A sealed test device and test method for determining gas solubility behavior in electrolytes

Abstract

The application belongs to the technical field of electrochemical detection, and discloses a sealed testing device and a testing method for measuring the gas dissolution behavior in electrolyte, wherein an external to-be-tested gas input end is communicated with a first PEEK two-way valve, and the first PEEK two-way valve is communicated with a pressure sensor through a PEEK pipeline; the pressure sensor is communicated with a glass bottle with a known volume through a PEEK pipeline, and a sealing cover is arranged on the top of the glass bottle with the known volume, and a glass bottle gas inlet and a glass bottle gas outlet are arranged on the sealing cover; the glass bottle gas inlet is communicated with the pressure sensor, and the glass bottle gas outlet is communicated with a second PEEK two-way valve through a PEEK pipeline; and a luer joint and a needle cylinder are sequentially connected to the rear end of the second PEEK two-way valve. The application realizes stable testing of the gas dissolution behavior in electrolyte through manual vacuum extraction, independent gas path control and real-time pressure monitoring, has the advantages of simple structure, good sealing property, strong corrosion resistance and no need of external vacuum pump, and is suitable for laboratory rapid detection, teaching demonstration and other scenes.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical detection technology and discloses a closed testing device and testing method for determining the gas dissolution behavior in electrolytes. It is applicable to the rapid testing of the dissolution behavior of gases such as CO2, H2, and CO in electrolytes under laboratory conditions. Background Technology

[0002] In the study of lithium-ion batteries and other electrochemical systems, the dissolution behavior of gases such as carbon dioxide, hydrogen, and carbon monoxide in the electrolyte directly affects the accuracy of quantitative gas analysis results and the determination of side reaction mechanisms. Therefore, accurate testing of the dissolution behavior of gases in the electrolyte is of great significance.

[0003] Currently, methods for determining gas solubility mainly include differential pressure methods and volumetric methods. Traditional measuring devices are typically complex in structure, requiring large auxiliary equipment such as external vacuum pumps and pressure control systems. For example, common differential pressure method devices require a vacuum pump to evacuate the system, and complex valve switching to achieve gas introduction and pressure monitoring. These devices are not only expensive but also cumbersome to operate, making them unsuitable for rapid on-site testing or educational demonstrations.

[0004] Existing testing methods typically suffer from the following problems: First, the test container lacks sufficient sealing, making it susceptible to interference from external gases. Second, the vacuuming and venting processes are difficult to control independently, hindering precise operation. Third, for small-volume electrolyte systems, if a pressure battery is used as the test container, the electrolyte may affect the gas flow or even cause blockages, which is detrimental to stable testing. Furthermore, existing devices still require improvement in terms of connection structure, corrosion resistance, and ease of reuse.

[0005] Therefore, it is necessary to provide a closed testing device that is simple in structure, has good sealing performance, and is suitable for volume bottle systems, so as to achieve stable testing of gas dissolution behavior in electrolytes. Summary of the Invention

[0006] In order to overcome the shortcomings of the existing technology, the present invention specifically relates to the field of electrolyte gas dissolution behavior testing technology, and provides a sealed testing device based on a volume bottle, which can realize in-situ pressure monitoring and quantitative analysis of the gas dissolution process in the electrolyte, and solve the problems of poor sealing, inconvenient control and easy clogging of the existing devices.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A closed testing device for determining the gas dissolution behavior in an electrolyte, comprising: Intake control module: Configured with an external gas input terminal and a first PEEK two-way valve to realize the on / off control of the gas to be tested; Pressure monitoring module: It adopts a cylindrical pressure sensor, which is connected to the intake control module and the test container through PEEK pipeline to monitor the system pressure changes in real time; Test container module: It uses a glass bottle of known volume, with a sealing cap on the top. The sealing cap has a glass bottle inlet and a glass bottle outlet for holding electrolyte and providing a closed gas phase space. Vacuum control module: includes a second PEEK two-way valve, Luer connector and syringe, which achieves system vacuum by manually pulling the syringe; The external gas input terminal, the first PEEK two-way valve, the pressure sensor, the glass bottle inlet, the glass bottle of known volume, the glass bottle outlet, the second PEEK two-way valve, the Luer connector, and the syringe are connected in series through PEEK tubing to form a complete closed testing system.

[0008] Furthermore, the first PEEK two-way valve is connected to the external gas input terminal, the pressure sensor is connected to the first PEEK two-way valve through a PEEK pipeline, the known volume glass bottle is connected to the pressure sensor through a PEEK pipeline, the glass bottle inlet at the top of the known volume glass bottle is connected to the pressure sensor, the second PEEK two-way valve is connected to the glass bottle outlet through a PEEK pipeline, the Luer connector is connected to the rear end of the second PEEK two-way valve, and the syringe is detachably connected to the Luer connector.

[0009] Furthermore, the glass bottle of known volume is a transparent cylindrical glass bottle, the sealing cap is a disc-shaped sealing cap, and both the air inlet and the air outlet of the glass bottle are located on the sealing cap.

[0010] Furthermore, both the first PEEK two-way valve and the second PEEK two-way valve have a block-shaped valve body structure, and a toggle valve handle is provided on the top of the valve body.

[0011] Furthermore, the Luer connector is a screw-on connection structure.

[0012] Furthermore, all gas connection pipes are made of PEEK material, and all connections are sealed with PEEK fittings.

[0013] Furthermore, the pressure sensor is also connected to an electrochemical workstation for synchronous monitoring of pressure and electrochemical signals during the testing process.

[0014] Furthermore, after the syringe is connected to the Luer connector, it is used to perform evacuation treatment on the entire test system.

[0015] A manual vacuuming method for a closed test device for determining the gas dissolution behavior in an electrolyte is disclosed. The method involves connecting a Luer connector and a syringe via a second PEEK two-way valve and employing a cyclical operation of "pull-close-vent-tighten-open" to repeatedly evacuate a glass bottle of known volume and the front gas path until a vacuum state is achieved.

[0016] A self-testing method for the airtightness of a closed testing device for determining the gas dissolution behavior in an electrolyte involves instantaneously introducing the gas to be tested and monitoring the pressure change; when the equilibrium pressure P2 is stable and greater than atmospheric pressure, it indicates that the system has good airtightness and the gas dissolution has reached equilibrium.

[0017] Furthermore, the glass bottle of known volume is provided with a disc-shaped sealing cap on the top, and the sealing cap is provided with two vertically upward cap-through joints, which serve as the air inlet and air outlet of the glass bottle, respectively. The lower part of each joint is a short and thick cylindrical base, which extends upward into a slender cylindrical connecting section, and the upper part is provided with a screw-on locking cap.

[0018] Furthermore, the Luer connector is an integral multi-step cylindrical shape, with one end connected to the second PEEK two-way valve and the other end detachably connected to the syringe, and a threaded locking part on the outer periphery.

[0019] Furthermore, the PEEK connector is a short cylindrical connector with a multi-step cylindrical structure and locking texture on the surface.

[0020] Furthermore, the syringe has a standard syringe structure, consisting of a transparent cylindrical syringe and an internal piston rod. The front end of the syringe is provided with a tapered connecting nozzle that fits tightly with a Luer connector.

[0021] Furthermore, the device is based on the ideal gas law PV = nRT. Under constant temperature T and gas phase volume V, it calculates the amount of dissolved gas by measuring the pressure difference ΔP before and after gas dissolution. A second PEEK two-way valve connects to a Luer connector and a syringe to evacuate the known volume glass bottle and the front gas path, reducing the residual gas content in the system. A first PEEK two-way valve connects to an external input terminal for the gas to be tested, introducing the gas to be tested into the known volume glass bottle. As the gas to be tested comes into contact with the electrolyte in the known volume glass bottle and gradually establishes gas-liquid equilibrium, a pressure sensor monitors the system pressure changes in real time.

[0022] Furthermore, in the “pull-close-vent-tighten-open” cycle operation, when the syringe is pulled, the gas in the glass bottle of known volume enters the syringe; after closing the second PEEK two-way valve, the Luer connector is loosened to discharge the gas in the syringe to the atmosphere; repeating the operation achieves efficient evacuation of the micro-cavity.

[0023] Compared with the prior art, the beneficial effects of the present invention include: (i) Simple structure and easy operation: Manual vacuuming is achieved by combining a syringe with a Luer connector, without the need for an external vacuum pump, making it suitable for rapid laboratory testing and teaching demonstrations.

[0024] (ii) Independent control and precise testing: The air intake and extraction processes are controlled by the first PEEK two-way valve and the second PEEK two-way valve respectively, so as to achieve independent control and precise operation of the testing process.

[0025] (iii) Good sealing performance and airtight self-test: The balance pressure is greater than atmospheric pressure, which can be used as an intuitive basis for judging the airtightness of the system and effectively avoid measurement errors caused by leakage.

[0026] (iv) Strong corrosion resistance: PEEK pipes and PEEK fittings are used in all connection parts, which have excellent resistance to electrolyte corrosion and are suitable for long-term stable testing.

[0027] (v) High scalability: It can be used in conjunction with an electrochemical workstation to achieve simultaneous characterization of pressure changes and electrochemical processes. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the gas path connection of the present invention; Figure 2 This is an overall framework diagram of the present invention; Figure 3 For a complete pressure curve, P2 > atmospheric pressure; Figure 4 For the leakage pressure curve, P2 = atmospheric pressure; Figure 5 Schematic diagrams of the shape and structure of the first and second PEEK two-way valves; Figure 6 This is a schematic diagram of the pressure sensor structure; Figure 7 This is a schematic diagram of a syringe structure; Figure 8 This is a schematic diagram of a PEEK connector structure.

[0029] Among them, 1. External gas input terminal, 2. First PEEK two-way valve, 3. Pressure sensor, 4. Glass bottle inlet, 5. Glass bottle of known volume, 6. Glass bottle outlet, 7. Second PEEK two-way valve, 8. Luer connector, 9. Syringe. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1 like Figures 1 to 2 As shown in the embodiment of the present invention, a closed-loop testing device for determining the gas dissolution behavior in an electrolyte includes: an external gas input terminal 1, a first PEEK two-way valve 2, a pressure sensor 3, a glass bottle inlet 4, a glass bottle of known volume 5, a glass bottle outlet 6, a second PEEK two-way valve 7, a Luer connector 8, and a syringe 9. All components are connected in series via PEEK tubing to form a complete closed-loop testing system.

[0032] The known volume glass bottle 5 is a transparent cylindrical glass bottle used to hold the electrolyte to be tested, forming a closed gas phase space above the liquid surface. A sealing cap is installed on the top of the known volume glass bottle 5, and the sealing cap has a glass bottle inlet 4 and a glass bottle outlet 6, which are used to realize gas introduction and gas export, respectively.

[0033] Along the gas path, the device is as follows: external gas input terminal 1 → first PEEK two-way valve 2 → pressure sensor 3 → glass bottle inlet 4 → glass bottle of known volume 5 → glass bottle outlet 6 → second PEEK two-way valve 7 → Luer connector 8 → syringe 9.

[0034] Specifically, after the external gas to be tested enters through the external gas input terminal 1, it first passes through the first PEEK two-way valve 2 for on / off control, and then enters the pressure sensor 3 through the PEEK pipeline. The pressure sensor 3 is connected to the glass bottle inlet 4 at the top of the glass bottle 5 of known volume through the PEEK pipeline, allowing the gas to be tested to enter the glass bottle 5 of known volume, come into contact with the electrolyte inside the bottle, and form a gas-liquid balance.

[0035] A glass bottle 5 has a vent 6 on its top side, which is connected to a second PEEK two-way valve 7 via a PEEK tubing. The rear end of the second PEEK two-way valve 7 is connected to a Luer connector 8 and a syringe 9. The Luer connector 8 is a screw-on connection structure used for detachable connection with the syringe 9, ensuring a tight seal at the connection point. The syringe 9 allows for evacuation of the entire test system to reduce residual gas content and establish a low-pressure environment.

[0036] In this embodiment, all gas connection pipes are made of PEEK material, and all connection parts are sealed with PEEK connectors, thereby improving the corrosion resistance, sealing and stability of the device.

[0037] Both the first PEEK two-way valve 2 and the second PEEK two-way valve 7 have a block-shaped valve body structure. Each valve body has a connection port at both ends, and a toggle valve handle at the top for controlling the opening and closing of the air passage. The structures of the first PEEK two-way valve 2 and the second PEEK two-way valve 7 are as follows: Figure 5 As shown.

[0038] Pressure sensor 3 is a cylindrical pressure sensor with a slender cylindrical metal housing as its main body. It has connectors at both ends and is connected to the front and rear PEEK pipelines through the connectors.

[0039] The glass bottle 5 is a transparent cylindrical glass bottle with a disc-shaped sealing cap on top. The sealing cap has two vertically upward-pointing connectors, which serve as the air inlet 4 and the air outlet 6 of the glass bottle, respectively. The lower part of each connector is a short and thick cylindrical base, which extends upward into a slender cylindrical connecting section, and the upper part is equipped with a screw-on locking cap.

[0040] The Luer connector 8 is a screw-on connection structure. It is a multi-step cylindrical shape. One end is connected to the second PEEK two-way valve 7, and the other end is detachably connected to the syringe 9. It has a threaded locking part on the outer periphery.

[0041] The syringe 9 has a standard syringe structure, consisting of a transparent cylindrical syringe 9 and an internal piston rod. The front end of the syringe 9 has a tapered connecting nozzle that fits tightly with the Luer connector 8. The structure of the syringe 9 is as follows... Figure 7 As shown.

[0042] All gas connection pipes are made of PEEK material, appearing as slender, flexible round tubes with a light yellow color. All connections are sealed with PEEK connectors, which are short cylindrical fittings with a multi-stepped cylindrical structure and locking grooves on the surface. Figure 8 As shown.

[0043] Multi-layer sealing structure: All gas connection pipes are made of PEEK material. From the gas cylinder to the inlet, from the inlet to the first PEEK two-way valve, from the first PEEK two-way valve to the pressure sensor, from the pressure sensor to the glass bottle inlet, from the glass bottle outlet to the second PEEK two-way valve, and from the second PEEK two-way valve to the Luer connector, all these connections are made of PEEK material. All gas connection points are sealed with PEEK connectors, which have excellent corrosion resistance and sealing performance.

[0044] The working principle is as follows: This invention is based on the ideal gas law PV=nRT, which states that under constant temperature T and gas phase volume V, the amount of gaseous substance n is directly proportional to the pressure P. The amount of dissolved gas can be calculated by measuring the pressure difference ΔP before and after gas dissolution.

[0045] By connecting the second PEEK two-way valve 7 to the Luer connector 8 and the syringe 9, the known volume glass bottle 5 and the front gas path can be evacuated to reduce the residual gas content in the system. By connecting the first PEEK two-way valve 2 to the external gas input terminal 1, the gas to be tested can be introduced into the known volume glass bottle 5. When the gas to be tested comes into contact with the electrolyte in the known volume glass bottle 5 and gradually establishes gas-liquid equilibrium, the pressure sensor 3 monitors the system pressure change in real time, thus providing a device basis for the analysis of gas dissolution behavior in the electrolyte.

[0046] The combination of syringe 9 and Luer connector 8 enables manual repeated vacuuming: when syringe 9 is pulled, gas in glass bottle 5 of known volume enters syringe; after closing the second PEEK two-way valve 7 and loosening Luer connector 8, the gas in syringe can be discharged to the atmosphere; repeated operation can achieve efficient evacuation of the micro-cavity.

[0047] Example 2 The testing methods and data processing are as follows: In this embodiment, a 12 mL glass bottle (5) of known volume was used, and 6 mL of 1M LiPF6 EC / EMC (3:7) electrolyte was added. The test gas was CO2. The test environment temperature was 25℃ (298 K), and the local atmospheric pressure was 0.1 MPa.

[0048] The testing process is as follows: (1) System evacuation: Close the first PEEK two-way valve 2, open the second PEEK two-way valve 7, pull the syringe 9 to its maximum stroke, perform the first evacuation of the glass bottle 5 with a known volume, then close the second PEEK two-way valve 7, loosen the Luer connector 8 to release the gas in the syringe 9, then tighten the Luer connector 8 and open the second PEEK two-way valve 7, repeat the above operation 5 times. At this time, the pressure sensor 3 shows that the absolute pressure is lower than 0.02 MPa, reaching a vacuum state, and close the second PEEK two-way valve 7.

[0049] (2) Instantaneous air intake: Quickly open the first PEEK two-way valve 2 to allow CO2 to be instantly injected into the glass bottle 5 of known volume, and then immediately close the first PEEK two-way valve 2. Record the reading of the pressure sensor 3 at this time as P1 = 0.1137 MPa (absolute pressure).

[0050] (3) Equilibrium determination: The device was placed in a constant temperature environment of 25℃ and the gas and electrolyte were allowed to reach gas-liquid equilibrium. The pressure gradually decreased over time, and after 2 hours the pressure stabilized at P2 = 0.1120 MPa (absolute pressure). This value is greater than the local atmospheric pressure (0.1 MPa), indicating that the system has good airtightness and the gas dissolution has reached equilibrium.

[0051] (4) Data processing: Given the volume of the gas chamber inside the glass bottle 5, V = total volume - electrolyte volume = 12 mL - 6 mL = 6 mL = 6.0 × 10 -6 m 3 The temperature is T = 298 K, and the gas constant is R = 8.314 J / (mol·K). Calculate the amount of CO2 dissolved into the electrolyte using the ideal gas law PV = nRT: Δn = (P1-P2)×V / (R×T); Substitute the data: P1-P2= 0.1137 MPa-0.1120 MPa = 0.0017 MPa = 1700 Pa V = 6.0 × 10 -6 m 3 R = 8.314 J / (mol·K) T = 298 K Δn = (1700 × 6.0 × 10 -6 ) / (8.314×298) Δn = 0.0102 / 2477.572 Δn = 4.12 × 10 -6 mol Solubility S = Δn / electrolyte volume = 4.12 × 10 -6 mol / 0.006 L = 6.87 × 10 -4 mol / L= 0.687 mmol / L (i.e. 0.687 μmol / mL).

[0052] Comparative Example 1 To verify the airtightness self-test function of this invention, a slight leak was intentionally left during the assembly of the device in this comparative example. The operating steps of Example 1 were repeated, and the equilibrium pressure was observed to continuously decrease, eventually falling below atmospheric pressure (0.1 MPa), indicating a leak in the system and rendering the measurement data invalid. This comparison demonstrates that the equilibrium pressure greater than atmospheric pressure, as described in this invention, can serve as an effective criterion for judging the airtightness of the system.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A closed testing device for determining the gas dissolution behavior in an electrolyte, characterized in that, include: Intake control module: Configures an external gas input terminal (1) and a first PEEK two-way valve (2) to realize the on / off control of the gas to be tested; Pressure monitoring module: A cylindrical pressure sensor (3) is used, which is connected to the air intake control module and the test container through a PEEK pipeline to monitor the pressure changes of the system in real time; Test container module: A glass bottle of known volume (5) is used, with a sealing cap on the top. The sealing cap has a glass bottle inlet (4) and a glass bottle outlet (6) for holding electrolyte and providing a closed gas phase space; Vacuum control module: includes a second PEEK two-way valve (7), a Luer connector (8) and a syringe (9), which realizes the system vacuum by manually pulling the syringe; The external gas input terminal (1), the first PEEK two-way valve (2), the pressure sensor (3), the glass bottle inlet (4), the glass bottle of known volume (5), the glass bottle outlet (6), the second PEEK two-way valve (7), the Luer connector (8), and the syringe (9) are connected in series through PEEK pipelines to form a complete closed test system.

2. The sealed testing device for determining the gas dissolution behavior in an electrolyte according to claim 1, characterized in that, The first PEEK two-way valve (2) is connected to the external gas input terminal (1), the pressure sensor (3) is connected to the first PEEK two-way valve (2) through a PEEK pipeline, the known volume glass bottle (5) is connected to the pressure sensor (3) through a PEEK pipeline, the glass bottle inlet (4) at the top of the known volume glass bottle (5) is connected to the pressure sensor (3), the second PEEK two-way valve (7) is connected to the glass bottle outlet (6) through a PEEK pipeline, the Luer connector (8) is connected to the rear end of the second PEEK two-way valve (7), and the syringe (9) is detachably connected to the Luer connector (8).

3. The sealed testing device for determining the gas dissolution behavior in an electrolyte according to claim 1, characterized in that, The known volume glass bottle (5) is a transparent cylindrical glass bottle body, the sealing cap is a disc-shaped sealing cap, and the glass bottle air inlet (4) and the glass bottle air outlet (6) are both located on the sealing cap.

4. The sealed testing device for determining the gas dissolution behavior in an electrolyte according to claim 1, characterized in that, Both the first PEEK two-way valve (2) and the second PEEK two-way valve (7) have a block-shaped valve body structure, and the top of the valve body is provided with a toggle valve handle.

5. The sealed testing device for determining the gas dissolution behavior in an electrolyte according to claim 1, characterized in that, The Luer connector (8) is a screw-on connection structure.

6. The sealed testing device for determining the gas dissolution behavior in an electrolyte according to claim 1, characterized in that, All gas connection pipes are made of PEEK material, and all connections are sealed with PEEK fittings.

7. The closed testing device for determining the gas dissolution behavior in an electrolyte according to claim 1, characterized in that, The pressure sensor (3) is also connected to the electrochemical workstation for synchronous monitoring of pressure and electrochemical signals during the test process.

8. The closed testing device for determining the gas dissolution behavior in an electrolyte according to claim 1, characterized in that, After the syringe (9) is connected to the Luer connector (8), it is used to perform air extraction on the entire test system.

9. A manual vacuuming method for a closed testing device used to determine the gas dissolution behavior in an electrolyte, characterized in that, By connecting the Luer connector (8) and the syringe (9) through the second PEEK two-way valve (7) in any one of claims 1-8, the device can repeatedly pump air from a glass bottle (5) of known volume and the front gas path until a vacuum state is reached by adopting the cyclic operation of "pull-close-vent-tighten-open".

10. A self-testing method for the airtightness of a closed testing device for determining the gas dissolution behavior in an electrolyte, characterized in that, Using the apparatus described in any one of claims 1-8, after the gas to be tested is instantaneously introduced, the pressure change is monitored; when the equilibrium pressure P2 is stable and greater than atmospheric pressure, it indicates that the system has good airtightness and the gas dissolution has reached equilibrium.

Images