Silver-coated nickel paste, preparation method thereof, and high-temperature sintering metallization method for crystalline silicon solar cells

A metallization method of crystalline silicon solar cells, characterized in that the method comprises the following steps:

• screen-printing the silver-coated nickel paste on the surface of the crystalline silicon solar cells, drying, and sintering in the air at 500-750° C. to complete the metallization of crystalline silicon solar cells;
• the silver-coated nickel paste is prepared from the following raw materials by weight percentage:
• 80-95% of a conductive powder,
• 1-6% of a glass powder,
• 0.1-3% of an organic resin,
• 0.5-0.8% of a thixotropic agent,
• 0-1% of other auxiliaries, and
• a balance is solvent;
• wherein, the conductive powder is a mixture of silver-coated nickel powder and silver powder at a weight ratio of 1:(0-50);
• the silver-coated nickel powder used has a resistivity of 30-49 μΩ·cm, an oxidation-resistant resistivity of 98-189 μΩ·cm, and a titrated nickel content of ≤0.01 mol/L, wherein the silver content in the silver-coated nickel powder is 25 wt %-50 wt %;
• the silver-coated nickel powder is subjected to surface modification treatment, with the specific steps as follows:
• by adopting a dry modification method, mixing 0.05% to 0.5% of a surface modifier, based on the weight of the silver-coated nickel powder, with the silver-coated nickel powder uniformly to obtain the surface-modified silver-coated nickel powder;
• the glass powder is prepared from mixed raw materials through melting, cooling, and ball milling;
• The mixed raw materials are composed of the following components by weight percentage:
• 35.3%-46.31% of lead oxide (PbO),
• 5.38%-13.2% of silicon dioxide (SiO2),
• 2.64%-4.16% of lithium oxide (Li2O),
• 1.85%-3.5% of zinc oxide (ZnO),
• 1.22%-1.76% of sodium oxide (Na2O),
• 0.43%-2.61% of magnesium oxide (MgO),
• 0.35%-1.57% of calcium oxide (CaO),
• 0-30.53% of tellurium oxide (TeO2),
• 0-21.72% of barium oxide (BaO),
• 0-19.55% of boron oxide (B2O3),
• 0-9.65% of tungsten oxide (WO3), and
• 0-0.53% of copper oxide (CuO),
• the specific preparation steps of the glass powder are as follows:
• weighing raw materials according to the ratio, mixing the raw materials to obtain a mixture;
• melting the mixture at 1,250-1,300° C. for 1.5 h, and then quenching to obtain glass fragments;
• the glass fragments are placed into a 20 L vertical ball mill, into which 15 kg of zirconia spheres with a diameter of 5-10 mm are added, a total of 2 kg of deionized water and oleic acid are added, and the mixture is stirred at a speed of 250 r/min and subjected to ball milling for 8 h to obtain a glass paste;
• The glass paste is then sieved and dried to obtain glass powder with a particle size of 2-5 μm.