working electrode layer 306. For example, a metal mesh layer placed between the working electrode layer 306 and the transparent window 320 provides a smooth reflective surface for reference reflection while allowing light to reach the working electrode layer 306 during operation. 【0092】 The partial reflective layer 304 is shown to have multiple regions 322 that allow optical inspection of the working electrode layer 306 through a transparent window 320. 【0093】 The partial reflective layer 304 formed on the transparent window 320 defines a sharp, flat surface that can be used as a reference reflective interface for imaging focus stabilization, as described herein. Since the working electrode layer 306 is mechanically bonded to the transparent window 320, positional changes of the partial reflective layer 304 formed on the transparent window 320 allow for tracking of corresponding changes on the surface of the working electrode layer 306 in the vicinity of the partial reflective layer 304, thereby providing input for adjusting the imaging focus of the working electrode layer 306 in the event of any positional changes of the working electrode layer 306 (e.g., due to expansion / contraction during the operation of the electrochemical cell 300). Such changes indicate the behavior of the working electrode layer 306 and can be used to communicate the adjustment of the imaging focus of a portion of the working electrode layer 306 during the electrochemical process. 【0094】 In Figure 2, above the conductive mesh layer 318, separators 308, counter electrode 310, spacer 312, and spring 314 are shown, corresponding to the separator 208, counter electrode 210, spacer 212, and spring 214 described in relation to the prior art conventional electrochemical coin cell 200 shown in Figures 1A and 1B. Separator 308 is a glass fiber separator, and spacer 312 is a stainless steel spacer. Further, in other examples not shown, additional and / or alternative layers and / or components may be implemented. 【0095】 The stack of layers inside the electrochemical cell 300 is moistened with an electrolyte. In one example, 200 μl of LP57 electrolyte is used. In yet another example, different amounts and / or types of electrolytes are used, including, for example, a solid electrolyte (SSE). The layers inside the electrochemical cell 300 are sealed inside the electrochemical cell 300 by being enclosed by the upper cell housing 316. Light can reach the working electrode layer 306 through a transparent window 320 created in the aperture 303 of the lower cell housing 302. 【0096】 While the electrochemical cell 300 has been described in relation to specific layers formed in a particular order, in other examples, additional, fewer, and / or alternative layers and / or components may also be used to provide a light-reaching electrochemical cell in accordance with the claimed invention. For example, in another example, the working electrode is a self-supporting electrode layer that does not include the current collector layer 319. In yet another example, the working electrode includes a foil layer on the surface of the working electrode 306 located between the transparent window 320 and the working electrode layer 306. In such a configuration, the foil layer comprises one or more apertures, which allow light to reach the working electrode layer 306 through the foil layer so as to image the working electrode layer 306 in accordance with the method described herein, by exposing the corresponding portion of the working electrode layer 306. In such a case, the foil layer may be a partially reflective layer 304. 【0097】 The cell housings 302 and 316 form a coin-type cell housing, such as a modified CR2032 coin-type cell housing. In other examples, the electrochemical cell 300 has a different coin-type cell configuration. In yet another example, the electrochemical cell 300 is a different type of cell, such as a pouch cell or a Swagelok (RTM) type cell, with similarly arranged internal components to obtain the advantages described herein. 【0098】 The electrical connections made to the upper cell housing 316 and the lower cell housing 302 facilitate the application of current-voltage states, such as charging and discharging states, which cause electrochemical processes to occur inside the electrochemical cell 300. Such electrochemical processes can be imaged by imaging a portion of the working electrode layer 306 that can be reached by light through the transparent window 320. 【0099】 Advantageously, the entities within the electrochemical cell 300 are arranged so that the electrolyte can reach the active material of the working electrode layer 306, thereby facilitating improved imaging, as described herein. Furthermore, the electrochemical cell 300 is relatively cost-effective, easy to assemble, can be integrated into root battery testing, and provides a significant improvement in circulating behavior compared to known cells. 【0100】 The working electrode layer 306 is imaged using the imaging device 328. The imaging device 328 includes a light source 330 that supplies light for illumination / imaging in the direction indicated by the arrow 326. This light source is a 530 nm light-emitting diode (LED). In other examples, alternative and / or additional light sources, such as laser diodes, lamps, and / or LEDs with different peak wavelengths, are also used for illumination / imaging the working electrode layer 306. 【0101】 To image the working electrode layer 306, the electrochemical cell 300 is held in a suitable location, such as part of the sample stage. In one example, the imaging device 328 receives the electrochemical cell 300 and provides a fixed position for making electrical connections to the electrodes of the electrochemical cell 300 so that appropriate current-voltage conditions can be applied while imaging the working electrode layer 306. 【0102】 Light source 330 directs light through an optical microscope to a portion of the working electrode that is visually exposed, and is positioned so that this portion of the working electrode 306 is imaged. The optical microscope comprises a lens system 332, a polarizing beam splitter 334 or beam splitter, a quarter-wave plate 336, and an objective lens 338. The light scattered by its portion of the working electrode layer 306 is then directed through the objective lens 338 and the quarter-wave plate 336, and through the beam splitter 334, through the lens system 340, to reach the camera 342, where an image of its portion of the working electrode layer 306 is captured. 【0103】 While the optical microscope has a specific configuration for imaging the working electrode layer 306, other examples may incorporate alternative and / or additional optical components to obtain focused images of a portion of the working electrode layer 306 during the electrochemical process. 【0104】 The imaging device 328 communicates with the computing device 352 via a communication channel 346 located between the interface 344 of the imaging device 328 and the interface 358 of the computing device 352. The computing device 352 comprises a processor 354 and memory 356. The computing device 352 communicates with the network 360 via a communication channel 350 located between the computing device 352 and the network 360. The imaging device 328 also communicates with the network 360 via the communication channel 348 and the interface 344 of the imaging device 328. 【0105】 The computing device 352 communicates with the autofocusing device 900. The autofocusing device 900 is described in more detail with reference to Figure 8. The autofocusing device 900 is used to induce and measure the reflection of the reference beam 324 from the partial reflection layer 304 formed in the photoreaching electrochemical cell 300. 【0106】 While the imaging device 328 and autofocus device 900 are shown to communicate with a computing device 352 and a network 360, in other embodiments not shown, the imaging device 328 and autofocus device 900 are implemented and controlled in any suitable manner according to the techniques described herein. In one example, the computing device 352 is integrated with the imaging device 328 and / or autofocus device 900. 【0107】 During imaging of a portion of the working electrode layer 306, it is important to maintain focus on the surface of the portion of the working electrode layer 306 that is being imaged. The computing device 352 communicates with the imaging device 328 and the autofocus device 900 and is configured to dynamically control the relative positions of the optical components of the imaging device 328 and / or the electrochemical cell 300 of the imaging device 328. 【0108】 To maintain focus on a portion of the working electrode layer 306 that is the target of imaging, the focal plane of the optical device is adjusted to be substantially perpendicular to the portion of the working electrode layer 306 (it may also be substantially perpendicular to the flat surface of the working electrode layer 306 adjacent to the transparent window 320). In Cartesian coordinates where the flat surface of the working electrode layer 306 lies in a plane substantially defined by the x and y axes, the focal plane of the optical device is adjusted along the z axis to obtain a focused image of a portion of the working electrode layer 306. 【0109】 In the initial state, focusing on a portion of the working electrode layer 306 is sufficient by changing the relative position of the focal plane perpendicular to the z-axis so that a portion of the working electrode layer 306 coincides with the focal plane of the optical device 328. However, during the real-time operation of the electrochemical cell 300, the application of current-voltage conditions may cause a portion of the working electrode layer 306 to change and no longer coincide with the focal plane. Such changes may result from expansion or contraction of the working electrode layer 306 during operation, changes in the refractive index of the electrolyte inside the electrochemical cell 300 during operation, and changes due to the oscillation of the sample stage supporting the electrochemical cell during operation. 【0110】 As mentioned above, the high density of the active material in conventional electrochemical cell electrodes means that the surface is rough and, as in the case of dilution electrochemical cell electrodes, unsuitable for use as a reference point to maintain focal stability. In dilution electrochemical cell electrodes, a reference light beam of a suitable spot size is positioned on a relatively smooth, inert surface between the active particles so that changes in the z position of the dilution electrode can be tracked. Advantageously, the smooth window surface, usually made of glass, allows the patterned partial reflective layer 304 on the transparent window 320 to work effectively, forming a very thin partial reflective layer 304 adjacent to the working electrode layer 306, enabling good mechanical communication between the transparent window 320 and the working electrode layer 306. In addition, the reflective region of the thin partial reflective layer 304 provides a reference point for reference reflections that can be used to monitor changes in the working electrode layer 306. As a result of the changes in the working electrode layer 306, a change occurs in the relative position difference between a portion of the working electrode layer 306 that is the target of imaging and the focal plane of the optical device 328 used to image the portion of the working electrode layer 306. 【0111】 Figure 3 shows the process flow S400 for imaging a portion of the working electrode layer 306 of the photoreaching electrochemical cell 300 during an electrochemical process. Process flow S400 is performed using the imaging device 328 described with reference to Figure 2, and / or in other embodiments referred to when describing the provision of similar or identical functionality for imaging a portion of the working electrode layer 306 of the photoreaching electrochemical cell 300. Process flow S400 is controlled using the computing device 352 described with reference to Figure 2. The computing device 352 is used to control the imaging process directly by controlling the imaging device 328, and / or indirectly through the computing network 360. 【0112】 This process begins in the first step S402, proceeds to step S404, and images a portion of the working electrode layer 306. This process may also be initiated by the user identifying the portion of the working electrode layer 306 to be imaged and starting an experiment to perform an electrochemical process in the electrochemical cell 300, while simultaneously imaging the portion of the working electrode layer 306 and automatically maintaining focus on the portion of the working electrode layer 306 being imaged. 【0113】 To image a portion of the working electrode layer 306, the imaging device 328 is positioned so that the portion of the working electrode layer 306 is illuminated by light, as indicated by arrow 326 in Figure 2. The working electrode layer 306 is imaged through the transparent region of the partial reflective layer 304. The imaging focus of the imaging device 328 is adjusted so that the focal plane of the imaging device 328 coincides with the portion of the working electrode layer 306 to be imaged. The electrochemical process is initiated by applying the corresponding current-voltage state to the electrodes 306, 310 of the electrochemical cell 300. 【0114】 One example of an electrochemical process is charging and discharging an electrochemical cell 300 using a CC CV-CC CV cycling protocol at a constant current (CC) rate of C / 5 (nominal 5-hour charge (discharge) time) and a constant voltage (CV) of 1 hour. Other examples will induce different electrochemical processes. 【0115】 Next, the process proceeds to step S406 to determine whether imaging is complete or not. The determination of whether imaging is complete or not is made at the discretion of the user, or, instead and / or in addition, by the control of the imaging device 328 based on computer implementation instructions executed by the computing device 352, for example, by the control of the imaging device 328 based on computer implementation instructions stored in the memory 356 of the computing device 352. 【0116】 If imaging is not yet complete, the process moves to step S408, where the reference reflection is monitored. The reference reflection is monitored by a combination of the computing device 352 and the imaging device 328. In one example, the computing device 352 is integrated with the imaging device 328. The computing device 352 is configured to implement a hardware or software feedback protocol, for example, a proportional-integral-derivative (PID) control system, and to have an input based on monitoring the reflection of the reference beam processed by the processor 354 to determine the focusing control of the imaging device 328. Imaging and focusing can be performed sequentially or in parallel. For example, the imaging device 328 may continue to capture images of a portion of the working electrode layer 306, while the autofocus device 900 simultaneously monitors the reference reflection so that the computing device 352 adjusts the imaging and focusing in any suitable way. 【0117】 The reference reflection is monitored by directing focusing radiation toward the reflective region of the partial reflective layer 304 formed on the transparent window 320. Advantageously, the partial reflective layer 304 provides a means of obtaining a clear and consistent reflection, and this reflection is inseparably linked to the working electrode layer 306 such that changes in the reflection in the partial reflective layer 304 indicate changes in the working electrode layer 306. This means that, for example, if the working electrode layer 306 changes during operation, such as when a portion of the object being imaged moves and moves out of the focal plane of the imaging device 328, the change in reflection at the reflective interface is used as input to compensate for this change by adjusting the focal plane of the imaging device 328 in a z-direction substantially perpendicular to the flat surface of the portion of the working electrode layer 306 that is being imaged, thereby maintaining a stable focus. 【0118】 To monitor the reference reflection, the optical device 900, as described with reference to Figures 8A and 8B, is used in combination with the computing device 352 and / or the imaging device 328. 【0119】 Figure 8A shows an optical device 900A controlled by a computing device 352 that enables automatic focusing of the imaging device 328, illustrating the principle of using a reference beam reflected at a reflective interface, such as between the transparent window 320 and the partial reflective layer 304, to determine changes in reflection and compensate for those changes accordingly. 【0120】 A reference beam 902 from a light source is shown, which passes through a focusing lens 916, through a mirror 918, through an objective lens 920, and is guided to focus at a reflective interface between a transparent window 320 and a partial reflective layer 304. The light source is a parallelized low-power laser beam with a wavelength of 785 nm. In other examples, any suitable light source of wavelength, power, and / or type can be used to supply the reference beam. 【0121】 As indicated by arrow 324 in Figure 2, the reference beam is guided toward the reflective interface between the transparent window 320 and the partial reflective layer 304. Advantageously, the partial reflective layer 304 is a thin layer, which provides excellent mechanical communication with the working electrode layer 306 while simultaneously providing a reference point for determining any changes that may alter the imaging focus of the working electrode layer 306. 【0122】 The example in Figure 8A shows a transparent window 320 such that the reflection interface between the transparent window 320 and the partial reflection layer 304 is at a first position 910. The reference beam 902 is focused at the interface between the transparent window 320 and the region of the partial reflection layer 304 at the first position 910. The reference beam 902 is focused to form a focus spot at the reflection interface, with a Gaussian full width at half maximum of 5 to 15 microns. In other examples, different spot sizes are used to monitor changes at the reflection interface. 【0123】 The first reflected beam 904 from the reflective interface between the transparent window 320 and the partial reflective layer 304 at the first position 910 is guided through the objective lens 920 and the cylindrical lens 922 to reach the camera 924. Here, the first reflected beam 904 appears as a reflected line at the first position 904', as shown in the projection 900B of the xy-plane of the reference beam image captured by the camera 924 in Figure 8B. 【0124】 When the transparent window 320 moves in the z direction 912 and the reflection interface between the transparent window 320 and the partial reflection layer 304 reaches the second position 910', there is a change corresponding to the reflection of the reference beam 902. At the second position 910', the second reflected beam 906 from the reflection interface formed by the transparent window 320 and the partial reflection layer 304 appears as a reflection line at the second position 906', as shown in the projection 900B of the reference beam image captured by the camera 924 in Figure 8B. 【0125】 The z-direction 912 corresponds to a direction substantially perpendicular to the flat surface of the working electrode layer 306. Such positional changes of the working electrode layer 306 occur, for example, due to the expansion or contraction of the electrode under operating conditions. 【0126】 As the reflective interface between the transparent window 320 and the partial reflective layer 304 moves from the second position 910' to the third position 910'', there is a change corresponding to the reflection of the reference beam 902. At the third position 910'', the third reflected beam 908 from the reflective interface formed by the transparent window 320 and the partial reflective layer 304 appears as a reflection line at the third position 908', as shown in the projection 900B of the reference beam image captured by the camera 924 in Figure 8B. 【0127】 As shown in Figure 8A, the lateral positions of the reflected beams 904, 906, and 908 change in the lateral direction 914 in the xy-plane. These changes are perpendicular to the z-direction movement of the reflective interface between the transparent window 320 and the partial reflective layer 304, and are a function of the position of the reflective interface between the transparent window 320 and the reflective layer 304. Therefore, by monitoring the reflection of the reference beam, changes in reflection at the reflective interface can be determined and the corresponding changes in the working electrode layer 306 can be taken into account. 【0128】 The configurations of the autofocus optics 900A and 900B, described with reference to Figures 8A and 8B, monitor reflections so that these reflections appear as lines in the camera 924. In other examples, additional and / or alternative detections are used on the reflection being monitored to determine changes in the position of the interface between the transparent window 320 and the reflective layer 304, based on the position and intensity changes detected from monitoring the reflections. 【0129】 With respect to Figures 8A and 8B, a specific configuration of optical components for monitoring the reflection of a reference beam has been described; however, in other examples, additional and / or alternative optical components may be used to provide the functions described herein. 【0130】 Next, the process proceeds to step S410, where it is determined whether the reference reflection has changed at the interface between the transparent window 320 and the partial reflective layer 304. If the reference reflection has not changed, the process proceeds to step S404, where the imaging device 328 images a portion of the working electrode layer 306 again. If it is determined in step S406 that imaging has finished, the process ends in step S414. 【0131】 If it is determined in step S410 that the reference reflection has changed, the process moves to step S412, where the change during the electrochemical process is compensated for by adjusting the imaging focus of a portion of the working electrode. Since the change in the reflection of the reference beam at the reflection interface between the transparent window 320 and the partial reflection layer 304 fluctuates as a function of the corresponding change in the working electrode layer 306, the focal plane of the imaging device 328 is adjusted based on the change in reflection at the reflection interface to compensate for the difference between the position of the focal plane and the portion of the working electrode layer 306 that is being imaged. 【0132】 The imaging and monitoring steps of process flow S400 are repeated for the desired operating period of the electrochemical cell 300 under investigation. While specific steps are shown in process flow S400, it will be understood by those skilled in the art that additional and / or alternative steps may be performed in other (not illustrated) embodiments, while providing the functionality described herein. In other embodiments, the steps of process flow S400 may be performed simultaneously or sequentially in any manner to provide the functionality to adjust the imaging of the working electrode in response to the determination of changes in the reference beam reflected at the reflective reference interface described herein. 【0133】 An advantage is that the electrochemical cell 300, as described with reference to Figure 2, is configured to allow real-time monitoring of a portion of the working electrode in an improved manner. The frequency of imaging and adjustment of the imaging focus can be changed to determine the desired data. 【0134】 Figure 4 shows an alternative embodiment of the photoreaching electrochemical cell and imaging system shown in Figure 2. Figure 4 shows a cross-sectional view of the photoreaching electrochemical cell 300, which forms part of a system for imaging the working electrode layer 306 of the electrochemical cell 300 during an electrochemical process. 【0135】 As shown in Figure 4, in this embodiment, the transparent window 320 includes a passivation layer 321. The passivation layer 321 is provided in the portion of the transparent window 320 adjacent to the partial reflective layer 304 and / or the working electrode 306 to obtain substantially continuous contact with them. By incorporating the passivation layer 321 into the transparent window 320, chemical and / or electrochemical changes in the partial reflective layer 304 are prevented by preventing contact of electrons and / or ions with the partial reflective layer 304. The passivation layer 321 is optically transparent and also electronically insulating. The passivation layer 321 may be made of an oxide including, but not limited to, silicon dioxide, aluminum oxide, hafnium dioxide, or titanium dioxide. The passivation layer may also be a polymer including, but not limited to, poly(methyl methacrylate) (PMMA). The passivation layer may have a thickness of less than 200 nm. 【0136】 As schematically shown in Figure 4, the imaging device 328 communicates with the computing device 352 via a communication channel 346 located between the interface 344 of the imaging device 328 and the interface 358 of the computing device 352. The computing device 352 comprises a processor 354 and memory 356. The computing device 352 communicates with the network 360 via a communication channel 350 located between the computing device 352 and the network 360. The imaging device 328 also communicates with the network 360 via the communication channel 348 and the interface 344 of the imaging device 328. 【0137】 The example configuration of the electrochemical cell 300 shown in Figure 2 offers numerous advantages in improving the imaging of the working electrode layer 306 during the electrochemical process due to the excellent mechanical communication between the reference interface between the partially reflective layer 304 and the working electrode layer 306, adjacent to the region 322 related to the arrival of light to the working electrode layer 306 through the transparent window 320. However, similar functionality can be achieved by forming reflective interfaces in alternative ways, as shown with reference to the examples in Figures 5-7. The electrochemical cells 500, 600, 700, and 800 described with reference to Figures 5-7 are used in the implementation of process S400 described with reference to Figure 3. In further examples, the electrochemical cells 500, 600, 700, and 800, and their alternative configurations, can also be implemented in any way that provides the functionality described herein. 【0138】 Figure 5 shows a cross-sectional view of the electrochemical cell 500. In the example of Figure 5, the electrochemical cell 500 has components equivalent to those shown for the electrochemical cell 300 shown in Figure 2. For example, the electrochemical cell 500 includes a cell housing 502, which is the lower cell housing 502 in the illustrated orientation (the electrochemical cell 500 can be oriented in any convenient direction during use). The lower cell housing 502 has an aperture 503 that allows light to reach inside the electrochemical cell 500, in contrast to the opaque, apertureless housing 202 of the prior art electrochemical coin cell 200 described with reference to Figure 1B. There is a transparent window 520 that allows light to reach inside the electrochemical cell 500 while sealing the aperture 503, as described with reference to the transparent window 320 in Figure 2. Above the transparent window 520, the working electrode is shown, including the working electrode layer 506 and the current collector layer 519. A conductive mesh 518 is shown above the working electrode and is electrically connected to the lower cell housing 502. Above the conductive mesh layer 518, in Figure 5, a separator 508, a counter electrode 510, a spacer 512, and a spring 514 are shown, which correspond to the separator 308, counter electrode 310, spacer 312, and spring 314 described in relation to the electrochemical coin cell 300 in Figure 2. 【0139】 In contrast to the electrochemical cell 300 shown in Figure 2, the electrochemical cell 500 in Figure 5 shows a partial reflective layer 504 embedded within the working electrode layer 506. The partial reflective layer 504 includes one or more regions configured to reflect electromagnetic radiation and one or more regions configured to transmit electromagnetic radiation. The planar area and shape of the partial reflective layer 504 may be the same as or different from the planar area and shape of the working electrode layer 506. 【0140】 Advantageously, the partial reflective layer 504 is at least partially embedded in the material of the working electrode layer 506, and the material of the working electrode layer 506 is at least partially formed in the area between the patterned portions of the partial reflective layer 504, allowing the working electrode layer 506 to make direct mechanical contact with the transparent window 520. Thus, one or more regions within the partial reflective layer 504 configured to transmit electromagnetic radiation coincide with the portion of the working electrode layer 506 to be imaged. Advantageously, when the partial reflective layer 504 is at least partially embedded in the material of the working electrode layer 506 so as to extend downward from the surface of the working electrode layer 506 in a direction substantially perpendicular to the flat surface of the working electrode layer 506 to be imaged, the distance between the surface of the partial reflective layer 504 and the surface of the working electrode layer 506 can be reduced. Furthermore, by forming the working electrode layer 506 in an area between the substantially reflective areas of the partial reflective layer 504, a relatively flat area is obtained with respect to the surface of the partial reflective layer 504, and therefore, a wide surface area that can be imaged by dynamic autofocus is obtained. 【0141】 In other examples, instead or in addition, the partial reflective layer 504 comprises one or more reference markers to form one or more regions configured to reflect electromagnetic radiation, and the one or more reference markers are at least partially embedded in the surface of the working electrode layer 506. 【0142】 Figure 6 shows a cross-sectional view of the electrochemical cell 600. In the example of Figure 6, the electrochemical cell 600 has components equivalent to those shown for the electrochemical cell 300 shown in Figure 2. For example, the electrochemical cell 600 includes a cell housing 602. In the orientation shown, this is the lower cell housing 602 (the electrochemical cell 600 can be oriented in any convenient direction during use). The lower cell housing 602 has an aperture 603 that allows light to reach inside the electrochemical cell 600, in contrast to the opaque, apertureless housing 202 of the prior art electrochemical coin cell 200 described with reference to Figure 1B. As described with reference to the transparent window 320 in Figure 2, there is a transparent window 620 that allows light to reach inside the electrochemical cell 600 while sealing the aperture 603. Above the transparent window 620, the working electrode layer 606 is shown. Above the working electrode layer 606, Figure 6 shows a separator 608, a counter electrode 610, a spacer 612, and a spring 614, which correspond to the separator 308, counter electrode 310, spacer 312, and spring 314 described in relation to the electrochemical coin cell 300 in Figure 2. 【0143】 In contrast to the electrochemical cell 300 shown in Figure 2, the electrochemical cell 600 in Figure 6 shows a metal foil layer 604 that serves as a partial reflective layer 604. For example, the working electrode layer 606 is formed on the metal foil layer 604 by molding it onto the metal foil layer 604. The metal foil layer 604 extends to the cell housing 602 and is electrically connected to the cell housing 602 through a portion 618 of the metal foil layer 604. In other examples, the metal foil layer 604 does not directly electrically contact the cell housing 602, and the conductivity between the working electrode layer 606 and the cell housing 602 is provided by one or more separate conductive entities between the cell housing 602 and the working electrode layer 606. The planar area and shape of the partial reflective layer 604 may be the same as or different from the planar area and shape of the working electrode layer 606. 【0144】 Advantageously, the metal foil serves as a partial reflective layer 604, which is also a solid layer on which a working electrode layer 606 can be formed. At the same time, the metal foil layer 604 is conductive, while also providing one or more apertures for imaging the working electrode and smooth surfaces that can be used to obtain the correct reference reflection for autofocus. Thus, the partial reflective layer 604 includes one or more regions configured to reflect electromagnetic radiation and one or more regions configured to transmit electromagnetic radiation. 【0145】 Figure 7 shows a cross-sectional view of the electrochemical cell 700. In the example of Figure 7, the electrochemical cell 700 has components equivalent to those shown for the electrochemical cell 300 shown in Figure 2. For example, the electrochemical cell 700 includes a cell housing 702. In the orientation shown, this is the lower cell housing 702 (the electrochemical cell 700 can be oriented in any convenient direction during use). The lower cell housing 702 has an aperture 703 that allows light to reach inside the electrochemical cell 700, in contrast to the opaque, apertureless housing 202 of the prior art electrochemical coin cell 200 described with reference to Figure 1B. There is a transparent window 720 that allows light to reach inside the electrochemical cell 700 while sealing the aperture 703, as described with reference to the transparent window 320 in Figure 2. Above the transparent window 720, a working electrode layer 706 is shown. In the example of Figure 7, the working electrode layer 706 is a self-supporting electrode. In other examples, the working electrode layer 706 comprises one or more additional support layers on which the working electrode layer 706 is molded. A conductive mesh 718 is shown above the working electrode layer 706 and is electrically connected to the lower cell housing 702. Above the conductive mesh layer 718, in Figure 7, are shown a separator 708, a counter electrode 710, a spacer 712, and a spring 714, which correspond to the separator 308, counter electrode 310, spacer 312, and spring 314 described in relation to the electrochemical coin cell 300 in Figure 2. 【0146】 In contrast to the electrochemical cell 300 shown in Figure 2, the electrochemical cell 700 in Figure 7 shows a partial reflective layer 704. This partial reflective layer 704 is formed on the outer surface opposite to the transparent window and the working electrode layer 706, and is in close mechanical contact with the transparent window 720. The partial reflective layer 704 includes one or more regions configured to reflect electromagnetic radiation and one or more regions configured to transmit electromagnetic radiation. The planar area and shape of the partial reflective layer 704 may be the same as or different from the planar area and shape of the working electrode layer 706. 【0147】 Advantageously, the positioning of the partial reflective layer 704 on the transparent window 704 allows for excellent mechanical communication between the transparent window 720 and the working electrode layer 704, as the smooth surface of the transparent window 704 is pressed against the working electrode layer 704. As a result, changes at the interface between the partial reflective layer 704 and the material outside the electrochemical cell 700 (e.g., air, nitrogen, vacuum, etc.) represent changes in the working electrode layer 700. Furthermore, the partial reflective layer 704 on the outside of the electrochemical cell 700 can be replaced as needed without disturbing the rest of the electrochemical cell 700. Therefore, for example, it becomes possible to change the pattern of the partial reflective layer 704 to image different parts of the working electrode layer 706. 【0148】 An advantage is that the position of the partial reflective layer 704 on the outer surface of the transparent window 704 means that the electrochemical cell 700 can be assembled before the partial reflective layer 704 is formed. Therefore, the decision regarding where to form the reflective region of the partial reflective layer 704 can be made by understanding the area of ​​the working electrode layer 706 that can be seen through the aperture 703 within the cell housing 702 and making a decision based on that. 【0149】 Furthermore, beneficially, the positioning of the partial reflective layer 704 on the outer surface of the transparent window 704 allows for the use of an oil objective lens as part of the imaging device 328 to perform imaging and improve imaging resolution. 【0150】 The partial reflective layer 704 contains a metal. Beneficially, the metal layer allows for high reflectivity and precise control of the reflective region. In other examples, the partial reflective layer 704, either instead or in addition, contains an electrochemically active material having high reflectivity characteristics. Beneficially, a reflective region for reference reflection can be provided using a material that would otherwise not be usable inside the electrochemical cell 700. 【0151】 The electrochemical cells 500, 600, and 700, described with reference to Figures 5 to 7, are shown with specific configurations, but the formation and arrangement of the electrochemical cells 500, 600, and 700 can be modified in any suitable manner to provide the functions described herein in a manner similar to that of the electrochemical cell 300 in Figure 2. 【0152】 Figure 9 shows a cross-sectional view of a photoreachable electrochemical cell 3000 having a cell housing 302, aperture 303, and transparent window 320, as previously described in Figure 2. 【0153】 As shown in Figure 9, the working electrode layer 3060 is shown above the transparent window 320. The working electrode layer 3060 is a conventional working electrode layer having high-density active material particles molded on the foil layer 3040. 【0154】 A working electrode layer 3060, comprising active material particles and a foil layer 3040, forms a working electrode. The foil layer 3040 is an aluminum layer and acts as a foil current collector. In other examples, the foil layer 3040 may also contain a different conductive material, such as copper. The working electrode layer 3060 contains active material particles. In one example, the active material is lithium cobalt oxide (LCO). In another example, the active material is nickel-manganese-cobalt oxide (NMC). In yet another example, the working electrode layer 3060 may contain any suitable electrochemical cell material. In some examples, the working electrode layer 3060 may also contain additional materials, such as conductive additives and / or binder materials. 【0155】 The working electrode layer 3060 has a circular surface with a diameter of 10 mm and is formed on a circular aluminum foil layer 30400 with a thickness of 20 microns. In other examples, the working electrode is formed from working electrode layers 3060 and foil layers of different shapes and / or dimensions. 【0156】 The working electrode layer 3060 containing active material particles is positioned between the transparent window 320 and the foil layer 3040 of the working electrode so that the active material particles are visible through the transparent window 320. The working electrode layer 3060 containing the active material particles is pressed against the inner surface of the transparent window 320 so that the working electrode layer 3060 and the transparent window 320 are in mechanical communication. In other examples, there is one or more additional layers between the working electrode layer 3060 and the transparent window 320 so as to maintain the functions described herein. 【0157】 Both the working electrode layer 3060 and the foil layer 3040 are shown to have multiple channels 3220 that penetrate both the working electrode layer 3060 and the foil layer 3040. The channels 3220 allow the electrolyte within the electrochemical cell 3000 to reach the working electrode layer 3060. This is in contrast to conventional electrodes in which the foil layer, when pressed against the transparent window 320, lacks channels, preventing the electrolyte from reaching the working electrode layer containing the active material particles. 【0158】 While the channel 3220 shown in Figure 9 is shown to penetrate the entire height of the working electrode layer 3060 and the working electrode foil layer 3040, in other examples not shown, one or more of the channels 3220 partially penetrate the entire height of the working electrode layer 3060 so as to preserve the functions described herein. 【0159】 The interface between the transparent window 320 and the channel 3220 defines a sharp, flat surface with different refractive indices and can be used as a reference reflection interface for stabilizing the imaging focus, as described herein. For example, the difference between the refractive index of the glass in the transparent window 320 and the refractive index of the electrolyte in the channel 3220 provides an interface position that reflects the reference beam, as described herein. Furthermore, since the working electrode layer 3060 is mechanically coupled to the transparent window, changes in the position of the reflection interface between the transparent window 320 and the channel 3220 allow tracking of corresponding changes on the surface of the working electrode layer 3060 near the reflection interface, thereby providing input for adjusting the imaging focus of the working electrode layer 3060 in the event of any change in the position of the working electrode layer 3060 (e.g., due to expansion / contraction during operation of the electrochemical cell 3000). 【0160】 Similarly, during operation, changes in the refractive index of materials such as electrolytes within the channel alter the properties of the interface and therefore also alter the reflection of the reference beam directed toward the interface. Such changes describe the behavior in the working electrode layer 3060 and can also be used to convey the adjustment of the imaging focus of a portion of the working electrode layer 3060 during the electrochemical process. 【0161】 Multiple channels 3220 form circular cross-sectional holes that penetrate the working electrode. These holes have a diameter of 100 microns, a relative linear separation of 300 microns, and are arranged in a regular rectangular hole pattern. In other examples not shown, holes of arbitrary cross-sectional size and shape form multiple channels 3220 throughout the working electrode in any suitable regular or irregular formation or pattern. 【0162】 A conductive mesh 318 is shown above the foil layer 3040 and is electrically connected to the lower cell housing 302. The conductive mesh 318 is an aluminum mesh with open holes 1 mm in diameter and narrow ribbons of aluminum metal 140 microns wide. 【0163】 Figure 9 shows a conductive mesh 318, but in other examples not shown, the conductive mesh 318 is not included. For example, the working electrode layer 3060 may be in direct electrical contact with the cell housing 302. Alternatively and / or, the transparent window 320 may be at least partially conductive, thereby allowing conductivity between the working electrode layer 3060 and the cell housing 302. 【0164】 In other examples not shown, additional and / or alternative materials are used to provide electrical connections to the cell housing 302. 【0165】 Above the mesh 318, Figure 9 shows a separator 308, a counter electrode 310, a spacer 312, and a spring 314, which correspond to the separator 208, counter electrode 210, spacer 212, and spring 214 described in relation to the prior art conventional electrochemical coin cell 200 shown in Figures 1A and 1B. The separator 308 is a glass fiber separator, and the spacer 312 is a stainless steel spacer. Additional and / or alternative layers and / or components are implemented in other examples not shown. 【0166】 The stack of layers inside the electrochemical cell 3000 is moistened with an electrolyte. In one example, 200 μl of LP57 electrolyte is used. In yet another example, different amounts and / or types of electrolyte are used. The layers inside the electrochemical cell 3000 are sealed within the electrochemical cell 3000 by being enclosed by the upper cell housing 316. Light can reach the working electrode layer 3060 through a transparent window 320 created in the aperture 303 of the lower cell housing 302. 【0167】 While the electrochemical cell 3000 has been described in relation to specific layers formed in a particular order, in other examples, additional, fewer, and / or alternative layers and / or components may also be used to provide a light-reaching electrochemical cell in accordance with the claimed invention. For example, in another example, the working electrode is a self-supporting electrode layer that does not require the foil layer 3040. In yet another example, the working electrode includes the foil layer 3040 on the surface of the working electrode layer 3060, positioned between the transparent window 320 and the working electrode layer 3060. In such a configuration, the foil layer 3040 comprises one or more apertures, which expose corresponding portions of the working electrode layer 3060, thereby allowing light to reach the working electrode layer 3060 through the foil layer 3040 to image the working electrode layer 3060 in accordance with the method described herein. 【0168】 The cell housings 302 and 316 form a coin-type cell housing, such as a modified CR2032 coin-type cell housing. In other examples, the electrochemical cell 3000 has a different coin-type cell configuration. In yet another example, the electrochemical cell 3000 is a different type of cell, such as a pouch cell or a Swagelok (RTM) type cell, with similarly arranged internal components to obtain the advantages described herein. 【0169】 The electrical connections made to the upper cell housing 316 and the lower cell housing 302 facilitate the application of current-voltage states, such as charging and discharging states, which cause electrochemical processes to occur inside the electrochemical cell 3000. Such electrochemical processes can be imaged by imaging a portion of the working electrode layer 3060 that can be reached by light through the transparent window 320. 【0170】 Advantageously, the entities within the electrochemical cell 3000 are arranged, as described herein, to facilitate improved imaging, on the one hand, by allowing the electrolyte to reach the active material of the working electrode layer 3060 through the channel 3220. Furthermore, the electrochemical cell 3000 is relatively cost-effective, easy to assemble, can be integrated into root battery testing, and offers a significant improvement in circulating behavior compared to known cells. 【0171】 The working electrode layer 3060 is imaged using the imaging device 328. The imaging device 328 includes a light source 330 that supplies light for illumination / imaging in the direction indicated by the arrow 326. This light source is a 532 nm light-emitting diode (LED). In other examples, alternative and / or additional light sources, such as laser diodes, lamps, and / or LEDs with different peak wavelengths, are also used for illumination and / or imaging of the working electrode layer 3060. 【0172】 To image the working electrode layer 3060, the electrochemical cell 3000 is held in a suitable location, such as part of the sample stage. In one example, the imaging device 328 receives the electrochemical cell 3000 and provides a fixed position for making electrical connections to the electrodes of the electrochemical cell 3000 so that appropriate current-voltage conditions can be applied while imaging the working electrode layer 3060. 【0173】 Light source 330 guides light through an optical microscope to a visually exposed portion of the working electrode 306, positioned so that this portion of the working electrode 306 is imaged. The optical microscope comprises a lens system 332, a polarizing beam splitter 334 or beam splitter, a quarter-wave plate 336, and an objective lens 338. The light scattered by its portion of the working electrode layer 306 is then guided through the objective lens 338 and the quarter-wave plate 336, and through the beam splitter 334, through the lens system 340, to reach the camera 342, where an image of its portion of the working electrode layer 3060 is captured. 【0174】 While the optical microscope has a specific configuration for imaging the working electrode layer 3060, other examples may incorporate alternative and / or additional optical components to obtain focused images of a portion of the working electrode layer 3060 during the electrochemical process. 【0175】 The imaging device 328 communicates with the computing device 352 via a communication channel 346 located between the imaging device 328's interface and the computing device 352's interface 358. The computing device 352 comprises a processor 354 and memory 356. The computing device 352 communicates with the network 360 via a communication channel 350 located between the computing device 352 and the network 360. The imaging device 328 also communicates with the network 360 via the communication channel 348 and the imaging device 328's interface 344. 【0176】 The computing device 352 communicates with the autofocusing device 800. The autofocusing device 800 is described in more detail with reference to Figure 10. The autofocusing device 800 is used to guide and measure the reflection of the reference beam 324 from the reflection interface formed in the photoreaching electrochemical cell 3000. 【0177】 While the imaging device 328 and autofocus device 800 are shown to communicate with a computing device 352 and a network 360, in other embodiments not shown, the imaging device 328 and autofocus device 800 are implemented and controlled in any suitable manner according to the techniques described herein. In one example, the computing device 352 is integrated with the imaging device 328 and / or autofocus device 800. 【0178】 During imaging of a portion of the working electrode layer 3060, it is important to maintain focus on the surface of the portion of the working electrode layer 3060 that is being imaged. The computing device 352 communicates with the imaging device 328 and the autofocus device 800 and is configured to dynamically control the relative positions of the optical components of the imaging device 328 and / or the electrochemical cell 3000 of the imaging device 328. 【0179】 To maintain focus on a portion of the working electrode layer 3060 that is the target of imaging, the focal plane of the optical device is adjusted to be substantially perpendicular to the portion of the working electrode layer 3060. This may also be substantially perpendicular to the flat surface of the working electrode layer 3060 adjacent to the transparent window 320. In Cartesian coordinates where the flat surface of the working electrode layer 3060 lies in a plane substantially defined by the x and y axes, the focal plane of the optical device is adjusted along the z axis to obtain a focused image of a portion of the working electrode layer 3060. 【0180】 In the initial state, a portion of the working electrode layer 3060 can be focused by changing the relative position of the focal plane perpendicular to the z-axis so that a portion of the working electrode layer 3060 coincides with the focal plane of the optical device 328. However, during the real-time operation of the electrochemical cell 300, the application of current-voltage conditions may cause a portion of the working electrode layer 306 to change and no longer coincide with the focal plane. Such changes may result from expansion or contraction of the working electrode layer 3060 during operation, changes in the refractive index of the electrolyte inside the electrochemical cell 3000 during operation, and changes due to the oscillation of the sample stage supporting the electrochemical cell during operation. 【0181】 As mentioned above, the high density of the active material in conventional electrochemical cell electrodes means that the surface is rough and, as in the case of diluted electrochemical cell electrodes, is not suitable for use as a reference point to maintain focal stability. In diluted electrochemical cell electrodes, a reference light beam of a suitable spot size is positioned on a relatively smooth and inert surface between the active particles so that changes in the z position of the diluted electrode can be tracked. Advantageously, the channel 3220 of the photo-reaching electrochemical cell 3000 not only provides a path for the electrolyte to reach the active material particles of the working electrode layer 3060, but also provides a reference reflection interface between part of the transparent window 320 and part of the channel 3220. This reference reflection interface can be used to monitor changes in the working electrode layer 3060, and changes in the working electrode layer 3060 result in a change in the relative position difference between the part of the working electrode layer 3060 being imaged and the focal plane of the optical device 328 used to image the part of the working electrode layer 3060. 【0182】 Figure 3 shows the process flow S400 for imaging a portion of the working electrode layer 3060 of the photoreaching electrochemical cell 3000 during an electrochemical process. Process flow S400 is performed using the imaging device 328 described with reference to Figure 9, and / or in other embodiments referred to when describing the provision of similar or identical functionality for imaging a portion of the working electrode layer 3060 of the photoreaching electrochemical cell 3000. Process flow S400 is controlled using the computing device 352 described with reference to Figure 9. The computing device 352 is used to control the imaging process directly by controlling the imaging device 328, and / or indirectly through the computing network 360. 【0183】 This process begins in the first step S402 and proceeds to step S404, where a portion of the working electrode layer 3060 is imaged. This process may also be initiated by the user identifying the portion of the working electrode layer 3060 to be imaged and starting an experiment in which an electrochemical process is performed in the electrochemical cell 3000, while simultaneously imaged a portion of the working electrode layer 3060 and automatically maintaining focus on the portion of the working electrode layer 3060 being imaged. 【0184】 To image a portion of the working electrode layer 3060, the imaging device 328 is positioned so that its portion of the working electrode layer 3060 is illuminated by light, as indicated by arrow 326 in Figure 9. The imaging focus of the imaging device 328 is adjusted so that the focal plane of the imaging device 328 coincides with the portion of the working electrode layer 3060 to be imaged. The electrochemical process is initiated by applying the corresponding current-voltage state to electrodes 3060, 310 of the electrochemical cell 3000. 【0185】 One example of an electrochemical process is charging and discharging an electrochemical cell 3000 using a CC / 5 constant current (CC) rate (nominal 5-hour charge / discharge time) and a CC / 5 constant voltage (CV) rate for 1 hour, employing a CC / CV-CC / CV cycling protocol. Other examples will result in different electrochemical processes. 【0186】 Next, the process proceeds to step S406 to determine whether imaging is complete or not. The determination of whether imaging is complete or not is made at the discretion of the user, or, instead and / or in addition, by the control of the imaging device 328 based on computer implementation instructions executed by the computing device 352, for example, by the control of the imaging device 328 based on computer implementation instructions stored in the memory 356 of the computing device 352. 【0187】 If imaging is not yet complete, the process moves to step S408, where the reference reflection is monitored. The reference reflection is monitored by a combination of the computing device 352 and the imaging device 328. In one example, the computing device 352 is integrated with the imaging device 328. The computing device 352 is configured to implement a hardware or software feedback protocol, for example, a proportional-integral-derivative (PID) control system, and to have an input based on monitoring the reflection of the reference beam processed by the processor 354 to determine the focusing control of the imaging device 328. Imaging and focusing can be performed sequentially or in parallel. For example, the imaging device 328 may continue to capture images of a portion of the working electrode layer 3060, while the autofocus device 800 simultaneously monitors the reference reflection so that the computing device 352 adjusts the imaging and focusing in any suitable way. 【0188】 The reference reflection is monitored by directing focusing radiation toward the reference reflection interface, which includes a portion of the transparent window 320 and a portion of the channel 3220. Advantageously, the reflection interface provides a means for obtaining a sharp and consistent reflection, and this reflection is inseparably linked to the working electrode layer 3060 such that changes in the reflection at the reflection interface indicate changes in the working electrode layer 3060. This means that, for example, if the working electrode layer 3060 changes during operation, such as when a portion of the object being imaged moves and moves out of the focal plane of the imaging device 328, the change in the reflection at the reflection interface is used as input to compensate for this change by adjusting the focal plane of the imaging device 328 in a z-direction substantially perpendicular to the flat surface of the portion of the working electrode layer 3060 that is being imaged, thereby maintaining a stable focus. 【0189】 To monitor the reference reflection, the optical device 800, as described with reference to Figures 10A and 10B, is used in combination with the computing device 352 and / or the imaging device 328. 【0190】 Figure 10A shows an optical device 800A controlled by a computing device 352 that enables automatic focusing of the imaging device 328, illustrating the principle of using a reference beam reflected at the reflection interface to determine changes in reflection and compensate for those changes accordingly. 【0191】 A reference beam 802 from a light source is shown, which is guided to focus at the reflection interface by passing through the focusing lens 816, through the mirror 818, and then through the objective lens 820. The light source is a parallelized low-power laser beam with a wavelength of 785 nm. In other examples, any suitable light source of wavelength and power can be used to supply the reference beam. 【0192】 As indicated by arrow 324 in Figure 9, the reference beam is guided toward the interface between the transparent window 320 and the channel 3220 and passes through the working electrode layer 3060. Advantageously, the channel 3220 can accommodate an electrolyte, thereby supplying the electrolyte to the active material particles in the working electrode layer 3060 while simultaneously providing a reference point for determining any changes that may alter the imaging focus of the working electrode layer 3060. 【0193】 In the example shown in Figure 10A, a transparent window 320 is shown such that the reflective interface between the transparent window 320 and the channel 3220 is at a first position 810. The reference beam 802 is focused at the interface between the transparent window 320 and a portion of the channel 3220 at the first position 810. The reference beam 802 is focused to create a focus spot at the reflective interface, with a Gaussian full width at half maximum of 5 to 15 microns. In other examples, different spot sizes are used to monitor changes at the reflective interface. 【0194】 The first reflected beam 804 from the reflective interface between the transparent window 320 and the channel 3220 at the first position 810 is guided to reach the camera 824 through the objective lens 820 and the cylindrical lens 822. Here, the first reflected beam 804 appears (provides) as a reflected line at the first position 804'. This is shown in the projection 800B of the xy plane of the reference beam image captured by the camera 824 in Figure 10B. 【0195】 When the transparent window 320 moves in the z direction 812 and the reflection interface between the transparent window 320 and the channel 3220 reaches the second position 810', there is a change corresponding to the reflection of the reference beam 802, and the second reflected beam 806 from the reflection interface formed by the transparent window 320 and the channel 3220 at the second position 810' appears as a reflection line at the second position 806'. This is as shown in projection 800B of the reference beam image captured by the camera 824 in Figure 10B. 【0196】 The z-direction 812 corresponds to a direction substantially perpendicular to the flat surface of the working electrode layer 3060. Such changes in the position of the working electrode layer 3060 occur, for example, due to the expansion or contraction of the electrode under operating conditions. 【0197】 As the reflective interface between the transparent window 320 and the channel moves from the second position 810' to the third position 810'', there is a change corresponding to the reflection of the reference beam 802, and the third reflected beam 808 from the reflective interface formed by the transparent window 320 and the channel 322 at the third position 810'' appears as a reflection line at the third position 808'. This is as shown in projection 800B of the reference beam image captured by the camera 824 in Figure 10B. 【0198】 As shown in Figure 10A, the lateral positions of the reflected beams 804, 806, and 808 change in the lateral direction 814 in the xy-plane. These changes are perpendicular to the z-direction movement of the interface between the transparent window 320 and the channel 3220, and are a function of the position of the reflective interface between the transparent electrode 320 and the channel 3220. Therefore, by monitoring the reflection of the reference beam, changes in reflection at the reflective interface can be determined and the corresponding changes in the working electrode layer 3060 can be taken into account. 【0199】 The configurations of the autofocus optics 800A and 800B, described with reference to Figures 10A and 10B, monitor reflections so that these reflections appear as lines in the camera 824. In other examples, additional and / or alternative detections are used on the reflection being monitored to determine changes in the position of the interface between the transparent window 320 and the channel 3220, based on the position and intensity changes detected from the monitoring of the reflections. 【0200】 With respect to Figures 10A and 10B, a specific configuration of optical components for monitoring the reflection of a reference beam has been described; however, in other examples, additional and / or alternative optical components may be used to provide the functions described herein. 【0201】 Next, the process proceeds to step S410 to determine whether the reference reflection has changed. If the reference reflection has not changed, the process proceeds to step S404, in which the imaging device 328 re-images a portion of the working electrode layer 3060. If it is determined in step S406 that imaging has finished, the process ends in step S414. 【0202】 If it is determined in step S410 that the reference reflection has changed, the process moves to step S412, where the change during the electrochemical process is compensated for by adjusting the imaging focus of a portion of the working electrode. Since the change in the reflection of the reference beam at the reflection interface between the transparent window 320 and the channel 3220 fluctuates as a function of the corresponding change in the working electrode layer 3060, the focal plane of the imaging device 328 is adjusted based on the change in reflection at the reflection interface to compensate for the difference between the position of the focal plane and the portion of the working electrode layer 3060 that is being imaged. 【0203】 The imaging and monitoring steps of process flow S400 are repeated for the desired operating period of the electrochemical cell 3000 under investigation. While specific steps are shown in process flow S400, it will be understood by those skilled in the art that additional and / or alternative steps may be performed in other (not illustrated) embodiments, while providing the functionality described herein. In other embodiments, the steps of process flow S400 may be performed simultaneously or sequentially in any manner to provide the functionality to adjust the imaging of the working electrode in response to the determination of changes in the reference beam reflected at the reflective reference interface described herein. 【0204】 An advantage is that the electrochemical cell 3000, as described with reference to Figure 9, is configured to allow real-time monitoring of a portion of the working electrode in an improved manner. The frequency of imaging and adjustment of the imaging focus can be changed to determine the desired data. 【0205】 To prepare the working electrode layer 3060 and foil layer 3040 having active material particles and channels 3220 of a density that enables improved and stable imaging while simultaneously advancing the operation inside the photoreaching electrochemical cell 3000, processing steps as described with reference to Figures 11-13 are initiated. An example of a cross-section of the working electrode is described, showing a certain number of regular channels penetrating the working electrode. In other examples, the working electrode includes any number of channels formed in any suitable pattern and / or any suitable frequency, density, and regularity / irregularity. Typically, the working electrode has a circular flat surface for mounting in a coin-type cell device. However, in other examples, the working electrode including channels is formed in any suitable shape and size. 【0206】 Figures 11A and 11B show a series of cross-sectional images as part of a process for forming a perforated working electrode, such as the working electrode layer 3060 having a foil layer 3040 and a channel 3220 as described herein. 【0207】 The foil layer 504 is provided with a working electrode layer 506 formed on this foil layer, as shown in Figure 11A. The foil layer 504 and the working electrode layer 506 are mechanically perforated using a stamp 502 with multiple needles 503 to form multiple channels 508 that penetrate both the foil layer 504 and the working electrode layer 506, as shown in Figure 11B. Alternatively and / or in addition, the foil layer 504 and the working electrode layer 506 are perforated using laser perforation or laser excision to introduce the channels 508. In other examples, any suitable technique for perforating the foil layer 504 and / or the working electrode layer 506 is used to provide the perforated working electrode. While the mechanical perforation using the needle 503 of the stamp 502 is shown to proceed first through the foil layer 504 and then through the working electrode layer 506 containing the active material particles, in other examples, in order to preserve a flatter surface of the working electrode layer 506, the needle 503 of the stamp 502 is advanced to proceed first through the working electrode layer 506 and then through the foil layer 504. 【0208】 Figures 12A and 12B show a series of cross-sectional images as part of the process of forming a working electrode, such as the working electrode layer 3060 having the foil layer 3040 and channel 3220 described herein. 【0209】 As shown in Figure 12A, a fill or woven wire mesh layer is provided having one or more holes that penetrate the thickness, such as a mesh foil layer 604 having multiple channels 608 that penetrate the mesh foil layer 604. Then, as shown in Figure 12B, a working electrode layer 606 is formed on the mesh foil layer 604 to form a working electrode layer 606 having multiple channels 608. 【0210】 Figures 13A–13C show a series of cross-sectional images as part of the process of forming a working electrode, such as the working electrode layer 3060 having a foil layer 3040 and channels 3220 as described herein. As shown in Figure 13A, a foil layer 704 is prepared with a stamp 702 equipped with multiple needles 703. The foil layer 704 is mechanically perforated using the stamp 702 to form a foil layer 704 having multiple channels 708, as shown in Figure 13B. Subsequently, as shown in Figure 13C, a working electrode is formed on the perforated foil layer 704 to form a working electrode layer 706 having multiple channels 708. Alternatively and / or in addition, perforation of the foil layer 704 is performed using laser drilling or laser cutting to introduce the channels 708. In other examples, any suitable technique for perforating the foil layer 704 is used to obtain a perforated working electrode, such as providing a mesh and forming a working electrode 606 thereon. 【0211】 Beneficial in this regard, the use of a working electrode with multiple channels means that multiple portions of the working electrode layer to be imaged can be selected so that they are at a certain distance from the electrolyte's destination (for example, always a predetermined distance from the holes through the working electrode). Various other aspects and embodiments of the present invention will also be apparent to those skilled in the art in consideration of this disclosure. 【0212】 When “and / or” is used herein, it shall be construed as a specific disclosure of each of the two designated features or components, including or excluding the other. For example, “A and / or B” shall be construed as a specific disclosure of (i) A, (ii) B, and (iii) A and B, as each of them is individually expressed herein. 【0213】 Unless otherwise intended by context, the descriptions and definitions of the features expressed above are not limited to any particular aspect or embodiment of the present invention, but apply equally to all aspects and embodiments described herein. 【0214】 Furthermore, it will be acknowledged to those skilled in the art that the present invention has been described with reference to various embodiments as an example. This is not limited to the disclosed embodiments, and alternative embodiments can be constructed without departing from the scope of the invention as defined in the appended claims. 【0215】 Item(CLAUSES) a. An electrochemical cell, A working electrode including a channel that penetrates at least partially, A transparent window configured to allow light to reach the working electrode, A reflective interface between a part of the transparent window and a part of the channel, An electrochemical cell comprising a reflective interface configured such that a change in the reflective interface indicates a corresponding change in the working electrode. b. An electrochemical cell as described in clause a, An electrochemical cell comprising a foil layer on the first surface of a working electrode, with a transparent window configured to allow light to reach a second surface of the working electrode located opposite the first surface. c. An electrochemical cell as described in clause a, An electrochemical cell comprising a foil layer on a first surface of a working electrode, wherein a transparent window is configured to allow light to reach the first surface of the working electrode through one or more apertures in the foil layer. d. An electrochemical cell according to clause b or c, wherein the foil layer is a current collector and / or mesh layer. e. An electrochemical cell as described in any of the preceding clauses, wherein the channel penetrates the working electrode and the foil layer. f. An electrochemical cell as described in clause a, wherein the working electrode is a self-supporting working electrode. g. An electrochemical cell in which the channel contains an electrolyte, as described in any of the preceding clauses. h. An electrochemical cell as described in any of the preceding clauses, wherein the working electrode is mechanically connected to a transparent window. i. An electrochemical cell according to any of the preceding clauses, wherein the working electrode contains an active material, preferably the working electrode is loaded with at least 80% of the active material. j. An electrochemical cell as described in any of the preceding clauses, wherein the electrochemical cell is a coin-type cell and / or is mounted on a printed circuit board. k. A method for imaging a working electrode during at least a portion of an electrochemical process, The steps include monitoring reflection at the interface between a transparent window and a channel that at least partially penetrates the working electrode, The steps include: imaging a portion of the working electrode using an imaging device during at least a portion of the electrochemical process; A step of determining the change in reflection at the interface, A step of adjusting the imaging focus of the imaging device in response to the detection of a change, Methods that include... l. A method according to clause k, wherein the channel contains an electrolyte. A method according to clause k or l, wherein the step of monitoring reflection includes the step of guiding a reference beam toward the interface and detecting the position and / or intensity of the reflected reference beam. n. A method according to any one of clauses k to m, wherein the step of imaging a portion of the working electrode includes the step of imaging a first surface of the working electrode located opposite to the second surface of the working electrode, and the working electrode includes a foil layer on the second surface. o. A method according to any one of clauses k to n, wherein the step of adjusting the imaging focus includes a step of compensating for a change in the position of a portion of the working electrode in a direction substantially perpendicular to the focal plane by dynamically changing the focal plane of the imaging device. A method for preparing an imaging system to image a working electrode during at least part of an electrochemical process, in accordance with the method of clause k~o. q. A method according to clause p, further comprising the step of forming a channel that at least partially penetrates the working electrode. A method for forming channels in the method described in clause q, wherein a working electrode is formed on a foil mesh containing one or more channels. A method according to clause q, wherein a channel is formed by perforating a foil layer and forming a working electrode on the perforated foil layer. A method according to clause q, wherein a working electrode is formed on a foil layer, and then a channel is formed by perforating the working electrode. A method described in clause s or t, wherein the perforation includes the use of at least one of mechanical perforation, laser drilling, and laser excision. w. A system for imaging a working electrode during at least part of an electrochemical process, comprising an imaging system having a light source, the system being configured to perform the method described in any one of clauses k~o. x. A system described in clause w, wherein the system comprises an electrochemical cell described in any one of clauses a to j. y. A system according to either clause w or row x, wherein the system comprises an electrical connection for receiving battery electrodes. z. A system according to any one of clauses w to y, wherein the light source comprises at least one of a laser, a light-emitting diode, and a lamp, and / or the imaging device comprises an optical microscope.

Claims

[Claim 1] It is an electrochemical cell, Working electrode and, A transparent window configured to allow light to reach the working electrode, A partial reflective layer comprising one or more regions configured to reflect electromagnetic radiation and one or more regions configured to transmit electromagnetic radiation, Equipped with, The aforementioned partial reflective layer is configured to be in mechanical communication with the working electrode, and changes therein indicate corresponding changes in the working electrode. An electrochemical cell in which the working electrode is in substantially continuous contact with either the transparent window or the partial reflective layer. [Claim 2] An electrochemical cell according to claim 1, wherein the partial reflective layer is positioned at least partially between the transparent window and the working electrode. [Claim 3] An electrochemical cell according to claim 1, wherein the transparent window is positioned at least partially between the partial reflective layer and the working electrode. [Claim 4] An electrochemical cell according to claim 1 or 2, wherein the partial reflective layer is at least partially embedded in the working electrode. [Claim 5] An electrochemical cell according to any one of the preceding claims, wherein the partial reflective layer includes one or more apertures corresponding to one or more regions configured to transmit electromagnetic radiation, thereby allowing light to pass through the partial reflective layer to reach the working electrode. [Claim 6] An electrochemical cell according to any one of the preceding claims, comprising one or more layers positioned between the partially reflective layer and the transparent window. [Claim 7] An electrochemical cell according to any one of the preceding claims, wherein the transparent window includes a passivation layer. [Claim 8] An electrochemical cell according to claim 7, wherein the passivation layer is in substantially continuous contact with the partial reflective layer and / or the working electrode. [Claim 9] An electrochemical cell according to any one of the preceding claims, wherein the surface roughness of the reflective layer is less than 100 nm between peaks and valleys. [Claim 10] An electrochemical cell according to any one of the preceding claims, wherein the surface roughness of the reflective layer is less than 10 nm between peaks and valleys. [Claim 11] An electrochemical cell according to any one of the preceding claims, wherein the working electrode is a self-supporting working electrode or includes a support made of porous and conductive material. [Claim 12] An electrochemical cell according to any one of the preceding claims, wherein the electrochemical cell is a coin-type cell and / or is mounted on a printed circuit board. [Claim 13] A method for imaging a working electrode through a transparent window during at least part of an electrochemical process, The steps include monitoring reflection in a partial reflective layer that is mechanically in communication with the working electrode, The steps include: imaging a portion of the working electrode using an imaging device during at least a portion of the electrochemical process; The steps include determining the change in the reflection in the partial reflection layer, In response to the determination of the aforementioned change, the steps include adjusting the imaging focus of the imaging device, Includes, A method wherein the step of monitoring the reflection includes the step of directing a reference beam toward one of one or more regions of the partial reflective layer configured to reflect electromagnetic radiation, and the step of imaging the portion of the working electrode includes imaging through one or more regions of the partial reflective layer configured to transmit electromagnetic radiation, wherein the working electrode is in substantially continuous contact with either the transparent window or the partial reflective layer. [Claim 14] A method according to claim 13, wherein the step of monitoring the reflection includes the step of detecting the position and / or intensity of the reflected reference beam. [Claim 15] A method according to claim 13 or 14, wherein the step of adjusting the imaging focus includes a step of dynamically changing the focal plane of the imaging device to compensate for a change in the position of a portion of the working electrode in a direction substantially perpendicular to the focal plane. [Claim 16] A method for preparing an imaging system for imaging a working electrode during at least a portion of an electrochemical process, according to the methods described in claims 13 to 15. [Claim 17] A method according to claim 16, comprising the steps of forming the partial reflective layer on the transparent window, and then bringing the transparent window, together with the partial reflective layer, into substantially continuous contact with the working electrode. [Claim 18] A system for imaging a working electrode during at least part of an electrochemical process, A system comprising an imaging device equipped with a light source, wherein the system is configured to perform the method described in any one of claims 13 to 15. [Claim 19] A system according to claim 18, wherein the system comprises an electrochemical cell according to any one of claims 1 to 12. [Claim 20] A system according to any one of claims 18 and 19, wherein the system comprises an electrical connection for receiving an electrochemical cell. [Claim 21] A system according to any one of claims 18 to 20, wherein the light source includes at least one of a laser, a light-emitting diode, and a lamp, and / or the imaging device includes an optical microscope.

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