Quasi-in-situ conjoint analysis method for battery material

Abstract

The invention discloses a battery material quasi-in-situ conjoint analysis method, which comprises a synchronous thermal analyzer STA and a gas chromatograph-mass spectrometer GCMS, the synchronous thermal analyzer STA is used for analyzing the thermogravimetric value, the temperature and the enthalpy value of a battery material, the synchronous thermal analyzer STA is used for heating a mg-grade battery material sample at a constant rate in an inert gas environment, and the gas chromatograph-mass spectrometer GCMS is used for analyzing the temperature and the enthalpy value of the battery material. Detection is carried out through changes of heat flow and weight, and a change curve of the weight, the temperature and the enthalpy value of the battery material along with time can be obtained; the gas chromatograph-mass spectrometer GCMS is used for analyzing a decomposed material product, a gas product thermally decomposed from the synchronous thermal analyzer STA enters the gas chromatograph-mass spectrometer GCMS through a high-temperature connecting pipe, the gas chromatograph-mass spectrometer GCMS provides programmed heating for the gas product, and gas is subjected to component analysis during heating; the synchronous thermal analyzer STA and the gas chromatograph-mass spectrometer GCMS form a combined analysis device; and the combined analysis device is used for detecting quasi-in-situ characterization of the solid electrolyte.

Description

Technical Field

[0001] The present invention relates to the field of battery material detection, and in particular to a quasi-in-situ joint analysis method for battery materials. Background Art

[0002] As a core link in the new energy industry, battery safety has always been a key point and a difficult point. Battery safety, especially thermal safety, is closely related to the material itself and the decomposition products during the temperature rise process. Establishing corresponding analysis methods can provide guidance and guarantee for battery research and development.

[0003] Among them, in situ characterization technology can use different instruments and equipment to perform "online" analysis on a specific reaction process. It is a technology that uses a specific device to continuously and synchronously analyze substances, and ultimately obtains a series of results with time or other related conditions as parameters. It realizes the analysis of changes in the reaction process of substances and has the characteristics of dynamic, real-time and intuitive.

[0004] By using in situ characterization methods, we can observe the chemical reaction process, material structure and morphology in real time, and obtain information such as reaction intermediates, which helps researchers analyze the reaction mechanism and promote the further development of chemistry and materials science.

[0005] However, the existing quasi-in-situ method for battery materials is to use analytical methods such as infrared spectroscopy and nuclear magnetic resonance. The detection is relatively simple, and the testing of battery materials involves quasi-in-situ thermal stability and decomposition product testing. In actual use, it is found that the combination of infrared spectroscopy and nuclear magnetic resonance is difficult to provide more comprehensive data, which affects the stability of the test. Summary of the invention

[0006] The main purpose of the present invention is to propose a quasi-in-situ combined analysis method for battery materials, which aims to achieve quasi-in-situ testing of the thermal stability of battery materials and has the advantages of low cost and easy operation.

[0007] To achieve the above object, the present invention proposes a quasi-in-situ joint analysis method for battery materials, comprising a synchronous thermal analyzer STA and a gas chromatography-mass spectrometer GCMS.

[0008] The synchronous thermal analyzer STA is used to analyze the thermogravimetry, temperature and thermal enthalpy of battery materials. The synchronous thermal analyzer STA heats mg-level battery material samples at a constant rate in an inert gas environment, and detects the changes in heat flow and weight to obtain the curves of the weight, temperature and thermal enthalpy of the battery materials over time;

[0009] The gas chromatograph-mass spectrometer GCMS is used to analyze the decomposed material products. The gas products of thermal decomposition from the synchronous thermal analyzer STA enter the gas chromatograph-mass spectrometer GCMS through a high-temperature connecting tube. The gas chromatograph-mass spectrometer GCMS provides a programmed temperature increase for the gas products, and the gas is subjected to component analysis during the temperature increase.

[0010] The synchronous thermal analyzer STA and the gas chromatography-mass spectrometer GCMS form a joint analysis device;

[0011] The battery material is a solid electrolyte in different states obtained by assembling a battery for charging and discharging, and the combined analysis device is used to detect the quasi-in-situ characterization of the solid electrolyte.

[0012] The solid-state electrolyte is characterized quasi-in-situ by a combined analysis device. Compared with existing analysis methods such as infrared spectroscopy and nuclear magnetic resonance, it has the characteristics of wide analysis range and high precision. It can obtain the mass number of battery material samples and scan a certain characteristic mass number. It is more suitable as an analysis method for products after thermal decomposition. This test method can be used as a test model to accurately obtain data at different stages of battery solid-state electrolytes quasi-in-situ, thereby improving the safety and stability of solid-state batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the thermogravimetric / differential thermal curve of the sample of the present invention. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, top, bottom, inside, outside, vertical, horizontal, longitudinal, counterclockwise, clockwise, circumferential, radial, axial...), then the directional indication is only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0016] In addition, if there are descriptions involving "first" or "second" etc. in the embodiments of the present invention, the descriptions of "first" or "second" etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0017] like Figure 1 As shown, a quasi-in-situ combined analysis method for battery materials includes a synchronous thermal analyzer STA and a gas chromatography-mass spectrometer GCMS.

[0018] The synchronous thermal analyzer STA is used to analyze the thermogravimetry, temperature and thermal enthalpy of battery materials. The synchronous thermal analyzer STA heats mg-level battery material samples at a constant rate in an inert gas environment, and detects the changes in heat flow and weight to obtain the curves of the weight, temperature and thermal enthalpy of the battery materials over time;

[0019] The gas chromatograph-mass spectrometer GCMS is used to analyze the decomposed material products. The gas products of thermal decomposition from the synchronous thermal analyzer STA enter the gas chromatograph-mass spectrometer GCMS through a high-temperature connecting tube. The gas chromatograph-mass spectrometer GCMS provides a programmed temperature increase for the gas products, and the gas is subjected to component analysis during the temperature increase.

[0020] The synchronous thermal analyzer STA and the gas chromatography-mass spectrometer GCMS form a joint analysis device;

[0021] The battery material is a solid electrolyte in different states obtained by assembling a battery for charging and discharging, and the combined analysis device is used to detect the quasi-in-situ characterization of the solid electrolyte.

[0022] The quasi-in-situ characterization of solid electrolytes is carried out through a combined analysis device. Compared with existing analysis methods such as infrared spectroscopy and nuclear magnetic resonance, it has the characteristics of a wide analysis range and high precision. It can obtain the mass number of battery material samples and can also scan a certain characteristic mass number. It is more suitable as an analysis method for products after thermal decomposition.

[0023] Specifically, the air outlet of the synchronous thermal analyzer STA is connected to the air inlet of the high-temperature connecting pipe.

[0024] The gas outlet of the high temperature connecting tube is connected to the sample inlet of a gas chromatograph-mass spectrometer GCMS.

[0025] The analysis steps of the joint detection and analysis device include:

[0026] Step (1) assembling different batteries with different positive and negative electrodes, separators, and electrolytes, and then subjecting the batteries to charge and discharge experiments with different currents, thereby obtaining positive and negative electrodes and separator samples in different states through charging or discharging;

[0027] Step (2) disassembling, cleaning and drying the positive and negative electrodes and the separator samples in different states under the protection of an inert atmosphere to obtain the samples in different states;

[0028] Step (3) transfers the sample to a combined analysis device for testing, thereby achieving quasi-in-situ detection of the sample under different states.

[0029] Specifically, the step (1) comprises:

[0030] Step (1-1) The positive electrode material is prepared to be a positive electrode sheet, and the negative electrode material is prepared to be a negative electrode sheet, and a positive electrode sheet + a separator + a negative electrode sheet are stacked to obtain a battery;

[0031] Step (1-2) connects the battery to a charger and discharger, performs charging and discharging according to different charging and discharging conditions, and locks the state of the solid electrolyte by powering off after the charge is completed, thereby obtaining positive electrode, negative electrode, and separator samples in different states;

[0032] Specifically, the positive and negative electrodes include a plurality of pole pieces with predetermined proportions and predetermined thicknesses.

[0033] Different proportions and thicknesses of pole pieces can be prepared by different processes (thus obtaining different proportions), and the charging and discharging equipment can be a charging and discharging machine or an electrochemical workstation. The present invention is universal for conventional electrochemical systems. It can be used as a reference model for testing, effectively improving the stability of testing and production.

[0034] Specifically, the step (2) comprises:

[0035] (2-1) After the charge and discharge experiment is completed, the battery is removed and disassembled in an inert gas to obtain the positive and negative electrodes and the separator;

[0036] (2-2) The solid electrolyte sheet was cleaned 3-4 times with a cleaning agent dimethyl carbonate solvent (DMC, >99.5%) in an inert gas atmosphere and dried for more than 12 hours to obtain the samples in different states.

[0037] The advantages of adopting the above scheme are: during the whole process, the above samples are only in three environments: inside the battery, in an inert atmosphere, and in a vacuum, which effectively avoids distortion of the test results caused by moisture and oxygen in the air. The use of cleaning agents can effectively avoid distortion of the test results caused by residues of other substances.

[0038] Specifically, the synchronous thermal analyzer STA is a PE synchronous thermal analyzer STA8000 from the United States, and the gas chromatograph-mass spectrometer GCMS is a PE Cl arus590 / SQ8T from the United States.

[0039] Specifically, the step (3) comprises:

[0040] (3-1) Open the sample compartment door of the synchronous thermal analyzer STA, place an empty crucible and reset to zero;

[0041] (3-2) Take out the empty crucible and add a certain amount of sample (solid, liquid, or solid + liquid) about 1-10 mg. If the sample requires an inert atmosphere, it should be operated in a glove box with the door closed;

[0042] (3-3) Weigh the specific mass on the synchronous thermal analyzer STA, adjust the gas flow rate to 50 ml / min, set the equilibration time to 10 min, and set the heating rate to 20 °C / min to 1000 °C (the specific heating rate and final temperature can be changed according to the material properties). After starting the operation, call the gas chromatography-mass spectrometry (GCMS) method parameters within the equilibration time.

[0043] Specifically, the decomposition products of (3-3) can be scanned for all possible substances using Scan mode, or for specific substances using SIM mode.

[0044] The analysis conditions of the synchronous thermal analyzer STA in the test method described in the present invention are changed according to the specific detection requirements, heating temperature: the temperature can be from room temperature to 1000°C, heating rate: 20°C / min; inert gas atmosphere: helium, 50ml / min; sample amount: 1~10mg, the sample amount can be appropriately increased or decreased according to the heat generation of the sample.

[0045] The high temperature connecting pipe condition in the test method of the present invention is: 270°C.

[0046] The gas chromatography-mass spectrometry (GCMS) analysis conditions in the test method of the present invention are as follows:

[0047] Inlet: 260°C, flow rate 1 ml / min, split ratio 10:1, gas saver closed;

[0048] Hollow chromatographic column: 10m*250μm*0μm; Column box: 250℃, maintain 999min;

[0049] Mass spectrometry: solvent delay 2.5 min, ion source temperature 230 °C, quadrupole temperature 150 °C, full scan using Scan mode, characteristic ion scan using SIM mode, mass-to-charge ratios of 10, 16, 18, 28, 30, 32, 42, 44, 48, 86, 88, 104, and 126 ions selected for monitoring.

[0050] The test method of the present invention operates as follows:

[0051] 1. Open the sample compartment door of the synchronous thermal analyzer STA, place an empty crucible and reset to zero;

[0052] 2. Take out the empty crucible and add a certain amount of about 1-10 mg of sample (solid, liquid, or solid + liquid). If the sample requires an inert atmosphere, it should be operated in a glove box with the door closed;

[0053] 3. Weigh the specific mass on the synchronous thermal analyzer STA, adjust the gas flow rate to 50 ml / min, set the equilibrium time to 10 min, and the heating rate to 20 ° C / min to 1000 ° C (the specific heating rate and final temperature can be changed according to the material properties). After starting the operation, call the gas chromatography-mass spectrometry GCMS method parameters within the equilibrium time;

[0054] 4. In SIM mode, you need to enter the characteristic ions you want to collect, such as "2" for hydrogen, "32" for oxygen, etc. Use the single injection mode. When the synchronous thermal analyzer STA is balanced and starts to heat up, click to perform manual injection.

[0055] Result analysis of the test method described in the present invention: Thermogravity, temperature and thermal enthalpy of the material are automatically calculated by the synchronous thermal analyzer STA software, and the characteristic ion mass spectrum of the decomposition product can be selected by the gas chromatography-mass spectrometry GCMS software.

[0056] Figure 1 This is an embodiment of the present invention, which is a thermogravimetric / differential thermal curve of the sample. The other curves correspond to the changes of ions with different mass-to-charge ratios at the mass spectrum end over time.

[0057] It can be seen that, except for m / z=18, the intensity of other ions increases significantly only in the last weight loss stage. It can be seen that the main weight loss of the sample is above 750℃.

[0058] In the figure, the first peak temperature of DSC is 82°C, and the TGA weight loss is 5%. Combined with the result of the chromatographic peak of characteristic ion 18 scanned by gas chromatography-mass spectrometry (GCMS), it indicates that this may be the reason why the sample loses H2O.

[0059] The second peak temperature is 429°C, and the TGA weight loss is 1.0%, which may be due to the slight decomposition of the material. There is no obvious peak in the characteristic ion scanning of the gas chromatography-mass spectrometer GCMS.

[0060] The result of the appearance of chromatographic peaks is that the third peak has a temperature cutoff of 1000°C, so the corresponding DSC and TGA are incomplete. From the trend, there will be a large weight loss and heat energy, and the gas chromatography-mass spectrometry GCMS begins to have larger peaks, indicating that the material has begun to completely decompose.

[0061] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A quasi-in-situ joint analysis method for battery materials, characterized in that: Including synchronous thermal analyzer STA and gas chromatography-mass spectrometry GCMS, The synchronous thermal analyzer STA is used to analyze the thermogravimetry, temperature and thermal enthalpy of battery materials. The synchronous thermal analyzer STA heats mg-level battery material samples at a constant rate in an inert gas environment, and detects the changes in heat flow and weight to obtain the curves of the weight, temperature and thermal enthalpy of the battery materials over time; The gas chromatograph-mass spectrometer GCMS is used to analyze the decomposed material products. The gas products of thermal decomposition from the synchronous thermal analyzer STA enter the gas chromatograph-mass spectrometer GCMS through a high-temperature connecting tube. The gas chromatograph-mass spectrometer GCMS provides a programmed temperature increase for the gas products, and the gas is subjected to component analysis during the temperature increase. The synchronous thermal analyzer STA and the gas chromatography-mass spectrometer GCMS form a joint analysis device; The battery material is a solid electrolyte in different states obtained by assembling a battery for charging and discharging, and the combined analysis device is used to detect the quasi-in-situ characterization of the solid electrolyte.

2. The quasi-in-situ combined analysis method for battery materials according to claim 1, characterized in that: The air outlet of the synchronous thermal analyzer STA is connected to the air inlet of the high-temperature connecting pipe. The gas outlet of the high temperature connecting tube is connected to the sample inlet of a gas chromatograph-mass spectrometer GCMS.

3. The quasi-in-situ joint analysis method for battery materials according to claim 1, characterized in that: The analysis steps of the joint detection and analysis device include: Step (1) assembling different batteries with different positive and negative electrodes, separators, and electrolytes, and then subjecting the batteries to charge and discharge experiments with different currents, thereby obtaining positive and negative electrodes and separator samples in different states through charging or discharging; Step (2) disassembling, cleaning and drying the positive and negative electrodes and the separator samples in different states under the protection of an inert atmosphere to obtain the samples in different states; Step (3) transfers the sample to a combined analysis device for testing, thereby achieving quasi-in-situ detection of the sample under different states.

4. The quasi-in-situ combined analysis method for battery materials according to claim 3, characterized in that: The step (1) comprises: Step (1-1) The positive electrode material is prepared to be a positive electrode sheet, and the negative electrode material is prepared to be a negative electrode sheet, and a positive electrode sheet + a separator + a negative electrode sheet are stacked to obtain a battery; Step (1-2) connects the above battery to a charger and discharger, and performs charging and discharging according to different charging and discharging conditions. After completion, the solid electrolyte state is locked by powering off to obtain positive electrode, negative electrode, and diaphragm samples in different states.

5. The quasi-in-situ combined analysis method for battery materials according to claim 4, characterized in that: The positive and negative electrodes include a plurality of pole pieces with predetermined proportions and predetermined thicknesses.

6. The quasi-in-situ combined analysis method for battery materials according to claim 4, characterized in that: The step (2) comprises: (2-1) After the charge and discharge experiment is completed, the battery is removed and disassembled in an inert gas to obtain the positive and negative electrodes and the separator; (2-2) The solid electrolyte sheet was cleaned 3-4 times with a cleaning agent dimethyl carbonate solvent (DMC, >99.5%) in an inert gas atmosphere and dried for more than 12 hours to obtain the samples in different states.

7. The quasi-in-situ combined analysis method for battery materials according to claim 1, characterized in that: The synchronous thermal analyzer STA is a PE synchronous thermal analyzer STA8000 from the United States, and the gas chromatograph-mass spectrometer GCMS is a PE Clarus590 / SQ8T from the United States.

8. The quasi-in-situ combined analysis method for battery materials according to claim 4, characterized in that: The step (3) comprises: (3-1) Open the sample compartment door of the synchronous thermal analyzer STA, place an empty crucible and reset to zero; (3-2) Take out the empty crucible and add a certain amount of sample (solid, liquid, or solid + liquid) about 1-10 mg. If the sample requires an inert atmosphere, the operation should be carried out in a glove box with the door closed; (3-3) Weigh the specific mass on the synchronous thermal analyzer STA, adjust the gas flow rate to 50 ml / min, set the equilibration time to 10 min, and set the heating rate to 20 °C / min to 1000 °C (the specific heating rate and final temperature can be changed according to the material properties). After starting the operation, call the gas chromatography-mass spectrometry (GCMS) method parameters within the equilibration time.

9. The quasi-in-situ combined analysis method for battery materials according to claim 8, characterized in that: (3-3) The decomposition products can be scanned for all possible substances using Scan mode or for specific substances using SIM mode.

10. The quasi-in-situ combined analysis method for battery materials according to claim 8, characterized in that: The gas chromatography-mass spectrometry (GCMS) analysis conditions include the following parameters: Inlet: 260°C, flow rate 1 ml / min, split ratio 10:1, gas saver closed; Hollow chromatographic column: 10m*250μm*0μm; Column box: 250℃, maintain 999min; Mass spectrometry: solvent delay 2.5 min, ion source temperature 230 °C, quadrupole temperature 150 °C, full scan using Scan mode, characteristic ion scan using SIM mode, mass-to-charge ratios of 10, 16, 18, 28, 30, 32, 42, 44, 48, 86, 88, 104, and 126 ions selected for monitoring.

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