Method for measuring content of inorganic carbon in positive electrode material additive by using carbon and sulfur analyzer, and use of method

Abstract

The present disclosure provides a method for measuring the content of inorganic carbon in a positive electrode material additive by using a carbon and sulfur analyzer, and a use of the method. The method comprises the following steps: (1) mixing a positive electrode material additive and a solvent, dissolving the mixture to obtain a suspension, and carrying out solid-liquid separation to obtain an insoluble substance to be measured; and (2) using a carbon and sulfur analyzer to measure the content of carbon in said insoluble substance, and calculating the content of inorganic carbon in the positive electrode material additive according to the following formula. According to the present disclosure, a positive electrode material additive and a solvent are fully dissolved and mixed, and a solid-liquid separation method is used to realize separation of inorganic carbon and organic carbon in the positive electrode material additive, and then the content of carbon in an insoluble substance is measured, and the content of inorganic carbon in the positive electrode material additive is calculated. The measurement method has accurate result, small fluctuation, and good development potential.

Description

A method for determining the inorganic carbon content in positive electrode material additives using a carbon-sulfur analyzer and its application Technical Field

[0001] The present invention relates to the field of analytical chemistry, and in particular to a method for determining the inorganic carbon content in a cathode material additive using a carbon-sulfur analyzer and its application. Background Art

[0002] In recent years, with the rapid development of new energy vehicles, higher requirements have been continuously placed on the performance of lithium-ion batteries. Among them, the improvement of battery energy density is the most urgent. Lithium-ion battery lithium replenishment technology is an important means to improve battery energy density.

[0003] By adding lithium-supplementing materials to the positive electrode of lithium-ion batteries, the materials decompose and release active lithium during charging, compensating for the irreversible loss of active lithium caused by SEI growth at the negative electrode. Positive electrode lithium-supplementing materials offer advantages such as relatively stable chemical properties, ease of synthesis, low cost, and high lithium-supplementing capacity. Furthermore, the positive electrode lithium-supplementing process is well compatible with existing lithium-ion battery manufacturing processes, providing a new solution for the commercial application of lithium-supplementing technology. Therefore, the ability to accurately measure the inorganic and organic carbon content in positive electrode material additives is of great significance to the research and development of positive electrode material additives.

[0004] The carbon content test of the carbon sulfur analyzer is usually used to test the total carbon content of the material. However, when the additive material contains organic carbon substances, the inorganic carbon content cannot be obtained by direct testing using the carbon sulfur analyzer.

[0005] Therefore, there is an urgent need to design a method to solve the problem of accurately determining the inorganic carbon content in positive electrode material additives using a carbon-sulfur analyzer.

[0006] Summary of the Invention

[0007] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0008] In response to the shortcomings of the prior art, the present invention aims to provide a method for determining the inorganic carbon content in a cathode material additive using a carbon-sulfur analyzer and its application. The present invention achieves this by fully dissolving and mixing the cathode material additive with a solvent, separating the inorganic carbon from the organic carbon in the cathode material additive using solid-liquid separation, and then calculating the inorganic carbon content in the cathode material additive by measuring the carbon content of the insoluble matter. This method provides accurate results with minimal fluctuations and has great development potential.

[0009] To achieve this goal, the present disclosure adopts the following technical solutions:

[0010] In a first aspect, the present disclosure provides a method for determining the inorganic carbon content in a positive electrode material additive using a carbon-sulfur analyzer, the method comprising the following steps:

[0011] (1) mixing the positive electrode material additive and the solvent, dissolving them to obtain a suspension, and obtaining the insoluble matter to be tested after solid-liquid separation;

[0012] (2) Using a carbon-sulfur analyzer to measure the carbon content in the insoluble matter to be measured, and calculating the content of inorganic carbon in the positive electrode material additive according to the following formula 1:

[0013] Wherein, Δm is the mass of the insoluble matter to be measured, in g; ω is the carbon content in the insoluble matter to be measured, in %; m is the mass of the positive electrode material additive, in g; ω c It is the content of inorganic carbon in the positive electrode material additive, in %.

[0014] The present invention discloses a method of separating inorganic carbon from organic carbon in the positive electrode material additive by fully dissolving and mixing the positive electrode material additive and the solvent, and then calculating the inorganic carbon content in the positive electrode material additive by testing the carbon content of the insoluble matter. The determination method has accurate results and small fluctuations, and has good development potential.

[0015] As an optional technical solution of the present disclosure, the positive electrode material additive in step (1) includes inorganic carbon substances and organic carbon substances.

[0016] The determination method provided by the present disclosure can accurately test the content of inorganic carbon substances in positive electrode material additives containing inorganic carbon substances and organic carbon substances.

[0017] In one embodiment, the inorganic carbon material includes any one of carbon black, conductive graphite, carbon nanotubes, or nanofibers, or a combination of at least two thereof.

[0018] In one embodiment, the organic carbon material includes any one of Li2DHBN, Li2C2O4, Li2C4O4 or Li2CO3, or a combination of at least two thereof.

[0019] In one embodiment, the solvent in step (1) comprises water.

[0020] In the present disclosure, water is used as a solvent to mix with the positive electrode material additive, so that the positive electrode material additive can be dissolved, laying a foundation for separating inorganic carbon from organic carbon.

[0021] In one embodiment, the solid-liquid ratio of the positive electrode material additive and the solvent in step (1) is (1-2) g: (250-500) mL, wherein the selection range of the positive electrode material additive "(1-2) g" can be, for example, 1 g, 1.5 g or 2 g, and the selection range of the solvent "(250-500) mL" can be, for example, 250 mL, 350 mL, 450 mL or 500 mL, etc.

[0022] It should be noted that the solid-to-liquid ratio of the positive electrode material additive and the solvent refers to the ratio of the mass of the positive electrode material additive to the volume of the solvent.

[0023] In the present disclosure, if the solid-liquid ratio of the positive electrode material additive and the solvent is too small, the mass of inorganic carbon after filtration is too small, resulting in a larger constant weight weighing error and a larger test error; if the solid-liquid ratio of the positive electrode material additive and the solvent is too large, the organic carbon substance in the additive cannot be fully dissolved, resulting in a larger test result.

[0024] As an optional technical solution of the present disclosure, the mixing process in step (1) is accompanied by stirring.

[0025] In the present disclosure, stirring is performed during the mixing process in step (1) to help fully dissolve the positive electrode material additive.

[0026] In one embodiment, the stirring rate is 500-700 rpm, for example, 500 rpm, 550 rpm, 600 rpm, 650 rpm or 700 rpm, and the stirring time is 25-50 min, for example, 25 min, 30 min, 35 min, 40 min, 45 min or 50 min, etc.

[0027] In the present disclosure, the above-mentioned specific stirring rate and stirring time can ensure that the positive electrode material additives are evenly dispersed and fully dissolved. If the stirring time is too short, the organic carbon will not be fully dissolved in water, resulting in high test results and large deviations.

[0028] As an optional technical solution of the present disclosure, the solid-liquid separation method in step (1) includes suction filtration.

[0029] In the present disclosure, the insoluble matter can be effectively separated by filtration.

[0030] In one embodiment, in the filtration method, the filtration device used is a sand core crucible-vacuum filtration device.

[0031] In one embodiment, the sand core crucible-vacuum filtration device is a G4 sand core crucible-vacuum filtration device.

[0032] In the present disclosure, a sand core crucible-vacuum filtration device is used as a filtration device, which can make the final measurement result more accurate and less volatile.

[0033] As an optional technical solution of the present disclosure, a flushing step is further performed after the solid-liquid separation in step (1), and the flushing agent used in the flushing includes water.

[0034] In the present disclosure, water is used to rinse the separated insoluble matter, which helps to fully rinse and filter the organic carbon matter in the additive material.

[0035] As an optional technical solution of the present disclosure, before using the carbon-sulfur analyzer in step (2) to determine the carbon content in the insoluble matter to be measured, the carbon-sulfur analyzer is first calibrated for carbon content testing.

[0036] The purpose of calibrating the carbon content test of the carbon-sulfur instrument disclosed in this disclosure is to ensure that the instrument test results are accurate and stable.

[0037] As an optional technical solution of the present disclosure, the specific steps of the carbon content test calibration include:

[0038] (a) mixing a standard substance and a flux, performing an oxidation reaction to obtain an intermediate product containing CO, CO2, and SO2, and then loading the intermediate product into a catalytic furnace to perform a catalytic reaction under the action of a catalyst to obtain a mixed product containing CO2, SO2, and SO3;

[0039] (b) After the mixed product is loaded into a desulfurization reagent tube, it is introduced into a carbon detection cell to determine the carbon content.

[0040] In the present disclosure, the standard substance undergoes an oxidation reaction, so that the carbon in the standard substance is oxidized into CO2 and CO; the mixed gas containing CO2, CO and SO2 enters the heated catalyst furnace together, and undergoes catalytic conversion CO→CO2 in the catalyst furnace. After this mixed gas is loaded into the desulfurization reagent tube, it is introduced into the carbon detection cell to measure the carbon.

[0041] As an optional technical solution of the present disclosure, the method includes the following steps:

[0042] (I) Place the cathode material additive in a container and record its mass as m;

[0043] (II) adding water to the container and performing magnetic stirring at a rate of 500-700 rpm for 25-50 min to completely dissolve the positive electrode material additive to obtain a suspension;

[0044] Wherein, the solid-liquid ratio of the positive electrode material additive and the solvent is (1-2) g: (250-500) mL;

[0045] (III) Clean the sand core crucible-vacuum filtration device, dry it, and weigh it, recording its mass as m1;

[0046] (IV) filtering the suspension using the sand core crucible-vacuum filtration device treated in step (III) to obtain insoluble matter, then rinsing the insoluble matter several times with water, and then repeatedly rinsing and filtering the insoluble matter to obtain the insoluble matter to be tested;

[0047] (V) Clean, dry, and weigh the sand core crucible containing the insoluble material to be measured, and record its mass as m2;

[0048] (VI) Carry out carbon content test calibration, the specific steps include:

[0049] The standard substance and the flux are mixed and subjected to oxidation reaction to obtain an intermediate product containing CO, CO2 and SO2, and then the intermediate product is loaded into a catalytic furnace and subjected to catalytic reaction under the action of a catalyst to obtain a mixed product containing CO2, SO2 and SO3;

[0050] After the mixed product is loaded into a desulfurization reagent tube, it is introduced into a carbon detection cell to measure the carbon content;

[0051] (VII) After calibration of the standard sample, a certain amount of the insoluble matter to be measured is weighed into a crucible and its carbon content is determined as ω;

[0052] (VIII) Calculate the content of inorganic carbon in the positive electrode material additive according to the following formula 1:

[0053] Wherein, Δm=m2-m1, is the mass of the insoluble matter to be measured, in g; ω is the carbon content in the insoluble matter to be measured, in %; m is the mass of the positive electrode material additive, in g; ω c It is the content of inorganic carbon in the positive electrode material additive, in %.

[0054] It should be noted that the present disclosure does not limit the time for repeated rinsing and filtration of insoluble matter, and the process stops until the insoluble matter is completely rinsed.

[0055] The present disclosure adopts the above-mentioned determination method to accurately determine the content of inorganic carbon in the positive electrode material additive, and the determination result has small fluctuation and small variance.

[0056] In a second aspect, the present disclosure provides an application of the method described in the first aspect, wherein the method is applied to determine the content of inorganic carbon in a positive electrode material additive for a lithium battery.

[0057] The method provided in the present disclosure is used to determine the content of inorganic carbon in positive electrode material additives for lithium batteries, which is of great significance to the research and development of positive electrode material additives.

[0058] The numerical range described in the present disclosure includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present disclosure no longer exhaustively lists the specific point values ​​included in the range.

[0059] Compared with the prior art, the present disclosure has the following beneficial effects:

[0060] The present invention discloses a method of separating inorganic carbon from organic carbon in the positive electrode material additive by fully dissolving and mixing the positive electrode material additive and the solvent, and then calculating the inorganic carbon content in the positive electrode material additive by testing the carbon content of the insoluble matter. The determination method has accurate results and small fluctuations, and has good development potential.

[0061] Still other aspects will become apparent upon reading and understanding the detailed description. DETAILED DESCRIPTION

[0062] The technical solution of the present disclosure is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only used to help understand the present disclosure and should not be regarded as specific limitations of the present disclosure.

[0063] Example 1

[0064] This embodiment provides a method for determining the inorganic carbon content in a positive electrode material additive using a carbon-sulfur analyzer, the method comprising the following steps:

[0065] (1) Place 2 g of cathode material additive in a 500 mL beaker and record its mass as m.

[0066] Among them, the cathode material additive is a mixture of carbon black and Li2C2O4;

[0067] (2) Add 500 mL of water to the beaker, place a magnetic rod, cover with a watch glass, and perform magnetic stirring at a rate of 600 rpm for 30 min to completely dissolve the positive electrode material additive to obtain a suspension;

[0068] Among them, the solid-liquid ratio of the positive electrode material additive and water is 2g:500mL;

[0069] (3) Clean, dry and weigh the G4 sand core crucible-vacuum filtration device, and record its mass as m1;

[0070] (4) using the sand core crucible-vacuum filtration device treated in step (3) to filter the suspension to obtain insoluble matter, then rinse the insoluble matter with water several times, and then repeatedly rinse and filter the insoluble matter until 400 mL of water is consumed, thereby obtaining the insoluble matter to be tested;

[0071] (5) Clean, dry and weigh the G4 sand core crucible containing the insoluble material to be measured, and record its mass as m2;

[0072] (6) Carry out carbon content test calibration, the specific steps include:

[0073] 0.10±0.02g of the standard substance and flux are mixed and subjected to an oxidation reaction to oxidize carbon into CO2 and CO. The mixed gas containing CO2, CO, and SO2 is then introduced into a heated catalyst furnace, where CO is catalytically converted into CO2. The resulting mixed gas containing CO2, SO2, and SO3 is then loaded into a desulfurization reagent tube and finally introduced into a carbon detection cell to determine the carbon content.

[0074] The standard material is coke (machine code 95-011), and the flux is a mixture of pure Sn, pure Fe and pure W (ω C <0.0005%), the catalyst is platinum-coated silica gel;

[0075] (7) After the standard sample is calibrated, weigh 0.02 g of the insoluble matter to be measured into a crucible and determine its carbon content as ω;

[0076] (8) Calculate the content of inorganic carbon in the positive electrode material additive according to the following formula 1:

[0077] Wherein, Δm=m2-m1 is the mass of the insoluble matter to be measured, in g; ω is the carbon content in the insoluble matter to be measured, in %; m is the mass of the positive electrode material additive, in g; ω c It is the content of inorganic carbon in the positive electrode material additive, in %.

[0078] Example 2

[0079] This embodiment provides a method for determining the inorganic carbon content in a positive electrode material additive using a carbon-sulfur analyzer, the method comprising the following steps:

[0080] (1) Place 1g of cathode material additive in a 500mL beaker and record its mass as m;

[0081] Among them, the cathode material additives are carbon black and Li2C2O4;

[0082] (2) Add 500 mL of water to the beaker, place a magnetic rod, cover with a watch glass, and perform magnetic stirring at a rate of 600 rpm for 25 min until the positive electrode material additive is completely dissolved to obtain a suspension;

[0083] Among them, the solid-liquid ratio of the positive electrode material additive and water is 1g:500mL;

[0084] (3) Clean, dry and weigh the G4 sand core crucible-vacuum filtration device, and record its mass as m1;

[0085] (4) using the sand core crucible-vacuum filtration device treated in step (3) to filter the suspension to obtain insoluble matter, then rinse the insoluble matter with water several times, and then repeatedly rinse and filter the insoluble matter until 400 mL of water is consumed, thereby obtaining the insoluble matter to be tested;

[0086] (5) Clean, dry and weigh the G4 sand core crucible containing the insoluble material to be measured, and record its mass as m2;

[0087] (6) Carry out carbon content test calibration, the specific steps include:

[0088] 0.10±0.02g of the standard substance and flux are mixed and subjected to an oxidation reaction to oxidize carbon into CO2 and CO. The mixed gas containing CO2, CO, and SO2 is then introduced into a heated catalyst furnace, where CO is catalytically converted into CO2. The resulting mixed gas containing CO2, SO2, and SO3 is then loaded into a desulfurization reagent tube and finally introduced into a carbon detection cell to determine the carbon content.

[0089] The standard material is coke (machine code 95-011), and the flux is a mixture of pure Sn, pure Fe and pure W (ω C <0.0005%), the catalyst is platinum-coated silica gel;

[0090] (7) After the standard sample is calibrated, weigh 0.02 g of the insoluble matter to be measured into a crucible and determine its carbon content as ω;

[0091] (8) Calculate the content of inorganic carbon in the positive electrode material additive according to the following formula 1:

[0092] Wherein, Δm=m2-m1 is the mass of the insoluble matter to be measured, in g; ω is the carbon content in the insoluble matter to be measured, in %; m is the mass of the positive electrode material additive, in g; ω c It is the content of inorganic carbon in the positive electrode material additive, in %.

[0093] Example 3

[0094] This embodiment provides a method for determining the inorganic carbon content in a positive electrode material additive using a carbon-sulfur analyzer, the method comprising the following steps:

[0095] (1) Place 2 g of cathode material additive in a 500 mL beaker and record its mass as m.

[0096] Among them, the cathode material additives are carbon black and Li2C2O4;

[0097] (2) Add 250 mL of water to the beaker, place a magnetic rod, cover with a watch glass, and perform magnetic stirring at a rate of 600 rpm for 50 min to completely dissolve the positive electrode material additive to obtain a suspension;

[0098] Among them, the solid-liquid ratio of the positive electrode material additive and water is 2g:250mL;

[0099] (3) Clean, dry and weigh the G4 sand core crucible-vacuum filtration device, and record its mass as m1;

[0100] (4) using the sand core crucible-vacuum filtration device treated in step (3) to filter the suspension to obtain insoluble matter, then rinse the insoluble matter with water several times, and then repeatedly rinse and filter the insoluble matter until 400 mL of water is consumed, thereby obtaining the insoluble matter to be tested;

[0101] (5) Clean, dry and weigh the G4 sand core crucible containing the insoluble material to be measured, and record its mass as m2;

[0102] (6) Carry out carbon content test calibration, the specific steps include:

[0103] 0.10±0.02g of the standard substance and flux are mixed and subjected to an oxidation reaction to oxidize carbon into CO2 and CO. The mixed gas containing CO2, CO, and SO2 is then introduced into a heated catalyst furnace, where CO is catalytically converted into CO2. The resulting mixed gas containing CO2, SO2, and SO3 is then loaded into a desulfurization reagent tube and finally introduced into a carbon detection cell to determine the carbon content.

[0104] The standard material is coke (machine code 95-011), and the flux is a mixture of pure Sn, pure Fe and pure W (ω C <0.0005%), the catalyst is platinum-coated silica gel;

[0105] (7) After the standard sample is calibrated, weigh 0.02 g of the insoluble matter to be measured into a crucible and determine its carbon content as ω;

[0106] (8) Calculate the content of inorganic carbon in the positive electrode material additive according to the following formula 1:

[0107] Wherein, Δm=m2-m1 is the mass of the insoluble matter to be measured, in g; ω is the carbon content in the insoluble matter to be measured, in %; m is the mass of the positive electrode material additive, in g; ω c It is the content of inorganic carbon in the positive electrode material additive, in %.

[0108] Example 4

[0109] The difference between this embodiment and embodiment 1 is that the G4 sand core crucible-vacuum filtration device in step (3) is replaced by a filter membrane-vacuum filtration device.

[0110] The remaining methods and parameters remained the same as in Example 1.

[0111] Example 5

[0112] The difference between this embodiment and embodiment 1 is that the amount of water added in step (2) is 200 mL, so that the solid-liquid ratio of the positive electrode material additive and water is 2 g:200 mL.

[0113] The remaining methods and parameters remained the same as in Example 1.

[0114] Example 6

[0115] The difference between this embodiment and embodiment 1 is that the stirring time in step (2) is 20 minutes.

[0116] The remaining methods and parameters remained the same as in Example 1.

[0117] Performance Testing

[0118] (1) The content of inorganic carbon in the positive electrode material additive was determined using the method provided in the above examples, and each example was measured twice. The measurement results are shown in Table 1.

[0119] Table 1

[0120] analyze:

[0121] As can be seen from the above table, Example 4 uses a filter membrane-vacuum filtration device for filtration. Since the inorganic carbon of the insoluble matter is easily attached to the wall, the measurement result will be low and the error is large; Example 5 uses the method of adding 200mL of solvent water and stirring for 20min in Example 6, both of which will make the organic carbon insufficiently dissolved in water, resulting in a high test result and a large deviation. In the present disclosure, a crucible-vacuum filtration device is used, and sufficient solvent is added to fully dissolve, which can achieve almost complete separation of inorganic carbon and organic carbon, and accurately measure the carbon content using a carbon-sulfur meter, thereby accurately calculating the content of inorganic carbon.

[0122] (2) Six samples were taken in parallel and the inorganic carbon content was determined according to the determination method of Example 1. The determination results are shown in Table 2.

[0123] Table 2

[0124] analyze:

[0125] As can be seen from the above table, the average value of the inorganic carbon content in the positive electrode material additive detected by the method provided by the present disclosure is 14.96%, and the relative standard deviation of the detection result is 0.56%, indicating that the method has good precision.

[0126] (3) 2 g of the sample was taken, and then 0.25 g and 0.5 g of pure Ketjen black were added respectively to obtain the first sample and the second sample. The inorganic carbon content was then determined according to the determination method provided in Example 1. The results are shown in Table 3.

[0127] Table 3

[0128] analyze:

[0129] As can be seen from the above table, the recovery rate is in the range of 98.6-103.1%, which meets the range specified by the national standard, indicating that this method has high accuracy in testing the inorganic carbon content in the positive electrode material additive.

[0130] (IV) The carbon content of two standard products (YSBC37660-12 and JIZI 95-012) was determined according to the method provided in Example 1. The results are shown in Table 4.

[0131] Table 4

[0132] analyze:

[0133] As can be seen from the above table, the test results of the method provided by the present disclosure are in good consistency with the results of the standard, indicating that this method is feasible for determining the carbon content.

Claims

1. A method for determining the inorganic carbon content in the additive of the cathode material by a carbon-sulfur analyzer, comprising the following steps: (1) Mix the additive of the cathode material and a solvent, dissolve them to obtain a suspension, and obtain the insoluble matter to be measured after solid-liquid separation; (2) Use a carbon-sulfur analyzer to measure the carbon content in the insoluble matter to be tested, and calculate the content of inorganic carbon in the positive electrode material additive according to the following formula (1): Among them, Δm is the mass of the insoluble matter to be measured, with the unit of g; ω is the carbon content in the insoluble matter to be measured, with the unit of %; m is the mass of the additive of the positive electrode material, with the unit of g; ω c is the content of inorganic carbon in the additive of the positive electrode material, with the unit of %.

2. The method according to claim 1, wherein The additive of the cathode material in step (1) includes inorganic carbon substances and organic carbon substances.

3. The method according to claim 1 or 2, wherein The solvent in step (1) includes water.

4. The method according to any one of claims 1-3, wherein The solid-liquid ratio of the additive of the cathode material to the solvent in step (1) is (1 - 2) g : (250 - 500) mL.

5. The method according to any one of claims 1-4, wherein, Stirring is accompanied during the mixing process in step (1); Optionally, the stirring rate is 500 - 700 rpm, and the stirring time is 25 - 50 min.

6. The method according to any one of claims 1-5, wherein The method of solid-liquid separation in step (1) includes the suction filtration method.

7. The method according to claim 6, wherein, In the suction filtration method, the suction filtration device used is a sintered crucible - vacuum suction filtration device.

8. The method according to any one of claims 1-7, wherein, After the solid-liquid separation in step (1), a rinsing step is also carried out. The rinsing agent used during rinsing includes water.

9. The method according to any one of claims 1-8, wherein, Before measuring the carbon content in the insoluble matter to be measured by the carbon-sulfur analyzer described in step (2), the carbon-sulfur analyzer is calibrated for carbon content measurement first.

10. The method according to claim 9, wherein, The specific steps of the carbon content measurement calibration include: (a) Mix a standard substance and a fluxing agent, carry out an oxidation reaction to obtain an intermediate product containing CO, CO2 and SO2, and then load the intermediate product into a catalytic furnace to carry out a catalytic reaction under the action of a catalyst to obtain a mixed product containing CO2, SO2 and SO3; (b) After loading the mixed product into a desulfurization reagent tube, introduce it into a carbon detection cell to measure the carbon content.

11. According to the method according to any one of claims 1-10, wherein, The method includes the following steps: (Ⅰ) Place the additive of the cathode material in a container, and record its mass as m; (Ⅱ) Add water to the container and carry out magnetic stirring. The stirring rate is 500 - 700 pm, and the stirring time is 25 - 50 min to completely dissolve the additive of the cathode material to obtain a suspension; Among them, the solid-liquid ratio of the additive of the cathode material to the solvent is (1 - 2) g : (250 - 500) mL; (Ⅲ) Wash and dry the sintered crucible - vacuum suction filtration device and weigh it, record its mass as m1; (Ⅳ) Use the sintered crucible - vacuum suction filtration device processed in step (Ⅲ) to carry out suction filtration on the suspension to obtain insoluble matter, then use water to rinse the insoluble matter several times until clean, and then repeat rinsing and suction filtration on the insoluble matter to obtain the insoluble matter to be measured; (Ⅴ) Wash and dry the sintered crucible containing the insoluble matter to be measured and weigh it, record its mass as m2; (Ⅵ) Carry out carbon content measurement calibration. The specific steps include: Mix a standard substance and a fluxing agent, carry out an oxidation reaction to obtain an intermediate product containing CO, CO2 and SO2, and then load the intermediate product into a catalytic furnace to carry out a catalytic reaction under the action of a catalyst to obtain a mixed product containing CO2, SO2 and SO3; After loading the mixed product into a desulfurization reagent tube, introduce it into a carbon detection cell to measure the carbon content; (Ⅶ) After calibrating the standard sample, weigh a certain amount of the insoluble matter to be measured in a crucible and measure its carbon content as ω; (Ⅷ) Calculate the content of inorganic carbon in the additive of the positive electrode material according to the following formula 1: Among them, Δm = m2 - m1, which is the mass of the insoluble substance to be measured, with the unit of g; ω is the carbon content in the insoluble substance to be measured, with the unit of %; m is the mass of the additive of the positive electrode material, with the unit of g; ω c is the content of inorganic carbon in the additive of the positive electrode material, with the unit of %.

12. An application of the method according to any one of claims 1 - 11 in determining the inorganic carbon content in the additive of the lithium battery cathode material.

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