CN115266688A - Method for detecting manganese elution amount in lithium iron manganese phosphate positive electrode material - Google Patents

Abstract

The invention provides a method for detecting the manganese elution amount in a lithium iron manganese phosphate anode material, which comprises the steps of preparing a certain Mn standard solution, carrying out emission light intensity test on Mn elements by using an inductively coupled plasma atomic emission spectrometer, and establishing a standard curve; and preparing a sample solution to be detected and a blank sample solution by using a water-treated lithium manganese iron phosphate anode material sample and combining a certain treatment process, performing Mn element emission intensity test on the sample solution to be detected and the blank sample solution by using an inductively coupled plasma atomic emission spectrometer, and finally calculating the concentration of Mn element in the sample solution to be detected by using a computer and combining a standard curve, thereby obtaining the manganese elution amount in the lithium manganese iron phosphate anode material. The detection method provided by the invention can be used for measuring the content of dissolved manganese in the lithium iron manganese phosphate cathode material, and has the advantages of high accuracy, simplicity, easiness in operation and detection period.

Description

A detection method for manganese dissolution in lithium manganese iron phosphate cathode material

technical field

The invention relates to the field of lithium ion batteries, in particular to a method for detecting the dissolution amount of manganese in lithium iron manganese phosphate positive electrode materials.

Background technique

Lithium iron manganese phosphate and lithium iron phosphate both have an olivine structure with a theoretical capacity of 170mAh/g, so lithium iron manganese phosphate also has the advantages of high safety and high capacity; however, the working voltage of lithium iron manganese phosphate can reach 4.10 V(vsLi ⁺ /Li), while the working voltage of lithium iron phosphate is only 3.2V(vs Li ⁺ /Li), therefore, the energy density of lithium iron manganese phosphate can be increased by about 20% compared with that of lithium iron phosphate .

However, as the ratio of manganese to iron in lithium manganese iron phosphate increases, a large number of defects and voids will appear in the material. Manganese and iron cannot completely form a unified solid solution, and a large number of defects and pores are likely to prolong the lithium ion deintercalation and Embedding, in the process of battery cycle use, seriously affects the battery cycle life of lithium manganese iron phosphate. The manganese released from this solid solution can be characterized by manganese dissolution. The lower the manganese dissolution content (up to the ppm level), the better the performance of the lithium iron phosphate lithium cathode material. Therefore, the detection of manganese dissolution of lithium manganese iron phosphate cathode material can effectively evaluate the performance of lithium manganese iron phosphate.

Since lithium manganese iron phosphate is not widely used in the production and manufacture of lithium-ion batteries, there is no public detection method for the detection of manganese dissolution by lithium manganese iron phosphate. If the content of manganese dissolution is too high, it will seriously affect the electrical properties of lithium iron manganese phosphate, so it is urgent to develop a detection method for manganese dissolution in lithium iron manganese phosphate cathode materials.

Contents of the invention

In view of this, the object of the present invention is to provide a method for detecting the dissolution amount of manganese in lithium iron manganese phosphate cathode material. The detection method provided by the invention can detect the dissolved manganese content in the lithium iron manganese phosphate positive electrode material with high accuracy, and the detection method is simple, easy to operate, and detects a period of time.

The invention provides a method for detecting the dissolution amount of manganese in lithium iron manganese phosphate cathode material, comprising the following steps:

a) Take 10.00mL of Mn element standard solution with a concentration of 1000μg/mL in a 100mL volumetric flask, add 2.00mL of concentrated hydrochloric acid, add water to make up to the mark, shake well, and obtain a reserve standard with a Mn element concentration of 100.00μg/mL solution;

b) Take 0mL, 0.50mL, 1.00mL, and 2.00mL of the stock standard solution respectively and place them in four 100mL volumetric flasks, add 2.00mL of concentrated hydrochloric acid, add water to make up to the mark, shake well, and obtain the concentration of Mn element respectively A series of standard solutions of 0μg/mL, 0.50μg/mL, 1.00μg/mL, 2.00μg/mL;

c) Utilize an inductively coupled plasma atomic emission spectrometer to respectively test the emitted light intensity of the Mn element in the series of quasi-solutions; then, take the concentration of the Mn element in the series of quasi-solutions as the abscissa, and the corresponding emitted light intensity as the ordinate , to draw a standard curve;

d) Utilize the inductively coupled plasma atomic emission spectrometer to test the emission intensity of the Mn element in the sample solution to be tested and the blank sample solution respectively, and automatically calculate the concentration of the Mn element in the sample solution to be tested by the computer from the standard curve, which is Dissolution of manganese in lithium manganese iron phosphate cathode material;

in,

In the step d), the sample solution to be tested is obtained by the following method:

S1. Take 5.00g ± 0.05g of lithium manganese iron phosphate positive electrode material and 100mL of water in a beaker, stir and mix to obtain a mixed solution;

S2, then heat the mixed solution at 25°C for 2 hours to obtain a heat preservation solution;

S3. Suction-filtering the heat preservation solution with a microporous filter membrane with a pore size of 0.45 μm, and the obtained filtrate is the sample solution to be tested;

In the step d), the preparation of the blank sample solution is carried out according to the above steps S1-S3, the difference is that the lithium manganese iron phosphate cathode material is not added in the step S1.

Preferably, in the step c), the test conditions for testing the emitted light intensity of the Mn element by using an inductively coupled plasma atomic emission spectrometer are:

Wavelength: 257.610nm;

Plasma flow: 12L/min;

Auxiliary gas flow: 1.0L/min;

Atomizer flow rate: 0.7L/min;

RF power: 1200W;

Sample flow rate: 0.5L/min;

Measuring time: 5s;

Number of repetitions: 3 times;

Observation direction: radial.

Preferably, in the step d), the test conditions for testing the emitted light intensity of the Mn element by using an inductively coupled plasma atomic emission spectrometer are:

Wavelength: 257.610nm;

Plasma flow: 12L/min;

Auxiliary gas flow: 1.0L/min;

Atomizer flow rate: 0.7L/min;

RF power: 1200W;

Sample flow rate: 0.5L/min;

Measuring time: 5s;

Number of repetitions: 3 times;

Observation direction: radial.

Preferably, in the step c), the linear correlation coefficient of the standard curve is greater than 0.9995.

Preferably, in the step a), the purity of the concentrated hydrochloric acid is superior grade.

Preferably, in the step b), the purity of the concentrated hydrochloric acid is superior grade.

Preferably, in the step S1, the accuracy of weighing the lithium iron manganese phosphate positive electrode material is 0.01 g.

Preferably, in the step S1, the lithium manganese iron phosphate positive electrode material is dried lithium manganese iron phosphate positive electrode material.

Preferably, the drying temperature is 110° C. and the drying time is 2 hours.

Preferably, in the step S2, the temperature of the heat preservation is 25° C., and the time is 2 hours;

The model of the inductively coupled plasma atomic emission spectrometer is Agilent 5110.

In the detection method provided by the present invention, a certain Mn standard solution is prepared, and an inductively coupled plasma atomic emission spectrometer is used to test the emitted light intensity of the Mn element, and a standard curve is established; moreover, a certain amount of treatment is combined with water treatment of the lithium manganese iron phosphate cathode material sample The process prepares the test sample solution and the blank sample solution, and then uses the inductively coupled plasma atomic emission spectrometer to test the emission intensity of the Mn element in the test sample solution and the blank sample solution, and finally uses the computer combined with the standard curve to calculate the concentration of the test sample solution. The concentration of the Mn element, thereby obtaining the amount of manganese dissolved in the lithium iron manganese phosphate positive electrode material. The detection method provided by the invention is simple, easy to operate and safe, can quickly detect the dissolved content of Mn, improves the working efficiency of the detection of manganese dissolution, and fills the lack of detection methods for the dissolution of manganese in lithium iron manganese phosphate cathode materials in the industry . Moreover, the present invention has a low manganese dissolution content in lithium iron manganese phosphate, which is at the ppm level. In addition, the present invention uses an inductively coupled plasma atomic emission spectrometer to detect the dissolution of manganese, which is less affected by the sample matrix, so the reference sample does not need to be strictly matched with the matrix. Therefore this method has good accuracy.

Experimental results show that the relative standard deviation of the detection method of the present invention is only 0.41%, and the detection accuracy of Mn dissolution is relatively high.

Detailed ways

The invention provides a method for detecting the dissolution amount of manganese in lithium iron manganese phosphate cathode material, comprising the following steps:

a) Take 10.00mL of Mn element standard solution with a concentration of 1000μg/mL in a 100mL volumetric flask, add 2.00mL of concentrated hydrochloric acid, add water to make up to the mark, shake well, and obtain a reserve standard with a Mn element concentration of 100.00μg/mL solution;

b) Take 0mL, 0.50mL, 1.00mL, and 2.00mL of the stock standard solution respectively and place them in four 100mL volumetric flasks, add 2.00mL of concentrated hydrochloric acid, add water to make up to the mark, shake well, and obtain the concentration of Mn element respectively A series of standard solutions of 0μg/mL, 0.50μg/mL, 1.00μg/mL, 2.00μg/mL;

c) Utilize an inductively coupled plasma atomic emission spectrometer to respectively test the emitted light intensity of the Mn element in the series of quasi-solutions; then, take the concentration of the Mn element in the series of quasi-solutions as the abscissa, and the corresponding emitted light intensity as the ordinate , to draw a standard curve;

d) Utilize the inductively coupled plasma atomic emission spectrometer to test the emission intensity of the Mn element in the sample solution to be tested and the blank sample solution respectively, and automatically calculate the concentration of the Mn element in the sample solution to be tested by the computer from the standard curve, which is Dissolution of manganese in lithium manganese iron phosphate cathode material;

in,

In the step d), the sample solution to be tested is obtained by the following method:

S1. Take 5.00g ± 0.05g of lithium manganese iron phosphate positive electrode material and 100mL of water in a beaker, stir and mix to obtain a mixed solution;

S2, then heat the mixed solution at 25°C for 2 hours to obtain a heat preservation solution;

S3. Suction-filtering the heat preservation solution with a microporous filter membrane with a pore size of 0.45 μm, and the obtained filtrate is the sample solution to be tested;

In the step d), the preparation of the blank sample solution is carried out according to the above steps S1-S3, the difference is that the lithium manganese iron phosphate cathode material is not added in the step S1.

In the detection method provided by the present invention, a certain Mn standard solution is prepared and an inductively coupled plasma atomic emission spectrometer is used to test the emitted light intensity of the Mn element to establish a standard curve; moreover, the solution to be tested is prepared by using water treatment in combination with a certain treatment process and The blank sample solution, and then use the inductively coupled plasma atomic emission spectrometer to test the emission intensity of the Mn element in the sample solution and the blank sample solution, and finally use the computer combined with the standard curve to calculate the concentration of the Mn element in the sample solution to be tested, thereby obtaining Dissolution of manganese in lithium manganese iron phosphate cathode material. The detection method provided by the invention is simple, easy to operate and safe, can quickly detect the dissolved content of Mn, and improves the working efficiency of detecting the dissolved manganese. Moreover, the present invention uses an inductively coupled plasma atomic emission spectrometer to detect Mn dissolution, the plasma light source has good atomization, excitation and ionization capabilities, and the detection method has a good detection limit, which is generally 0.1ng/mL ~100ng/mL, and the present invention has a relatively low manganese dissolution content in lithium iron manganese phosphate, specifically up to ppm level. In addition, the present invention uses an inductively coupled plasma atomic emission spectrometer to detect the dissolution of manganese, which is less affected by the sample matrix, so the reference sample does not need to be strictly matched with the matrix. Therefore this method has good accuracy.

In the detection method provided by the present invention, a standard curve is first established through steps a) to c).

[About step a]:

a) Take 10.00mL of Mn element standard solution with a concentration of 1000μg/mL in a 100mL volumetric flask, add 2.00mL of concentrated hydrochloric acid, add water to make up to the mark, shake well, and obtain a reserve standard with a Mn element concentration of 100.00μg/mL solution.

In the present invention, the concentration of the Mn element standard solution is 1000 μg/mL, which is a national certified standard sample, and the national number is GSB04-1736-2004. In the present invention, the concentrated hydrochloric acid is preferably high-grade pure concentrated hydrochloric acid, and its source is not particularly limited, as long as it is a commercial product with a concentration of 36%-38%. In the present invention, the water is preferably pure water.

In the present invention, first measure 10.00mL Mn element standard solution and place it in a 100mL volumetric flask, then add a small amount of concentrated hydrochloric acid 2.00mL, then add water to make up the volume, after adding all the above materials, shake well. The temperature condition of the above overall operation is not particularly limited, it can be carried out at room temperature, specifically 20°C. After the above treatment, a stock standard solution with a Mn element concentration of 100.00 μg/mL was prepared.

[About step b]:

b) Take 0mL, 0.50mL, 1.00mL, and 2.00mL of the stock standard solution respectively and place them in four 100mL volumetric flasks, add 2.00mL of concentrated hydrochloric acid, add water to make up to the mark, shake well, and obtain the concentration of Mn element respectively It is a series of standard solutions of 0μg/mL, 0.50μg/mL, 1.00μg/mL and 2.00μg/mL.

Step b) of the present invention is to use the stock standard solution obtained in step a) to prepare a series of standard solutions with different concentrations. Specifically, measure the stock standard solution 0mL, 0.50mL, 1.00mL, and 2.00mL respectively and place them in four 100mL volumetric flasks, then add 2.00mL of concentrated hydrochloric acid to these four volumetric flasks, and then add Add water to the bottle to make up to the mark. Wherein, the concentrated hydrochloric acid is preferably high-grade pure concentrated hydrochloric acid, and its source is not particularly limited, and it can be a commercial product with a concentration of 36%-38%. The water is preferably pure water. After adding all the above ingredients, shake well. The temperature condition of the above overall operation is not particularly limited, it can be carried out at room temperature, specifically 20°C. After the above treatment, a series of standard solutions with concentrations of Mn element of 0 μg/mL, 0.50 μg/mL, 1.00 μg/mL and 2.00 μg/mL were prepared.

[About step c]:

c) Utilize an inductively coupled plasma atomic emission spectrometer to respectively test the emitted light intensity of the Mn element in the series of quasi-solutions; then, take the concentration of the Mn element in the series of quasi-solutions as the abscissa, and the corresponding emitted light intensity as the ordinate , to draw a standard curve.

In the present invention, after the series of standard solutions are obtained in step b), the emitted light intensity of the Mn element in the obtained series of standard solutions is respectively tested by using an inductively coupled plasma atomic emission spectrometer. The model of the inductively coupled plasma atomic emission spectrometer used in the present invention is preferably Agilent 5110, which comes from Agilent Technologies Co., Ltd.

The test conditions when the present invention utilizes inductively coupled plasma atomic emission spectrometer to test Mn element emission light intensity are preferably as follows:

Wavelength: 257.610nm;

Plasma flow: 12L/min;

Auxiliary gas flow: 1.0L/min;

Atomizer flow rate: 0.7L/min;

RF power: 1200W;

Sample flow rate: 0.5L/min;

Measuring time: 5s;

Number of repetitions: 3 times;

Observation direction: radial.

In the present invention, after measuring the emitted light intensity of the Mn element in the series of standard solutions, the concentration of the Mn element in the series of quasi-solutions is taken as the abscissa, and the corresponding emitted light intensity is taken as the ordinate, corresponding one by one, and the standard curve is drawn . In the present invention, the linear correlation coefficient of the standard curve is required to be greater than 0.9995. When the present invention subsequently tests the Mn dissolution content of the sample solution to be tested, its content is within the range of the above-mentioned standard curve.

[About step d]:

Utilize the inductively coupled plasma atomic emission spectrometer to respectively test the emission intensity of the Mn element in the sample solution to be tested and the blank sample solution, and automatically calculate the concentration of the Mn element in the sample solution to be tested by the computer from the standard curve, which is manganese phosphate Dissolution of manganese in lithium iron cathode materials.

In the present invention, after the standard curve is obtained in the step c), the manganese dissolution content in the lithium iron manganese phosphate positive electrode material is measured through the step d). Specifically, the present invention first uses an inductively coupled plasma atomic emission spectrometer to test the emission intensity of the Mn element in the sample solution to be tested and the blank sample solution respectively.

Wherein, the sample solution to be tested is obtained by the following methods:

S1. Take 5.00g ± 0.05g of lithium manganese iron phosphate positive electrode material and 100mL of water in a beaker, stir and mix to obtain a mixed solution;

S2, then heat the mixed solution at 25°C for 2 hours to obtain a heat preservation solution;

S3. Suction-filtering the insulating solution with a microporous filter membrane with a pore size of 0.45 μm, and the obtained filtrate is the sample solution to be tested.

Regarding step S1:

The lithium manganese iron phosphate positive electrode material is preferably dried lithium manganese iron phosphate positive electrode material. The drying temperature is preferably 110° C., and the drying time is preferably 2 hours. In the present invention, when weighing the lithium manganese iron phosphate cathode material sample, 5.00g ± 0.05g sample is weighed, and the weighing accuracy is accurate to 0.01g. The water is preferably pure water. The measured amount of the water is 100mL. The beaker is preferably a 250mL beaker.

In the present invention, the step S1 preferably specifically includes:

Water-soluble: Measure 5.00g±0.05g of lithium manganese iron phosphate cathode material into a beaker, then measure 100mL of water and pour it into the beaker, then seal the mouth of the beaker with a parafilm, and shake the beaker gently to disperse the sample;

Stirring: the beaker is placed on a magnetic therapy stirrer, and stirred under the action of a magnetic stirring bar to obtain a mixed solution. Wherein, the rotational speed of the stirring is preferably 300r/min˜900r/min, more preferably 800r/min. The stirring time is preferably ≤60 min, more preferably 30 min. After stirring, a mixed solution was obtained.

Step S1 of the present invention is mainly to dissolve the lithium manganese iron phosphate positive electrode material in water, and transfer the manganese deintercalated from the lithium iron manganese phosphate positive electrode material to water, so as to facilitate subsequent measurement of the dissolved manganese content. In this step of the present invention, water is used for treatment instead of acid, otherwise the acid solution will destroy the structure of the lithium manganese iron phosphate, and the manganese dissolution content of the lithium manganese iron phosphate positive electrode material cannot be accurately measured.

Regarding step S2:

After the mixed solution is obtained in step S1, the mixed solution is kept warm, specifically, the beaker can be placed in a water bath for keeping warm. In the present invention, it is preferable to keep warm at 10°C to 30°C, more preferably at 25°C. The time for the heat preservation is preferably 0.5h to 4h, more preferably 2h. After the above heat preservation treatment, the heat preservation liquid of corresponding temperature is obtained. During the standing heat preservation process, the mixed solution is gradually layered, and the upper layer is clear liquid.

Regarding step S3:

After obtaining the insulating solution in step S2, filter it with a microporous filter membrane with a pore size of 0.45 μm, filter out the supernatant of the insulating solution, and transfer it to a clean beaker, which is the sample solution to be tested.

In the present invention, the deintercalated manganese in the test sample of the lithium iron manganese phosphate positive electrode material is dissolved through the above steps S1 to S3 to prepare the test sample solution.

In the present invention, the preparation of the blank solution in step d) is carried out according to the above steps S1-S3, the difference is that no lithium manganese iron phosphate cathode material is added in step S1, thereby forming a blank control solution.

In the present invention, after the sample solution to be tested and the blank sample solution are obtained, an inductively coupled plasma atomic emission spectrometer is used to respectively test the emitted light intensity of the Mn element in the sample solution to be tested and the blank sample solution. Wherein, the model of the inductively coupled plasma atomic emission spectrometer is the same as that described above, and will not be repeated here. The test condition when utilizing inductively coupled plasma atomic emission spectrometer to test Mn element emission light intensity is preferably as follows:

Wavelength: 257.610nm;

Plasma flow: 12L/min;

Auxiliary gas flow: 1.0L/min;

Atomizer flow rate: 0.7L/min;

RF power: 1200W;

Sample flow rate: 0.5L/min;

Measuring time: 5s;

Number of repetitions: 3 times;

Observation direction: radial.

The above-mentioned test conditions of the present invention are the best test conditions for manganese ions, which is beneficial to ensure the accuracy and precision of test results. In the present invention, after measuring the emitted light intensity of the Mn element in the sample solution to be tested and the blank sample solution, the computer will automatically calculate the concentration of the Mn element in the sample solution to be tested in combination with the standard curve, thereby obtaining the lithium iron phosphate cathode material The amount of manganese dissolved in. In the present invention, the unit of the measured Mn element content is ppm.

The detection method provided by the invention has the following beneficial effects:

1. The detection method of the present invention is simple, easy to operate and safe, can quickly detect the dissolved content of Mn, and improve the working efficiency of detecting the dissolved manganese.

2. The present invention uses an inductively coupled plasma atomic emission spectrometer to detect the dissolution of Mn. The plasma light source has good atomization, excitation and ionization capabilities, and the detection method has a good detection limit, which is generally 0.1ng/mL ~100ng/mL. Moreover, the present invention has a relatively low manganese dissolution content in the lithium iron manganese phosphate, which is at the ppm level.

3. The present invention uses an inductively coupled plasma atomic emission spectrometer to detect the dissolution of manganese, which is less affected by the sample matrix, so the reference sample does not need to be strictly matched with the matrix. Therefore this method has good accuracy.

Experimental results show that the relative standard deviation of the detection method of the present invention is only 0.41%, and the detection accuracy of Mn dissolution is relatively high.

In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only to further illustrate the features and advantages of the present invention, rather than limiting the claims of the present invention.

Example 1

a) Take 10.00mL of Mn element standard solution with a concentration of 1000μg/mL in a 100mL volumetric flask, add 2.00mL of concentrated hydrochloric acid (excellent grade), add water to make up to the mark, and shake well to obtain a Mn element concentration of 100.00μg /mL stock standard solution.

b) Take 0mL, 0.50mL, 1.00mL, and 2.00mL of the stock standard solution and place them in four 100mL volumetric flasks, add 2.00mL of concentrated hydrochloric acid (excellent grade), add water to the mark, and shake well. A series of standard solutions with concentrations of Mn element of 0 μg/mL, 0.50 μg/mL, 1.00 μg/mL and 2.00 μg/mL were obtained.

c) Utilize an inductively coupled plasma atomic emission spectrometer to respectively test the emitted light intensity of the Mn element in the series of quasi-solutions; then, take the concentration of the Mn element in the series of quasi-solutions as the abscissa, and the corresponding emitted light intensity as the ordinate , to draw a standard curve.

d) Utilize the inductively coupled plasma atomic emission spectrometer to test the emission intensity of the Mn element in the sample solution to be tested and the blank sample solution respectively, and automatically calculate the concentration of the Mn element in the sample solution to be tested by a computer from the standard curve, thereby obtaining Dissolution of manganese in lithium manganese iron phosphate cathode material;

Wherein, the sample solution to be tested and the blank sample solution are obtained by the following methods:

Take a sample of dried lithium manganese iron phosphate powder, weigh it 5 times in turn, each time about 5.00g, accurate to 0.01g, put it in five 250mL beakers, and make a good number (respectively recorded as Sample 1 to sample 5), do a blank test together with the sample; then use a 100mL graduated cylinder to accurately measure 100mL of pure water and pour them into the above 5 beakers and the blank sample beaker; immediately seal the mouth of the beaker with a parafilm and shake it gently Beakers to disperse the samples, then put all the beakers on a magnetic stirrer, add a magnetic stirrer, and stir at 800r/min for 30min to obtain a mixed solution (5 parts of sample solution and 1 part of blank solution). Then place the beaker in a water bath at 25°C for 2 h. Then, open the sealing film of the beaker, and use a microporous filter membrane with a pore size of 0.45 μm to filter the supernatant in the beaker on a suction filtration device, and transfer it to a clean 100mL beaker to obtain the sample solution to be tested (5 parts in total) and blank solution.

Among them, the model of the inductively coupled plasma atomic emission spectrometer used is Agilent 5110, and the test conditions for testing the emitted light intensity of the Mn element are as follows:

Wavelength: 257.610nm;

Plasma flow: 12L/min;

Auxiliary gas flow: 1.0L/min;

Atomizer flow rate: 0.7L/min;

RF power: 1200W;

Sample flow rate: 0.5L/min;

Measuring time: 5s;

Number of repetitions: 3 times;

Observation direction: radial.

All 5 sample solutions to be tested were tested in steps a) to d), and the test results of 5 samples were obtained in total, see Table 1.

Table 1: Test Results

It can be seen that the relative standard deviation of the sample is only 0.41%, and there is basically no significant difference in the results of the manganese dissolution content of multiple sampling tests of one sample. Therefore, the accuracy of the detection of Mn dissolution obtained by the present invention is relatively high.

In this paper, specific examples are used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only used to help understand the method of the present invention and its core idea, including the best mode, and also make any technology in the art Any person is capable of practicing the invention, including making and using any devices or systems, and performing any incorporated methods. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements close to the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal expressions of the claims.

Claims (10)

1. a detection method of manganese dissolution rate in lithium iron manganese phosphate cathode material, is characterized in that, comprises the following steps: a) Take 10.00mL of Mn element standard solution with a concentration of 1000μg/mL in a 100mL volumetric flask, add 2.00mL of concentrated hydrochloric acid, add water to make up to the mark, shake well, and obtain a reserve standard with a Mn element concentration of 100.00μg/mL solution; b) Take 0mL, 0.50mL, 1.00mL, and 2.00mL of the stock standard solution respectively and place them in four 100mL volumetric flasks, add 2.00mL of concentrated hydrochloric acid, add water to make up to the mark, shake well, and obtain the concentration of Mn element respectively A series of standard solutions of 0μg/mL, 0.50μg/mL, 1.00μg/mL, 2.00μg/mL; c) Utilize an inductively coupled plasma atomic emission spectrometer to respectively test the emitted light intensity of the Mn element in the series of quasi-solutions; then, take the concentration of the Mn element in the series of quasi-solutions as the abscissa, and the corresponding emitted light intensity as the ordinate , to draw a standard curve; d) Utilize the inductively coupled plasma atomic emission spectrometer to test the emission intensity of the Mn element in the sample solution to be tested and the blank sample solution respectively, and automatically calculate the concentration of the Mn element in the sample solution to be tested by the computer from the standard curve, which is Dissolution of manganese in lithium manganese iron phosphate cathode material; in, In the step d), the sample solution to be tested is obtained by the following method: S1. Take 5.00g ± 0.05g of lithium manganese iron phosphate positive electrode material and 100mL of water in a beaker, stir and mix to obtain a mixed solution; S2, then heat the mixed solution at 25°C for 2 hours to obtain a heat preservation solution; S3. Suction-filtering the heat preservation solution with a microporous filter membrane with a pore size of 0.45 μm, and the obtained filtrate is the sample solution to be tested; In the step d), the preparation of the blank sample solution is carried out according to the above steps S1-S3, the difference is that the lithium manganese iron phosphate cathode material is not added in the step S1. 2. detection method according to claim 1, is characterized in that, in described step c), utilizes inductively coupled plasma atomic emission spectrometer to test the test condition of Mn element emission light intensity to be: Wavelength: 257.610nm; Plasma flow: 12L/min; Auxiliary gas flow: 1.0L/min; Atomizer flow rate: 0.7L/min; RF power: 1200W; Sample flow rate: 0.5L/min; Measuring time: 5s; Number of repetitions: 3 times; Observation direction: radial. 3. detection method according to claim 1, is characterized in that, in described step d), utilizes inductively coupled plasma atomic emission spectrometer to test the test condition of Mn element emission light intensity as: Wavelength: 257.610nm; Plasma flow: 12L/min; Auxiliary gas flow: 1.0L/min; Atomizer flow rate: 0.7L/min; RF power: 1200W; Sample flow rate: 0.5L/min; Measuring time: 5s; Number of repetitions: 3 times; Observation direction: radial. 4. The detection method according to claim 1, characterized in that, in the step c), the linear correlation coefficient of the standard curve is greater than 0.9995. 5. detection method according to claim 1, is characterized in that, in described step a), the purity of described concentrated hydrochloric acid is superior order pure. 6. detection method according to claim 1, is characterized in that, in described step b), the purity of described concentrated hydrochloric acid is superior order pure. 7. The detection method according to claim 1, characterized in that, in the step S1, the accuracy of weighing the lithium manganese iron phosphate cathode material is 0.01 g. 8. The detection method according to claim 1, characterized in that, in the step S1, the lithium manganese iron phosphate positive electrode material is dried lithium manganese iron phosphate positive electrode material. 9. The detection method according to claim 8, characterized in that, the drying temperature is 110° C. and the drying time is 2 hours. 10. The detection method according to claim 1, characterized in that, in the step S2, the temperature of the heat preservation is 25°C, and the time is 2h; The model of the inductively coupled plasma atomic emission spectrometer is Agilent 5110.