Small tower footing alkali polishing additive suitable for high back contact of TOPCon battery and use method of small tower footing alkali polishing additive

Abstract

The invention discloses a small tower footing alkali polishing additive suitable for high back contact of a TOPCon battery and a use method of the small tower footing alkali polishing additive, and relates to the technical field of monocrystalline silicon polishing. Comprising the following components: a corrosion catalyst, a multi-carboxyl polymer, a high-wetting defoaming agent, a surfactant, a chelating agent, a protective agent, hyperbranched polylysine, tannic acid, quinoline yellow, caffeine, 3-(N-morpholinyl)-2-sodium hydroxypropanesulfonate and deionized water. The alkali polishing additive is good in polishing effect under the condition of low weight loss, a relatively rough small-size tower footing can be formed on the back face of a silicon wafer after alkali polishing, and the cell conversion efficiency is gained.

Description

Technical Field

[0001] The invention relates to the technical field of single crystal silicon polishing, and in particular to a small tower base alkaline polishing additive suitable for high back contact of a TOPCon battery and a use method thereof. Background Art

[0002] Solar photovoltaic power generation is an important part of the future energy structure. Among the many solar cell routes, TOPCon cells are considered to be one of the most promising solar high-efficiency cell technologies in the future due to their high power generation efficiency, low cost, low attenuation, simple process flow, good compatibility with existing PERC cell production lines, and easy upgrade. In the preparation process of TOPCon cells, TOPCon alkaline polishing is the mainstream technical route. Compared with acid polishing, it has low cost and high efficiency. However, the alkaline polishing tower base on the back of the substrate is currently large in size, has a high reflectivity, and the efficiency improvement is relatively slow.

[0003] In order to improve the above-mentioned alkali polishing problem, alkali polishing additives are usually added during the alkali polishing process. However, after alkali polishing using the existing alkali polishing additives and the polishing liquid prepared using the alkali polishing additives, the back structure of the single crystal silicon wafer is too flat, which easily leads to insufficient friction between the slurry and the silicon wafer, which is not conducive to the passivation contact of the back oxide layer, and the phenomenon of broken grid occurs during printing, which eventually leads to battery failure. In addition, the alkali polishing additives on the market are used for single crystal silicon alkali polishing, and there are more or less technical defects such as poor stability, poor flatness, and the polishing effect under low weight loss needs to be further improved. The photoelectric conversion efficiency of the battery cell needs to be further improved. The large size of the pyramid base will lead to a decrease in the adhesion of the slurry to the silicon wafer during screen printing, poor contact between the slurry and the silicon wafer, poor appearance, and reduced efficiency.

[0004] In order to overcome the above defects, the Chinese invention patent with the authorization announcement number CN114032035B discloses an additive for alkaline polishing of silicon wafers, the contents of which are: 0.5-2 parts by mass of gelatin, 1-2 parts by mass of acrylamide, 0.5-2 parts by mass of quaternary ammonium salt, 1-3 parts by mass of sodium p-aminosalicylate, 4-5 parts by mass of ammonium thiocyanate, 3-4 parts by mass of alkyl glycoside, 0.1-0.3 parts by mass of sodium benzoate, and 81.7-89.9 parts by mass of water. Adding the additive of the invention to the polishing liquid of alkaline polishing of silicon wafers can change the flatness of the back of the silicon wafer, form a relatively rough small-sized tower base structure on the back of the silicon wafer after alkaline polishing, and slightly reduce the reflectivity of the back of the silicon wafer, which is conducive to the contact of the back slurry, improve the slurry tension, and improve the FF and the electrical performance of the cell. However, the use of the alkaline polishing additive for alkaline polishing of TOPCon cell monocrystalline silicon still has technical defects such as the polishing effect under low weight loss needs to be further improved and the cell efficiency needs to be further improved.

[0005] It can be seen that the development of a small tower base alkaline polishing additive with good polishing effect at low weight loss, which can form a relatively rough small-sized tower base on the back of the silicon wafer after alkaline polishing, and a high back contact small tower base suitable for TOPCon batteries that has a gain in battery conversion efficiency and a method of using the additive meet market demand, have broad market value and application prospects, and are of great significance to promoting the further development of the TOPCon battery field. Summary of the invention

[0006] The main purpose of the present invention is to provide a small tower base alkali polishing additive with good polishing effect at low weight loss, which can form a relatively rough small-sized tower base on the back of the silicon wafer after alkali polishing, and is suitable for TOPCon battery with high back contact and a method of using the small tower base alkali polishing additive which has a gain in battery conversion efficiency.

[0007] To achieve the above purpose, the present invention provides a small tower base alkaline polishing additive suitable for high back contact of TOPCon battery, including the following components calculated by mass percentage: 0.2wt%-0.4wt% of corrosion catalyst, 0.08wt%-0.15wt% of polycarboxyl polymer, 0.5wt%-0.8wt% of high wetting defoaming agent, 0.5wt%-1.5wt% of surfactant, 0.1wt%-0.3wt% of chelating agent, 0.03wt%-0.1wt% of protective agent, 0.03wt%-0.06wt% of hyperbranched polylysine, 0.01wt%-0.1wt% of tannic acid, 0.03wt%-0.08wt% of quinoline yellow, 0.01wt%-0.04wt% of caffeine, 0.1wt%-0.25wt% of 3-(N-morpholinyl)-2-hydroxypropanesulfonate sodium, and the balance is deionized water.

[0008] Preferably, the corrosion catalyst is one or a combination of two or more of sodium persulfate, m-chloroperbenzoic acid, and potassium peroxymonosulfonate.

[0009] Preferably, the polycarboxyl polymer is one or a combination of two or more of polyacrylic acid and polyglycolic acid.

[0010] Preferably, the number average molecular weight of the polycarboxyl polymer is 15,000.

[0011] Preferably, the high wetting and degassing agent is one or a combination of two or more of glycerol, dextran and water-soluble starch.

[0012] Preferably, the surfactant is one or a combination of two or more of Span 80, Tween 20, sodium dodecylbenzene sulfonate, and lauroylamidopropyl betaine.

[0013] Preferably, the chelating agent is one or a combination of two or more of succinic acid, malic acid, EDTA and sodium gluconate.

[0014] Preferably, the protective agent is one or a combination of two or more of calcium chloride, calcium acetate and calcium phosphate.

[0015] Preferably, there is no special requirement for the source of the hyperbranched polylysine. In one embodiment of the present invention, the hyperbranched polylysine is prepared according to the method of Example 1 of the Chinese invention patent application publication number CN117205361A.

[0016] Another object of the present invention is to provide a method for using the small tower base alkali polishing additive for high back contact of TOPCon battery, comprising the following steps: Step S1, uniformly mixing the components of the small tower-based alkali polishing additive with high back contact suitable for TOPCon batteries to obtain the small tower-based alkali polishing additive with high back contact suitable for TOPCon batteries; Step S2, adding the small tower base alkaline polishing additive for high back contact of TOPCon battery prepared in step S1 into the alkaline solution and stirring well to obtain a polishing solution; Step S3, polishing the single crystal silicon using the polishing liquid prepared in step S2.

[0017] Preferably, the mass content of the low-weight-loss single-crystal silicon alkali polishing additive suitable for TOPCon thinning in the polishing liquid in step S2 is 0.5% to 2.5%.

[0018] Preferably, the alkali solution in step S2 is a sodium hydroxide solution or a potassium hydroxide solution; the mass percentage concentration of the alkali solution is 1.5% to 2%.

[0019] Preferably, the polishing process in step S3 is performed at a temperature of 60 to 65° C. and for a time of 170 to 240 seconds.

[0020] Due to the application of the above technical solution, the present invention has the following beneficial effects: (1) The method for using the small tower base alkaline polishing additive for high back contact of TOPCon battery disclosed in the present invention has simple process operation, easy implementation, low dependence on equipment, no pollution in the alkaline polishing process, controllable tower base structure size, and is suitable for large-scale production.

[0021] (2) The small tower base alkaline polishing additive for high back contact of TOPCon battery disclosed in the present invention comprises the following components calculated by mass percentage: 0.2wt%-0.4wt% of corrosion catalyst, 0.08wt%-0.15wt% of polycarboxyl polymer, 0.5wt%-0.8wt% of high wetting degassing agent, 0.5wt%-1.5wt% of surfactant, 0.1wt%-0.3wt% of chelating agent, 0.03wt%-0.1wt% of protective agent, 0.03wt%-0.0 6wt% of hyperbranched polylysine, 0.01wt%-0.1wt% of tannic acid, 0.03wt%-0.08wt% of quinoline yellow, 0.01wt%-0.04wt% of caffeine, 0.1wt%-0.25wt% of 3-(N-morpholinyl)-2-hydroxypropanesulfonate sodium, and the balance is deionized water; through the mutual cooperation between the components, the prepared alkali polishing additive has good polishing effect under low weight loss, can form a relatively rough small-sized tower base on the back of the silicon wafer after alkali polishing, and has a benefit on the battery conversion efficiency.

[0022] (3) The alkaline polishing additive for small tower base with high back contact suitable for TOPCon battery disclosed in the present invention slows down the expansion speed of the tower base and increases the longitudinal corrosion of the tower base during the alkaline polishing process of TOPCon battery through the reasonable selection of component formula and the combined effect of multiple components, thereby increasing the contact area of ​​the back side and achieving better contact with the slurry, thereby improving the back side contact and filling factor; at the same time, it can also improve the polishing effect under low weight loss; the compatibility between the various components is good, so that the manufactured product has not only good stability and significant polishing effect, but also better repeatability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a Zeta microscope image of a single crystal silicon polished surface alkali-polished using the alkali-polishing additive of Example 1; Figure 2 This is a side SEM image of single crystal silicon that was alkali-polished using the alkali-polishing additive of Example 1; Figure 3 This is a SEM image of the front side of single crystal silicon that was alkali-polished using the alkali-polishing additive of Example 1. DETAILED DESCRIPTION

[0024] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0025] Example 1, a small tower base alkaline polishing additive suitable for high back contact of TOPCon battery, including the following components calculated by mass percentage: 0.2wt% of corrosion catalyst, 0.08wt% of polycarboxyl polymer, 0.5wt% of high wetting defoaming agent, 0.5wt% of surfactant, 0.1wt% of chelating agent, 0.03wt% of protective agent, 0.03wt% of hyperbranched polylysine, 0.01wt% of tannic acid, 0.03wt% of quinoline yellow, 0.01wt% of caffeine, 0.1wt% of 3-(N-morpholinyl)-2-hydroxypropanesulfonate sodium, and the balance is deionized water.

[0026] The corrosion catalyst is sodium persulfate; the polycarboxyl polymer is polyacrylic acid; the number average molecular weight of the polycarboxyl polymer is 15000; the high wetting defoaming agent is glycerol; the surfactant is Span 80; the chelating agent is succinic acid; the protective agent is calcium chloride; the hyperbranched polylysine is prepared according to the method of Example 1 of the Chinese invention patent with application publication number CN117205361A.

[0027] A method for using the small tower base alkaline polishing additive suitable for high back contact of TOPCon battery comprises the following steps: Step S1, uniformly mixing the components of the small tower-based alkali polishing additive with high back contact suitable for TOPCon batteries to obtain the small tower-based alkali polishing additive with high back contact suitable for TOPCon batteries; Step S2, adding the small tower base alkaline polishing additive for high back contact of TOPCon battery prepared in step S1 into the alkaline solution and stirring well to obtain a polishing solution; Step S3, polishing the single crystal silicon using the polishing liquid prepared in step S2.

[0028] The mass content of the low-weight-loss single-crystal silicon alkali polishing additive suitable for TOPCon thinning in the polishing liquid in step S2 is 0.5%; the alkali solution in step S2 is sodium hydroxide solution; the mass percentage concentration of the alkali solution is 1.5%; the temperature of the polishing treatment in step S3 is 60°C and the time is 170s.

[0029] Example 2, a small tower base alkaline polishing additive suitable for high back contact of TOPCon battery, including the following components calculated by mass percentage: 0.25wt% of corrosion catalyst, 0.1wt% of polycarboxyl polymer, 0.6wt% of high wetting defoaming agent, 0.7wt% of surfactant, 0.15wt% of chelating agent, 0.05wt% of protective agent, 0.04wt% of hyperbranched polylysine, 0.03wt% of tannic acid, 0.05wt% of quinoline yellow, 0.02wt% of caffeine, 0.15wt% of 3-(N-morpholinyl)-2-hydroxypropanesulfonate sodium, and the balance is deionized water.

[0030] The corrosion catalyst is m-chloroperbenzoic acid; the polycarboxyl polymer is polyglycolic acid; the number average molecular weight of the polycarboxyl polymer is 15000; the high wetting defoaming agent is dextran; the surfactant is Tween 20; the chelating agent is malic acid; the protective agent is calcium acetate; the hyperbranched polylysine is prepared according to the method of Example 1 of the Chinese invention patent with application publication number CN117205361A.

[0031] A method for using the small tower base alkaline polishing additive suitable for high back contact of TOPCon battery comprises the following steps: Step S1, uniformly mixing the components of the small tower-based alkali polishing additive with high back contact suitable for TOPCon batteries to obtain the small tower-based alkali polishing additive with high back contact suitable for TOPCon batteries; Step S2, adding the small tower base alkaline polishing additive for high back contact of TOPCon battery prepared in step S1 into the alkaline solution and stirring well to obtain a polishing solution; Step S3, polishing the single crystal silicon using the polishing liquid prepared in step S2.

[0032] The mass content of the low-weight-loss single-crystal silicon alkali polishing additive suitable for TOPCon thinning in the polishing liquid in step S2 is 1.5%; the alkali solution in step S2 is potassium hydroxide solution; the mass percentage concentration of the alkali solution is 1.7%; the temperature of the polishing treatment in step S3 is 62°C and the time is 190s.

[0033] Example 3, a small tower base alkaline polishing additive suitable for high back contact of TOPCon battery, including the following components calculated by mass percentage: 0.3wt% of corrosion catalyst, 0.12wt% of polycarboxyl polymer, 0.65wt% of high wetting defoaming agent, 1wt% of surfactant, 0.2wt% of chelating agent, 0.06wt% of protective agent, 0.045wt% of hyperbranched polylysine, 0.06wt% of tannic acid, 0.06wt% of quinoline yellow, 0.025t% of caffeine, 0.18wt% of 3-(N-morpholinyl)-2-hydroxypropanesulfonate sodium, and the balance is deionized water.

[0034] The corrosion catalyst is potassium peroxymonosulfonate; the polycarboxyl polymer is polyacrylic acid; the number average molecular weight of the polycarboxyl polymer is 15000; the high wetting defoaming agent is water-soluble starch; the surfactant is sodium dodecylbenzene sulfonate; the chelating agent is EDTA; the protective agent is calcium phosphate; the hyperbranched polylysine is prepared according to the method of Example 1 of the Chinese invention patent with application publication number CN117205361A.

[0035] A method for using the small tower base alkaline polishing additive suitable for high back contact of TOPCon battery comprises the following steps: Step S1, uniformly mixing the components of the small tower-based alkali polishing additive with high back contact suitable for TOPCon batteries to obtain the small tower-based alkali polishing additive with high back contact suitable for TOPCon batteries; Step S2, adding the small tower base alkaline polishing additive for high back contact of TOPCon battery prepared in step S1 into the alkaline solution and stirring well to obtain a polishing solution; Step S3, polishing the single crystal silicon using the polishing liquid prepared in step S2.

[0036] The mass content of the low-weight-loss single-crystal silicon alkali polishing additive suitable for TOPCon thinning in the polishing liquid in step S2 is 1.5%; the alkali solution in step S2 is sodium hydroxide solution; the mass percentage concentration of the alkali solution is 1.8%; the temperature of the polishing treatment in step S3 is 63°C and the time is 210s.

[0037] Example 4, a small tower base alkaline polishing additive suitable for high back contact of TOPCon battery, including the following components calculated by mass percentage: 0.35wt% of corrosion catalyst, 0.13wt% of polycarboxyl polymer, 0.75wt% of high wetting defoaming agent, 1.4wt% of surfactant, 0.25wt% of chelating agent, 0.08wt% of protective agent, 0.055wt% of hyperbranched polylysine, 0.08wt% of tannic acid, 0.07wt% of quinoline yellow, 0.035wt% of caffeine, 0.23wt% of 3-(N-morpholinyl)-2-hydroxypropanesulfonate sodium, and the balance is deionized water.

[0038] The corrosion catalyst is a mixture of sodium persulfate, meta-chloroperbenzoic acid, and potassium peroxymonosulfonate in a mass ratio of 1:1:2; the polycarboxyl polymer is a mixture of polyacrylic acid and polyglycolic acid in a mass ratio of 3:5; the number average molecular weight of the polycarboxyl polymer is 15000; the high wetting defoaming agent is a mixture of glycerol, dextran, and water-soluble in a mass ratio of 1:2:3; the surfactant is a mixture of Span 80, Tween 20, sodium dodecylbenzene sulfonate, and lauroylamidopropyl betaine in a mass ratio of 1:1:1:3; the chelating agent is a mixture of succinic acid, malic acid, EDTA, and sodium gluconate in a mass ratio of 1:3:2:1; the protective agent is a mixture of calcium chloride, calcium acetate, and calcium phosphate in a mass ratio of 1:3:5; the hyperbranched polylysine is prepared according to the method of Example 1 of the Chinese invention patent with application publication number CN117205361A.

[0039] A method for using the small tower base alkaline polishing additive suitable for high back contact of TOPCon battery comprises the following steps: Step S1, uniformly mixing the components of the small tower-based alkali polishing additive with high back contact suitable for TOPCon batteries to obtain the small tower-based alkali polishing additive with high back contact suitable for TOPCon batteries; Step S2, adding the small tower base alkaline polishing additive for high back contact of TOPCon battery prepared in step S1 into the alkaline solution and stirring well to obtain a polishing solution; Step S3, polishing the single crystal silicon using the polishing liquid prepared in step S2.

[0040] The mass content of the low-weight-loss single-crystal silicon alkali polishing additive suitable for TOPCon thinning in the polishing liquid in step S2 is 2.3%; the alkali solution in step S2 is a potassium hydroxide solution; the mass percentage concentration of the alkali solution is 1.9%; the temperature of the polishing treatment in step S3 is 64°C and the time is 230s.

[0041] Example 5, a small tower base alkaline polishing additive suitable for high back contact of TOPCon battery, including the following components calculated by mass percentage: 0.4wt% of corrosion catalyst, 0.15wt% of polycarboxyl polymer, 0.8wt% of high wetting defoaming agent, 1.5wt% of surfactant, 0.3wt% of chelating agent, 0.1wt% of protective agent, 0.06wt% of hyperbranched polylysine, 0.1wt% of tannic acid, 0.08wt% of quinoline yellow, 0.04wt% of caffeine, 0.25wt% of 3-(N-morpholinyl)-2-hydroxypropanesulfonate sodium, and the balance is deionized water.

[0042] The corrosion catalyst is sodium persulfate; the polycarboxyl polymer is polyacrylic acid; the number average molecular weight of the polycarboxyl polymer is 15000; the high wetting defoaming agent is dextran; the surfactant is lauroamidopropyl betaine; the chelating agent is sodium gluconate; the protective agent is calcium acetate; the hyperbranched polylysine is prepared according to the method of Example 1 of the Chinese invention patent with application publication number CN117205361A.

[0043] A method for using the small tower base alkaline polishing additive suitable for high back contact of TOPCon battery comprises the following steps: Step S1, uniformly mixing the components of the small tower-based alkali polishing additive with high back contact suitable for TOPCon batteries to obtain the small tower-based alkali polishing additive with high back contact suitable for TOPCon batteries; Step S2, adding the small tower base alkaline polishing additive for high back contact of TOPCon battery prepared in step S1 into the alkaline solution and stirring well to obtain a polishing solution; Step S3, polishing the single crystal silicon using the polishing liquid prepared in step S2.

[0044] The mass content of the low-weight-loss single-crystal silicon alkali polishing additive suitable for TOPCon thinning in the polishing liquid in step S2 is 2.5%; the alkali solution in step S2 is sodium hydroxide solution; the mass percentage concentration of the alkali solution is 2%; the temperature of the polishing treatment in step S3 is 65°C and the time is 240s.

[0045] Comparative Example 1 The present invention provides a small tower-based alkali polishing additive suitable for high back contact of TOPCon batteries and a method of using the same, which is similar to Example 1, except that hyperbranched polylysine and tannic acid are not added.

[0046] Comparative Example 2 The present invention provides a small tower-based alkaline polishing additive suitable for high back contact of TOPCon batteries and a method of using the same, which is similar to Example 1, except that caffeine and sodium 3-(N-morpholinyl)-2-hydroxypropanesulfonate are not added.

[0047] The above Examples 1-5 and Comparative Examples 1-2 involved small tower-based alkaline polishing additives suitable for high back contact of TOPCon batteries were subjected to relevant performance tests. The test results are shown in Table 1. The test method is as follows: a reflectivity test system is used to measure the integrated reflectivity in the wavelength range of 300-1100nm; the weight loss is counted and calculated; the single crystal silicon after alkali polishing in each example is put into the subsequent solar cell preparation process to be made into finished battery cells, and the efficiency of the finished battery cells is tested. Except for the above-mentioned alkali polishing additives and their use methods, the production of each battery cell is different, and other processes and raw materials are consistent.

[0048] Table 1

[0049] As can be seen from Table 1, the small tower-based alkaline polishing additive for high back contact of TOPCon batteries disclosed in the embodiment of the present invention has a more excellent polishing effect at low weight loss than the comparative product, has a gain in battery conversion efficiency, and has a suitable reflectivity; the addition of hyperbranched polylysine, tannic acid, caffeine and sodium 3-(N-morpholinyl)-2-hydroxypropanesulfonate is beneficial to improving the above properties.

[0050] pass Figure 1-Figure 3 It can be seen that the back side of the single crystal silicon wafer alkaline polished with the small tower base alkaline polishing additive for high back contact of TOPCon battery manufactured by Example 1 of the present invention forms a relatively rough small-sized tower base.

[0051] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A small tower base alkaline polishing additive suitable for high back contact of TOPCon battery, characterized in that: Includes the following components calculated by mass percentage: 0.2wt%-0.4wt% of corrosion catalyst, 0.08wt%-0.15wt% of polycarboxyl polymer, 0.5wt%-0.8wt% of high wetting defoaming agent, 0.5wt%-1.5wt% of surfactant, 0.1wt%-0.3wt% of chelating agent, 0.03wt%-0.1wt% of protective agent, 0.03wt%-0.06wt% of hyperbranched polylysine, 0.01wt%-0.1wt% of tannic acid, 0.03wt%-0.08wt% of quinoline yellow, 0.01wt%-0.04wt% of caffeine, 0.1wt%-0.25wt% of sodium 3-(N-morpholinyl)-2-hydroxypropanesulfonate, and the balance is deionized water.

2. The small tower base alkaline polishing additive for high back contact of TOPCon battery according to claim 1, characterized in that: The corrosion catalyst is one or a combination of two or more of sodium persulfate, m-chloroperbenzoic acid, and potassium peroxymonosulfonate.

3. The small tower base alkaline polishing additive for high back contact of TOPCon battery according to claim 1, characterized in that: The polycarboxyl polymer is one or a combination of two or more of polyacrylic acid and polyglycolic acid; the number average molecular weight of the polycarboxyl polymer is 15,000.

4. The small tower base alkaline polishing additive for high back contact of TOPCon battery according to claim 1, characterized in that: The high wetting and defoaming agent is one or a combination of two or more of glycerol, dextran, and water-soluble starch; the surfactant is one or a combination of two or more of Span 80, Tween 20, sodium dodecylbenzene sulfonate, and lauroylamidopropyl betaine.

5. The small tower base alkaline polishing additive for high back contact of TOPCon battery according to claim 1, characterized in that: The chelating agent is one or a combination of two or more of succinic acid, malic acid, EDTA and sodium gluconate.

6. The small tower base alkaline polishing additive for high back contact of TOPCon battery according to claim 1, characterized in that: The protective agent is one or a combination of two or more of calcium chloride, calcium acetate and calcium phosphate.

7. A method for using the small tower base alkaline polishing additive for high back contact of TOPCon battery according to any one of claims 1 to 6, characterized in that: The steps include: Step S1, uniformly mixing the components of the small tower-based alkali polishing additive with high back contact suitable for TOPCon batteries to obtain the small tower-based alkali polishing additive with high back contact suitable for TOPCon batteries; Step S2, adding the small tower base alkaline polishing additive for high back contact of TOPCon battery prepared in step S1 into the alkaline solution and stirring well to obtain a polishing solution; Step S3, polishing the single crystal silicon using the polishing liquid prepared in step S2.

8. The method for using the small tower base alkaline polishing additive for high back contact of TOPCon battery according to claim 7, characterized in that: The mass content of the low-weight-loss single-crystal silicon alkali polishing additive suitable for TOPCon thinning in the polishing liquid in step S2 is 0.5% to 2.5%.

9. The method for using the small tower base alkaline polishing additive for high back contact of TOPCon battery according to claim 7, characterized in that: The alkali solution in step S2 is a sodium hydroxide solution or a potassium hydroxide solution; the mass percentage concentration of the alkali solution is 1.5% to 2%.

10. The method for using the small tower base alkaline polishing additive for high back contact of TOPCon battery according to claim 7, characterized in that: The polishing process in step S3 is performed at a temperature of 60 to 65° C. and for a time of 170 to 240 seconds.

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