Electrolysis Cell Systems and Associated Electrolysis Systems and Methods

This application claims the benefit under 35 U.S.C. § 119 (e) of U.S. Provisional Patent Application Ser. No. 63/651,252, filed May 23, 2024, the disclosure of which is hereby incorporated herein in its entirety by this reference.

This invention was made with government support under Contract No. DE-AC07-05-ID14517 awarded by the United States Department of Energy. The government has certain rights in the invention.

Electrolysis cell systems are disclosed. More specifically, electrolysis cell systems and associated electrolysis systems and methods are disclosed.

Many desirable chemical elements are difficult to collect naturally. Electrolysis systems are used to separate the desirable chemical elements from base materials, which are more common chemical compounds that include the elements. For example, hydrogen (H) may be collected by separating the hydrogen from the base material water (HO). Electrolysis systems separate the base material into different compounds or elements by passing a current through the base material. The current through the base material is induced by a direct current (DC) voltage or potential applied across the electrolysis system.

Embodiments of the disclosure include an electrolysis cell system. The system includes one or more electrochemical cells configured to contain a base material, the base material defining a safe operating voltage of the one or more electrochemical cells. The system further includes a power source configured to supply a voltage to the one or more electrochemical cells. The system also includes a pulse width modulation (PWM) controller between the power source and the one or more electrochemical cells, the PWM controller configured to control the voltage supplied from the power source to the one or more electrochemical cells by pulsing the voltage between the safe operating voltage and a second voltage higher than the safe operating voltage.

Other embodiments of the disclosure include a method of operating an electrolysis cell system. The method includes applying a voltage across an electrochemical cell. The method further includes inducing a current through a base material in the electrochemical cell. The method also includes pulsing the voltage between a safe voltage and a relatively higher voltage than the safe voltage through a pulse width modulation (PWM) controller. The method further includes separating at least one element from the base material through electrolysis.

Another embodiment of the disclosure includes an electrolysis system. The system includes at least two electrochemical cells configured to contain a base material. The system further includes a power source configured to supply a voltage to the at least two electrochemical cells. The system also includes at least one pulse width modulation (PWM) controller between the power source and the at least two electrochemical cells, the at least one PWM controller configured to control the voltage supplied from the power source to the at least two electrochemical cells by pulsing the voltage between a safe voltage and a second voltage higher than the safe voltage.

The following description provides specific details, such as material compositions, shapes, and sizes, in order to provide a thorough description of embodiments of the disclosure. However, a person of ordinary skill in the art would understand that the embodiments of the disclosure may be practiced without employing these specific details. Indeed, the embodiments of the disclosure may be practiced in conjunction with conventional techniques employed in the industry.

Drawings presented herein are for illustrative purposes only, and are not meant to be actual views of any particular material, component, structure, device, or system. Variations from the shapes depicted in the drawings as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein are not to be construed as being limited to the particular shapes or regions as illustrated, but include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as box-shaped may have rough and/or nonlinear features, and a region illustrated or described as round may include some rough and/or linear features. Moreover, sharp angles that are illustrated may be rounded, and vice versa. Thus, the regions illustrated in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shape of a region and do not limit the scope of the present claims. The drawings are not necessarily to scale. Additionally, elements common between figures may retain the same numerical designation.

As used herein, the term “substantially” in reference to a given parameter means and includes to a degree that one skilled in the art would understand that the given parameter, property, or condition is met with a small degree of variance, such as within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially met, the parameter, property, or condition may be at least 90.0 percent met, at least 95.0 percent met, at least 99.0 percent met, at least 99.9 percent met, or even 100.0 percent met.

As used herein, “about” in reference to a numerical value for a particular parameter is inclusive of the numerical value and a degree of variance from the numerical value that one of ordinary skill in the art would understand is within acceptable tolerances for the particular parameter. For example, “about” in reference to a numerical value may include additional numerical values within a range of from 90.0 percent to 110.0 percent of the numerical value, such as within a range of from 95.0 percent to 105.0 percent of the numerical value, within a range of from 97.5 percent to 102.5 percent of the numerical value, within a range of from 99.0 percent to 101.0 percent of the numerical value, within a range of from 99.5 percent to 100.5 percent of the numerical value, or within a range of from 99.9 percent to 100.1 percent of the numerical value.

As used herein, relational terms, such as “below,” “lower,” “bottom,” “above,” “upper,” “top,” and the like, may be used for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the drawings. Unless otherwise specified, the spatially relative terms are intended to encompass different orientations of the materials in addition to the orientation depicted in the figures. For example, if materials in the figures are inverted, elements described as “below” or “under” or “on bottom of” other elements or features would then be oriented “above” or “on top of” the other elements or features. Thus, the term “below” can encompass both an orientation of above and below, depending on the context in which the term is used, which will be evident to one of ordinary skill in the art. The materials may be otherwise oriented (e.g., rotated 90 degrees, inverted, flipped) and the spatially relative descriptors used herein interpreted accordingly.

As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

As used herein, the term “and/or” means and includes any and all combinations of one or more of the associated listed items.

As used herein, the terms “vertical,” “longitudinal,” “horizontal,” and “lateral” are in reference to a major plane of a structure and are not necessarily defined by earth's gravitational field. A “horizontal” or “lateral” direction is a direction that is substantially parallel to the major plane of the structure, while a “vertical” or “longitudinal” direction is a direction that is substantially perpendicular to the major plane of the structure. The major plane of the structure is defined by a surface of the structure having a relatively large area compared to other surfaces of the structure.

Electrolysis systems may be used to separate elements (e.g., chemical elements) from a material (e.g., a base material) by applying an electrical current through the material. For example, base materials including oxygen, such as water (HO) and carbon dioxide (CO), may be separated through electrolysis to produce hydrogen (H) or a mixture of carbon monoxide (CO), and oxygen (O) when an electrical current is passed through the associated base material.

As current increases through an electrolysis system the quantity of the produced elements or compounds may also increase. Increasing the current through the electrolysis system may also increase the operating temperature of the electrolysis system and lead to additional material concentrations and/or reactions within the electrolysis system. When the temperature of the electrolysis system increases beyond a safe operating temperature, degradation of the electrolysis system may increase significantly, which causes the operating life of the electrolysis system to decrease significantly. Therefore, the currents through conventional electrolysis systems are induced at relatively low voltages and/or currents configured to maintain the associated electrolysis systems at a safe operating temperature. It has also been found that in electrolysis systems where the base material includes oxygen, operating at higher voltages and/or currents (e.g., above the relatively low voltages and/or currents) may also induce larger oxygen concentration gradients. The larger oxygen concentration gradients induced by the higher voltages and/or currents may cause structural damage (e.g., cell cracking, cell fracturing, etc.) which in many cases are not repairable.

Embodiments of the disclosure describe operating systems and methods that are configured to operate an electrolysis system at higher voltages and/or currents, increasing the production of one or more products of the electrolysis systems while mitigating the negative effects of operating at the higher voltages and/or currents. A production rate of the electrolysis product may be increased, without degrading electrochemical cells of the electrolysis systems, by periodically pulsing the electrochemical cells to higher voltages and/or currents for relatively short time periods. The higher voltages and/or currents may be greater than a so-called “safe operating voltage,” which is defined as the voltage where the electrochemical cell containing the base material is operated safely at a constant voltage for a long period of time with minimal degradation or damage of the electrochemical cell. Embodiments of the disclosure may facilitate increases of production of the electrolysis product over conventional electrolysis systems by more than 20% with little to no effect on the operating life of the associated electrolysis systems.

illustrates a schematic view of an electrolysis cell system. The electrolysis cell systemincludes one or more electrochemical cellsreceiving power from a power source, such as a battery, a power cell, line power, a power supply, an inverter, etc. In some embodiments the power sourceis a direct current (DC) power source. For example, the electrochemical cellmay be a solid oxide electrolyzer cell (SOEC) configured to achieve electrolysis of a base material, such as water or carbon dioxide, using a solid oxide or ceramic electrolyte. Other electrochemical cells may also be used. The amount of power provided to the electrochemical cellis controlled by a controller. In some embodiments, the controlleris configured to convert the power provided to the electrochemical cellto DC power, such as in embodiments where the power sourceprovides alternating current (AC) power.

A material collection devicemay be configured to collect elements or compounds (e.g., the one or more electrolysis products) generated through electrolysis of the base material, such as HO or CO, in the electrochemical cell. For example, the material collection devicemay collect one or more of H, CO, or Oseparated through electrolysis in an electrochemical cell. produced from other base materials or material compositions by electrolysis in an electrochemical cell. The material collection devicemay be a tank or reservoir configured to collect elements or compounds in a gas, vapor, liquid, or solid form. In some embodiments, the material collection deviceincludes additional components such as pumps or compressors configured to pressurize the elements or compounds as the elements or compounds are received from the electrochemical cell.

The controllermay be configured to control the power supplied to the electrochemical cellthrough pulse width modulation (PWM) (e.g., pulse-duration modulation (PDM) or pulse-length modulation (PLM)). PWM is a control strategy that changes a perceived power at a load, such as the electrochemical cell, by switching a power supplied to the load on and off during specified intervals, such that the ratio between the time the power supplied by the power sourceis on and the time the power supplied by the power sourceis off defines the perceived power or average power at the load. For example, if the power supplied by the power sourceis always on, the perceived power is 100% of the power being provided by the power source. If the power supplied by the power sourceis on 50% of the time, the perceived power is 50% of the power being provided by the power source.

PWM may also be used to provide power to the load while modulating the power supplied by the power sourcebetween two different voltages and/or currents. For example, the controllermay be configured to switch between two different voltages and/or currents multiple times in a short period of time as illustrated in. This modulation may facilitate operating the load at a higher power in short bursts and allowing the load to rest in short bursts to substantially prevent damage or rapid degradation to the electrochemical cellsthat may occur when operating at the higher power for longer periods of time. For example, in electrochemical cellsconfigured to produce hydrogen, operating the electrochemical cellat higher voltages and/or currents may result in excessive stressing of the electrochemical cell, leading to rapid degradation of the electrochemical cell. Operating electrochemical cellsconfigured to produce hydrogen at higher voltages and/or currents may also lead to the formation of oxygen concentration gradients within the electrochemical cellthat cause structural damage to the electrochemical cellthat is not reparable.

Because higher currents provided through the electrochemical cellsoperating at higher voltages and/or currents increase the production of the materials from the base materials through electrolysis, it is desirable to operate the electrochemical cellsat higher voltages and/or currents. It is surprising and unexpected that the electrochemical cellsmay be operated at higher voltages and/or currents, which are conventionally considered to be unsafe voltages and/or currents, when short rest periods operating at lower voltages and/or currents, which are considered safe voltages and/or currents, are included between the periods operating at the higher voltages and/or currents. This may result in higher production of the one or more electrolysis products from the associated electrochemical cellwith minimal effect on the operable life-span of the associated electrochemical cell.

illustrates a PWM control signal. The PWM control signalillustrates variations of a voltageover time. The voltageprovided to an electrochemical cell() correlates to the current passing through the electrochemical cell() and causing the electrolysis therein. In some embodiments, the voltageacross the electrochemical cellis controlled and in other embodiments, the current passing through the electrochemical cellis controlled. As noted above, the voltagecorrelates to the current, such that higher voltages result in higher currents and similarly higher currents result in higher voltages. As illustrated in the plot in, the voltageis pulsed, such that the plot defines a pulse regionwhere power is supplied from the power sourceto the electrochemical cellby a high voltageand a gap regionbetween pulse regionswhere the power from the power sourceto the electrochemical cellis supplied by a safe voltage. The safe voltageas used herein is a voltage where the associated electrochemical cellmay be operated safely at a constant voltage for long periods of time with minimal degradation or damage. The safe voltagemay vary based on the base material within the associated electrochemical cell. For example, an electrochemical cellcontaining water may have a different safe voltagethan an electrochemical cellcontaining carbon dioxide.

Each pulse regionmay have a substantially constant voltagebetween a startand a stop. The high voltagein each pulse regionmay be an over-potential in a range from about 0.1 Volts (V) to about 1 V, such as in a range from about 0.4 V to about 0.8 V. For example, an electrochemical cellconfigured to produce hydrogen through electrolysis may be configured to operate safely at about 1.3 V, therefore, the safe voltagemay be about 1.3 V, the high voltagemay be in a range from about 1.4 V to about 2.3 V, such as in a range from about 1.7 V to about 2.1 V.

The pulse regionhas a pulse periodand the gap regionhas a gap period. The combined pulse periodand gap perioddefine a cycle. The percentage of the cycledefined by the pulse periodmay be in a range from about 1% to about 80%, such as in a range from about 1% to about 50%, or a range from about 20% to about 50%. Resting the associated electrochemical cell() at the safe voltageduring the gap periodfor as little as 20% of the cyclemay be sufficient to prevent overstressing the electrochemical cell() and to substantially prevent damage from oxygen concentration gradients and other reactions that occur at the high voltage.

Each cyclemay extend from the time that the high voltageis supplied, through the time that the safe voltageis supplied until the high voltageis supplied again. The cyclesmay range from about 0.01 Hz (e.g., 100 second cycles or 0.01 cycles per second) to about 1 kHz (e.g., 0.001 second cycles or 1000 cycles per second), such as in a range from about 0.1 Hz (e.g., 10 second cycles or 0.01 cycles per second) to about 10 Hz (e.g., 0.1 second cycles or 10 cycles per second).

At the safe voltage, the associated electrochemical cellcontinues producing the associated material(s) in a state of electrolysis, such that the electrochemical cellis producing the associated material(s) throughout each cycle, with the change in production being the quantity of the material(s) produced during the pulse periodand the gap period.

illustrates an electrolysis systemincluding multiple electrolysis cell systems, such as electrolysis cell systems,,,. The electrolysis cell systems,,,may be similar to the electrolysis cell systemdescribed above, with respect toand includes similar components in substantially the same arrangement as described in. In some embodiments, each of the electrolysis cell systems,,,include a PWM controller similar to the PWM controllerillustrated inconfigured to control power supplied from a power supplyto the electrolysis cell systems,,,. The electrolysis cell systems,,,may each be operatively connected to a material collection deviceconfigured to collect the elements or compounds generated through electrolysis in the individual electrolysis cell systems,,,

In some embodiments, the material collection deviceis coupled to each of the electrolysis cell systems,,,individually through separate ports and/or tubing or pipes. In other embodiments, the material collection deviceis coupled to the electrolysis cell systems,,,through a manifold configured to consolidate the individual connections to the electrolysis cell systems,,,into a single or reduced number of connections at the material collection device. Similar to the material collection devicedescribed above, the material collection devicemay be a reservoir or tank configured to collect the elements or compounds in a gas, vapor, liquid, or solid form. The material collection devicemay also include a pump or compressor configured to pressurize the elements or compounds before the elements or compounds are collected in the material collection device.

As discussed above, a system controlleris configured to cycle the power supplied by the power supplyto the electrolysis cell systems,,,between a safe voltage and a high voltage greater than the safe voltage with a PWM style control, as illustrated and described in respect to. In some embodiments, the system controlleris a common controller connected between the power supplyand all of the electrolysis cell systems,,,. In other embodiments, the electrolysis systemmay include multiple system controllerscoupled between the power supplyand one or more of the electrolysis cell systems,,,, such as between the power supplyand one of the electrolysis cell systems,,,or between the power supplyand two of the electrolysis cell systems,,,

The system controllermay be configured to control the power supplied to the electrolysis cell systems,,,individually. This may facilitate offsetting the PWM control signals() of the electrolysis cell systems,,,. For example, the system controllermay control the power supplied to a first electrolysis cell systemand to a second electrolysis cell system, such that the pulse period() of the first electrolysis cell systemis aligned with the gap period() of the second electrolysis cell system. Offsetting the PWM control signals() of the individual electrolysis cell systems,,,may result in a substantially constant production rate for the electrolysis systemby alternating the rest periods (e.g., gap periods) between the individual electrolysis cell systems,,,and having at least one of the electrolysis cell systems,,,operating at the high voltageat all times.

For example,illustrates a plot of system control signalsfor the electrolysis system. The plot includes a signal for the electrolysis cell system, a signal for the electrolysis cell system, a signal for the electrolysis cell system, and a signal for the electrolysis cell systemeach separated vertically along the Y-axis and plotted against a common time scale in the X-axis to illustrate the offset of the signals. Similar to the PWM control signalillustrated in, each of the signals in the plot of the system control signalsrepresents a voltage,,,being provided to the associated electrolysis cell system,,,

In the embodiments illustrated in, the voltageassociated with the electrolysis cell systembegins in a high voltage regionand the voltageassociated with the electrolysis cell systembegins in a safe voltage region. The voltageof the electrolysis cell systemtransitions to the safe voltage regionas the voltagetransitions to the high voltage region. The voltageof the electrolysis cell systemalso begins in the safe voltage region. The voltageof the electrolysis cell systemtransitions to the high voltage regionas the voltageof the electrolysis cell systemtransitions back to the safe voltage regionand the voltageof the electrolysis cell systemremains in the safe voltage region. The voltageof the electrolysis cell systembegins by transitioning from the high voltage regionto the safe voltage region. The voltagetransitions back to the high voltage regionas the voltageof the electrolysis cell systemtransitions back to the safe voltage region. The voltageof the electrolysis cell systemthen transitions back to the safe voltage regionas the voltageof the electrolysis cell systemtransitions back to the high voltage region

In the embodiment illustrated in, the electrolysis systemhas at least one electrolysis cell system,,,operating in the high voltage region,,,at all times. Each of the electrolysis cell systems,,,are operating in the high voltage region,,,about 25% of the time. In other embodiments, the electrolysis cell systems,,,may operate in the high voltage region,,,a greater percentage, such as 40% of the time, 50% of the time, or even 80% of the time. When the electrolysis cell systems,,,are operating in the high voltage region,,,a greater percentage of the time, the high voltage regions,,,of one or more of the electrolysis cell systems,,,may overlap, such that two or more of the electrolysis cell systems,,,are operating in the high voltage region,,,at any given time.

In the embodiments illustrated in, the electrolysis systemincludes four electrolysis cell systems,,,. In some embodiments, the electrolysis system may include fewer electrolysis cell systems, such as two electrolysis cell systemsor three electrolysis cell systems. In other embodiments, the electrolysis systemmay include a greater number of electrolysis cell systems, such as ten electrolysis cell systemsor twenty electrolysis cell systems. A greater number of electrolysis cell systemsmay facilitate maintaining at least one of the electrolysis cell systemsat the high voltage region,,,in embodiments where the period is less than ¼th of the cycle length. In other cases a greater number of electrolysis cell systemsmay increase the overlap in the high voltage regions,,,of the associated electrolysis cell systems.

illustrates a simplified electrical schematicof a control system in accordance with embodiments of the disclosure. The control system may be configured to be integrated into one or more of the electrolysis cell systems (e.g., the electrolysis cell systemor the electrolysis system) described herein. The control system includes a function generator, a current controller, and a power supply. The function generatoris configured to generate a signal configured to trigger a PWM signal, such as the PWM control signalor one or more of the system control signals. The function generatoris coupled to the current controller, which controls current supplied by the power supplybased on the signal provided by the function generator.

The power supplymay be a direct current power supply. In some embodiments, the power supplyis configured to receive alternating current power, such as line power, and convert the alternating current to direct current power. The current supplied by the power supplyand controlled by the current controlleris transmitted to an electrolysis cell(e.g., electrochemical cells, or electrolysis cell systems,,,,, etc.). The current controllerincludes a relayconfigured to pulse the current supplied by the power supplywhen the signal provided by the function generatoris above a threshold level. For example, the signal provided by the function generatormay be an oscillating signal, such as a sinusoidal oscillating signal. The function generatormay be configured to supply the oscillating signal at a relatively low current, such as in a range from about 10 mA to about 200 mA with a peak to peak voltage in a range from about 1 Vpp to about 10 Vpp. The relaymay be configured to close when the signal is above a threshold value and open when the signal falls below the threshold value. In other embodiments, the relaymay be a normally closed relay. When the signal increases above the threshold value, the relayopens, interrupting the current from the power supply. When the signal decreases below the threshold value the relaycloses, restoring the current from the power supply.

The current flowing through the relaymay form a substantially square wave of pulses that substantially coincide with the frequency of the signal provided by the function generator. As discussed above, pulsing the current may facilitate operating the electrolysis cellat a higher voltage than are conventionally considered to be safe, by providing short rest periods operating at conventionally safe voltages between the periods operating at the higher voltages. This may result in higher production from the associated electrochemical cellwith minimal effect on the operable life-span of the associated electrochemical cell.

The control system may also include a regulatorand a current measurement circuitthat may be used to monitor and control the current passing through and the voltage across the electrolysis cell. For example, the regulatormay be used to monitor and limit the pulsed voltage applied across the electrolysis cell. The regulatormay be a potentiostat. As discussed above, the pulsed voltage across the electrolysis cellmay be greater than a conventionally safe voltage. While the pulsed voltage is higher, the regulatormay be configured to limit the pulsed voltage to a pulsed safe voltage (e.g., a voltage where the pulsed voltage will not excessively stress the electrolysis celland cause degradation of the electrolysis cellduring the short pulsed time period). For example, the power supplymay be configured to supply a voltage that is greater than a pulsed safe voltage and the regulatormay be configured to limit the voltage of the pulses supplied from the current controllerto below the pulsed safe voltage.

The pulsed safe voltage may vary depending on factors, such as the frequency of the pulses and the period or length of the pulses. The current measurement circuitmay provide a user with additional information regarding the current leaving the current controller. The current measurement circuitmay facilitate making adjustments to the regulatorbased on the current pulses measured by the current measurement circuit. In some embodiments, a separate controller (i.e., in addition to the current controller) may monitor the current measurement circuitand adjust the regulatorbased on the measurements received by the current measurement circuit. In other embodiments, the current measurement circuitmay provide the measurements to a display where an operator may make control adjustments to the regulatorand/or the function generatorbased on the displayed measurements.

Embodiments of the disclosure may facilitate operating an electrolysis cell at voltages and/or currents above what is conventionally understood to be safe voltages and/or currents of operation without an increase in degradation or damage to the associated electrolysis cells. Operating the electrolysis cells at higher voltages and/or currents may result in higher rates of production of one or more electrolysis products. Increasing production from an electrolysis cell may reduce the number of electrolysis cells used to produce a given amount of an element or compound. Reducing the number of electrolysis cells may, in turn, reduce the space used by an operation for a similar production quantity or facilitate increasing the production of an electrolysis operation without increasing the space used by the operation.

The embodiments of the disclosure described above and illustrated in the accompanying drawing figures do not limit the scope of the invention, since these embodiments are merely examples of embodiments of the invention, which is defined by the appended claims and their legal equivalents. Any equivalent embodiments are intended to be within the scope of this disclosure. Indeed, various modifications of the present disclosure, in addition to those shown and described herein, such as alternative useful combinations of the elements described, may become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the appended claims and their legal equivalents.