CN115810679B

CN115810679B - Back contact battery and electrode structure thereof

Info

Publication number: CN115810679B
Application number: CN202310048106.8A
Authority: CN
Inventors: 林楷睿
Original assignee: Golden Solar Quanzhou New Energy Technology Co Ltd
Current assignee: Golden Solar Quanzhou New Energy Technology Co Ltd
Priority date: 2023-01-31
Filing date: 2023-01-31
Publication date: 2023-04-28
Anticipated expiration: 2043-01-31
Also published as: CN115810679A

Abstract

The invention belongs to the field of back contact batteries, and particularly relates to a back contact battery and an electrode structure thereof, wherein the electrode structure comprises: a third gate line disposed on the first polarity region in the both side regions; a fourth gate line disposed on the second polarity region in the both side regions; the third main grid and a third Pad point arranged on the third main grid are electrically connected with the third grid line, and a first interval is reserved between the third main grid and the edge of the first side area and between the third Pad point and the edge of the first side area; the fourth main grid and a fourth Pad point arranged on the fourth main grid are electrically connected with the fourth grid line, and a second interval is reserved between the fourth main grid and the edge of the fourth Pad point and the edge of the second side area; third grid lines and fourth grid lines which are alternately arranged are distributed on the X axis and the Y axis of the plane where the corresponding main grid is located in the two side areas. The invention has the characteristics of low requirements on the conductivity of the grid line, high battery yield and high welding yield, can improve the reliability of the back contact battery, reduce the cost and ensure excellent photoelectric conversion efficiency.

Description

Back contact battery and electrode structure thereof

Technical Field

The invention belongs to the technical field of back contact batteries, and particularly relates to a back contact battery and an electrode structure thereof.

Background

The back contact solar cell is a cell in which an emitter and a base contact electrode are both arranged on the back (non-light-receiving surface) of the cell, and the light-receiving surface of the cell is free of any metal electrode shielding, so that the short-circuit current of a cell sheet is effectively increased, and meanwhile, a wider metal grid line can be allowed to reduce the series resistance on the back, so that the filling factor is improved; and the front-side non-shielding battery has high conversion efficiency and more attractive appearance, and meanwhile, the assembly of the all-back electrode is easier to assemble. For back contact solar cells, the electrode pattern design is a cell core technology.

The electrode structure of the existing back contact solar cell has the following structures:

in the first specific structure, as shown in fig. 1, the main grids (main grid a 011, main grid B021) of the opposite electrode and the Pad points (Pad points a 012, pad points B022) arranged thereon are respectively designed at the two side edges of the battery (i.e., the main grid and the Pad points thereof are arranged along the edges of the two side regions), the carriers need to be transferred from one side of the battery to the other side, and the lengths of the fine grids (fine grids a 010, B020) for collecting the carriers are very long. The long-distance carrier transmission has very high requirements on the conductivity of the thin grid, and taking a copper grid line as an example, the total area of the thin grid generally occupies more than 80% of the area of the back surface of the battery, and meanwhile, the thickness of the copper grid needs to be more than 30 mu m, so that the double-sided rate of the battery is greatly reduced, and the productivity of copper grid electrode equipment is seriously influenced.

In the second specific structure, as shown in fig. 2, after forming the alternately arranged opposite electrode fine grids (fine grids a 010, fine grids B020), the alternately arranged insulating ink (ink a013, ink B023) is printed on the upper surface of the electrode fine grid, and then the silver paste is printed to form the main grid (main grid a011, main grid B021) and Pad dots (Pad dots a 012, pad dots B022) thereon. In order to avoid short circuit between the main grid and the Pad points and the fine grid, the insulating ink is generally required to be printed to be more than 30 mu m, the insulating ink is not resistant to high temperature, and expensive low-temperature silver paste is required to be used for printing silver paste for forming the main grid and the Pad points, so that the cost of the electrode is greatly increased, and meanwhile, the reliability risk of the battery exists.

In the third specific structure, as shown in fig. 3, the main grids (main grid a011, main grid B021) of the opposite electrode and the Pad points (Pad points a 012, pad points B022) thereon are respectively designed at the middle and two side edges of the battery (i.e. the main grid and the Pad points thereof are arranged along the edges of the two side regions), and the thin grids (thin grid a 010, thin grid B020) are disconnected at the opposite main grid and the Pad point regions. In the assembly manufacturing process, the welding strip also needs to cover the main grid and Pad points at the edge of the silicon wafer, a large number of hidden cracks exist at the edge of the silicon wafer, stress concentration can be caused in the welding process of the welding strip, the problem of cracking occurs, the assembly yield is reduced, and the assembly reliability is reduced.

Therefore, there is an urgent need in the art to study an electrode structure of a back contact battery to solve the above-mentioned problems, which has been one of the important studies by those skilled in the art.

Disclosure of Invention

The invention aims to overcome the defects of high requirements on the conductivity of a grid line, low component yield and component reliability and high material cost of an electrode structure in the prior art, and provides a back contact battery and an electrode structure thereof.

In order to achieve the above object, in a first aspect, the present invention provides an electrode structure of a back contact battery, the electrode structure being provided on a back surface of the back contact battery, the back surface being divided into a middle region and two side regions in an X-axis direction of a plane in which the back surface is located, the electrode structure comprising:

a third gate line disposed on the first polarity region in the both side regions for collecting current of the first polarity region in the both side regions;

a fourth gate line disposed on the second polarity region in the both side regions for collecting current of the second polarity region in the both side regions; and the second polarity is opposite to the first polarity;

The third main grid and a third Pad point arranged on the third main grid are electrically connected with the third grid line, and are arranged at the non-edge of the first side area in the two side areas, and a first interval is reserved between the third main grid and the edges of the third Pad point and the first side area;

the fourth main grid and a fourth Pad point arranged on the fourth main grid are electrically connected with the fourth grid line, and are arranged at the non-edge of the second side area in the two side areas, and a second interval is reserved between the fourth main grid and the edges of the fourth Pad point and the second side area;

third grid lines and fourth grid lines which are alternately arranged are distributed between edges of the first side area and the second side area corresponding to the main grid and the two side areas in the X-axis direction and the Y-axis direction of the plane where the back surface is located, and the fourth grid lines and the third grid lines are respectively provided with edge sections which extend in a bending mode at a first interval and a second interval of the two side areas.

In some preferred embodiments, the curved extension includes at least one of an L-shaped extension, a U-shaped extension, a V-shaped extension, a T-shaped extension, an arcuate extension.

In some preferred embodiments, at the first interval and/or the second interval, the third gate lines and the fourth gate lines alternately arranged are symmetrically distributed along the vertical central line of the corresponding main gate in the two side regions.

In some preferred embodiments, the third main gate, the fourth main gate and the main gate disposed in the middle region are all horizontal to the edge lines of the two side regions in the Y-axis direction.

In some preferred embodiments, the widths of the third and fourth main gates are each independently 1-2 times the width of the main gate disposed in the intermediate region.

In some preferred embodiments, the shortest distance D of the first and second intervals in the X-axis direction is each independently 1-15 mm, preferably 1-7mm.

In some preferred embodiments, the shortest distance d between the end of the corresponding main gate and the side of the corresponding side region in the Y-axis direction is 1-15 mm.

In some preferred embodiments, the shortest distance L between the outermost third or fourth gate line and the edge or side of the respective side region in the X-axis direction and/or Y-axis direction is 0.01-1 mm, preferably 0.01-0.3 mm, in the two side regions.

Preferably, both D and D are greater than L.

In some preferred embodiments, the length of the different third and/or fourth gate lines with the edge sections extending in a curved shape increases gradually and the width widens gradually in the edge direction from the inside to the outside near the two side regions.

More preferably, in the different third and/or fourth gate lines having edge sections extending in a curved shape, the width of the respective gate line is increased by 1-4 times, preferably 2-4 times, compared to the width of the adjacent shorter gate line for each 1-fold increase in the length of the respective gate line.

In some preferred embodiments, the width of the third gate line having edge sections extending in a curved shape and the fourth gate line having edge sections extending in a curved shape are each independently 1 to 6 times, preferably 2 to 6 times, the width of the gate line provided in the intermediate region.

In some preferred embodiments, the first side area and the second side area are respectively provided with a plurality of side electrode units, the plurality of side electrode units are sequentially arranged in the Y-axis direction, and the side electrode units are unit structures formed by the third grid line, the fourth grid line, the third main grid and third Pad points arranged on the third grid line, the fourth main grid and fourth Pad points arranged on the fourth main grid line.

In some preferred embodiments, the electrode structure further comprises:

a first gate line disposed on the first polarity region within the middle region for collecting current of the first polarity region of the middle region;

a second gate line disposed on the second polarity region within the middle region for collecting current of the second polarity region of the middle region;

The first main grid and a first Pad point arranged on the first main grid are arranged in the middle area and are electrically connected with the first grid line;

the second main grid and a second Pad point arranged on the second main grid are arranged in the middle area and are electrically connected with the second grid line;

the first main grid and the second main grid are adjacent and arranged in pairs in the middle area, and the first grid lines and the second grid lines are alternately arranged between the first main grid and the second main grid.

Further preferably, the first gate line and the second gate line have the same width, and the third gate line and the fourth gate line have the same width.

More preferably, the distance between adjacent third and fourth gate lines is 0.1-0.6mm, preferably 0.3-0.5mm, and the distance between adjacent first and second gate lines is 0.1-0.6mm, preferably 0.3-0.5mm.

Further preferably, the sum of the total areas occupied by the first grid line and the second grid line, the third grid line and the fourth grid line on the back surface occupies 8% -30% of the area of the back surface, and the thicknesses of the first grid line and the second grid line, the third grid line and the fourth grid line are 5-10 μm respectively.

More preferably, the first main gate and the second main gate are both horizontal to edge lines of two side areas in the Y-axis direction, a fourth gate line in the first side area is electrically connected to the adjacent second main gate and second Pad point, and a third gate line in the second side area is electrically connected to the adjacent first main gate and first Pad point; the first Pad point and the second Pad point respectively comprise a left Pad point and a right Pad point, and the left Pad point and the right Pad point are distributed in bilateral symmetry or oblique symmetry with the corresponding main grid as the center.

More preferably, the number of the first main grids is the same as the number of the second main grids, and the number of the first main grids is 3-10; the number of the first Pad points on the first main gate is 10-100, and the number of the second Pad points on the second main gate is the same.

More preferably, a plurality of intermediate electrode units are disposed in the intermediate region, and the plurality of intermediate electrode units are sequentially arranged along the X-axis direction and/or the Y-axis direction of the back surface, and the intermediate electrode units are unit structures formed by the first grid line, the second grid line, the first main grid, the first Pad points disposed thereon, the second main grid, and the second Pad points disposed thereon.

In a second aspect, the present invention provides a back contact battery, the back side of which is provided with an electrode structure comprising the first aspect.

The beneficial effects are that:

according to the technical scheme, the third grid lines and the fourth grid lines which correspond to the main grids and are alternately distributed around the main grids are arranged at the non-edges of the two side areas, and other technical characteristics are matched; according to the first aspect, a certain safety distance is kept between the edges of the battery and the main grids corresponding to the two side areas, so that the problem that a large amount of hidden cracks occur in the welding of the edges of the battery is avoided; in the second aspect, the length of the two side areas corresponding to the main grid can be reduced, so that the battery efficiency is improved; in the third aspect, the electrode structure containing each main grid can be realized without printing insulating glue, the requirement on the conductivity of the grid line is reduced, and the battery yield and the welding yield are high. The invention has the characteristics of low requirements on the conductivity of the grid line, high battery yield and high welding yield, can improve the reliability of the back contact battery, reduce the cost and ensure excellent photoelectric conversion efficiency.

In the preferred scheme of the invention, the structure comprising the first main grid and the second main grid is arranged in the middle area and is matched with the third main grid and the fourth main grid in the two side areas together to form a multi-main-grid electrode structure, insulating glue is not required to be printed on the electrode structure in a large area, the multi-main-grid electrode structure without main grids and Pad points at the two side edges of the battery is realized, and current is not required to be transmitted to long-distance grid lines and is converged to the main grid areas, so that the requirement on the conductivity of the grid lines is remarkably reduced, the reliability of the back contact battery is further improved, the cost is reduced, and the product yield is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic view of a first electrode structure part of the prior art.

Fig. 2 is a schematic diagram of a second electrode structure portion of the prior art.

Fig. 3 is a schematic view of a third electrode structure portion of the prior art.

Fig. 4 is a schematic structural view of a first embodiment of the electrode structural part of the present invention.

Fig. 5 is a schematic diagram of the structure of fig. 4 after dividing the area.

Fig. 6 is a schematic structural view of a second embodiment of the electrode structural part of the present invention.

Fig. 7 is a schematic view of the structure of an embodiment of the middle region of the electrode structure of the present invention.

Fig. 8 is a schematic structural view of a third embodiment of the electrode structural portion of the present invention.

Fig. 9 is a schematic view showing a specific structure of the whole electrode structure of the present invention.

Description of the reference numerals

011. Master bars a,021, master bars B,012, pad points a,022, pad points B,010, fine bars a,020, fine bars B,013, ink a,023, ink B.

10. A first grid line, 20, a second grid line, 30, a third grid line, 40, a fourth grid line, 11, a first main grid, 12, a first Pad point, 21, a second main grid, 22, a second Pad point, 31, a third main grid, 32, a third Pad point, 41, a fourth main grid, 42 and a fourth Pad point; A. middle region, B, second side region, C, first side region.

Detailed Description

In the present invention, unless otherwise indicated, terms of orientation such as "upper, lower, left, right" and the like are used generally to refer to the orientation as shown in the drawings and in practice. In the invention, the direction of the edge close to the two side areas of the back of the battery is taken as the outside, and the opposite direction is taken as the inside.

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.

The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein. Wherein the terms "optional" and "optionally" mean either comprising or not comprising (or may not be present).

In a first aspect, the present invention provides an electrode structure of a back contact battery, the electrode structure being disposed on a back surface of the back contact battery, the back surface being divided into a middle region and two side regions in an X-axis direction of a plane in which the back surface is located, the electrode structure comprising:

and the fourth main grid and a fourth Pad point arranged on the fourth main grid are electrically connected with the fourth grid line, and are arranged at the non-edge of the second side area in the two side areas, and a second interval is reserved between the fourth main grid and the edges of the fourth Pad point and the second side area.

According to the invention, the back surface is divided into the middle area and the two side areas along the X-axis direction, and the electrode distribution in the two side areas is improved, especially, the main grids in the two side areas are arranged at the non-edges and matched with the specific grid line extending structure, so that the problems that in the prior art, the requirements on grid line conductivity are very high, the double-sided rate of a battery is low, the thickness of a copper grid electrode is very thick, welding strips are required in the process of manufacturing components by the main grids and the Pad points at the two side edges of the battery, and a large number of hidden cracks exist, thereby reducing the problems of component yield, component reliability and the like, and improving the battery conversion efficiency, the battery yield, the battery reliability and the like.

In the present invention, the edges of the side regions refer to the complete edge lines (or referred to as edge lines in the Y-axis direction of the back) on the side regions of the back, while the adjacent edges (i.e., edge portions in the X-axis direction) on the side regions are referred to as partial edges or side edges.

In the present invention, in the X-axis and Y-axis directions of the plane where the back surface is located, the third and fourth grid lines are alternately arranged between the edges of the corresponding main grid and the two side regions in the first and second side regions, that is, between the outer side surface of the corresponding main grid of the two side regions of the back surface of the battery and the edge of the adjacent corresponding side region (i.e., -X-axis direction), between the inner side surface of the corresponding main grid of the two side regions and the middle region (i.e., + X-axis direction), and between the two ends of the corresponding main grid of the two side regions and the side edges of the adjacent corresponding side regions (i.e., -Y-axis and +y-axis directions), a plurality of third and fourth grid lines are alternately arranged, as shown in fig. 4. It can be understood that the third grid lines and the fourth grid lines which are alternately arranged are distributed around the corresponding main grid in the two side areas (namely, in the upper, lower, left and right directions of the plane where the main grid is located).

Preferably, the third main gate and the fourth main gate are respectively located at the middle of the two side regions in the Y-axis direction. That is, both ends of the third main grid or the fourth main grid are the same distance to the upper and lower sides of the both side regions, respectively, in the Y-axis direction (i.e., in the vertical direction in fig. 4).

In the present invention, the second polarity is opposite to the first polarity, and thus the first polarity is negative when the second polarity is positive and the second polarity is negative when the first polarity is positive.

In some preferred embodiments, the curved extension includes at least one of an L-shaped extension, a U-shaped extension, a V-shaped extension, a T-shaped extension, an arcuate extension (including curved combinations of any curvature, circular, non-circular, etc.). Wherein the curved extension may be one or a combination of the above-mentioned extensions. Under the preferred scheme, the corresponding main grids and the corresponding Pad points of the two side areas are more beneficial to being arranged away from the edges of the two side areas of the battery, so that the requirement on the conductivity of the grid line is further remarkably reduced, and meanwhile, the reliability of the back contact battery is further improved, the cost is reduced, and the product yield is improved.

The curved extension is more preferably at least one of an L-shaped extension, a U-shaped extension, a T-shaped extension.

In some preferred embodiments, at the first interval and/or the second interval, the third gate lines and the fourth gate lines alternately arranged are symmetrically distributed along the vertical central line of the corresponding main gate in the two side regions. In one embodiment, as shown in fig. 4, the third gate lines 30 and the fourth gate lines 40 are alternately distributed in a concave shape. Of course, in other embodiments, the third gate lines and the fourth gate lines that are alternately arranged may be distributed asymmetrically along the vertical central lines of the corresponding main gates in the two side regions.

In the present invention, the third main gate and the third Pad points set on the third main gate means that a plurality of third Pad points are set on the third main gate. Typically, a plurality of third Pad points are spaced apart along the axis of the third primary grating. The fourth main gate and the fourth Pad point disposed thereon have the same definition and are not described herein.

In the invention, the homopolar grid lines in the two side areas are electrically connected with the corresponding homopolar main grids and the corresponding Pad points arranged on the homopolar main grids, the end parts of the different-polarity grid lines near the main grids are free ends, and the other ends of the different-polarity grid lines are electrically connected with the nearest homopolar main grids in the middle area and the corresponding Pad points. It will be appreciated that the free end is spaced from, unconnected to, or otherwise known as a different polarity gate line, from the main gate. As shown in fig. 5, the back electrode structure is divided into a middle area a, a first side area C and a second side area B, the fourth gate line 40 of the second side area B is electrically connected to the fourth main gate 41 and the fourth Pad point 42, one end of the third gate line 30 of the second side area B, which is close to the fourth main gate 41 and the fourth Pad point 42, is a free end, a distance is reserved between the free end and the fourth main gate 41 and the fourth Pad point 42, and the other end of the third gate line 30 is electrically connected to the closest homopolar main gate in the middle area a; the third gate line 30 of the first side area C is electrically connected to the third main gate 31 and the third Pad point 32, one end of the fourth gate line 40 of the first side area C, which is close to the third main gate 31 and the third Pad point 32, is a free end, a distance is left between the free end and the third main gate 31 and the third Pad point 32, and the other end of the fourth gate line 40 is electrically connected to the closest homopolar main gate in the middle area a.

More preferably, the widths of the third main gate and the fourth main gate are each independently 1 to 2 times, specifically, for example, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2 times the widths of the main gates provided in the intermediate region. Under the preferred scheme, the third main grid and the fourth main grid are wider than the main grid in the middle area, so that more carriers can be collected, and the electric power loss of the carriers on the main grid can be reduced more conveniently.

In some particularly preferred embodiments, the widths of the third and fourth main gates are each independently 1 to 1.5 times the width of the main gate disposed in the intermediate region.

On the basis of meeting the specific multiple of the width, the widths of the third main grid and the fourth main grid and the widths of the main grids arranged in the middle area are wide in feasible range, and the widths of the third main grid and the fourth main grid are respectively and independently 0.2-0.5mm and the widths of the main grids arranged in the middle area are respectively and independently 0.1-0.3mm. Wherein the widths of the third main gate and the fourth main gate are the same or different, preferably the same.

In some preferred embodiments, the shortest distance D of the first interval and the second interval in the X-axis direction is each independently 1-15 mm, and specifically may be, for example, 1mm, 2mm, 5mm, 7mm, 10mm, 12mm, 14mm, 15mm, etc., and any value between adjacent point values. Under the preferred scheme, the third main grid and the corresponding Pad points thereof and the fourth main grid and the corresponding Pad points thereof are simultaneously arranged in the safe area for edge welding of the areas on two sides of the silicon wafer, so that the possibility of micro hidden cracking of the edge welding of the silicon wafer is avoided, the length of the areas on two sides of the silicon wafer corresponding to the main grid can be reduced, and the battery efficiency is further improved.

In some particularly preferred embodiments, the shortest distance D of the first and second intervals in the X-axis direction is each independently 1-7 mm.

In the present invention, the shortest distance D between the first interval and the X axis is the distance between the third main gate and the third Pad point and the edge of the first side area, that is, the distance between the third main gate and the edge of the first side area, in the X axis direction, and the distance between the third Pad point and the edge of the first side area is within 1-15 mm. The shortest distance D of the second interval in the X-axis direction has a similar definition and will not be described here.

In the invention, under the condition that the distance between the corresponding main grid in the two side areas and the edges of the two side areas is determined, the relative size of the corresponding Pad points arranged on the corresponding main grid relative to the corresponding main grid can be determined by a person skilled in the art according to actual requirements; illustratively, the Pad points extend outwardly in the width direction (i.e., the X-axis direction) of their corresponding primary gate by a distance of 0.2-1mm, i.e., the distance between the outermost edge of the Pad point and the outermost edge of the corresponding primary gate.

In some preferred embodiments, the shortest distance d between the end of the corresponding main grid and the side of the corresponding side region in the Y-axis direction is 1-15 mm, and specifically may be, for example, 1mm, 2mm, 5mm, 7mm, 10mm, 12mm, 14mm, 15mm, etc. and any value between adjacent point values. Under the preferred scheme, as the end part of the main grid is kept at a certain distance from the side edge of the silicon wafer, the corresponding main grid and the corresponding Pad points of the two side areas are more beneficial to being arranged away from the edges of the two side areas of the battery.

In some preferred embodiments, the shortest distance L between the outermost third or fourth gate line and the edge or side of the corresponding side region in the X-axis direction and/or Y-axis direction is 0.01-1 mm in the side regions. Under the preferred scheme, as the distance L between the grid lines and the edges or the sides is obviously smaller than the corresponding L of the main grid, the grid lines adjacent to the outermost grid lines and with opposite polarities are more beneficial to collect carriers, so that the efficiency of the battery is improved.

The L is 0.01 to 1mm, and may be, for example, 0.01mm, 0.05mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, etc., and any value between adjacent spot values, and in some particularly preferred embodiments is preferably 0.01 to 0.3 mm.

Wherein the shortest distance L between the outermost third or fourth gate line and the edge (or side) of the corresponding side region in the X-axis direction may be the same or different from the corresponding distance L in the Y-axis direction.

In the present invention, both D and D are greater than L.

In some more preferred embodiments, the shortest distance D between the first and second intervals in the X-axis direction is each independently 1 to 15 mm, and the shortest distance L between the outermost third or fourth grid line and the edge or side of the corresponding side region in the X-axis direction is 0.01 to 1mm in the both side regions; and D is greater than L. Under the preferred scheme, the distribution distance between the grid lines positioned at the edges and the main grid positioned at the non-edges in the two side areas is proper, and the electric power loss conducted by carriers on the grid lines is reduced, so that the battery efficiency is improved.

In some preferred embodiments, the first side area and the second side area are respectively provided with a plurality of side electrode units, the plurality of side electrode units are sequentially arranged along the Y-axis direction, and the side electrode units are unit structures formed by the third grid line, the fourth grid line, the third main grid and third Pad points arranged on the third grid line, the fourth main grid and fourth Pad points arranged on the fourth main grid line. In a specific embodiment, as shown in fig. 8, several side electrode units are sequentially arranged, and it can be understood that the corresponding main grids in the upper and lower adjacent side electrode units are in a discontinuous structure in the figure.

In some preferred embodiments, the length of the different third and/or fourth gate lines with the edge sections extending in a curved shape increases gradually and the width widens gradually in the edge direction from the inside to the outside near the two side regions. Under the preferred scheme, the length of the grid line of the edge section, which is in the bent extension in the part of the first interval and the second interval in the two side areas, is longer than the length of the corresponding grid line in the middle area, and the width of the corresponding grid line, which is in the bent extension in the two side areas, is increased in a matching way, so that the electric transmission loss caused by the longer length of the grid line is reduced more effectively.

The gradual widening of the width includes at least one of the following three aspects: in the edge direction from inside to outside near the two side areas, the widths of the different third grid lines with the edge sections are gradually widened in the first aspect, and in the second aspect, the widths of the different fourth grid lines with the edge sections are gradually widened, namely, the widths of the adjacent two third grid lines are different, the widths of the adjacent two fourth grid lines are different, and the widths of the corresponding grid lines are wider as the adjacent two fourth grid lines are closer to the edges of the two side areas; in a third aspect, the widths of the third gate line having the edge section extending in a curved shape and the adjacent fourth gate line having the edge section extending in a curved shape are gradually widened in the above-described direction. The gradual increase in length has the same explanation as the gradual widening of the width for the corresponding three aspects, which will not be described again here.

More preferably, in the different third and/or fourth gate lines with curved extending edge sections, the width of the respective gate line increases by a factor of 1-4 compared to the width of the adjacent shorter gate line, in particular by a factor of 1, 1.5, 2, 2.5, 3, 3.5, 4, and any value between its adjacent point values, preferably by a factor of 2-4. Under the preferred scheme, the width is increased appropriately, so that the electric transmission loss caused by longer grid line length is reduced effectively, and the battery conversion efficiency is improved.

In some preferred embodiments, the width of the third gate line having the edge section extending in a curved shape and the fourth gate line having the edge section extending in a curved shape are each independently 1 to 6 times the width of the gate line provided in the intermediate region, and specifically may be, for example, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 times any value between the adjacent dot values thereof, as shown in fig. 6. Under the preferred scheme, the width of the grid lines of the edge sections extending in a bending shape in the two side areas is the same as or wider than the corresponding width of the grid lines in the middle area, and the wider scheme is more beneficial to effectively reducing the electric transmission loss caused by longer length of the grid lines in the two side areas.

In some particularly preferred embodiments, the width of the third gate line having edge sections extending in a curved shape and the fourth gate line having edge sections extending in a curved shape are each independently 2 to 6 times the width of the gate line provided in the intermediate region.

In the above preferred embodiment, it should be understood that the widths of the third and fourth gate lines having the edge sections extending in a curved shape may each independently be 1 to 6 times the width of the corresponding gate line of the middle region, while the widths of the corresponding gate lines of the middle region are the same; when the widths of the corresponding grid lines in the middle area are different, the widths of the third grid line or the fourth grid line with the bent extending edge sections are respectively in a 1-6 times range with the widths of the corresponding grid lines in the middle area. The former is preferred.

The widths of the different third grid lines with the edge sections extending in a bending mode can be the same or different, the widths of the different fourth grid lines with the edge sections extending in a bending mode can be the same or different, and the widths of the third grid lines with the edge sections extending in a bending mode and the adjacent fourth grid lines with the edge sections extending in a bending mode can be the same or different; so long as the battery performance, yield, cost and other effects are improved.

Further preferably, the third gate line having the edge section extending in a curved shape and the fourth gate line having the edge section extending in a curved shape are each identical in width, and the corresponding gate lines in the intermediate region are identical in width.

In a preferred embodiment of the present invention, the widths of the third and fourth gate lines having no curved edge sections in the both side regions are the same as the widths of the corresponding gate lines in the middle region.

In some preferred embodiments, the electrode structure further comprises:

It is understood that the polarity of the corresponding gate line or the corresponding main gate disposed on the first polarity region is the same as the first polarity, and the polarity of the corresponding gate line or the corresponding main gate disposed on the second polarity region is the same as the second polarity; for example, when the first polarity is positive, the first gate line and the third gate line are positive gate lines for collecting positive current in the first polarity region, and the second gate line and the fourth gate line are negative gate lines for collecting negative current in the second polarity region; or when the first polarity is negative, the first grid line and the third grid line are negative grid lines for collecting the negative current of the first polarity region, and the second grid line and the fourth grid line are positive grid lines for collecting the positive current of the second polarity region. It should be understood that the positive electrode grid line is arranged in the P-type doped region at the back of the back contact battery, and the negative electrode grid line is arranged in the N-type doped region at the back of the back contact battery. Specifically, in one embodiment, as shown in fig. 4 to 8, for convenience of discrimination, the first gate line 10 and the third gate line 30 of the grid filling portion have the same polarity, the second gate line 20 and the fourth gate line 40 of the black filling portion have the same polarity, and the polarities of the first gate line 10 and the third gate line 30 are opposite to the polarities of the second gate line 20 and the fourth gate line 30; the first main grid 11, the first Pad point 12, the third main grid 31 and the third Pad point 32 of the grid filling part have the same polarity as the first grid line 10 and the third grid line 30; the second main gate 21, the second Pad dot 22, the fourth main gate 41, and the fourth Pad dot 42 of the black filled portion have the same polarity as the second gate line 20 and the fourth gate line 40.

More preferably, the first main gate and the second main gate are both horizontal to edge lines of both side regions in the Y-axis direction.

More preferably, the distance between the adjacent third and fourth gate lines is 0.1-0.6mm, and the distance between the adjacent first and second gate lines is 0.1-0.6mm. Further preferably, a distance between adjacent third and fourth gate lines is 0.3-0.5mm, and a distance between adjacent first and second gate lines is 0.3-0.5mm.

In some preferred embodiments, the sum of the total area occupied by the first and second, third and fourth gate lines on the back surface is 8% -30% of the back surface area.

In some preferred embodiments, the thicknesses of the first and second, third and fourth gate lines are each independently 5-10 μm.

In the invention, corresponding grid lines in two side areas are connected to adjacent homopolar main grids in a middle area and Pad points arranged on the homopolar main grids. In a specific embodiment of the present invention, the fourth gate line in the first side region is electrically connected to the adjacent second main gate and the second Pad point, and the third gate line in the second side region is electrically connected to the adjacent first main gate and the first Pad point. The fourth grid line in the first side area can be electrically connected to the adjacent second main grid with the same polarity, can also be electrically connected to the second Pad point, and the third grid line is similar.

In the present invention, preferably, the first Pad point and the second Pad point respectively include a left Pad point and a right Pad point, and the left Pad point and the right Pad point are distributed in bilateral symmetry or oblique symmetry with the corresponding main grid as a center. Under the preferred scheme, the electric connection between the corresponding grid lines in the two side areas with the shortest distance is more convenient.

In one embodiment of the above preferred embodiment, as shown in fig. 4, the first Pad point 12 includes a left Pad point and a right Pad point, which are symmetrically distributed about the first main grid 11 connected to the first Pad point 12; the second Pad point 22 includes a left Pad point and a right Pad point, which are distributed diagonally symmetrically about the second main grid 21 connected to the second Pad point 22.

In the invention, the end parts of the grid lines with different polarities, which are arranged near the corresponding main grid in each area, are free ends, namely the grid lines with different polarities are disconnected and disconnected at the positions of the adjacent corresponding main grid and Pad points, whether in the two side areas or in the middle area; that is, in the present invention, each corresponding gate line satisfies: one end is a free end, and the other end is electrically connected to the similar main grid and Pad points with the same polarity; the electric connection parts between the grid lines and the main grid are all connected with the same polarity, so that the mutual overlapping points of the grid lines and the main grid with different polarities are not existed, and the insulating ink required at the overlapping points as shown in fig. 2 is not arranged.

In the invention, the number of the first main grids can be more than or equal to 1. It will be appreciated that in the intermediate region, the first main gate is arranged in pairs with the adjacent second main gate.

The number of the first main grids is the same as that of the second main grids, and more preferably, the number of the first main grids is 3-10. In this preferred embodiment, the first main gate and the second main gate are alternately arranged, and the length thereof may be extended according to the back surface size.

It is further preferred that the number of first Pad points on the first main gate is the same as the number of second Pad points on the second main gate, and more preferred that the number of first Pad points on the first main gate is 10-100.

More preferably, as shown in fig. 7 to fig. 8, a plurality of intermediate electrode units are disposed in the intermediate area, and the plurality of intermediate electrode units are sequentially arranged along the X-axis direction and/or the Y-axis direction of the back surface, where the intermediate electrode units are unit structures formed by the first gate line, the second gate line, the first main gate, the first Pad point disposed thereon, the second main gate, and the second Pad point disposed thereon.

It will be appreciated that a pair of first and second main grids are included in the intermediate electrode unit, as well as other corresponding structures disposed and connected thereto. When the plurality of intermediate electrode units are sequentially arranged in the X-axis direction, as shown in fig. 7; when the plurality of intermediate electrode units are sequentially arranged in the Y-axis direction, as shown in fig. 8; when several intermediate electrode units are arranged in sequence along the X-axis direction and the Y-axis direction, the whole is shown in fig. 9. It can be understood that, in the two middle electrode units in the Y-axis direction, the first main grids adjacent to each other vertically or the second main grids adjacent to each other vertically are respectively electrically connected to each other and are in a continuous structure, and the fourth grid line or the third grid line on the outermost layer can be arranged in an overlapping manner (i.e. two corresponding grid lines with the same polarity can be arranged in an overlapping manner) or in a common connection manner (i.e. the two middle electrode units are in common in the X-axis direction, and the edge sections extending in a bending manner extend in respective directions).

In the present invention, the other gate lines are arranged in parallel along the X-axis direction on the back surface except for the gate lines arranged in the first and second spaces.

In the present invention, the shape of the back contact battery may be any existing shape, for example, may be rectangular, such as a rectangle or square; the corner may be a quadrangle including corners, for example, corners of the quadrangle may be standard corners, cut corners or rounded corners, etc., which may be set according to actual production needs, and are not particularly limited herein.

In the present invention, the number of each corresponding gate line (including corresponding gate lines of different polarities) disposed on the back surface may be determined by those skilled in the art according to the actual area of the back contact battery, the width of each corresponding gate line, and the above-mentioned required distance, and is not specifically limited herein.

The back contact battery has high production yield, high reliability and low cost, and can ensure excellent photoelectric conversion efficiency.

The invention will be further described in detail with reference to specific examples.

Example 1

An electrode structure of a back contact battery, part of the structural units of which are shown in fig. 4, 5, 7 and 8, and the whole structure of which is shown in fig. 9, comprising:

A first grid line 10 for collecting current of a first polarity in the cell middle region a;

a second grid line 20 for collecting the second polarity current of the cell middle area a;

a third gate line 30 for collecting a current of a first polarity at both side regions B/C of the battery;

a fourth gate line 40 for collecting a second polarity current of the battery in both side regions B/C;

a first main gate 11 and a first Pad point 12 of a first polarity provided in the middle area a of the back surface of the battery, and a second main gate 21 and a second Pad point 22 of a second polarity provided in the middle area a;

a fourth main gate 41 and a fourth Pad dot 42 provided in a second side region B and having a second polarity among both side regions of the back surface of the battery, and a third main gate 31 and a third Pad dot 32 provided in a first side region C and having a first polarity;

the first gate line 10 and the third gate line 30 collect current in a first polarity region, and the second gate line 20 and the fourth gate line 40 collect current in a second polarity region. The polarities of the first polarity region and the second polarity region are opposite, specifically, the first gate line 10 and the third gate line 30 are positive gate lines for collecting positive current in the positive electrode region, and the second gate line 20 and the fourth gate line 40 are negative gate lines for collecting negative current in the negative electrode region. The positive electrode grid line is arranged in the P-type doped region of the back contact battery, and the negative electrode grid line is arranged in the N-type doped region of the back contact battery.

The first Pad point 12 and the second Pad point 22 respectively include a left Pad point and a right Pad point, and the left Pad point and the right Pad point are respectively distributed in bilateral symmetry and oblique symmetry with the corresponding main grid as a center. The number of second Pad points 22 of the second polarity in the middle area a is 20, which are uniformly spaced along the axial direction of the corresponding main grating, the same as the number of first Pad points 12 of the first polarity. The first grid lines 10 of the first polarity and the second grid lines 20 of the second polarity in the middle area A of the battery are alternately and horizontally arranged, and the first grid lines 10 and the second grid lines 20 are respectively arranged perpendicular to the axial direction of the corresponding main grid in the middle area A, and the corresponding main grid in the middle area A is parallel to the edge lines of the areas on the two sides of the battery.

As shown in fig. 4, a plurality of third grid lines 30 with a first polarity and a plurality of fourth grid lines 40 with a second polarity are distributed between the edges of the corresponding main grid and the two side regions of the battery in the two side regions of the back of the battery, the third grid lines 30 and the fourth grid lines 40 are alternately distributed in an L shape and a concave shape (with L-shaped extension, U-shaped extension and T-shaped extension), and are symmetrically distributed along the vertical central line of the corresponding main grid, and the lengths of different third grid lines and different fourth grid lines which are alternately distributed in the L shape and the concave shape are sequentially increased in the edge direction close to the two side regions from inside to outside. The fourth gate line 40 of the second side region B is connected to the fourth main gate 41 and the fourth Pad point 42, and the third gate line 30 of the first side region C is connected to the third main gate 31 and the third Pad point 32.

As shown in fig. 4, the distance L between the edge-most gate lines in the two side regions and the middle region of the back of the cell and the edge or side of the silicon wafer is 0.2mm, and the distance is defined herein as the distance between the third gate line 30 or the fourth gate line 40, the first gate line 10 or the second gate line 20, which are adjacent to the edge-most gate line of the silicon wafer, and the edge or side of the silicon wafer in the two side regions. The distances D between the corresponding main grids and the edges in the two side areas of the back of the battery are 5mm respectively, and the outward extension distances of the corresponding Pad points in the width direction of the corresponding main grids are 0.4mm respectively. The distance d between the end of the corresponding main grid in the two side areas and the side edge of the corresponding side area is 5mm.

The widths of the first gate line 10 and the second gate line 20 are the same as those of the third gate line 30 and the fourth gate line 40, and are all 0.1mm. The first main gate 11 and the second main gate 21 have the same width of 0.2mm, and the third main gate 31 and the fourth main gate 41 have a width 1.2 times the width of the first main gate 11. The distance between the adjacent third grid line and the fourth grid line is 0.4mm, and the distance between the adjacent first grid line and the second grid line is 0.4mm. The sum of the total areas occupied by the first gate line 10, the second gate line 20, the third gate line 30 and the fourth gate line 40 on the back surface occupies 18% of the back surface area, and the thicknesses of the first gate line 10, the second gate line 20, the third gate line 30 and the fourth gate line 40 are all 5 μm.

Example 2

As shown in fig. 6, the difference is that the widths of the third and

fourth gate lines

30 and 40 alternately distributed in the L-shape and the concave-shape on the both side regions are 2 times the width of the first gate line 10 in the middle region a, and the widths of the third and

fourth gate lines

30 and 40 extending straight on the whole of the both side regions are the same as the first and

second gate lines

10 and 20. Accordingly, the sum of the total area occupied by the first gate line 10, the second gate line 20, the third gate line 30 and the fourth gate line 40 on the back surface occupies 22% of the back surface area.

Example 3

The difference with reference to embodiment 2 is that the widths of the third gate lines 30 and the fourth gate lines 40 alternately distributed in the L-shape and the concave-shape on the both side regions are 1.2 times the width of the first gate line 10 of the middle region a. Accordingly, the sum of the total area occupied by the first gate line 10, the second gate line 20, the third gate line 30 and the fourth gate line 40 on the back surface occupies 18.5% of the back surface area.

Example 4

With reference to embodiment 1, the difference is that, in the edge direction near the two side regions from inside to outside, the widths of the different third and fourth grid lines alternately distributed in the L-shape and the concave shape gradually widen with the increase in length in turn, that is, between any adjacent two grid lines among the grid lines alternately distributed in the L-shape and the concave shape, and between the grid line alternately distributed in the L-shape and the concave shape and the corresponding grid line (the third or fourth grid line) extending in a straight line with the adjacent whole, the width of the corresponding grid line increases by 1.1 times compared with the width of the adjacent shorter grid line with each 1 times of the length of the corresponding grid line. Accordingly, the sum of the total area occupied by the first gate line 10, the second gate line 20, the third gate line 30 and the fourth gate line 40 on the back surface occupies 18.5% of the back surface area. The width of the corresponding gate line (third gate line or fourth gate line) extending straight as a whole is the same as the first gate line 10 and the second gate line 20.

Example 5

With reference to example 4, the difference is that the widening gradient is different, in particular, with each 1-fold increase in the length of the corresponding gate line, the width of the corresponding gate line is increased by 4-fold compared to the width of the adjacent shorter gate line. Accordingly, the sum of the total area occupied by the first gate line 10, the second gate line 20, the third gate line 30 and the fourth gate line 40 on the back surface occupies 22% of the back surface area.

Example 6

With reference to example 4, the difference is that the width of the different third gate lines alternately distributed in the L-shape and the concave-shape is widened in gradient, and the width of the gate line of the length is increased by 1.125 times compared with the width of the adjacent shorter gate line with each increase of 1 time of the length of the different third gate lines, which is different from the width of the different fourth gate lines alternately distributed in the L-shape and the concave-shape. Accordingly, the sum of the total area occupied by the first gate line 10, the second gate line 20, the third gate line 30 and the fourth gate line 40 on the back surface occupies 19.5% of the back surface area.

Example 7

The procedure was carried out with reference to example 1, except that the distances D between the corresponding main grids and the edges in the regions on both sides of the back surface of the battery were 10mm, respectively. Accordingly, the sum of the total area occupied by the first gate line 10, the second gate line 20, the third gate line 30 and the fourth gate line 40 on the back surface occupies 18% of the back surface area.

Example 8

The process was performed with reference to example 1, except that the gate line at the most edge in the both side regions of the back surface of the cell was spaced apart from the edge or side edge of the both side regions of the silicon wafer by a distance L of 0.5mm.

Example 9

The process was performed with reference to example 1, except that the gate line at the most edge in the regions on both sides of the back surface of the cell was 1mm from the edge or side of the regions on both sides of the silicon wafer.

Example 10

The process is performed with reference to embodiment 1, except that the widths of the third main gate 31 and the fourth main gate 41 are each 2 times the width of the first main gate 11.

Comparative example 1

An electrode structure is shown in fig. 1, wherein the main grids (main grid A011, main grid B021) of the opposite electrode and the Pad points (Pad points A012, pad points B022) arranged on the main grids are respectively arranged on the edges of the two side regions of the battery and extend along the edges of the two side regions, the main grid and the Pad points are not arranged in the middle, and only the fine grid (fine grid A010, fine grid B020) for collecting carriers is arranged in the middle. The main gate and Pad point and the thin gate have the same widths as those of the main gate and the gate line of embodiment 1, respectively.

In this comparative example, carriers need to be transported from one side of the cell to the other side, and the length of the fine grid (fine grid a 010, fine grid B020) collecting carriers is very long. The long-distance carrier transmission has very high requirements on the conductivity of the thin grid, and taking a copper grid line as an example, the total area of the thin grid generally occupies more than 80% of the area of the back surface of the battery, and meanwhile, the thickness of the copper grid needs to be more than 30 mu m, so that the double-sided rate of the battery is greatly reduced, and the productivity of copper grid electrode equipment is seriously influenced.

Comparative example 2

An electrode structure is shown in fig. 2, after forming alternately arranged opposite electrode fine grids (fine grids A010 and B020), insulating ink (ink A013 and ink B023) is printed on the upper surface of the electrode fine grids, and then silver paste is printed to form main grids (main grids A011 and B021) and Pad points (Pad points A012 and Pad points B022) on the main grids. The main gate and Pad point and the thin gate have the same widths as those of the main gate and the gate line of embodiment 1, respectively.

In this comparative example, in order to avoid short circuit between the main grid and Pad points and the fine grid, the insulating ink generally needs to be printed to 30 μm or more, and the insulating ink is not resistant to high temperature, and the silver paste for printing to form the main grid and Pad points needs to use expensive low-temperature silver paste, so that the cost of the electrode is greatly increased, and meanwhile, the reliability risk of the battery exists.

Comparative example 3

An electrode structure is shown in fig. 3, wherein the main grids (main grid A011, main grid B021) of the opposite electrode and Pad points (Pad points A012, pad points B022) on the main grids are respectively designed at the edges of the middle and two side areas of the battery and extend along the edges, and the thin grids (thin grid A010, thin grid B020) are disconnected in the opposite main grid and Pad point areas. The main gate and Pad point and the thin gate have the same widths as those of the main gate and the gate line of embodiment 1, respectively.

In the comparative example, in the process of manufacturing the component, the welding strip also needs to cover the main grid and Pad points at the edges of the two side areas of the silicon wafer, a large number of hidden cracks exist at the edges of the silicon wafer, stress concentration can be caused in the welding process of the welding strip, the problem of cracking occurs, the yield of the component is reduced, and the reliability of the component is reduced.

Test case

The electrode structures of the above examples and comparative examples were used in back contact batteries, and the battery performance (short circuit current (Jsc), battery conversion efficiency) was tested according to test standard GB/T6495, and the gate line (or fine gate) conductivity requirements, battery yield, and welding yield of the batch were measured and recorded, and the results are shown in table 1.

TABLE 1

Examples numbering	Jsc (mA/cm2)	Conductivity requirement	Yield of battery (%)	Yield of welding (%)	Conversion efficiency of battery (%)
						Example 1	42.3	1.3	98.5	99.8	26.1
Example 2	42.3	1	98.5	99.8	26.1
						Example 3	42.3	1.2	98.5	99.8	26.1
Example 4	42.3	1.25	98.5	99.8	26.1
						Example 5	42.3	1	98.5	99.8	26.1
Example 6	42.3	1.2	98.5	99.8	26.1
						Example 7	42.3	1.5-2	98.5	99.8	26.1
Example 8	42.1	1.3	98.5	99.8	25.98
						Example 9	41.9	1.3	98.5	99.8	25.85
Example 10	42.2	1.3	98.5	99.8	26.05
						Comparative example 1	42.45	10-100	98.2	99.5	26.05
Comparative example 2	42.5	0.5	95	97	26.2
						Comparative example 3	42.2	1	98.5	95	25.8

As can be seen from the above results, compared with the comparative example, the back contact battery multi-main gate electrode structure of the present invention has the characteristics of low requirements on the conductivity of the gate line, high battery yield, and high welding yield, and can improve the reliability of the back contact battery, reduce the cost, and ensure excellent photoelectric conversion efficiency.

Further, according to embodiment 1 and embodiment 2, it can be seen that, by adopting the preferred scheme of the present invention for widening the width of the gate line with larger length of the two side regions, the requirement on the conductivity of the gate line is lower, thereby being more beneficial to mass production and lower in cost. As can be seen from examples 2 and 3, the requirement for the conductivity of the gate line is lower with the widening scheme of the preferred range. According to example 1 and example 4, it can be seen that, by adopting the scheme of example 4, which is preferably gradient and gradually widens the grid line, the requirement on the conductivity of the grid line is lower, thereby being more beneficial to mass production and lower in cost. It can be seen from examples 4, 5 and 6 that the use of the preferred gradient widening embodiment 5 scheme of the present invention requires less conductivity for the gate line. It can be seen from examples 1 and examples 7-9 that the preferred edge size approach of the present invention requires less conductivity for the gate lines while achieving good short circuit current and conductivity requirements, and battery conversion efficiency. It can be seen from the embodiments 1 and 10 that the scheme of the present invention, in which the width of the main gate of the two side regions is preferable, is more advantageous in terms of achieving excellent short-circuit current.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.

Claims

1. An electrode structure of a back contact battery, the electrode structure being disposed on a back surface of the back contact battery, the back surface being divided into a middle region and two side regions in an X-axis direction of a plane in which the back surface is disposed, the electrode structure comprising:

the first main grids and the second main grids are adjacent and arranged in pairs in the middle area, and the first grid lines and the second grid lines are alternately arranged between the first main grids and the second main grids;

2. The electrode structure of claim 1, wherein the electrode structure comprises a plurality of electrodes,

the curved extension comprises at least one of an L-shaped extension, a U-shaped extension, a V-shaped extension and a T-shaped extension;

and/or, the third main grid, the fourth main grid and the main grid arranged in the middle area are all horizontal to the edge lines of the two side areas in the Y-axis direction.

3. The electrode structure of claim 1, wherein the electrode structure comprises a plurality of electrodes,

at the first interval and/or the second interval, the third grid lines and the fourth grid lines which are alternately arranged are symmetrically distributed along the vertical central lines of the corresponding main grids in the two side areas;

and/or the widths of the third main gate and the fourth main gate are respectively 1-2 times of the widths of the main gates arranged in the middle area.

4. The electrode structure according to claim 1, wherein the shortest distance D in the X-axis direction of the first and second intervals is each independently 1 to 15 mm;

in the Y-axis direction, the shortest distance d between the end of the corresponding main grid in the first side region and the second side region and the side of the corresponding side region is 1-15 mm;

in the X-axis direction and/or the Y-axis direction, the shortest distance L between the outermost third grid line or fourth grid line and the edge or side edge of the corresponding side area in the two side areas is 0.01-1 mm; and D are both greater than L.

5. Electrode structure according to claim 1, characterized in that the lengths of the different third and/or fourth grid lines with the edge sections extending in a curved shape increase gradually and the widths widen gradually in the edge direction from the inside to the outside near the two side areas.

6. Electrode structure according to claim 5, characterized in that, in the different third and/or fourth gate lines with edge sections extending in a curved manner, the width of the respective gate line is increased by a factor of 1-4 compared to the width of the adjacent shorter gate line for every 1-fold increase in the length of the respective gate line.

7. The electrode structure according to claim 1, wherein a width of the third gate line having the edge section extending in a curved shape and a width of the fourth gate line having the edge section extending in a curved shape are each independently 1 to 6 times a width of the gate line provided in the intermediate region.

8. The electrode structure according to claim 1, wherein a plurality of side electrode units are disposed on the first side region and the second side region, the plurality of side electrode units are sequentially arranged in the Y-axis direction, and the side electrode units are unit structures including the third gate line, the fourth gate line, the third main gate and the third Pad point disposed thereon, and the fourth main gate and the fourth Pad point disposed thereon.

9. The electrode structure of claim 1, wherein the first and second gate lines have the same width, and the third and fourth gate lines have the same width.

10. The electrode structure of claim 1, wherein a distance between adjacent first and second gate lines is 0.1-0.6mm and a distance between adjacent third and fourth gate lines is 0.1-0.6mm.

11. The electrode structure of claim 1, wherein the sum of the total area occupied by the first and second, third and fourth gate lines on the back surface is 8% -30% of the back surface area, and the thicknesses of the first and second, third and fourth gate lines are each independently 5-10 μm.

12. The electrode structure of claim 1, wherein the first and second main gates are each horizontal to edge lines of both side regions in the Y-axis direction, a fourth gate line in the first side region is electrically connected to an adjacent second main gate and second Pad point, and a third gate line in the second side region is electrically connected to an adjacent first main gate and first Pad point; the first Pad point and the second Pad point respectively comprise a left Pad point and a right Pad point, and the left Pad point and the right Pad point are distributed in bilateral symmetry or oblique symmetry with the corresponding main grid as the center.

13. The electrode structure of claim 1, wherein the number of first main grids is the same as the number of second main grids, and the number of first main grids is 3-10; the number of the first Pad points on the first main gate is 10-100, and the number of the second Pad points on the second main gate is the same.

14. The electrode structure according to claim 1, wherein a plurality of intermediate electrode units are disposed in the intermediate region, and the plurality of intermediate electrode units are sequentially arranged along the X-axis direction and/or the Y-axis direction of the back surface, and the intermediate electrode units are unit structures including the first gate line, the second gate line, the first main gate and the first Pad points disposed thereon, and the second main gate and the second Pad points disposed thereon.

15. A back contact battery, characterized in that its back side arrangement comprises an electrode structure according to any of claims 1-14.