Battery piece cleaning method

Abstract

The invention relates to a battery piece cleaning method which comprises the steps that the weight of a battery piece is measured, a first weight M1 is obtained, and the surface of the battery piece is not provided with borosilicate glass and phosphorosilicate glass; putting the battery piece into a first cleaning tank for cleaning; drying the battery piece; measuring the weight of the battery piece again to obtain a second weight M2; whether the difference value M1-M2 is larger than a first preset weight difference delta M1 or not is judged; if M1-M2 is greater than delta M1, reducing the content of the first cleaning medium in the first cleaning tank; if M1-M2 is smaller than or equal to delta M1, whether the difference value M1-M2 is smaller than a second preset weight difference delta M2 or not is judged; and if M1-M2 is smaller than delta M2, the content of the first cleaning medium in the first cleaning tank is increased. In the application, since the surface of the battery piece does not have borosilicate glass and phosphorosilicate glass, the weight loss of the battery piece in the first cleaning tank is large, and the difference value M1-M2 can better reflect the cleaning effect of the first cleaning tank, so that whether the content of the first cleaning medium in the first cleaning tank is in a proper range or not can be judged.

Description

Technical Field

[0001] The present application relates to the technical field of battery cell production, and in particular to a battery cell cleaning method. Background Art

[0002] Solar cells can directly convert solar radiation energy into electrical energy, mainly based on the photovoltaic effect of crystalline silicon, that is, when the photons of sunlight are absorbed by semiconductor crystalline silicon, electron-hole pairs are generated. When these electron-hole pairs reach the pn junction composed of p-type crystalline silicon and n-type crystalline silicon, they are separated to both sides of the pn junction by the junction electric field. When an external load is connected, photocurrent is formed and electrical energy is output.

[0003] In the process of preparing solar cell cells, it is often necessary to clean the cells in a cleaning tank. Since the weight change of the cells during the cleaning process is small, generally only 0.02g, it is difficult to judge the cleaning effect by the weight change of the cells, and thus it is impossible to adjust the cleaning medium content in the cleaning tank. Summary of the invention

[0004] The present application provides a method for cleaning a battery cell, which is used to solve the problem that it is difficult to judge the cleaning effect of the battery cell and thus difficult to adjust the content of the cleaning medium in the cleaning tank.

[0005] The present invention provides a method for cleaning a battery cell, comprising:

[0006] Measuring the weight of the cell to obtain a first weight M1, wherein the surface of the cell does not have borosilicate glass and phosphosilicate glass;

[0007] Putting the battery cell into a first cleaning tank for cleaning;

[0008] Drying the battery cell;

[0009] Measuring the weight of the battery cell again to obtain a second weight M2;

[0010] Determine whether a difference M1-M2 between the first weight M1 and the second weight M2 is greater than a first preset weight difference ΔM1;

[0011] If M1-M2>ΔM1, reducing the content of the first cleaning medium in the first cleaning tank;

[0012] If M1-M2≤ΔM1, determine whether the difference M1-M2 is less than the second preset weight difference ΔM2;

[0013] If M1-M2<ΔM2, the content of the first cleaning medium in the first cleaning tank is increased.

[0014] In a possible design, if M1-M2>ΔM1, the time the battery cell is in the first cleaning tank is shortened while reducing the content of the first cleaning medium in the first cleaning tank;

[0015] And / or, if M1-M2<ΔM2, then while increasing the content of the first cleaning medium in the first cleaning tank, the time the battery cell stays in the first cleaning tank is extended.

[0016] In a possible design, the first preset weight difference ΔM1 satisfies: 0.8 g ≤ ΔM1 ≤ 1.0 g; and / or the second preset weight difference ΔM2 satisfies: 0.6 g ≤ ΔM1 ≤ 0.8 g.

[0017] In a possible design, the first cleaning medium is sodium hydroxide.

[0018] In a possible design, after the step of: placing the battery cell in a first cleaning tank for cleaning, the method for cleaning the battery cell includes: placing the battery cell in a second cleaning tank for cleaning;

[0019] After the step of drying the battery cell, the method for cleaning the battery cell includes:

[0020] forming a passivation layer on the front and back sides of the cell, and performing screen printing and sintering;

[0021] After the difference M1-M2 satisfies: ΔM2≤M1-M2≤ΔM1, the battery cell cleaning method further includes:

[0022] Measuring the short-circuit current density J of the battery cell;

[0023] Determine whether the short-circuit current density J is greater than a preset short-circuit current density J1;

[0024] If J>J1, the content of the second cleaning medium in the second cleaning tank is adjusted and whether the second cleaning medium is contaminated is checked.

[0025] In a possible design, the preset short-circuit current density J1 satisfies: 1.6×10 -15 A / cm 2 ≤J1≤1.6×10 -13 A / cm 2 .

[0026] In a possible design, after the step of: placing the battery cell into a second cleaning tank for cleaning, the method for cleaning the battery cell includes: placing the battery cell into a third cleaning tank for cleaning;

[0027] If J>J1, while adjusting the content of the second cleaning medium in the second cleaning tank and checking whether the second cleaning medium is contaminated, the content of the third cleaning medium in the third cleaning tank is adjusted and the third cleaning medium is checked for contamination.

[0028] In a possible design, the second cleaning medium is hydrogen peroxide, and the third cleaning medium is hydrofluoric acid.

[0029] In a possible design, after the step of drying the battery cell, the method for cleaning the battery cell includes:

[0030] forming a passivation layer on the front and back sides of the cell, and performing screen printing and sintering;

[0031] Measuring the lifetime t of minority carriers on the battery cell;

[0032] Determine whether the minority carrier lifetime t is greater than a preset lifetime t1;

[0033] If t<t1, it is determined whether the difference M1-M2 between the first weight M1 and the second weight is greater than the first preset weight difference ΔM1.

[0034] In a possible design, the preset lifespan t1 satisfies: 1000 μs≤t1≤3000 μs.

[0035] In the present application, since the surface of the cell does not have borosilicate glass and phosphosilicate glass, the surface area of ​​the cell that can react with the first cleaning medium is large, and the mass loss of the cell is relatively large. The weight loss of the cell in the first cleaning tank can be obtained by calculating the difference between the first weight M1 and the second weight M2. Since the mass loss of the cell in the first cleaning tank is large, the difference M1-M2 can better reflect the cleaning effect of the first cleaning tank, and then it can be judged whether the content of the first cleaning medium in the first cleaning tank is within an appropriate range.

[0036] Specifically, when the difference M1-M2>ΔM1, it means that the content of the first cleaning medium in the first cleaning tank is relatively high, and the content of the first cleaning medium in the first cleaning tank should be appropriately reduced to prevent excessive cleaning of the battery cell and affect the performance of the battery cell. When the difference M1-M2<ΔM2, it means that the content of the first cleaning medium in the first cleaning tank is relatively low, and the content of the first cleaning medium in the first cleaning tank should be appropriately increased to prevent inadequate cleaning of the battery cell and affect the performance of the battery cell.

[0037] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1A schematic diagram of the structure of a solar cell in this application;

[0039] Figure 2 It is a schematic diagram of the structure of the cleaning system in this application;

[0040] Figure 3 This is a flow chart of the battery cell cleaning method provided in this application.

[0041] Reference numerals:

[0042] 1- Solar cell;

[0043] 11 - base;

[0044] 12-emitter;

[0045] 13- tunnel dielectric layer;

[0046] 14- doped conductive layer;

[0047] 15- first passivation layer;

[0048] 16- second passivation layer;

[0049] 17- a first electrode;

[0050] 18- a second electrode;

[0051] 2- Cleaning system;

[0052] 20-water washing tank;

[0053] 21-first cleaning tank;

[0054] 22-second cleaning tank;

[0055] 23- the third cleaning tank;

[0056] 24- fourth cleaning tank;

[0057] 25-Fifth cleaning tank.

[0058] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application. DETAILED DESCRIPTION

[0059] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0060] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0061] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0062] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0063] It should be noted that the directional words such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described at the angles shown in the accompanying drawings and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0064] Figure 1 The structure of a solar cell is shown. Figure 1 As shown, the solar cell 1 includes: a substrate 11, an emitter 12, a tunneling dielectric layer 13, a doped conductive layer 14, a first passivation layer 15, and a second passivation layer 16. The substrate 11 has a first surface and a second surface opposite to each other. The emitter 12 is arranged on the first surface, the first passivation layer 15 is arranged on the side of the emitter 12 away from the substrate 11, the tunneling dielectric layer 13 is arranged on the second surface, the doped conductive layer 14 is arranged on the side of the tunneling dielectric layer 13 away from the substrate 11, and the second passivation layer 16 is arranged on the side of the doped conductive layer 14 away from the substrate 11. In addition, the solar cell 1 also includes a first electrode 17 connected to the emitter 12 and a second electrode 18 connected to the doped conductive layer 14.

[0065] Among them, the substrate 11 and the emitter 12 can form a PN junction structure together. The tunneling dielectric layer 13 can serve as a tunneling layer for the majority carriers, and at the same time chemically passivate the substrate 11 to reduce the interface state. The doped conductive layer 14 can form a band bending, realize the selective transmission of carriers, and reduce the recombination loss of carriers. The first passivation layer 15 can passivate the surface of the emitter 12 away from the substrate 11, and the second passivation layer 16 can passivate the surface of the doped conductive layer 14 away from the substrate 11, thereby reducing the recombination speed of the carriers of the emitter 12 and the doped conductive layer 14, and improving the photoelectric conversion efficiency of the solar cell.

[0066] Specifically, the substrate 11 may be a P-type silicon substrate, the emitter 12 may be an N-type emitter, the P-type silicon substrate and the N-type emitter may together form a built-in electric field structure that functions as a PN junction, or the substrate 11 may be an N-type silicon substrate, and the emitter 16 may be a P-type emitter.

[0067] In addition, since the solar cell has a sheet-like structure, it is also called a cell. The front side of the cell is the light-receiving side of the cell, and the back side of the cell is the backlight side of the cell.

[0068] Furthermore, in the process of preparing solar cells, it is often necessary to clean the cell. For example, the doped conductive layer 14 is generally formed by first depositing a layer of intrinsic polysilicon on the cell by low pressure chemical vapor deposition (LPCVD), and then diffusing phosphorus to convert the intrinsic polysilicon layer into a phosphorus-doped polysilicon layer. In the above process, polysilicon will be coated on the front and both side edges of the cell, and phosphorus silicon glass will be formed on the front of the cell. In order to remove the polysilicon coated on the front and both side edges of the cell and the PSG on the front of the cell, the cell needs to be cleaned.

[0069] The present application provides a method for cleaning a battery cell, such as Figure 2 As shown, the cleaning system for cleaning the battery cells includes: a first cleaning tank 21, a second cleaning tank 22, a third cleaning tank 23 and a water washing tank 20, the first cleaning tank 21 has a first cleaning medium, the second cleaning tank 22 has a second cleaning medium, the third cleaning tank 23 has a third cleaning medium, a water washing tank 20 is arranged between the first cleaning tank 21 and the second cleaning tank 22, and a water washing tank 20 is also arranged between the second cleaning tank 22 and the third cleaning tank 23.

[0070] The first cleaning medium may be sodium hydroxide, which is a strong corrosive liquid for silicon and can react with the polysilicon on the surface of the cell. The water washing tank 20 between the first cleaning tank 21 and the second cleaning tank 22 can clean the first cleaning medium remaining on the surface of the cell. It is understandable that the first cleaning medium may also be other strong corrosive liquids for silicon. In addition to the first cleaning medium, the first cleaning tank 21 may also have other cleaning media for protecting the cell and improving the cleaning effect.

[0071] The second cleaning medium can be hydrogen peroxide, which can remove the reactants produced during the cleaning of the battery cell by the first cleaning medium. The water washing tank 20 between the second cleaning tank 22 and the third cleaning tank 23 can clean the second cleaning medium remaining on the surface of the battery cell. In addition to the second cleaning medium, the second cleaning tank 22 can also contain sodium hydroxide.

[0072] The third cleaning medium may be hydrofluoric acid, which can remove the oxide layer, borosilicate glass and phosphosilicate glass on the silicon wafer.

[0073] like Figure 3 As shown, the cleaning method of the battery cell includes:

[0074] T1: The weight of the battery cell is measured to obtain a first weight M1, and the surface of the battery cell does not have borosilicate glass and phosphosilicate glass.

[0075] In this step, the battery cell can be a battery cell after texturing, that is, a battery cell having only a substrate 11 .

[0076] S1: Put the battery cell into the first cleaning tank 21 for cleaning.

[0077] In this step, since the surface of the cell does not have borosilicate glass and phosphosilicate glass, the surface area of ​​the cell that can react with the first cleaning medium is large, and the mass loss of the cell is relatively large.

[0078] S4: Drying the battery cells.

[0079] T2: Measure the weight of the battery cell again to obtain a second weight M2.

[0080] T31: Determine whether the difference M1-M2 between the first weight M1 and the second weight M2 is greater than a first preset weight difference ΔM1;

[0081] If M1-M2>ΔM1, then T41: reduce the content of the first cleaning medium in the first cleaning tank 21;

[0082] If M1-M2≤ΔM1, then T32: determine whether the difference M1-M2 is less than the second preset weight difference ΔM2;

[0083] If M1 − M2 < ΔM2 , then T42 : increase the content of the first cleaning medium in the first cleaning tank 21 .

[0084] In this embodiment, the weight loss of the battery cell in the first cleaning tank 21 can be obtained by calculating the difference between the first weight M1 and the second weight M2. Since the mass loss of the battery cell in the first cleaning tank 21 is large, the difference M1-M2 can better reflect the cleaning effect of the first cleaning tank 21, and thus determine whether the content of the first cleaning medium in the first cleaning tank 21 is within an appropriate range.

[0085] Specifically, when the difference M1-M2>ΔM1, it means that the content of the first cleaning medium in the first cleaning tank 21 is relatively high, and the content of the first cleaning medium in the first cleaning tank 21 should be appropriately reduced to prevent excessive cleaning of the battery cell and affect the performance of the battery cell. When the difference M1-M2<ΔM2, it means that the content of the first cleaning medium in the first cleaning tank 21 is relatively low, and the content of the first cleaning medium in the first cleaning tank 21 should be appropriately increased to prevent inadequate cleaning of the battery cell and affect the performance of the battery cell.

[0086] In addition, by measuring the weight of the battery cell after drying, the weight loss of the battery cell 21 in the first cleaning tank 21 can be calculated more accurately.

[0087] More specifically, the first preset weight difference ΔM1 satisfies: 0.8g≤ΔM1≤1.0g; the second preset weight difference ΔM2 satisfies: 0.6g≤ΔM1≤0.8g. For example, ΔM1 may be 0.8g, 0.82g, 0.85g, 0.88g, 0.9g, 0.92g, 0.95g, 0.98g, 1.0g, etc., and ΔM2 may be 0.6g, 0.62g, 0.65g, 0.68g, 0.7g, 0.72g, 0.75g, 0.78g, 0.8g, etc.

[0088] The first preset weight difference ΔM1 should not be too large or too small. If the first preset weight difference ΔM1 is too large (for example, greater than 1.0g), the content of the first cleaning medium in the first cleaning tank 21 will be too high, resulting in excessive cleaning of the battery cell and affecting the performance of the battery cell. If the first preset weight difference ΔM1 is too small (for example, less than 0.8g), the range of the first preset weight difference ΔM1 to the second preset weight difference ΔM2 will be too small, making it difficult to adjust the content of the first cleaning medium in the first cleaning tank 21 to an appropriate range.

[0089] Similarly, the second preset weight difference ΔM2 should not be too large or too small. If the second preset weight difference ΔM2 is too large (for example, greater than 0.8g), the range of the first preset weight difference ΔM1 to the second preset weight difference ΔM2 will be too small, and it will be difficult to adjust the content of the first cleaning medium in the first cleaning tank 21 to an appropriate range; if the second preset weight difference ΔM2 is too small (for example, less than 0.6g), the content of the first cleaning medium in the first cleaning tank 21 will be too low, resulting in inadequate cleaning of the battery cell and affecting the performance of the battery cell.

[0090] It can be understood that the first preset weight difference ΔM1 and the second preset weight difference ΔM2 can be adjusted according to actual working conditions.

[0091] Furthermore, if M1-M2>ΔM1, the time the battery cell stays in the first cleaning tank 21 is shortened while reducing the content of the first cleaning medium in the first cleaning tank 21, thereby improving the cleaning efficiency of the battery cell without affecting the cleaning effect of the battery cell.

[0092] Similarly, if M1-M2<ΔM2, the time the battery cell stays in the first cleaning tank 21 is extended while increasing the content of the first cleaning medium in the first cleaning tank 21, thereby preventing the first battery cell from being difficult to clean due to the battery cell staying in the first cleaning tank 21 for a short time.

[0093] Furthermore, Figure 3 As shown, in step S4: after drying the battery cell, the battery cell cleaning method further includes:

[0094] S5: Form a passivation layer on the front and back of the cell, and perform screen printing and sintering.

[0095] In this step, the passivation layer on the front side of the cell is the first passivation layer 15, and the passivation layer on the back side of the cell is the second passivation layer 16. After screen printing and sintering, a first electrode 17 and a second electrode 18 are formed on the cell.

[0096] After the difference M1-M2 satisfies: ΔM2≤M1-M2≤ΔM1, the battery cell cleaning method further includes:

[0097] T5: Measure the short-circuit current density J of the battery cell.

[0098] Among them, the short-circuit current density J of the cell refers to the value of the short-circuit current density output by the cell under illumination conditions. When the short-circuit current density of the cell is high, it means that the recombination of electrons and holes is less, and the photoelectric conversion efficiency of the cell is higher. When the cleaning effect of the cleaning system is better, the recombination of the cell is less; when the cleaning effect of the cleaning system is poor, the recombination on the cell is more.

[0099] T6: Determine whether the short-circuit current density J is greater than the preset short-circuit current density J1;

[0100] If J>J1, then T7: adjust the content of the second cleaning medium in the second cleaning tank 22 and check whether the second cleaning medium is contaminated.

[0101] In this step, when the short-circuit current density J is greater than the preset short-circuit current density J1, it indicates that the recombination in the cell is high and the photoelectric conversion efficiency of the cell is low. When the content of the first cleaning medium in the first cleaning tank 21 is within a reasonable range, it is necessary to check whether the content of the second cleaning medium in the second cleaning tank 22 is within a reasonable range.

[0102] When the content of the second cleaning medium in the second cleaning tank 22 is low, it will be difficult for the second cleaning tank 22 to clean the reactants generated during the cleaning process of the battery cell by the first cleaning medium. When the content of the second cleaning medium in the second cleaning tank 22 is high, the battery cell will be over-cleaned, which will also affect the performance of the battery cell.

[0103] Specifically, the preset short-circuit current density J1 satisfies: 1.6×10 -15 A / cm 2 ≤J1≤1.6×10 -13 A / cm 2 For example, the preset short-circuit current density J1 may be: 1.6×10 -15 A / cm 2 , 3.6×10 -15 A / cm 2 , 5.6×10 -15 A / cm 2 , 8.6×10 -15 A / cm 2 , 1.6×10 -14 A / cm 2 , 3.6×10 -14 A / cm 2 , 5.6×10 -14 A / cm 2 , 8.6×10 -14 A / cm 2 , 1.6×10 -13 A / cm 2 wait.

[0104] The preset short-circuit current density J1 should not be too large or too small. If the preset short-circuit current density J1 is too large (for example, greater than 1.6×10 -13 A / cm 2 ), the adjustment of the second cleaning medium content in the second cleaning tank 22 will be out of the appropriate range, affecting the cleaning ability of the second cleaning tank 22; if the preset short-circuit current density J1 is too small (for example, less than 1.6×10 -16 A / cm 2 ), it will increase the difficulty of adjusting the content of the second cleaning medium in the second cleaning tank 22.

[0105] Preferably, if J>J1, while adjusting the content of the second cleaning medium in the second cleaning tank 22 and checking whether the second cleaning medium is contaminated, the content of the third cleaning medium in the third cleaning tank 23 is adjusted and checked whether the third cleaning medium is contaminated, thereby preventing high recombination in the battery cell due to the content of the third cleaning medium in the third cleaning tank 23 being out of an appropriate range or the third cleaning medium being contaminated.

[0106] Optionally, while adjusting the content of the second cleaning medium in the second cleaning tank 22 , the time the battery cell is in the second cleaning tank 22 may also be adjusted.

[0107] In addition, if Figure 2 As shown, the cleaning system for cleaning the battery cells also includes: a fourth cleaning tank 24 and a fifth cleaning tank 25 , a water washing tank 20 is arranged between the third cleaning tank 23 and the fourth cleaning tank 24 , and a water washing tank 20 is also arranged between the fourth cleaning tank 24 and the fifth cleaning tank 25 .

[0108] Among them, the water washing tank 20 between the third washing tank 23 and the fourth washing tank 24 can wash the third washing medium remaining on the surface of the battery cell. The washing medium in the fourth washing tank 24 can be sodium hydroxide and hydrogen peroxide to neutralize the third washing medium remaining on the surface of the battery cell and oxidize and remove the organic residue on the surface of the battery cell. The water washing tank 20 between the fourth washing tank 24 and the fifth washing tank 25 can wash the washing medium in the fourth washing tank 24 remaining on the surface of the battery cell. The washing medium in the fifth washing tank 25 can be hydrofluoric acid to neutralize the washing medium in the fourth washing tank 24 remaining on the surface of the battery cell and form a dehydrating surface.

[0109] Preferably, while adjusting the content of the second cleaning medium in the second cleaning tank 22 and checking whether the second cleaning medium is contaminated, the content of the cleaning medium in the fourth cleaning tank 24 and the fifth cleaning tank 25 can also be adjusted, and the cleaning medium in the fourth cleaning tank 24 and the fifth cleaning tank 25 can be checked whether they are contaminated.

[0110] Furthermore, if Figure 3 As shown, T8: measures the lifetime t of minority carriers on the battery cell.

[0111] In this step, the average time from the generation to the disappearance of minority carriers is called the minority carrier lifetime. The shorter the minority carrier lifetime, the lower the photoelectric conversion efficiency of the cell. That is, the minority carrier lifetime t can reflect the passivation effect when the passivation layer is formed on the front and back of the cell, and then reflect the cleaning effect of the cleaning system. When the cleaning effect is better, the passivation effect of the passivation layer is better; when the cleaning effect is poor, the passivation effect of the passivation layer is poor. The measurement of minority carrier lifetime t can be carried out by microwave photoconductivity attenuation method, quasi-steady-state photoconductivity method, surface photovoltage method and other methods.

[0112] T9: Determine whether the minority carrier lifetime t is greater than the preset lifetime t1;

[0113] If t<t1, then T31: determine whether the difference M1-M2 between the first weight M1 and the second weight is greater than the first preset weight difference ΔM1.

[0114] In this step, when the minority carrier lifetime t is less than the preset lifetime t1, it means that the photoelectric conversion efficiency of the battery cell is low and the cleaning system 2 needs to be adjusted; when the minority carrier lifetime t is greater than or equal to the preset lifetime t1, it means that the photoelectric conversion efficiency of the battery cell is high and the cleaning system does not need to be adjusted.

[0115] Specifically, the preset life t1 satisfies: 1000 μs≤t1≤3000 μs. For example, the preset life t1 may be 1000 μs, 1100 μs, 1200 μs, 1500 μs, 1600 μs, 1800 μs, 2000 μs, 2500 μs, 2800 μs, 3000 μs, etc.

[0116] The preset life t1 should not be too large or too small. If the preset life t1 is too small (for example, less than 1000μs), the cleaning system will be judged to be adjusted only when the cleaning effect of the cleaning system is very poor, which will lead to a lower production standard of the battery cells and a lower photoelectric conversion efficiency of some produced battery cells; if the preset life t1 is too large (for example, greater than 3000μs), the cleaning system will be judged to be adjusted when the cleaning effect of the cleaning system is still acceptable, which will lead to a higher production standard of the battery cells and affect the production efficiency of the battery cells.

[0117] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for cleaning a battery cell, characterized in that: The battery cell cleaning method comprises: Measuring the weight of the cell to obtain a first weight M1, wherein the surface of the cell does not have borosilicate glass and phosphosilicate glass; Placing the battery cell into a first cleaning tank (21) for cleaning; Drying the battery cell; Measuring the weight of the battery cell again to obtain a second weight M2; Determine whether a difference M1-M2 between the first weight M1 and the second weight M2 is greater than a first preset weight difference ΔM1; If M1-M2>ΔM1, reducing the content of the first cleaning medium in the first cleaning tank (21); If M1-M2≤ΔM1, determine whether the difference M1-M2 is less than the second preset weight difference ΔM2; If M1-M2<ΔM2, the content of the first cleaning medium in the first cleaning tank (21) is increased.

2. The method for cleaning a battery cell according to claim 1, characterized in that: If M1-M2>ΔM1, the time the battery cell is in the first cleaning tank (21) is shortened while reducing the content of the first cleaning medium in the first cleaning tank (21); And / or, if M1-M2<ΔM2, the time the battery cell stays in the first cleaning tank (21) is extended while increasing the content of the first cleaning medium in the first cleaning tank (21).

3. The method for cleaning a battery cell according to claim 1, characterized in that: The first preset weight difference ΔM1 satisfies: 0.8g≤ΔM1≤1.0g; And / or, the second preset weight difference ΔM2 satisfies: 0.6g≤ΔM1≤0.8g.

4. The method for cleaning a battery cell according to claim 1, characterized in that: The first cleaning medium is sodium hydroxide.

5. The method for cleaning a battery cell according to claim 1, characterized in that: After the step of placing the battery cell in a first cleaning tank (21) for cleaning, the battery cell cleaning method comprises: placing the battery cell in a second cleaning tank (22) for cleaning; After the step of drying the battery cell, the method for cleaning the battery cell includes: forming a passivation layer on the front and back sides of the cell, and performing screen printing and sintering; After the difference M1-M2 satisfies: ΔM2≤M1-M2≤ΔM1, the battery cell cleaning method further includes: Measuring the short-circuit current density J of the battery cell; Determine whether the short-circuit current density J is greater than a preset short-circuit current density J1; If J>J1, the content of the second cleaning medium in the second cleaning tank (22) is adjusted and it is checked whether the second cleaning medium is contaminated.

6. The method for cleaning a battery cell according to claim 5, characterized in that: The preset short-circuit current density J1 satisfies: 1.6×10 -15 A / cm 2 ≤J1≤1.6×10 -13 A / cm 2 .

7. The method for cleaning a battery cell according to claim 5, characterized in that: After the step of placing the battery cell in a second cleaning tank (22) for cleaning, the battery cell cleaning method comprises: placing the battery cell in a third cleaning tank (23) for cleaning; If J>J1, while adjusting the content of the second cleaning medium in the second cleaning tank (22) and checking whether the second cleaning medium is contaminated, the content of the third cleaning medium in the third cleaning tank (23) is adjusted and the third cleaning medium is checked for contamination.

8. The method for cleaning a battery cell according to claim 7, characterized in that: The second cleaning medium is hydrogen peroxide, and the third cleaning medium is hydrofluoric acid.

9. The method for cleaning a battery cell according to any one of claims 1 to 8, characterized in that: After the step of drying the battery cell, the method for cleaning the battery cell includes: forming a passivation layer on the front and back sides of the cell, and performing screen printing and sintering; Measuring the lifetime t of minority carriers on the battery cell; Determine whether the minority carrier lifetime t is greater than a preset lifetime t1; If t<t1, it is determined whether the difference M1-M2 between the first weight M1 and the second weight M2 is greater than the first preset weight difference ΔM1.

10. The method for cleaning a battery cell according to claim 9, characterized in that: The preset life span t1 satisfies: 1000 μs≤t1≤3000 μs.

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