Battery assembly and photovoltaic system

Abstract

The invention is applicable to the field of photovoltaic technology, and provides a battery assembly and a photovoltaic system, each battery piece comprises a chamfered edge with a chamfer and a cut edge which is formed by cutting and is not chamfered, and the chamfered edge and the cut edge in the battery piece are opposite to each other. According to the technical scheme, the sizes, the material characteristics and the lamination widths of the different battery pieces and the comprehensive performance of the corresponding battery assembly are recorded and experimented, and the relation model of the upper limit of the lamination widths of the battery assembly is established, namely, the relation model of the upper limit of the lamination widths of the battery assembly is established. The upper limit of the width d of the overlapping area meets the following relational expression: d is less than or equal to (L1-L2) / 2 * tan theta + L1 / (L2 * a * sigma), the comprehensive performance of the battery assembly is optimal, and when the lamination width of different battery pieces is designed, the size and material characteristics of a target battery piece needing to be designed are substituted into a relational model, so that the design of the lamination width of the battery piece is completed. And the upper limit of the width of the battery piece lamination meeting the optimal comprehensive performance of the target battery assembly can be designed.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaic technology, and in particular relates to a battery assembly and a photovoltaic system. Background Art

[0002] Solar cells are devices that utilize solar energy and directly convert light energy into electrical energy through the photoelectric effect or the photochemical effect. Solar cells include sliced ​​solar cells. At present, the production of sliced ​​solar cells usually involves cutting the solar cells that have formed multiple film layers to cut the entire solar cell into at least two sliced ​​solar cells, such as two half slices. After that, the sliced ​​solar cells are used to make photovoltaic modules. Since the voltage output by a single cell is low, a certain number of cells are usually connected in series to form a battery string. Among them, the stacked module is widely used because it can eliminate the gap between cells, increase the light receiving area on the front of the photovoltaic module, and thus improve the photoelectric conversion efficiency of the photovoltaic module. The stacked module is to overlap multiple cells in sequence. When designing the stacking distance between cells, the size of the stacking distance needs to be reasonably designed. When the stacking distance is too small, the risk of hidden cracks is greater, affecting the yield of the battery module. When the stacking distance is too large, the area of ​​the battery that can receive light will be reduced, affecting the photoelectric conversion efficiency of the battery module. Based on the comprehensive performance considerations in the production of battery modules, it is necessary to select a reasonable stacking distance, which can ensure the efficiency of the battery module on the basis of less impact on the production yield of the battery module. The prior art lacks a design method for the stacking width between battery cells, resulting in the problem of low efficiency of current battery assemblies. Summary of the invention

[0003] The present invention provides a battery assembly, aiming to solve the problem that the prior art lacks a design method for the stacking width between battery sheets, resulting in low efficiency of the current battery assembly.

[0004] The present invention is implemented as follows: a battery assembly includes a plurality of battery cells, each of the battery cells includes a chamfered edge with a chamfer and a cut edge without a chamfer formed by cutting, the chamfered edge and the cut edge in the battery cell are opposite, and the plurality of battery cells are partially overlapped in sequence along a first direction to form a plurality of overlapping regions, the chamfered edge of one of two adjacent battery cells overlaps the cut edge of the other, and the width d of each overlapping region in the first direction satisfies the following relationship: d≤(L1-L2) / 2*tan θ + L1 / (L2*a*σ), wherein L1 is the length of the cut edge of the battery cell, in mm; L2 is the length of the chamfered edge of the battery cell, in mm; θ is the chamfer angle of the battery cell, in rad; a is the correction coefficient, and a is 0.05 mm -1 *Mpa -1; σ is the structural strength of the battery cell, in MPa; wherein the structural strength σ of the battery cell satisfies the following relationship: σ=b / (L1*h 2 ), where b is a constant and its value is 620 mm -1 *Mpa -1 ; L1 is the length of the cut edge of the battery cell, in mm; h is the thickness of the battery cell, in mm.

[0005] Optionally, the length of the chamfered edge is L1, the length of the cutting edge is L2, and the difference between L1 and L2 is greater than or equal to 1 mm and less than or equal to 10 mm.

[0006] Optionally, the length of L1 ranges from 150 mm to 250 mm.

[0007] Optionally, the length of L2 ranges from 140 mm to 240 mm. Optionally, the chamfer angle θ of the battery cell is in the range of greater than 0 and less than π / 2.

[0008] Optionally, the structural strength σ of the battery cell ranges from 20 to 300 MPa.

[0009] Optionally, the thickness of the battery cell ranges from 0.05 to 0.5 mm.

[0010] Optionally, the chamfered edges of the battery cells are stacked on the cut edges of adjacent battery cells.

[0011] Optionally, each of the plurality of overlapping regions has an equal width in the first direction.

[0012] In the technical solution of the present invention, the size, material properties, stacking width of different battery cells and the comprehensive performance of the corresponding battery assembly are recorded and experimented to establish a relationship model of the upper limit of the stacking width of the battery assembly, that is, the width d of the overlapping area satisfies the following relationship: d≤(L1-L2) / 2*tan θ + L1 / (L2*a*σ), the comprehensive performance of the battery assembly is optimal, after exceeding this upper limit, the efficiency of the battery assembly drops sharply, and the comprehensive performance of the assembly cannot meet the factory standard. Through the relationship design of the above-mentioned stacking width, when designing the stacking width of different battery cells, the size and material properties of the target battery cell to be designed are substituted into the relationship model, and the upper limit of the battery cell stacking width that meets the best comprehensive performance of the target battery assembly can be designed. At the same time, the overlapping width between the battery cells is designed according to the above-mentioned relationship type, which has the characteristics of fast design and high efficiency, and is helpful for product production decisions.

[0013] A photovoltaic system includes the above-mentioned battery assembly. The technical effect of the present invention is the same as the technical effect of the above-mentioned battery assembly, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the battery cell provided by the present invention; Figure 2 It is a structural schematic diagram of the first battery assembly provided by the present invention; Figure 3 It is a structural schematic diagram of the second battery assembly provided by the present invention; Figure 4 It is a schematic diagram of the structure of the third battery assembly provided by the present invention.

[0015] Description of reference numerals: 100, battery cell; 101, chamfered edge; 102, cutting edge; 200, overlapping area; 300, bevel edge; 400, side edge. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0017] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0018] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0019] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0021] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the examples of various specific processes and materials provided by the present invention, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0022] like Figure 1As shown, in an embodiment of the present invention, a battery assembly includes a plurality of battery cells 100, each battery cell 100 includes a chamfered edge 101 with chamfers and a cut edge 102 without chamfers formed by cutting. It should be noted that, in the embodiment of the present application, the battery cell 100 is usually formed by cutting a single crystal silicon rod in a square shape, and the single crystal silicon rod is generally cylindrical. In order to maximize the illumination area and save silicon rod materials, the battery cell 100 formed by cutting a single crystal silicon rod in a square shape usually has a right angle. In order to achieve the purpose of smoother corners of the battery cell 100 and reduce corner stress, it is usually necessary to chamfer the right angle so that the battery cell 100 has four chamfers. In addition, in order to make the battery cell 100 have different specifications and can be used in different environments, the battery cell 100 can be further cut and divided into multiple small-sized battery cells 100. Exemplarily, the battery cell 100 in the embodiment of the present application can be a half-cell cell obtained by slicing a whole battery cell, and the four corners of the whole battery cell are chamfered. The half-cell cell formed by slicing has a chamfered edge 101 on one side and a right-angled edge on the other side. The chamfered edge 101 is a non-cutting edge 102, and the right-angled edge is a cutting edge 102. The chamfered edge 101 of the half-cell cell is the chamfered edge 101 of the whole battery cell 100, and the right-angled edge of the half-cell cell 100 is the cutting edge 102 formed by cutting the whole battery cell 100 into pieces.

[0023] In some embodiments, the two sides of any battery cell 100 along the first direction are respectively a chamfered edge 101 and a cutting edge 102, and any battery cell also has two side edges 400 in the second direction, the chamfered edge 101 and the cutting edge 102 are opposite, and the two side edges 400 are opposite. Furthermore, the chamfered edge 101 of the battery cell 100 is a chamfered structure at both corners in the second direction, and the chamfered structure has a bevel 300, and the bevel 300 connects the adjacent side edges 400 and the chamfered edge 101. One side edge of the battery cell 100 has a chamfered structure along the second direction, and the side edge of the battery cell 100 is the chamfered edge 101; the other side edge of the battery cell 100 has a right-angle structure along the second direction, and the side edge of the battery cell 100 is the cutting edge 102.

[0024] In the embodiment of the present application, the second direction intersects with the first direction. Specifically, the second direction may be perpendicular to the first direction. Exemplarily, the first direction may be the width direction of the battery cell 100 , and the second direction may be the length direction of the battery cell 100 .

[0025] like Figure 2As shown, in some embodiments, the chamfered edge 101 and the cut edge 102 of the battery cell 100 are opposite, and multiple battery cells 100 are partially overlapped in sequence along the first direction to form multiple overlapping areas 200, and the chamfered edge 101 of one of two adjacent battery cells 100 overlaps the cut edge 102 of the other. Specifically, the battery assembly includes multiple battery cells, and the multiple battery cells can be connected in series to form a battery string, and the multiple battery strings can be connected in series or in parallel to form a battery assembly.

[0026] In the back-contact battery assembly, the contact area between the overlaps is not conductively connected, that is, there is no need to set conductive glue or other adhesive between the overlap areas 200, and the battery cells 100 are only overlapped together. Among them, the adjacent battery cells 100 in the battery string are connected in series through welding strips, and the overlapping areas 200 can be fixedly connected by the series-connected welding strips, wherein the series-connected welding strips are located on the back side of the battery cells 100. In this way, there is no gap between the battery cells 100 and the battery cells 100, so that the welding strips can be better hidden, and the overlapping arrangement between the battery cells 100 can reduce the size of the battery assembly, thereby making the battery string occupy a smaller space. In other words, when the size of the battery assembly is constant, more battery cells 100 can be placed to increase the power of the battery string and reduce the cost per watt.

[0027] In some embodiments, from the perspective of the light-receiving surface of the battery assembly, the stacking method of the battery cell 100 can be specifically selected as follows: the chamfered edge 101 of the second battery cell overlaps the cut edge 102 of the first battery cell, the chamfered edge 101 of the third battery cell overlaps the cut edge 102 of the second battery cell, and they are stacked in sequence until the last N-th battery cell, where N is a positive integer; or the cut edge 102 of the second battery cell overlaps the chamfered edge 101 of the first battery cell, the cut edge 102 of the third battery cell overlaps the chamfered edge 101 of the second battery cell, and they are stacked in sequence until the last N-th battery cell, where N is a positive integer, or the above two overlapping methods can also exist simultaneously in the battery assembly. It should be noted that since each battery cell 100 has a relatively set cut edge 102 and chamfered edge 101, the chamfered edges 101 and cut edges 102 of multiple battery cells 100 are overlapped, and the overlapping method of each two adjacent battery cells 100 is consistent, which is helpful for the layout of the battery assembly and simplifies the layout steps.

[0028] It should be noted that the setting of the stacking width of the battery cells 100 will affect the efficiency of the battery module. Specifically, the battery cells 100 are overlapped, which increases the proportion of the light-receiving area of ​​the stacking structure of the module in the same size of the module layout compared to the conventional spacing between the battery cells. However, on the other hand, the overlapping of the battery cells 100 will cause partial shading of the battery cells. The efficiency improvement brought about by the increase in the proportion of the light-receiving area of ​​the module and the efficiency loss of the module caused by partial shading of the battery cells need to be balanced through the reasonable design of the stacking width. In addition, the cutting edge 102 of the battery cell 100 overlaps with the chamfered edge 101 of the adjacent battery cell 100. Due to the uneven current distribution at the edge of the battery cell 100, when the overlapping width between the battery cells 100 reaches a certain limit point, the module efficiency will drop suddenly. This is also an influencing factor that needs to be considered when designing the stacking width.

[0029] Based on the overlapping manner of the above-mentioned two adjacent battery cells 100, and the comprehensive assessment of the above-mentioned various influencing factors, the inventors have established a design calculation model for the upper limit of the stacking width by fitting the functional relationship between the material properties and structural parameters of the battery cell 100 and the stacking width of the battery cell through numerical simulation and experimental testing. The width d of each overlapping area 200 in the first direction satisfies the following relationship: d≤(L1-L2) / 2*tan θ + L1 / (L2*a*σ), L1 is the length of the cut edge of the battery cell, in mm, L2 is the length of the chamfered edge of the battery cell, in mm, θ is the chamfer angle of the battery cell, in rad, and a is the correction coefficient, in 0.05 mm -1 *Mpa -1 , σ is the structural strength of the battery cell, in MPa. Among them, L1, L2, and θ of the battery cell in the formula determine the shape structure of the battery cell 100. The structural strength of the battery cell 100 is related to the material properties of the battery cell 100. During the battery assembly packaging process, since the thickness of the overlapping area of ​​the battery cell is twice the thickness of the non-overlapping area, mechanical stress concentration may occur. This stress will cause the battery cell 100 to have a risk of hidden cracks (micro cracks), which will lead to component failure. Therefore, when designing the stacking width, the material properties of the battery cell 100 need to be considered to further correct the upper limit of the stacking width, improve the risk of hidden cracks of the battery cell during the packaging process, and achieve long-term stability of the battery assembly.

[0030] Furthermore, in some embodiments, according to the thickness h of different battery cells 100, the length L1 of the cutting edge 102 and the corresponding structural strength σ, the functional relationship between the thickness of the battery cell 100, the length L1 of the cutting edge 102 and the structural strength σ is further fitted through numerical simulation and experimental testing. The structural strength σ of the battery cell 100 satisfies the following relationship: σ=b / (L1*h 2), b is a constant, and the value of b is 620mm -1 *Mpa -1 ; L1 is the length of the cut side of the cell, in mm; h is the thickness of the cell, in mm. In the embodiment of the present application, by fitting the experimental data of the structural strength test of the cell 100, the associated physical quantities and the constant value b of the structural strength of the cell 100 are obtained. That is to say, by substituting the length and thickness of the cell 100, which are physical quantities that can be measured intuitively, into the above formula, the structural strength of the cell 100 can be obtained, thereby avoiding the disadvantage that the material properties of the cell 100 cannot be directly obtained, and further expanding the scope of application of the design formula.

[0031] Furthermore, the fitting of the constant b value in the relationship formula of structural strength σ is explained below: In the embodiment of the present application, the structural strength of several battery cells is tested, and the structural strength calculation constant based on the single crystal silicon substrate back contact battery cell is fitted according to the four-point structural strength calculation formula.

[0032] The four-point structural strength test (Four-Point Bending Test) used in the embodiment of the present application is to measure the maximum resistance of the material under bending load by applying four loading points (two support points and two loading points) on the specimen. It is widely used to test the mechanical strength of photovoltaic modules (such as silicon wafers or glass substrates) because these materials are usually brittle and susceptible to local stress concentration. The test device includes two lower support points and two upper loading points to form an inner and outer span. The specimen is subjected to force under four-point loading, and the maximum bending stress occurs in the area between the two upper loading points. Compared with the conventional three-point structural test, the stress distribution of the four-point test is more uniform, avoiding the local stress concentration caused by single-point loading, and is therefore more suitable for evaluating the overall structural performance of the material. The calculation formula for structural strength is: σ =(3F x L) / (2b xh 2 ), where structural strength σ (unit: MPa or N / mm 2 ), F: maximum load (unit: N), i.e. the force when the specimen breaks, L: outer span (unit: mm), i.e. the distance between the two lower support points, specimen width (unit: mm), h: specimen thickness (unit: mm). The data obtained by the four-point structural strength test and the corresponding structural strength calculation constants are as follows: In this application, multiple groups of test data obtained from the four-point structural strength test are used to fit the calculation constant of the structural strength of the monocrystalline silicon cell, and then the calculation formula of the structural strength is refitted to obtain the formula σ=b / (L1*h 2), the structural strength of the battery cell can be quickly and easily obtained according to the structural dimensions of the battery cell, and the structural strength calculation constant is applicable to various common specifications of battery cells, and the error is within the range allowed by the production process.

[0033] Especially in some special usage scenarios, for example, after the battery cells 100 are packaged to form a battery assembly, since the battery cells 100 are filled with solidified adhesive film, and the adhesive film and the back panel glass are bonded together, multiple battery cells 100 form a whole. At this time, the battery cell 100 cannot be completely peeled out separately. At this time, based on the above-mentioned calculation formula for the structural strength of the battery cell, the structural strength of the battery cell 100 can be calculated through multiple physical quantities that can be measured by the battery cell 100, which provides a theoretical basis for experimental verification.

[0034] In other aspects, the overlapping battery cells 100 have a greater risk of hidden cracks during the packaging process of the battery assembly due to the need for a lamination process. Increasing the stacking distance of the battery cells in this process can improve the risk of hidden cracks in the battery cells during the packaging process, but an excessively large stacking distance of the battery cells 100 will cause a more serious power loss in the assembly. The efficiency of the assembly is very important in the evaluation of the comprehensive performance of the assembly, and the loss of assembly efficiency is unacceptable. The inventor's repeated research and verification shows that when the stacking distance reaches (L1-L2) / 2*tan θ + L1 / (L2*a*σ), the risk of hidden cracks in the battery cells during the assembly packaging process will no longer decrease if the stacking distance continues to increase, but the power loss will still gradually increase. Therefore, we believe that (L1-L2) / 2*tan θ + L1 / (L2*a*σ) is the upper limit of the stacking distance. After exceeding this upper limit, there is no benefit for either the risk of hidden cracks or the power loss.

[0035] In the technical solution of the present invention, the size, material properties, stacking width of different battery cells 100 and the comprehensive performance of the corresponding battery assembly are recorded and experimented to establish a relationship model of the upper limit of the stacking width of the battery assembly, that is, the width d of the overlapping area 200 satisfies the following relationship: d≤(L1-L2) / 2*tan θ + L1 / (L2*a*σ), the comprehensive performance of the battery assembly is optimal, after exceeding this upper limit, the efficiency of the battery assembly drops sharply, and the comprehensive performance of the assembly cannot meet the factory standard. Through the above-mentioned stacking width relationship design, when designing the stacking width of different battery cells 100, the size and material properties of the target battery cell 100 to be designed are substituted into the relationship model, and the upper limit of the stacking width of the battery cell 100 that meets the best comprehensive performance of the target battery assembly can be designed. At the same time, the overlapping width between the battery cells 100 is designed according to the above-mentioned relationship, which has the characteristics of fast design and high efficiency.

[0036] Understandably, in the embodiments of the present application, since there is partial overlap between the battery cells 100 in the battery module, it can be understood that the width d of the overlap region in the first direction is at least greater than 0. That is to say, the distance of the width d of the overlap region in the first direction is: 0 < d ≤ (L1 - L2) / 2 * tan θ + L1 / (L2 * a * σ). Thus, the overlap distance between the battery cells can be selected within the above range, which helps to make quick decisions during the product layout design process and can ensure that the comprehensive performance of the battery module meets the factory standards.

[0037] It should be noted that based on the relationship between the range of the lamination distance of the battery cells designed above and the light conversion efficiency of the battery module, within the range where the d value is greater than 0 and less than or equal to (L1 - L2) / 2 * tan θ + L1 / (L2 * a * σ), due to the prominent efficiency loss of the module caused by the partial occlusion of the battery cells 100, and the limited efficiency improvement brought by the increased proportion of the light-receiving area of the module where the battery cells overlap, overall, the actual efficiency of the battery module shows a gradually decreasing trend. However, during this process, due to the increase in the lamination distance, the risk of hidden cracks in the module decreases, which is reflected in the gradually increasing trend of the yield rate of the module. For the evaluation of the two influencing factors, exemplarily, in the embodiments of the present application, the following evaluation model formula is adopted: (0.1 * yield rate + 0.9 * efficiency) * 280 to evaluate the comprehensive performance of the module, so as to obtain the optimal lamination distance scheme in the embodiments of the present application. Of course, in other embodiments, based on different user requirements, different production processes, and differences in the usage environment of the product, the weighting coefficients of the above evaluation model for the comprehensive performance of the module can also be adjusted otherwise, and the present application does not limit this.

[0038] Exemplarily, the following gives a set of data for illustration. Through our lamination formula, the reasonable lamination range is calculated to be between 0 and 1.14 mm. The specific parameters of the battery cells are as follows in the table: Verified by our actual production measurement data, the comprehensive scores of the lamination distance of the module within this range for the module efficiency and the module yield rate are shown in the following table (viewed from the perspective of the light-receiving surface of the battery module, the chamfered edges of the battery cells are laminated on the cutting edges of adjacent battery cells): The final test results show that within the upper limit range of the designed lamination distance, the comprehensive performance scores of the battery modules with the first five groups of lamination distances are all higher than 80, indicating that the modules designed according to the five groups of lamination distances all have the characteristics of high performance. When the lamination distance exceeds the designed upper limit, the efficiency of the module drops sharply, so the comprehensive performance of the module cannot meet the production requirements.

[0039] Such as Figure 3 and Figure 4As shown, in other embodiments, the chamfered edge 101 of one of two adjacent battery cells 100 may overlap with the chamfered edge 101 of the other, and the cut edge 102 of one of two adjacent battery cells 100 may overlap with the cut edge 102 of the other. In this way, there are two types of overlapping methods of two adjacent battery cells 100. In these two types of overlapping methods, the upper limit of the width of the overlapping area 200 can also be applied to the following relationship: d≤(L1-L2) / 2*tan θ +L1 / (L2*a*σ), which is convenient for the layout design of the battery assembly.

[0040] In some embodiments, the chamfered edge 101 of the cell 100 and the cut edge 102 of the adjacent cell 100 are parallel to each other, and the distances between the edges of the plurality of cells 100 are equal. In another embodiment, the chamfered edge 101 of the cell 100 may also be arranged non-parallel to the cut edge 102 of the adjacent cell 100, that is, the chamfered edge 101 of the cell 100 may also be slightly deflected relative to the cut edge 102 of the adjacent cell 100, in which case the width d of the overlap region 200 is the average stack width between the two adjacent cells 100.

[0041] Furthermore, in the embodiment of the present application, the chamfered edge 101 of the battery cell 100 is stacked on the cut edge 102 of the adjacent battery cell 100. In this way, there is no suspended area below the chamfered edge 101 of the battery cell 100, and the cut edge 102 of the battery cell 100 can effectively support the chamfered edge 101 of the adjacent battery cell 100. The corners of the battery cell 100 are not easy to crack during the lamination process of the battery assembly, further reducing the risk of hidden cracks in the battery assembly.

[0042] In some embodiments, the length of the chamfered edge 101 is L1, the length of the cutting edge 102 is L2, and the difference between L1 and L2 is greater than or equal to 1 mm and less than or equal to 10 mm. In such an embodiment, the difference between the length L1 of the chamfered edge 101 and the length L2 of the cutting edge 102 can range from 1 mm, 2 mm, 3 mm, 5 mm, 7 mm, 8 mm, 9 mm, 10 mm, or any value between 1 mm and 10 mm, and is not specifically limited here.

[0043] In some embodiments, the length of L1 ranges from 150 mm to 250 mm. In such embodiments, the length of L1 can be 150 mm, 180 mm, 190 mm, 200 mm, 220 mm, 230 mm, 240 mm, 250 mm or any value between 180 mm and 250 mm, without limitation herein.

[0044] In some embodiments, the length of L2 ranges from 140 mm to 240 mm. In such embodiments, the length of L2 can be 140 mm, 160 mm, 170 mm, 180 mm, 190 mm, 200 mm, 240 mm, or any value between 140 mm and 240 mm, without limitation.

[0045] In some embodiments, the chamfer angle θ of the battery cell 100 is greater than 0 and less than π / 2. Further, the chamfer angle θ of the battery cell 100 is in the range of 0.1 to 1.5, in rad. In such an embodiment, the chamfer angle θ of the battery cell 100 can be 0.1, 0.2, 0.5, 0.7, 0.8, 1, 1.1, 1.2, 1.3, 1.4, 1.5 or any value between 0.1 and 1.5, and is not limited to this. Figure 1 As shown, the chamfer angle θ mentioned in the embodiment of the present application is the angle formed by the hypotenuse of the chamfer structure relative to the parallel line of the cutting edge.

[0046] In some embodiments, the structural strength σ of the battery cell 100 ranges from 20 to 300 MPa. In such an embodiment, the structural strength σ of the battery cell 100 may be 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, 200 MPa, 300 MPa or any value between 20 MPa and 300 MPa, and is not specifically limited herein.

[0047] In some embodiments, the thickness of the battery cell 100 ranges from 0.05 to 0.5 mm. In such embodiments, the thickness h of the battery cell 100 can be 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, or any value between 0.05 mm and 0.5 mm, and is not limited to this.

[0048] In some embodiments, each of the multiple overlapping regions has an equal width in the first direction. The consistent overlapping width can reduce the resistance difference between different overlapping regions, make the current distribution more uniform, avoid the generation of local hot spots, and thus improve the overall component efficiency. In addition, the uniform overlapping width can reduce processing complexity, improve production consistency, reduce assembly errors caused by overlapping size deviations, reduce scrap rate, and save costs.

[0049] In other embodiments, the width of the multiple overlapping regions 200 may change in a gradient pattern in the first direction. For example, the multiple overlapping regions 200 include the nth overlapping region and the n+1th overlapping region arranged along the first direction, and the width of the nth overlapping region is greater than the width of the n+1th overlapping region, wherein n≥1, n is a positive integer. Of course, it can be understood that the width of the lamination region that changes in a gradient pattern is also within the upper limit of the design, and the gradient change of the overlapping width can disperse the mechanical stress. For example, a wider overlap is designed in the stress concentration area (such as the edge of the component) to enhance the fatigue resistance. In a vibration or impact environment, the gradient design can absorb energy and transmit it step by step to reduce the risk of hidden cracks. Alternatively, at least one of the widths of the multiple overlapping areas 200 is the first distance, and the widths of the remaining overlapping areas 200 are the second distance, and the first distance is greater than the second distance. This differentiated design of the overlapping areas 200 is particularly suitable for layout designs that have special requirements for the overlapping distance of battery cells near the end of the battery string. For example, for some layout battery components, multiple battery cells are connected in sequence to form a battery string, and the width of the overlapping area formed by the battery cell closest to the end of the battery string and its adjacent battery cell is the first distance, and the overlapping distance between the remaining battery cells is the second distance, and the first distance is greater than the second distance. This can solve the problem of excessive offset in the lamination process of battery cells at the end of the battery string.

[0050] In some embodiments, a photovoltaic system includes a battery assembly. In this embodiment, the photovoltaic system can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water surface power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple battery assemblies. For example, multiple battery assemblies can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid, and then connected to the mains network to realize solar power supply.

[0051] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0052] The above description is only a 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 scope of the present invention.

Claims

1. A battery assembly, characterized in that: The invention comprises a plurality of battery cells, each of which comprises a chamfered edge with a chamfer and a cut edge without a chamfer formed by cutting, wherein the chamfered edge and the cut edge in the battery cell are opposite to each other, and the plurality of battery cells are partially overlapped in sequence along a first direction to form a plurality of overlapping regions, wherein the chamfered edge of one of two adjacent battery cells overlaps the cut edge of the other, and the width d of each overlapping region in the first direction satisfies the following relationship: d≤(L1-L2) / 2*tan θ + L1 / (L2*a*σ), wherein L1 is the length of the cut edge of the battery cell, in mm; L2 is the length of the chamfered edge of the battery cell, in mm; θ is the chamfer angle of the battery cell, in rad; a is the correction coefficient, and a is 0.05 mm -1 *Mpa -1 ; σ is the structural strength of the battery cell, in MPa; wherein the structural strength σ of the battery cell satisfies the following relationship: σ=b / (L1*h 2 ), where b is a constant and its value is 620 mm -1 *Mpa -1 ; L1 is the length of the cut edge of the battery cell, in mm; h is the thickness of the battery cell, in mm.

2. The battery assembly according to claim 1, characterized in that The length of the chamfered edge is L1, the length of the cutting edge is L2, and the difference between L1 and L2 is greater than or equal to 1 mm and less than or equal to 10 mm.

3. The battery assembly according to claim 1, characterized in that The length of L1 ranges from 150 mm to 250 mm.

4. The battery assembly according to claim 1, wherein: The length of L2 ranges from 140 mm to 240 mm.

5. The battery assembly according to claim 1, characterized in that: The chamfer angle θ of the battery cell is in the range of greater than 0 and less than π / 2.

6. The battery assembly according to claim 1, characterized in that: The structural strength σ of the battery cell ranges from 20 to 300 MPa.

7. The battery assembly according to claim 1, characterized in that: The thickness of the battery cell ranges from 0.05 to 0.5 mm.

8. The battery assembly according to claim 1, wherein: The chamfered edges of the battery cells are stacked on the cut edges of the adjacent battery cells.

9. The battery assembly according to claim 1, wherein: Each of the plurality of overlapping regions has an equal width in the first direction.

10. A photovoltaic system, characterized in that: A battery assembly comprising any one of claims 1 to 9.

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