CN110068567B - Method for testing cobalt content in manganese-containing material, method for testing electrode quality and method for testing battery quality - Google Patents
Method for testing cobalt content in manganese-containing material, method for testing electrode quality and method for testing battery quality Download PDFInfo
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Abstract
The invention provides a method for testing the cobalt content in a manganese-containing material, a method for testing the quality of an electrode and a method for testing the quality of a battery. The method for testing the cobalt content in the manganese-containing material comprises the following steps: dissolving the manganese-containing material to obtain a first mixture; adding a nitric acid-potassium chlorate saturated solution into the first mixture to obtain a second mixture; filtering the second mixture to obtain a filtrate to be detected and a precipitate to be detected; testing the first cobalt content in the filtrate to be tested by using a potentiometric titration method; testing the content of second cobalt in the sediment to be tested by using an inductively coupled plasma emission spectrometry; adding the first cobalt content and the second cobalt content to obtain a cobalt content in the manganese-containing material. The method is simple and convenient to operate, easy to realize, easy to industrialize, and high in accuracy and precision of testing the cobalt content.
Description
Technical Field
The invention relates to the technical field of material chemistry, in particular to a method for testing cobalt content in a manganese-containing material, a method for testing electrode quality and a method for testing battery quality.
Background
At present, in the ternary material for preparing the battery, the proportion of the cobalt element to the content of other elements (such as nickel, manganese and the like) in the ternary material has a great influence on the electrochemical performance of the ternary material after the ternary material is assembled into the battery, so the cobalt content in the ternary material must be accurately analyzed after the ternary material is prepared. However, since the ternary material used for preparing the battery usually contains manganese, and the accurate determination of the cobalt content in the manganese-containing material is one of the technical problems to be solved in the related art, that is, the cobalt content in the manganese-containing material cannot be accurately determined in the related art.
Thus, the existing related art for testing cobalt content in manganese-containing materials still remains to be improved.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, an object of the present invention is to provide a method for measuring cobalt content in a manganese-containing material, which is simple and convenient to operate, easy to implement, easy to industrialize, and has high accuracy or high precision in measuring cobalt content.
In one aspect of the invention, a method of testing the cobalt content of a manganese-containing material is provided. According to an embodiment of the invention, the method comprises: dissolving the manganese-containing material to obtain a first mixture; adding a nitric acid-potassium chlorate saturated solution into the first mixture to obtain a second mixture; filtering the second mixture to obtain a filtrate to be detected and a precipitate to be detected; testing the first cobalt content in the filtrate to be tested by using a potentiometric titration method; testing the content of second cobalt in the sediment to be tested by using an inductively coupled plasma emission spectrometry; adding the first cobalt content and the second cobalt content to obtain a cobalt content in the manganese-containing material. The inventor finds that the method is simple and convenient to operate, easy to implement and easy to industrialize, and the accuracy and the precision of the cobalt content testing are high.
According to an embodiment of the invention, prior to adding the saturated solution of potassium nitrate-chlorate to the first mixture, the method further comprises: adding metal ions to the first mixture.
According to an embodiment of the invention, the metal ions comprise Fe3+And Zn2+At least one of (1).
According to an embodiment of the invention, the metal ion is Zn2+。
According to an embodiment of the invention, the second cobalt content is not higher than 7.1% of the cobalt content.
According to an embodiment of the invention, prior to adding the saturated solution of potassium nitrate-chlorate to the first mixture, the method further comprises: subjecting the first mixture to an evaporation treatment.
According to an embodiment of the invention, the first mixture is subjected to an evaporation treatment to a volume of 1mL to 5 mL.
According to an embodiment of the invention, the first mixture is subjected to an evaporation treatment to a volume of 1mL to 2 mL.
According to an embodiment of the present invention, when the manganese content in the manganese-containing material is 12mg to 20mg, the volume of the saturated solution of potassium nitrate-chlorate added to the first mixture is 40mL to 50 mL.
According to an embodiment of the invention, before subjecting the second mixture to the filtration process, the method further comprises: subjecting the second mixture to a heat treatment.
According to the embodiment of the invention, the temperature of the heating treatment is 340-400 ℃.
According to an embodiment of the present invention, the temperature of the heat treatment is 340 to 380 ℃.
According to the embodiment of the invention, the time of the heating treatment is 8-12 min.
According to an embodiment of the invention, the method satisfies at least one of the following conditions: the recovery rate of the added standard is 99.7-101.1%; when the manganese content in the manganese-containing material is 12-20 mg, the relative standard deviation is not more than 0.64%.
According to an embodiment of the present invention, when the manganese content in the manganese-containing material is 12mg to 20mg, the method includes: dissolving the manganese-containing material with concentrated hydrochloric acid and hydrogen peroxide at the temperature of 150-250 ℃ to obtain a first mixture; adding a zinc sulfate solution containing zinc in a mass of 100mg to the first mixture; evaporating the first mixture until the volume is 1-2 mL; adding 40-50 mL of nitric acid-potassium chlorate saturated solution into the first mixture to obtain a second mixture; heating the second mixture for 8-12 min at 340-380 ℃; filtering the second mixture subjected to the heating treatment to obtain the filtrate to be detected and the precipitate to be detected; testing the first cobalt content in the filtrate to be tested by using a potentiometric titration method; testing the content of second cobalt in the sediment to be tested by using an inductively coupled plasma emission spectrometry; adding the first cobalt content and the second cobalt content to obtain a cobalt content in the manganese-containing material.
According to an embodiment of the invention, the manganese-containing material is a nickel-cobalt-manganese ternary material.
In another aspect of the invention, a method of testing the quality of an electrode is provided. According to an embodiment of the invention, the electrode comprises a manganese-containing material as described above, and the method comprises the step of testing the cobalt content of the manganese-containing material using the method as described above. The inventor finds that the method is simple and convenient to operate, easy to implement and easy to industrialize, and can well test the electrochemical performance of the electrode.
In yet another aspect of the invention, a method of testing the quality of a battery is provided. According to an embodiment of the invention, the battery comprises an electrode as described above, the method comprising the step of testing the quality of the electrode using the previous method. The inventor finds that the method is simple and convenient to operate, easy to implement, easy to industrialize and capable of well testing the electrochemical performance of the battery.
Drawings
Fig. 1 shows a schematic flow chart of a method for testing cobalt content in a manganese-containing material according to one embodiment of the present invention.
Fig. 2 shows a schematic flow chart of a method for testing cobalt content in a manganese-containing material according to another embodiment of the present invention.
Fig. 3 shows a schematic flow chart of a method for testing cobalt content in a manganese-containing material according to yet another embodiment of the present invention.
Fig. 4 shows a schematic flow chart of a method for testing cobalt content in a manganese-containing material according to yet another embodiment of the present invention.
Fig. 5 shows a schematic flow chart of a method for testing cobalt content in a manganese-containing material according to yet another embodiment of the present invention.
Detailed Description
The following describes embodiments of the present invention in detail. The following examples are illustrative only and are not to be construed as limiting the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.
In one aspect of the invention, a method of testing the cobalt content of a manganese-containing material is provided. According to an embodiment of the invention, referring to fig. 1, the method comprises the steps of:
s100: dissolving the manganese-containing material to obtain a first mixture.
According to an embodiment of the present invention, the first mixture obtained by dissolving the manganese-containing material with the preset mass contains manganese ions and cobalt ions, but it can be understood by those skilled in the art that the first mixture may also contain other metal ions, and therefore, redundant description is not repeated here.
According to the embodiment of the present invention, the specific process conditions for dissolving the manganese-containing material are not particularly limited, and those skilled in the art can flexibly select the manganese-containing material according to the actual needs as long as the requirements are met.
According to an embodiment of the present invention, the temperature at which the manganese-containing material is dissolved may be 150 to 250 ℃, specifically, 150 ℃, 180 ℃, 200 ℃, 220 ℃, or 250 ℃, or the like. Thus, the temperature at which the manganese-containing material is dissolved is appropriate, and the manganese-containing material is more easily dissolved.
According to the embodiment of the invention, the reagent for dissolving the manganese-containing material can be concentrated hydrochloric acid and hydrogen peroxide, so that the reagent is wide in source and easy to obtain, the manganese-containing material is easy to dissolve well, and the product obtained after dissolution is beneficial to subsequent application.
According to an embodiment of the present invention, as described above, if the reagent for dissolving the manganese-containing material includes concentrated hydrochloric acid, a chlorine gas having toxicity may be generated in a subsequent step, and thus after dissolving the manganese-containing material, sulfuric acid may be added to the first mixture and heated to volatilize hydrochloric acid remaining in the first mixture, and the sulfuric acid may be 1+9 sulfuric acid (concentrated sulfuric acid to water in a volume ratio of 1: 9). Therefore, chlorine gas is not generated in the subsequent steps, resulting in toxicity and environmental pollution.
In a specific embodiment of the present invention, the dissolving of the manganese-containing material to obtain the first mixture may specifically be weighing a certain amount of manganese-containing material, wetting with a small amount of water, adding concentrated hydrochloric acid, adding dropwise hydrogen peroxide, heating to dissolve, and then adding 1+9 sulfuric acid to the first mixture, and heating until the sulfuric acid smoke is exhausted. Therefore, the manganese-containing material can be well dissolved, and the subsequent application is facilitated.
S200: and adding a nitric acid-potassium chlorate saturated solution into the first mixture to obtain a second mixture.
According to an embodiment of the present invention, after adding the saturated solution of nitric acid and potassium chlorate to the first mixture, the nitric acid and potassium chlorate having strong oxidizing properties may chemically react with manganese ions in the first mixture to form manganese dioxide, which is present in the second mixture in the form of a precipitate.
According to the embodiment of the invention, after optimizing the volume of the saturated solution of potassium nitrate-chlorate added to the first mixture, the inventor finds that when the manganese content in the manganese-containing material is 12mg to 20mg, the manganese ions in the first mixture can be better generated into manganese dioxide by adding the saturated solution of potassium nitrate-chlorate to the first mixture in a volume of 40mL to 50mL, and specifically, the saturated solution of potassium nitrate-chlorate can be added in a volume of 40mL, 42mL, 44mL, 46mL, 48mL or 50 mL. At the moment, the volume of the added saturated solution of the nitric acid and the potassium chlorate is not too high or too low, so that the method for testing the cobalt content in the manganese-containing material has higher accuracy.
S300: and filtering the second mixture to obtain a filtrate to be detected and a precipitate to be detected.
According to the embodiment of the invention, the filtrate to be measured obtained after the second mixture is filtered contains cobalt ions, the precipitate to be measured contains manganese dioxide precipitate, and the manganese dioxide precipitate can adsorb part of the cobalt ions. That is, in the filtrate to be measured, a part of cobalt ions is contained; and the precipitate to be detected also contains part of cobalt ions, and the cobalt content in the manganese-containing material is the sum of the cobalt ion content in the filtrate to be detected and the cobalt ion content in the precipitate to be detected.
The specific manner of filtering the second mixture according to the embodiment of the present invention is not particularly limited, and those skilled in the art can flexibly select the second mixture according to the requirement as long as the requirement is satisfied. In some embodiments of the present invention, the second mixture may be filtered by using slow filter paper, so as to obtain the filtrate to be detected and the precipitate to be detected. Therefore, the method is simple and convenient to operate, easy to realize and easy for industrial production, and the filtrate to be detected and the precipitate to be detected can be effectively obtained.
S400: and testing the first cobalt content in the filtrate to be tested by using a potentiometric titration method.
According to the embodiment of the invention, when the potentiometric titration method is used for testing the first cobalt content in the filtrate to be tested, Co is used2+Is easily oxidized by oxygen in the air to form Co under the alkaline environment3+Thus, the Co in the filtrate to be tested was tested by directly using the potentiometric titration method2+The method for testing the content of the first cobalt in the filtrate to be tested cannot obtain an accurate test result, so that when the content of the first cobalt in the filtrate to be tested is tested by using a potentiometric titration method, excessive oxidant can be added into the filtrate to be tested to enable Co to be added2+Oxidation to Co3+Then use Co2+The standard solution is back titrated for excess oxidant. Therefore, the potentiometric titration method is used for testing the content of the first cobalt in the filtrate to be tested, and the test result is more accurate.
According to an embodiment of the present invention, the oxidizing agent may be potassium ferricyanide. When the content of the first cobalt in the filtrate to be tested is tested by using a potentiometric titration method, excessive potassium ferricyanide solution is added into the filtrate to be tested to oxidize Co in the filtrate to be tested2+Then use Co2+Back titration of excess Fe with standard solution3+And further, the test result of testing the first cobalt content in the filtrate to be tested by using a potentiometric titration method is more accurate.
According to the embodiment of the present invention, as described above, the calculation formula of the first cobalt content in the filtrate to be measured is as follows:
wherein, W(Co)Is the first cobalt content (%);
is the concentration (mol/L) of the potassium ferricyanide solution;
is the volume (mL) of potassium ferricyanide solution added to the filtrate to be tested; c(Co)Is Co2+Concentration of standard solution (mol/L); v(Co)For back titration of excess Fe3+Co consumed in the course of2+Volume of standard solution (mL); m is the preset mass of the manganese-containing material in the step S100; 58.93 is the relative atomic mass of cobalt. Therefore, the first cobalt content in the filtrate to be detected can be obtained more accurately.
According to the embodiment of the present invention, further, when the content of the first cobalt in the filtrate to be tested is tested by using a potentiometric titration method, an acidity regulator may be added to the filtrate to be tested to regulate the filtrate to be tested to be neutral, then a masking agent is added to mask interference of other ions in the solution to be tested, and a reducing agent is added to make cobalt in the solution to be tested to be Co-based2+Is present in order to make the test result of the first cobalt content more accurate.
In a specific embodiment of the present invention, when the potentiometric titration method is used to test the first cobalt content in the filtrate to be tested, the specific operations may be: adding 2 drops of methyl red indicator into the filtrate to be detected, then dropwise adding ammonia water until the red color of the indicator fades, so as to adjust the pH of the filtrate to be detected to be 6.5-7.5, then adding ammonium chloride, ammonium citrate-ammonia water mixed solution into the filtrate to be detected, which is adjusted to be 6.5-7.5, and standing. Finally to the saidAdding excessive potassium ferricyanide solution into the filtrate to be detected to oxidize Co in the filtrate to be detected2+Then using Co on an automatic potentiometric titrator2+Back titration of excess Fe with standard solution3+. Therefore, the method is simple and convenient to operate, easy to realize and easy to industrialize.
S500: and testing the content of the second cobalt in the precipitate to be tested by using an inductively coupled plasma emission spectrometry.
According to the embodiment of the present invention, the specific operation of testing the second cobalt content in the precipitate to be tested by using inductively coupled plasma emission spectrometry may be: and dissolving the precipitate to be detected by using a mixed solution of concentrated hydrochloric acid and hydrogen peroxide, heating and boiling, completely removing the hydrogen peroxide, and fixing the volume. And then testing the second cobalt content by using an inductively coupled plasma spectrometer, wherein the detection wavelength of the cobalt element is (228 +/-1) nm or (238 +/-1) nm. Therefore, the method is simple and convenient to operate, easy to realize, quick and accurate, and easy to industrialize.
S600: adding the first cobalt content and the second cobalt content to obtain a cobalt content in the manganese-containing material.
According to the embodiment of the present invention, as described above, the filtrate to be measured obtained after the second mixture is filtered contains cobalt ions, and the precipitate to be measured obtained also contains a part of cobalt ions, and the cobalt content in the manganese-containing material should be the sum of the cobalt ion content in the filtrate to be measured and the cobalt ion content in the precipitate to be measured, that is, the cobalt content in the manganese-containing material is obtained by adding the first cobalt content and the second cobalt content.
As a result of intensive research and extensive research on a method for measuring the content of cobalt in a manganese-containing material, the inventors have found that, in the related art, when the content of cobalt in a manganese-containing material is measured by potentiometric titration, the measurement result is always higher than the actual result because, when the content of cobalt in a manganese-containing material is measured, if manganese in the manganese-containing material is not removed, the final measurement result is the content of cobalt and manganese in the manganese-containing material, and therefore, when the content of cobalt in a manganese-containing material is measured, it is necessary to remove manganese in the manganese-containing material to remove the interference of the manganese element with the measurement of the content of cobalt.
According to the embodiment of the invention, further, when testing the cobalt content in the manganese-containing material, the inventor determines to remove the manganese element in the form of precipitation by using a nitric acid-potassium chlorate saturated solution, thereby removing the interference of the manganese element on the cobalt content measurement. However, after a lot of experiments, the inventors found that when the cobalt content in the manganese-containing material is tested after the manganese element is removed in the form of precipitate, the measurement result is rather low. In this regard, the inventors have conducted extensive and intensive studies and experimental verification, and found that the reason why the test result of testing the cobalt content in the manganese-containing material after removing the manganese element is low is that when the manganese element is removed in the form of precipitate, the precipitate also adsorbs a certain amount of cobalt, thereby resulting in a low test result.
Based on the above studies, the inventors have further improved the method for testing the cobalt content in manganese-containing materials, namely: when manganese in a manganese-containing material is removed in the form of a precipitate by using a saturated solution of nitric acid and potassium chlorate, cobalt contents, namely the first cobalt content and the second cobalt content, in the obtained filtrate and the obtained precipitate are respectively tested, and then the first cobalt content and the second cobalt content are added to obtain the cobalt content in the manganese-containing material. Therefore, the test result of the method for testing the cobalt content in the manganese-containing material can be effectively compensated, so that the accuracy and the precision of testing the cobalt content are high.
In other embodiments of the present invention, referring to fig. 2, prior to adding the saturated solution of potassium nitrate-chlorate to the first mixture, the method may further comprise the steps of:
s700: adding metal ions to the first mixture.
According to the embodiments of the present invention, based on the above studies, the inventors found that, even when the cobalt content in the manganese-containing material is tested, the first cobalt content and the second cobalt content obtained by the test are respectively added, and although the accuracy of the obtained test result is high compared with that in the related art, the test result is still not ideal. Based on this, the inventors have conducted extensive and intensive studies and experimental verification thereon, and surprisingly found that when metal ions are added to the first mixture before the nitric acid-potassium chlorate saturated solution is added to the first mixture, the accuracy of the test method can be further significantly improved.
According to an embodiment of the invention, the species of the metal ion may be Mg2+、Ca2+、Zn2+And Fe3+And the like. Further, the inventors found that when the metal ion is Zn2+Or Fe3+Compared with the method without adding metal ions, the method for testing the cobalt content in the manganese-containing material has the advantage that the accuracy of the test result is obviously improved.
After a great deal of experimental verification, the inventors of the present invention have considered that, when a manganese dioxide precipitate is formed by adding a saturated solution of potassium nitrate-chlorate after adding metal ions to the first mixture, the first mixture contains both cobalt ions and the previously added metal ions, so that the formed manganese dioxide precipitate produces competitive adsorption of cobalt ions and the previously mentioned metal ions, and the activity of the manganese dioxide surface is occupied by the metal ions, so that the amount of cobalt ions adsorbed by the manganese dioxide precipitate is reduced, i.e., the content of cobalt ions in the subsequent precipitate to be measured is reduced, and a larger amount of cobalt ions remains in the filtrate to be measured. However, as mentioned above, in theory, whatever the first cobalt content and the second cobalt content are too low, the cobalt content in the manganese-containing material is always obtained by adding the first cobalt content and the second cobalt content. However, experimental observations have shown that after addition of metal ions to the first mixture, such that the second cobalt content is reduced, and correspondingly the first cobalt content is increased, results from testing the cobalt content in the manganese-containing material are more accurate. In this regard, after further analysis, the inventors have found that, in the method described above, although the deviation of the test result caused by the cobalt adsorbed in the precipitate to be tested is compensated, the accuracy of the method can be further improved only when the cobalt adsorbed in the precipitate to be tested (i.e., the second cobalt content) is suitable for testing by inductively coupled plasma emission spectroscopy. That is, after adding the saturated solution of nitric acid and potassium chlorate to the first mixture and filtering the obtained second mixture, the amount of cobalt directly adsorbed in the precipitate to be tested is not a known amount, and the amount of cobalt adsorbed in the precipitate to be tested (i.e., the second cobalt content) is not necessarily suitable for the known analytical test method to perform the analytical test, so that the second cobalt content needs to be adjusted to be suitable for the analytical test using the known analytical test method by adding metal ions to the first mixture to generate competitive adsorption as described above. Of course, in the present invention, the analytical test method for testing the second cobalt content is inductively coupled plasma emission spectroscopy. That is, the inventors have made the accuracy of the second cobalt content in the present method higher by adding metal ions to the first mixture, and thus made the method more accurate.
According to the embodiments of the present invention, based on the above analysis, the inventors conducted experiments on competitive adsorption of the metal ions added to the first mixture with cobalt ions, and from the experimental results, when the metal ions are Zn2+Or Fe3+In this case, the amount of cobalt adsorbed in the precipitate to be measured (i.e., the second cobalt content) is significantly lower than that when other kinds of metal ions are added. Thus, the inventors believe that the accuracy of the method of testing the cobalt content of a manganese-containing material is improved by minimizing the second cobalt content as described above.
Further, according to the embodiment of the present invention, after a lot of experimental verification, the inventors found that when the second cobalt content is not higher than 7.1% of the cobalt content in the manganese-containing material, the accuracy of the test result of the cobalt content in the manganese-containing material described above is further improved, and the precision is further improved.
According to an embodiment of the present invention, as mentioned above, when the metal ion is Zn2+Or Fe3+The method for testing the cobalt content in the manganese-containing materialThe accuracy of the test results is significantly improved compared to when no metal ions are added, and further, when testing the cobalt content, due to Fe3+The coexistence of (A) and (B) requires masking with an excess of ammonium citrate as a masking agent, which, if not completely, would affect the test results, and thus the metal ion added to the first mixture is Zn2+The method for testing the cobalt content in the manganese-containing material achieves better accuracy.
In still other embodiments of the present invention, further, with reference to fig. 3, prior to adding the saturated solution of potassium nitrate-chlorate to the first mixture, the method may further comprise the steps of:
s800: subjecting the first mixture to an evaporation treatment.
The inventors have further optimized the method for testing the cobalt content of a manganese-containing material according to an embodiment of the present invention and have found that the accuracy of the method for testing the cobalt content of a manganese-containing material can be further improved by subjecting the first mixture to an evaporation treatment before adding the saturated solution of potassium nitrate-chlorate to the first mixture.
According to the embodiment of the present invention, the inventors have conducted intensive studies on the volume of the first mixture after the evaporation treatment, and have found that the accuracy of this method is high when the first mixture is subjected to the evaporation treatment to a volume of 1mL to 5mL, and specifically, the first mixture may be subjected to the evaporation treatment to a volume of 1mL, 2mL, 3mL, 4mL, 5mL, or the like. Further, when the first mixture is subjected to evaporation treatment to a volume of 1mL to 2mL, the accuracy of the method is further improved.
In still other embodiments of the present invention, further, referring to fig. 4, before the second mixture is subjected to the filtering process, the method may further include the steps of:
s900: subjecting the second mixture to a heat treatment.
According to the embodiment of the invention, the inventor finds that the second mixture is subjected to heating treatment before being subjected to filtering treatment, so that the precipitate to be tested is completely precipitated, the reaction rate can be increased, and the testing efficiency can be improved.
According to the embodiment of the present invention, further, the inventor optimizes the temperature and time of the heating treatment, when the temperature of the heating treatment is 340 ℃ to 400 ℃, specifically, 340 ℃, 360 ℃, or 380 ℃ and the like; the time of the heating treatment is 8min to 12min, and specifically, when the time of the heating treatment can be 8min, 10min or 12min, the method has high accuracy.
According to an embodiment of the invention, the method satisfies at least one of the following conditions: the recovery rate of the added standard is 99.7-101.1%; when the manganese content in the manganese-containing material is 12-20 mg, the relative standard deviation is not more than 0.64%. Specifically, the recovery of the spiked by the method may be 99.7%, 99.9%, 101.1%, or the like. Therefore, the method for testing the cobalt content in the manganese-containing material is high in accuracy and precision.
In addition, in a specific embodiment of the present invention, referring to fig. 5, when the manganese content in the manganese-containing material is 12mg to 20mg, the method includes: s100': dissolving the manganese-containing material with concentrated hydrochloric acid and hydrogen peroxide at the temperature of 150-250 ℃ to obtain a first mixture; s700': adding a zinc sulfate solution containing zinc in a mass of 100mg to the first mixture; s800': evaporating the first mixture until the volume is 1-2 mL; s200': adding 40-50 mL of nitric acid-potassium chlorate saturated solution into the first mixture to obtain a second mixture; s900': heating the second mixture for 8-12 min at 340-380 ℃; s300': filtering the second mixture subjected to the heating treatment to obtain the filtrate to be detected and the precipitate to be detected; s400: testing the first cobalt content in the filtrate to be tested by using a potentiometric titration method; s500: testing the content of second cobalt in the sediment to be tested by using an inductively coupled plasma emission spectrometry; s600: adding the first cobalt content and the second cobalt content to obtain a cobalt content in the manganese-containing material. Therefore, in the method for testing the cobalt content in the manganese-containing material, all parameters are better, so that the accuracy of the method is obviously improved compared with the method for testing the cobalt content in the related technology, the precision is obviously improved, and the method is simple and convenient to operate, easy to implement, lower in cost and easy to industrialize.
In some embodiments of the invention, the manganese-containing material may be a nickel-cobalt-manganese ternary material. Therefore, the method is suitable for testing the cobalt content of the nickel-cobalt-manganese ternary material, and further the cobalt content in the positive active material is obtained through testing in the production process of the battery, particularly the production process of the lithium ion battery, so that the electrochemical performance of the positive material in the lithium ion battery is optimized.
In another aspect of the invention, a method of testing the quality of an electrode is provided. According to an embodiment of the invention, the electrode comprises a manganese-containing material as described above, and the method comprises the step of testing the cobalt content of the manganese-containing material using the method as described above. The inventor finds that the method is simple and convenient to operate, easy to implement and easy to industrialize, and can well test the electrochemical performance of the electrode.
According to the embodiment of the present invention, it can be understood by those skilled in the art that the method for testing the quality of the electrode includes other testing steps besides the steps for testing the cobalt content in the manganese-containing material described above, and thus the description thereof is not repeated.
In yet another aspect of the invention, a method of testing the quality of a battery is provided. According to an embodiment of the invention, the battery comprises an electrode as described above, the method comprising the step of testing the quality of the electrode using the previous method. The inventor finds that the method is simple and convenient to operate, easy to implement, easy to industrialize and capable of well testing the electrochemical performance of the battery.
According to the embodiments of the present invention, it can be understood by those skilled in the art that the method for testing the quality of the battery includes other testing steps besides the steps for testing the quality of the electrode described above, and thus the description thereof is omitted.
The following describes embodiments of the present invention in detail. The instruments and reagents used in the examples are as follows:
potentiometric titrators model 916 (switzerland); iCAP7400 inductively coupled plasma spectrometer (Thermo Scientific, usa); smart Plus-N ultra pure water machine (shanghai li kang); an electronic balance: sensitivity 0.0001 g; ICP-OES cobalt standard solution: 1000ug/mL, using 5% HCl as the matrix, diluting to prepare 0, 2.5ug/mL, 5ug/mL, 10ug/mL standard curve series; analytically pure hydrochloric acid: HCl content of about 36% to 38%; analytically pure nitric acid: HNO3The content is about 70%; hydrogen peroxide: the mass concentration is 30 percent; (1+9) sulfuric acid: 1 volume sulfuric acid and 9 volumes water; zinc sulfate solution: weighing 8.8g of zinc sulfate heptahydrate, adding water to dissolve the zinc sulfate heptahydrate, and fixing the volume to 200mL, wherein each milliliter of the solution contains 10mg of zinc; nitric acid-potassium chlorate saturated solution: weighing 500mL of concentrated nitric acid into a brown reagent bottle, adding potassium chlorate, stirring until the potassium chlorate is not dissolved any more, and standing for 24 hours for use; methyl red indicator: weighing 0.2g of methyl red, dissolving in absolute ethyl alcohol, metering the volume to 100mL, and shaking up; ammonia water: the mass concentration is more than or equal to 28 percent; ammonium chloride: analyzing and purifying; ammonium citrate-ammonia mixed solution: weighing 50g of ammonium citrate, placing the ammonium citrate in a 1000mL beaker, adding 500mL of water and 500mL of ammonia water, and uniformly mixing; cobalt standard solution: accurately weighing 1g of metal cobalt (Co is more than or equal to 99.98 percent), placing the metal cobalt into a 250mL beaker, adding 50mL of dilute nitric acid (the volume ratio of the nitric acid to the water is 1: 4), placing the metal cobalt on an electric heating plate with the temperature set to be 100 ℃, heating and dissolving the metal cobalt, cooling the metal cobalt to the room temperature, transferring the metal cobalt into a 1000mL volumetric flask to fix the volume and shake the metal cobalt uniformly; standard potassium ferricyanide solution: weighing 11.2g of potassium ferricyanide, placing the potassium ferricyanide in a 250mL beaker, adding about 150mL of water, placing the beaker on an electric hot plate set at the temperature of 70-80 ℃, heating and dissolving, filtering the solution into a 1000mL volumetric flask, adding water to a constant volume to a scale mark, shaking up the solution, storing the solution in a brown reagent bottle, and calibrating the solution before use.
Example 1
Weighing 0.1g of nickel-cobalt-manganese ternary material into a 250mL beaker, wetting a sample with a small amount of water, washing the wall of the beaker, adding 5mL of hydrochloric acid, dropwise adding a few drops of hydrogen peroxide, heating for dissolving, adding 10mL of zinc sulfate solution (zinc content is 100mg), adding 1mL (1+9) of sulfuric acid, heating on a low-temperature electric furnace until the sulfuric acid smoke is exhausted, slightly cooling, adding a small amount of deionized water, washing the wall of the beaker, heating for dissolving the sample, evaporating to about 1-2 mL, adding 50mL of nitric acid-potassium chlorate saturated solution, placing on an electric heating plate at 340-380 ℃ for heating treatment, covering a surface dish after yellow green smoke is exhausted, boiling for 4-6 minutes, supplementing 0.5g of potassium chlorate solid, continuing to boil for 4-6 minutes, taking down for cooling, washing a surface dish and the beaker with water until the liquid volume reaches about 80mL, filtering into another 250mL beaker by using slow-speed filter paper, washing the beaker with hot water and precipitating for a plurality of times, and further obtaining the filtrate to be detected and the precipitate to be detected.
Adding 2 drops of methyl red indicator into the filtrate to be detected, dropwise adding ammonia water until the red color of the indicator is removed, wherein the pH of the solution is approximately equal to 7, adding 5g of ammonium chloride, 50mL of ammonium citrate-ammonia water mixed solution, adding iron potassium hydride solution and about 5mL of excessive solution, and performing an instrument-set program on an automatic potentiometric titrator by using Co2+And titrating the standard solution, automatically identifying the end point by an instrument, and calculating the result to obtain the first cobalt content.
And washing the precipitate to be tested obtained by filtering with a hydrochloric acid-hydrogen peroxide mixed solution to an original beaker, heating and boiling, completely removing the hydrogen peroxide, metering the volume to a 100mL volumetric flask, and testing the content of the second cobalt in the precipitate to be tested by using an inductively coupled plasma emission spectrometry.
Adding the first cobalt content and the second cobalt content to obtain a cobalt content in the manganese-containing material.
And (3) testing results:
(1) the manganese content in the nickel-cobalt-manganese ternary material in example 1 is 12% (0.1 g of sample is weighed, namely 12mg of manganese is contained), the test is carried out according to the test method in example 1, and 6 groups are tested in parallel, and the test results are shown in table 1;
TABLE 1 test results and precision test results
As can be seen from the data in Table 1, the results of the parallel test of the same nickel-cobalt-manganese ternary material for 6 times are relatively small in deviation, and the method is high in precision and stable in results.
(2) The same nickel-cobalt-manganese ternary material was tested according to the test method in example 1 and the 1-nitroso-2-naphthol gravimetric analysis method in the related art, and a standard recovery experiment was performed, with the test results shown in table 2;
TABLE 2 accuracy test results of the determination method
| Analytical method | Cobalt content (%) | Cobalt content (%) (10% after addition of the standard) | Recovery (%) |
| Example 1 | 10.09 | 20.20 | 101.1 |
| 1-nitroso-2-naphthol gravimetric analysis method | 10.18 | 20.35 | 101.7 |
As can be seen from the data in Table 2, when the results of the cobalt measurement by the method used in example 1 and the cobalt measurement by the 1-nitroso-2-naphthol gravimetric analysis method are compared, the results of the two methods are similar, and the normalized recovery rate is close to 100%, which indicates that the method has higher accuracy, but the operation steps and the test period are obviously better than those of the 1-nitroso-2-naphthol gravimetric analysis method.
(3) Preparing a standard sample of a nickel-cobalt-manganese ternary material, wherein the sample contains 50mg of nickel and 10mg of cobalt, and respectively adding Mn with different contents2+(manganese acetate tetrahydrate), verification of the procedure in example 1 for Mn2+The interference cancellation effect of (a), the results are shown in table 3;
TABLE 3 experiment of the interference elimination effect of coexisting manganese
| Mn2+Addition amount/mg | 5 | 10 | 15 | 20 |
| Cobalt content determination/mg | 10.04 | 9.97 | 9.98 | 10.03 |
From the data in Table 3, it can be seen that 20mg of Mn was added2+The cobalt determination of the method in example 1 is not affected, and shows that the As in the nickel-cobalt-manganese ternary material can be obtained by treating the sample with the nitric acid-potassium chlorate saturated solution3+、Fe2+、Cr3+Oxidized to a high valence, Mn2+Oxidation to MnO2The As in the nickel-cobalt-manganese ternary material is actually removed in a precipitation form3+、Fe2+、Cr3+Is low and does not influence the test result of the cobalt content per se, while Mn2+In an amount ofGenerally below 20%, therefore, the method of the invention can completely eliminate the interference when the manganese content is below 20%.
(4) Control experiments were performed on the test method of example 1, one set of experiments was performed as in example 1; another set of experiments was conducted without addition of Zinc sulfate solution (Zn)2+) Except that, the same method as in example 1 was used, the test results are shown in table 4;
TABLE 4 whether or not Zn is added2+Influence of the measured value of the second cobalt content
| Test conditions | Second cobalt content measurement (%) |
| Without addition of Zn2+ | 0.98 |
| Adding Zn2+ | 0.67 |
As can be seen from the data in Table 4, under heating conditions due to hydration of MnO2To Co2+Has strong adsorption capacity, and is added with competitive ion Zn with high concentration2+To hydrate MnO2Is heavily occupied by active sites, making it Co-tolerant2+Is limited in adsorption capacity and Co reduction2+So as to ensure that the second cobalt content of an inductively coupled plasma emission spectrometry (ICP-OES) test is in a reasonable range and the excessive Zn2+The potentiometric titration and the ICP-OES test in the subsequent steps are not interfered, and the accuracy of the result is not influenced.
EXAMPLE 2 selection of Metal ions
Preparation of nickel cobaltA standard sample of manganese ternary material containing 50mg of nickel, 10mg of cobalt and 20mg of manganese was prepared according to the test method of example 1 without adding the zinc sulphate solution, replacing it with 100mg of Na+、Mg2+、Ca2 +、Fe3+The solution of (1) is mixed with a standard sample of nickel-cobalt-manganese ternary material without metal ions, and 100mg of Zn is added2+The standard sample of the nickel-cobalt-manganese ternary material was subjected to a simultaneous experiment, and the results of testing the content of cobalt adsorbed in the precipitate to be tested are shown in table 5:
TABLE 5 cobalt content adsorbed in the precipitate to be tested after adding the same amount of metal ions
| Sample (I) | Without addition of metal ions | Na+ | Mg2+ | Ca2+ | Zn2+ | Fe3+ |
| Adsorbed cobalt content in the precipitate (mg) | 0.98 | 1.01 | 0.96 | 0.88 | 0.67 | 0.50 |
The results show that the addition of Na compared to the absence of metal ions+、Mg2+、Ca2+Then, the influence on the content of the adsorbed cobalt in the precipitate is small, and Zn is added2+、Fe3+And then the adsorption amount is reduced to a certain degree.
Example 3 Effect of the volume of the first mixture before adding saturated solution of nitric acid and potassium chlorate on the results of the test
According to the testing method in the embodiment 1, after the sulfuric acid smoke is removed, deionized water with different amounts is added to extract a sample, 50mL of nitric acid-potassium chlorate saturated solution is added to carry out oxidation separation, and the same nickel-cobalt-manganese ternary material is tested, wherein the manganese content in the sample is 12%, and the cobalt content in the sample is 10% (0.1 g of the sample is weighed, namely the sample contains 12mg of manganese). The test results were as follows:
TABLE 6 Effect of the volume of the first mixture before adding the saturated solution of nitric acid and potassium chlorate on the test results
As can be seen from the data in Table 6, the test results increased with increasing volume of the solution, presumably Mn in the first mixture2+Incomplete separation results in a large interference of the measurement result by manganese. When the volume of the solution is 1-2 mL, the test result is close to the true value.
Example 4 Effect of the amount of saturated nitric acid-potassium chlorate solution added on the results of measurement
Preparing a standard sample of the nickel-cobalt-manganese ternary material, wherein the sample contains 50mg of nickel, 10mg of cobalt and 20mg of manganese, adding different amounts of nitric acid-potassium chlorate saturated solutions according to the test method in the example 1, and testing the cobalt content of the standard sample of the nickel-cobalt-manganese ternary material according to the test results in table 7:
TABLE 7 influence of the amount of the nitric acid-potassium chlorate saturated solution added on the measurement results
| Adding amount/mL of saturated solution of nitric acid-potassium chlorate | 10 | 20 | 30 | 40 | 50 |
| Cobalt content/mg | 17.58 | 12.66 | 11.64 | 10.11 | 9.97 |
| Recovery rate | 175.8％ | 126.6％ | 116.4％ | 101.1％ | 99.7％ |
As can be seen from the data in Table 7, when the amount of the saturated solution of nitric acid and potassium chlorate was 40 mL-50 mL, the measured results tended to be stable and to be close to the theoretical values.
Example 5 influence of temperature and time of Heat treatment on measurement results
According to the test method in the embodiment 1, different heating temperatures and different heating times are selected to test the same nickel-cobalt-manganese ternary material, wherein the manganese content of the nickel-cobalt-manganese ternary material is 12%, and the cobalt content of the nickel-cobalt-manganese ternary material is 10% (0.1 g of sample is weighed, namely the manganese content is about 12 mg). The test results are shown in table 8:
TABLE 8 influence of temperature and time of heat treatment on measurement results
From the data in table 8: when the temperature of the heating treatment is 340-400 ℃ and the time is 8-12 min, the test result of the cobalt content is stabilized at about 10%, but when the temperature is 380-400 ℃, the amount of the adsorbed cobalt in the sediment to be tested is more, which is not beneficial to the ICP-OES method to determine the second cobalt content, so the temperature of the heating treatment is selected to be 340-380 ℃ and the time is selected to be 8-12 min; in addition, in the test process of example 1, potassium chlorate solids were replenished once to replenish the reaction consumption of potassium chlorate, making the reaction proceed more thoroughly.
In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (3)
1. The method for testing the cobalt content in a manganese-containing material is characterized in that the manganese-containing material is a nickel-cobalt-manganese ternary material, the manganese content in the manganese-containing material is 12-20 mg, the relative standard deviation is not more than 0.64%, and the standard recovery rate is 99.7-101.1%, and the method comprises the following steps:
dissolving the manganese-containing material with concentrated hydrochloric acid and hydrogen peroxide at the temperature of 150-250 ℃ to obtain a first mixture;
adding a zinc sulfate solution containing zinc in a mass of 100mg to the first mixture;
evaporating the first mixture until the volume is 1-2 mL;
adding 40-50 mL of nitric acid-potassium chlorate saturated solution into the first mixture to obtain a second mixture;
heating the second mixture at 340-380 ℃ for 8-12 min;
filtering the second mixture subjected to the heating treatment to obtain a filtrate to be detected and a precipitate to be detected;
testing the first cobalt content in the filtrate to be tested by using a potentiometric titration method;
testing the second cobalt content in the precipitate to be tested by using an inductively coupled plasma emission spectrometry, wherein the second cobalt content is not higher than 7.1% of the cobalt content;
adding the first cobalt content and the second cobalt content to obtain a cobalt content in the manganese-containing material.
2. A method of testing the cobalt content of an electrode comprising the manganese-containing material of claim 1, comprising the step of testing the cobalt content of the manganese-containing material using the method of claim 1.
3. A method of testing the cobalt content of a battery comprising an electrode as claimed in claim 2, wherein the method comprises the step of testing the cobalt content of the electrode using the method of claim 2.
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