Patent Application
20200203703
This patent document relates to a gas fill method and apparatus for the accurate mass delivery of liquefied gas solvent for the preparation of electrochemical energy storage devices.
The energy density of batteries is proportional to the operating voltage. In supercapacitors (i.e., electrochemical double-layer capacitors) the energy density is proportional to voltage squared. With a greater demand for increased energy densities in electrochemical energy storage devices, significant improvements can be made by increasing the voltage ratings of such devices. An important contributing factor to the voltage limitation of electrochemical energy storage devices is the stability of the electrolyte solvent. At increased voltages, the electrolyte solvent may break down and increase in resistance. As a result, loss of charge storage capability (capacity), gassing and device end of life may be reached. Therefore, improving the voltage rating of such devices is highly dependent on the electrolyte system used. Increasing the oxidation resistance of solvents may widen the potential window of the electrolyte, defined as the potential difference between which significant oxidation and reduction current occurs, and can be very useful in electrochemical applications such as batteries, supercapacitors, chemical sensing and common reduction-oxidation electrochemistry.
Conventional electrochemical energy storage devices, such as batteries or capacitors, use electrolyte solutions composed of solvents that are in liquid phase at normal operating temperature and pressure. Recently published prior art has disclosed electrochemical devices utilizing electrolytes with liquefied gas solvents. The introduction of liquefied gas solvents into electrochemical devices may require a different filling process for the electrolyte solution. Conventional electrochemical devices utilizing liquid solvents may use any suitable liquid phase transfer mechanism to fill the device, such as addition of a known volume of electrolyte solution through a pipette. These standard practices are not possible with liquefied gas solvents due to their high vapor pressure, which prevents transfer in the liquid phase at normal temperature and pressure. The prior art discloses a fill process utilizing a mass flow controller or mass flow meter to control the gas flow into the electrochemical device. The prior art also discloses cooling of the electrochemical device to condense the gas into the device.
Gas phase delivery systems requiring accurate flow rate control may utilize mass flow controller (MFC) or mass flow meter (MFM) instruments. Mass flow controllers may be subject to process constraints such as operating pressure, operating temperature, and flow rate dynamic range. Mass flow controllers may also be sensitive to sudden changes in flow and pressure, causing transient deviations from flow set point conditions. These limitations in operation window and stability may be in part due to the control valve attached to the unit. These process constraints make certain MFC instruments undesirable for use in the electrochemical device filling process. Commercial mass flow meter instruments may have wider process windows with respect to MFCs because the MFM may not have an attached control valve. Therefore, a MFM may be more suitable for use in the electrochemical device filling process. The MFM may be coupled with flow and pressure controls that are compatible with the liquefied gas fill process parameters to enable accurate flow monitoring.
A typical pressure control device may be a mechanical gas regulator. Conventional mechanical gas regulators may not be ideal for delivery of gas when the operating pressure is near the source vapor pressure. The regulator output can become unstable during flow when the outlet pressure is close to the inlet pressure. Additionally, mechanical regulators may be sensitive to downstream flow spikes or droop, which can cause flow measurement inaccuracies.
Conventional flow controllers, either manual or electronic, may not be suited for liquefied gas based electrochemical device fill processes due to the limitations in accuracy or operation windows, as discussed above. These limitations in accuracy may also impact the performance of electrochemical devices fabricated using liquefied gas solvents. The prior art has demonstrated the performance of electrochemical devices are greatly affected by the volume of the electrolyte. Deviations in the concentrations of electrolyte components can negatively impact the performance of electrochemical devices. For instance, too little electrolyte may not allow full utilization of all the electrode capacity within the device. Furthermore, too much electrolyte lowers the energy density of the electrochemical device through an increase in mass. It is necessary to prepare an electrochemical device with an accurate electrolyte mass in order to match specified energy densities. Therefore, there is a need for an apparatus and method for the accurate delivery of liquefied gas solvents to electrochemical devices.
Disclosed are novel electrolytes, and techniques for making devices using such electrolytes, which are based on liquefied gas solvents. Unlike conventional electrolytes, disclosed electrolytes are based on “liquefied gas solvents” mixed with various salts, referred to as “liquefied gas electrolytes.” Various embodiments of a liquefied gas solvent include a material that is in a gas phase and has a vapor pressure above an atmospheric pressure at a room temperature. Electrochemical devices such as rechargeable batteries and supercapacitors, which use such liquefied gas electrolytes, are also disclosed. Also disclosed are techniques for electroplating difficult-to-deposit metals or alloys using liquefied gas electrolytes as an electroplating bath. The disclosed liquefied gas electrolytes can have wide electrochemical potential windows, high conductivity, low or high temperature operation capability, high oxidation resistance, and beneficial high pressure solvent or solid electrolyte interfaces (SEI) forming properties.
Conventional electrolytes use solvents that are in liquid phase under normal atmospheric conditions, which are defined as a pressure of 100 kPa, or one atmosphere, and a temperature of 293.15 K, or room temperature. In contrast, disclosed liquefied gas electrolytes use a “liquefied gas solvent” that has a vapor pressure above atmospheric pressure of 100 kPa at room temperature of 293.15 K. Hence, without a properly pressurized environment, such a liquefied gas solvent is often in gas phase, which is not suitable for forming electrolytes.
Methods and structures are disclosed to accurately fill an electrochemical device or cell with a liquefied gas solvent that has a vapor pressure above an atmospheric pressure of 100 kPa at a room temperature of 293.15 K. The method includes providing a fill setup that has a liquefied gas solvent source connected to a flow meter, which in turn is connected to the electrochemical device. A valve structure is included that allows the liquefied gas solvent to flow from the liquefied gas solvent source to the electrochemical device. The connection between the flow meter and the electrochemical device includes a waste volume, a pressure sensor that detects the pressure of the waste volume, and a temperature sensor that detects the temperature of the waste volume. The method includes the following steps: (a) setting a preset amount of the liquefied gas solvent to be delivered to the electrochemical device; (b) actuating the valve structure to allow the flow of the liquefied gas solvent to the electrochemical device; (c) determining the amount of the liquefied gas solvent in the waste volume based on the pressure and temperature sensors; (d) determining the amount of the liquefied gas solvent supplied to the flow meter; and (e) actuating the valve structure to stop the flow of the liquefied gas solvent to the electrochemical device based on the preset amount, the amount determined to be in the waste volume and the amount determined to have been supplied to the flow meter.
The method may include using a reading from the mass flow meter in step (d). The setup may include a mass flow controller, and the method may further include setting the mass flow controller to a preset flow rate, and determining the amount of time the liquefied gas solvent has flowed through the mass flow controller, which would be the basis to determine how much liquefied gas solvent was supplied to the flow meter.
The actuation of the valve structure may be based on a comparison of the amount of liquefied gas solvent determined to have been supplied to the flow meter to the sum of the preset amount and to the amount determined to be in the waste volume.
The fill setup may also include a temperature control element constructed to maintain a variance of temperature within the waste volume to within +/−2.0 degrees Celsius. Similarly, the setup may include a temperature control element constructed to maintain the connection between the liquefied gas solvent source and the flow meter to within +/−2.0 degrees Celsius. The fill setup may also have a pressure regulator or pressure controller constructed to maintain the variance of the connection between the pressurized source and the flow meter to within +/−25 kPA.
The method may be expanded to include a second liquefied gas solvent source. Specifically, the fill setup would further include a second liquefied gas solvent source connected to a flow meter and a second valve structure constructed to allow the liquefied gas solvent to flow from the second liquefied gas solvent source to the electrochemical device. The method would then further include the following steps: (a2) setting a second preset amount of the liquefied gas solvent from the second liquefied gas solvent source to be delivered to the electrochemical device; (b2) actuating the second valve structure to allow the flow of the second liquefied gas solvent to the electrochemical device; (c2) determining the amount of the second liquefied gas solvent in the waste volume based on the pressure and temperature sensors; (d2) determining the amount of the second liquefied gas solvent supplied to the flow meter based on the flow meter; and (e2) actuating the second valve structure to stop the flow of the second liquefied gas solvent to the electrochemical device based on the second preset amount, the amount of the second liquefied gas solvent determined to be in the waste volume and the amount of the second liquefied gas solvent determined to have been supplied to the flow meter. Steps (b2) -(e2) are performed after step (e).
The connection between the flow meter and the electrochemical device may further include a third valve structure and a pump between the third valve structure and the flow meter. The method could then include the following step: prior to performing steps (b2) -(e2), the third valve structure is closed, and the pump is actuated to evacuate the waste volume of the liquefied gas solvent.
The method can be used with liquefied gas solvents selected from the group consisting of: fluoromethane, difluoromethane, trifluoromethane, fluoroethane, tetrafluoroethane, pentafluoroethane, 1,1-difluoroethane, 1,2-difluoroethane, 1,1,1-trifluoroethane, 1,1,2-trifluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,2,2-tetrafluoroethane, pentafluoroethane, chloromethane, chloroethane, thionyl fluoride, thionyl chloride fluoride, phosphoryl fluoride, phosphoryl chloride fluoride, sulfuryl fluoride, sulfuryl chloride fluoride, 1-fluoropropane, 2-fluoropropane, 1,1-difluoropropane, 1,2-difluoropropane, 2,2-fluoropropane, 1,1,1-trifluoropropane, 1,1,2-trifluoropropane, 1,2,2-trifluoropropane, fluoroethylene, cis-1,2-fluoroethylene, 1,1-fluoroethylene, 1-fluoropropylene, 2-propylene, chlorine, chloromethane, bromine, iodine, ammonia, molecular oxygen, molecular nitrogen, carbon monoxide, carbon dioxide, sulfur dioxide, dimethyl ether, nitrous oxide, nitrogen dioxide, nitrogen oxide, carbon disulfide, hydrogen fluoride, hydrogen chloride, combination thereof, and isomers thereof.
Also disclosed is a fill setup with the flow meter, valve structures, pressure sensor, temperature sensor and pump are connected to and controlled by a controller performing the steps just described.
Additional aspects, alternatives and variations as would be apparent to persons of skill in the art are also disclosed herein and are specifically contemplated as included as part of the invention. The invention is set forth only in the claims as allowed by the patent office in this or related applications, and the following summary descriptions of certain examples are not in any way to limit, define or otherwise establish the scope of legal protection.
Reference is made herein to some specific examples of the present invention, including any best modes contemplated by the inventor for carrying out the invention. Examples of these specific embodiments are illustrated in the accompanying figures. While the invention is described in conjunction with these specific embodiments, it will be understood that it is not intended to limit the invention to the described or illustrated embodiments. To the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. Particular example embodiments of the present invention may be implemented without some or all of these specific details. In other instances, process operations well known to persons of skill in the art have not been described in detail in order to not unnecessarily obscure the present invention. Various techniques and mechanisms of the present invention will sometimes be described in singular form for clarity. However, it should be noted that some embodiments include multiple iterations of a technique or multiple mechanisms, unless noted otherwise. Similarly, various steps of the methods shown and described herein are not necessarily performed in the order indicated, or performed at all in certain embodiments. Accordingly, some implementations of the methods discussed herein may include more or fewer steps than those shown or described. Further, the techniques and mechanisms of the present invention will sometimes describe a connection, relationship or communication between two or more entities. It should be noted that a connection or relationship between entities does not necessarily mean a direct, unimpeded connection, as a variety of other entities or processes may reside or occur between any two entities. Consequently, an indicated connection does not necessarily mean a direct, unimpeded connection unless otherwise noted.
The following list of example features corresponds with the attached figures and is provided for ease of reference, where like reference numerals designate corresponding features throughout the specification and figures:
Method of filling an electrochemical device with a liquefied gas solvent that has a vapor pressure above an atmospheric pressure of 100 kPa at a room temperature of 293.15 K
200
Steps of Method 205-255
It is generally agreed that a limiting factor to further extending electrochemical capabilities of electrochemical energy storage devices, such as rechargeable Lithium (Li)-ion batteries (LIB) and electrochemical double layer capacitors (EDLC), is the electrolyte, and intense efforts are being made to improve these systems by expanding the potential window and conductivity over a wide temperature range. Properties that make up a good solvent for electrolytes (e.g., solvent viscosity, permittivity, reduction and oxidation potentials, conductivity, etc.) are well-known and studied for numerous solvents. However, potential windows, defined as the potential difference between which significant oxidation and reduction current occurs, are typically limited to less than ˜4.5 V for the existing electrolyte-based systems. Ionic liquid-based electrolytes offer a promising approach to electrochemical systems, but are still difficult to handle and to manufacture, and often do not perform as well as traditional organic electrolytes. High energy density cathodes that have been developed for next generation Li-ion batteries have yet to be implemented because of the lack of a suitable electrolyte system. Electrochemical double layer capacitors are similarly limited in their energy density due to the limited potential window of the electrolytes.
The vast majority of research efforts on new electrolytes target systems using chemicals that are liquid at room temperature and atmospheric pressure, herein referred to as “liquid solvents.” While convenient to work with, these liquid solvents may not offer the best properties. The use of low molecular weight liquefied gas solvents based on hydrofluorocarbon solvents molecules can be promising candidate solvents in next generation electrolytes. These solvents generally exhibit high oxidation resistance, due to the highly electronegative fluorine groups of these hydrofluorocarbon molecules. Optimization of the conductivity of these liquefied gas solvent systems, which would enable utilization of these electrolytes in batteries and electrochemical double layer capacitors, has not been done. According to some embodiments of this patent disclosure, new data obtained has shown that these electrolyte systems can actually be made highly conductive over a surprisingly broad range of temperatures and can enable the use of these novel solvents in next-generation, significantly higher-capacity energy storage devices.
Large capacity energy storage devices such as Li-ion batteries or supercapacitors are important devices essential for modern engineering and communications devices as well as consumer markets. These devices are described below.
Supercapacitors (or electrochemical capacitors) are made up of two electrodes physically separated by an ion-permeable membrane (often called a separator), immersed in an electrolyte which electrically connects the two electrodes (i.e., cathode and anode). When a voltage is applied and the electrodes are polarized, ions in the electrolyte form electric double layers of opposite polarity to the electrode's polarity. Thus, a positively polarized electrode will have a layer of negative ions forming at the interface between electrode and electrolyte. For charge-balancing, a layer of positive ions adsorb onto the negative layer. For the negatively polarized electrode, the opposite situation is developed.
Typically, the energy density of batteries increases with the operating voltage, and the energy stored electrochemically inside the electrode. In supercapacitors (also referred to as “electrochemical double-layer capacitors” or sometimes as “ultracapacitors”), the energy density is proportional to capacitance times voltage squared, i.e., E=(½)CV2, and energy is stored in the electrostatic attraction between opposite charges in the electrode and in the electrolyte. Therefore, a higher operating voltage is important for achieving higher power in energy storage devices such as supercapacitors and batteries. With a greater demand for increased energy densities in electrochemical energy storage devices, significant improvements can be made by increasing the voltage ratings of such devices.
Based on electrode design, three types of supercapacitors are often used. (1) Electrochemical double-layer capacitors (EDLC) typically use carbon electrodes or related materials. EDLCs exhibit much higher electrostatic double-layer capacitance than electrochemical pseudocapacitance. (2) Electrochemical pseudocapacitors typically use metal oxide or conducting polymer electrodes. (3) Hybrid capacitors have asymmetric electrodes; for example, one electrode exhibiting mostly electrostatic capacitance, while the other electrode showing mostly electrochemical capacitance.
Supercapacitors have energy densities that are approximately one-tenth of the energy densities of conventional batteries, but with fast charge/discharge cycles, their power density can be 10 to 100 times greater that of the batteries. Such a higher power density can be useful, for example, for starting automobile engines. Acetonitrile based electrolytes are advanced electrolytes for EDLC supercapacitors, but they are often flammable and can release cyanide gas upon ignition. Consequently, acetonitrile based electrolytes are not preferred for general automotive applications. Propylene carbonate is considered a good all round solvent, but has a limitation of minimum operating temperature of −25° C. Other electrolytes being developed use ionic liquids. Such electrolytes are very expensive to manufacture, and their low temperature performance tends to be very poor.
The energy density of both Li-ion batteries and supercapacitors is strongly dependent on operating voltage. Additionally, there are some other important aspects that require innovative new concepts to overcome the current barriers. The disclosed liquefied gas solvent-based electrolytes provide solutions to overcome these barriers, which are described below.
(1) A major contributing factor to the voltage limitation of electrochemical energy storage devices is the stability of the electrolyte's solvent. At high oxidizing or reducing voltages, the solvent may break down and increase resistance, and as a result, a loss of charge storage capability (capacity), gassing and device end of life may be reached. Hence, improving the stability of such devices is highly dependent on the electrolyte system used, and the disclosed liquefied gas solvent-based electrolyte system enables a higher voltage operation of the electrochemical energy storage devices.
(2) The ionic conductivity of electrolytes is often lowered by highly viscous solvents or with relatively high melting point solvents. Hence, identifying a solvent, or a mixture of solvents having a low viscosity and a low melting point is important to improve the ionic conductivity of electrolyte systems. The disclosed liquefied gas solvent-based electrolyte system offers improved ionic conductivity.
(3) The solid-electrolyte-interface (SEI) is known to be an important component in common electrochemical energy storage devices, of which the solvent in the electrolyte plays an important role. The SEI is a complex, yet very thin layer (e.g., 10-100 nm in thickness) that forms on the electrode surface from the decomposition products from the battery's electrolyte, often due to side reactions caused mainly by the reduction or oxidation of solvents at the surface. SEI is very sensitive to water and oxygen, and battery degradation with time and charge/discharge cycles is often attributed to the properties of the SEI layer. Identifying solvents that play a beneficial role in the SEI layer formation, and producing SEI layers that are less detrimental to the battery operational cycles and long term battery stability are desired. The disclosed liquefied gas solvent-based electrolyte system offers a possibility of more stable SEI layer formation.
(4) Many electrochemical device applications such as supercapacitors require a high surface area electrode with nanopores that are often inaccessible to the electrolyte due to high surface tension, trapped gas or gas generated within the electrode. An electrolyte with improved accessibility to these nanopores is beneficial to the overall system performance. The disclosed liquefied gas solvent-based electrolyte system offers an easier penetration of electrolytes into nanoporous surfaces by virtue of the higher pressure employed in the liquefied gas solvent-based devices.
(5) Electrodeposition of difficult-to-electroplate metals and alloys such as Ti, Al, Si, and W can be enabled with larger potential windows in electrochemical systems, and therefore it is desirable to find a solvent and electrolyte compositions that can enable electroplating of such metals for a myriad of industrial applications, which also include improved redox electrochemistry and chemical sensing. Enabling of electrodeposition of semiconductors such as Si can offer significant manufacturing and economic advantages for the electronics industry. Enabling of electrodeposition of aluminum, titanium, tungsten and their alloys can have significant industrial and economic impact toward easier and inexpensive surface passivation (e.g., via anodization coating formation for protective or decorative surfaces), corrosion resistance, wear resistance, and environmental cleaning (e.g., in the case of utilizing the advantageous effect of titanium or titanium oxide surface coating for enhanced decomposition of toxic materials or for water purification). The disclosed technology enables electroplating or sensing with higher electrochemical potential windows.
The disclosed technology can increase the potential window of the electrolyte, improve ionic conductivity over a wide temperature range, improve the SEI layers, and improve electrolyte accessibility to nanopores, all of which can be very useful in electrochemical applications such as batteries, supercapacitors, electroplating, chemical sensing and common reduction-oxidation electrochemistry.
Disclosed are novel and advantageous electrolytes, techniques for making, structures and devices using such electrolytes, which are based on liquefied gas solvents in combination with metal-ion containing salt and/or non-metal-ion containing salt.
In the examples in this document, a liquefied gas solvent-based electrolyte or “liquefied gas electrolyte” is a mixture electrolyte that includes a liquefied gas solvent portion and a salt portion which are mixed together under a pressurized condition to form the liquefied gas electrolyte. The composition and manufacture of the gas electrolyte is disclosed in the applications listed above, and incorporated by reference.
The liquefied gas solvent may include fluoromethane, difluoromethane, trifluoromethane, fluoroethane, tetrafluoroethane, pentafluoroethane, 1,1-difluoroethane, 1,2-difluoroethane, 1,1,1-trifluoroethane, 1,1,2-trifluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,2,2-tetrafluoroethane, pentafluoroethane, chloromethane, chloroethane, thionyl fluoride, thionyl chloride fluoride, phosphoryl fluoride, phosphoryl chloride fluoride, sulfuryl fluoride, sulfuryl chloride fluoride, 1-fluoropropane, 2-fluoropropane, 1,1-difluoropropane, 1,2-difluoropropane, 2,2-fluoropropane, 1,1,1-trifluoropropane, 1,1,2-trifluoropropane, 1,2,2-trifluoropropane, fluoroethylene, cis-1,2-fluoroethylene, 1,1-fluoroethylene, 1-fluoropropylene, 2-propylene, chlorine, chloromethane, bromine, iodine, ammonia, molecular oxygen, molecular nitrogen, carbon monoxide, carbon dioxide, sulfur dioxide, dimethyl ether, nitrous oxide, nitrogen dioxide, nitrogen oxide, carbon disulfide, hydrogen fluoride, hydrogen chloride, combination thereof, and isomers thereof.
Accurate and efficient introduction of the gas electrolyte into the electrochemical energy storage devices is critical. Conventional flow controllers, either manual or electronic, may not be suited for liquefied gas based electrochemical device fill processes due to the limitations in accuracy, or to the operation windows, as discussed above. These limitations in accuracy may also impact the performance of electrochemical devices fabricated using liquefied gas solvents. The prior art has demonstrated the performance of electrochemical devices are greatly affected by the volume of the electrolyte. Deviations in the concentrations of electrolyte components can negatively impact the performance of electrochemical devices. For instance, too little electrolyte may not allow full utilization of all the electrode capacity within the device. Furthermore, too much electrolyte lowers the energy density of the electrochemical device through an increase in mass.
The proposed and novel method uses a liquefied gas source, a mass flow meter, and an orifice to flow vapor of the liquefied gas into an electrochemical device. A steady gas flow rate through the orifice is obtained by having choked flow conditions while filling the electrochemical device. Choked flow occurs when the downstream pressure of the orifice is less than approximately one half the upstream pressure. With these pressure conditions satisfied, the flow rate through the orifice is fixed by the sonic velocity of the gas. The flow rate is insensitive to pressure fluctuations downstream of the orifice, provided that choked flow conditions remain. The choked flow rate is dependent upon the pressure upstream of the orifice, the molecular weight of the gas, the gas temperature, and the orifice diameter. The flow can be approximated by Equation 1.
In Equation 1, P1 is the pressure upstream of the orifice in pounds per square inch, M is the molecular weight of the gas, T is the temperature of the gas in degrees Rankine, and d is the orifice diameter in micrometers. Table 1 shows the respective flow rates for fluoromethane in standard cubic centimeters per minute at different upstream pressures and orifice diameters based on the calculations from Equation 1.
An additional “constant” parameter may be included in Equation 1 in conditions where choked flow is not satisfied. Under such conditions, the flow is dependent on the pressure downstream of the orifice.
Further improvements in gas flow accuracy may require temperature control of the apparatus components. The temperature control may be such that the liquefied gas source is at higher temperature relative to the electrochemical device. The electrochemical device may require heat removal through a heat sink and cooling system in order to maintain lower vapor pressure than the liquefied gas source. The liquefied gas source and gas delivery lines may also be heated so that the vapor pressure is increased relative to the pressure in the electrochemical device. Heating the liquefied gas source, gas delivery lines, and MFM may be performed with commercial heating elements including heating blankets, heating rope, heating tape, or circulating air heaters. Electronic MFM instruments may require specific temperature control due to the internal heating from the instrument. Due to the temperature and pressure sensitivity of MFM instruments, the temperature control may be necessary for accurate mass flow readings.
In some embodiments of this invention, the filling process for electrochemical devices may have a preferred flow rate for accurate liquefied gas delivery. The preferred flow rate may depend on the heat removal at the electrochemical device due to heat of condensation of the solvent, and the heat supplied at the liquefied gas source and delivery lines. The preferred flow rate may be necessary for obtaining accurate flow measurements from the mass flow measurement device. The preferred flow rate may be obtained by appropriate sizing of the gas lines, sizing of the orifices, or use of a mass flow controller.
In cases where it is desirable to operate the MFM at pressures below the vapor pressure of the liquefied gas, an orifice upstream of the MFM can be used. The upstream orifice creates a pressure drop during gas flow which is stable across the MFM to the downstream orifice. The pneumatic shut-off valves maintain the operation pressure when flow is stopped; therefore, the process pressure is consistent from one device fill to the next.
An alternative method for pressure control across the MFM is an upstream electronic pressure controller. A pressure controller contains a control valve and integral transducer to maintain steady pressure. A pressure controller may improve pressure stability across the MFM leading to improved liquefied gas fill accuracy.
This method for gas phase delivery of liquefied gas solvents for electrochemical devices may be automated using a CPU to monitor pressure and flow rate, as well as to control pneumatic shut-off valves. The CPU is connected to pressure transducers, both at the electrochemical device, and at the MFM, to ensure that choked flow conditions are sustained during the device fill process. The CPU monitors the MFM flow rate and total solvent mass transferred to the electrochemical device. When the CPU solvent mass monitor reaches the input mass, the CPU closes the pneumatic shut-off valves to stop flow to the electrochemical device. This automated system improves ease of use, efficiency, lowers cost of operation and waste solvent due to rapid calculation of accurate gas addition.
What follows are ten non-limiting examples showing various embodiments of the present invention. One such embodiment is illustrated in
Another embodiment of this invention is illustrated in
What is important to note in
If the electrochemical device 11 is filled at very low temperatures (−70 degrees C.), then the pressure and density of the gas in the waste volume 26 will remain low. If the temperature of the waste volume 26 is accurate to within 1 degree Celsius, then the uncertainty of the mass calculation in the waste volume relative to the mass in the electrochemical device cell would likely be small, yielding a highly accurate electrochemical device fill. If, however, the electrochemical device is filled at high temperatures (0 degrees C.), then the pressure and density of the gas in the waste volume 26 is much higher. Even if the temperature of the waste volume 26 is accurate to within 1 degree Celsius, then the uncertainty of the mass calculation in the waste volume 26 relative to the mass in the electrochemical device 11 will be significantly higher.
Also, when multiple gas solvents are used (see
When the system is loaded with a new electrochemical device which is also being filled with the A+B+C gas combination, then the gram of gas C in the waste volume should be evacuated by closing valves 2 and 10, opening valve 8 and actuating pump 12.
Another embodiment of this invention is illustrated in
Another embodiment of this invention is illustrated in
Another embodiment of this invention is illustrated in
Another embodiment of this invention is illustrated in
Another embodiment of this invention is illustrated in
Another embodiment of this invention is illustrated in
Another embodiment of this invention is illustrated in
Another embodiment of this invention is illustrated in
In another embodiment of this invention, the pressure P2 can exceed one-half the pressure P1. This operating condition may not provide choked flow through an orifice; however, it is still possible to achieve accurate mass fills for liquefied gas solvent into electrochemical devices. In a preferred embodiment the apparatus would only have an orifice downstream of the mass flow meter 5 such as in
An operation process is described for the embodiment shown in
Referring to
The CPU program integrates the MFC flow rate to calculate total mass flow downstream of valve 7 and the mass in the electrochemical device 11. The mass in the electrochemical device 11 is calculated by subtracting the mass contained in the waste volume 26 (i.e., between valve 7 and valve 23) from the total mass flow. The mass that is subtracted out is determined by the pressure in the gas line and the temperature (derived from sensors 9 and 29).
Data tables of the gas density at the operating temperature and pressure are used to precisely determine the density of the gas in the waste volume 26 (i.e., between valve 7 and valve 23). The waste volume is known with high accuracy. Multiplying the density by the volume provides the mass delivered by the MFC but did not go into the electrochemical device. The pressure in the waste volume 26 is not static during the fill; therefore, the amount of gas that gets subtracted from the electrochemical device 11 is updated during the fill process.
When the CPU program calculation for the mass in the electrochemical device 11 reaches the setpoint, valves 2, 7, 10, and 23 are closed, and the tubing between valves 7 and 23 is evacuated.
The process may be repeated if the electrochemical device 11 requires a mixture of liquefied gas solvents. Subsequent liquefied gases delivered to the electrochemical device 11 may require some process modifications to achieve accurate mass delivery. An apparatus, as illustrated in
The mass flow meters and/or mass flow controllers may include, but are not limited to, thermal type flow meters or Coriolis type flow meters. The pressure controllers may include electronic or mechanical pressure controllers, or hybrids thereof. The orifices may include, but are not limited to, a thin metal plate gasket, a nozzle, a restrictor tube, a disc, a fitting, or a control valve. The disclosed apparatuses may consist of 0, 1, 2, or greater than 2 orifices, and the valves may be, but are not limited to, diaphragm valves, needle valves, butterfly valves, ball valves, or gate valves. The liquefied gas solvent source heat source and/or the gas line heat source may be, but are not limited to, a heating blanket, heating tape, heating rope, or thermally regulated enclosures. Likewise, the mass flow meter or mass flow controller heat sources may be, but are not limited to, heating blankets, heating tape, heating rope, or thermally regulated enclosures. The automation and instrument readings may be performed with a data acquisition unit, electronic control panel, PLC, HMI, or similar electronic control devices.
Turning to
The third valve structure may be opened, and the pump may be actuated to evacuate the waste volume 26 (e.g.,
If a third, fourth or greater number of liquefied gas solvents are needed steps 235-255 may be repeated, except that each of the liquefied gas solvent sources would have its own unique valve structure (such as valves 27 and 28 in
While this patent document contains many specifics, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this patent document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.
Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Moreover, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments. Only a few implementations and examples are described and other implementations, enhancements and variations can be made, based on what is described and illustrated in this patent document.
This patent claims priority as a non-provisional of U.S. Patent Application No. 62/911,505 filed on Oct. 7, 2019 entitled “METHOD AND APPARATUS FOR LIQUEFIED GAS SOLVENT DELIVERY FOR ELECTROCHEMICAL DEVICES,” the entire contents of which are incorporated by reference in this document. This patent is related to U.S. patent application Ser. No. 15/036,763 filed on May 13, 2016; International Application No PCT/US2014/066015 filed on Nov. 17, 2014; U.S. Patent Application No. 61/905,057 filed on Nov. 15, 2013; U.S. Patent Application No. 61/972,101 filed on Mar. 28, 2014; International Application No. PCT/US2019/032413 filed on May 15, 2019; U.S. Provisional Application No. 62/673,792 filed on May 18, 2018; U.S. application Ser. No. 15/036,763 filed on May 13, 2016; PCT/US17/29821 filed on Apr. 27, 2017; U.S. application Ser. No. 16/305,034 filed on Nov. 28, 2018; PCT/US2019/032414 filed on May 15, 2019; U.S. Provisional Application No. 62/673,752 filed on May 18, 2018; U.S. Provisional Application No. 62/749,046 filed on Oct. 22, 2018; U.S. Provisional Application No. 61/972,101 filed on Mar. 28, 2014; U.S. Provisional Application No. 61/905,057 filed on Nov. 15, 2013; and U.S. application Ser. No. 16/793,190 filed on Feb. 18, 2020. The entire contents of each of these documents are incorporated by reference in this document.
This invention was made with United States government support by the National Science Foundation, grant number 1831087.
| Number | Date | Country | |
|---|---|---|---|
| 62911505 | Oct 2019 | US |
