Method for recovering performance of battery piece after acetic acid experiment

Abstract

The invention provides a method for recovering the performance of a battery piece after an acetic acid experiment. The method comprises the following steps: S1, preparing the battery piece after the acetic acid experiment; s2, the battery piece is put into a chain type light injection furnace for light injection treatment, and the treatment steps include S21, the battery piece is conveyed to a preheating area through a conveying belt, the preheating temperature is set to be 300-350 DEG C, and the battery piece is treated for 30-50 s at the temperature; s22, the battery piece is conveyed to a heating area through the conveying belt, the heating temperature is set to be 440-500 DEG C, and heating treatment is conducted for 30-50 s; s23, the battery piece is conveyed to a light injection area by the conveying belt, the heating temperature is set to be 500-600 DEG C, and heating treatment is conducted for 30-50 s; s3, carrying out laser-assisted sintering treatment on the battery piece after light injection treatment; and S4, testing the battery piece. According to the method, light injection treatment and laser sintering treatment are combined, the electrical performance is restored to the level before an acetic acid experiment through staged repair, the experiment loss is greatly reduced, the scrap cost is reduced, the process is compatible with an existing production line, and operation is convenient.

Description

Technical Field

[0001] The present invention relates to the field of crystalline silicon battery production, and in particular to a method for recovering battery performance after an acetic acid test. Background Art

[0002] The packaging materials (such as EVA film) in photovoltaic modules will gradually decompose in a hot and humid environment, releasing acetic acid. The accumulation of acetic acid inside the module will accelerate the oxidation and corrosion of the metal materials inside the battery (such as silver electrodes and aluminum back surface field), which will in turn cause an increase in series resistance, a decrease in fill factor, and ultimately lead to electrical performance degradation. At the same time, long-term exposure to acetic acid environment may also shorten battery life and affect system stability. Therefore, there will be acetic acid test experiments on the battery side. The acetic acid test experiment simulates the acetic acid environment to detect the degree of corrosion of key parts such as the battery metallized silicon contact points and solder ribbons, and then predict performance changes in actual use.

[0003] This can lead to a significant drop in the electrical performance of the cell after the acetic acid test. The average Rs increases by 3-5 times, and the FF decreases by 10%-20%. This also results in poor EL and reduced grid line adhesion. Cells that were previously Grade A before the test need to be downgraded to Grade D afterward, significantly reducing their selling price and causing significant waste for the cell.

[0004] Therefore, it is necessary to design a method for recovering the performance of battery cells after the acetic acid test to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for restoring the performance of a battery cell after an acetic acid test. By combining light injection treatment with laser sintering treatment, the electrical performance is restored to the level before the acetic acid test in stages, which greatly reduces experimental losses and scrap costs. The process is compatible with existing production lines and is easy to operate.

[0006] To achieve the above object, the present invention adopts the following technical solution: a method for recovering the performance of a battery cell after an acetic acid test, comprising the following steps:

[0007] S1: Prepare the battery cell after acetic acid experiment;

[0008] S2: Place the cell into a chain light injection furnace for light injection treatment. The treatment steps include:

[0009] S21: The conveyor belt transports the battery cells to the preheating zone. The preheating temperature is set at 300-350°C, and the battery cells are treated at this temperature for 30-50 seconds. At this temperature, the silver oxide generated during the acetic acid experiment is rapidly decomposed into silver in the high temperature environment. The chemical formula is 2Ag2O→4Ag+O2↑(Δ).

[0010] S22: The conveyor belt transports the cell to the heating zone, where the heating temperature is set at 440°C-500°C for 30-50 seconds. At this temperature, the acetic acid residue on the cell surface, especially around the grid lines, is decomposed and volatilized due to the acetic acid test.

[0011] S23: The conveyor belt transports the cell to the light injection zone, where the heating temperature is set to 500-600°C for 30-50 seconds. At this temperature, the glass layer at the silver-silicon contact interface begins to soften, allowing the glass to re-fuse and rearrange, refilling the glass cavities corroded by acetic acid. Simultaneously, light injection reduces some of the metal ions oxidized by acetic acid. Light injection can accelerate the reduction of metal ions and silver ions in the glass corroded by acetic acid, increasing conductivity.

[0012] S3: Perform laser-assisted sintering on the cells after light injection treatment;

[0013] S4: The battery cell is tested.

[0014] As a further improved technical solution of the present invention, step S1 includes:

[0015] S11: Select several qualified finished battery cells, test their electrical performance and record them;

[0016] S12: Prepare an acetic acid test solution, heat the solution to 80-90° C., and use the solution to fumigate the battery cells for 7-10 hours. The solution includes the following components in the following weight ratios: 60-65% deionized water, 30-40% potassium chloride, and 0.2-0.8% acetic acid;

[0017] S13: Retest the electrical performance of the battery cell after the acetic acid test and record the results.

[0018] As a further improved technical solution of the present invention, in step S2, the conveying speed of the battery cell is 10m / min-20m / min.

[0019] As a further improved technical solution of the present invention, in step S23, the light intensity is set to 2%-20% and the rated light intensity is 50-120 suns.

[0020] As a further improved technical solution of the present invention, step S2 further includes: S24: cooling the cell after the light injection process.

[0021] As a further improved technical solution of the present invention, in step S3, the laser deflection voltage is 12-20V, the laser power is 2%-60%, and the rated power is 60W-500W.

[0022] As a further improved technical solution of the present invention, in step S3, the laser is an infrared continuous laser or a blue laser, and the scanning speed is 10m / s-60m / s.

[0023] As a further improved technical solution of the present invention, in step S11, step S13 and step S4, an IV-EL integrated tester is used to test the battery cell.

[0024] As can be seen from the above technical solution, the method for restoring cell performance after the acetic acid test of the present invention can be accomplished sequentially through the following steps: first, the silver oxide on the gate line surface is decomposed into elemental silver, while simultaneously softening the glass layer in contact with the silver silicon, allowing the glass to re-fuse and rearrange, and removing the glass voids corroded by acetic acid; then, the cell surface is dried to decompose the residual acetic acid at high temperature; and simultaneously, light injection is used to reduce some of the metal ions oxidized by the acetic acid. Furthermore, laser-assisted sintering is used to completely reduce the oxidized metal ions to elemental silver. Simultaneously, the instantaneous high temperature of 2000°C-3000°C during the laser-assisted sintering, exceeding the melting point of silicon, regenerates new silver-silicon contacts at the silver-silicon interface, replacing those damaged in the acetic acid test and restoring the cell's electrical performance and EL. Furthermore, because the laser-assisted sintering of the micron-level contacts occurs at a momentary high temperature near the cell contact points, heat is quickly dissipated, preventing damage to the cell. By combining light injection treatment with laser sintering treatment, the electrical performance is restored to the level before the acetic acid test through staged repair, which greatly reduces experimental losses and scrap costs. The process is also compatible with existing production lines and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a photo of the electroluminescence test of the cell in Example 1 of the present invention before the acetic acid test.

[0026] Figure 2 This is a photo of the electroluminescence test of the cell in Example 1 after the acetic acid test.

[0027] Figure 3 This is a photo of the electroluminescence test of the cell in Example 1 after the performance recovery process. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Acetic acid experiment

[0030] S11: Select several qualified finished battery cells, test their electrical performance and record them;

[0031] S12: Prepare an acetic acid experimental solution, heat the solution to 85° C., and use the solution to fumigate the battery cells for 8.5 hours. The solution includes the following components in the following weight ratios: 61.2% deionized water, 38.4% potassium chloride, and 0.4% acetic acid;

[0032] S13: Retest the electrical performance of the battery cell after the acetic acid test and record the results.

[0033] Example 1

[0034] 100 cells were selected after completing the acetic acid experiment, and the average initial photoelectric conversion efficiency was 20.89%.

[0035] S21: The conveyor belt transports the battery cells to the preheating zone. The preheating temperature is set to 300°C, and the battery cells are treated at this temperature for 30 seconds.

[0036] S22: The conveyor belt transports the battery cell to the heating zone, the heating temperature is set to 440°C, and the heating process is carried out for 30 seconds;

[0037] S23: The conveyor belt transports the cell to the light injection area. The heating temperature is set to 500°C for 30 seconds. The light intensity is set to 2%. An LED light with a rated light intensity of 80 suns is selected for injection.

[0038] S3: Perform laser-assisted sintering on the cells after light injection treatment: Use an infrared continuous laser with a rated power of 60W, set the laser deflection voltage to 12V, the laser power to 50%, and the scanning speed to 10m / s to process the cells.

[0039] S4: Testing: After the treatment is completed, the cells are tested and the average photoelectric conversion efficiency is measured to be 25.31%.

[0040] Example 2

[0041] 100 cells were selected after completing the acetic acid experiment, and the average initial photoelectric conversion efficiency was 20.75%.

[0042] S21: The conveyor belt transports the battery cells to the preheating zone. The preheating temperature is set to 325°C, and the battery cells are treated at this temperature for 30 seconds.

[0043] S22: The conveyor belt transports the battery cell to the heating zone, the heating temperature is set to 470°C, and the heating process is carried out for 30 seconds;

[0044] S23: The conveyor belt transports the cell to the light injection area, the heating temperature is set to 550°C, the heating treatment is performed for 30 seconds, the light intensity is set to 10%, and the LED light with a rated light intensity of 80 suns is selected for injection;

[0045] S3: Perform laser-assisted sintering on the cells after light injection treatment: Use a blue laser with a rated power of 200W, set the laser deflection voltage to 16V, the laser power to 30%, and the scanning speed to 30m / s to process the cells.

[0046] S4: Testing: After the treatment is completed, the cells are tested and the average photoelectric conversion efficiency is measured to be 25.24%.

[0047] Example 3

[0048] 100 cells were selected after completing the acetic acid experiment, and the average initial photoelectric conversion efficiency was 20.69%.

[0049] S21: The conveyor belt transports the battery cells to the preheating zone. The preheating temperature is set to 350°C, and the battery cells are treated at this temperature for 30 seconds.

[0050] S22: The conveyor belt transports the battery cell to the heating zone, the heating temperature is set to 500°C, and the heating process is carried out for 40 seconds;

[0051] S23: The conveyor belt transports the cell to the light injection area. The heating temperature is set to 600°C for 40 seconds. The light intensity is set to 20%. LED light with a rated light intensity of 80 suns is selected for injection.

[0052] S3: Perform laser-assisted sintering on the cells after light injection treatment: Use a blue laser with a rated power of 200W, set the laser deflection voltage to 20V, the laser power to 60%, and the scanning speed to 60m / s to process the cells.

[0053] S4: Testing: After the processing is completed, the cells are tested and the average photoelectric conversion efficiency is measured to be 25.20% 。

[0054] Example 4

[0055] 100 cells were selected after completing the acetic acid experiment, and the average initial photoelectric conversion efficiency was 20.85%.

[0056] S21: The conveyor belt transports the battery cells to the preheating zone. The preheating temperature is set to 350°C, and the battery cells are treated at this temperature for 30 seconds.

[0057] S22: The conveyor belt transports the battery cell to the heating zone, the heating temperature is set to 500°C, and the heating process is carried out for 40 seconds;

[0058] S23: The conveyor belt transports the cell to the light injection area. The heating temperature is set to 600°C for 40 seconds. The light intensity is set to 20%. LED light with a rated light intensity of 80 suns is selected for injection.

[0059] S3: Perform laser-assisted sintering on the cells after light injection treatment: Use a blue laser with a rated power of 200W, set the laser deflection voltage to 20V, the laser power to 60%, and the scanning speed to 60m / s to process the cells.

[0060] S4: Testing: After the treatment is completed, the cells are tested, and the average photoelectric conversion efficiency is measured to be 25.05%.

[0061] Comparative Example 1

[0062] 100 cells were selected after the acetic acid experiment and no performance recovery treatment was performed. The average photoelectric conversion efficiency was 20.65%.

[0063] Comparative Example 2 (Light Injection Treatment Only)

[0064] 100 cells were selected after the acetic acid test, and the average initial photoelectric conversion efficiency was 20.71%. The treatment process was the same as in Example 2, but without the laser-assisted sintering treatment. After treatment, the average photoelectric conversion efficiency of the cells was 22.90%.

[0065] Comparative Example 3 (laser-assisted sintering process only)

[0066] 100 cells were selected after the acetic acid test, and the average initial photoelectric conversion efficiency was 20.76%. The treatment process was the same as in Example 2, but without the light injection treatment. After the treatment, the average photoelectric conversion efficiency of the cells was 21.13%.

[0067] Table 1 Photoelectric conversion efficiency data and change rate of the cells in each embodiment and comparative example before, after and after acetic acid test

[0068]

[0069] Table 2 Performance data of the battery cell in Example 1 before, after and after the acetic acid test

[0070]

[0071] Table 3 EL image analysis of the cell in Example 1 before, after and after acetic acid test

[0072]

[0073] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. The understanding of this specification should be based on those skilled in the art. Although this specification has described the present invention in detail with reference to the above embodiments, those skilled in the art should understand that those skilled in the art can still modify or make equivalent substitutions to the present invention, and all technical solutions and improvements thereof that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for restoring battery cell performance after an acetic acid test, characterized in that: The following steps are involved: S1: Prepare the battery cell after acetic acid experiment; S2: Place the cell into a chain light injection furnace for light injection treatment. The treatment steps include: S21: The conveyor belt transports the battery cells to the preheating zone. The preheating temperature is set to 300-350°C, and the battery cells are treated at this temperature for 30-50 seconds. S22: The conveyor belt transports the battery cell to the heating zone, the heating temperature is set to 440℃-500℃, and the heating process is carried out for 30-50s; S23: The conveyor belt transports the cell to the light injection area, the heating temperature is set to 500℃-600℃, and the heating process is carried out for 30-50s; S3: Perform laser-assisted sintering on the cells after light injection treatment; S4: The battery cell is tested.

2. The method for restoring battery cell performance after acetic acid testing according to claim 1, wherein: Step S1 includes: S11: Select several qualified finished battery cells, test their electrical performance and record them; S12: Prepare an acetic acid test solution, heat the solution to 80-90° C., and use the solution to fumigate the battery cells for 7-10 hours. The solution includes the following components in the following weight ratios: 60-65% deionized water, 30-40% potassium chloride, and 0.2-0.8% acetic acid; S13: Retest the electrical performance of the battery cell after the acetic acid test and record the results.

3. The method for restoring battery cell performance after acetic acid testing according to claim 1, wherein: In step S2, the conveying speed of the battery cell is 10m / min-20m / min.

4. The method for restoring battery cell performance after an acetic acid test according to claim 1, wherein: In step S23, the light intensity is set to 2%-20% and the rated light intensity is 50-120 suns.

5. The method for restoring battery cell performance after acetic acid testing according to claim 1, wherein: Step S2 also includes: S24: cooling the cell after the light injection process.

6. The method for restoring battery cell performance after an acetic acid test according to claim 1, wherein: In step S3, the laser deflection voltage is 12-20V, the laser power is 2%-60%, and the rated power is 60W-500W.

7. The method for recovering battery cell performance after acetic acid testing according to claim 6, wherein: In step S3, the laser is an infrared continuous laser or a blue laser, and the scanning speed is 10m / s-60m / s.

8. The method for restoring battery cell performance after an acetic acid test according to claim 2, wherein: In step S11, step S13 and step S4, the battery cell is tested using an IV-EL integrated tester.

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