WO2015003292A1

WO2015003292A1 - Composite electrode material and process for preparing front electrode of photovoltaic cell

Info

Publication number: WO2015003292A1
Application number: PCT/CN2013/001010
Authority: WO
Inventors: 余小翠
Original assignee: Yu Xiaocui
Priority date: 2013-07-08
Filing date: 2013-08-26
Publication date: 2015-01-15

Abstract

Provided are a composite electrode material (4) and process for preparing the front electrode of a photovoltaic cell. The composite material comprises a conductive core (7) disposed inside the composite electrode material, and a connecting layer (8) disposed on the surface of the conductive core. The preparation process comprises: preparing conductive paste; coating the surface of a conductive metal wire with the conductive paste, and drying and solidifying the conductive metal wire coated with the conductive paste to form the composite electrode material; heating a cell plate (2) or the composite electrode material to partially or completely melt the organic adhesive in the composite electrode material to restore viscidity of the composite electrode material, such that the composite electrode material is bonded to the front surface of the cell plate according to a designed pattern; employing spray coating to spray the conductive paste on the front of the cell plate to prepare a main gate line (3); putting the cell plate into a drying stove and a sintering furnace for drying at 200°C-500°C and sintering at 500°C-900°C respectively to form a front electrode. The contact function and conductive function of an electrode are separated to improve the conductivity of the electrode. The front electrode of a photovoltaic cell plate has less shielding and high conductivity.

Description

Composite electrode material and process for preparing front electrode of photovoltaic cell

The invention belongs to the technical field of photovoltaic cells, and in particular relates to a composite electrode material and a process for preparing a front electrode of a photovoltaic cell. Background technique

The front metallization of photovoltaic cells is mainly achieved by screen printing conductive paste. The prepared electrode has a small aspect ratio, large electrode width, uneven width and severe edge collapse, and the electrode height is small and the height is not uniform. For photovoltaic cells, large electrode width and severe collapse mean that the front side has a large light-shielding area, and the low electrode height and unevenness means that the electrode has poor conductivity and large internal resistance, which seriously affects and restricts the efficiency of the photovoltaic cell.

The front electrode of the photovoltaic cell mainly has two functions: On the one hand, the lower part of the electrode forms an alloy and ohmic contact with the front surface of the battery, and functions as an electrical connection; on the other hand, the electrode body conducts current and acts as a conductor. For the role of electrical connection, the current silver paste can play a better effect, achieving a lower contact resistance, but for the role of the conductor, since the silver paste itself is composed of silver powder, the electrode prepared therefrom is a porous The structure has much lower conductivity than the dense conductor of pure metal, which also limits the improvement of the conductivity of the electrode, thereby restricting the efficiency of the photovoltaic cell. At present, the conductive paste used for the front metallization of photovoltaic cells is mainly silver paste. Due to the requirement of conductivity, the content of silver in silver paste is very high, reaching about 90%, silver is a precious metal, and the current electrode materials for photovoltaic cells are also selected. It has seriously restricted the further decline in the manufacturing cost of photovoltaic cells.

In addition, the traditional process of realizing the metallization of the front side of the photovoltaic cell by screen printing and silver paste is to use the permeability of the mesh version to squeeze the high viscosity silver paste through the mesh under a certain pressure. To the front of the photovoltaic cell, due to the high viscosity of the slurry and the small opening of the screen, it requires a lot of pressure to form the electrode pattern that meets the standard. Such a large pressure increases the fragmentation rate when printing the battery. Under the trend that the battery will become thinner and thinner, the traditional screen printing metallization scheme hinders the application of new technologies. Summary of the invention

The object of the present invention is to provide a composite electrode material and a process for preparing a front electrode of a photovoltaic cell with high cost and low efficiency of the photovoltaic cell, which has the advantages of low cost and high efficiency of the photovoltaic cell. , not only can improve the efficiency of cell conversion, but also reduce production costs.

The embodiment of the invention is realized by the composite electrode material for preparing the front electrode of the photovoltaic cell, and the composite electrode material for preparing the front electrode of the photovoltaic cell comprises:

A conductive core disposed inside the composite electrode material and a connection layer disposed on the surface of the conductive core, the connection layer being formed by drying and curing the conductive paste coated on the surface of the conductive core.

Further, the conductive core is selected from the group consisting of gold wire, silver wire, copper wire, aluminum wire, silicon aluminum wire, and conductive fiber of polymer fiber or carbon fiber, and the conductive core has a diameter of 5 μm to 50 μm.

Further, the thickness of the connecting layer is 3 micrometers to 20 micrometers, and the conductive paste is selected from the group consisting of silver paste, copper paste, nickel paste, a paste made of metal powder, and the curing temperature is 50 ° C - 200 ° C, conductive Pastes include metal powders, metal or non-metal oxides, organic solvents, organic binders, and additives.

Further, the composition and weight percentage of the conductive paste include: metal powder 70-90%; metal or non-metal oxide 1-10%; organic binder 1-10%; organic solvent 1-10%; additive 1 -5%.

Further, when the composite electrode material is used for the front electrode, the temperature reaches 100 ° C - 500 ° C, the connection layer after drying and curing has viscosity, and the composite electrode material is used for preparing the front electrode of the photovoltaic cell.

Further, the metal powder has a particle size of 0.1-2 μm, a spherical or quasi-spherical shape, and the metal or non-metal oxide is lead, bismuth, calcium, magnesium, zinc, platinum, rhodium, ruthenium, nickel, chromium, palladium, boron, One or a mixture of phosphorus oxides;

The organic binder is selected from the group consisting of ethyl cellulose, acrylic resin, nitrocellulose, phenol resin, and mixtures thereof;

The organic solvent is selected from the group consisting of terpineol, carbitol, diethylene glycol acetate, and mixtures thereof;

Additives include surfactants, thixotropic agents, defoamers, dispersants, sintering inhibitors, oxidation inhibitors Formulations and swelling inhibitors.

Another object of the present invention is to provide a process for preparing a front electrode of a photovoltaic cell using the above composite electrode material. The process for preparing the front electrode of the photovoltaic cell comprises the following steps:

Step one, preparing a conductive paste: mixing metal powder, metal or non-metal oxide, organic binder, organic solvent and additive to obtain a conductive paste; in the conductive paste, the mass percentage of the metal powder is 70-90%, the metal or non-metal oxide content is 1-10% by mass, the organic binder is 1-10% by mass, and the organic solvent is 1-10% by mass. The mass percentage of the additive is 1-5%;

Step 2, preparing a composite electrode material: the conductive paste is uniformly coated on the surface of the conductive wire, and is cured by drying;

Step 3: heating the battery sheet or the composite electrode material to melt the organic binder in the composite electrode material partially or completely, restore the viscosity, and firmly bond the composite electrode material to the front surface of the battery sheet according to the design pattern. Bonding treatment;

Step 4, preparing a main grid line on the front side of the battery sheet: spraying the conductive paste body on the surface of the battery sheet to form a main grid line;

Step 5: The battery piece is placed in a reheating furnace and a sintering furnace, dried at 200 ° C - 500 ° C, and sintered at 500 ° C - 900 ° C to form a front electrode.

Further, the two ends of the composite electrode material disposed on the front surface of the battery sheet are 0.5-1.5 mm apart from the front edge of the battery sheet, the ends of the main grid line are 0.5-1.5 mm from the edge of the battery sheet, and the number of main grid lines is 1-10. .

Further, in the first step, the metal powder has a particle size ranging from 0.1 to 2 μm, and the shape is spherical or quasi-spherical; in the third step, the heating of the composite electrode material or the cell sheet can be achieved by means of thermosonic, infrared or laser. It is preferably infrared heating, and the heating temperature is from 80 ° C to 500 ° C. Further, in the second step, the diameter of the conductive wire is 5 micrometers to 50 micrometers, the thickness of the conductive paste after drying and curing is 3 micrometers to 20 micrometers, and the drying and curing temperature of the conductive paste is 50 ° C - 200 ° C.

Composite electrode material and process for preparing front electrode of photovoltaic cell provided by the invention The conductive core of the electrode material is disposed as a wire or a conductive fiber, and the wire or the conductive fiber used serves to conduct a current, and the conductivity is greatly improved compared to the electrode prepared by the silver paste, thereby improving the conductive effect; the composite electrode of the present invention The connecting layer of the material is uniformly coated on the surface of the conductive core by a conductive paste made of metal powder, and has a certain viscosity at a certain temperature, so that the electrode material itself can be firmly attached to the surface of the substrate, thereby avoiding the existence in the subsequent use. The problem of the warpage improves the adhesion and adhesion; the conductive paste of the present invention is uniformly coated on the surface of the conductive core and then dried and solidified. When the electrode is fabricated, the amount of silver can be greatly reduced, and the P strip has a low solar energy. The electrode manufacturing cost of the battery sheet; when the composite electrode material of the invention is used for preparing the front electrode of the solar cell sheet, the width of the fine grid line on the front side of the solar cell is reduced, and a fine grid line having a width of 20-50 micrometers is prepared, and the height can be Up to 15-40 microns, the electrode aspect ratio is large; the conductivity of the fine grid line can be increased by 20% compared to the conventional silver paste grid line The above, the electrode resistance is small, the internal resistance of the battery is small, and the conversion efficiency of the photovoltaic cell is improved. DRAWINGS

1 is a schematic view showing a cross section of a composite electrode material according to an embodiment of the present invention;

2 is a schematic structural view of a composite electrode material according to an embodiment of the present invention;

3 is a front structural view of a photovoltaic cell in which a main gate line is prepared according to an embodiment of the present invention; FIG. 4 is a front structural view of a photovoltaic cell according to an embodiment of the present invention; A cross-sectional view of the junction of the cell sheet and the composite electrode in which the bonding treatment is completed;

6 is a schematic cross-sectional view of a junction between a battery chip and a composite electrode for completing the preparation of the front electrode according to an embodiment of the present invention;

7 is a flow chart showing a process of preparing a front electrode of a photovoltaic cell according to an embodiment of the present invention.

In the figure: 1, conductive wire; 2, battery; 3, main grid line; 4, composite electrode material; 5, bonding interface; 6, bonding interface; 7, conductive core; 8, connecting layer. detailed description In order to make the objects, technical solutions and advantages of the present invention more comprehensible, the present invention will be further described in detail below with reference to the embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows the composite electrode material structure for the preparation of front side electrodes of photovoltaic cells provided by the present invention. For the convenience of description, only the parts related to the present invention are shown.

The composite electrode material for preparing the front electrode of the photovoltaic cell according to the embodiment of the invention, the composite electrode material for preparing the front electrode of the photovoltaic cell comprises:

As an optimization scheme of the embodiment of the present invention, the conductive core is selected from the group consisting of gold wire, silver wire, copper wire, aluminum wire, silicon aluminum wire, and conductive fiber of polymer fiber or carbon fiber, and the diameter of the conductive core is 5 micrometers. 50 microns.

As an optimization scheme of the embodiment of the present invention, the thickness of the connecting layer is 3 micrometers to 20 micrometers, and the conductive paste is selected from the group consisting of silver paste, copper paste, nickel paste, paste made of metal powder, and the curing temperature is 50. °C-200 ° C, conductive paste includes metal powder, metal or non-metal oxides, organic solvents, organic binders and additives.

As an optimization scheme of the embodiment of the present invention, the composition and the weight percentage content of the conductive paste include: metal powder 70-90%; metal or non-metal oxide 1-10%; organic binder 1-10%; organic Solvent 1-10%; Additive 1-5%.

As an optimization scheme of the embodiment of the present invention, when the composite electrode material is used for the front electrode, the temperature reaches 100° C.-500° C., the connection layer after drying and curing has viscosity, and the composite electrode material is used for preparing the front surface of the photovoltaic cell. electrode.

As an optimization scheme of the embodiment of the present invention, the metal powder has a particle size of 0.1-2 μη, the shape is spherical or quasi-spherical, and the metal or non-metal oxide is lead, antimony, calcium, magnesium, zinc, platinum, rhodium, ruthenium, a mixture of one or more of nickel, chromium, palladium, boron, and phosphorus oxide;

The organic binder is selected from the group consisting of ethyl cellulose, acrylic resin, nitrocellulose, phenolic resin and their mixture;

Additives include surfactants, thixotropic agents, antifoaming agents, dispersing agents, sintering inhibitors, oxidation inhibitors, and swelling inhibitors.

The application principle of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

The specific implementation of the composite electrode material of the front electrode of the photovoltaic cell is further described in conjunction with FIG. 1 :

Example 1

The composite electrode material of the present invention is composed of a conductive core 7 at the core of the electrode material and a connecting layer 8 at the surface layer of the conductive core 7, and the connecting layer 8 is cured by drying of the conductive silver paste uniformly coated on the surface of the conductive core 7. The drying curing temperature is 50°C-200°C, the conductive core 7 is 10-20 micron copper wire, and the conductive silver paste is 5% by weight of the conductive silver paste, metal or non-metal oxide. The organic binder accounts for 5%, the organic solvent accounts for 5%, the additive accounts for 1%, and the rest is silver powder. The silver powder has a particle size range of 0.1 -2 μ πι, the shape is spherical or quasi-spherical, and the thickness of the connecting layer 8 is 5-10 micron, metal or non-metal oxide is a mixture of one or more of lead, bismuth, calcium, magnesium, zinc, platinum, rhodium, ruthenium, nickel, chromium, palladium, boron, phosphorus, etc. The organic binder is ethyl cellulose, the organic solvent is diethylene glycol diethyl ether, and the additives include surfactants, thixotropic agents, antifoaming agents, dispersing agents, sintering inhibitors, oxidation inhibitors, swelling inhibitors, and composites. Electrode material is used to make the front When the electrode temperature reaches 100 ° C -500 ° C, after drying the cured connecting layer 8 having a viscosity at this time;

Example 2:

The composite electrode material of the present invention is composed of a conductive core 7 at the core of the electrode material and a connecting layer 8 at the surface layer of the conductive core 7. The connecting layer 8 is cured by a conductive silver paste uniformly coated on the surface of the conductive core. The drying and curing temperature is 50°C-200°C, the conductive core 7 is 10-20 micrometers of silver wire, and the conductive silver paste is 8% by weight of the conductive silver paste, metal or non-metal oxide. The organic binder accounts for 5%, the organic solvent accounts for 5%, the additive accounts for 2%, and the rest is silver powder. The silver powder has a particle size ranging from 0.1 to 2 μm, the shape is spherical or quasi-spherical, and the thickness of the connecting layer 8 is 5-10 microns, metal or The non-metal oxide is a mixture of one or more of lead, bismuth, calcium, magnesium, rhodium, platinum, rhodium, ruthenium, nickel, chromium, palladium, boron, phosphorus, etc., and the organic binder is B. Cellulose, organic solvent is diethylene glycol ether, additives include surfactants, thixotropic agents, defoamers, dispersants, sintering inhibitors, oxidation inhibitors, expansion inhibitors, composite electrode materials used in the production of positive When the electrode is at a temperature of 100 ° C to 500 ° C, the connection layer 8 after drying and curing is sticky at this time;

Example 3:

The composite electrode material of the present invention is composed of a conductive core 7 at the core of the electrode material and a connecting layer 8 at the surface layer of the conductive core 7, and the connecting layer 8 is cured by drying of the conductive silver paste uniformly coated on the surface of the conductive core 7. The drying curing temperature is 50°C-200°C, the conductive core 7 is 10-20 micrometer aluminum wire, and the conductive silver paste is 10% by weight of the conductive silver paste, metal or non-metal oxide. The organic binder accounts for 1%, the organic solvent accounts for 1%, the additive accounts for 1%, and the rest is silver powder. The silver powder has a particle size ranging from 0.1 to 2 μm, the shape is spherical or quasi-spherical, and the thickness of the connecting layer 8 is 5-10 micron, metal or non-metal oxide is a mixture of one or more of lead, bismuth, calcium, magnesium, rhodium, platinum, rhodium, ruthenium, nickel, chromium, palladium, boron, phosphorus, etc. The organic binder is ethyl cellulose, the organic solvent is diethylene glycol diethyl ether, and the additives include surfactants, thixotropic agents, antifoaming agents, dispersing agents, sintering inhibitors, oxidation inhibitors, swelling inhibitors, and composites. Electrode material is used in the production At the front electrode, the temperature reaches 100. C-500 ° C, the connection layer after drying and curing 8 is sticky at this time;

Example 4:

The composite electrode material of the present invention is composed of a conductive core 7 at the core of the electrode material and a connecting layer 8 at the surface layer of the conductive core 7. The connecting layer 8 is cured by a conductive paste uniformly coated on the surface of the conductive core 7. The conductive paste is a conductive nickel-silver mixed paste, the drying and curing temperature is 50° C.-200° C., the conductive core 7 is a 10-20 micron copper wire, and the conductive silver paste is in the weight percentage of the conductive paste. Metal or non-metal oxides accounted for 8%, organic binders accounted for 3%, organic solvents accounted for 3%, additives accounted for 3%, and the balance was a mixture of silver powder and nickel powder. The weight ratio of silver powder to nickel powder was 7: 1, silver powder and nickel powder particle size range of 0.1-2 μ ηι, the shape is spherical or quasi-spherical, the thickness of the connecting layer is 5-10 microns, metal or non-metal oxides are lead, antimony, calcium, magnesium, Zinc, platinum, rhodium, ruthenium, nickel, chromium, palladium, boron, One or more of phosphorus oxides, the organic binder is ethyl cellulose, the organic solvent is carbitol, and the additives include surfactants, thixotropic agents, defoamers, dispersants, and sintering. Inhibitor, oxidation inhibitor, expansion inhibitor, composite electrode material used in the preparation of the front electrode, the temperature reaches 100 ° C -500 ° C, the connection layer 8 after drying and curing is sticky at this time;

The paste of the invention has excellent coating effect and can be stably and evenly coated on the surface of the conductive core 7. The different components in the conductive paste can promote the uniform and adjustable coating of the paste on the conductive core. 7 surface layer, on the other hand, can promote the bonding strength between the substrate and the conductive wire in the subsequent process, and optimize the electrical contact performance between the substrate and the substrate, and the connecting layer 8 is dried and solidified. , has a certain viscosity at a certain temperature, so that the electrode itself can be firmly attached to the surface of the device;

Compared with the silver paste of screen printing, the composite electrode material of the invention has the appearance of a front electrode of the battery, which has better morphology and plasticity, less shading, and higher conductivity on the other hand. The subdivision of the composite electrode material on its own function is more conducive to further improving and improving the performance from the two aspects of electrical conductivity and contact performance;

The composite electrode material of the invention is simple to use: it is laid at equal intervals according to the designed front electrode pattern and adhered to the front surface of the battery sheet, and then subjected to bonding treatment by infrared or ultrasonic method to make the composite electrode The bonding layer of the material forms a strong alloy bond with the front surface of the battery sheet and excellent electrical connection, so that the front surface fine electrode can be fabricated, and when the film is adhered and adhered to the front surface of the battery sheet, the pressure applied by the screen printing can be avoided. , causing the problem of chip fragmentation;

As shown in FIG. 7, the preparation process of the front electrode of the photovoltaic cell of the embodiment of the invention includes the following steps:

S701 : metal powder, metal or non-metal oxide, organic binder, organic solvent and additive, uniformly mixed to obtain a conductive paste;

S702: the conductive paste is uniformly coated on the surface of the conductive wire, and is cured by flooding to prepare a composite electrode material;

S703: heating the composite electrode material or the battery sheet to a certain temperature, so that the composite electrode material is firmly bonded to the front surface of the battery sheet according to the design pattern, and the bonding treatment is completed; S704: spraying a conductive paste on the surface of the battery sheet to form a main grid line;

S705: The battery piece is placed in a drying furnace and a sintering furnace to be dried/sintered to form a front electrode; the specific steps of the preparation process of the front electrode of the photovoltaic cell of the present invention are:

Step one, preparing a conductive paste: mixing and stirring metal powder, metal or non-metal oxide, organic binder, organic solvent and additive to obtain a conductive paste; in the conductive paste, the mass percentage of the metal powder is 70 -90%, the metal or non-metal oxide content is 1-10% by mass, the organic binder is 1-10% by mass, and the organic solvent is 1-10% by mass. The mass percentage is 1-5%;

Step 2: preparing a composite electrode material: the conductive paste is uniformly coated on the surface of the conductive wire 1 and dried and solidified. The drying and curing temperature of the conductive paste is 50° C.-200° C., and the conductive paste is dried and cured. The thickness of the conductive wire is 3 micrometers to 20 micrometers; the diameter of the conductive filaments is 5 micrometers to 50 micrometers, and the conductive filaments are selected from the group consisting of gold wires, silver wires, copper wires, aluminum wires, silicon aluminum wires, etc., and the conductive wires can also be used. Conductive fibers such as polymer fibers or carbon fibers;

Step 3, heating the battery sheet 2 or the composite electrode material 4 at 100 ° C - 500 ° C, so that the composite electrode material 4 is firmly and firmly bonded to the front surface of the battery sheet 2, and is bonded to form a composite electrode material. In the row, the bonded cell sheet 2 and the composite electrode material 4 are joined to form a bonding interface 5, and the two ends of the composite electrode material bonded to the front surface of the cell sheet and the two sides are 0.5-1.5 mm apart from the front edge of the cell sheet, and the composite electrode The heating of the material 4 or the battery sheet 2 can be achieved by means of thermosonic, infrared or laser, preferably infrared heating;

Step 4, preparing a main gate line on the front side of the battery sheet: spraying the conductive paste on the surface of the battery sheet 2 to form a main gate line 3, the number of main gate lines is 1-10, and the ends of the main grid line are from the edge of the battery 0.5-1.5mm; medium, drying at 200 ° C - 500 ° C, sintering at 500 ° C - 900 ° C, forming a front electrode, forming a bonding interface between the bonded cell sheet and the composite electrode material joint 6;

The composite electrode material used in the invention has viscosity when the temperature reaches 100 ° C - 500 ° C; conductive paste The body is selected from the group consisting of silver paste, copper paste, nickel paste and the like, and the metal powder in the conductive paste has a particle size ranging from 0.1 to 2 μm, and the shape is spherical or quasi-spherical; metal or non-metal oxide It is a mixture of one or more of lead, bismuth, calcium, magnesium, zinc, platinum, rhodium, ruthenium, nickel, chromium, palladium, boron, phosphorus, etc.; the organic binder is selected from ethyl cellulose , acrylic resin, nitrocellulose, phenolic resin and mixtures thereof; the organic solvent is selected from the group consisting of terpineol, carbitol, diethylene glycol ethyl ether and mixtures thereof; additives include surfactants, thixotropic agents, defoaming Agent, dispersant, sintering inhibitor, oxidation inhibitor and expansion inhibitor;

A specific embodiment of the preparation process of the front electrode of the photovoltaic cell of the present invention will be further described with reference to Figs. 2-7.

Example 5

Photovoltaic cell front electrode, follow these steps:

(1) preparing a conductive paste: mixing metal powder, metal or non-metal oxide, organic binder, organic solvent and additive to obtain a conductive paste; in the conductive paste used, the metal powder is silver powder, conductive Silver paste is 5% by weight of conductive silver paste, 5% by metal or non-metal oxide, 5% by organic binder, 5% by organic solvent, 1% by additive, the rest is silver powder, and the particle size of silver powder. The range is 0.1-2 μητ;

(2) Preparation of composite electrode material: the conductive paste is uniformly coated on the surface of the copper wire with a diameter of 10-20 micrometers, and is dried and solidified. The drying and curing temperature of the conductive paste is 50 ° C - 200 ° C, conductive The paste is dried and cured to a thickness of 5 micrometers to 10 micrometers;

(3) heating the cell or composite electrode material at 100 ° C - 500 ° C, so that the composite electrode material is evenly and firmly bonded to the front surface of the cell sheet, thereby completing the bonding process and bonding to the cell sheet. The two ends of the composite electrode material on the front surface are 0.5-1.5 mm away from the front edge of the cell sheet, and the heating of the composite electrode material can be achieved by means of thermosonic, infrared or laser, preferably infrared heating;

(4) Preparing a main grid line on the front side of the cell sheet: spraying a conductive paste on the surface of the cell sheet to form a main gate line, the number of main gate lines is three, and the ends of the main grid line are 0.5-1.5 mm from the edge of the battery. ;

(5) Put the bonded cell sheet into a drying oven and a sintering furnace, and bake at 200-500 ° C Dry, sintered at 500 ° C - 90 (TC, forming a front electrode;

The composite electrode material used has a viscosity when the temperature reaches 100 ° C - 500 ° C, and the metal or non-metal oxide in the conductive paste is lead, antimony, calcium, magnesium, zinc, platinum, rhodium, iridium, nickel, chromium. And one or more of palladium, boron, phosphorus and the like; the organic binder is selected from the group consisting of ethyl cellulose; the organic solvent is selected from the group consisting of diethylene glycol ethyl ether; the additive includes a surfactant, a thixotropic agent , defoamers, dispersants, sintering inhibitors, oxidation inhibitors and expansion inhibitors;

Example 6

The front electrode of the photovoltaic cell, according to the same procedure as in the first embodiment, except that the conductive silver paste in the second embodiment is in the weight percentage of the conductive silver paste, the metal or non-metal oxide accounts for 8%, and the organic binder accounts for 5%. Organic solvent accounts for 5%, additive accounts for 2%, and the rest is silver powder; the number of main grid lines is 5;

Example 7

The front electrode of the photovoltaic cell, according to the same procedure as in the first embodiment, except that the conductive silver paste in the third embodiment is in the weight percentage of the conductive silver paste, the metal or non-metal oxide accounts for 10%, and the organic binder accounts for 1%. Organic solvent accounts for 1%, additive accounts for 1%, and the rest is silver powder; the number of main grid lines is 7;

Example 8

The front electrode of the photovoltaic cell, according to the same procedure as in Example 3, except that the metal powder used in the conductive paste of Example 4 is a mixture of silver powder and nickel powder, and the weight percentage of the conductive paste in the conductive paste, metal or non- Metal oxides accounted for 8%, organic binders accounted for 3%, organic solvents accounted for 3%, additives accounted for 3%, and the balance was a mixture of silver powder and nickel powder. The weight ratio of silver powder to nickel powder was 7:1, silver. The powder and the nickel powder have a particle size ranging from 0.1 to 2 μm; and the conductive filament used is an aluminum wire; the organic solvent used in the conductive paste is carbitol;

Example 9

The front electrode of the photovoltaic cell, according to the same procedure as in the fourth embodiment, except that in the conductive paste used in the embodiment 5, the metal powder is copper powder, and the conductive copper paste is oxidized by metal or non-metal according to the weight percentage of the conductive copper paste. 8%, organic binders accounted for 5%, organic solvents accounted for 5%, additives accounted for 2%, and the rest were copper powder; The composite electrode material has two functions, namely, the function of conducting current and the bonding with the surface of the cell sheet during the process, and then forming a stable alloy bond and electrical combination; the two ends of the composite electrode are separated from the front side of the cell The edge is 0.5mm-1.5mm, avoiding the extension of the composite electrode to the edge etched area, causing leakage of the battery edge;

The invention greatly reduces the width of the fine grid line on the front side of the solar cell, and can prepare a fine grid line having a width of 20-50 micrometers, and the height can reach 15-40 micrometers, and the aspect ratio of the electrode is large; the conductivity of the fine grid line Compared with the conventional silver paste grid line, the electrode resistance can be increased by more than 20%, the electrode resistance is small, and the internal resistance of the battery is small, thereby improving the conversion efficiency of the photovoltaic cell; the invention can prepare a front electrode with small light-shielding area, higher conductivity and low cost. At the same time, the process greatly reduces the occurrence of fragmentation during the preparation process of the front electrode.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

claims

1. A composite electrode material used for the preparation of front electrodes of photovoltaic cells, characterized in that the composite electrode material used for the preparation of front electrodes of photovoltaic cells includes:

A conductive core is provided inside the composite electrode material and a connection layer is provided on the surface of the conductive core. The connection layer is formed by drying and solidifying the conductive paste coated on the surface of the conductive core.

2. The composite electrode material for preparing the front electrode of photovoltaic cells according to claim 1, characterized in that the conductive core is selected from the group consisting of gold wire, silver wire, copper wire, aluminum wire, silicon-aluminum wire, and can also be a polymer Conductive fibers of fiber or carbon fiber with a conductive core diameter of 5 microns to 50 microns.

3. The composite electrode material for preparing the front electrode of photovoltaic cells according to claim 1, characterized in that the thickness of the connection layer is 3 microns to 20 microns, and the conductive paste is selected from silver paste, copper paste, and nickel paste. The paste is made of metal powder, and the drying and curing temperature is 50°C-200°C. The conductive paste includes metal powder, metal or non-metal oxides, organic solvents, organic binders and additives.

4. The composite electrode material used for the preparation of front electrodes of photovoltaic cells according to claim 1, characterized in that the components and weight percentage content of the conductive paste include:

Metal powder 70-90%; Metal or non-metal oxide 1-10%; Organic binder 1-10%; Organic solvent 1-10%; Additive 1-5%.

5. The composite electrode material for preparing the front electrode of photovoltaic cells according to claim 1, characterized in that when the composite electrode material is used to prepare the front electrode, the temperature reaches 100°C-500°C, and after drying and solidification The connecting layer is sticky, and the composite electrode material is used to prepare the front electrode of photovoltaic cells.

6. The composite electrode material for photovoltaic cell front electrode preparation according to claim 3 or 4, characterized in that the particle size of the metal powder is 0.1-2 μm, the shape is spherical or quasi-spherical, and the metal or non-metal oxide It is one or a mixture of several of lead, bismuth, calcium, magnesium, zinc, platinum, tantalum, rhodium, nickel, chromium, palladium, boron and phosphorus oxide;

The organic binder is selected from ethyl cellulose, acrylic resin, nitrocellulose, phenolic resin and their mixtures;

The organic solvent is selected from terpineol, carbitol, diethylene glycol acetic acid and their mixtures; Additives include surfactants, thixotropic agents, defoamers, dispersants, sintering inhibitors, oxidation inhibitors and swelling inhibitors.

7. A process for preparing the front electrode of a photovoltaic cell using the composite electrode material according to any one of claims 1 to 6, characterized in that the preparation process of the front electrode of the photovoltaic cell includes the following steps: Step 1: Preparing a conductive paste : Mix and stir metal powder, metal or non-metal oxide, organic binder, organic solvent and additives to obtain a conductive paste; in the conductive paste, the mass percentage of metal powder is 70-90%, and the metal or The mass percentage of non-metallic oxides is 1-10%, the mass percentage of organic binders is 1-10%, the mass percentage of organic solvents is 1-10%, and the mass percentage of additives is 1-5%;

Step 2: Prepare the composite electrode material: the conductive paste is evenly coated on the surface of the conductive metal wire, and is dried and solidified;

Step 3: Heat the battery sheet or composite electrode material so that the organic binder in the composite electrode material can partially or completely melt and restore its viscosity, so that the composite electrode material can be firmly bonded to the front surface of the battery sheet according to the designed pattern. Completed bonding treatment;

Step 4: Prepare main grid lines on the front side of the battery sheet: Spray conductive paste on the surface of the battery sheet to make main grid lines;

Step 5: Put the battery pieces into a drying furnace and a sintering furnace, dry them at 200°C-500°C, and sinter them at 500°C-900°C to form a front electrode.

8. The process for preparing the front electrode of a photovoltaic cell according to claim Ί, characterized in that the two ends and sides of the composite electrode material laid on the front surface of the cell are 0.5-1.5mm away from the front edge of the cell, and the two main grid lines are The terminal distance is 0.5-1.5mm from the edge of the cell, and the number of main grid lines is 1-10.

9. The process for preparing the front electrode of a photovoltaic cell according to claim 7, characterized in that, in step one, the particle size range of the metal powder is 0.1-2 μm, and the shape is spherical or quasi-spherical; in step three, the composite electrode Heating of materials or cells can be achieved by thermo-ultrasound, infrared or laser. Infrared heating is preferred, and the heating temperature is 80°C-500°C.

10. The process for preparing the front electrode of a photovoltaic cell according to claim 7, characterized in that, In step two, the diameter of the conductive wire is 5 microns to 50 microns, the thickness of the conductive paste after drying and curing is 3 microns to 20 microns, and the drying and curing temperature of the conductive paste is 50°C-200°C.