A method for detecting a cathode material of a lithium-ion battery

Abstract

The present invention discloses a method for detecting a cathode material of a lithium-ion battery, which relates to the technical field of cathode material detection, and includes steps such as marking and mixing the cathode material and a reaction solvent, reacting the sample, drying and cleaning the sample, and measuring the discharge specific capacity. In view of the situation that during the use of lithium-ion batteries, irreversible chemical reactions will occur between the cathode material and the moisture and other components in the electrolyte, and it is necessary to pre-screen cathode materials with high compatibility with the solvent. With the aid of a synchronous reaction device, the detection method of the present invention has the advantages of simple operation, obvious effect, high contrast, and short experimental time, and is of great significance for evaluating and screening cathode materials.

Description

Technical Field

[0001] The present invention relates to the technical field of cathode material detection, and particularly to a method for detecting a cathode material of a lithium-ion battery. Background Art

[0002] In recent years, rechargeable lithium-ion batteries have become an important part of the global battery market. Lithium-ion batteries mainly consist of four main materials: cathode material, anode material, separator, and electrolyte. Among these main materials, the cathode material mainly determines the capacity, energy density, and power density of the lithium-ion battery. Currently, the mainstream cathode materials in use, such as lithium cobaltate and lithium iron phosphate, have problems such as high-temperature stability in common electrolytes and often undergo chemical reactions with the electrolyte.

[0003] During the charge and discharge process of a lithium-ion battery, the materials on the positive and negative electrode plates will undergo irreversible chemical reactions with the moisture and other components in the electrolyte. Among them, transition metal ions usually dissolve out from the cathode material in the electrolyte, and a hard film will also form on the surface of the material, delaying the kinetic reaction of the electrode. In addition, the moisture in the electrolyte will also participate in the reaction during the use of the battery, generating a high concentration of acid (such as hydrofluoric acid), which is very harmful to materials such as lithium cobaltate and lithium iron phosphate. Therefore, it is particularly important to screen out cathode materials that dissolve less transition metal ions and are less affected by moisture in a known electrolyte, which can more quickly evaluate the cathode materials compatible with the electrolyte and ultimately improve the performance of the battery cell such as capacity, internal resistance, and cycle. In the actual production or product development stage, a method for quickly and effectively evaluating and screening the cathode materials of lithium-ion batteries is of great significance for effectively improving the performance of the battery cell and reducing costs. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for detecting a cathode material of a lithium-ion battery, which can standardize the evaluation of the compatibility of several or even dozens of cathode materials to be evaluated with the electrolyte in a relatively short time, so as to screen out the cathode material with the best compatibility with the electrolyte.

[0005] To solve the above problems, the present invention provides the following technical solutions:

[0006] A method for detecting a cathode material of a lithium-ion battery includes the following specific steps:

[0007] S1. Number the lithium iron phosphate cathode material to be detected, and then use deionized water, a mixed solution of electrolyte and water with a certain ratio, and pure electrolyte as reaction solvents;

[0008] S2. Divide each type of lithium iron phosphate cathode material into several portions on average, and load them into the synchronous reaction device respectively. After sealing the synchronous reaction device, rotate the annular groove. During the rotation of the annular groove, various reaction solvents are periodically and repeatedly added to the lithium iron phosphate cathode material. The added weight of the reaction solvent is 2-3 times that of the lithium iron phosphate cathode material, ensuring that several different solid-liquid mixed reaction samples are prepared after mixing each type of lithium iron phosphate with each type of solvent;

[0009] S3. After the preparation of the solid-liquid mixed reaction samples is completed, let them stand in situ in the annular groove for 2 h, and then keep the temperature constant at 60 °C and react for 24 h;

[0010] S4. After the reaction is completed, rotate the annular groove to filter out the reaction solvent in the solid-liquid mixed reaction samples. The remaining solids are dried and then taken out from the annular groove 4 respectively for subsequent treatment;

[0011] S5. After the dried solids are placed at room temperature, each sample is washed and filtered with deionized water and then dried in an oven; then take out the powder of each group of samples for button cell preparation. After the preparation is completed, conduct button cell capacity testing to obtain the button cell specific capacity of each group of cathode material samples after the reaction; collect and organize the obtained button cell specific capacity data of each group, and calculate the capacity loss of each cathode material after soaking in various solvents.

[0012] Preferably, the synchronous reaction device includes a base, a main pipe is buried on one side of the base, a translation mechanism is provided on the base, a motor and a hollow column are provided on the translation mechanism, an installation ring is fixedly provided outside the hollow column through a bracket, a plurality of liquid injection pipes are communicated with the outer wall of the installation ring, the heights of the plurality of liquid injection pipes decrease continuously, a ring groove is provided at the lower part of the outer wall of the installation ring, a window is provided on the ring groove, a connecting pipe is communicated between the inner wall of the installation ring and the hollow column, a liquid outlet groove is provided at the bottom of the installation ring, a plug is provided in the liquid outlet groove, an annular groove is slidably connected in the installation ring, a plurality of partition plates are uniformly arranged along the circumferential direction in the annular groove, the annular groove is separated into a plurality of reaction chambers by the partition plates, a plurality of liquid injection holes are provided on the outer wall of the annular groove, the heights of adjacent liquid injection holes decrease continuously, the heights of two liquid injection holes at equal intervals are the same, the interval is N - 1 liquid injection holes, N is the total number of liquid injection pipes, the liquid injection holes are periodically communicated with the liquid injection pipes at the same height, a plurality of connecting holes are provided on the inner wall of the annular groove, the connecting holes are periodically communicated with the connecting pipe, a plurality of liquid outlet holes are provided at the bottom of the annular groove, the liquid outlet holes are periodically communicated with the liquid outlet groove, a filter screen is provided on each liquid outlet hole, a liquid injection hole, a connecting hole and a liquid outlet hole are provided in each reaction chamber, a gear ring is provided at the lower part of the outer wall of the annular groove, the gear ring is arranged in the ring groove, a gear is provided on the output shaft of the motor, the gear is meshed with the gear ring at the window, a lifting mechanism is rotatably connected to the top of the hollow column, an annular sealing plate is hung under the lifting mechanism, the annular sealing plate is in sealing contact with the top of the annular groove and the partition plates, and a heat preservation box is provided outside the lifting mechanism and the installation ring.

[0013] Preferably, the translation mechanism includes a sliding groove provided on the base, a substrate is slidably connected in the sliding groove, a first screw is rotatably connected between the two ends of the sliding groove, the substrate is threadedly connected with the first screw, and the motor and the hollow column are both provided on the substrate.

[0014] Preferably, the lifting mechanism includes a hollow lifting column rotatably connected to the top of the hollow column, a cross bar is slidably connected in the hollow lifting column, the annular sealing plate is hung at both ends of the cross bar, through grooves are provided on both sides of the hollow lifting column, the cross bar extends out of the through grooves and is slidably connected with the through grooves, a second screw is rotatably connected between the top and the bottom of the hollow lifting column, the second screw is threadedly connected with the middle part of the cross bar, and the upper end of the second screw penetrates through the top of the hollow lifting column and is provided with a turning handle.

[0015] The advantages of the present invention are as follows:

[0016] With the aid of the synchronous reaction device, the detection method of the present invention is easy to operate, has obvious effects, high contrast, and short experimental time, which is of great significance for evaluating and screening cathode materials. The synchronous reaction device can quickly and synchronously mix and react dozens of experimental samples, without the problems of sample mismatch and omission and excessive time consumption during manual preparation. The preparation time difference between experimental samples in the same batch is greatly reduced, which is especially suitable for the detection and exploration of a large number of samples, effectively improving the detection and screening efficiency. In addition, the reliability of the detection and screening results can be effectively improved. When the same sample combination is repeatedly detected, the detection results between different detection batches have small differences. Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the overall structure of the synchronous reaction device.

[0018] Figure 2 and Figure 3 It is a schematic diagram of the overall structure of the synchronous reaction device after removing the incubator.

[0019] Figure 4 It is a top view of the synchronous reaction device after removing the incubator.

[0020] Figure 5 is Figure 4 the sectional view taken along the line A-A in

[0021] Figure 6 is Figure 4 the sectional view taken along the line B-B in

[0022] Figure 7 It is a schematic diagram of the internal structure of the synchronous reaction device.

[0023] Wherein, 1 - base, 11 - chute, 12 - substrate, 13 - first screw, 14 - main pipe, 2 - hollow column, 21 - hollow lifting column, 211 - cross bar, 212 - second screw, 213 - turning handle, 214 - through groove, 22 - connecting pipe, 3 - mounting ring, 31 - window, 32 - liquid injection pipe, 33 - ring groove, 4 - annular groove, 41 - gear ring, 42 - partition plate, 43 - liquid injection hole, 44 - liquid outlet hole, 45 - connecting hole, 5 - motor, 51 - gear, 6 - annular sealing plate, 7 - liquid outlet groove, 71 - plug, 9 - incubator.

[0024] Figure 8 It is the comparison of the coin cell specific capacity between the control group and Samples 1 - 21.

[0025] Figure 9 It is the distribution of the capacity attenuation of LFP1 - 7 after soaking in the solvent. Detailed Embodiments

[0026] In order to make the technical means, creative features, achieved objectives and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0027] Example 1: In order to synchronously and quickly mix the solid powder of the reaction cathode material and the liquid solvent, in this example, a synchronous reaction device is used to prepare experimental samples of multiple groups. The structure of the synchronous reaction device is as Figures 1 to 7 shown, including a base 1. A main pipe 14 is buried on one side of the base 1. A chute 11 is provided on the base 1. A substrate 12 is slidably connected in the chute 11. A first screw 13 is rotatably connected between the two ends of the chute 11. The substrate 12 is threadedly connected to the first screw 13. A motor 5 and a hollow column 2 are provided on the substrate 12. An installation ring 3 is fixedly provided on the outside of the hollow column 2 through a bracket. A total of three liquid injection pipes 32 are communicated on the outer wall of the installation ring 3. The heights of the three liquid injection pipes 32 decrease continuously. A ring groove 33 is provided at the lower part of the outer wall of the installation ring 3. A window 31 is opened on the ring groove 33. A connecting pipe 22 is communicated between the inner wall of the installation ring 3 and the hollow column 2. An out-let groove 7 is provided at the bottom of the installation ring 3. A plug 71 is provided in the out-let groove 7. An annular groove 4 is slidably connected in the installation ring 3. A plurality of partition plates 42 are uniformly arranged along the circumferential direction in the annular groove 4. The partition plates 42 divide the annular groove 4 into a plurality of reaction chambers. A plurality of liquid injection holes 43 are provided on the outer wall of the annular groove 4. The heights of adjacent liquid injection holes 43 decrease continuously. The heights of two liquid injection holes 43 at equal intervals are the same. The interval is two liquid injection holes 43. The liquid injection holes 43 are periodically communicated with the liquid injection pipes 32 at the same height. A plurality of connecting holes 45 are provided on the inner wall of the annular groove 4. The connecting holes 45 are periodically communicated with the connecting pipe 22. A plurality of out-let holes 44 are provided at the bottom of the annular groove 4. The out-let holes 44 are periodically communicated with the out-let groove 7. A filter screen is provided on each out-let hole 44. One liquid injection hole 43, one connecting hole 45 and one out-let hole 44 are provided in each reaction chamber. A gear ring 41 is provided at the lower part of the outer wall of the annular groove 4. The gear ring 41 is arranged in the ring groove 33. A gear 51 is provided on the output shaft of the motor 5. The gear 51 is engaged with the gear ring 41 at the window 31. A lifting mechanism is rotatably connected to the top of the hollow column 2. An annular sealing plate 6 is hung under the lifting mechanism. The annular sealing plate 6 is in sealing contact with the top of the annular groove 4 and the partition plates 42. A heat preservation box 9 is provided outside the lifting mechanism and the installation ring 3. The inner side of the heat preservation box 9 is open for the translation of the installation ring 3. A vertical curtain is provided on the inner side of the heat preservation box 9 for heat preservation. The total number of the liquid injection pipes 32 is the same as the number of types of solvents. Only one type of solvent is introduced into one liquid injection pipe 32.

[0028] In this embodiment, the lifting mechanism includes a hollow lifting column 21 rotatably connected to the top of the hollow column 2. A cross bar 211 is slidably connected inside the hollow lifting column 21. The annular sealing plate 6 is hung under both ends of the cross bar 211. Through grooves 214 are formed on both sides of the hollow lifting column 21. The cross bar 211 extends out of the through grooves 214 and is slidably connected to the through grooves 214. A second screw 212 is rotatably connected between the top and the bottom of the hollow lifting column 21. The second screw 212 is threadedly connected to the middle of the cross bar 211. The upper end of the second screw 212 passes through the top of the hollow lifting column 21 and is provided with a turning handle 213.

[0029] The following method is used to screen the cathode materials with high compatibility with the electrolyte. The specific operation steps are as follows:

[0030] S1. The lithium iron phosphate cathode materials to be detected are numbered as LFP1, LFP2, LFP3, LFP4, LFP4, LFP5, LFP6, LFP7 respectively. The three solvents are deionized water (solvent 1), electrolyte with a certain ratio (solvent 2), and pure electrolyte (solvent 3); Solvent 2 is a mixed solution formed by mixing the electrolyte and water in a ratio of 98%:2% (V / V).

[0031] S2. Take 300 g of each lithium iron phosphate cathode material and divide it into three equal parts, each part being 100 g. Add them to adjacent reaction chambers respectively. Then add the above three solvents to the reaction chambers. The added weight is 2-3 times that of the lithium iron phosphate cathode material to ensure that each lithium iron phosphate is mixed with each solvent. The specific method is as follows:

[0032] The injection pipe 32 is connected to each liquid storage tank through a hose in advance. The liquid storage tanks are respectively filled with solvents 1 to 3. The outer port of the main pipe 14 is connected to a vacuum pump. Rotate screw 13 to completely translate the substrate 12 and the hollow column 2 and motor 5 thereon out of the heat preservation box 9, rotate screw 212 to lift cross bar 211, cross bar 211 lifts annular sealing plate 6, and loads an equal amount of positive electrode material powder to be tested into each reaction chamber. The positive electrode materials of every three consecutive reaction chambers are the same. After filling, reverse screw 212 to lower annular sealing plate 6 until the annular sealing plate 6 is sealed against the top of the annular groove 4 and the partition 42. At this time, each reaction chamber is sealed and separated, and screw 13 is rotated in the opposite direction to translate the substrate 12 and the components thereon into the heat preservation box 9. When the opening at the bottom of the hollow column 2 is aligned and connected with the upper opening of the main pipe 14, stop rotating screw 13, turn on motor 5, motor 5 drives gear 51 to rotate, and gear 51 drives gear ring 41 and annular groove 4 to rotate. At the same time, the annular groove 4 drives the annular sealing plate 6, the cross bar 211 and the hollow lifting column 21 and other structures to rotate around the hollow column 2. When the annular groove 4 rotates to the point where the connecting hole 45 on the inner wall is connected to the connecting pipe 22, the vacuum pump is turned on. The vacuum pump extracts the air in the reaction chamber through the hollow column 2, the connecting pipe 22 and the connecting hole 45, and a negative pressure is formed in the reaction chamber. As the annular groove 4 rotates, the connecting hole 45 is staggered with the connecting pipe 22, and the reaction chamber is closed to maintain the negative pressure. The next connecting hole 45 is repeatedly connected with the connecting pipe 22 to continuously evacuate the reaction chamber. As the annular groove 4 continues to rotate, the injection hole 43 is connected with the injection pipe 32 at the same height. Under the action of negative pressure, the corresponding solvent is sucked into the reaction chamber. Subsequently, the injection hole 43 is staggered with the injection pipe 32 and disconnected, and the injection hole 43 is closed by the outer wall of the mounting ring 3. The height of the injection hole 43 of the subsequent reaction chamber gradually decreases or gradually increases, and it will only be connected to the injection tube 32 at the same height, so as to accept the injection of different solvents. Taking the present embodiment as an example, the first reaction chamber will only be connected to the lowest injection tube 32, and solvent 1 will be injected. The second reaction chamber will only be connected to the middle-high injection tube 32, and solvent 2 will be injected. The third reaction chamber will only be connected to the highest injection tube 32, and solvent 3 will be injected. The fourth reaction chamber will only be connected to the lowest injection tube 32, and solvent 1 will be injected. The fifth reaction chamber will only be connected to the middle-high injection tube 32, and solvent 2 will be injected. The sixth reaction chamber will only be connected to the highest injection tube 32, and solvent 3 will be injected. ..., and the cycle is repeated. The 1st to 3rd reaction chambers are all filled with positive electrode material LFP1, and the 4th to 6th reaction chambers are all filled with positive electrode material LFP2, and so on. In this way, multiple different solid-liquid reaction samples can be quickly matched and mixed by rotating the annular groove 4. When there are four types of solvents, the first to fourth reaction chambers contain the same positive electrode material, the fifth to eighth reaction chambers contain another positive electrode material, and so on. The cycle height variation of the injection hole 43 is also in units of four.

[0033] After the solid-liquid sampling in the annular groove 4 is completed, stop the motor 5, turn off the vacuum pump, stop rotating the annular groove 4, and close the liquid injection pipe 32. Let it stand for 2 h, then open the incubator 9, keep the constant temperature at 60 °C, and react for 24 h. After the reaction is completed, rotate the second screw 212 to lift the annular sealing plate 6, open the annular groove 4, remove the plug 71, turn on the motor 5, and rotate the annular groove 4. When the liquid outlet hole 44 passes through the liquid outlet groove 7, the liquid will filter out through the liquid outlet hole 44 and the liquid storage tank. Finally, the remaining solid powder in each reaction chamber continues to be dried. After drying, rotate the first screw 13, remove the annular groove 4 and the mounting ring 3, and take out the reacted cathode materials from the annular groove 4 respectively for subsequent treatment. After cleaning the annular groove 4, it can be used for the next detection test.

[0034] A total of 21 samples were obtained by the above mixing method, numbered as Sample 1 to Sample 21. Among them, the solvents of Sample 1, 4, 7, 10, 13, 16, and 19 are Solvent 1 (deionized water), the solvents of Sample 2, 5, 8, 11, 14, 17, and 20 are Solvent 2 (electrolyte with a certain ratio), and Sample 3, 6, 9, 12, 15, 18, and 21 are Reagent 3 (pure electrolyte).

[0035] S3. After the cathode materials obtained in step S2 are left to stand at room temperature, each sample is washed and filtered with deionized water 3 - 5 times, and then dried in an oven; then take out the sample powders of each group, carry out button cell preparation, and after preparation, carry out button cell capacity test to obtain the button cell specific capacity of the reacted cathode material samples of each group.

[0036] For the above seven lithium iron phosphate cathode materials, it is necessary to directly take out the lithium iron phosphate powder without soaking in the solvent to prepare the button cell of the control group and carry out specific capacity test.

[0037] S4. Collect and collate the obtained button cell specific capacity data of each group, calculate the capacity loss of each cathode material after soaking in various solvents, and the results are shown in Table 1 and Table 2 and Figure 8 and Figure 9 ;

[0038] Table 1 Detection results of button cell specific capacity (mAh / g) of the control group and Samples 1 - 21

[0039]

[0040] Table 2 Capacity decay results of LFP 1 - 7 after soaking in solvents

[0041]

[0042] Another by Figure 8 and Figure 9It can be seen that the capacity loss of LFP3 in the mixture of electrolyte and water and in pure electrolyte is the smallest. Thus, LFP3 can be screened out as the one with the best compatibility with the known electrolyte among the lithium iron phosphate cathode materials to be evaluated.

[0043] Control Example: The rest is the same as in Example 1, except that a synchronous reaction device is not used for the preparation of multi-group experimental samples, and all reaction samples are manually prepared, mixed, reacted, and dried.

[0044] The 21 sample combinations prepared in Example 1 and the control example were repeatedly prepared and detected 3 times, and the coefficient of variation was statistically analyzed to observe the screening stability of different detection batches.

[0045] Table 3 Statistical results of the coefficient of variation of different detection indexes in multi-batch detection

[0046]

[0047] Table 4 Statistical results of the time consumption of the cathode material samples after multiple preparation reactions

[0048]

[0049] The results in Table 3 and Table 4 show that the present invention uses a synchronous reaction device for sample preparation and in-situ reaction, which can not only prevent the mis-matching and omission of samples, but also effectively reduce the time for preparing samples after the reaction. In addition, due to the standardized automatic preparation by the synchronous reaction device, the detection results of the same sample combination fluctuate little under different batches, indicating that the preparation of samples after the reaction is more standard and uniform, which is conducive to improving the reliability of the detection method. Under manual operation conditions, the quality of the samples prepared after the reaction varies from person to person, and the long-term preparation operation will also lead to a decrease in the operation accuracy of people, and this defect cannot be eliminated. This defect becomes prominent when the number of samples is large. The present invention effectively overcomes this defect by using a synchronous reaction device.

[0050] As is known by common technical knowledge, the present invention can be implemented by other embodiments that do not depart from its spiritual essence or essential features. Therefore, the above-disclosed embodiments are illustrative in all aspects and not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are encompassed by the present invention.

Claims

1. A method for detecting a cathode material of a lithium-ion battery, characterized in that, it includes the following specific steps: S1. Number the lithium iron phosphate cathode material to be detected, and use deionized water, an electrolyte and water mixture with a certain ratio, and pure electrolyte as reaction solvents; S2. Divide each lithium iron phosphate cathode material into several equal parts on average, and fill them into a synchronous reaction device respectively. After sealing the synchronous reaction device, rotate the annular groove. During the rotation of the annular groove, various reaction solvents are periodically and repeatedly added to the lithium iron phosphate cathode material. The added weight of the reaction solvent is 2-3 times that of the lithium iron phosphate cathode material, so as to ensure that several different solid-liquid mixed reaction samples are prepared after mixing each lithium iron phosphate with each solvent; S3. After the solid-liquid mixed reaction samples are prepared, let them stand in situ in the annular groove for 2 h, and then keep the temperature constant at 60 °C and react for 24 h; S4. After the reaction is completed, rotate the annular groove to filter out the reaction solvents in the solid-liquid mixed reaction samples, and the remaining solids are dried and then taken out from the annular groove (4) respectively for subsequent treatment; S5. After the dried solids are placed at room temperature, wash and filter each sample with deionized water and dry it in an oven; then take out the powder of each group of samples, carry out button cell preparation, and after the preparation, carry out button cell capacity test to obtain the button cell specific capacity of each cathode material sample after reaction; collect and sort out the button cell specific capacity data obtained, and calculate the capacity loss of each cathode material soaked in various solvents.

2. The method for detecting a cathode material of a lithium-ion battery according to claim 1, characterized in that, The synchronous reaction device includes a base (1). A main pipe (14) is buried on one side of the base (1). A translation mechanism is provided on the base (1). A motor (5) and a hollow column (2) are provided on the translation mechanism. An installation ring (3) is fixedly provided outside the hollow column (2) through a bracket. A plurality of liquid injection pipes (32) are communicated with the outer wall of the installation ring (3). The heights of the plurality of liquid injection pipes (32) continuously decrease. A ring groove (33) is provided at the lower part of the outer wall of the installation ring (3). A window (31) is opened on the ring groove (33). A connecting pipe (22) is communicated between the inner wall of the installation ring (3) and the hollow column (2). An outliquid groove (7) is provided at the bottom of the installation ring (3). A plug (71) is provided in the outliquid groove (7). An annular groove (4) is slidably connected in the installation ring (3). A plurality of partition plates (42) are evenly arranged along the circumferential direction in the annular groove (4). The partition plates (42) divide the annular groove (4) into a plurality of reaction chambers. A plurality of liquid injection holes (43) are provided on the outer wall of the annular groove (4). The heights of adjacent liquid injection holes (43) continuously decrease. The heights of two liquid injection holes (43) with equal spacing are the same. The spacing is N - 1 liquid injection holes (43), where N is the total number of liquid injection pipes (32). The liquid injection holes (43) are periodically communicated with the liquid injection pipes (32) of the same height. A plurality of connecting holes (45) are provided on the inner wall of the annular groove (4). The connecting holes (45) are periodically communicated with the connecting pipe (22). A plurality of outliquid holes (44) are provided at the bottom of the annular groove (4). The outliquid holes (44) are periodically communicated with the outliquid groove (7). Each reaction chamber is provided with a liquid injection hole (43), a connecting hole (45), and an outliquid hole (44). A gear ring (41) is provided at the lower part of the outer wall of the annular groove (4). The gear ring (41) is arranged in the ring groove (33). A gear (51) is provided on the output shaft of the motor (5). The gear (51) is meshed with the gear ring (41) at the window (31). A lifting mechanism is rotatably connected to the top of the hollow column (2). An annular sealing plate (6) is hung under the lifting mechanism. The annular sealing plate (6) is in sealing contact with the top of the annular groove (4) and the partition plates (42). A heat preservation box (9) is provided outside the lifting mechanism and the installation ring (3).

3. The method for detecting a cathode material of a lithium - ion battery according to claim 2, characterized in that, the translation mechanism includes a chute (11) provided on the base (1). A substrate (12) is slidably connected in the chute (11). A first screw rod (13) is rotatably connected between the two ends of the chute (11). The substrate (12) is threadedly connected with the first screw rod (13). The motor (5) and the hollow column (2) are both provided on the substrate (12).

4. The method for detecting a cathode material of a lithium - ion battery according to claim 3, characterized in that, The lifting mechanism includes a hollow lifting column (21) rotatably connected to the top of the hollow upright column (2). A cross bar (211) is slidably connected inside the hollow lifting column (21). The annular sealing plate (6) is hung under both ends of the cross bar (211). Through grooves (214) are formed on both sides of the hollow lifting column (21). The cross bar (211) extends out from the through grooves (214) and is slidably connected to the through grooves (214). A second screw (212) is rotatably connected between the top and the bottom of the hollow lifting column (21). The second screw (212) is threadedly connected to the middle of the cross bar (211). The upper end of the second screw (212) passes through the top of the hollow lifting column (21) and is provided with a turning handle (213).

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