A method for analyzing the operating status of aqueous zinc-ion batteries

Abstract

This invention discloses a method for analyzing the operating state of an aqueous zinc-ion battery. The method includes the following steps: S1, simultaneously analyzing the electrolyte and the cathode of the aqueous zinc-ion battery under test; wherein, inductively coupled plasma mass spectrometry (ICP-MS) is used to analyze the electrolyte of the aqueous zinc-ion battery in its operating state to obtain the electrolyte analysis results; time-of-flight secondary ion mass spectrometry (TOF-MS) is used to analyze the cathode of the aqueous zinc-ion battery in its operating state to obtain the cathode analysis results; S2, combining the electrolyte analysis results and the cathode analysis results, the operating state of the aqueous zinc-ion battery is comprehensively detected in real time, and the test results are obtained. This method uses a combination of inductively coupled plasma mass spectrometry and time-of-flight secondary ion mass spectrometry to analyze the operating state of the aqueous zinc-ion battery, which can achieve real-time, accurate, and effective detection of the operating status of the aqueous zinc-ion battery.

Description

Technical Field

[0001] This invention belongs to the field of battery testing technology, specifically relating to a method for analyzing the working state of an aqueous zinc-ion battery. Background Technology

[0002] With rapid societal development, the depletion of traditional energy sources has further accelerated research into clean and renewable energy. Unlike the rapidly developing lithium-ion batteries, zinc-ion batteries (ZIBs) are rapidly emerging as a type of aqueous secondary battery. Aqueous zinc-ion batteries offer higher safety and lower cost than lithium-ion batteries, and higher energy density than lead-acid batteries, making them excellent energy storage devices capable of playing a crucial role in mobile energy storage and large-scale energy storage sites. However, the detection of the operating state of aqueous zinc-ion batteries is still constrained by several factors. During operation, redox reactions occur at the positive electrode of aqueous zinc-ion batteries, such as the insertion and extraction of H or Zn, which are difficult to observe directly using traditional detection methods. To achieve high lifespan, high stability, and wearability of zinc-ion batteries, greater attention must be paid to strategies for detecting the operating state of aqueous zinc-ion batteries.

[0003] To date, several strategies have been proposed for detecting the operational status of aqueous zinc-ion batteries, such as combining in-situ electrochemical mass spectrometry (DEMS) with gas chromatography (GC), using synchrotron X-ray absorption spectroscopy (XAS) with mass spectrometry (MS), and in-situ optical-Raman-mass spectrometry. However, the current analytical procedures do not cover all the necessary tests, which affects the cause analysis process and may even lead to incorrect attribution. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a method for analyzing the operating status of aqueous zinc-ion batteries. This method utilizes a combination of inductively coupled plasma mass spectrometry (ICP-MS) and time-of-flight secondary ion mass spectrometry (TOF-MS) to analyze the operating status of aqueous zinc-ion batteries, enabling real-time, accurate, and effective detection of their operational status.

[0005] The present invention adopts the following technical solution:

[0006] A method for analyzing the operating state of an aqueous zinc-ion battery includes the following steps:

[0007] S1. Simultaneously analyze the electrolyte and cathode of the aqueous zinc-ion battery under test; specifically, use inductively coupled plasma mass spectrometry to analyze the electrolyte of the aqueous zinc-ion battery in the working state, and obtain the electrolyte analysis results; use time-of-flight secondary ion mass spectrometry to analyze the cathode of the aqueous zinc-ion battery in the working state, and obtain the cathode analysis results.

[0008] S2. By combining the analysis results of the electrolyte and the positive electrode, the working status of the aqueous zinc-ion battery is monitored in real time, and the test results are obtained through analysis.

[0009] Preferably, in step S1, an inductively coupled plasma mass spectrometer is used to detect the element content of the electrolyte in the aqueous zinc-ion battery during operation. The elements detected include one or more of Zn, Mn, V, Fe, P, and S.

[0010] Preferably, in step S1, a time-of-flight secondary ion mass spectrometer is used to detect ion fragments generated at the positive electrode of the aqueous zinc-ion battery in real time during operation. The detected ion fragments include ion fragments of the positive electrode used and by-product ion fragments.

[0011] Preferably, in step S1, before using an inductively coupled plasma mass spectrometer for detection, if the electrolyte is an organic electrolyte or a mixed electrolyte, the electrolyte is first diluted with pure water until the proportion of organic components is less than 10%; if the content of metal elements in the electrolyte is greater than the threshold, the sample concentration is diluted to between 1 and 10 ppm to improve the test sensitivity.

[0012] Preferably, step S2 involves comparing the electrolyte analysis results with the cathode analysis results. If the content of the main elements of the cathode active material in the electrolyte is greater than a threshold, and the rate at which the percentage of the main ion fragments of the cathode active material decreases with depth is greater than a threshold, it indicates that the cathode has high solubility in the electrolyte during the electrochemical process and poor recovery ability after one charge-discharge cycle. Conversely, it indicates that the cathode has high solubility in the electrolyte and good recovery ability. If there are non-initial cathode component ion fragments in the cathode, it indicates the presence of Zn during the electrochemical process. 2+ and H + Embedded, and gradually decreasing along the longitudinal depth; the greater the longitudinal depth, the higher the proportion of VO2(B) fragments, indicating that the effective active substances are better preserved; if the percentage content of electrolyte component fragments on the surface is high, and the rate of increase with depth is less than the threshold, it indicates that the electrolyte salts are severely decomposed on the surface.

[0013] After adopting the above technical solution, the present invention has the following advantages compared with the prior art: The present invention first uses inductively coupled plasma mass spectrometry (ICP-MS), which is an inorganic multi-element analysis technique that uses inductively coupled plasma as an ion source and mass spectrometry for detection. ICP-MS uses argon (Ar) plasma, in which ICP converts the sample into ions, and then mass spectrometry (MS) is used for measurement. Then, the time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a high-resolution measurement technique that uses primary ions to excite the sample surface and ejects extremely small amounts of secondary ions. The ion mass is determined by the different flight times of the secondary ions due to their different masses. The unique feature of TOF is that its ion flight time depends only on their mass. Since a full spectrum can be obtained with a single pulse, the ion utilization rate is the highest, and it can best achieve almost non-destructive static analysis of the sample. It is a very good characterization method for aqueous zinc-ion battery cathodes in detection work. Therefore, this method uses a combination of inductively coupled plasma mass spectrometry (ICP-MS) and time-of-flight secondary ion mass spectrometry (TOF-MS) to analyze the operating status of aqueous zinc-ion batteries. It can analyze the battery under test during operation, confirming changes in cathode composition with depth, the amount of cathode active material dissolved in the electrolyte, changes in electrolyte composition, and material degradation. Through simple testing, a comprehensive analysis of the operating status of aqueous zinc-ion batteries can be performed, accurately obtaining the battery's operating condition and enabling timely responses. This allows for real-time, accurate, and effective detection of the operating status of aqueous zinc-ion batteries. Attached Figure Description

[0014] Figure 1 These are all fragment spectra obtained by TOF-SIMS testing in this invention;

[0015] Figure 2 This refers to the total number of fragments obtained by TOF-SIMS testing in this invention.

[0016] Figure 3 This is a graph showing the variation of the content of four ionic fragments—ZnO-, OH-, VO-, and ZnF2-—with sample depth in this invention.

[0017] Figure 4 This is a 3D schematic diagram of the content distribution of four ion fragments, ZnO-, OH-, VO-, and ZnF2-, drawn using 3Dmax according to the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] See Figures 1 to 4.

[0020] Example 1

[0021] Preparation of aqueous zinc-ion batteries

[0022] A full cell was prepared using VO2(B) as the positive electrode active material, water as the solvent, and a 1 mol / L Zn(CF3SO3)2 eutectic electrolyte:

[0023] Electrolyte preparation: A certain amount of Zn(CF3SO3)2 was added to ultrapure water to prepare an electrolyte with a concentration of 1 mol / L Zn(CF3SO3)2.

[0024] Preparation of the positive electrode active material: VO2(B) nanorods were prepared via a hydrothermal method. A typical synthesis involved adding 3 mmol of V2O5 powder to 30 mL of deionized water and stirring for 10 minutes, followed by the addition of 1 mmol of glucose and continued stirring for another 10 minutes. The homogeneous dispersion was then added to a 50 mL Teflon-lined autoclave, heated to 180 °C, and maintained for 24 hours to obtain a black powder. After sonication with dimethyl sulfoxide (DMSO), the powder was washed with deionized water and ethanol, and dried at 80 °C to obtain VO2(B).

[0025] Current collector pretreatment: Stainless steel foil is used as the current collector for VO2(B) positive electrode. A 10 cm wide stainless steel foil is cut from the stainless steel foil roll. The surface and edges of the stainless steel foil are flattened using an electric double roller press. The foil is then ultrasonically cleaned with alcohol for 10 minutes, and the cleaning is repeated twice.

[0026] Binder preparation: PVDF is used as a binder for the VO2(B) positive electrode. A certain amount of PVDF and N-methylpyrrolidone are accurately weighed into a beaker at a ratio of 1:25 and placed on a magnetic stirrer to be stirred and mixed evenly at a speed of 600 rpm / min.

[0027] Accurately weigh a certain amount of active material VO2(B), conductive carbon black, and binder into a 10ml beaker at a mass ratio of 7:2:1. Seal the beaker with sealing film, then add approximately 4ml of N-methylpyrrolidone until the slurry can be stirred normally. Place the prepared slurry on a magnetic stirrer and stir continuously for 12 hours to obtain a uniformly mixed positive electrode slurry. Then, spread the slurry onto a pretreated stainless steel foil and use a four-sided scraper with a 150μm gap to evenly spread the slurry. Place the stainless steel foil with the slurry in a vacuum oven at 80℃ and dry for at least 12 hours. After it has completely cooled to room temperature, remove it and use a battery electrode slicing machine to cut the electrode into 12mm diameter pieces. Place them in a sealed bag in a desiccator for later use.

[0028] (3) Negative electrode preparation process: Commercially available pure zinc sheets are cut into 10cm square pieces and then fed into an electric roller press to flatten the surface and edges of the zinc sheets to a usable thickness of 80μm. The sheets are then placed in an ultrasonic cleaner and cleaned with acetone, ethanol, and deionized water respectively. After cleaning, the zinc sheets are placed in a vacuum drying oven at 60℃ for 3 hours. The cooled zinc sheets are then removed and cut into 12mm diameter pieces to obtain usable negative electrode sheets.

[0029] (4) Button Cell Assembly Process: All operations in the button cell assembly process are carried out in an air atmosphere, as detailed below: 1) Zinc-Zinc Symmetrical Battery: Zinc sheet, glass fiber separator, zinc sheet, and stainless steel sheet (SS) are placed sequentially into the CR2032 negative electrode battery case, then a spring clip is placed on top, the CR2032 positive electrode battery case is covered, and the battery is placed in a button cell packaging machine for sealing. 2) Positive Electrode (VO2(B))-Zinc Battery: Zinc sheet, glass fiber separator, positive electrode sheet, and stainless steel sheet (SS) are placed sequentially into the CR2032 negative electrode battery case, then a spring clip is placed on top, the CR2032 positive electrode battery case is covered, and the battery is placed in a button cell packaging machine for sealing. During sealing, the sealing pressure of the button cell packaging machine must be greater than 50 kg / cm². 3 The duration is 10 seconds. When encapsulating the positive electrode (VO2(B))-zinc battery, a padding paper needs to be placed on top of the battery to prevent the formation of a circuit outside the battery during encapsulation. The newly encapsulated battery cannot be used immediately and must be left to stand for more than 2 hours to allow sufficient contact between the electrode / electrolyte interface before testing.

[0030] Example 2

[0031] Operating status analysis and testing of aqueous zinc-ion batteries

[0032] The button cell prepared in Example 1 was placed in the Xinwei Battery Testing System and subjected to a 0.5 A·g test. -1 Constant current cycling was performed, and the test was conducted after 30 cycles.

[0033] There is no need to interrupt the normal operation of the battery. Take a small amount of electrolyte and dilute it 80 times. Use inductively coupled plasma mass spectrometry (ICP-MS) to test the content of Zn and V elements in the diluted electrolyte. Perform three tests on average. Calculate the relative standard deviation (RSD) of the six concentration data obtained. An RSD of less than 1% is considered an accurate result. The test results of the electrolyte of aqueous zinc-ion battery in working state by inductively coupled plasma mass spectrometry (ICP-MS) are shown in Table 1.

[0034] Table 1: Test results of electrolyte in aqueous zinc-ion batteries under operating conditions using inductively coupled plasma mass spectrometry (ICP-MS)

[0035]

[0036]

[0037] As shown in Table 1, the Zn content can be obtained by converting the percentage of solubility. 2+ The concentration was 1.018 mol·L⁻¹ -1 This indicates that some Zn at the negative electrode dissolves in the electrolyte, but this is within the normal range. Calculations based on the percentage dissolution rate yielded a V dissolution rate of 43.68 μg·L⁻¹. -1 This indicates that some vanadium dioxide from the positive electrode dissolves in the electrolyte, but the amount is small and does not affect the normal operation of the aqueous zinc-ion battery.

[0038] The sputtered atoms were Cs atoms, sputtered at an energy of 1 keV 80 nA, and received by a Bi3 atom group in negative ion mode using a time-of-flight secondary ion mass spectrometer (TOF-SIMS). ++ The receiving energy was 30 keV, the receiving fragment range was 2-1000 u, and the effective material of the positive electrode surface with a length and width of 50 μm × 50 μm and a depth of 200 nm was used for testing, and the compound fragment count was obtained.

[0039] Test results are as follows Figures 1-4 As shown, Figure 1 The images are of all fragment spectra obtained using TOF-SIMS testing. Figure 2 This is a graph showing the total number of fragments obtained using the TOF-SIMS test. Figure 3 The graph shows the variation of the content of four ion fragments—ZnO-, OH-, VO-, and ZnF2-—with sample depth. Figure 4 This is a 3D schematic diagram of the content distribution of four ion fragments: ZnO-, OH-, VO-, and ZnF2-, generated using 3DMax. Figures 1-4 Therefore, the VO2(B) cathode of the aqueous zinc-ion battery contains Zn during operation. 2+ and H + The embedding depth gradually decreases along the longitudinal direction; the greater the longitudinal depth, the higher the proportion of VO2(B) fragments, indicating that the effective active material is better preserved; the percentage content of ZnF2- fragments on the surface is high, and decreases sharply with increasing depth, indicating that the electrolyte salt Zn(OTf)2 is severely decomposed on the surface.

[0040] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for analyzing the working state of an aqueous zinc-ion battery, characterized in that, Comprising the following steps: S1, simultaneously electrolyte analysis and positive electrode analysis are performed on the water-based zinc ion battery to be tested; wherein, the electrolyte of the water-based zinc ion battery in the working state is analyzed by using an inductively coupled plasma mass spectrometer to obtain an electrolyte analysis result; the positive electrode of the water-based zinc ion battery in the working state is analyzed by using a time-of-flight secondary ion mass spectrometer to obtain a positive electrode analysis result; In step S1, the inductively coupled plasma mass spectrometer is used to detect the element content of the electrolyte of the water-based zinc ion battery in the working state in real time, and the detected elements include one or more of Zn elements, Mn elements, V elements, Fe elements, P elements and S elements; In step S1, the time-of-flight secondary ion mass spectrometer is used to detect the ion fragments generated by the positive electrode of the water-based zinc ion battery in the working state in real time, and the detected ion fragments include ion fragments and byproduct ion fragments of the positive electrode used; In step S1, before detection by the inductively coupled plasma mass spectrometer, if the electrolyte is an organic electrolyte or a mixed electrolyte, the electrolyte is first diluted with pure water until the proportion of the organic component is less than 10%; if the metal element content in the electrolyte is greater than a threshold value, the sample concentration is diluted to between 1-10 ppm to improve the test sensitivity; S2, the electrolyte analysis result and the positive electrode analysis result are combined to comprehensively detect the working state of the water-based zinc ion battery in real time, and a test result is obtained by analysis; The specific process of step S2 is: comparing and analyzing the electrolyte analysis result and the positive electrode analysis result, if the content of the main elements of the positive electrode active material in the electrolyte is greater than a threshold value, and the rate of the percentage of the main ion fragments of the positive electrode active material decreasing with the depth is greater than a threshold value, it indicates that the solubility of the positive electrode in the electrolyte is high in the electrochemical process, and the recovery ability is poor after experiencing a charging and discharging cycle, otherwise it indicates that the solubility of the positive electrode in the electrolyte is low, and the recovery ability is good; if there are non-initial positive electrode component ion fragments in the positive electrode, it indicates that Zn 2+ and H + are embedded in the electrochemical work, and gradually decrease along the longitudinal depth; the greater the longitudinal depth, the higher the percentage of VO2(B) fragments, indicating that the effective active material is better maintained; if the percentage of the electrolyte component fragments is high on the surface, and the rate of increasing with the depth is less than a threshold value, it indicates that the electrolyte salt is seriously decomposed on the surface.

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