Preparation process of BC battery

Abstract

The invention discloses a preparation process of a BC battery, which comprises the following steps: S1, preparing a first metal layer on the surface of an N electrode by a light induction process; s2, sequentially depositing a second metal layer, a barrier layer and a seed layer on the back surface of the battery piece by a vacuum deposition process; the material of the second metal layer is different from that of the first metal layer; s3, performing a patterning process on the back surface of the battery piece to expose a to-be-electroplated region; s4, preparing a metal grid line in the to-be-electroplated area through an electroplating process; and S5, removing the mask layer, the seed layer, the barrier layer and the second metal layer. Through the photoelectric induction technology, the nickel metal layer is prepared on the N electrode, the N face and the nickel metal form ohmic contact, the aluminum metal layer is prepared on the surface of the P electrode, the P face and the aluminum metal form ohmic contact, compounding of the metal contact face is reduced, the open voltage Voc of the battery piece is improved, ohmic contact resistance is reduced, and the short-circuit current Isc and the fill factor FF of the battery piece are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic cells, and in particular to a preparation process of a BC cell. Background Art

[0002] BC (Back Contact) battery is a photovoltaic cell based on organic semiconductor materials. It has high conversion efficiency and the characteristics of being a stacked battery. It is regarded as one of the important development directions of the future photovoltaic industry.

[0003] In the past, most of the metal grid lines of BC batteries were prepared by the current printing and coating of conductive silver paste. Although simple and easy, it loses some electrical gain, that is, because of the electrical loss of high resistivity silver paste when collecting carriers, that is, Rs is too high. In addition, since the metal grid line area of ​​existing BC batteries is greater than 15% or more, the cost of preparing conductive grid lines with conductive silver paste is high, making the manufacturing cost of BC batteries far higher than that of ordinary cells.

[0004] Another process is to use laser technology to pattern the passivation layer (silicon nitride layer) according to the fine line width of the metal gate line. Then the nickel layer is prepared by chemical deposition, or the aluminum metal layer or nickel metal layer is plated by PVD vacuum deposition process. Then the nickel-silicon alloy layer is formed by annealing process to obtain a good ohmic contact layer. However, these process flows are complicated, lengthy and all-round, and the same ohmic contact metal layer is prepared in the P / N region without distinction. For example, nickel metal is doped in the P region to form a composite and reduce the opening voltage of the cell; on the contrary, if aluminum is plated, an unmatched composite will be formed in the N region to reduce the opening voltage of the cell.

[0005] Therefore, both the traditional silver paste printing process and the currently introduced electroplating process are half-solutions. This is because the biggest feature of BC batteries is to move the electrode on the light-receiving side to the backlight side. This means that on the backlight side of the battery cell, both P and N electrodes coexist. Therefore, when applying an ohmic contact layer on it, the current process is to prepare the same surface without distinction. That is, to select full nickel metal or full aluminum metal deposition as the ohmic contact layer of the P / N electrodes on the same plane (the selection process that the P side should form an ohmic contact with the aluminum metal and the N side should form an ohmic contact with the nickel metal is not made). Doing it this way will increase the compounding of the metal contact area of ​​the battery, causing the battery's opening voltage (Voc) to decrease. Summary of the invention

[0006] In order to overcome the above disadvantages, the purpose of the present invention is to provide a BC battery preparation process, in which different metal layers are respectively arranged on the P side and the N side of the battery to reduce the opening voltage of the battery.

[0007] In order to achieve the above purpose, the technical solution adopted by the present invention is: a preparation process of a BC battery, comprising the following steps: S1, preparing a first metal layer on the surface of the N electrode by a light-induced process; S2. Depositing a second metal layer, a barrier layer and a seed layer in sequence on the back side of the cell by a vacuum deposition process; the material of the second metal layer is different from that of the first metal layer; S3, performing a patterning process on the back of the cell to expose the area to be electroplated; S4, preparing metal gate lines in the area to be electroplated by an electroplating process; S5, removing the mask layer, the seed layer, the barrier layer and the second metal layer.

[0008] Further, in S1, the material of the first metal layer is metal nickel, and the first metal layer and the N electrode form an ohmic contact.

[0009] Furthermore, in S1, the light-induced process operation process is: loading the battery cell with P / N electrodes into the light-induced electroplating equipment, so that a first metal layer with a thickness ranging from 0.01 to 5 um is deposited on the N electrode.

[0010] Furthermore, in S1, the electroplating solution includes nickel and boric acid, the concentration of nickel is 50-150 g / L, and the concentration of boric acid is 25-80 g / L; the temperature of the electroplating solution is 25°C~65°C.

[0011] Furthermore, in S1, the light-induced process time is 30-300 seconds, the light wavelength range is 200-600 nm, and the light intensity range is 20-70 mW / cm 2 .

[0012] Furthermore, in S2, the material of the second metal layer is metal aluminum, the thickness of the second metal layer is 5-200 nm, and the second metal layer forms an ohmic contact with the P electrode.

[0013] Further, in S2, the thickness of the barrier layer is 5-200 nm, and the material of the barrier layer is selected from any one or more of metal titanium, metal tungsten or alloys thereof.

[0014] Further, in S2, the thickness of the bottom seed layer is 10-300 nm, and the material of the bottom seed layer is selected from any one or more of metal copper, metal bismuth, metal gold, metal silver or alloys thereof.

[0015] Furthermore, in S2, the power of the vacuum deposition process is 1-10KW, and the time is 30-300 seconds.

[0016] Further, S4, copper metal grid lines are prepared by electroplating, the thickness of the copper metal grid lines is 5-50 um, and a tin protective layer electroplating deposition process is performed on the surface of the copper metal grid lines, and the thickness of the deposited tin protective layer is 1-5 um.

[0017] The beneficial effects of the present invention are: 1) In the present application, a nickel metal layer is prepared on the N electrode through a photoelectric induction process, and the N surface forms an ohmic contact with the nickel metal. An aluminum metal layer is prepared on the surface of the P electrode, and the P surface forms an ohmic contact with the aluminum metal, thereby reducing the recombination of the metal contact surface, increasing the opening voltage Voc of the battery cell, and reducing the ohmic contact resistance, thereby increasing the short-circuit current Isc and fill factor FF of the battery cell.

[0018] 2) By using mask patterning, fine-line metal grid lines are prepared to improve the bifacial power generation efficiency of BC batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 This is a schematic diagram of a battery cell having P / N electrodes prepared in the present invention; Figure 2 This is a schematic diagram of preparing the first metal layer on the surface of the N electrode according to the present invention; Figure 3 This is a schematic diagram of sequentially depositing a second metal layer, a barrier layer and a seed layer on the back of a cell according to the present invention; Figure 4 A schematic diagram of the patterning process for the back of the cell to expose the area to be electroplated according to the present invention; Figure 5 A schematic diagram of preparing metal grid lines in the area to be electroplated according to the present invention; Figure 6 A schematic diagram of removing the mask layer according to the present invention; Figure 7 It is a schematic diagram of the BC battery of the present invention.

[0022] 1. Battery cell; 2. N electrode; 3. P electrode; 4. First metal layer; 5. Second metal layer; 6. Barrier layer; 7. Seed layer; 8. Mask layer; 9. Area to be electroplated; 10. Metal grid line; 11. Tin protective layer. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0024] Except as shown in the operating examples or otherwise indicated, all numbers used in the specification and claims to indicate the amount of ingredients, physicochemical properties, etc. are understood to be adjusted by the term "about" in all cases. Therefore, unless otherwise indicated, the numerical parameters listed in the above specification and the attached claims are approximate values, and those skilled in the art can use the teachings disclosed herein to seek to obtain the desired properties and appropriately change these approximate values. The use of numerical ranges expressed as endpoints includes all numbers within the range and any range within the range, for example, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4 and 5, etc.

[0025] The applicant has found that when applying an ohmic contact layer on a battery cell (1), the current process is to prepare the same surface without distinction. That is, to select full nickel metal or full aluminum metal deposition as the ohmic contact layer of the P / N electrodes on the same plane (no selection process is made for the P electrode (3) to form an ohmic contact with the aluminum metal, and the N electrode (2) to form an ohmic contact with the nickel metal). Such a cheap approach actually increases the metal contact area of ​​the battery, resulting in a decrease in the battery's opening voltage (Voc).

[0026] Obviously, when the industry has successively introduced the process flow of BC batteries with full coverage of chemical deposition / vacuum deposition and electroplating, it has not recognized the contradictions of the existing process. A controllable and selective ohmic contact layer preparation process should be introduced to truly improve the final photoelectric conversion efficiency of BC batteries.

[0027] An embodiment of the present invention provides a BC battery preparation process to solve the above problems, which specifically includes the following steps: S1. See Appendix Figure 1 and attached Figure 2 As shown, a first metal layer (4) is prepared on the surface of the N electrode (2) by a light-induced process. The passivation layer on the prepared Poly-doped P / N electrode is subjected to a continuous or intermittent groove process by a dry etching process or a wet etching process, so as to expose the prepared Poly-doped P / N electrode for the subsequent preparation of the ohmic contact layer.

[0028] The cell having P / N electrodes is loaded into a light-induced electroplating device, and a first metal layer (4) with a thickness ranging from 0.01 to 5 μm is deposited on the N electrode (2) through a light-induced process. The material of the first metal layer (4) is preferably metal nickel.

[0029] The specific operating conditions of the photoinduced process are: the electroplating solution includes nickel and boric acid, the nickel concentration is 50-150g / L, the boric acid concentration is 25-80g / L; the electroplating solution temperature is 25℃~65℃. The photoinduced process time is 30~300 seconds, the temperature is 25℃~65℃, the light wavelength range is 200~600nm and the light intensity range is 20~70mW / cm 2 By limiting the operating conditions of the light-induced process, a nickel metal layer can be electroplated on the surface of the N electrode, while no nickel metal layer is deposited on the surface of the P electrode, making the deposition of the nickel metal layer regionally selective.

[0030] S2. See Appendix Figure 3 As shown, a second metal layer (5), a barrier layer (6) and a seed layer (7) are sequentially deposited on the back of a cell using a vacuum deposition process; the material of the second metal layer (5) is different from the material of the first metal layer (4).

[0031] In some embodiments, the power of the vacuum deposition process is 1-10 kW and the time is 30-300 seconds. By limiting the vacuum deposition process conditions, an adapted second metal layer (5), a barrier layer (6) and a seed layer (7) can be deposited on the back of the battery.

[0032] In some embodiments, the material of the second metal layer (5) is metal aluminum, and the thickness of the second metal layer (5) is 5-200 nm. The material of the second metal layer (5) is metal aluminum, which is different from the material of the first metal layer (4) (metal nickel). The aluminum layer of the second metal layer (5) is deposited on the surface of the P electrode, and the nickel layer of the first metal layer (4) is deposited on the surface of the N electrode. This can accurately adapt the ohmic contact metal layers with different P / N, thereby achieving the effect of truly reducing the ohmic contact resistance (Rs) and increasing the opening voltage (Voc) of the battery cell.

[0033] In some embodiments, the barrier layer (6) has a thickness of 5-200 nm, and the material is selected from metal titanium, metal tungsten or alloys thereof.

[0034] In some embodiments, the thickness of the bottom seed layer (7) is 10-300 nm, and the material is selected from metal copper, metal bismuth, metal gold, metal silver or alloys thereof.

[0035] In some embodiments, the first metal layer (4) and the second metal layer (5) may also be a metal alloy silicon layer prepared by PVD vacuum equipment. The temperature control range is 200°C to 650°C, and the heating time is 1 to 10 minutes.

[0036] S3. See Appendix Figure 4 As shown, a patterning process is performed on the back of the cell to expose the area to be electroplated (9); A dry mask material (commonly known as dry film) or a liquid mask material is used in combination with an exposure and development process to set a mask layer (8) on the back of the battery to expose the area of ​​the metal grid line (10) to be electroplated; the thickness of the mask layer (8) ranges from 10 to 50 um.

[0037] The mask drying temperature range is 70~150℃, and the drying time is 30~450 s.

[0038] The exposure conditions are 365nm or 405nm light source and exposure energy range is 15~350mJ / cm 2 Make an exposure.

[0039] The developer includes but is not limited to KOH with a concentration of 0.5-5% or NaOH with a concentration of 0.5-5%. The preferred operating conditions are temperature 25-28°C, time 30-60 seconds, and spraying pressure 2.0-2.5 Kg / cm 2 , exposing the area to be electroplated (9). The width of the opening formed ranges from 10 to 300 um.

[0040] In some embodiments, the patterned opening preparation process material can also be selected to be negative printing + drying to expose the area to be electroplated. The width of the formed opening ranges from 50 to 600 um.

[0041] S4. See Appendix Figure 5 As shown, a metal grid line (10) is prepared in the area to be plated (9) by an electroplating process. In some embodiments, the copper metal gate line (10) is prepared by electroplating using a copper sulfate system or a methanesulfonic acid system, and the thickness of the deposited copper metal gate line (10) ranges from 5 to 50 um.

[0042] In some embodiments, a tin protective layer (11) is electroplated and deposited on the surface of the copper metal grid line (10), and the deposited thickness ranges from 1 to 5 um. Tin has good electrical conductivity and is more active than copper, and can lose electrons preferentially. When tin is oxidized, a layer of tin dioxide (SnO2) is formed. This oxide layer can effectively prevent further oxidation of copper, thereby extending the service life of the battery.

[0043] The tin protective layer (11) can not only prevent the oxidation of the copper electrode, but also improve the overall stability of the battery. By plating tin on the surface of the copper electrode, the degradation of the electrode performance caused by copper oxidation can be reduced, ensuring the stable performance of the battery during long-term use.

[0044] S5, removing the mask layer (8), the seed layer (7), the barrier layer (6) and the second metal layer (5).

[0045] See attached Figure 6 As shown, removing the mask layer (8): the battery cell is transferred into the mask removal tank section for the mask removal process. The mask removal solution includes but is not limited to KOH with a concentration ratio of 0.5-5% or NaOH with a concentration ratio of 0.5-5%; the preferred operating conditions are a temperature of 45-50°C, a time of 120-150 seconds, and a spraying pressure of 0.5-2.5Kg / cm 2 , and remove the mask material.

[0046] See attached Figure 7 As shown, the seed layer (7) is removed: a copper seed layer etching process is performed, the etching solution is 2-5% dilute sulfuric acid, and the operation time is 120-230 seconds. The process operation conditions are room temperature and a spray pressure of 2.0-2.5 Kg / cm 2 , and etch the copper seed layer.

[0047] Removing the barrier layer (6): Performing a barrier layer etching process, the etching solution is 3~5% hydrogen peroxide H2O2. Process operating conditions: temperature 40-45°C, time 100~130 seconds, spray pressure 2.0~2.5 Kg / cm 2 , and the barrier layer is etched.

[0048] Removal of the second metal layer (5): Etching of the aluminum ohmic contact layer is performed with a concentration of 1-5% HF. Process operating conditions: temperature of 40-45°C, operating time of 120-130 seconds and spraying pressure of 2.0-2.5 Kg / cm 2 , the aluminum ohmic contact layer is etched away. After cleaning and drying, a BC cell with fine-line width metal grid lines, low string structure and high opening voltage is obtained.

[0049] Example The following examples describe the disclosure of the present invention in more detail, and these examples are intended for illustrative purposes only, as various modifications and variations within the scope of the disclosure of the present invention will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0050] Example 1 S1. Prepare the first metal layer on the surface of the N electrode by light-induced process The cells with P / N electrodes were loaded into the photoinduced electroplating equipment under the following operating conditions: nickel concentration 95±5g / L, boric acid concentration 27.5±2.5g / L, temperature 30±5 o C, time 55±5 seconds, light wavelength range 300±50nm and light intensity range 45±5mW / cm 2 A first metal layer with a deposition thickness of 2 um is deposited on the N electrode, and the first metal layer is a nickel metal layer, which is then cleaned and dried.

[0051] S2. Using vacuum deposition process, deposit the second metal layer, barrier layer and seed layer on the back of the cell in sequence The above-mentioned cell is loaded into a PVD vacuum deposition device, and a second metal layer with a thickness of 30 nm is sequentially deposited on the back of the cell, wherein the material of the second metal layer is metal aluminum. The specific operating conditions range is an operating power of 3KW and a time of 120 seconds.

[0052] The above cell is subjected to barrier layer deposition with a thickness of 80 nm, and the barrier layer is a titanium tungsten barrier metal layer. The specific operating conditions are: operating power 3KW, time 120 seconds.

[0053] The above-mentioned cell is subjected to copper seed layer deposition, the copper seed layer thickness is 100 nm, and the specific operating conditions range is operating power 5KW, time 100 seconds.

[0054] The battery cell is heated within a temperature range of 465±15° C. and a duration of 95±5 seconds.

[0055] S3. Perform a patterning process on the back of the cell to expose the area to be electroplated The above-mentioned battery cell is subjected to a fine line width patterning process, using a dry mask material (commonly known as dry film) in combination with an exposure and development process to expose the metal grid line area to be plated, forming a P electrode opening width of 40um and an N electrode opening width of 20um in the area to be plated, and the mask layer thickness range is 25um.

[0056] The developer is KOH with a concentration of 0.5%, the operating temperature is 25°C, the time is 60 seconds, and the spraying pressure is 2.0Kg / cm 2 .

[0057] S4. Preparing metal gate lines in the area to be plated by electroplating Through the electroplating process, a copper metal gate line with a thickness of 15 um is electroplated and deposited at the P electrode area and the N electrode pattern opening respectively.

[0058] Through the electroplating process, a tin protective layer with a thickness of 3 um is formed on the P-electrode and N-electrode copper metal grid lines respectively.

[0059] S5, removing the mask layer, the seed layer, the barrier layer and the second metal layer.

[0060] Remove the mask layer, and transfer the cell into the mask removal tank for mask removal process. The operating temperature range is 50±5℃. The operating spray pressure range is 0.5 Kg / cm 2 The defilming solution is KOH with a concentration of 1.5%, and the operation time is 120 seconds.

[0061] Seed layer removal: copper seed layer etching process, concentration is 5% dilute sulfuric acid. Process operating conditions: temperature is room temperature, time is 120 seconds and spray pressure is 2.5 Kg / cm 2 , and etch the copper seed layer.

[0062] Removal of barrier layer: titanium tungsten layer etching process, concentration of 3% hydrogen peroxide. Process operating conditions: temperature 45 ° C, time 120 seconds, spray pressure 2.5 Kg / cm 2 , and etch the barrier layer titanium tungsten layer.

[0063] Removal of the second metal layer: Etching of the aluminum ohmic contact layer was performed with a concentration of 1% HF. Process operating conditions: temperature 45°C, operating time 120 seconds and spray pressure 2.5 Kg / cm 2 , the second metal layer aluminum ohmic contact layer is etched away. After cleaning and drying, a BC cell with fine-line width metal grid lines, low string structure and high opening voltage is obtained.

[0064] Example 2 S1. Prepare the first metal layer on the surface of the N electrode by light-induced process The cells with P / N electrodes were loaded into the photoinduced electroplating equipment under the following operating conditions: nickel concentration 65±5g / L, boric acid concentration 27.5±2.5g / L, temperature 30±5 o C, time 35±5 seconds, light wavelength range 300±50nm and light intensity range 45±5mW / cm 2A first metal layer with a thickness of 0.5 um is deposited on the N electrode, and the first metal layer is a nickel metal layer, which is then cleaned and dried.

[0065] S2. Using vacuum deposition process, deposit the second metal layer, barrier layer and seed layer on the back of the cell in sequence The above-mentioned cell is loaded into a PVD vacuum deposition device, and a second metal layer with a thickness of 40 nm is sequentially deposited on the back of the cell, and the material of the second metal layer is metal aluminum. The specific operating conditions range is an operating power of 3KW and a time of 120 seconds.

[0066] The above cell is subjected to barrier layer deposition with a thickness of 120 nm, and the barrier layer is a titanium barrier metal layer. The specific operating conditions are: operating power 3KW, time 120 seconds.

[0067] The above-mentioned cell is subjected to copper seed layer deposition, the copper seed layer thickness is 100 nm, and the specific operating conditions range is operating power 5KW, time 100 seconds.

[0068] The battery cell is heated within a temperature range of 315±15° C. and a duration of 160±10 seconds.

[0069] S3, performing a patterning process on the back of the cell to expose the area to be electroplated; The above-mentioned battery cell is subjected to a direct printing patterning process to form a plating area with a P electrode opening width of 300um and an N electrode opening width of 180um, and the mask layer thickness range is 35um.

[0070] S4. Preparing metal gate lines in the area to be plated by electroplating Through the electroplating process, a copper metal gate line with a gate line thickness of 28 um is electroplated and deposited at the P electrode area and the N electrode pattern opening respectively.

[0071] Through the electroplating process, a tin protective layer with a thickness of 4 um is formed on the P-electrode and N-electrode copper metal grid lines respectively.

[0072] S5, removing the mask layer, the seed layer, the barrier layer and the second metal layer.

[0073] After removing the mask layer, the cell is transferred into the mask removal tank for mask removal process. The operating temperature range is 50°C. The operating spray pressure range is 0.5 Kg / cm 2 The defilming solution is KOH with a concentration of 1.5%, and the operation time is 230 seconds.

[0074] Seed layer removal: copper seed layer etching process, concentration is 5% dilute sulfuric acid. Process operating conditions: temperature is room temperature, time is 120 seconds and spray pressure is 2.5 Kg / cm 2, and etch the copper seed layer.

[0075] Removal of barrier layer: titanium layer etching process, concentration of 5% hydrogen peroxide. Process operating conditions: temperature 45 ° C, time 100 seconds, spray pressure 2.5 Kg / cm 2 , and etch the barrier titanium layer.

[0076] Removal of the second metal layer: Etching of the aluminum ohmic contact layer was performed with a concentration of 3% HF. Process operating conditions: temperature 45°C, operating time 120 seconds and spray pressure 2.5 Kg / cm 2 , the second metal layer aluminum ohmic contact layer is etched away. After cleaning and drying, a BC cell with fine-line width metal grid lines, low string structure and high opening voltage is obtained.

[0077] Comparative Example 1 The process steps for preparing BC batteries in Comparative Example 1 and Example 1 are basically the same. The main difference is that Comparative Example 1 does not prepare the first metal layer (nickel layer) on the surface of the N electrode through a photoinduced process, that is, the comparative example does not perform step 1 in Example 1, and directly deposits the second metal layer (aluminum layer) on the back of the battery cell.

[0078] Experimental Examples The BC batteries prepared in Examples 1-2 and Comparative Example 1 were subjected to performance tests, and the test results are shown in Table 1:

[0079] From the experimental data in Table 1, it can be seen that the present application uses a photoelectric induction process to prepare a nickel metal layer on the N electrode and an aluminum metal layer on the P electrode surface, thereby reducing the recombination of the metal contact surface and increasing the Voc of the cell, which increases the cell opening voltage by 18%. The ohmic contact resistance is reduced, and the Isc and FF of the cell are increased. By using mask patterning, fine-line metal grid lines are prepared to improve the bifacial power generation rate of the BC cell.

[0080] The present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, change of structural morphology, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0081] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0082] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0083] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

[0084] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for preparing a BC battery, characterized in that: The following steps are involved: S1, preparing a first metal layer on the surface of the N electrode by a light-induced process; S2. Depositing a second metal layer, a barrier layer and a seed layer in sequence on the back side of the cell by a vacuum deposition process; the material of the second metal layer is different from that of the first metal layer; S3, performing a patterning process on the back of the cell to expose the area to be electroplated; S4, preparing metal gate lines in the area to be electroplated by an electroplating process; S5, removing the mask layer, the seed layer, the barrier layer and the second metal layer.

2. The preparation process of the BC battery according to claim 1, characterized in that: In S1, the material of the first metal layer is nickel, and the first metal layer forms an ohmic contact with the N electrode.

3. The preparation process of the BC battery according to claim 1, characterized in that: In S1, the light-induced process operation process is: loading the battery cell with P / N electrodes into the light-induced electroplating equipment, so that a first metal layer with a thickness ranging from 0.01 to 5 um is deposited on the N electrode.

4. The preparation process of the BC battery according to claim 3, characterized in that: In S1, the electroplating solution includes nickel and boric acid, the concentration of nickel is 50-150 g / L, and the concentration of boric acid is 25-80 g / L; the temperature of the electroplating solution is 25°C~65°C.

5. The preparation process of the BC battery according to any one of claims 1 to 4, characterized in that: In S1, the photoinduced process time is 30~300 seconds, the light wavelength range is 200~600nm, and the light intensity range is 20~70mW / cm 2 .

6. The preparation process of the BC battery according to claim 1, characterized in that: In S2, the material of the second metal layer is metal aluminum, and the thickness of the second metal layer is 5-200 nm.

7. The process for preparing a BC battery according to claim 1, characterized in that: In S2, the thickness of the barrier layer is 5-200 nm, and the material of the barrier layer is selected from any one or more of metal titanium, metal tungsten or alloys thereof.

8. The process for preparing a BC battery according to claim 1, characterized in that: In S2, the thickness of the bottom seed layer is 10-300 nm, and the material of the bottom seed layer is selected from any one or more of metal copper, metal bismuth, metal gold, metal silver or alloys thereof.

9. The preparation process of the BC battery according to claim 1, characterized in that: In S2, the power of the vacuum deposition process is 1~10KW, and the time is 30~300 seconds.

10. The process for preparing a BC battery according to claim 1, characterized in that: S4, preparing copper metal grid lines by electroplating, the thickness of the copper metal grid lines is 5-50 um, and performing a tin protective layer electroplating deposition process on the surface of the copper metal grid lines, the thickness of the deposited tin protective layer is 1-5 um.

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