Electrochemical cell controller

Abstract

A controller operable to perform electrochemical cell management operations. In a non-limiting example, the electrochemical cell management operations include, based at least in part on a determination that a first electrochemical cell of an electrochemical cell system has not reached a target voltage, controlling a current to pass through the electrochemical cell system including the first electrochemical cell. The electrochemical cell management operations further include, based at least in part on a determination that the first electrochemical cell of the electrochemical cell system has reached the target voltage, controlling the current to substantially bypass the first electrochemical cell and pass through portions of the electrochemical cell system that have not been bypassed.

Description

ELECTROCHEMICAL CELL CONTROLLERCROSS-REFERENCE TO RELATED APPLICATIONThis application claims priority to U.S. Provisional Patent Application No.63 / 511,346, filed on June 30, 2023, the contents of which are hereby incorporated by reference in their entirety.BACKGROUND

[0001] Disclosed is an electronic controller for electrochemical cells. More specifically, disclosed is an electronic control system operable to control various aspects of operating one or more electrochemical cells.

[0002] Electrochemical cells are used in a variety of systems for conducting electrochemical processes. Electrochemical cells come in multiple forms, including, for example, rechargeable batteries. Another form of electrochemical cell is an electroswing absorption (ESA) system operable to separate a target species from a fluid mixture.

[0003] Electronic management systems have been developed to control various aspects of how electrochemical cells operate. For example, battery management systems (BMS) have been developed to control various aspects of charging and discharging rechargeable batteries. A BMS can be formed from many functional blocks including cutoff field effect transistors (FETs), a fuel gauge monitor, a cell voltage monitor, cell voltage balance, real time clock (RTC), temperature monitors, and a state machine. A conventional BMS can be provided as an integrated circuit (IC). The grouping of the functional blocks in a BMS IC varies widely from a simple analog front end that offers balancing and monitoring and requires a microcontroller (MCU), to a standalone, highly integrated BMS that runs autonomously.

[0004] Although electronic management systems have been developed for electrochemical cells and electronic storage devices, there remains a need for electronic control systems that provide improved control over various operations of electrochemical cells, including, but not limited to, avoiding undesirable overvoltage or undervoltage conditions, and improved control of charge operations, discharge operations, and functional tasks performed by the electrochemical cell(s).SUMMARY

[0005] Disclosed is a controller operable to perform electrochemical cell management operations. In a non-limiting example, the electrochemical cell management operations include, based at least in part on a determination that a first electrochemical cell of an electrochemical cell stack has not reached a target voltage, controlling a current to pass through the electrochemical cell stack including the first electrochemical cell. The electrochemical cell management operations further include, based at least in pail on a determination that the first electrochemical cell of the electrochemical cell stack has reached the target voltage, controlling the current to substantially bypass the first electrochemical cell and pass through portions of the electrochemical cell stack that are not bypassed.

[0006] In some aspects the target voltage is a target charge voltage and the current is a charge current.

[0007] In some aspects the target voltage is a target discharge voltage and the current is a discharge current.

[0008] In some aspects performing the electrochemical cell management operations include controlling a charge stage of the electrochemical cell stack such that the target voltage includes a target charge voltage and the current includes a charge current; and controlling a discharge stage of the electrochemical cell stack such that the target voltage comprises a target discharge voltage and the current comprises a discharge current.

[0009] Also disclosed is a system including the controller.

[0010] Also disclosed is a gas separation system including the controller in fluidic communication with a gas inlet and a gas outlet.

[0011] Embodiments are also directed to computer- implemented methods and computer program products having substantially the same features and technical benefits and effects as the controller described above.

[0012] Additional features and advantages are realized through techniques described herein. Other embodiments and aspects are described in detail herein. For a better understanding, refer to the description and to the drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The subject matter which is regarded as embodiments is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the embodiments are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

[0014] FIG. 1A depicts a simplified block diagram illustrating an embodiment of a system;

[0015] FIG. IB depicts a block diagram illustrating an aspect of the system;

[0016] FIG. 2 is a flow diagram illustrating an embodiment of a control methodology;

[0017] FIG. 3 includes graphs of voltage (V) versus time and current versus time illustrating an embodiment of how voltage and current are controlled in charge and discharge operations;

[0018] FIG. 4A depicts a simplified block diagram illustrating an embodiment of charge control operations applied to a single electrochemical cell;

[0019] FIG. 4B depicts a simplified block diagram illustrating an embodiment of charge control operations applied to a stack of electrochemical cells;

[0020] FIG. 5 depicts tables illustrating improved control when using stepped charge and discharge voltages for each individual electrochemical cell;

[0021] FIG. 6 depicts a simplified block diagram illustrating an embodiment of a controller operable to perform charge and discharge control operations;

[0022] FIG. 7 depicts a simplified block diagram illustrating an embodiment of a controller operable to control charge and discharge operations;

[0023] FIG. 8 depicts a simplified block diagram of a computing system operable to implement the controller;

[0024] FIG. 9 depicts a simplified block diagram illustrating an embodiment of an electrochemical cell operable to receive charge and discharge control operations;

[0025] FIG. 10 is a graph of voltage (Volts, V) versus time (hours, h) showing the cell voltage of each cell in Comparative Example 1 ;

[0026] FIG. 11 is a graph of voltage (V) versus time (h) showing the cell voltage of each cell in Example 1 ; and

[0027] FIG. 12 is an enlarged view of a portion of FIG. 12.DETAILED DESCRIPTION

[0028] For the sake of brevity, conventional techniques related to making and using aspects of the invention may or may not be described in detail herein. In particular, various aspects of electronic circuitry, computing systems, and specific computer programs to implement the various technical features described herein are well known. Accordingly, in the interest of brevity, many conventional implementation details are only mentioned briefly herein or are omitted entirely without providing the well-known system and / or process details.

[0029] Rechargeable energy storage devices (ESDs) (e.g., batteries, capacitors, and the like) often include a battery management system (BMS) designed to assist with the control of charge and discharge. In a battery, a plurality of electrochemical cells connected in a series configuration, referred to as a cell stack, is typically charged by forcing a current through the cell stack. It is a goal of known charging operations to pass a charging current through the cell stack until a desired charge voltage is across the cell stack, and then holding the cell stack at the desired charge voltage for a desired time duration. Similarly, on discharge, it is a goal of known discharging operation to pass a discharging current through the cell stack, and then hold the cell stack at the desired discharge voltage for a desired time duration. However, known BMS controls of charge and discharge operations assume that each individual ESD (i.e., cell) in the cell stack will increase in voltage evenly, which is not always the case. Even for ESDs that each have the same “listed” performance specification, differences in fabrication processes and electroactive materials result in variation in the actual capacity and actual performance of each ESD from the ESD’s listed performance specification. These differences can result in the individual ESDs in a cell stack, while ostensibly the same, not charging or discharging uniformly. When individual ESDs in a cell stack do not charge and / or discharge uniformly, individual ESDs in the cell stack can charge or discharge to a voltage that is beyond the target voltage, which can prevent other ESDs in the cell stack from charging or discharging to the target voltage. A cell stack having a cell, which has been charged to a voltage that is above and / or below the target voltage, can result in an overvoltage or undervoltage condition that can cause operational inefficiency, performance behavior that is detrimental to overall cell stack health, or the creation of a charge state that activates an undesired or potentially harmful reaction (e.g., an undesired redox chemical reaction).

[0030] Alternatively, in other electrochemical systems, such as electroswing adsorption (ESA) systems, voltage can be used to selectively activate desirable processes. ESA is a method of capturing a target species, e.g., a Lewis acid gas, from a fluid mixture. Similar’ to the abovedescribed ESDs, ESA systems can also include a stack of electrochemical cells, where each electrochemical cell is an ESA cell operable to, under voltage control, perform a desirable process such as capturing a target species, e.g., a Lewis acid gas, from a fluid mixture. While ESA is an effective process for removing a target species from a fluid, the efficiency and productivity of the process can be limited by improper application of voltage to the ESA cell. In particular, the applied voltage in an ESA can be specifically selected to selectively capture or release a selected target species, e.g., a Lewis acid gas. If an individual ESA cell in a cell stack is charged or discharged to a voltage different from the target voltage, an overvoltage or undervoltage condition would occur that could result in activation of a process different from that intended, a loss of selectivity, or undesirable oxidative or reductive processes. In other words, the overvoltage or undervoltage condition could render the ESA cell less effective or ineffective at capturing the target species from a fluid mixture.

[0031] Disclosed is a controller operable to control the charging and / or discharging operations applied to one or more electrochemical cells in a manner that provides improved selection and control of desired electrochemical processes, or prevents or avoids cell damage by providing improved control to avoid an overvoltage condition and / or an undervoltage condition. In aspects of the invention, an overvoltage condition occurs when an electrochemical cell has a voltage that exceeds, i.e., is more positive than, a target charge voltage. An overvoltage condition can occur during a charge operation of the one or more electrochemical cells. For example, if the target charge voltage is 1.0 V, an overvoltage condition can occur when an electrochemical cell has a voltage greater than 1.0 V, e.g., 1.30 V. In contrast, an undervoltage condition occurs when the cell has voltage that is less than, i.e., more negative, than the target discharge voltage (e.g. It is possible to have an undervoltage if desired discharge voltage is 0.3V and 0.2V is applied). For example, in a discharge operation, the target discharge voltage can be -1.0 V and an undervoltage condition can occur when the electrochemical cell has voltage less than -1.0V, e.g., -1.30 V. Discharge operations can also occur at a positive voltage that is smaller than the charge potential. Here too, the undervoltage is defined as a voltage smaller than the target discharge voltage. In aspects of theinvention where multiple electrochemical cells are being charged as a group, and where the electrochemical cells do not charge to the target charge voltage at the same rate, the controller can intentionally correct charging operations for an electrochemical cell that achieves, and optionally maintains, a target charge voltage, and this correction to the charging operations for the electrochemical cell that has achieved the target charge voltage is performed without interfering with the charging operations applied to other electrochemical cells that have not yet reached the target charge voltage. Similarly, where multiple electrochemical cells are discharged, and where the electrochemical cells do not discharge to the target discharge voltage at the same rate, the controller can intentionally correct discharging operations for an electrochemical cell that achieves, and optionally maintains, a target discharge voltage, and this correction to the discharging operations for the electrochemical cell that has achieved the target discharge voltage is performed without interfering with the discharging operations applied to other electrochemical cells that have not yet reached the target discharge voltage.

[0032] In aspects of the invention, multiple target charge voltages can be used. The target charge voltage can comprise any suitable number of target charge voltages, e.g., a first target charge voltage and a second target charge voltage. In aspects of the invention the first target charge voltage is less than the second target charge voltage and one or more electrochemical cells are charged to multiple potentials sequentially, e.g., to the first target charge voltage and then to the second target charge voltage. Thus the cells may be charged to the first target charge voltage to provide a first state of charge, and then charged to the second target charge voltage, where the state of charge of the cells increases further. The target charge voltages are set and controlled by the controller described herein.

[0033] In aspects of the invention in which the electrochemical cells are electroswing adsorption cells, use of multiple target charge voltages can provide for selective capture of different target species, e.g., different target gases such as CO2, SO2, sequentially at each charge voltage from a mixture of multiple gases. Thus, a first species may be adsorbed at the first target charge voltage, and a second species different from the first species may be adsorbed at the second target charge voltage. Thus as the charge voltage is effectively sequentially stepped up in voltage, the electroswing adsorption cell may capture different species.

[0034] Similarly, multiple target discharge voltages can be used. The target discharge voltage can comprise any suitable number of target discharge voltages, e.g., a first target discharge voltage and a second target discharge voltage. In aspects of the invention the first target discharge voltage is more positive, or less negative, than the second target discharge voltage and one or more electrochemical cells are discharged to multiple potentials sequentially, e.g., to the first target discharge voltage and then to the second target discharge voltage. Thus the cells may be discharged to the first target discharge voltage to provide a first state of charge, and then discharged to the second target discharge voltage to provide a second state of charge. The target discharge voltages are set and controlled via the controllers described herein.

[0035] In aspect in which the electrochemical cells are electroswing adsorption cells, use of multiple target discharge voltages can provide for selective release different target species, e.g., different target gases, sequentially at each target discharge voltage as the discharge voltage is effectively sequentially stepped down.

[0036] Disclosed is a controller electrically coupled with a sensor network, a voltage / current source, and an electrochemical system having one or more electrochemical cells. In aspects of the invention, the electrochemical system comprises a plurality of the electrochemical cells connected in series to provide a cell stack. The electrochemical system may be a gas separation system configured to selectively capture or release a Lewis acid gas from a fluid mixture. The system may comprise multiple cell stacks, and the cells may be connected in any suitable combination of series and parallel connections. The controller can be implemented in any suitable fashion, including, for example, various combinations of logic circuits, software controls, and the like. In aspects of the invention the controller can be implemented to have centralized control elements, distributed control elements, virtualized control elements, or other suitable control element configurations. For example, some functionality of the controller can be performed by a corresponding control element within the sensor network (e.g., an loT device), the voltage / current source, the electrochemical system, a cloud computing system (e.g., the cloud computing system 50 (shown in FIG. 1A), and the like.

[0037] In operation, the controller and the voltage / current source send a charging or discharging current, e.g., a constant charging or discharging current, through the electrochemical system; and the controller and the sensor network monitor the voltage of selected individualelectrochemical cells in the cell stack, e.g., each cell in a stack of electrochemical cells, during the charge or discharge operation. When individual electrochemical cells in the cell stack reach the target charge voltage, even when other individual electrochemical cells in the cell stack have not reached the target charge voltage, the controller controls the charge current’ s path such that the charging current that would have gone through the electrochemical cells that have reached the target charge voltage is instead routed through an alternative path, e.g., a shunt element parallel to the electrochemical cells that have reached the target charge voltage, thereby bypassing the electrochemical cells that have reached the target charge voltage and preventing the bypassed electrochemical cells from experiencing an overvoltage condition. Preventing each electrochemical cell in the electrochemical system from experiencing an overvoltage condition prevents any cell in the electrochemical system from experiencing an overvoltage condition during normal charging operations, e.g., charging to a target charge voltage.

[0038] Similarly, when any of the individual electrochemical cells in the cell stack reach the target discharge voltage, even when other individual electrochemical cells in the cell stack have not reached the target discharge voltage, the controller controls the discharge current’s path such that the discharge current that would have gone through the electrochemical cells that have reached the target discharge voltage is instead routed through an alternative path, e.g., a shunt element parallel to the electrochemical cells that have reached the target discharge voltage, thereby bypassing the electrochemical cells that have reached the target discharge voltage and preventing the bypassed electrochemical cells from experiencing an undervoltage condition. Preventing each electrochemical cell in the cell stack from experiencing an undervoltage condition prevents any cell in the cell stack from experiencing an undervoltage condition during normal discharging operations, e.g., discharging to a target discharge voltage.

[0039] In aspects of the invention the disclosed controller enables independent control of the target charge voltage and the target discharge voltage at any selected individual cell, and in aspects of the invention enables independent control of the target charge voltage and the target discharge voltage for each individual electrochemical cell. In aspects of the invention the target charge voltage and target discharge voltage for each cell can be independently selected. Thus a first electrochemical cell can be charged to a first target charge voltage and discharged to a first target discharge voltage, and a second electrochemical cells can be charged to a second target chargevoltage and discharged to a second discharge voltage, wherein the first target charge voltage and the second target charge voltage may be independently selected and may be different, or the first target discharge voltage and the second target discharge voltage may be independently selected and may be different.

[0040] Additionally, multiple target charge voltages and multiple discharge voltages may be applied to a selected electrochemical cell. Thus the charge or discharge voltage can be applied in a stepped pattern where the charge voltage can be stepped up to a first target charge voltage, held at the first target charge voltage for a first period of time, and then stepped up to a second target charge voltage for a second period of time. The first target charge voltage and the first period of time can be selected to capture a first species; and the second charge voltage and the second period of time can be selected to capture a second species . In aspects of the invention, the charge voltage may be stepped from a first target charge voltage to a second target charge voltage so that the electrochemical cell first captures a first target gas, and then captures a second target gas. Alternatively, the first target charge voltage may be applied to the first electrochemical cell to capture the first target species, and the second target charge voltage may be applied to the second electrochemical cell to capture the second target species.

[0041] Similarly, the target discharge voltage can be applied in a stepped pattern. Thus the first target discharge voltage can be held for a third period of time to release the first species and then the discharge voltage stepped to a more negative second target discharge voltage for a fourth period of time to release the second species. Alternatively, the first target discharge voltage may be applied to the first electrochemical cell to release the first target species, and the second target charge voltage may be applied to the second electrochemical cell to release the second target species. For instance, in an ESA cell that has captured combination of carbon dioxide and sulfur dioxide, a target discharge voltage of -0.2 V can be applied to release the carbon dioxide, and then a target discharge voltage of -0.5 V applied to release the sulfur dioxide.

[0042] The disclosed system may find applicability in a battery by avoiding an overvoltage or undervoltage condition in a cell that would otherwise cause degradative oxidation or reduction of the cell components, such as oxidation of the electrolyte at the cathode, oxidation of the cathode active material, or undesirable reduction such as reductive plating of a metal. The disclosed system may also find applicability to prevent an overvoltage or undervoltage condition that wouldotherwise drive the oxidation of a catalyst support in a fuel-cell or in an air battery, e.g., oxidation of a carbonaceous catalyst support in air. The disclosed novel method of bypassing current is applicable for both charge operations, when current is moving in a first direction, and for discharge operations, when current is moving in a second direction opposite to the first direction.

[0043] Also provided is a controller operable to provide improved charge and discharge conditions for electrochemical cells, avoiding degradation that can occur from an overvoltage or undervoltage condition during charge or discharge operations. In some electrochemical processes, additional technical benefits include providing an efficient and reliable mechanism for maintaining operation of the electrochemical cell within a target voltage range in order to provide the desired outcome (e.g., selection of a desired electrochemical reaction).

[0044] Turning now to a more detailed description of aspects of the invention, FIG. 1A depicts a simplified block diagram illustrating an embodiment of a system 100. The system 100 includes a controller 110, a network of current / voltage sensors 130, and at least one current / voltage source 140. The controller 110, cell stack 120, network of current / voltage sensors 130, and at least one current / voltage source 140 may be configured and arranged as shown. The controller 110 can be implemented as a controller system having centralized control elements, distributed control elements, virtualized control elements, or any other suitable control element configuration. For example, functionality of the controller 110 described herein can be performed by a corresponding control element within the sensor network 130 comprising the current / voltage sensors 130 (e.g., an loT device), the at least one voltage / current source 140, an electrochemical cell stack 120, a cloud computing system 50, and the like.

[0045] FIG. IB depicts a block diagram illustrating an embodiment of a system 100. As shown in FIG. IB, the electrochemical cell stack 120 comprises a plurality of any suitable number of electrochemical cells connected in series, e.g., a first electrochemical cell 121, a second electrochemical cell 122, a third electrochemical cell 123, and a fourth electrochemical cell 124. The controller 110 is electronically coupled to the electrochemical cell stack 120 through the network of current / voltage sensors 130 and at least one current / voltage source. As shown in FIG, IB, a current bypass path is provided for each cell, e.g., first current bypass path 151, a second current bypass path 152, a third current bypass path 153, and fourth current bypass path 154. As is also shown in FIG. IB, the network of current / voltage sensors may comprise a first current / voltagesensor 131, a second current / voltage sensor 132, a third current / voltage sensor 133, a fourth current / voltage sensor 134, a fifth current / voltage sensor 135, and a sixth current / voltage sensor 136, and a first current / voltage source 141, and a second current / voltage source 142. The electrochemical cell stack 120 may be incorporated as part of the system 100, or the electrochemical cell stack 120 may be separate from, but coupled to or in electrical communication with, the system 100. The electrochemical cell stack 120 comprises one or more electrochemical cells electrically coupled to one another, and may comprise other structures (e.g., housing, electrodes, wiring, or circuitry) for routing the charge or discharge current from the current / voltage source, through the one or more electrochemical cells of the electrochemical cell stack 120. In aspects of the invention, the network of current / voltage sensors 130 is operable to provide the current, voltage, and other measurements associated with each individual electrochemical cell of the electrochemical cell stack 120.

[0046] The cloud computing system 50 may be in wired or wireless electronic communication with the system 100, and in particular with the controller 110. The cloud computing system 50 can supplement, support, or replace some or all of the functionality (in any combination) of the system 100, including specifically the disclosed charge or discharge management operations performed and / or controlled by the controller 110. Additionally, some or all of the functionality of the system 100, including specifically the disclosed charge or discharge management operations performed and / or controlled by the controller 110, can be implemented as a node of the cloud computing system 50. Additional details of cloud computing functionality that can be used are depicted by the computing system / environment 800 shown in FIG. 8 and described in greater detail subsequently herein.

[0047] FIG. 2 depicts a flow diagram illustrating a methodology 200 that can be performed by the system 100. More specifically, the methodology 200 can be implemented by the controller 110, and the controller 110 can be implemented using the circuitry shown in FIGS. 6 and 7 and / or the computing system 800 shown in FIG. 8. FIG. 3 depicts graph 302A of voltage (V) versus time, and graph 302B of current (I) over time (t), respectively. The graphs 302 A, 302B depict the rise and fall of charging current and voltage applied to each electrochemical cell of the electrochemical cell stack 120 during a charge operation (C / V (high)) and a subsequent discharge operation (C / V (low)). As depicted in FIG. 3, a charging / discharging operation can charge and discharges theelectrochemical cells in the electrochemical cell stack 120 by providing a current (+ / -I, see graph 302B) into each electrochemical cell in the electrochemical cell stack 120 until a desired voltage (+ / -V, see graph 302A) is reached or the process times out. As shown in FIG. 3, in a first time period tl the cell stack is charged at a constant current until the target charge voltage is reached, and then in a second period time t2 the cell stack is charged at constant voltage (CV (high)) to a current limit or for a selected amount of time. On discharge, in a third period of time t3 the cell stack is discharged to a target discharge voltage at a constant current (CC (out)), and then in a fourth period of time t4 at constant voltage (C / V (low) to a current limit or until the process times out.

[0048] The methodology 200 will now be described with reference to the flow diagram shown in FIG. 2, the corresponding components of the system 100 shown in FIGS. 1A or IB, and the corresponding portions of the graphs 302 A, 302B shown in FIG. 3. The methodology 200 applies to charge operations alone, discharge operations alone, and / or charge operations combined with subsequent discharge operations. The methodology 200 begins at block 202 and moves to block 204 where the controller 110 controls the at least one current / voltage source to provide current through the electrochemical cell stack 120. At block 206, the methodology 200 monitors readings from the network of current / voltage sensors 130. The network of current / voltage sensors 130 is operable to provide individual readings on the current, voltage, and other measurements from each individual electrochemical cell, e.g., cells 121 to 124 of the electrochemical cell stack 120.

[0049] At decision block 208, the controller 110 uses the results generated at block 206 to identify an electrochemical cell in the electrochemical cell stack 120 that has reached the target voltage, e.g., a target charge voltage CV (high), or target discharge voltage e.g., CV (low), shown in FIG. 3.

[0050] An electrochemical cell that has reached the target charge voltage or target discharge voltage can drift over time, or appear to drift due to effects such as internal resistance, for example. To accommodate drift, decision block 208 can also identify an electrochemical cell that has reached the target voltage and is below the target voltage and within a predetermined range (e.g., V-range 310 and / or V-range 320) of the target voltage. Thus on charge, decision block 208 can identify the electrochemical cell(s) in the electrochemical cell stack 120 that have reached the target change voltage and are below the target charge voltage and within a predetermined range (e.g., V-range 310 and / or V-range 320) of the target charge voltage. Similarly, on discharge decision block 208 canidentify the electrochemical cell(s) in the electrochemical cell stack 120 that have reached the target discharge voltage and are above the target discharge voltage and within a predetermined range (e.g., V-range 310 and / or V-range 320) of the target discharge voltage. Also, the methodology 200 can continue to bypass any electrochemical cell that has reached the target voltage, as long as the actual voltage of the electrochemical cell is within the predetermined charge range, e.g., V-range 310 and / or V-range 320) of the target voltage. If the answer to the inquiry at decision block 208 is yes, the methodology 200 moves to block 210 where the controller 110 controls the electrochemical cell stack 120 to control the current (generated by the at least one current / voltage source) to bypass each electrochemical cell in the electrochemical cell stack 120 that has reached the target voltage and / or has reached the target voltage and is and is within the predetermined range of the target voltage (e.g., V-range 310, 320 shown in FIG. 3). Thus on charge, the controller 110 controls the current to bypass each electrochemical cell in the electrochemical cell stack 120 that has reached the target charge voltage or optionally has reached the target charge voltage and is below the target charge voltage and within the predetermined range of the target charge voltage (e.g., V-range 310, 320 shown in FIG. 3). Similarly, on discharge the controller 110 controls the current to bypass each electrochemical cell in the electrochemical cell stack 120 that has reached the target discharge voltage and optionally has reached the target discharge voltage and is above the target discharge voltage and within the predetermined range of the target discharge voltage. From block 210, the methodology 200 moves to decision block 212 to determine whether an interrupt instruction has been received at the system 100. If the answer to the inquiry at decision block 212 is yes, the methodology 200 moves to block 214 and ends. If the answer to the inquiry at decision block 212 is no, the methodology 200 returns to block 206 and receives updated readings from the network of current / voltage sensors 130.

[0051] Returning back to decision block 208, if the answer to the inquiry at decision block 208 is no, the methodology 200 skips block 210 and moves to decision block 212 to determine whether an interrupt instruction has been received at the system 100. If the answer to the inquiry at decision block 212 is yes, the methodology 200 moves to block 214 and ends. If the answer to the inquiry at decision block 212 is no, the methodology 200 returns to block 206 and receives updated readings from the network of current / voltage sensors 130.

[0052] The methodology 200 may be implemented such that the target voltage is target charge voltage, and the current is a charge current. Providing the target charge voltage may involve changing the charge current.

[0053] The methodology 200 may implemented such that the target voltage is a target discharge voltage, and the current is a discharge current. Providing the target discharge voltage may involve changing the discharge current.

[0054] The methodology 200 may be part of a set of electrochemical cell management operations that include performing one instance of the methodology 200 as a charge stage and performing another instance of the methodology 200 as a discharge stage. In the charge stage, the electrochemical cell management operations are performed such that the target voltage includes a target charge voltage and the current includes a charge current. In the discharge stage, the electrochemical cell management operations are performed such that the target voltage includes a target discharge voltage and the current includes a discharge current. The set of electrochemical cell management operations may be operable to switch from the charge stage to the discharge stage subsequent to detecting that all of the electrochemical cells have been charged.

[0055] FIG. 4A depicts a simplified block diagram illustrating an aspect of charge control operations (e.g., the methodology 200 shown in FIG. 2) applied to a single electrochemical cell 410A. The single electrochemical cell 410A can be a cell of the electrochemical cell stack 120. As shown, the single electrochemical cell 410A is modeled as an individual energy storage device (ESD) in parallel with a variable resistance (R). The charge current is represented as the system current (i-system) that can be controlled (e.g., in accordance with the methodology 200 shown in FIG. 2) to either pass substantially through the ESD (e.g., as i-ESD) or pass substantially through R (e.g., as i-bypass) where the path through R functions as a bypass leg. In embodiments of the invention, the controller 110 controls whether i-system passes through the ESD or the R by, in effect, controlling the value of R. Setting a high value for R (i.e., higher than the resistance of the ESD) ensures that i-system passes substantially through the ESD. Setting a low value for R (i.e., substantially lower than the resistance of the ESD) ensures that i-system passes substantially through R.

[0056] FIG. 4B depicts a simplified block diagram illustrating an aspect of charge control operations applied to a stack of electrochemical cells 410B, 410C, 410D. The stack ofelectrochemical cells 410B, 410C, 410D may be pail of the electrochemical cell stack 120, e.g., corresponding to cells 122, 123, and 124 in FIG. IB, respectively. Each of the electrochemical cells 410B, 410C, 410D is controlled in the manner depicted in FIG. 4A for the electrochemical cell 410A. As shown in FIG. 4B, the electrochemical cells 410B, 410D have reached the target voltage sooner than the electrochemical cell 410C. Accordingly, electrochemical cells 410B, 410D are bypassed while electrochemical cell 410C continues to receive the current applied to the stack. In the example depicted in FIG. 4B, whenever the system 100 determines that electrochemical cell 410C has reached the target voltage, all of the electrochemical cells 410B, 410C, 410D are bypassed. In aspects of the invention, the target voltage depicted in FIG. 4B is a target charge voltage. Discharge control operations can be performed substantially similarly as the charge operations shown in FIG. 4B, except that the target voltage is a target discharge voltage and the stack current flows in an opposite direction from that on charge as shown in FIG 5A.

[0057] FIG. 5 depicts tables 502, 504 illustrating how the system 100 can be used to provide stepped charge voltages and stepped discharge voltages for each individual electrochemical cell (e.g., electrochemical cells 410A, 410B, 410C, 410D shown in FIGS. 4A and 4B) of an electrochemical cell stack (e.g., electrochemical cell stack 120. As shown in FIG. 5, table 502 illustrates an example of a first stepped charge / discharge voltage sequence applied to electrochemical cell-A; and table 504 illustrates an example of a second stepped charge / discharge voltage sequence applied to electrochemical cell-B. Each of table 502, 504 illustrates a target voltage, a duration that each target voltage is maintained, and the electrochemical cell operation that is initiated by the target voltage being maintained for its corresponding duration. In aspects of the invention, electrochemical cell-A and electrochemical cell-B are arranged in a stack, and the system 100 is configured to apply the first stepped charge / discharge voltage sequence to electrochemical cell-A independently from applying the second stepped charge / discharge voltage sequence to electrochemical cell-B. The system 100 may be configured to apply the first stepped charge / discharge voltage sequence to electrochemical cell-A independently from and concurrently with applying the second stepped charge / discharge voltage sequence to electrochemical cell-B .

[0058] As shown in table 502, the first stepped charge / discharge voltage sequence begins by performing charge operations that raise the voltage across electrochemical cell-A to charge voltagel for a duration of Tl. For example, charge voltagel may be positive 0.30 V. Electrochemical cell-Amay be configured and arranged (e.g., configured and arranged as ESA-1 shown in FIG. 9) such that maintaining charge voltage 1 for duration T1 across electrochemical cell- A results in electrochemical cell-A capturing a first species, e.g., gas-A. Subsequently, the first stepped charge / discharge voltage sequence raises the voltage across electrochemical cell-A to charge voltage2 for a duration of T2. Charge voltage2 may be greater than charge voltagel, e.g., positive 0.60 V. Electrochemical cell-A may be configured and arranged (e.g., configured and arranged as ESA-1 shown in FIG. 9) such that maintaining charge voltage2 for duration T2 across electrochemical cell-A results in electrochemical cell-A capturing a second species, e.g., gas-B. Subsequently, the first stepped charge / discharge voltage sequence raises the voltage across electrochemical cell-A to charge voltage3 for a duration of T3. Charge voltage3 may be greater than charge voltage2, e.g., positive 1.0 V. Electrochemical cell-A is configured and arranged (e.g., configured and arranged as ESA-1 shown in FIG. 9) such that maintaining charge voltage3 for duration T3 across electrochemical cell-A results in electrochemical cell-A capturing a third species, e.g., gas-C.

[0059] Subsequently, the first stepped charge / discharge voltage sequence performs discharge operations by setting the voltage across electrochemical cell-A to discharge voltagel for a duration of Tl. For example, discharge voltagel may be negative 0.30 V. Electrochemical cell-A may be configured and arranged (e.g., configured and arranged as ESA-1 shown in FIG. 9) such that maintaining discharge voltagel for duration Tl across electrochemical cell-A results in electrochemical cell-A releasing the first species, e.g., gas-A. Subsequently, the first stepped charge / discharge voltage sequence sets the voltage across electrochemical cell-A to discharge voltage2 for a duration of T2. Discharge voltage2 is more negative than discharge voltagel, e.g., negative 0.60 V. Electrochemical cell-A is configured and arranged (e.g., configured and arranged as ESA-1 shown in FIG. 9) such that maintaining discharge voltage2 for duration T2 across electrochemical cell-A results in electrochemical cell-A releasing the second species, e.g., gas-B. Subsequently, the first stepped charge / discharge voltage sequence sets the voltage across electrochemical cell-A to discharge voltage3 for a duration of T3. Discharge voltage3 is more negative than discharge voltage2, and may be negative 1.0 V. Electrochemical cell-A is configured and arranged (e.g., configured and arranged as ESA-1 shown in FIG. 9) such that maintainingdischarge voltage3 for duration T3 across electrochemical cell-A results in electrochemical cell-A releasing the third species, e.g., gas-C.

[0060] As shown in table 504, the second stepped charge / discharge voltage sequence begins by performing charge operations that raise the voltage across electrochemical cell-B to charge voltage 1 for a duration of T5. In aspects of the invention, charge voltage 1 is positive 0.50 V. Electrochemical cell-B may be configured and arranged (e.g., configured and arranged as ESA-1 shown in FIG. 9) such that maintaining charge voltagel for duration T5 across electrochemical cell- B results in electrochemical cell-B capturing the fourth species, e.g., gas-D. Subsequently, the second stepped charge / discharge voltage sequence raises the voltage across electrochemical cell-B to charge voltage2 for a duration of T6. Charge voltage2 is greater than charge voltage 1, and may be positive 1.0 V. Electrochemical cell-B is configured and arranged (e.g., configured and arranged as ESA-1 shown in FIG. 9) such that maintaining charge voltage2 for duration T6 across electrochemical cell-B results in electrochemical cell-B capturing the third species, e.g., gas-C.

[0061] Subsequently, the second stepped charge / discharge voltage sequence performs discharge operations by setting the voltage across electrochemical cell-B to discharge voltagel for a duration of T5. In aspects of the invention, discharge voltagel is, for example, negative 0.50 V. Electrochemical cell-B is configured and arranged (e.g., configured and arranged as ESA-1 shown in FIG. 9) such that maintaining discharge voltagel for duration T5 across electrochemical cell-B results in electrochemical cell-B releasing the fourth species, e.g., gas-D. Subsequently, the second stepped charge / discharge voltage sequence sets the voltage across electrochemical cell-B to discharge voltage2 for a duration of T6. Discharge voltage2 is more negative than discharge voltage 1, and may be for example negative 1.0 V. Electrochemical cell-B is configured and arranged (e.g., configured and arranged as ESA-1 shown in FIG. 9) such that maintaining discharge voltage2 for duration T6 across electrochemical cell-B results in electrochemical cell-B releasing the third species, e.g., gas-C.

[0062] FIG. 6 depicts a simplified block diagram illustrating an example of how the controller 110 can be implemented as a charge management controller 110A having a current controller circuit 610 operable to apply the disclosed charge or discharge management operations to a single electrochemical cell 420F using a C / V source 630. Multiple instances of the current controller 610 can be provided and made operable to control a corresponding cell of multipleinstances of the electrochemical cell 420F. The current controller 610 may comprise a current / voltage sensor 620, a bypass current leg 640, a shunted / bypass current sensor 642, a discharge controller 650, Switch- 1, Switch-2, and charge controller 660, configured and arranged as shown. The C / V sensor 620 can be implemented as an Op Amp subtractor (e.g., as shown by the “voltage sensor” shown in FIG. 7) that measures the voltage of the electrochemical cell 420F. The shunted / bypass current sensor 642 can also be implemented as an Op Amp subtractor (e.g., as shown by the “shunted / bypass current sensor” shown in FIG. 7) that measures current flowing through the bypass current leg 640. The discharge controller 650 can be implemented as an Op Amp (e.g., as shown by the “controller for switch 1” shown in FIG. 7) operable to activate Switch-1 when the discharge voltage is reached by the electrochemical cell 420F. The charge controller 660 can be implemented as an Op Amp (e.g., as shown by the “controller for switch 2” shown in FIG. 7) operable to activate Switch-2 when the charge voltage is reached by the electrochemical cell 420F.

[0063] In aspects of the invention the charge or discharge management operations performed by the controller 110 using the methodology 200 (depicted in FIG. 2) can be implemented by a programmable computer system, such as the computing system 900 shown in FIG. 8.

[0064] FIG. 8 illustrates an example of a computer system 800 that can be used to implement the computer-based components described herein. The computer system 800 includes an exemplary computing device (“computer”) 802 configured for performing various aspects of the content-based semantic monitoring operations described herein. In addition to computer 802, exemplary computer system 800 includes network 814, which connects computer 802 to additional systems (not depicted) and can include one or more wide area networks (WANs) and / or local area networks (LANs) such as the Internet, intranet(s), and / or wireless communication network(s). Computer 802 and additional system are in communication via network 814, e.g., to communicate data between them.

[0065] Exemplary computer 802 includes processor cores 804, main memory (“memory”) 810, and input / output component(s) 812, which are in communication via bus 803. Processor cores 804 includes cache memory (“cache”) 806 and controls 808, which include branch prediction structures and associated search, hit, detect and update logic, which will be described in more detail below. Cache 806 can include multiple cache levels (not depicted) that are on or off-chip fromprocessor 804. Memory 810 can include various data stored therein, e.g., instructions, software, routines, etc., which, e.g., can be transferred to / from cache 806 by controls 808 for execution by processor 804. Input / output component(s) 812 can include one or more components that facilitate local and / or remote input / output operations to / from computer 802, such as a display, keyboard, modem, network adapter, etc. (not depicted).

[0066] FIG. 9 depicts a simplified block diagram illustrating an example of how electrochemical cells of the electrochemical cell stack 120 can be implemented as a set of electroswing absorption (ESA) cells. While in FIG. 9 only two ESA cells are shown, the stack can include any suitable number of ESA cells, e.g., 1 to 1000, 2 to 500, or 3 to 100 cells. ESA-1 and ESA-2 each operate in substantially the same way, and so in the interest of brevity only ESA-1 is described in detail. As depicted in FIG. 9, ESA-1 is an electrochemical cell having a first current collector 910a, a counter electrode 920a, a separator 930a, a working electrode 940a, a flow field 950a, and a second current collector 960a, configured and arranged as shown. As shown in FIG. 9, the second current collector 960a may be between adjacent ESA cells and be a bipolar plate, e.g., a negative electrode current collector to the first ESA cell and a positive current collector to an adjacent ESA cell.

[0067] ESA cells ESA-1 and ESA-2 are operable to be controlled using charge control operations as disclosed herein. In general, ESA-1 and ESA-2 are each operable to capture one or more target species, for example, a Lewis acid gas (e.g., CO2), from a fluid mixture, such as air, by an electrochemical process that contacts the fluid mixture with an electroactive species.

[0068] The fluid mixture comprising the target species, e.g., a Lewis acid gas, can be directed into ESA-1 (and particularly the flow field) and a charge is applied across first current collector 910a and the second current collector 960a. The fluid mixture may be air and the target species may be CO2. Accordingly, the fluid that flows out of ESA-1 will have less of the target species, e.g., less CO2, than the fluid that flowed into ESA-1. The voltage maintained across first current collector 910a and second current collector 960a creates a voltage difference that pulls charge from the working electrode to the counter electrode. The Lewis acid gas (e.g., CO2) is released from ESA-1 by discharging ESA-1 using, for example, the discharge operations (C / V (low) and CC (out)) 302A, 302B shown in FIG. 3.

[0069] The first current collector 910a, the second current collector 960a, or the bipolar plate may each independently comprise any suitable material. Suitable examples can include carbon-based materials, which can include, but are not limited to, graphite, flaked graphite, expanded graphite, carbon fiber, carbon nanotubes, amorphous carbon, graphene, or a combination thereof. The carbon nanotubes may comprise single-wall carbon nanotubes or multi-wall carbon nanotubes. Carbon nanotubes are primarily carbon, although the nanotube fiber may further comprise other atoms, such as boron, nitrogen, or one or more of various metals. Mentioned is graphite. In aspects of the invention, the current collector can comprise a metal. The metal can comprise Fe, Zn, Ti, Cu, Al, Ni, Mg, Sn, Cr, Mn, Au, Mo, W, In, V, Nb, Ag, an alloy or intermetallic thereof, or a combination thereof. In aspects of the invention the alloy is a stainless steel, such as 304 or 316 stainless steel. Suitable metals may include aluminum, nickel, alloys thereof such as stainless steel, or a combination thereof.

[0070] The working electrode 940a of the electrochemical cell includes an electroactive species in a reduced state. As used herein, an “electroactive species” refers to an agent (e.g., a chemical entity) which undergoes oxidation or reduction upon exposure to an electrical potential in an electrochemical cell. The electroactive species is capable of bonding with or binding to a target gas when the electroactive species is in a first oxidation state and releasing the target species when the electroactive species is in a second oxidation state. The first oxidation state can be a reduced state and the second oxidation state can be an oxidized state. Stated another way, the electroactive species can be reduced to a corresponding reduced state, which binds to the target gas forming a complex or an adduct. Subsequent oxidation of the electroactive species can release the target gas. In aspects of the invention, the first oxidation state of the electroactive species can be provided by the first selection voltage, and the second oxidation state can be provided by the second selection voltage. As a non-limiting example, if the electroactive species is benzoquinone, the neutral benzoquinone would be considered the oxidized state, the semiquinone (e.g., a product of the addition of one electron to neutral benzoquinone) would be considered one reduced state, and the benzoquinone dianion (the product of the addition of one electron to neutral benzoquinone) would be considered a second reduced state.

[0071] The electroactive species can be selected such that in at least one reduced state, the electroactive species can have a strong affinity for the target gas. In aspects of the invention, in areduced state, the electroactive species can have a binding constant with the target gas of at least 101liters / mole, (M'1), or at least 102M’1, or at least 103M"1at room temperature (e.g., 23°C). Within this range, the electroactive species (in a reduced state) can have a binding constant with the target gas of 101to IO20M’1, 103to 1019M’1, 104to 1018M’1, 105to 1017M’1, 106to 1016M’1, or 107to 1015M’1. In aspects of the invention, the binding constant with the target gas is 105to IO20M’1, or IO10to IO13M'1. In aspects of the invention, the target gas can be carbon dioxide (CO2), and the electroactive species (in a reduced state) can have a binding constant with the CO2 of 101to 1015. In aspects of the invention, the target gas can be sulfur dioxide (SO2), and the electroactive species (in a reduced state) can have a binding constant with the SO2 of 105to IO20.

[0072] The electroactive species can have an oxidized state, wherein upon oxidation, the target gas can be released from the electroactive species. The binding constant of the reduced electroactive species can be greater than the binding constant of the corresponding oxidized electroactive species. Accordingly, in an advantageous feature, capture and release of the target gas can be achieved through redox cycling.

[0073] The electroactive species can be capable of binding the target gas on a timescale on the order of minutes, on the order of seconds, on the order of milliseconds, or on the order of microseconds or less.

[0074] In aspects of the invention, the electroactive species can have a reduced state in which the electroactive species is capable of bonding with the target gas, but for which there is at least one temperature (e.g., in a range of greater than or equal to 223 K, greater than or equal to 248 K, greater than or equal to 273 K, or greater than or equal to 298 K, and up to 323 K, up to 348 K, or up to 413 K, for example 298 K) at which it is thermodynamically unfavorable for the electroactive species to react with oxygen (O2). In aspects of the invention, the electroactive species can have a reduced state in which the electroactive species is capable of bonding with the target gas, but for which there is at least one temperature (e.g., 298 K) at which it is kinetically unfavorable for the electroactive species to react with oxygen (O2) because a rate, e.g., rate constant, for the reaction with oxygen is too slow for a reaction to occur on a timescale commensurate with capture of the target gas. Accordingly, the electroactive species of the composite effectively provides a suitable specificity towards capture of the target gas.

[0075] The electroactive species can comprise an electroactive polymer, an electroactive oligomer, an electroactive organic compound, or a combination thereof. The electroactive species can include at least one functional group capable of binding to a target gas, for example a carbonyl group.

[0076] Exemplary electroactive organic compounds can include, but are not limited to, a substituted or unsubstituted quinone or tetrone. In aspects of the invention, the electroactive species comprises a substituted or unsubstituted quinone (e.g., the quinone can include one or more functional groups or other moieties or linkages bound to the quinone). The choice of substituent (e.g., functional groups) on the substituted quinone can depend on a variety of factors, including but not limited to its effect on the reduction potential of the substituted quinone. One of ordinary skill, with the benefit of this disclosure, would understand how to determine which substituents or combinations of substituents on the substituted quinone are suitable for the first electroactive species based on, for example synthetic feasibility and resulting reduction potential. Exemplary functional groups can include, but are not limited to, halo (e.g., chloro, bromo, iodo), hydroxyl, carboxylate / carboxylic acid, sulfonate / sulfonic acid, alkylsulfonate / alkylsulfonic acid, phosphonate / phosphonic acid, alkylphosphonate / alkylphosphonic acid, acyl (e.g., acetyl or ethyl ester), amino, amido, quaternary ammonium (e.g., tetraalkylamino), branched or unbranched alkyl (e.g., Ci-18 alkyl), heteroalkyl, alkoxy, glycoxy, polyalkyleneglycoxy (e.g., polyethyleneglycoxy), imino, polyimino, branched or unbranched alkenyl, branched or unbranched alkynyl, aryl, heteroaryl, heterocyclyl, nitro, nitrile, thiyl, or carbonyl groups, any of which can be substituted or unsubstituted. Any organic or inorganic counterion can be present in the foregoing charged species, for example an alkali metal, alkaline earth metal, ammonium, or a substituted ammonium of the formula R4N+wherein each R is the same or different, and is independently a Ci-18 hydrocarbyl, provided that that least one R is hydrocarbyl.

[0077] In aspects of the invention, the electroactive species comprises a substituted or unsubstituted quinone of structure (I) or (II):wherein R1, R2, R3, and R4are independently at each occurrence hydrogen, halogen (e.g., chloro, bromo, iodo), hydroxyl, carboxylate / carboxylic acid, sulfonate / sulfonic acid, alkylsulfonate / alkylsulfonic acid, phosphonate / phosphonic acid, alkylphosphonate / alkylphosphonic acid, acyl (e.g., acetyl or ethyl ester), amino, amido, quaternary ammonium (e.g., tetraalkylamino), branched or unbranched Ci-i8 alkyl, heteroalkyl, alkoxy, glycoxy, polyalkyleneglycoxy (e.g., polyethyleneglycoxy), imino, polyimino, branched or unbranched alkenyl, branched or unbranched alkynyl, aryl, heteroaryl, heterocyclyl, nitro, nitrile, thiyl, or carbonyl groups, any of which can be substituted or unsubstituted, and any two adjacent R'-R4groups can optionally join together to form a cyclic group.

[0078] In aspects of the invention, the electroactive organic compound can comprise a quinone, here defined as a cyclic, conjugated system having an even number of carbonyl groups that can be reduced in the manner shown below to form the corresponding aromatic species.

[0079] These include derivatives of 1,4-benzoquinone, 1,2-benzoquinone, naphthoquinone, anthraquinone, phenanthrenequinone, benzanthraquinone, dibenzoanthraquinone, 4,5,9,10- pyrenetetrone, or a combination thereof. Any of the foregoing can optionally be substituted as described above. In aspects of the invention, the electroactive organic compound is a substituted or unsubstituted naphthoquinone. Other regioisomers of the foregoing non-limiting exemplary electroactive organic compounds can also be used (e.g., with substituents at different positions of the quinone).

[0080] In aspects of the invention, the electroactive species comprises the electroactive polymer. As used herein, the term “polymer” refers to structures having greater than 10 repeatingunits. For example, an electroactive polymer can comprise repeating units including any of the foregoing electroactive organic compounds. Suitable electroactive polymers can include, for example, those comprising repeating units derived from a substituted or unsubstituted quinone. In aspects of the invention, at least a portion of the electroactive polymer comprises a polymer backbone wherein at least one of the electroactive organic compounds is covalently bound to the polymer backbone. In aspects of the invention, the electroactive organic compounds can form at least a portion of the polymer backbone.

[0081] In aspects of the invention, the electroactive polymer comprises repeating units derived from a quinone, which as described above can include 1,4-benzoquinone, 1,2- benzoquinone, naphthoquinone, anthraquinone, phenanthrenequinone, benzanthraquinone, dibenzoanthraquinone, 4,5,9, 10-pyrenetetrone, or a combination thereof.

[0082] In aspects of the invention, the electroactive polymer can comprise substituted or unsubstituted poly (anthraquinone). In aspects of the invention, the electroactive polymer can comprise a substituted or unsubstituted poly(vinyl anthraquinone). In aspects of the invention, the electroactive polymer can comprise a substituted or unsubstituted poly(phenylnaphthoquinone).

[0083] In aspects of the invention, the electroactive species comprises the electroactive oligomer. As used herein, the term “oligomer” refers to structures having 2 to 10 repeating units. The electroactive oligomer can accordingly have any structure as described for the electroactive polymer, except that it is limited to 10 repeat units or less. For example, suitable electroactive oligomers can include those comprising repeating units derived from a substituted or unsubstituted quinone, preferably an oligomer comprising repeating units derived from 1,4-benzoquinone, 1,2- benzoquinone, naphthoquinone, anthraquinone, phenanthrenequinone, benzanthraquinone, dibenzoanthraquinone, 4,5,9, 10-pyrenetetrone, or a combination thereof. In aspects of the invention, the electroactive oligomer can comprise oligo(anthraquinone). In aspects of the invention, the electroactive oligomer can comprise an oligo(vinyl anthraquinone). In aspects of the invention, the electroactive oligomer can comprise a substituted or unsubstituted oligo(phenylnaphthoquinone).

[0084] When the electroactive species comprises the electroactive polymer or the electroactive oligomer, the electroactive polymer or the electroactive oligomer can optionally be crosslinked. Crosslinking can be effected by various methods generally known in the ail. Theskilled person, with the benefit of this disclosure, would be able to determine a suitable crosslinking chemistry based on the selection of the electroactive species.

[0085] The electroactive species is reactive toward a target gas. The target gas is an electrophilic molecule. In aspects of the invention, the target gas is a Lewis acid gas. The target gas is capable of forming a complex or an adduct with the electroactive species of the composite when the electroactive species is in a reduced state, for example, by bonding to the electroactive species in its reduced state. The target gas can comprise carbon dioxide (CO2), a sulfur oxide species such as sulfur dioxide (SO2) or sulfur trioxide (SO3), an organosulfate (R2SO4, where each R is independently hydrogen, C1-12 alkyl, or C6-20 aryl) such as dimethyl sulfate, a nitrogen oxide species such as nitrogen dioxide (NO2) or nitrogen trioxide (NO3), a phosphate ester (R3PO4, where each R is independently hydrogen, C1-12 alkyl, or C6-20 aryl) such as trimethyl phosphate, an ester (RCOOR' where each R is independently hydrogen, C1-12 alkyl, or C6-20 aryl, and each R' is independently Ci-12 alkyl or C6-20 aryl) such as methyl formate or methyl acrylate, an aldehyde (RCHO, where each R is independently hydrogen, C1-12 alkyl, or C6-20 aryl ) such as formaldehyde or acrolein, a ketone (R2CO, where each R is independently hydrogen, C1-12 alkyl, or C6-20 aryl) such as acetone, an isocyanate (RNCO, where each R is independently hydrogen, C1-12 alkyl, or Ce- 20 aryl, and each R' is independently C1-12 alkyl or C6-20 aryl) such as methyl isocyanate, isothiocyanate (RNCS, where each R is independently hydrogen, C1-12 alkyl, or C6-20 aryl, and each R' is independently C1-12 alkyl or C6-20 aryl), a borane (BR3, where each R is independently hydrogen, C1-12 alkyl, or C6-20 aryl) such as trimethyl borane, or a borate (R3BO3, where each R is independently hydrogen, Ci-12 alkyl, or C6-20 aryl) such as trimethyl borate. The target gas can optionally comprise a combination of any of the foregoing target gas species.

[0086] The electrochemical cell further includes a counter electrode 920a including a complementary electroactive layer, a first separator 930a between the working electrode and the counter electrode, and an electrolyte. In aspects of the invention the working electrode and the counter electrode can be identical in configuration or composition to provide a symmetric electrochemical cell. The electroactive species in a reduced state bonds with the Lewis acid gas to form an anion adduct of the electroactive species and the Lewis acid gas, thereby effectively removing at least a portion of the Lewis acid gas from the fluid mixture.

[0087] The separator of the electrochemical cell can comprise any suitable material. In aspects of the invention, the separator can be a porous separator. The porous separator can comprise a polymer film, for example a film comprising a polyamide, a polyolefin, a polyaramid, a polyester, a polyurethane, an acrylic resin, and the like, or a combination thereof. The polymer may be coated on one or both sides with ceramic nanoparticles. In aspects of the invention, the porous separator can comprise cellulose, a synthetic polymeric material, or a polymer / ceramic composite material. Further examples of separators can include polyvinylidene difluoride (PVDF) separators, polytetrafluoroethylene (PTFE), PVDF-alumina composite separators, and the like.

[0088] The electrochemical cells can further include an electrolyte. In aspects of the invention the electrolyte is a non-aqueous electrolyte. The non-aqueous electrolyte may be a solid or a liquid having a suitable conductivity at room temperature (e.g., 23°C). The non-aqueous electrolyte may be an organic electrolyte (e.g., N, N-dimethylformamide, liquid quinones), an ionic liquid, a liquid eutectic mixture of organic materials, or a combination thereof. One example of liquid quinones that may be suitable for the methods and systems herein is a liquid mixture of benzoquinone and a second quinone such as a naphthoquinone as is described in Shimizu A, Takenaka K, Handa N, Nokami T, Itoh T, Yoshida JI. Liquid Quinones for Solvent-Free Redox Flow Batteries, Advanced. Materials. 2017 Nov; 29(41); 1606592, the content of which is incorporated herein by reference in its entirety. In one or more aspects, a liquid mixture of benzoquinone and a second quinone such as a naphthoquinone can be used for both the electroactive species and the non-aqueous electrolyte. In some aspects, the non-aqueous electrolyte includes a carbonate ester. For example, in some aspects, the non-aqueous electrolyte may include dimethyl carbonate, diethyl carbonate, ethyl-methyl carbonate, ethylene carbonate, propylene carbonate, or a combination thereof.

[0089] In aspects of the invention, the organic electrolyte can include an organic solvent and a supporting electrolyte. Exemplary organic solvents include, but are not limited to, acetonitrile, dimethylformamide, propylene carbonate, dimethylsulfoxide, polyethylene glycol, diglyme, or a combination thereof.

[0090] The electrolyte can further include a supporting electrolyte. The supporting electrolyte is commonly a quaternary ammonium salt because of its electrical characteristics such as superior electric conductivity in a non-aqueous electrolyte and the like. Examples of the quaternaryammonium salt include, for example, (CH3)4N-BF4, (CH3)3C2H5N BF4, (CH3)2(C2H5)2N-BF4, CH3(C2H5)3N BF4, (C2H5)4N BF4, (C3H7)4N-BF4, CH3(C4H9)3N BF4, (C4H9)4N-BF4, (C6H13)4N-BF4, (C2H5)4N C1O4, (C2H5)4N-BF4, (C2H5)4N-PF6, (C2H5)4N-ASF6, (C2H5)4N-SbF6, (C2H5)4N CF3SO3, (C2H5)4N C4F9SO3, (C2H5)4N (CF3SO2)2N, (C2H5)4N BCH3(C2H5)3,(C2H5)4N- B(C2H5)4, (C2H5)4N- B(C4H9)4, (CTHSFN ■ BiCeH R and the like, hexafluorophosphates thereof, and the like. The supporting electrolyte can be present in an amount of 0 to 70 wt%, based on the total weight of the non-aqueous electrolyte.

[0091] In aspects of the invention, the electrolyte includes an ionic liquid, for example a room temperature ionic liquid (RTIL). Ionic liquids, also referred to as molten salts because they are liquid at room temperature, e.g., 23°C, can have low volatility, for example a vapor pressure of less than 10‘5Pascal (Pa), or IO'10to 10‘5Pa at a temperature of 23°C, which can reduce the risk of the separator drying out, and allow for reduction in loss of the electrolyte due to evaporation or entrainment. In aspects of the invention the ionic liquid accounts for substantially all (e.g., at least 80 volume percent (vol%), or at least 90 vol%, or at least 95 vol%, or at least 98 vol%, at least 99 vol%, or at least 99.9 vol%) of the non-aqueous electrolyte.

[0092] The ionic liquid includes an anion component and a cation component. The anion of the ionic liquid can include, but is not limited to, one or more of halide, sulfate, sulfonate, carbonate, bicarbonate, phosphate, nitrate, nitrate, acetate, Ph),. BF4, trifluoromethanesulfonate (triflate), nonaflate, bis(trifluoromethylsulfonyl)amide, bis(trifluoromethanesulfonyl)imide, trifluoroacetate, heptafluororobutanoate, haloaluminate, triazolide, or an amino acid derivative (e.g., proline with the proton on the nitrogen removed). The cation of the ionic liquid can include, but is not limited to, one or more of imidazolium, pyridinium, pyrrolidinium, phosphonium, ammonium, sulfonium, thiazolium, pyrazolium, piperidinium, triazolium, pyrazolium, oxazolium, guanidinium, an alkali cation, or dialkylmorpholinium. In aspects of the invention, the room temperature ionic liquid includes an imidazolium as a cation component. In aspects of the invention, the room temperature ionic liquid includes l-butyl-3-methylimidazolium (“Bmim”) as a cation component. In aspects of the invention, the room temperature ionic liquid includes bis(trifluoromethyl- sulfonyl)imide (“TFSI”) as an anion component. In aspects of the invention, the room temperature ionic liquid includes l-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide 1(“[Bmim][TFSI]”). In aspects of the invention, the room temperature ionic liquid includes 1-butyl- 3-methylimidazolium tetrafluoroborate (“BF4”) (“[Bmim][BF4]”).

[0093] In aspects of the invention, the electrolyte includes an ionic liquid that may include an unsubstituted or substituted imidazolium, an unsubstituted or substituted morpholinium, unsubstituted or substituted pyridinium, an unsubstituted or substituted pyrrolidinium, an unsubstituted or substituted piperidinium, an unsubstituted or substituted piperazinium, an unsubstituted or substituted pyrazinium, or a combination thereof. In a particular aspect, the ionic liquid may be l-ethyl-3-methylimidazolium bis(trifhioromethanesulfonyl)imide, l-ethyl-3- methylimidazolium bis(fluorosulfonyl)imide, 1 -ethyl-3-methylimidazolium bis(pentafhiorosulfonyl)imide, l-ethyl-3-methylimidazolium dicyanamide, l-ethyl-3- methylimidazolium tetrafluoroborate, l-butyl-3-methylimidazolium bis(trifluoromethyl- sulfonyl)imide, l-butyl-3-methylpyridinium bis(trifluoromethyl-sulfonyl)imide, N-methyl-N- propylpiperidinium bis(trifluoromethanesulfonyl)imide, or a combination thereof.

[0094] In aspects of the invention the separator can be partially or completely impregnated with the electrolyte. Impregnating the separator with the electrolyte can be by submerging, coating, dipping, or otherwise contacting the separator with the electrolyte. Some or all of the pores of the porous separator can be partially or completely filled with the electrolyte. In aspects of the invention, the separator can be saturated with the electrolyte.

[0095] The counter electrode of the electrochemical cell comprises a complementary electroactive layer. The complementary electroactive composite layer comprises a second electroactive species which can be the same or different as the electroactive species of the working electrode.

[0096] In aspects of the invention, the complementary electroactive composite layer comprises the same electroactive species as the composite of the working electrode. In aspects of the invention, the complementary electroactive composite layer comprises a second electroactive species which is different from the first electroactive species of the composite of the working electrode. In aspects of the invention the second electroactive species of the complementary electroactive composite layer can be an electroactive organic molecule, an electroactive polymer, an electroactive oligomer, an electroactive inorganic complex, an electroactive metallocene, or acombination thereof. The electroactive organic molecule, electroactive polymer, and electroactive oligomer can be as previously described.

[0097] In aspects of the invention, the second electroactive species can be an electroactive inorganic complex, for example an alkali metal-transition metal oxide or an alkali metal-transition metal phosphate of the formulaAM’X wherein A is Li, Na, or K; M1is Ni, Co, Mn, Al, Ti, Mo, Fe, V, Si, or a combination thereof; and X is O2 or PO4. In aspects of the invention, the second electroactive species can be LiFcPCL.

[0098] In aspects of the invention, the second electroactive species of the complementary electroactive composite layer comprises a metallocene. An example of a suitable metallocene can include, but is not limited to ferrocene, or a polymer comprising repeating units derived from femocene (e.g., polyvinyl ferrocene), or derivatives thereof.

[0099] During operation of the electrochemical cell, the second electroactive species of the complementary electroactive composite layer can serve as a source of electrons for the reduction of the first electroactive active species of the working electrode. Likewise, the second electroactive species of the complementary electroactive composite layer can serve as a sink for electrons during the oxidation of the first electroactive species of the working electrode.

[0100] In aspects of the invention, the counter electrode can further comprise a substrate, which can be positioned proximate to or between complementary electroactive composite layers. The substrate can be in direct or indirect contact with the complementary electroactive composite layer or layers. When present, the substrate can include, for example, carbon paper (treated, TEFLON-treated, or untreated), carbon cloth, nonwoven carbon mat, or a nonwoven carbon nanotube mat. In aspects of the invention, the support can comprise the same material as the support of the working electrode. In aspects of the invention, the substrate of the counter electrode can be a conductive material and act as a current collector within the electrochemical cell.

[0101] In aspects of the invention, the working electrode can be a negative electrode, and the counter electrode can be a positive electrode. The terms negative electrode and positive electrode are used for convenience and clarity, although they may be technically accurate only when the target gas is being acquired or released.

[0102] In aspects of the invention, the counter electrode can be positioned between working electrodes. In aspects of the invention the working electrodes and / or counter electrodes can be identical in configuration or composition.

[0103] In aspects of the invention, the electrochemical cell comprises a single separator, disposed between the working electrode and the counter electrode, e.g., between the negative electrode and the positive electrode. Electrochemical cells can be combined to make a stack in any suitable combination of parallel and series configurations. In aspects of the invention, the electrochemical cell can comprise more than one separator. For example, one of skill in the art would understand that depending on the selected combination of series and parallel configurations, a single separator may be used, or a plurality of separators may be preferred.

[0104] The electrochemical cell can optionally further comprise a gas permeable layer. The gas permeable layer can be positioned adjacent to the first electrode, on a side opposite the separator. The gas permeable layer can comprise a conductive solid material and act as a current collector within the cell. The gas permeable layer can comprise a porous material. In aspects of the invention, the gas permeable layer has a porosity, for example, of greater than or equal to 60%, greater than or equal to 70%, greater than or equal to the 75%, greater than or equal to 80%, or greater. In aspects of the invention, the gas permeable layer has a porosity of less than or equal to 85%, less than or equal to 90%, or more. Combinations of these ranges are possible. For example, in aspects of the invention, the gas permeable layer of the first electrode has a porosity of greater than or equal to 60% and less than or equal to 90%. Other porosities are also possible. Examples of suitable materials for the gas permeable layer include, without limitation, carbon paper (treated, TEFEON-treated, or untreated), carbon cloth, and nonwoven carbon mat.

[0105] The electrochemical cell can optionally further comprise a gas flow field. The gas flow field, when present, can be positioned adjacent to the gas permeable layer, on a side opposite the first electrode. When the gas permeable layer is not present in the electrochemical cell, the gas flow field can be positioned adjacent to the first electrode, on a side opposite the separator.

[0106] Many of the functional units of the systems described in this specification have been labeled as modules. Embodiments of the invention apply to a wide variety of module implementations. For example, a module can be implemented as a hardware circuit including custom VLSI circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, orother discrete components. A module can also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like. Modules can also be implemented in software for execution by various types of processors. An identified module of executable code can, for instance, include one or more physical or logical blocks of computer instructions which can, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but can include disparate instructions stored in different locations which, when joined logically together, function as the module and achieve the stated purpose for the module.

[0107] The various components / modules / models of the systems illustrated herein are depicted separately for ease of illustration and explanation. In embodiments of the invention, the functions performed by the various components / modules / models can be distributed differently than shown without departing from the scope of the various embodiments of the invention describe herein unless it is specifically stated otherwise.

[0108] Various embodiments of the invention are described herein with reference to the related drawings. Alternative embodiments of the invention can be devised without departing from the scope of this invention. Various connections and positional relationships (e.g., over, below, adjacent, etc.) are set forth between elements in the following description and in the drawings. These connections and / or positional relationships, unless specified otherwise, can be direct or indirect, and the present invention is not intended to be limiting in this respect. Accordingly, a coupling of entities can refer to either a direct or an indirect coupling, and a positional relationship between entities can be a direct or indirect positional relationship. Moreover, the various tasks and process steps described herein can be incorporated into a more comprehensive procedure or process having additional steps or functionality not described in detail herein.

[0109] In some embodiments, various functions or acts can take place at a given location and / or in connection with the operation of one or more apparatuses or systems. In some embodiments, a portion of a given function or act can be performed at a first device or location, and the remainder of the function or act can be performed at one or more additional devices or locations.

[0110] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and / or groups thereof.

[0111] The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the ail without departing from the scope and spirit of the disclosure. The embodiments were chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.

[0112] The diagrams depicted herein are illustrative. There can be many variations to the diagram or the steps (or operations) described therein without departing from the spirit of the disclosure. For instance, the actions can be performed in a differing order or actions can be added, deleted or modified. Also, the term “coupled” describes having a signal path between two elements and does not imply a direct connection between the elements with no intervening elements / connections therebetween. All of these variations are considered a part of the present disclosure.

[0113] The following definitions and abbreviations are to be used for the interpretation of the claims and the specification. As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” “contains” or “containing,” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, a mixture, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such composition, mixture, process, method, article, or apparatus.

[0114] Additionally, the term “exemplary” is used herein to mean “serving as an example, instance or illustration.” Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms “at least one” and “one or more” are understood to include any integer number greater than or equal to one, i.e. one, two, three, four, etc. The terms “a plurality” are understood to include any integer number greater than or equal to two, i.e. two, three, four, five, etc. The term “connection” can include both an indirect “connection” and a direct “connection.”

[0115] The terms “about,” “substantially,” “approximately,” and variations thereof, are intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ± 8% or 5%, or 2% of a given value.

[0116] The present invention may be a system, a method, and / or a computer program product at any possible technical detail level of integration. The computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present invention.

[0117] The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire.

[0118] Computer readable program instructions described herein can be downloaded to respective computing / processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and / or a wireless network. The network may comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and / or edge servers. A network adapter card or network interface in each computing / processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing / processing device.

[0119] Computer readable program instructions for carrying out operations of the present invention may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, configuration data for integrated circuitry, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++, or the like, and procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions may execute entirely on the user’s computer, partly on the user’s computer, as a standalone software package, partly on the user’ s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user’s computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instruction by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present invention.

[0120] Aspects of the present invention are described herein with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of theflowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer readable program instructions.

[0121] These computer readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and / or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function / act specified in the flowchart and / or block diagram block or blocks.

[0122] The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0123] The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the blocks may occur out of the order noted in the Figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and / or flowchart illustration, and combinations of blocks in the block diagrams and / or flowchart illustration, can be implemented by special purpose hardware-based systems that performthe specified functions or acts or carry out combinations of special purpose hardware and computer in stractions.EXAMPLES.Comparative Example 1

[0124] A seven-cell ESA stack was charged and discharged using a target charge voltage of 1.2V per cell and target discharge voltage of -0.1V per cell. The voltage for each cell is shown in FIG. 10. On charge the actual voltage of each cell was between 1.1V and 1.3V, thus some cells experienced an overvoltage condition. On discharge, the actual voltage of each cell was 0.05V to - 0.4V, and thus some cells experienced an over discharge condition.Example 1A controller comprising the circuit shown in FIG. 7 connected to each cell of the seven cell stack used in Comparative Example 1, was used to control the cell voltage. The stack was charged and discharged using a target charge voltage of 1.2V and target discharge voltage of -0.1V. Ten charge cycles, and ten discharge cycles were completed with the controller off, and then controller was turned on. With the controller off, the voltage control was similar to Comparative Example 1, with some cells experiencing overvoltage and undcrvoltagc conditions. With the controller on, the voltage control is improved, as is further illustrated in FIG. 11, which shows the last charge and discharge cycle with the controller off, and the first charge and discharge cycle with the controller on. FIG. 12 illustrates a region 1202 encompassing the transition from controller off to controller on. With the controller off, the cell voltage varied by greater than 100 mV, whereas with the controller on the cell voltage was controlled to within 3mV.

[0125] The disclosure includes the following non-limiting aspects.

[0126] Aspect 1: A controller operable to perform electrochemical cell management operations, the electrochemical cell management operations comprising: based at least in part on a determination that a first electrochemical cell of an electrochemical cell stack has not reached a target voltage, controlling a current to pass through the electrochemical cell system including the first electrochemical cell; and based at least in part on a determination that the first electrochemical cell of the electrochemical cell stack has reached the target voltage, controlling the current tosubstantially bypass the first electrochemical cell and pass through portions of the electrochemical cell stack that are not bypassed.

[0127] Aspect 2: The controller of aspect 1, where: the target voltage comprises a target charge voltage; and the current comprises a charge current.

[0128] Aspect 3: The controller of aspect 1, where: the target voltage comprises a target discharge voltage; and the current comprises a discharge current.

[0129] Aspect 4: The controller of aspect 1, where the electrochemical cell management operations further comprise: controlling a charge stage of the electrochemical cell system such that the target voltage comprises a target charge voltage and the current comprises a charge current; and controlling a discharge stage of the electrochemical cell system such that the target voltage comprises a target discharge voltage and the current comprises a discharge current.

[0130] Aspect 5: The controller of aspect 1 or 4, wherein: an overvoltage state of the first electrochemical cell comprises a first overvoltage of the first electrochemical cell extending beyond the target voltage; and an undervoltage state of the first electrochemical cell comprises the first undervoltage of the first electrochemical cell being less than the target voltage.

[0131] Aspect 6: The controller of any of aspects 1 to 5, wherein the electrochemical cell management operations further comprise: based at least in part on a determination that a second electrochemical cell of the electrochemical cell system has not reached the target voltage, controlling the current to pass through the electrochemical cell system including the second electrochemical cell; and based at least in part on a determination that the second electrochemical cell of the electrochemical cells system has reached the target voltage, controlling the current to substantially bypass the second electrochemical cell and pass through portions of the electrochemical cell system that are not bypassed.

[0132] Aspect 7: The controller of aspect 6, wherein the current adjusts a charge state of the first electrochemical cell at a different rate than the current adjusts a charge state of the second electrochemical cell.

[0133] Aspect 8: The controller of aspect 6, wherein the electrochemical cell management operations are applied concurrently to the first electrochemical cell and the second electrochemical cell.

[0134] Aspect 9: The controller of aspect 6, wherein: the target voltage applied to the first electrochemical cell comprise a first stepped target charge voltage and a first stepped target discharge voltage; and the target voltage applied to the second electrochemical cell comprise a second stepped target charge voltage and a second stepped target discharge voltage.

[0135] Aspect 10: The controller of aspect 9, wherein: the first stepped target charge voltage comprises a first set of target voltages; the first stepped target discharge voltage comprises a second set of target voltages; the second stepped target charge voltage comprises a third set of target voltages; and the second stepped target discharge voltage comprises a fourth set of target voltages.

[0136] Aspect 11: The controller of aspect 10, wherein a first voltage in the first set of target voltages is operable to initiate a capture of a first gas species by the first electrochemical cell; a second voltage in the first set of target voltages is operable to initiate a capture of a second gas species by the first electrochemical cell; a first voltage in the second set of target voltages is operable to initiate a release of the first gas species by the first electrochemical cell; and a second voltage in the second set of target voltages is operable to initiate a release of the second gas species by the first electrochemical cell.

[0137] Aspect 12: The controller of aspect 11, wherein a first voltage in the third set of target voltages is operable to initiate a capture of a third gas species by the second electrochemical cell; a second voltage in the third set of target voltages is operable to initiate a capture of a fourth gas species by the second electrochemical cell; a first voltage in the fourth set of target voltages is operable to initiate a release of the third gas species by the second electrochemical cell; and a second voltage in the fourth set of target voltages is operable to initiate a release of the fourth gas species by the second electrochemical cell.

[0138] Aspect 13: The controller of any of aspects 1 to 12, wherein the first electrochemical cell comprises an electroactive species, which is capable of bonding with a target species.

[0139] Aspect 14: The controller of aspect 13, wherein: the first electrochemical cell comprises a first electrode operable to, responsive to a first selection of the first electrode, bond the target species; and the first electrode is further operable to, responsive to a second selection of the first electrode, release the target species.

[0140] Aspect 15: The controller of aspect 14, wherein the charge management operations further comprise performing the first selection or the second selection.

[0141] Aspect 16: The controller of aspect 15, wherein: performing the first selection comprises controlling an application of a first selection voltage across the first electrochemical cell; and performing the second selection comprises controlling an application of a second selection voltage across the first electrochemical cell.

[0142] Aspect 17: The controller of aspect 16, wherein: controlling the application of the first selection voltage across the first electrochemical cell comprises maintaining a magnitude of the first selection voltage across the first electrochemical cell; and controlling the application of the second selection voltage across the first electrochemical cell comprises maintaining a magnitude of the second selection voltage across the first electrochemical cell.

[0143] Aspect 18: The controller of aspect 17, wherein the first electrode comprises an electroactive species capable of bonding with the target species when the electroactive species is in a first oxidation state and releasing the target species when the electroactive species is in a second oxidation state.

[0144] Aspect 19: The controller of aspect 18, wherein the first electrochemical cell further comprises a first complementary electroactive composite layer, and a first separator between the first electrode and the first complementary electrode.

[0145] Aspect 20: The controller of any of aspects 18 to 19, wherein the electroactive species comprises an electroactive polymer, an electroactive oligomer, an electroactive organic compound, an electroactive inorganic complex, an electroactive organometallic complex, or a combination thereof.

[0146] Aspect 21: The controller of aspect 20, wherein the electroactive species has a binding constant with the target species of at least 101M’1, preferably 101to IO20M'1, more preferably 103to IO20.

[0147] Aspect 22: The controller of any of aspects 13 to 21, wherein the target species comprises a Lewis acid gas.

[0148] Apsect 23: The controller of any of aspects 13 to 22, wherein the target species comprises CO2 or SO2.

[0149] Aspect 24: A gas separation system comprising the controller of any of aspects 1 to 23 in fluidic communication with a gas inlet and a gas outlet.

[0150] Aspect 25: The gas separation system of aspect 24, wherein a fluid mixture comprises the target species.

[0151] Aspect 26: The gas separation system of aspect 25, wherein the fluid mixture is a target gas stream.

[0152] Aspect 27: A system comprising: an electrochemical cell comprising: a working electrode comprising an electroactive species having a first oxidation state at a first applied voltage and a second oxidation state at a second applied voltage; a counter electrode; and a separator between the working electrode and the counter electrode; and the controller of any of aspects 1 to 26 controlling the charging current to the electrochemical cell.

[0153] Aspect 28: The system of aspect 27, wherein the controller comprises a current controller configured to provide the first applied voltage or the second applied voltage between the working electrode and the counter electrode.

[0154] The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the ail to understand the embodiments described herein.

Claims

CLAIMS1. A controller operable to perform electrochemical cell management operations, the electrochemical cell management operations comprising: based at least in part on a determination that a first electrochemical cell of an electrochemical cell stack has not reached a target voltage, controlling a current to pass through the electrochemical cell system including the first electrochemical cell; and based at least in part on a determination that the first electrochemical cell of the electrochemical cell stack has reached the target voltage, controlling the current to substantially bypass the first electrochemical cell and pass through portions of the electrochemical cell stack that are not bypassed.

2. The controller of claim 1, where: the target voltage comprises a target charge voltage; and the current comprises a charge current.

3. The controller of claim 1, where: the target voltage comprises a target discharge voltage; and the current comprises a discharge current.

4. The controller of claim 1 , where the electrochemical cell management operations further comprise: controlling a charge stage of the electrochemical cell system such that the target voltage comprises a target charge voltage and the current comprises a charge current; and controlling a discharge stage of the electrochemical cell system such that the target voltage comprises a target discharge voltage and the current comprises a discharge current.

5. The controller of claim 1, wherein: an overvoltage state of the first electrochemical cell comprises a first overvoltage of the first electrochemical cell extending beyond the target voltage; and an undervoltage state of the first electrochemical cell comprises the first undervoltage of the first electrochemical cell being less than the target voltage.

6. The controller of claim 1, wherein the electrochemical cell management operations further comprise: based at least in part on a determination that a second electrochemical cell of theelectrochemical cell system has not reached the target voltage, controlling the current to pass through the electrochemical cell system including the second electrochemical cell; and based at least in part on a determination that the second electrochemical cell of the electrochemical cells system has reached the target voltage, controlling the current to substantially bypass the second electrochemical cell and pass through portions of the electrochemical cell system that are not bypassed.

7. The controller of claim 6, wherein the current adjusts a charge state of the first electrochemical cell at a different rate than the current adjusts a charge state of the second electrochemical cell.

8. The controller of claim 6, wherein the electrochemical cell management operations are applied concurrently to the first electrochemical cell and the second electrochemical cell.

9. The controller of claim 6, wherein: the target voltage applied to the first electrochemical cell comprise a first stepped target charge voltage and a first stepped target discharge voltage; and the target voltage applied to the second electrochemical cell comprise a second stepped target charge voltage and a second stepped target discharge voltage.

10. The controller of claim 9, wherein: the first stepped target charge voltage comprises a first set of target voltages; the first stepped target discharge voltage comprises a second set of target voltages; the second stepped target charge voltage comprises a third set of target voltages; and the second stepped target discharge voltage comprises a fourth set of target voltages.

11. The controller of claim 10, wherein a first voltage in the first set of target voltages is operable to initiate a capture of a first gas species by the first electrochemical cell; a second voltage in the first set of target voltages is operable to initiate a capture of a second gas species by the first electrochemical cell; a first voltage in the second set of target voltages is operable to initiate a release of the first gas species by the first electrochemical cell; and a second voltage in the second set of target voltages is operable to initiate a release of the second gas species by the first electrochemical cell.

12. The controller of claim 11, wherein a first voltage in the third set of target voltages is operable to initiate a capture of a third gas species by the second electrochemical cell; a second voltage in the third set of target voltages is operable to initiate a capture of a fourth gas species by the second electrochemical cell; a first voltage in the fourth set of target voltages is operable to initiate a release of the third gas species by the second electrochemical cell; and a second voltage in the fourth set of target voltages is operable to initiate a release of the fourth gas species by the second electrochemical cell.

13. The controller of claim 1, wherein the first electrochemical cell comprises an electroactive species, which is capable of bonding with a target species.

14. The controller of claim 13, wherein: the first electrochemical cell comprises a first electrode operable to, responsive to a first selection of the first electrode, bond the target species; and the first electrode is further operable to, responsive to a second selection of the first electrode, release the target species.

15. The controller of claim 14, wherein the charge management operations further comprise performing the first selection or the second selection.

16. The controller of claim 15, wherein: performing the first selection comprises controlling an application of a first selection voltage across the first electrochemical cell; and performing the second selection comprises controlling an application of a second selection voltage across the first electrochemical cell.

17. The controller of claim 16, wherein: controlling the application of the first selection voltage across the first electrochemical cell comprises maintaining a magnitude of the first selection voltage across the first electrochemical cell; and controlling the application of the second selection voltage across the first electrochemical cell comprises maintaining a magnitude of the second selection voltage across the first electrochemical cell.

18. The controller of claim 17, wherein the first electrode comprises an electroactive species capable of bonding with the target species when the electroactive species is in a first oxidation state and releasing the target species when the electroactive species is in a second oxidation state.

19. The controller of claim 18, wherein the first electrochemical cell further comprises a first complementary electroactive composite layer, and a first separator between the first electrode and the first complementary electrode.

20. The controller of claim 18, wherein the electroactive species comprises an electroactive polymer, an electroactive oligomer, an electroactive organic compound, an electroactive inorganic complex, an electroactive organometallic complex, or a combination thereof.

21. The controller of claim 20, wherein the electroactive species has a binding constant with the target species of at least 101M’1, preferably 101to IO20M’1, more preferably 103to IO20.

22. The controller of claim 13, wherein the target species comprises a Lewis acid gas.

23. The controller of claim 13, wherein the target species comprises CO2 or SO2.

24. A gas separation system comprising the controller of claim 1 in fluidic communication with a gas inlet and a gas outlet.

25. The gas separation system of claim 24, wherein a fluid mixture comprises the target species.

26. The gas separation system of claim 25, wherein the fluid mixture is a target gas stream.

27. A system comprising: an electrochemical cell comprising: a working electrode comprising an electroactive species having a first oxidation state at a first applied voltage and a second oxidation state at a second applied voltage; a counter electrode; and a separator between the working electrode and the counter electrode; and the controller of claim Icontrolling the charging current to the electrochemical cell.

28. The system of claim 27, wherein the controller comprises a current controller configured to provide the first applied voltage or the second applied voltage between the working electrode and the counter electrode.

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