A method and device for detecting the contents of nickel, cobalt and manganese in a nickel-cobalt composite hydroxide preparation liquid

Abstract

The application provides a detection method for the content of nickel, cobalt and manganese in a preparation liquid containing nickel-cobalt composite hydroxide, which is prepared from a nickel sulfate mother liquor, a cobalt sulfate mother liquor, a manganese sulfate mother liquor and M x A n The compensation solution mother liquor is used as a raw material to prepare standard solutions with different concentrations of nickel, cobalt, manganese and M ions to form a gradient standard solution group; the X-ray fluorescence spectrometer is used to detect each standard solution in the Alphas correction mode to obtain the correction intensity of nickel, cobalt and manganese elements, and the standard curve of nickel, cobalt and manganese is fitted according to the known concentration and the correction intensity of nickel, cobalt and manganese; and then the standard curve is used as a working curve to detect the ion concentration of nickel, cobalt and manganese in the preparation liquid by using the X-ray fluorescence spectrometer in the Alphas correction mode. The detection method has the advantages of simple operation, high efficiency, accurate detection of the preparation liquid with high concentration, non-destructive measurement of the sample, no environmental protection risk and considerable application prospect. The detection device based on the detection method is also provided.

Description

Technical Field

[0001] This invention belongs to the field of elemental detection technology, specifically relating to a method and device for detecting the content of nickel, cobalt, and manganese in the preparation solution of nickel-cobalt composite hydroxide production process using X-ray fluorescence analysis technology. Background Technology

[0002] In the field of electrode materials, the content of elements such as nickel, cobalt, manganese, and aluminum in nickel-cobalt composite hydroxide products, such as nickel-cobalt-manganese ternary hydroxides, nickel-cobalt-aluminum ternary hydroxides, and nickel-cobalt-manganese-aluminum quaternary hydroxides, is one of the important indicators for product inspection. In wet production processes, the element content of nickel, cobalt, and manganese in the nickel-cobalt composite hydroxide product needs to be controlled by adjusting the content of elements such as nickel sulfate and cobalt sulfate in the mixed salt solution used as the preparation solution. Therefore, a stable and reliable detection method is needed to analyze the content of elements such as nickel, cobalt, manganese, and aluminum to meet the requirements of the production process.

[0003] Traditionally, instruments such as ICP and AAS are mostly used to analyze the nickel, cobalt, and manganese content in nickel-cobalt composite hydroxide preparation solutions. These methods suffer from problems such as complex pretreatment, long analysis times, and demanding instrument testing conditions. Because the nickel, cobalt, and manganese content in nickel-cobalt composite hydroxide preparation solutions is very high, large dilution factors introduce significant operational, dilution, and analytical errors, resulting in relatively poor stability of the test results. Furthermore, ICP testing requires a demanding environment, necessitating regular maintenance and periodic replacement of consumables, incurring high costs to ensure normal instrument operation. In addition, ICP testing requires gradient dilution for each sample, necessitating instrument warm-up and establishment of a working curve before each test, leading to low testing efficiency. Summary of the Invention

[0004] To address the above problems, one objective of this invention is to provide a method for detecting the nickel, cobalt, and manganese content in the preparation solution of nickel-cobalt composite hydroxide production process using X-ray fluorescence analysis technology.

[0005] The applicant used a conventional sulfate standard solution as the standard solution and conducted tests using X-ray fluorescence. When preparing the working curve, it was found that the sample test results deviated significantly from the theoretical values, resulting in poor accuracy.

[0006] In view of the problems existing in the prior art and the problems discovered by the applicant, the present invention provides the following technical solution: A method for detecting the content of nickel, cobalt, and manganese in a nickel-cobalt composite hydroxide preparation solution, comprising: S1. Preparation of raw material mother liquor: Preparation of nickel sulfate mother liquor, cobalt sulfate mother liquor, manganese sulfate mother liquor and M x A n The compensation solution mother liquor; the cation M of the compensation solution mother liquorn+ The ions are one or more of potassium, calcium, scandium, titanium, vanadium, chromium, iron, copper, zinc, gallium, and germanium, and the anion A in the mother liquor of the compensation solution is... x- It is nitrate; S2. Preparation of gradient standard solution group: Using each mother liquor as raw material, prepare standard solutions with different concentrations of nickel, cobalt, manganese and M ions to form a gradient standard solution group. The difference in the total concentration of nickel, cobalt, manganese and M ions in each standard solution in the gradient standard solution group can be no greater than 3%, preferably no greater than 2%. S3. Establishing standard curves: In Alphas calibration mode, X-ray fluorescence spectrometer is used to detect each standard solution to obtain the measurement intensity and alpha correction factor of each element ion (nickel, cobalt, manganese, M and S). Further, the calibration intensity of Ni, Co and Mn ions in each standard solution is obtained. Based on the ion concentration of Ni, Co and Mn in each standard solution and the corresponding calibration intensity, standard curves of Ni, Co and Mn ions are fitted. S4. Detection of nickel, cobalt, and manganese ion concentrations in the nickel-cobalt composite hydroxide preparation solution: Using the standard curves of Ni, Co, and Mn as working curves, the nickel-cobalt composite hydroxide preparation solution was detected by X-ray fluorescence spectrometry in Alphas correction mode to obtain the correction intensities of nickel, cobalt, and manganese ions, and finally to obtain the ion concentrations of nickel, cobalt, and manganese.

[0007] In this technical solution, the nickel-cobalt composite hydroxide preparation solution refers to the reaction raw material solution prepared during the production process of nickel-cobalt composite hydroxides, such as a mixed sulfate solution containing nickel, cobalt, manganese, and aluminum. The nickel-cobalt composite hydroxides include nickel-cobalt-manganese ternary hydroxides, nickel-cobalt-aluminum ternary hydroxides, nickel-cobalt-manganese-aluminum quaternary hydroxides, and nickel-cobalt-manganese-zirconium quaternary hydroxides, etc.

[0008] Preferably, in step S3, the specific process is as follows: An energy-dispersive X-ray fluorescence spectrometer can detect the measured intensities of Ni, Co, Mn, S, and M elements in each standard solution. In Alpha correction mode, the alpha correction factor is calculated through theoretical analysis or linear regression (least squares method, etc.). Based on the alpha correction factor and the measured intensities of Ni, Co, Mn, S, and M elements, the correction intensities of Ni, Co, and Mn are automatically calculated in Alpha correction mode. Then, based on the concentrations of Ni, Co, and Mn elements and the correction intensities, standard curves for Ni, Co, and Mn are fitted. It should be noted that Alpha correction mode is a commonly used analytical mode for X-ray fluorescence spectrometers. The alpha correction factor is calculated through standard theoretical analysis or linear regression (least squares method), which is a conventional calculation. The alpha correction factor is used to calculate the intensity correction caused by inter-element effects (called matrix effects) occurring within the sample during measurement. The alpha correction factors include the alpha correction factors of Co, Mn, Ni, sulfate, and M to Ni; the alpha correction factors of Co, Mn, Ni, M, and sulfate to Mn; the alpha correction factors of Co, Mn, Ni, M, and sulfate to Co; and the alpha correction factors of Co, Mn, Ni, M, and sulfate to S. Since Ni, Co, and Mn ions already form a gradient in the preparation of standard solutions, their accurate alpha correction factors can be obtained. Furthermore, the response of iron to X-ray fluorescence signals is similar to that of nickel, cobalt, and manganese; therefore, the focus is on obtaining the accurate alpha correction factor for sulfate.

[0009] Here, M refers to the element corresponding to the cation in the compensation solution mother liquor. For example, when the compensation solution is ferric nitrate, M corresponds to Fe. In this step, the X-ray fluorescence spectrometer can obtain the measured intensity and alpha correction factor, and perform the conversion of the correction intensity for Ni, Co, and Mn elements. In actual operation, the X-ray fluorescence spectrometer is used to detect each standard solution in Alphas correction mode (a conventional correction mode). This can efficiently and automatically identify the peak position, automatically calculate the peak intensity, calculate the corresponding alpha correction factor, and finally obtain the correction intensity data for elements such as Ni, Co, and Mn.

[0010] Through in-depth research, the inventors discovered that to obtain the accurate alpha correction factor, standard solutions with different sulfate concentrations need to be prepared. However, differences in the total concentration of major metal ions in the standard solutions can easily lead to matrix interference, thus affecting the detection process. This invention addresses this by adding a nitrate compensation solution during the preparation of the standard solutions, constructing standard solutions with different sulfate concentration gradients. This facilitates a more accurate acquisition of the sulfate alpha correction factor. Furthermore, the iron ions in the ferric nitrate compensation solution ensure that the total concentration of major metal ions in the test solution remains essentially consistent, avoiding matrix interference caused by different matrix concentrations. In addition, the elemental analysis range of the X-ray fluorescence spectrometer is F-Am, and nitrate does not introduce additional matrix interference.

[0011] Because different metal ion concentrations in solution imply matrix changes, and the mass absorption coefficients of different matrices affect the response of X-ray fluorescence signals, the response of elements such as iron to X-ray fluorescence signals is similar to that of nickel, cobalt, and manganese, and their atomic weights are also similar. By keeping the total concentration of the main metal ions in the solution essentially consistent, the matrix effect in the solution is made essentially consistent, thereby significantly improving detection accuracy. The matrix refers to the components in the test solution. In this invention, the matrix mainly includes nickel, cobalt, manganese, and sulfate elements. In particular, the concentration of the main metal ions represents the matrix composition in the solution.

[0012] By adding the aforementioned nitrate and other compensating solutions during the preparation of multiple standard solutions, sulfate concentration gradients with different concentrations are formed in the standard solutions, while maintaining the total metal element concentration essentially consistent with that of other standard solutions (e.g., the difference in total ion concentration is no greater than 2%). X-ray fluorescence spectrometry can accurately calculate the alpha correction coefficients (alpha correction factors) of sulfate for nickel, cobalt, and manganese based on the sulfate matrix with different concentration gradients. Furthermore, by maintaining the total metal element concentration essentially consistent with that of other standard solutions, matrix interference is minimized, significantly improving test stability and accuracy. In addition, the elemental analysis range of the X-ray fluorescence spectrometer is F-Am, and nitrate does not introduce additional matrix interference; the preferred anion is A. x- It contains nitrate ions. Adding ferric nitrate solution can maintain a relatively consistent solution density.

[0013] Preferably, in step S1, the mother liquor of the compensation solution is ferric nitrate solution.

[0014] Preferably, in step S2, the concentration range of nickel, cobalt, and manganese ions in the gradient standard solution group covers the concentration range of nickel, cobalt, and manganese ions in the preparation solution to be tested, and at least one metal ion among nickel, cobalt, and manganese in the gradient standard solution group forms a gradient distribution between the standard solutions according to the corresponding ion concentration range of the preparation solution to be tested.

[0015] Preferably, in step S2, M is added during the preparation of multiple standard solutions. x A n A compensation solution stock solution is used to create a sulfate gradient among multiple standard solutions, while maintaining the total metal element concentration in the multiple standard solutions substantially consistent with the total metal element concentration in other standard solutions, thereby obtaining an accurate alpha correction factor for sulfate against nickel, cobalt, and manganese. The multiple standard solutions can be, for example, two or more standard solutions, three or more standard solutions, five or more standard solutions, seven or more standard solutions, etc., as long as the alpha correction factor can be accurately obtained, there is no particular limitation. In this invention, M is added during the preparation of the standard solutions. x A n The purpose of using a compensating solution stock solution, such as ferric nitrate solution, is to form different concentrations of sulfate ions in multiple standard gradient solutions, so that energy dispersive X-ray (EDX) fluorescence spectrometers can more accurately obtain the alpha correction factor of sulfate against nickel, cobalt, and manganese. Since it is only necessary to form different concentrations of sulfate and accurately obtain the alpha correction factor, it is not necessary to add ferric nitrate to each gradient standard solution.

[0016] Preferably, the total concentration of nickel, cobalt, manganese and M elements in the standard solution is 80-130 g / L, more preferably 90-130 g / L, and even more preferably 100-130 g / L.

[0017] It should be noted that the total concentration of metal elements in the preparation solution of nickel-cobalt composite hydroxides such as nickel-cobalt-manganese ternary hydroxides used in the preparation process of cathode material precursors is basically maintained at 100-140 g / L, preferably 110-130 g / L. However, the detection method and retrieval device of the present invention are not limited to this concentration range, and can be applied to preparation solutions of nickel-cobalt hydroxides with similar concentration ranges of metal elements by simple adjustments.

[0018] Preferably, in step S2, the concentration ranges of nickel, cobalt, and manganese in the gradient standard solution group are set according to the concentration ranges of nickel, cobalt, and manganese in the nickel-cobalt composite hydroxide preparation solution.

[0019] Preferably, in step S2, the concentration range of nickel in the gradient standard solution group is 40-130 g / L, the concentration range of cobalt is 0-40 g / L, the concentration range of Mn is 0-40 g / L, and the concentration range of Fe is 0-130 g / L, preferably 0 g / L-60 g / L, more preferably 0 g / L-42 g / L, and even more preferably 25 g / L-42 g / L.

[0020] Preferably, in step S1, the concentration of nickel ions in the nickel sulfate mother liquor is 80-140 g / L, more preferably 80-130 g / L, further preferably 90-130 g / L, and even more preferably 100-130 g / L; The concentration of cobalt ions in the cobalt sulfate mother liquor is 80-130 g / L, more preferably 90-130 g / L, and even more preferably 100-130 g / L; The concentration of manganese ions in the manganese sulfate mother liquor is 80-130 g / L, more preferably 90-130 g / L, and even more preferably 100-130 g / L; The concentration of cations in the mother liquor of the compensation solution is 80-130 g / L, more preferably 90-130 g / L, and even more preferably 100-130 g / L.

[0021] Preferably, in step S2, the number of standard solutions in the gradient standard solution group is 6-30, and more preferably 10-20.

[0022] Preferably, in step S2, the difference in total ion concentrations of nickel, cobalt, manganese and M among the standard solutions in the gradient standard solution group is no greater than 1.0%, more preferably no greater than 0.8%, even more preferably no greater than 0.5%, and the optimal value is 0%.

[0023] Another object of the present invention is to provide a detection device that applies the above-described detection method.

[0024] Compared with the prior art, the present invention has the following beneficial effects: This invention considers various factors such as the total concentration of metal elements and the sulfate concentration gradient, and can accurately obtain the alpha correction coefficients of nickel, cobalt, manganese, sulfate, etc. Ultimately, it pioneers a new method for rapid, accurate and efficient element detection using energy dispersive X-ray (EDX) fluorescence spectrometry. In terms of cost and efficiency, it can overturn the expensive and time-consuming mainstream detection technology in this industry, which is mainly based on ICP, and has huge industrial application prospects and commercial value.

[0025] The detection method of this invention can be applied to detect the ion content of nickel, cobalt, manganese, and aluminum in nickel-cobalt-manganese ternary hydroxides, nickel-cobalt-aluminum ternary hydroxides, and nickel-cobalt-manganese-aluminum quaternary hydroxides, which contain nickel and cobalt. The detection method of this invention is simple to operate, highly efficient, and can accurately detect high concentrations of nickel-cobalt-containing composite hydroxide preparation solutions without requiring significant dilution of the preparation solution, which is significantly superior to existing ICP elemental detection methods. It enables non-destructive measurement of samples, poses no environmental risks, and has very promising application prospects in industrial production processes. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is the standard curve for nickel in Example 1; Figure 2 This refers to the cobalt element standard curve from Example 1; Figure 3 This is the standard curve for manganese in Example 1. Detailed Implementation

[0028] The following describes the manufacturers of the raw materials and instruments used in the embodiments and comparative examples, as well as the instruments and analytical methods used in the product analysis. All raw materials or reagents used in the embodiments of this invention were purchased from mainstream manufacturers and are of analytical purity or higher. There are no particular restrictions as long as they achieve the expected effect. Where specific techniques or conditions are not specified in the embodiments of this invention, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Instruments or raw materials whose manufacturers are not specified are all conventionally available commercial products. Reagents whose manufacturers or concentrations are not specified are all conventionally obtainable analytical purity reagents. There are no particular restrictions as long as they achieve the expected effect.

[0029] The energy-dispersive X-ray (EDX) fluorescence spectrometer was purchased from Malvern Panalytical, model Epsilon4.

[0030] The basic parameters of the instruments used in the following examples and comparative examples, and the concentration ranges of Ni, Co, and Mn elements in the test solutions are shown in Tables 1 and 2: Example 1: Table 1. Basic parameters of energy-dispersive X-ray (EDX) fluorescence spectrometer Table 2. Concentration range of each metal element in the test solution in this embodiment. element Range (g / L) Ni 40~130 Co 0~40 Mn 0~40 A method for detecting the content of nickel, cobalt, and manganese in a nickel-cobalt composite hydroxide preparation solution, comprising: S1. Preparation of standard solutions (1) Preparation of raw material mother liquor Nickel sulfate mother liquor (c) Ni (≈125g / L): Weigh 279.70g of nickel sulfate hexahydrate (≥0.999g) into a 500mL beaker, add about 300mL of water, heat and stir to dissolve, and cool to room temperature. Transfer to a 500mL volumetric flask, dilute with water to the mark, and shake well.

[0031] Cobalt sulfate mother liquor (c) Co (≈120g / L): Weigh 114.45g of cobalt sulfate heptahydrate (≥0.999g) into a 500mL beaker, add about 100mL of water, heat and stir to dissolve, and cool to room temperature. Transfer to a 200mL volumetric flask, dilute with water to the mark, and shake well.

[0032] Manganese sulfate mother liquor (c) Mn (≈120g / L): Weigh 73.83g of manganese sulfate monohydrate (≥0.999g) into a 500mL beaker, add about 100mL of water, heat and stir to dissolve, and cool to room temperature. Transfer to a 200mL volumetric flask, dilute with water to the mark, and shake well.

[0033] ferric nitrate mother liquor (c) Fe (≈120g / L): Weigh 41.57g of ferric nitrate nonahydrate AR into a 500mL beaker, add about 30mL of water, heat and stir to dissolve, and cool to room temperature. Transfer to a 50mL volumetric flask, dilute with water to the mark, and shake well.

[0034] It should be noted that the concentration of metal elements in the prepared mother liquor is calculated based on the actual weight.

[0035] (2) Preparation of gradient standard solution groups The gradient standard solution set was prepared according to the following principles: The difference in total metal ion (Ni, Co, Mn, and Fe) concentration in each standard solution should not exceed 2%, and at least one (including one, two, or three) metal ions of nickel, cobalt, and manganese in each standard sample should form a gradient based on the corresponding element (ion) concentration range in the subsequent sample to be tested (e.g., the sample to be tested). The gradient standard solution was a mixed solution of nickel, cobalt, manganese, and iron, and the concentration range of nickel, cobalt, and manganese ions in the gradient standard solution set covered the concentration range of nickel, cobalt, and manganese ions in the preparation solution to be tested. Based on the precursor solution samples to be tested, the concentrations of nickel, cobalt, manganese, and iron ions in each standard solution were determined to be within the ranges of Ni: 40~120 g / L, Co: 0~40 g / L, Mn: 0~40 g / L, and Fe: 0~130 g / L. Fifteen gradient standard solutions were prepared as the gradient standard solution set.

[0036] The concentrations of each standard solution are shown in Table 3 below. Decimal points were not used; the concentrations were set to the target integer. The sum of the Ni, Co, Mn, and Fe element concentrations in each gradient standard solution was 120 g / L. In practice, it is sufficient to ensure that the total concentration difference of the total metal ions (Ni, Co, Mn, and Fe, etc.) in each standard solution is no greater than 2%. The concentration gradients of nickel, cobalt, and manganese in the standard solutions in Table 3 basically cover the concentration ranges of nickel, cobalt, and manganese in the nickel-cobalt-manganese ternary hydroxide preparation solutions for low, medium, and high nickel ternary materials.

[0037] The amount of ferric nitrate added should be such that the total concentration of nickel, cobalt, manganese and iron (in g / L) is within the range of the total concentration of metal elements in the sample. In this embodiment, the total concentration of metal elements in the prepared solution sample is in the range of 100 g / L to 130 g / L. Therefore, the concentration of iron in the standard solution containing ferric nitrate should be in the range of 0 g / L to 130 g / L, preferably 0 g / L to 60 g / L, and more preferably 0 g / L to 42 g / L.

[0038] Table 3. Elemental concentrations of Ni, Co, Mn, Fe, and sulfate in standard solutions of each gradient. Serial Number Ni (g / L) Co (g / L) Mn (g / L) Fe (g / L) Sulfate (g / L) 1 120 0 0 0 196.25 2 115 3 2 0 196.46 3 110 7 3 0 196.55 4 105 5 10 0 197.36 5 100 12 8 0 197.09 6 95 10 15 0 197.89 7 90 18 12 0 197.51 8 80 15 25 0 199.00 9 70 20 30 0 199.54 10 60 25 35 0 200.08 11 50 32 38 0 200.38 12 40 40 40 0 200.56 13 45 22 28 25 158.41 14 55 14 16 35 140.75 15 65 8 5 42 128.09 S3. Establish a standard curve: In Alpha correction mode, energy-dispersive X-ray (EDX) fluorescence spectrometry was used to detect the intensity of Ni, Co, Mn, S, and Fe in each standard solution. The EDX fluorescence spectrometer, in Alpha correction mode, calculated the alpha correction factors through theoretical analysis or linear regression (least squares method, etc.). Based on the alpha correction factors and the measured intensities of Ni, Co, Mn, S, and Fe, the corrected intensities of Ni, Co, Mn, and sulfate in each standard solution were obtained. Using the known concentrations of Ni, Co, and Mn and their corresponding corrected intensities, a standard curve for Ni, Co, and Mn was fitted with intensity as the ordinate and elemental content as the abscissa. This standard curve can then be used to detect the (corrected) intensity values ​​of the samples and convert them into content values.

[0039] In this embodiment, the intensities and alpha correction factors of Ni, Co, Mn, Fe, and S elements in each standard solution were detected using an X-ray fluorescence spectrometer. Based on the measured intensities and alpha correction factors of Ni, Co, Mn, Fe, and S elements, the correction intensities of Ni, Co, and Mn elements in each standard solution were calculated in Alphas correction mode. Since the concentrations of each element in each standard solution are known, based on the known concentrations of Ni, Co, and Mn elements and the aforementioned correction intensities (specific values ​​are shown in Table 4), a standard curve was fitted with the concentrations of Ni, Co, and Mn elements in each standard solution as the abscissa and the correction intensities of the corresponding elements in the corresponding standard solution as the ordinate. The standard curves for Ni, Co, and Mn elements are shown below. Figure 1 , 2 As shown in Figure 3, the linear relationship R of each standard curve is... 2 ≥0.999.

[0040] Table 4. Correction strength of Ni, Co, and Mn elements in each standard solution Gradient standard solutions Ni concentration (g / L) Co concentration (g / L) Mn concentration (g / L) Ni correction strength (cps) Co correction strength (cps) Mn correction intensity (cps) 1 120.70 0.00 0.00 840739 -187 49 2 116.27 2.93 1.85 804662 22266 14519 3 110.30 7.22 2.80 765180 55598 21661 4 105.70 4.80 9.51 734502 36671 71790 5 100.45 12.14 8.01 698023 93449 59044 6 95.47 9.62 14.88 661606 73557 111153 7 90.85 18.14 11.94 625689 139599 89505 8 80.64 15.07 25.10 554211 114502 188422 9 70.62 19.87 29.97 481317 151196 225179 10 60.82 23.73 33.58 411773 182119 253636 11 50.91 31.03 38.50 342484 236844 288892 12 40.74 39.15 39.88 272271 300642 297764 13 45.23 21.02 27.31 302935 160414 205968 14 55.46 14.36 14.24 372402 109653 106739 15 64.93 7.15 4.68 435575 54929 35333 The alpha factor is used to calculate the intensity correction caused by inter-element effects (called matrix effects) occurring within the sample during measurement. In this embodiment, the alpha correction factors include the alpha correction factors of Co, Fe, Mn, Ni, and sulfate on Ni; the alpha correction factors of Co, Fe, Mn, Ni, and sulfate on Mn; the alpha correction factors of Co, Fe, Mn, Ni, and sulfate on Co; and the alpha correction factors of Co, Fe, Mn, Ni, and sulfate on S. Since N is not within the detection range of the fluorescence instrument, nitrate does not have an effect and does not need to be detected or corrected.

[0041] S4. Detection of nickel, cobalt, and manganese content in the preparation solution during the production process of nickel-cobalt composite hydroxides: (1) Prepare the test sample box according to conventional methods. The sample box to be tested is made as follows: A corresponding sample box is made based on the instrument's sample injection turntable, as follows: The sample box consists of four parts: an inner cup, an outer cup, a lid, and a Mylar membrane. Place the outer cup on a table or a dedicated tool, place the Mylar membrane on top of the outer cup, and push the inner cup downwards. The hole in the center of the tool allows air to escape, preventing unevenness of the Mylar membrane. The bottom of the inner cup should be slightly lower than the bottom of the outer cup by 1mm. Check that the Mylar membrane is flat before use. The inner cup specifications are: inner diameter 28mm, outer diameter 30mm, height 30mm; the outer cup specifications are: inner diameter 31mm, outer diameter 33mm, height 29mm.

[0042] (2) Detection After the test solution is prepared, transfer 5 mL of the test solution into the sample box, cover it, and place it in the sample detection area; in the energy dispersive X-ray spectrometer (EDX instrument), the basic parameters of EDX mentioned above in this embodiment, the test concentration range, and the standard curves of Ni, Co, and Mn measured in this embodiment are selected as the working curves.

[0043] The nickel, cobalt, and manganese content of the nickel-cobalt composite hydroxide preparation solution can be obtained by energy dispersive X-ray fluorescence spectrometry. Specifically, the standard curves of Ni, Co, and Mn obtained in step S3 are used as working curves. The nickel-cobalt composite hydroxide preparation solution to be tested is detected by an EDX instrument in Alphas calibration mode, and the ion concentrations of nickel, cobalt, and manganese in the nickel-cobalt composite hydroxide preparation solution are finally obtained.

[0044] In this step, an EDX instrument is used to detect the measurement intensity of nickel, cobalt, and manganese in the nickel-cobalt composite hydroxide preparation solution. The measured intensity is automatically converted to a calibration intensity in Alphas calibration mode, and the ion concentrations of nickel, cobalt, and manganese in the preparation solution are then calculated based on the standard curve. In this step, the conversion from measured intensity to calibration intensity, and to nickel, cobalt, and manganese ion concentrations, are all performed by the EDX instrument. Specifically, the standard curves for Ni, Co, and Mn are used as the working curves, and energy-dispersive X-ray fluorescence spectrometry is used for detection in Alphas mode, allowing for rapid and direct determination of the ion concentrations of Ni, Co, and Mn in the nickel-cobalt composite hydroxide preparation solution.

[0045] Five different concentrations of nickel-cobalt composite hydroxide preparation solutions were prepared as test solutions, and the elemental concentrations are shown in Table 5.

[0046] Working curves were prepared based on the original sulfate standard solutions (i.e., without adding ferric nitrate solution during the preparation of each standard solution, only sulfate solution was used to prepare the gradient standard solutions as described above) and working curves were prepared based on the gradient standard solution group obtained by adding ferric nitrate to some of the standard solutions according to the present invention. The relative deviation (the percentage of the absolute deviation of a single measurement to the average value) was used for analysis, and the results are shown in Table 5. As can be seen from Table 5, because the standard solution group prepared in this embodiment uses ferric nitrate compensation solution, the alpha correction factor of sulfate for nickel, cobalt, and manganese is obtained more accurately, thus the measurement results are significantly improved, with relative deviations all less than or equal to 1.0%.

[0047] It should be noted that ferric nitrate is not added to the test solution. In this embodiment, the total ion concentrations of nickel, cobalt, and manganese in the actual test sample are all between (120±10) g / L. Currently, the total metal element concentration in the nickel-cobalt composite hydroxide preparation solution used in the preparation process of ternary cathode material precursors is basically in the range of 100-140 g / L, preferably in the range of 110-130 g / L, which is basically consistent with the total metal element concentration in the standard solution.

[0048] Table 5. Comparison of detection results for five nickel-cobalt composite hydroxide preparation solutions with different compositions using conventional standard curves and the standard curve prepared in this embodiment. Precision experiment: To verify the stability of the testing process of this method, the same sample box preparation operation and sampling and testing operation were repeatedly performed 10 times on the same nickel-cobalt-manganese preparation solution using the detection method of this embodiment. The stability of this method was examined from the precision of the experimental data. The test data of the nickel-cobalt-manganese preparation solution are shown in the table below. The relative standard deviation of each element is less than or equal to 1.0%, indicating that this method is accurate and reliable.

[0049] Table 6. Results of multiple tests on the same nickel-cobalt-manganese preparation solution sample using the detection method of this embodiment. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for detecting the content of nickel, cobalt, and manganese in a nickel-cobalt composite hydroxide preparation solution, characterized in that, include: S1. Preparation of raw material mother liquor: Preparation of nickel sulfate mother liquor, cobalt sulfate mother liquor, manganese sulfate mother liquor and M x A n The compensation solution mother liquor; the M x A n The mother liquor of the compensation solution is ferric nitrate solution; S2. Preparation of gradient standard solution group: Using each mother liquor as raw material, standard solutions with different concentrations of nickel, cobalt, manganese, and iron ions were prepared to form a gradient standard solution group. The total concentration of nickel, cobalt, manganese, and iron ions in each standard solution of the gradient standard solution group did not differ by more than 2%. S3. Establish a standard curve: In Alphas calibration mode, X-ray fluorescence spectrometry was used to detect each standard solution to obtain the measured intensity and alpha correction factor of each element ion. The correction intensities of nickel, cobalt and manganese were further obtained. Based on the concentration of nickel, cobalt and manganese ions in each standard solution and the corresponding correction intensities, standard curves of nickel, cobalt and manganese ions were fitted. S4. Detect the concentration of nickel, cobalt, and manganese ions in the preparation solution of nickel-cobalt composite hydroxide: Using the standard curves of nickel, cobalt, and manganese ions as working curves, the preparation solution of nickel-cobalt composite hydroxide was detected by X-ray fluorescence spectrometry in Alphas correction mode to obtain the correction intensity of nickel, cobalt, and manganese ions, and finally the ion concentrations of nickel, cobalt, and manganese.

2. The detection method as described in claim 1, characterized in that, In step S2, the concentration range of nickel, cobalt, and manganese ions in the gradient standard solution group covers the concentration range of nickel, cobalt, and manganese ions in the preparation solution to be tested, and at least one metal ion among nickel, cobalt, and manganese in the gradient standard solution group forms a gradient distribution among the standard solutions.

3. The detection method as described in claim 1, characterized in that, In step S2, the ferric nitrate compensation solution mother liquor is added during the preparation of multiple standard solutions to form a sulfate gradient, and the total concentration of metal elements in the multiple standard solutions is kept basically consistent with the total concentration of metal elements in other standard solutions, thereby obtaining the alpha correction factor of sulfate for nickel, cobalt and manganese.

4. The detection method as described in claim 1, characterized in that, The total concentration of nickel, cobalt, manganese and iron in each standard solution is 80-130 g / L, and the total concentration of metal elements in the nickel-cobalt composite hydroxide preparation solution is 100-140 g / L.

5. The detection method as described in claim 1, characterized in that, In step S2, the concentration ranges of nickel, cobalt, and manganese in the gradient standard solution group are set according to the concentration ranges of nickel, cobalt, and manganese in the nickel-cobalt composite hydroxide preparation solution.

6. The detection method as described in claim 1, characterized in that, In step S2, the concentration range of nickel in the gradient standard solution group is 40-130 g / L, the concentration range of cobalt is 0-40 g / L, the concentration range of Mn is 0-40 g / L, and the concentration range of Fe is 0-130 g / L.

7. The detection method as described in claim 1, characterized in that, In step S1, the concentration of nickel ions in the nickel sulfate mother liquor is 80-130 g / L; The concentration of cobalt ions in the cobalt sulfate mother liquor is 80-130 g / L; The concentration of manganese ions in the manganese sulfate mother liquor is 80-130 g / L; The concentration of cations in the mother liquor of the compensation solution is 80-130 g / L.

8. The detection method as described in claim 1, characterized in that, In step S2, the number of standard solutions in the gradient standard solution group is 6-30, and the difference in the total ion concentration of nickel, cobalt, manganese and iron in each standard solution is no greater than 1.0%.

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