An in-situ optical-raman-mass spectrometry combined characterization system and method

Abstract

The application discloses an in-situ optical-Raman-mass spectrum combined characterization system and method, and belongs to the technical field of in-situ characterization. The system mainly comprises a gas inlet unit, an in-situ electrochemical reaction cell (in-situ cell) and a gas outlet unit. In the in-situ cell device, from top to bottom, there are an optical window, an electrode one, a diaphragm rich in electrolyte, an electrode two and a gas inlet and outlet pipeline. According to different test purposes, the positions of the working electrode and the counter electrode (reference electrode) can be flexibly exchanged, and the working electrode can be close to the optical window or away from the optical window. The device is in a closed environment, can be tested under atmosphere control conditions, and can collect and analyze products in time. The application can realize in-situ optical microscope imaging, Raman and mass spectrum characterization, can simultaneously capture electrochemical signals-optical microscope imaging signals, electrochemical signals-Raman signals and electrochemical signals-mass spectrum signals, and has potential application value in the fields of energy and catalysis.

Description

Technical Field

[0001] This invention relates to an in-situ optical-Raman-mass spectrometry characterization system and method, belonging to the field of in-situ characterization technology. Background Technology

[0002] In-situ characterization techniques can link reaction conditions with electrode changes, thus revealing more clearly the relationship between electrode structure, composition, and activity under operating conditions. In-situ electrochemical optical microscopy imaging can directly present information such as structural and color changes during electrode charging and discharging; in-situ electrochemical Raman spectroscopy can reflect information such as molecular vibration and rotation in the sample being tested, used for molecular structure research and analysis; in-situ electrochemical mass spectrometry can dynamically analyze volatile products and intermediates generated in the reaction. To obtain more complete and comprehensive information, combining in-situ optical microscopy imaging, in-situ Raman spectroscopy, and in-situ mass spectrometry to deduce electrochemical reaction mechanisms is a foreseeable and ideal method. However, due to various technical obstacles, there are currently no studies, domestically or internationally, that combine these three techniques and use in-situ optical microscopy imaging, in-situ Raman spectroscopy, and in-situ mass spectrometry on the same electrode in the same in-situ cell. Therefore, given the current situation, there is an urgent need to design an in-situ cell device that can be used for optical microscopy imaging, Raman spectroscopy, and mass spectrometry testing. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides an in-situ optical-Raman-mass spectrometry characterization system and method. The characterization system uses in-situ optical microscopy imaging, in-situ Raman spectroscopy, and in-situ mass spectrometry on the same electrode in the same in-situ cell, which has potential application value in energy, catalysis and other fields.

[0004] The first aspect of this invention protects an in-situ optical-Raman-mass spectrometry (OAS) characterization system, comprising an in-situ electrochemical cell, the in-situ electrochemical cell including an externally threaded tee with ends a, b, and c, the ends a and b respectively connected to an inlet unit and an outlet unit, and the ends c having, in the axial direction from the outside to the inside, an observation window, an electrode a, a diaphragm, and an electrode b; the characterization system includes wires a and b, one end of wire a connected to the electrode a, and the other end of wire a disposed outside the characterization system; one end of wire b connected to the electrode b, and the other end of wire b disposed outside the characterization system; the inner side of the observation window is a sealed environment.

[0005] Furthermore, the materials of wires a and b include metal.

[0006] Furthermore, internal threaded connectors are provided on the outer sides of the a, b, and c ends, and ferrules are provided between the internal threaded connectors and the a, b, and c ends; both wire a and wire b are embedded in the internal threaded connector of the c end.

[0007] Furthermore, the diaphragm comprises a glass fiber membrane or a polymer film, which is wetted with an electrolyte before use. The polymer film includes a polyethylene film.

[0008] Furthermore, end a is provided with a coarse air intake pipe, one end of which is connected to the air intake unit, and the other end of which is connected to one end of a fine air intake pipe via adapter pipe a. The other end of the fine air intake pipe is located below the electrode b. End b is provided with a coarse air outlet pipe, one end of which is connected to the air outlet unit, and the other end of which is connected to one end of the fine air outlet pipe via adapter pipe b. The other end of the fine air outlet pipe is located below the electrode b, 1-2 mm below the port of the fine air intake pipe.

[0009] Furthermore, the space between the inlet capillary tube, the outlet capillary tube, and the external threaded tee is filled with sealing material, so that the space between the electrode b and the inlet capillary tube and the outlet capillary tube is 20-60 μL.

[0010] Furthermore, the diameters of both the intake manifold and the exhaust manifold are 3-10 mm, preferably 6 mm.

[0011] The diameters of both the adapter tube a and the adapter tube b are 3-6 mm, preferably 3 mm.

[0012] The diameters of the inlet capillary tube and the outlet capillary tube are both 1-2 mm; the inlet capillary tube and the outlet capillary tube are respectively inserted into one end of the adapter tube a and the adapter tube b, and the other ends of the adapter tube a and the adapter tube b are respectively inserted into the inlet capillary tube and the outlet capillary tube; the connection between different tube diameters is sealed with polytetrafluoroethylene tape.

[0013] Furthermore, the material of the external threaded tee includes polytetrafluoroethylene or polyetheretherketone, and the material of the observation window includes quartz.

[0014] The second aspect of this invention protects a characterization method for an in-situ optical-Raman-mass spectrometry characterization system, comprising the following steps:

[0015] Place the observation window, electrode a, and diaphragm sequentially into the internal threaded connector at end c; wet the diaphragm with electrolyte, the amount of electrolyte being 100μL-140μL; then place the electrode b, and then slowly screw the external threaded tee c into the internal threaded connector to press the electrode, diaphragm, wire, and observation window together;

[0016] Enable optical microscopy imaging, Raman measurement, or in-situ mass spectrometry characterization, and perform cyclic voltammetry testing at a scan rate of 0.2 mV / s. -1 -0.6mV s-1 The scanning range is 0V-3V.

[0017] Furthermore, the electrolyte is a LiPF6 EC / DMC / EMC = 1 / 1 / 1 wt.% solution, and the concentration of LiPF6 in the electrolyte is 1-5M.

[0018] Furthermore, the optical microscope or Raman spectrometer probe is located above and outside the observation window of the characterization system; the mass spectrometer is connected to the gas exhaust unit.

[0019] Beneficial effects:

[0020] (1) The characterization system described in this invention can be modified based on the Swagelok tee connector (Swagelok cell) commonly used in gas path construction, without the need to remake the reaction cell separately, and the assembly and replacement of each component are convenient.

[0021] (2) The characterization system described in this invention does not require additional fastening screws and sealing rings, and the material is made of polytetrafluoroethylene or polyether ether ketone, which has strong chemical stability and avoids pollution that may be caused by the introduction of other materials.

[0022] (3) In the characterization system described in this invention, two wires are embedded in the sidewall of the internal threaded connector and can rotate together with the connector during assembly. In the electrolytic cell, the exposed portions of the wires are connected to the two electrodes respectively, thus not affecting the airtightness of the Swagelok connector itself.

[0023] (4) The characterization system described in this invention does not require specially made porous films and porous metal support sheets. Instead, it uses a gas inflow-outflow method to transfer almost all products to a mass spectrometer for analysis.

[0024] (5) The inlet and outlet gas paths of the characterization system described in this invention are very close to electrode b, so that the products generated by the reaction can be quickly pushed out of the reaction cell and transferred to the mass spectrometer for detection, which has a rapid response capability and is easy to correlate with the applied electrochemical conditions.

[0025] (6) The gas generated at the working electrode can overflow from the edge of the electrode and enter the cavity below electrode b, where it is collected by the gas outlet capillary and further transported to the mass spectrometer. Therefore, the working electrode does not necessarily have to be an electrode with a porous structure.

[0026] (7) The characterization system described in this invention uses a pre-wetted diaphragm, thereby greatly reducing the use of electrolytes, especially organic solvents, ionic liquids and the like.

[0027] (8) The characterization system of the present invention adopts an electrode stacking method, and gradually assembles the battery parts together by applying a certain pressure during rotation. The structure is small and compact, and can simulate actual devices such as button batteries. While achieving similar electrochemical performance, it can better reflect the real state in actual batteries and perform in-situ characterization.

[0028] (9) In the characterization system described in this invention, electrode a is close to the observation window, which facilitates in-situ optical characterization and in-situ Raman characterization.

[0029] (10) The two-electrode system (electrode a and electrode b) of the characterization system described in this invention is very close to each other and is separated only by a diaphragm (to avoid short circuits). It can be extended into a three-electrode system as needed.

[0030] (11) Depending on the testing objective, the positions of the working electrode and the counter electrode (reference electrode) can be flexibly interchanged. The working electrode can be placed near or away from the optical window. This device operates in a sealed environment, allowing for testing under controlled atmosphere conditions and timely collection and analysis of products. The characterization system in this invention utilizes in-situ optical microscopy imaging, in-situ Raman spectroscopy, and in-situ mass spectrometry on the same electrode in the same in-situ cell. It can simultaneously capture electrochemical signals-optical microscopy imaging signals, electrochemical signals-Raman signals, and electrochemical signals-mass spectrometry signals, demonstrating potential applications in energy, catalysis, and other fields. Attached Figure Description

[0031] Figure 1 This is a diagram showing the components of the characterization system described in this invention.

[0032] Figure 2 This is a cross-sectional view of the in-situ electrochemical cell of the characterization system described in this invention.

[0033] In the diagram, 1. External thread tee; 2. Internal thread connector; 3. Compression fitting; 4. Observation window; 5. Electrode a; 6. Diaphragm; 7. Electrode b; 8. Wire a; 9. Wire b; 10. Inlet pipe; 11. Adapter pipe a; 12. Inlet pipe; 13. Outlet pipe; 14. Outlet pipe; 15. Sealing material; 16. Adapter pipe b.

[0034] Figure 3 The images shown are the cyclic voltammogram (a) and the corresponding optical photograph (b) of the electrode surface, which are characterized by in-situ optical microscopy imaging in Embodiment 1 of the present invention.

[0035] Figure 4 The images shown are the cyclic voltammogram (a), the corresponding spectroscopic image (b), and the curve (c) of the in-situ Raman test in Embodiment 2 of the present invention.

[0036] Figure 5This is a graph showing the correspondence between the voltage (a), current (b), and hydrogen (c) mass spectrometry signals during online mass spectrometry testing in Embodiment 3 of the present invention. Detailed Implementation

[0037] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way.

[0038] Example 1

[0039] like Figure 1-2As shown, an in-situ optical-Raman-mass spectrometry (OIS) characterization system includes an in-situ electrochemical cell. The in-situ electrochemical cell includes an externally threaded tee 1, which has ends a, b, and c. Ends a and b are respectively connected to an inlet unit and an outlet unit. The axial direction of end c is provided with an observation window 4, an electrode a 5, a diaphragm 6, and an electrode b 7 arranged sequentially from the outside to the inside. The characterization system includes a wire a 8 and a wire b 9. One end of wire a 8 is connected to the electrode a 5, and the other end of wire a 8 is located outside the characterization system. One end of wire b 9 is connected to the electrode b 7, and the other end of wire b 9 is located outside the characterization system. The inside of the observation window 4 is a sealed environment. An internal threaded connector 2 is provided on the outer side of each of the three ends, namely end a, end b, and end c. A retaining sleeve 3 is provided between the internal threaded connector 2 and the three ends, respectively. Both wire a 8 and wire b 9 are embedded in the internal threaded connector 2 at end c. The diaphragm 6 is a glass fiber membrane or a polymer film, which is moistened with electrolyte before use. The a-end is provided with an air inlet pipe 10, one end of which is connected to the air intake unit. The other end of the air inlet pipe 10 is connected to one end of an air inlet pipe 12 via an adapter pipe a11. The other end of the air inlet pipe 12 is located below the electrode b7. The b-end is provided with an air outlet pipe 14, one end of which is connected to the air outlet unit. The other end of the air outlet pipe 14 is connected to one end of an air outlet pipe 13 via an adapter pipe b16. The other end of the air outlet pipe 13 is located below the electrode b7, 1-2 mm below the port of the air inlet pipe 12. A sealing material 15 is filled between the air inlet pipe 12 and the air outlet pipe 13 and the external threaded tee 1, so that the space between the electrode b7 and the air inlet pipe 12 and the air outlet pipe 13 is 20-60 μL. The diameters of the inlet pipe 10 and the outlet pipe 14 are both 3-10 mm, the diameters of the adapter pipe a 11 and the adapter pipe b 16 are both 3-6 mm, and the diameters of the inlet pipe 12 and the outlet pipe 13 are both 1-2 mm. The inlet pipe 12 and the outlet pipe 13 are respectively inserted into one end of the adapter pipe a 11 and the adapter pipe b 16, and the other ends of the adapter pipe a 11 and the adapter pipe b 16 are respectively inserted into the inlet pipe 10 and the outlet pipe 14. The connections between pipes of different diameters are sealed with polytetrafluoroethylene tape. The material of the external threaded tee 1 is polytetrafluoroethylene or polyetheretherketone; the material of the observation window 4 is quartz.

[0040] Example 2

[0041] The in-situ cell described in Example 1 can be used to simultaneously characterize electrochemical signals and optical microscope imaging signals. The specific method is as follows:

[0042] To study the macroscopic structural and color changes of graphite electrodes during lithium-ion battery operation, in-situ optical microscopy was used for characterization. The observation window, electrode a, and separator were sequentially placed into the internally threaded connector at end c of the characterization system. The separator was moistened with electrolyte, and then electrode b was placed in. The externally threaded tee (end c) was then slowly screwed into the internally threaded connector, pressing the electrode, separator, and wires firmly against the observation window. The in-situ optical microscope probe was placed directly above and outside the observation window of the characterization system. The electrolyte used was 1M LiPF6 in EC / DMC / EMC = 1 / 1 / 1 wt.%, with a volume of 120 μL. Electrode a was the graphite working electrode, and electrode b was a lithium metal sheet serving as the counter electrode. Cyclic voltammetry was performed simultaneously with optical microscopy imaging at a scan rate of 0.3 mV / s and a scan range of 3V-0V. Optical microscopy images of lithium-ion intercalation / deintercalation at different potentials are shown below. Figure 3 As shown. Figure 3 As can be seen, during discharge, lithium ions intercalate into the graphite electrode, causing structural changes and resulting in different colors at different potentials. During the subsequent charging process, lithium ions deintercalate, causing the electrode surface color to change inversely relative to the discharge process, but it does not completely return to its initial state.

[0043] Example 3

[0044] The in-situ cell described in Example 1 can be used to simultaneously characterize electrochemical signals and Raman signals. The specific method is as follows:

[0045] To study the microscopic molecular structure changes during lithium-ion battery operation, specifically the intercalation / deintercalation of lithium ions in graphite electrodes, an in-situ Raman characterization method was used. The observation window, electrode a, and separator were sequentially placed into the internally threaded connector at end c of the characterization system. The separator was then moistened with electrolyte, followed by the electrode b. Finally, the externally threaded tee (end c) was slowly screwed into the internally threaded connector, pressing the electrode, separator, and wires firmly against the observation window. The Raman spectrometer probe was positioned directly above and outside the observation window of the characterization system. The electrolyte used was 1M LiPF6 in EC / DMC / EMC = 1 / 1 / 1 wt.%, with a volume of 120 μL. Electrode a was the graphite working electrode, and electrode b was a lithium metal sheet serving as the counter electrode. Cyclic voltammetry was performed simultaneously with Raman measurement at a scan rate of 0.3 mV / s. -1 The scanning range is 3V-0V. The Raman spectra of lithium ion intercalation / deintercalation in the graphite electrode at different potentials are shown below. Figure 4 As shown. Figure 4 As can be seen, when the battery discharges to approximately 0.45V, the G peak of the graphite electrode (~1581 cm⁻¹) is observed. -1(representing the uncharged state) gradually moves to a higher wave number and splits into two peaks (~1575cm). -1 and ~1603cm -1 (This represents the charging state). When the battery discharges to approximately 0.1V, the G peak completely disappears, indicating that lithium ions have been intercalated into the various graphite layers. During battery charging, the graphite G peak reversibly returns to ~1581cm⁻¹. -1 This indicates that the intercalation and deintercalation behavior of lithium ions in the graphite electrode is reversible.

[0046] Example 4

[0047] The in-situ cell described in Example 1 can be used to simultaneously characterize electrochemical signals and mass spectrometry signals. The specific method is as follows:

[0048] In-situ mass spectrometry was used to characterize the volatile products and intermediates generated during the electrochemical reaction between graphite electrodes and electrolytes in lithium-ion batteries. The observation window, electrode a, and diaphragm were sequentially placed into the internally threaded connector at end c of the characterization system. The diaphragm was moistened with electrolyte, and then electrode b was placed in. The externally threaded tee (end c) was then slowly screwed into the internally threaded connector to press the electrode, diaphragm, and lead wires tightly against the observation window. The mass spectrometer's sample inlet capillary was connected to the gas outlet tube of the gas outlet unit. The electrolyte used was 1M LiPF6 in EC / DMC / EMC = 1 / 1 / 1 wt.%, with a volume of 120 μL. Electrode a was a lithium metal sheet, serving as the counter electrode, and electrode b was the graphite working electrode. After the mass spectrometer started scanning and the blank baseline stabilized, an electrochemical potential scan was performed at a scan rate of 0.5 mV / s. -1 The scanning range is 3V-0V. Products are collected through the mass spectrometer inlet and their mass spectrometric signals are analyzed. Figure 5 As shown.

[0049] Example 5

[0050] The characterization system described in this invention can simultaneously characterize at least one of the following: electrochemical signal-optical microscope imaging signal, electrochemical signal-Raman signal, and electrochemical signal-mass spectrometry signal. This can be achieved by placing the in-situ optical microscope probe head directly above the outside of the observation window of the characterization system, placing the Raman spectrometer probe head directly above the outside of the observation window of the characterization system, or connecting the mass spectrometer injection capillary to the gas outlet tube of the gas outlet unit.

Claims

1. An in-situ optical-Raman-mass spectrometry hyphenated characterization system, characterized by, The system includes an in-situ electrochemical cell, which includes an external threaded tee (1) with end a, end b, and end c. End a and end b are connected to an inlet unit and an outlet unit, respectively. End c has an observation window (4), an electrode a (5), a diaphragm (6), and an electrode b (7) arranged sequentially from the outside to the inside in the axial direction. The characterization system includes a wire a (8) and a wire b (9). One end of wire a (8) is connected to the electrode a (5), and the other end of wire a (8) is located outside the characterization system. One end of wire b (9) is connected to the electrode b (7), and the other end of wire b (9) is located outside the characterization system. The inside of the observation window (4) is a sealed environment. The a-end is provided with an air intake coarse pipe (10), one end of which is connected to the air intake unit, and the other end of which is connected to one end of the air intake fine pipe (12) through the adapter pipe a (11). The other end of the air intake fine pipe (12) is located below the electrode b (7). The b-end is provided with an air outlet coarse pipe (14), one end of which is connected to the air outlet unit, and the other end of which is connected to one end of the air outlet fine pipe (13) through the adapter pipe b (16). The other end of the air outlet fine pipe (13) is located below the electrode b (7), 1-2 mm below the position of the air intake fine pipe (12) port.

2. The in-situ optical-Raman-mass spectrometry characterization system according to claim 1, characterized in that, An internal threaded connector (2) is provided on the outer side of the a end, the b end and the c end, and a ferrule (3) is provided between the internal threaded connector (2) and the a end, the b end and the c end; the wire a (8) and the wire b (9) are both embedded in the internal threaded connector (2) of the c end.

3. The in-situ optical-Raman-mass spectrometry characterization system according to claim 1, characterized in that, The diaphragm (6) includes a glass fiber membrane or a polymer film.

4. The in-situ optical-Raman-mass spectrometry characterization system according to claim 1, characterized in that, The air inlet capillary tube (12) and the air outlet capillary tube (13) are filled with sealing material (15) between them and the external threaded tee (1), so that the space between the electrode b (7) and the air inlet capillary tube (12) and the air outlet capillary tube (13) is 20-60 µL.

5. The in-situ optical-Raman-mass spectrometry characterization system according to claim 1, characterized in that, The diameters of the inlet pipe (10) and the outlet pipe (14) are both 3-10 mm, the diameters of the adapter pipe a (11) and the adapter pipe b (16) are both 3-6 mm, and the diameters of the inlet pipe (12) and the outlet pipe (13) are both 1-2 mm. The inlet pipe (12) and the outlet pipe (13) are respectively inserted into one end of the adapter pipe a (11) and the adapter pipe b (16), and the other end of the adapter pipe a (11) and the adapter pipe b (16) are respectively inserted into the inlet pipe (10) and the outlet pipe (14). The connection between different pipe diameters is sealed with polytetrafluoroethylene tape.

6. The in-situ optical-Raman-mass spectrometry characterization system according to claim 1, characterized in that, The material of the external thread tee (1) includes polytetrafluoroethylene or polyetheretherketone; the material of the observation window (4) includes quartz.

7. A characterization method for a characterization system as described in any one of claims 1-6, characterized in that, Includes the following steps: Place the observation window (4), electrode a (5), and diaphragm (6) into the internal threaded connector (2) at end c in sequence; wet the diaphragm (6) with electrolyte, the amount of electrolyte being 100 μL-140 μL; then place the electrode b (7), and then slowly screw the end c of the external threaded tee (1) into the internal threaded connector (2) to press the electrode, diaphragm, wire, and observation window (4) together; Turn on optical microscope imaging, turn on Raman measurement or turn on in-situ mass spectrometry characterization, perform cyclic voltammetry test, scan rate is 0.2 mV s -1 -0.6 mV s -1 , scan range is 0 V-3 V.

8. The characterization method according to claim 7, characterized in that, The electrolyte is a LiPF6 solution with EC / DMC / EMC = 1 / 1 / 1 wt.%, and the concentration of LiPF6 in the electrolyte is 1-5 M.

9. The characterization method according to claim 7, characterized in that, The optical microscope or Raman spectrometer probe is located above and outside the observation window (4) of the characterization system; the mass spectrometer is connected to the gas outlet unit.

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