A lithium supplement negative electrode utilization rate quantitative detection method based on gas chromatography technology

Abstract

The application provides a lithium supplement negative electrode utilization rate quantitative detection method based on gas chromatography technology, comprising the following steps: S1, establishing a first standard curve of hydrogen volume and gas chromatography hydrogen peak area; S2, establishing a second standard curve of metal lithium mass and total hydrogen molar quantity; S3, calculating the total active lithium mass in the lithium supplement electrode sheet according to the first standard curve and the second standard curve; S4, calculating the residual lithium mass of the lithium extraction electrode sheet according to the first standard curve and the second standard curve; and S5, calculating the lithium utilization rate m of the lithium supplement negative electrode by using a formula total =(m toal ‑m residua ) / m motal . The application can accurately determine the total active lithium mass and the residual lithium mass in the lithium supplement negative electrode, and realizes accurate quantification of the lithium supplement utilization rate.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a quantitative detection method for the utilization rate of lithium-ion anodes based on gas chromatography technology. Background Technology

[0002] During the first charge of a lithium-ion battery, a solid electrolyte interphase (SEI) film forms on the surface of the negative electrode. This process consumes active lithium from the positive electrode, leading to a decrease in the battery's initial coulombic efficiency and an increase in irreversible capacity loss. To compensate for this loss, lithium replenishment technology has emerged. By pre-storing a certain amount of active lithium at the negative electrode to compensate for the lithium ions consumed in the formation of the SEI film, the initial coulombic efficiency and energy density of the battery can be effectively improved. Common methods for negative electrode lithium replenishment include calendering, vapor deposition, and spraying, which introduce a metallic lithium layer onto the surface of graphite, silicon-carbon, or silicon-oxygen negative electrodes to achieve pre-lithiation.

[0003] Currently, the utilization rate assessment of lithium replenishment anodes mainly relies on a method combining electrochemical testing and model estimation. This method typically takes the amount of lithium released during the initial electrochemical delithiation process, plus the amount of lithium consumed in the formation of the SEI film, as the amount of lithium that is reasonably utilized; and uses the total lithium metal content in the lithium replenishment electrode as the total lithium content. The ratio of the two is the lithium replenishment utilization rate. However, this calculation method has obvious limitations: First, during the lithium replenishment process between the negative electrode and lithium sheet or foil, not all lithium metal exists in an active form. Some lithium metal reacts with residual oxygen or moisture in the air and is oxidized to form inert compounds such as lithium carbonate. This portion of lithium cannot participate in the lithium replenishment process of the negative electrode, but it is included in the total lithium amount in the traditional calculation method, leading to an underestimation of utilization. Second, during the lithium replenishment reaction between the negative electrode and lithium metal, intermediate phases such as lithium-carbon compounds or lithium-silicon compounds are formed. These compounds cannot be completely removed electrochemically during the first delithiation process, but are slowly released during subsequent cycles. The traditional method ignores them, which also affects the accuracy of utilization assessment. In addition, after delithiation, there may still be dead lithium that did not participate in the reaction and residual lithium that failed to be removed from the metal compounds in the electrode, which is difficult to quantitatively detect using the traditional method.

[0004] In summary, existing methods for evaluating lithium replenishment utilization based on electrochemical testing cannot distinguish between different forms of lithium in the lithium replenishment electrode, making it difficult to accurately reflect the actual effect of the lithium replenishment process. Summary of the Invention

[0005] To address the issue of low accuracy in existing methods for evaluating the utilization rate of lithium replenishment in negative electrodes, this invention provides a quantitative detection method for lithium replenishment utilization in negative electrodes based on gas chromatography technology, comprising the following steps:

[0006] Step S1: Establish the first standard curve of hydrogen volume versus hydrogen peak area in gas chromatography;

[0007] Step S2: Place metallic lithium and deionized water in a sealed reaction vessel to generate hydrogen gas, and then establish a second standard curve of metallic lithium mass versus total molar amount of hydrogen gas.

[0008] Step S3: Place the lithium-added negative electrode sheet and deionized water in a sealed reaction vessel. After the reaction is complete, extract the gas from the upper layer of the vessel and inject it into a gas chromatograph to obtain the hydrogen peak area. Then, calculate the total mass of active lithium in the lithium-added electrode sheet based on the first and second standard curves. ;

[0009] Step S4: Assemble the lithium-added negative electrode into a half-cell and perform electrochemical delithiation treatment. Then, place the delithiated electrode in a sealed reaction vessel and add deionized water. After the reaction is complete, extract the gas from the upper layer of the reaction vessel and inject it into a gas chromatograph for detection. Record the hydrogen peak area, and then calculate the residual lithium mass of the delithiated electrode according to the first and second standard curves. ;

[0010] Example S5: Calculating the lithium utilization rate of the lithium-added anode using a formula ,

[0011]

[0012] To improve lithium utilization in the lithium anode, To replenish the total mass of active lithium in the lithium electrode, The residual lithium mass of the delithiation electrode.

[0013] Further, the process of establishing the second standard curve in step S2 is as follows: First, lithium metal and deionized water are placed in a sealed reaction vessel. After the reaction is complete, the gas in the upper layer of the vessel is extracted and injected into a gas chromatograph to obtain the hydrogen peak area. Then, the volume of hydrogen in the extracted gas is calculated according to the first standard curve, and the total volume of hydrogen produced in the reaction vessel is calculated in combination with the volume of the space at the top of the reaction vessel. Then, the total volume of hydrogen is converted into the total molar amount of hydrogen according to the ideal gas equation, and a second standard curve is established between the mass of lithium metal and the total molar amount of hydrogen.

[0014] Furthermore, the relationship of the first standard curve in step S1 is as follows:

[0015]

[0016] Where A is the peak area of ​​hydrogen gas. Let be the volume of hydrogen gas, and a and b be fitting constants.

[0017] Furthermore, the relationship of the second standard curve in step S2 is as follows:

[0018]

[0019] in, This represents the total molar amount of hydrogen gas in the reaction vessel. denoted as the mass of lithium metal, and k as a proportionality coefficient.

[0020] Further, the formula for calculating the total volume of hydrogen in the reaction vessel in step S2 is as follows:

[0021]

[0022] in, This represents the volume of hydrogen gas detected by gas chromatography. This refers to the volume of the space at the top of the reaction vessel. This represents the volume of gas drawn by the syringe.

[0023] Furthermore, the volume of the space at the top of the reactor The calculation formula is:

[0024]

[0025] in, This refers to the total volume of the reaction vessel. This refers to the volume of deionized water injected.

[0026] Furthermore, in step S3, the total molar amount of hydrogen and the total volume of hydrogen in the reaction vessel conform to the ideal gas law, and the conversion relationship is as follows:

[0027]

[0028] in, This represents the total molar amount of hydrogen gas in the reaction vessel. One standard atmosphere Let T be the total volume of hydrogen, T be the Kelvin temperature, and R be the molar gas constant.

[0029] Furthermore, the conditions for electrochemical delithiation treatment in step S4 are as follows: the half-cell assembled with the lithium-replenishing electrode is charged to 1.5-2.5V under constant current and constant voltage at a current density of 0.01C to 0.1C.

[0030] Furthermore, the reaction vessel is a vial.

[0031] Further, the specific operation of step S1 is to take hydrogen standard gas samples of different volumes, inject them into the gas chromatograph respectively, and record the corresponding hydrogen peak area. Using the hydrogen volume as the abscissa and the peak area as the ordinate, a first standard curve relationship between the hydrogen volume and the gas chromatographic signal peak area is obtained by linear fitting.

[0032] This invention utilizes the characteristic of active lithium reacting with water to generate hydrogen gas, enabling direct quantitative detection of the active lithium content in a sample. This overcomes the limitations of traditional methods and provides a new technical path for evaluating the utilization rate of lithium-added anodes. Furthermore, it enables accurate determination of the total active lithium and residual lithium content in the lithium-added anode, thereby accurately calculating the lithium utilization rate and improving the accuracy of lithium-added utilization rate calculation. Attached Figure Description

[0033] Figure 1 This is a flowchart of the method for quantitative detection of negative electrode lithium replenishment utilization based on gas chromatography technology according to the present invention;

[0034] Figure 2 This is a standard curve showing the relationship between hydrogen volume and hydrogen signal area in the detection method of this invention.

[0035] Figure 3 This is a standard curve showing the relationship between the mass of lithium metal and the molar amount of hydrogen in the detection method of this invention. Detailed Implementation

[0036] The following detailed description, in conjunction with specific embodiments, further illustrates the present invention. It should be understood that the embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0037] The materials and instruments used in this embodiment mainly include lithium-ion negative electrode sheets, a gas chromatograph, and a glove box. The specifications and properties of various materials are as follows.

[0038] Lithium-replenished negative electrode sheet: In this embodiment, the lithium-replenished negative electrode sheet can be obtained by lithium replenishment treatment of graphite negative electrode, silicon-carbon negative electrode, or silicon-oxygen negative electrode using at least one of the following methods: calendering, vapor deposition, and spraying. Preferably, lithium is replenished on the surface of graphite negative electrode using calendering. The thickness of the lithium replenishment layer of the lithium-replenished negative electrode sheet is 1~10 μm, preferably 1~3 μm. The lithium-replenished negative electrode sheet used in subsequent tests is cut into a regular shape, so that the powder does not need to be scraped off, thus maintaining the original distribution state of the lithium replenishment layer. Preferably, the electrode sheet is cut into small circular pieces with a diameter of 12 mm.

[0039] Gas chromatograph: The gas chromatograph used in this embodiment is equipped with a thermal conductivity detector (TCD) or a flame ionization detector (FID). The carrier gas is at least one of high-purity nitrogen, argon or helium, preferably argon. The chromatographic column is an Al2O3 capillary column.

[0040] Seal the reaction vessel: 30 mL vial, fitted with a rubber stopper and aluminum cap, and seal using crimping pliers.

[0041] Syringe: In this embodiment, a graduated, airtight syringe is used to extract the gas from the upper layer of the reaction vessel and inject it into the gas chromatograph detector. The volume of gas extracted by the syringe in this embodiment is much smaller than the volume of the space at the top of the reaction vessel, so even if multiple extractions are performed, the effect on the pressure inside the reaction vessel can be ignored.

[0042] Glove box: A high-purity argon atmosphere glove box with both water and oxygen content below 0.1 ppm.

[0043] The detection method of the present invention is operated according to the following steps:

[0044] Step S1: Establish a first standard curve relating hydrogen volume to the hydrogen peak area in gas chromatography.

[0045] Different volumes of hydrogen standard gas samples of specific concentrations were injected into the gas chromatograph, and the signal areas of the corresponding hydrogen characteristic peaks were recorded. The first standard curve relationship between hydrogen volume and gas chromatographic signal area was obtained by fitting the data.

[0046] In this embodiment, 100, 200, 300, 400, and 500 μL of hydrogen standard gas with a volume fraction of 0.976% were injected into the gas chromatograph using an airtight syringe and detected. The peak area of ​​the hydrogen characteristic peak was recorded. The hydrogen volume was calculated using the following formula: ,in This represents the standard volume of hydrogen gas.

[0047] The test results are shown in Table 1:

[0048] <![CDATA[(V 标 Standard volume of hydrogen gas (μL) <![CDATA[(V H2 Hydrogen volume (μL) (A) Hydrogen peak area (μV⋅s) 100 0.976 161.1 200 1.952 320.4 300 2.928 500.5 400 3.904 678.9 500 4.88 850.5

[0049] With hydrogen volume (V) H2 Using (A) as the x-axis and the hydrogen peak area (A) as the y-axis, a linear fit was performed. The result of the linear fit is shown below. Figure 2 As shown, the equation of the first standard curve is obtained as follows:

[0050]

[0051] Where A is the peak area of ​​hydrogen gas. Let be the volume of hydrogen gas, and a and b be fitting constants.

[0052] In this embodiment, a equals 178, and b equals -18.91. In this embodiment, the first standard curve relating hydrogen volume to the hydrogen peak area in gas chromatography is:

[0053]

[0054] The first standard curve obtained in this embodiment shows the linear correlation coefficient R between the hydrogen peak area and the hydrogen volume. 2 =0.999.

[0055] Step S2: Place lithium metal and deionized water in a sealed reaction vessel. After the reaction is complete, extract the gas from the upper layer of the vessel and inject it into a gas chromatograph to obtain the hydrogen peak area. Calculate the volume of hydrogen in the extracted upper layer gas according to the first standard curve, and calculate the total volume of hydrogen produced in the reaction vessel by combining the volume of the space at the top of the reaction vessel. Then, convert the total volume of hydrogen into the total molar amount of hydrogen according to the ideal gas equation, and establish a second standard curve of lithium metal mass versus total molar amount of hydrogen.

[0056] Step S2 is performed as follows: Weigh different masses of lithium metal in an inert atmosphere glove box and place them in sealed reaction containers. Inject a known volume of excess deionized water to allow for complete reaction. Then, extract the gas from the upper layer of the container and inject it into a gas chromatograph for detection. Record the peak area of ​​the generated hydrogen gas. Calculate the volume of hydrogen gas in the extracted gas according to the first standard curve. Combine this with the volume of the space at the top of the reaction container to calculate the total volume of hydrogen gas generated in the container. Then, convert the total volume of hydrogen gas into the total molar amount of hydrogen gas according to the ideal gas law (set the ambient temperature to room temperature of 25℃ and atmospheric pressure to 101 kPa). Perform linear fitting with the mass of lithium metal as the x-axis and the total molar amount of hydrogen gas as the y-axis to obtain the linear relationship between the mass of lithium metal and the total molar amount of hydrogen gas.

[0057] Specifically, in a glove box, 1.5 mg, 1.8 mg, 2.1 mg, 2.4 mg, and 2.7 mg of lithium metal were weighed using a precision balance and quickly transferred to 30 mL vials. The vials were sealed with rubber stoppers, and the glove box was removed. 0.5 mL of deionized water was injected into each vial using a syringe, and the mixture was allowed to stand for 30 minutes to allow the reaction to complete. 0.5 mL of the upper gas layer in the reaction flask was extracted using a gas-tight syringe and injected into a gas chromatograph for detection. The hydrogen peak area was recorded. The hydrogen volume was calculated based on the first standard curve.

[0058]

[0059] Where V H2 The volume of hydrogen gas drawn by the syringe is the volume of hydrogen gas detected by gas chromatography, and A is the hydrogen peak area detected by the gas chromatograph.

[0060] Calculate the total volume V of hydrogen produced inside the sealed reaction vessel by combining the volume of the top space of the sealed reaction vessel. total :

[0061]

[0062] Among them, V total This refers to the total volume of hydrogen gas produced inside the sealed container. V is the volume of gas drawn by the syringe. H2The volume of hydrogen gas drawn by the syringe is the same as the volume of hydrogen gas detected by the gas chromatograph. This refers to the volume of the space at the top of the reaction vessel. .

[0063] in This refers to the total volume of the reaction vessel. This refers to the volume of deionized water injected.

[0064] In this embodiment, V total The calculation result is,

[0065]

[0066] Based on the ideal gas law (room temperature 25℃, atmospheric pressure 101 kPa), convert the total volume of hydrogen to the total molar amount of hydrogen, n. H2 :

[0067]

[0068] in This represents the total molar amount of hydrogen gas in the reaction vessel. One standard atmosphere Let T be the total volume of hydrogen, T be the Kelvin temperature, and R be the molar gas constant.

[0069] The specific data results for each embodiment in this example are shown in Table 2:

[0070] Mass of lithium metal (mg) Hydrogen peak area (μV⋅s) Total volume of hydrogen (μL) Total moles of hydrogen (mmol) 1.5 7957.3 2644 0.1081 1.8 9552.7 3173 0.1297 2.1 11147.8 3701 0.1513 2.4 12743.2 4230 0.1728 2.7 14338.2 4759 0.1947

[0071] With lithium metal mass m Li The x-axis represents the total molar amount of hydrogen in the reaction vessel, n. H2 Using the ordinate as the vertical axis, a linear fit is performed, and the result of the linear fit is as follows: Figure 3 As shown, the general equation for the second standard curve is:

[0072]

[0073] in This represents the total molar amount of hydrogen gas in the reaction vessel. Where is the mass of lithium metal, and k is a proportionality coefficient. In this embodiment...

[0074]

[0075] The second standard curve obtained from the above embodiments shows the linear correlation coefficient R between the mass of lithium metal and the total molar amount of hydrogen. 2 =0.998.

[0076] Step S3: Place the lithium-added negative electrode sheet and deionized water in a sealed reaction vessel. After the reaction is complete, extract the gas from the upper layer of the vessel and inject it into a gas chromatograph to obtain the hydrogen peak area. Then, calculate the total mass of active lithium in the lithium-added electrode sheet directly based on the first and second standard curves. .

[0077] In the glove box, take three lithium anode plates (12 mm in diameter) and place them into three separate vials. Seal the vials and remove the glove box. Inject 5 mL of deionized water into each vial using a syringe and let stand for 30 min. Use a gas-tight syringe to extract 0.5 mL of the upper gas layer from the reaction vial and inject it into a gas chromatograph for detection. Record the hydrogen peak area.

[0078] The hydrogen volume was calculated based on the first standard curve:

[0079]

[0080] Calculate the total volume of hydrogen produced inside the container by combining the volume of the top space of the reaction vessel:

[0081]

[0082] Convert the total volume of hydrogen to the total molar amount of hydrogen using the ideal gas law (room temperature 25℃, atmospheric pressure 101 kPa):

[0083]

[0084] The mass of active lithium was calculated based on the second standard curve. :

[0085]

[0086] The data results are shown in Table 3:

[0087] Sample number Hydrogen peak area (μV⋅s) Total volume of hydrogen (μL) <![CDATA[Total molar amount of hydrogen (mmol) 10 -3 > Mass of active lithium (mg) 1 93.5 31.58 1.291 0.01791 2 94.8 31.94 1.306 0.01812 3 94.3 31.8 1.300 0.01804 average value 94.2 31.77 1.299 0.01802

[0088] Based on the above calculations, in this embodiment, the total amount of active lithium in the lithium-supplemented electrode is... =0.01802mg.

[0089] Step S4: Assemble the lithium-added negative electrode sheets of the same specifications as in Step S3 into a half-cell for electrochemical delithiation treatment. Then, place the delithiated electrode sheets in a sealed reaction vessel and add deionized water. After the reaction is complete, extract the gas from the upper layer of the reaction vessel, inject it into a gas chromatograph for detection, record the hydrogen peak area, and then calculate the residual lithium mass of the delithiated electrode sheets based on the first and second standard curves. .

[0090] Specifically, take three lithium-added negative electrode sheets of the same specifications as those used in step S3, and assemble a half-cell in a glove box, using the lithium sheet as the counter electrode and the electrolyte as 1M LiPF6 / DMC:EC:EMC=1:1:1. Clamp the assembled coin cell onto the Blue Electric testing system: charge it at a constant current and constant voltage at a current density of 0.01-0.1C to 1.5-2.5V, preferably at 0.025C to 2.0V, for electrochemical delithiation. After delithiation, move the battery into the glove box for disassembly, remove the electrode sheets, rinse three times in DMC, and dry on a heating platform at 60°C.

[0091] The delithiated electrodes were placed into three vials, sealed, and removed from the glove box. 5 mL of deionized water was injected into each vial using a syringe, and the vials were allowed to stand for 30 min. 0.5 mL of the upper gas layer in the reaction vial was extracted using a gas-tight syringe, injected into a gas chromatograph, and the hydrogen peak area was recorded.

[0092] The hydrogen volume was calculated based on the first standard curve:

[0093]

[0094] Calculate the total volume of hydrogen produced inside the container by combining the volume of the top space of the reaction vessel:

[0095]

[0096] Convert the total volume of hydrogen to the total molar amount of hydrogen using the ideal gas law (room temperature 25℃, atmospheric pressure 101 kPa):

[0097]

[0098] The residual lithium mass was calculated based on the second standard curve. :

[0099]

[0100] The data results from this step are shown in Table 4:

[0101] Sample number Hydrogen peak area (μV⋅s) Total volume of hydrogen (μL) <![CDATA[Total molar amount of hydrogen (mmol) 10 -3 > Residual lithium mass (mg) 1 35.57 11.76 0.481 0.00667 2 38.57 12.6 0.515 0.00715 3 37.77 12.38 0.506 0.00702 average value 37.30 12.25 0.501 0.00695

[0102] In this embodiment, the residual lithium mass of the delithiation electrode =0.00695mg.

[0103] Example S5: Total active lithium mass of the lithium-filled electrode calculated according to steps S3 and S4 and the mass of residual lithium on the delithiation electrode The lithium utilization rate of the lithium-added anode was calculated using the formula. ,in:

[0104] Calculate the lithium replenishment utilization rate using the formula:

[0105]

[0106] in, To replenish the total mass of active lithium in the lithium electrode, The residual lithium mass of the delithiation electrode.

[0107] In this embodiment,

[0108] In summary, the quantitative detection method for the utilization rate of lithium-replenishing anodes based on titration-gas chromatography provided by this invention can accurately determine the total amount of active lithium and the mass of residual lithium in the lithium-replenishing anode, achieving precise quantification of lithium-replenishing utilization rate. Specifically, this invention does not use the amount of metallic lithium added before lithium-replenishing or the theoretical amount of lithium-replenishing as the total lithium content. Instead, after the lithium-replenishing anode is prepared, the active lithium in the electrode that can react with water to produce hydrogen gas is directly titrated and detected by gas chromatography. The total amount of active lithium measured is used as the total lithium content in the calculation of lithium-replenishing utilization rate. This excludes inert lithium compounds such as lithium carbonate formed by oxidation due to residual oxygen and moisture during lithium-replenishing processes such as calendering, vapor deposition, or spraying from the usable lithium content, avoiding the problem of inaccurate utilization rate evaluation caused by including inert lithium in the total lithium content in traditional methods. Secondly, the detection targets for the total active lithium in this invention include metallic lithium and lithium-containing intermediate phases such as lithium-carbon compounds and lithium-silicon compounds formed during the lithium replenishment reaction, which can react with water to generate hydrogen. This allows for the inclusion of lithium that was not completely electrochemically removed during the initial lithium removal process but still originates from the lithium replenishment process into the quantitative range, thereby reducing the evaluation bias caused by relying solely on the capacity of the initial electrochemical lithium removal. Thirdly, after electrochemical lithium removal treatment on a lithium replenishment anode of the same specification, this invention further performs the same titration-gas chromatography detection on the delithiated electrode to quantitatively obtain dead lithium and residual lithium that failed to be removed from intermediate phases such as lithium-carbon compounds and lithium-silicon compounds. The difference between the total active lithium and the residual lithium is used to characterize the actual amount of lithium utilized. Therefore, this invention can establish a quantitative closed loop from two dimensions: the total reactive active lithium after lithium replenishment and the unutilized residual lithium after lithium removal. This overcomes the shortcomings of traditional electrochemical estimation methods that cannot distinguish between inert lithium, intermediate phase lithium, and residual lithium, providing a reliable detection method for optimizing the lithium replenishment process and evaluating its effectiveness.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for quantitatively detecting the utilization rate of lithium-added anodes based on gas chromatography, characterized in that, Includes the following steps: Step S1: Establish the first standard curve of hydrogen volume versus hydrogen peak area in gas chromatography; Step S2: Place metallic lithium and deionized water in a sealed reaction vessel to generate hydrogen gas, and then establish a second standard curve of metallic lithium mass versus total molar amount of hydrogen gas. Step S3: Place the lithium-added negative electrode sheet and deionized water in a sealed reaction vessel. After the reaction is complete, extract the gas from the upper layer of the vessel and inject it into a gas chromatograph to obtain the hydrogen peak area. Then, calculate the total mass of active lithium in the lithium-added electrode sheet based on the first and second standard curves. ; Step S4: Assemble the lithium-added negative electrode into a half-cell and perform electrochemical delithiation treatment. Then, place the delithiated electrode in a sealed reaction vessel and add deionized water. After the reaction is complete, extract the gas from the upper layer of the reaction vessel and inject it into a gas chromatograph for detection. Record the hydrogen peak area, and then calculate the residual lithium mass of the delithiated electrode according to the first and second standard curves. ; Example S5: Calculating the lithium utilization rate of the lithium-added anode using a formula , To improve lithium utilization in the lithium anode, To replenish the total mass of active lithium in the lithium electrode, The residual lithium mass of the delithiation electrode.

2. The method for quantitative detection of lithium-ion anode utilization rate based on gas chromatography as described in claim 1, characterized in that, The process of establishing the second standard curve in step S2 is as follows: First, lithium metal and deionized water are placed in a sealed reaction vessel. After the reaction is complete, the gas in the upper layer of the vessel is extracted and injected into a gas chromatograph to obtain the hydrogen peak area. Then, the volume of hydrogen in the extracted gas is calculated according to the first standard curve, and the total volume of hydrogen produced in the reaction vessel is calculated by combining the volume of the space at the top of the reaction vessel. Then, the total volume of hydrogen is converted into the total molar amount of hydrogen according to the ideal gas equation, and a second standard curve is established between the mass of lithium metal and the total molar amount of hydrogen.

3. The method for quantitative detection of lithium-ion anode utilization rate based on gas chromatography as described in claim 1, characterized in that, The relationship of the first standard curve in step S1 is: Where A is the peak area of ​​hydrogen gas. Let be the volume of hydrogen gas, and a and b be fitting constants.

4. The method for quantitative detection of lithium-ion anode utilization rate based on gas chromatography as described in claim 1, characterized in that, The relationship of the second standard curve in step S2 is as follows: in, This represents the total molar amount of hydrogen gas in the reaction vessel. denoted as the mass of lithium metal, and k as a proportionality coefficient.

5. The method for quantitative detection of lithium-ion anode utilization rate based on gas chromatography as described in claim 2, characterized in that, The formula for calculating the total volume of hydrogen in the reaction vessel in step S2 is as follows: in, This represents the volume of hydrogen gas detected by gas chromatography. This refers to the volume of the space at the top of the reaction vessel. This represents the volume of gas drawn by the syringe.

6. The method for quantitative detection of lithium-ion anode utilization rate based on gas chromatography as described in claim 5, characterized in that, The volume of the top space of the reactor The calculation formula is: in, This refers to the total volume of the reaction vessel. This refers to the volume of deionized water injected.

7. The method for quantitative detection of lithium-ion anode utilization rate based on gas chromatography as described in claim 6, characterized in that, In step S3, the total molar amount and total volume of hydrogen in the reaction vessel conform to the ideal gas law, and the conversion relationship is as follows: in, This represents the total molar amount of hydrogen gas in the reaction vessel. One standard atmosphere Let T be the total volume of hydrogen, T be the Kelvin temperature, and R be the molar gas constant.

8. The method for quantitative detection of lithium-ion anode utilization rate based on gas chromatography as described in claim 5, characterized in that, The conditions for electrochemical delithiation in step S4 are as follows: the half-cell assembled with the lithium-replenishing electrode is charged to 1.5-2.5V under constant current and constant voltage at a current density of 0.01C to 0.1C.

9. The method for quantitative detection of lithium-ion anode utilization rate based on gas chromatography as described in claim 1, characterized in that, The reaction vessel is a vial.

10. The method for quantitative detection of lithium-ion anode utilization rate based on gas chromatography as described in claim 1, characterized in that, The specific operation of step S1 is to take hydrogen standard gas samples of different volumes, inject them into the gas chromatograph, and record the corresponding hydrogen peak area. Using the hydrogen volume as the abscissa and the peak area as the ordinate, a first standard curve relationship between the hydrogen volume and the gas chromatographic signal peak area is obtained by linear fitting.

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