Pretreatment method and detection method for detecting content of boron element in fluorine-containing positive electrode material

Abstract

The invention provides a pretreatment method and a detection method for detecting the content of a boron element in a fluorine-containing positive electrode material. The pretreatment method comprises the following steps: mixing a fluorine-containing positive electrode material with phosphoric acid, and then adding a digestion agent for digestion to obtain a digestion product; and mixing the digestion product with perchloric acid, and carrying out fluorine removal treatment to obtain a sample to be detected. In the pretreatment method developed by the invention, the principle that phosphoric acid reacts with hydrofluoric acid to generate a stable fluorine-containing compound is firstly utilized, so that the phenomenon that the boron content test is relatively low due to the fact that fluorine and boron in the fluorine-containing positive electrode material generate volatile BF3 is avoided, and the content test accuracy of the boron element is effectively improved; secondly, the digestion product is treated by perchloric acid, so that trace free fluorine ions in the solution can be completely discharged, the trace fluorine ions are prevented from corroding testing equipment in the testing process, and the service life is prolonged. The boron content detection based on the pretreatment method is rapid and convenient to operate, and has a good development prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical detection, and specifically relates to a pretreatment method and a detection method for detecting the content of boron element in a fluorine-containing positive electrode material. Background Art

[0002] Lithium-ion batteries have been widely used in portable electronic products, electric vehicles and military communications due to their high specific energy, good cycle performance and low self-discharge. The positive electrode material is an important component of lithium-ion batteries and the source of life for batteries. It has an important impact on the performance and cost of lithium-ion batteries. At present, the main positive electrode materials for lithium batteries are lithium cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, etc. These materials have their own advantages and disadvantages. In order to obtain positive electrode materials with excellent performance, the materials are modified and studied. The main means are bulk ion doping of the materials and coating on the surface of the materials. Among them, bulk ion doping of positive electrode materials is to dope metal cations during the preparation of positive electrode materials to improve the electronic conductivity of the materials or increase the lithium ion migration rate; the common method of coating the materials is to coat the surface of the materials with metal oxides or carbon materials, which plays a role in improving the surface conductivity of the materials, preventing the electrolyte from corroding the electrode materials and inhibiting the lattice collapse. Doping F and B ions in the bulk phase of the material or fluoriding and boriding the surface of the material is also an effective means to improve the electrochemical properties of the material. Fluorine and boron have high electronegativity and high free energy, and their use in lithium-ion battery positive electrode materials can improve the energy density and cycle stability of the material.

[0003] The amount of B element introduced by doping or coating has a great influence on the performance of the material. Therefore, accurate and efficient determination of the content of B element doped or coated in the positive electrode material is very important for the research and development and production of positive electrode materials. The industry usually uses inductively coupled plasma emission spectrometer (ICP) to determine the content of B element in the sample. Sample preparation is required before the determination. In the sample preparation method of the prior art, the positive electrode material is usually dissolved in an acidic solution to obtain a better dissolution effect. However, because the sample contains fluorine, hydrofluoric acid will be formed after acid addition. After heating, hydrofluoric acid is easy to react with B to generate volatile BF3, which affects the measurement results and is difficult to accurately measure.

[0004] Therefore, there is an urgent need to develop a non-volatile, fast and easy-to-operate pretreatment method for fluorine-containing cathode materials to accurately detect the content of boron in fluorine-containing cathode materials, which plays an important guiding role in the research and development and production of fluorine-containing cathode materials. Summary of the invention

[0005] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a pretreatment method and a detection method for detecting the content of boron in a fluorine-containing positive electrode material. In the pretreatment method developed by the present invention, firstly, the principle of phosphoric acid and hydrofluoric acid reacting to generate a stable fluorine-containing compound is used, thereby avoiding the phenomenon that the fluorine and boron in the fluorine-containing positive electrode material generate volatile BF3, which leads to a low boron content test, and effectively improves the accuracy of the boron content test; secondly, the digestion product is treated with perchloric acid to exhaust the trace free fluorine ions in the solution, avoid the trace fluorine ions from corroding the test equipment during the test, and extend the service life. Boron content detection based on this pretreatment method is fast and easy to operate, and has good development prospects.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a pretreatment method for detecting the boron content in a fluorine-containing positive electrode material, the pretreatment method comprising the following steps:

[0008] The fluorine-containing positive electrode material and phosphoric acid are mixed, and then a digestion agent is added for digestion to obtain a digestion product.

[0009] The digestion product is mixed with perchloric acid and subjected to fluorine removal treatment to obtain a sample to be tested.

[0010] In the pretreatment method developed by the present invention, the principle of phosphoric acid and hydrofluoric acid reacting to generate stable fluorine-containing compounds (such as phosphoric acid fluoride) is firstly used, thereby avoiding the phenomenon that the fluorine in the fluorine-containing positive electrode material generates volatile BF3 with boron, resulting in a low boron content test, and effectively improving the accuracy of the boron content test; secondly, the digestion product is treated with perchloric acid to exhaust the trace free fluorine ions in the solution, avoiding the trace fluorine ions from corroding the test equipment during the test, and extending the service life. Boron content detection based on this pretreatment method is fast and easy to operate, and has good development prospects.

[0011] It should be noted that the boiling point of perchloric acid is higher than that of HF, HCl and HNO3, so it can eliminate the trace free fluoride ions in the digestion product and avoid the corrosion of the test equipment by the trace fluoride ions during the test.

[0012] And / or, the concentration of the phosphoric acid is 75-90wt%, for example, 75wt%, 80wt%, 85wt% or 90wt%.

[0013] In the present invention, phosphoric acid of appropriate concentration helps to better dissolve the fluorine-containing positive electrode material and fully react.

[0014] Preferably, the mass volume ratio of the fluorine-containing cathode material and phosphoric acid is (0.2-0.5) g:(1-3) mL. Exemplarily, the mass selection range of the fluorine-containing cathode material "(0.2-0.5) g" can be, for example, 0.2 g, 0.3 g, 0.4 g or 0.5 g, etc., and the volume selection range of the phosphoric acid "(1-3) mL" can be, for example, 1 mL, 1.5 mL, 2 mL, 2.5 mL or 3 mL, etc.

[0015] In the present invention, the use of a suitable mass volume ratio of the fluorine-containing positive electrode material and phosphoric acid is helpful to more effectively wet the fluorine-containing positive electrode material.

[0016] Preferably, the fluorine-containing positive electrode material is a fluorine-boron-containing positive electrode material or a fluorine-containing but boron-free positive electrode material.

[0017] It should be noted that when the fluorine-containing positive electrode material is a fluorine-free positive electrode material, it can be prepared by mixing a fluorine-containing material (for example, a ternary material doped with aluminum fluoride) and a boron source (for example, boric acid).

[0018] Preferably, when the fluorine-containing positive electrode material is a fluorine-boron-containing positive electrode material, the mixing method comprises:

[0019] Phosphoric acid is added to the fluorine-boron-containing positive electrode material to wet the fluorine-boron-containing positive electrode material.

[0020] Preferably, the digestion agent includes any one of hydrochloric acid, nitric acid or hydrogen peroxide, or a combination of at least two of them.

[0021] It should be noted that the present invention does not limit the concentration of hydrochloric acid, and illustratively, it can be 36 wt %, etc. The present invention does not limit the concentration of nitric acid, and illustratively, it can be 68 wt %, etc.

[0022] Preferably, the digestion temperature is 120-220°C, for example, it can be 120°C, 140°C, 160°C, 180°C, 190°C, 200°C or 220°C.

[0023] Preferably, the concentration of the perchloric acid is 65-75 wt%, for example, 65 wt%, 70 wt% or 75 wt%.

[0024] In the present invention, an appropriate concentration of perchloric acid is helpful to achieve sufficient fluoride removal.

[0025] Preferably, the volume ratio of the digestion product to perchloric acid is 1:(1-2), for example, it can be 1:1, 1:1.5 or 1:2.

[0026] In the present invention, an appropriate amount of perchloric acid added can more effectively remove fluorine.

[0027] Preferably, the temperature of the defluorination treatment is 200-220°C, for example, 200°C, 210°C or 220°C.

[0028] In the present invention, at 200-220° C., perchloric acid can be made to smoke, indicating that trace amounts of free fluoride ions in the solution have been exhausted.

[0029] Preferably, the pre-treatment method comprises the following steps:

[0030] (1) Phosphoric acid with a concentration of 75-90 wt % is added to the fluorine-boron-containing positive electrode material to wet the fluorine-boron-containing positive electrode material, and then a digestion agent is added to digest the material at 120-220° C. to obtain a digestion product after the digestion is complete.

[0031] Among them, the mass volume ratio of the fluorine-boron positive electrode material and phosphoric acid is (0.2-0.5) g: (1-3) mL.

[0032] (2) The digestion product is mixed with perchloric acid having a concentration of 65-75 wt %, and subjected to fluorine removal treatment at 200-220° C., followed by cooling and constant volume to obtain a sample to be tested.

[0033] Wherein, the volume ratio of the digestion product to perchloric acid is 1:(1-2).

[0034] In the present invention, the sample to be tested obtained after the pretreatment method described in the first aspect can be directly used in the detection process of the boron content. The present invention does not specifically limit the specific detection method, and the present invention is applicable to all methods for detecting the boron content in the positive electrode material.

[0035] In a second aspect, the present invention provides a method for detecting the boron content in a fluorine-containing positive electrode material, the detection method comprising the following steps:

[0036] The fluorine-containing positive electrode material is subjected to the pretreatment method as described in the first aspect to obtain a sample to be tested.

[0037] The boron content of the sample to be tested is tested.

[0038] Preferably, the test method for the boron content includes an ICP test method, and the steps of the ICP test method include:

[0039] A boron standard curve is established using a boron standard solution, and then the sample to be tested is tested. The content of boron in the sample to be tested is calculated based on the spectral signal of the sample to be tested and the standard curve, and the average value is taken after multiple tests.

[0040] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] In the detection method developed by the present invention, firstly, the principle of phosphoric acid and hydrofluoric acid reacting to generate stable fluorine-containing compounds is used, thereby avoiding the phenomenon that the fluorine in the fluorine-containing positive electrode material generates volatile BF3 with boron, resulting in a low boron content test, and effectively improving the accuracy of the boron content test; secondly, the digestion product is treated with perchloric acid to exhaust the trace free fluorine ions in the solution, avoiding the trace fluorine ions from corroding the test equipment during the test, and extending the service life. The detection method is fast and easy to operate, and has good development prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The figure is a boron element spectrum diagram of a boron standard solution provided in a specific embodiment of the present invention.

[0044] Figure 2 This is a boron fitting curve provided in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0046] Example 1

[0047] This embodiment provides a pretreatment method for detecting the boron content in a fluorine-containing positive electrode material, the pretreatment method comprising the following steps:

[0048] (1) Weigh 0.4 g of fluorine-containing positive electrode material (i.e., ternary material doped with aluminum fluoride) into a polytetrafluoroethylene beaker, weigh 0.005 g of boric acid and add it into the polytetrafluoroethylene beaker to obtain a fluorine-containing boron positive electrode material.

[0049] (2) In a polytetrafluoroethylene beaker, 1 mL of 85 wt% phosphoric acid was added for soaking, and then 7.5 mL of 36 wt% hydrochloric acid and 2.5 mL of 68 wt% nitric acid were added. The polytetrafluoroethylene beaker was then placed on an electric furnace and heated to 150° C. for digestion. After the digestion was complete, a digestion product was obtained, and the volume of the digestion product was about 5 mL.

[0050] Among them, the mass volume ratio of the fluorine-containing positive electrode material and phosphoric acid is 0.405g:1mL.

[0051] (3) Add 5 mL of 70 wt% perchloric acid into the polytetrafluoroethylene beaker containing the digestion product, heat to 220°C to make the perchloric acid smoke, perform fluorine removal treatment for 5 minutes, then remove the polytetrafluoroethylene beaker, cool to room temperature (i.e., 25°C), and then use ultrapure water to make the volume into a 100 mL volumetric flask, shake well, and obtain the sample to be tested.

[0052] Wherein, the volume ratio of the digestion product to perchloric acid is 1:1.

[0053] Example 2

[0054] This embodiment provides a pretreatment method for detecting the boron content in a fluorine-containing positive electrode material, the pretreatment method comprising the following steps:

[0055] (1) Weigh 0.4 g of fluorine-containing positive electrode material (i.e., ternary material doped with aluminum fluoride) into a polytetrafluoroethylene beaker, weigh 0.007 g of boric acid and add it into the polytetrafluoroethylene beaker to obtain a fluorine-containing boron positive electrode material.

[0056] (2) In a polytetrafluoroethylene beaker, 1 mL of 85 wt% phosphoric acid was added for soaking, and then 7.5 mL of 36 wt% hydrochloric acid and 2.5 mL of 68 wt% nitric acid were added. The polytetrafluoroethylene beaker was then placed on an electric furnace and heated to 150° C. for digestion. After the digestion was complete, a digestion product was obtained, and the volume of the digestion product was about 5 mL.

[0057] Among them, the mass volume ratio of the fluorine-containing positive electrode material and phosphoric acid is 0.407g:1mL.

[0058] (3) Add 5 mL of 70 wt% perchloric acid into the polytetrafluoroethylene beaker containing the digestion product, heat to 220°C to make the perchloric acid smoke, perform fluorine removal treatment for 5 minutes, then remove the polytetrafluoroethylene beaker, cool to room temperature, and then use ultrapure water to make the volume into a 100 mL volumetric flask, shake well, and obtain the sample to be tested.

[0059] Wherein, the volume ratio of the digestion product to perchloric acid is 1:1.

[0060] Example 3

[0061] This embodiment provides a pretreatment method for detecting the boron content in a fluorine-containing positive electrode material, the pretreatment method comprising the following steps:

[0062] (1) Weigh 0.4 g of fluorine-containing positive electrode material (i.e., ternary material doped with aluminum fluoride) into a polytetrafluoroethylene beaker, weigh 0.01 g of boric acid and add it into the polytetrafluoroethylene beaker to dissolve the fluorine-containing positive electrode material.

[0063] (2) In a polytetrafluoroethylene beaker, 1 mL of 85 wt% phosphoric acid was added for soaking, and then 7.5 mL of 36 wt% hydrochloric acid and 2.5 mL of 68 wt% nitric acid were added. The polytetrafluoroethylene beaker was then placed on an electric furnace and heated to 150° C. for digestion. After the digestion was complete, a digestion product was obtained, and the volume of the digestion product was about 5 mL.

[0064] Among them, the mass volume ratio of the fluorine-containing positive electrode material and phosphoric acid is 0.41g:1mL.

[0065] (3) Add 5 mL of 70 wt% perchloric acid into the polytetrafluoroethylene beaker containing the digestion product, heat to 220°C to make the perchloric acid smoke, perform fluorine removal treatment for 5 minutes, then remove the polytetrafluoroethylene beaker, cool to room temperature, and then use ultrapure water to make the volume into a 100 mL volumetric flask, shake well, and obtain the sample to be tested.

[0066] Wherein, the volume ratio of the digestion product to perchloric acid is 1:1.

[0067] Example 4

[0068] This embodiment provides a pretreatment method for detecting the boron content in a fluorine-containing positive electrode material, the pretreatment method comprising the following steps:

[0069] (1) Weigh 0.4 g of fluorine-containing positive electrode material (i.e., ternary material doped with aluminum fluoride) into a polytetrafluoroethylene beaker, weigh 0.005 g of boric acid and add it into the polytetrafluoroethylene beaker to obtain a fluorine-containing boron positive electrode material.

[0070] (2) In a polytetrafluoroethylene beaker, 3 mL of 75 wt% phosphoric acid was added for soaking, and then 7.5 mL of 36 wt% hydrochloric acid and 2.5 mL of 68 wt% nitric acid were added. The polytetrafluoroethylene beaker was then placed on an electric furnace and heated to 150° C. for digestion. After the digestion was complete, a digestion product was obtained, and the volume of the digestion product was about 5 mL.

[0071] Among them, the mass volume ratio of the fluorine-containing positive electrode material and phosphoric acid is 0.405g:3mL.

[0072] (3) Add 5 mL of 65 wt% perchloric acid into the polytetrafluoroethylene beaker containing the digestion product, heat to 220°C to make the perchloric acid smoke, perform fluorine removal treatment for 5 minutes, then remove the polytetrafluoroethylene beaker, cool to room temperature, and then use ultrapure water to make the volume into a 250 mL volumetric flask, shake well, and obtain the sample to be tested.

[0073] Wherein, the volume ratio of the digestion product to perchloric acid is 1:1.

[0074] Example 5

[0075] This embodiment provides a pretreatment method for detecting the boron content in a fluorine-containing positive electrode material, the pretreatment method comprising the following steps:

[0076] (1) Weigh 0.4 g of fluorine-containing positive electrode material (i.e., ternary material doped with aluminum fluoride) into a polytetrafluoroethylene beaker, weigh 0.005 g of boric acid and add it into the polytetrafluoroethylene beaker to obtain a fluorine-containing boron positive electrode material.

[0077] (2) In a polytetrafluoroethylene beaker, 1 mL of 90 wt% phosphoric acid was added for soaking, and then 7.5 mL of 36 wt% hydrochloric acid and 2.5 mL of 68 wt% nitric acid were added. The polytetrafluoroethylene beaker was then placed on an electric furnace and heated to 150° C. for digestion. After the digestion was complete, a digestion product was obtained, and the volume of the digestion product was about 5 mL.

[0078] Among them, the mass volume ratio of the fluorine-containing positive electrode material and phosphoric acid is 0.405g:1mL.

[0079] (3) Add 5 mL of 75 wt% perchloric acid into the polytetrafluoroethylene beaker containing the digestion product, heat to 220°C to make the perchloric acid smoke, perform fluorine removal treatment for 5 minutes, then remove the polytetrafluoroethylene beaker, cool to room temperature, and then use ultrapure water to make the volume into a 100 mL volumetric flask, shake well, and obtain the sample to be tested.

[0080] Wherein, the volume ratio of the digestion product to perchloric acid is 1:1.

[0081] Example 6

[0082] The difference between this embodiment and embodiment 1 is that the concentration of the phosphoric acid is 70 wt %.

[0083] The remaining detection methods and parameters were consistent with those in Example 1.

[0084] Example 7

[0085] The difference between this embodiment and embodiment 1 is that the mass volume ratio of the fluorine-containing positive electrode material and phosphoric acid is 0.2 g:4 mL.

[0086] The remaining detection methods and parameters were consistent with those in Example 1.

[0087] Example 8

[0088] The difference between this embodiment and embodiment 1 is that the mass volume ratio of the fluorine-containing positive electrode material and phosphoric acid is 0.5 g:0.5 mL.

[0089] The remaining detection methods and parameters were consistent with those in Example 1.

[0090] Example 9

[0091] The difference between this embodiment and embodiment 1 is that the digestion temperature in step (2) is 95°C.

[0092] The remaining detection methods and parameters were consistent with those in Example 1.

[0093] Example 10

[0094] The difference between this embodiment and embodiment 1 is that the digestion temperature in step (2) is 230°C.

[0095] The remaining detection methods and parameters were consistent with those in Example 1.

[0096] Embodiment 11

[0097] The difference between this embodiment and embodiment 1 is that the concentration of the perchloric acid is 60 wt %.

[0098] The remaining detection methods and parameters were consistent with those in Example 1.

[0099] Comparative Example 1

[0100] The difference between this comparative example and Example 1 is that phosphoric acid is not added in step (2), and perchloric acid is not added in step (3).

[0101] The remaining detection methods and parameters were consistent with those in Example 1.

[0102] Comparative Example 2

[0103] The difference between this comparative example and Example 2 is that phosphoric acid is not added in step (2), and perchloric acid is not added in step (3).

[0104] The remaining detection methods and parameters were consistent with those in Example 2.

[0105] Comparative Example 3

[0106] The difference between this comparative example and Example 3 is that phosphoric acid is not added in step (2), and perchloric acid is not added in step (3).

[0107] The remaining detection methods and parameters were consistent with those in Example 3.

[0108] Comparative Example 4

[0109] The difference between this comparative example and Example 1 is that phosphoric acid in step (2) is replaced by acetic acid.

[0110] The remaining detection methods and parameters were consistent with those in Example 1.

[0111] Comparative Example 5

[0112] The difference between this comparative example and Example 1 is that no perchloric acid is added in step (3).

[0113] The remaining detection methods and parameters were consistent with those in Example 1.

[0114] Performance Testing

[0115] The boron content of the samples provided in the above embodiments and comparative examples was tested by ICP test method, and the specific steps included:

[0116] After setting the ICP parameters, a boron standard curve was established using boron standard solutions (including 0.0 mg / L, 0.5 mg / L, 1.0 mg / L, 5.0 mg / L, 10.0 mg / L and 20.0 mg / L). First, different concentrations of boron standard solutions were used to establish the following: Figure 1 The boron element spectrum diagram is then based on Figure 1 Get as Figure 2 The working curve shown, that is, after the linearity reaches above 0.999, the sample to be tested is measured, and the instrument calculates the content of boron in the sample to be tested based on the spectral signal of the sample to be tested and the standard curve, and the average value of the two measurements is taken.

[0117] Then the boron recovery rate is calculated, and the calculation method is: boron recovery rate = average content of boron element in the sample to be tested / theoretical content of boron in the fluorine-containing positive electrode material × 100%. The test results are shown in Table 1.

[0118] Table 1

[0119]

[0120]

[0121] analyze:

[0122] In the pretreatment method developed by the present invention, firstly, the principle of phosphoric acid and hydrofluoric acid reacting to generate stable fluorine-containing compounds is used, thereby avoiding the phenomenon that the fluorine in the fluorine-containing positive electrode material generates volatile BF3 with boron, resulting in a low boron content test, and effectively improving the accuracy of the boron content test; secondly, the digestion product is treated with perchloric acid to exhaust the trace free fluorine ions in the solution, avoiding the corrosion of the test equipment by the trace fluorine ions during the test, and extending the service life. Boron content detection based on this pretreatment is fast and easy to operate, and has good development prospects.

[0123] From the comparison between Example 1 and Example 6, it can be seen that if the concentration of phosphoric acid is too low, the fluorine element in the fluorine-containing positive electrode material cannot react completely, thereby affecting the accuracy of boron determination and causing the boron test to be low.

[0124] By comparing Example 1 with Examples 7-8, it can be seen that if the mass-to-volume ratio of the fluorine-containing positive electrode material and phosphoric acid is too low, the phosphoric acid concentration in the solution will be too high, the solution will be viscous, affecting ICP sampling and failing to fully atomize; if the mass-to-volume ratio of the fluorine-containing positive electrode material and phosphoric acid is too high, the phosphoric acid will not be able to completely wet the sample, and the phosphoric acid and hydrofluoric acid will not fully react.

[0125] By comparing Example 1 with Examples 9-10, it can be seen that if the digestion temperature in step (2) is too low, the sample will be incompletely digested and the digestion time will be long, and it will be necessary to add high acid at the end to drive out the fluorine for digestion; if the digestion temperature in step (2) is too high, it will cause a violent reaction and sample splashing.

[0126] By comparing Example 1 with Example 11, it can be seen that if the concentration of perchloric acid is too low, white smoke will not appear, and it will be impossible to identify whether the fluorine removal is completed.

[0127] By comparing Examples 1-3 with Comparative Examples 1-3, it can be seen that if phosphoric acid is not added in step (2) and perchloric acid is not added in step (3), the boron element test result will be seriously low and the Al / Si / Na in the sample will be abnormally high (the material of the central tube of the ICP injection system is SiO2, and the material of the nebulizer and the torch tube is quartz).

[0128] By comparing Example 1 with Comparative Example 4, it can be seen that if phosphoric acid is replaced by acetic acid in step (2), B in the material will react with HF to generate volatile BF3, which will seriously lead to a low boron element test.

[0129] By comparing Example 1 with Comparative Example 5, it can be seen that if perchloric acid is not added in step (3), the Al / Si / Na in the sample will be higher (the material of the central tube of the ICP injection system is SiO2, and the material of the nebulizer and torch tube is quartz).

[0130] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A pretreatment method for detecting the boron content in a fluorine-containing positive electrode material, characterized in that: The pre-treatment method comprises the following steps: The fluorine-containing cathode material and phosphoric acid are mixed, and then a digestion agent is added to perform digestion to obtain a digestion product; The digestion product is mixed with perchloric acid and subjected to fluorine removal treatment to obtain a sample to be tested.

2. The pre-treatment method according to claim 1, characterized in that: The concentration of the phosphoric acid is 75-90 wt %.

3. The pre-treatment method according to claim 1 or 2, characterized in that: The mass volume ratio of the fluorine-containing positive electrode material and phosphoric acid is (0.2-0.5) g: (1-3) mL.

4. The pre-treatment method according to any one of claims 1 to 3, characterized in that: The fluorine-containing positive electrode material is a fluorine-boron-containing positive electrode material or a fluorine-containing but boron-free positive electrode material; And / or, when the fluorine-containing positive electrode material is a fluorine-boron-containing positive electrode material, the mixing method includes: Phosphoric acid is added to the fluorine-boron-containing positive electrode material to wet the fluorine-boron-containing positive electrode material.

5. The pre-treatment method according to any one of claims 1 to 4, characterized in that: The digester includes any one of hydrochloric acid, nitric acid or hydrogen peroxide or a combination of at least two thereof; And / or, the digestion temperature is 120-220°C.

6. The pre-treatment method according to any one of claims 1 to 5, characterized in that: The concentration of the perchloric acid is 65-75 wt %.

7. The pre-treatment method according to any one of claims 1 to 6, characterized in that: The volume ratio of the digestion product to perchloric acid is 1:(1-2).

8. The pre-treatment method according to any one of claims 1 to 7, characterized in that: The temperature of the defluorination treatment is 200-220°C.

9. A method for detecting the content of boron in a fluorine-containing positive electrode material, characterized in that: The detection method comprises the following steps: Subjecting the fluorine-containing cathode material to the pretreatment method according to any one of claims 1 to 8 to obtain a sample to be tested; The boron content of the sample to be tested is tested.

10. The detection method according to claim 9, characterized in that: The testing method for the boron content includes an ICP testing method, and the steps of the ICP testing method include: A boron standard curve is established using a boron standard solution, and then the sample to be tested is tested. The content of boron in the sample to be tested is calculated based on the spectral signal of the sample to be tested and the standard curve, and the average value is taken after multiple tests.

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