CN222601056U - Thermal composite battery - Google Patents

Abstract

The present application discloses a thermal composite battery cell, including N negative electrode sheets, M positive electrode sheets and a separator, M positive electrode sheets, N-M=1; a negative electrode ear is provided on the negative electrode sheet, a positive electrode ear is provided on the positive electrode sheet, and the separator includes a plurality of main bodies and a plurality of bending parts arranged alternately and continuously, wherein, along the thickness direction of the negative electrode sheet, the negative electrode sheet and the positive electrode sheet are alternately stacked, the adjacent negative electrode sheet and the positive electrode sheet are separated by the main body, the bending part is provided with an incompletely cut structure, the separator is folded along the incompletely cut structure, and at least part of the structure of the negative electrode ear and the positive electrode ear is located outside the separator; wherein, the two negative electrode sheets located on the outermost side are single-sided electrode sheets, and the other negative electrode sheets are double-sided electrode sheets. The present application overcomes the problem of poor alignment of existing thermal composite batteries, and has the advantages of good alignment and stable performance.

Description

Thermal composite battery core

Technical Field

The application belongs to the technical field of batteries, and particularly relates to a thermal composite battery cell.

Background

At present, the battery cell of the battery is mainly manufactured through a folding or winding process, and the laminated battery cell has various advantages and is widely applied. The pole pieces of the laminated battery core are in a free falling state in the folding process, the negative pole pieces and the positive pole pieces in the laminated battery core are dislocated, and the alignment degree of the laminated battery core is poor. In the battery charging process, lithium ions are released from the positive electrode plate and are inserted into the negative electrode plate, and as the positive electrode plate and the negative electrode plate are misplaced, the lithium ions cannot be completely inserted into the negative electrode plate, and the lithium ions which cannot be inserted into the negative electrode plate can only obtain electrons on the surface of the negative electrode plate, so that white metal lithium simple substance is formed, and lithium precipitation occurs. The cycle life of the battery is greatly shortened by lithium precipitation, the quick charge capacity of the battery is limited, the conditions such as combustion explosion and the like can be possibly caused, potential safety hazards exist, and the performance of the battery is reduced.

In the related art, in order to improve the alignment degree of the laminated battery cells, a shaping process is added in the production process of the laminated battery cells. After the thermal composite unit is folded to form the battery core in a free falling way, the battery core is clamped from two sides of the battery core by using a shaping cylinder, and all pole pieces in the battery core are aligned. Depending on the shaping cylinder to carry out electric core shaping, still there is the not good problem of alignment degree of electric core, has the pole piece in the shaping cylinder plastic in-process moreover to be clapped the circumstances of powder, increases the risk of core package short circuit.

Disclosure of utility model

The embodiment of the application provides a laminated battery cell, wherein an incomplete cutting structure is arranged on a bending part of a diaphragm, and the diaphragm is folded along the incomplete cutting structure, so that the laminated battery cell has the technical effects of good folding quality, high folding efficiency and good alignment.

In a first aspect, an embodiment of the present application provides a thermal composite cell, including:

N negative pole pieces, N is a positive integer greater than 1, and a negative pole tab is arranged on the negative pole pieces;

m positive plates, M is a positive integer greater than 1, N-M=1, and positive lugs are arranged on the positive plates;

The separator comprises a plurality of main body parts and a plurality of bending parts which are alternately and continuously arranged, wherein the negative electrode plates and the positive electrode plates are alternately stacked along the thickness direction of the negative electrode plates, the adjacent negative electrode plates and positive electrode plates are separated by the main body parts, the bending parts are provided with incomplete cutting structures, the separator is folded along the incomplete cutting structures, and at least partial structures of the negative electrode lugs and the positive electrode lugs are positioned on the outer sides of the separator;

The two negative electrode plates positioned at the outermost side are the single-sided electrode plates, and the other negative electrode plates are the double-sided electrode plates.

Optionally, the single-sided pole piece comprises a negative electrode current collector and a negative electrode active layer, and the negative electrode current collector is close to one side surface of the main body part and is provided with the negative electrode active layer;

And/or, the double-sided pole piece comprises a negative electrode current collector and a negative electrode active layer, and the negative electrode active layer is arranged on two side surfaces of the negative electrode current collector.

Optionally, the membrane includes a first membrane and a second membrane, the first membrane includes a first main body portion and a first bending portion, the second membrane includes a second main body portion and a second bending portion, and the first bending portion and/or the second bending portion is provided with the incomplete cutting structure.

Optionally, the first bending portion and the second bending portion are both provided with the incomplete cutting structure, and a projection of the incomplete cutting structure on the first bending portion on the second diaphragm overlaps with the incomplete cutting structure on the second bending portion.

Optionally, the incomplete cutting structure includes a plurality of through holes penetrating through the diaphragm, and the plurality of through holes are arranged at intervals along the width direction of the diaphragm.

Optionally, the intervals between adjacent through holes are the same.

Optionally, the through hole is circular or rectangular in shape.

Optionally, along the width direction of the diaphragm, the interval between adjacent through holes is S1, wherein S1 is more than or equal to 5mm and less than or equal to 20mm.

Optionally, the through hole has a first dimension L1 and a second dimension W1, where the first dimension is a distance between two parallel planes virtually abutting against the walls of the two sides of the through hole, and the second dimension is a distance between two parallel planes virtually abutting against the walls of the two ends of the through hole, where L1 is less than or equal to 1mm and less than or equal to 20mm, and/or W1 is less than or equal to 1mm and less than or equal to 2mm.

Optionally, the long side dimension of the negative electrode plate is larger than the long side dimension of the positive electrode plate, and the wide side dimension of the negative electrode plate is larger than the wide side dimension of the positive electrode plate.

Optionally, the distance between the long side of the positive plate and the long side of the negative plate is S2, and S2 is more than or equal to 1mm and less than or equal to 3mm;

And/or the distance between the broadside of the positive plate and the broadside of the negative plate is S3, and S3 is more than or equal to 1mm and less than or equal to 3mm.

Optionally, the long side dimension of the main body part is larger than the long side dimension of the negative plate, and the wide side dimension of the main body part is larger than the wide side dimension of the negative plate.

Optionally, the distance between the long side of the negative plate and the long side of the diaphragm is S4, wherein S4 is more than or equal to 2mm and less than or equal to 4mm;

And/or the separator continuously comprises a starting end, wherein the distance between the starting end and the wide edge of the negative electrode sheet close to the starting end is S5, and S5 is more than or equal to 1mm and less than or equal to 3mm.

Optionally, the thickness of the negative electrode current collector is D1, D1 is more than or equal to 4 mu m and less than or equal to 6 mu m;

and/or, the thickness of the negative electrode active layer is D2, and D2 is more than or equal to 50 mu m and less than or equal to 200 mu m.

Optionally, the positive plate includes a positive current collector and a positive active layer, and both sides of the positive current collector are provided with the positive active layer.

Optionally, the negative plate, the positive plate and the diaphragm are in thermal composite connection.

Optionally, along the thickness direction of the negative electrode sheet, all projections of the negative electrode tabs overlap, and/or all projections of the positive electrode tabs overlap.

Optionally, the projection of the negative electrode tab and the positive electrode tab in the plane of the main body portion is arranged side by side.

According to the thermal composite battery cell provided by the embodiment of the application, the thermal composite battery cell comprises N negative plates, M positive plates and a diaphragm, wherein the number of the negative plates is one more than that of the positive plates, the diaphragm comprises the main body part and the bending parts, the adjacent main body parts are connected through the bending parts, each bending part is provided with an incomplete cutting structure, the negative plates and the positive plates are alternately stacked along the thickness direction of the negative plates, each positive plate is positioned between the two negative plates, the adjacent negative plates and the positive plates are separated through the main body part, the occurrence of short circuit caused by direct contact of the negative plates and the positive plates is avoided, the diaphragm is not completely cut, continuous folding can be carried out along the straight line where the incomplete cutting part is located, each time is carried out along the straight line where the incomplete cutting part is located, the folding position is fixed, the alignment degree of the positive plates and the negative plates in the folded battery cell is guaranteed, the two negative plates at the outermost side are single-sided plates, the other negative plates are double-sided plates, the outer side surfaces of the outermost negative plates do not need to be covered with films, the material investment is reduced, the problem of the current thermal-cycle alignment degree of the battery cell is well, the electrical property is improved, the charge capacity is short, and the electrical property of the battery cell is well, and the battery cell has the safety is good, and the charging performance is compared.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings that are required to be used in the description of the embodiments will be briefly described below. It is evident that the figures in the following description are only some embodiments of the application, from which other figures can be obtained without inventive effort for a person skilled in the art.

For a more complete understanding of the present application and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings. Wherein like reference numerals refer to like parts throughout the following description.

Fig. 1 is a perspective view of a thermal composite cell according to an embodiment of the present application.

Fig. 2 is a top view of a thermal composite cell according to an embodiment of the present application.

Fig. 3 is a cross-sectional view of a first version of A-A of fig. 2.

Fig. 4 is a partial enlarged view at a in fig. 3.

Fig. 5 is a cross-sectional view of a second version of A-A of fig. 2.

Fig. 6 is a partial enlarged view at B in fig. 5.

Fig. 7 is a schematic diagram of a thermal composite cell according to an embodiment of the present application.

Fig. 8 is a schematic diagram of a composite laminate layer in one form in the method for manufacturing a thermal composite cell according to an embodiment of the present application.

Fig. 9 is a schematic diagram of another form of composite laminate in a method for manufacturing a thermal composite cell according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to fall within the scope of the application.

The thermal composite battery cell according to the embodiment of the application will be described in detail below with reference to the accompanying drawings.

Referring to fig. 1, 2, 3 and 4, fig. 1 is a perspective view of a thermal composite battery cell according to an embodiment of the present application, fig. 2 is a top view of the thermal composite battery cell according to the embodiment of the present application, fig. 3 is a cross-sectional view of a first form A-A in fig. 2, and fig. 4 is a partial enlarged view at a in fig. 3, where the embodiment of the present application provides a thermal composite battery cell including N negative electrode sheets 100, M positive electrode sheets 200 and a separator 300. The battery cell can be used as an energy storage unit of a battery, and the battery can convert the energy stored in the battery cell into current and supply the current to electronic equipment for use.

In this embodiment, referring to fig. 1, the negative electrode sheet 100 and the positive electrode sheet 200 are formed by cutting a negative electrode roll and a positive electrode roll, the shapes of the negative electrode sheet 100 and the positive electrode sheet 200 are rectangular, the negative electrode sheet 100 is provided with a negative electrode tab 130, the positive electrode sheet 200 is provided with a positive electrode tab 210, and the negative electrode tab 130 and the positive electrode tab 210 extend out of the diaphragm 300. The positive tab 210 and the negative tab 130 may each be at least partially located outside the separator 300.

In this embodiment, N negative electrode plates 100 and M positive electrode plates 200 are set, the values of N and M are positive integers greater than 1, N-m=1, and the number of N and M is specifically a plurality of energy storage designs according to the folded battery cells, but the number of negative electrode plates 100 is always one more than the number of positive electrode plates.

In this embodiment, referring to fig. 1, the separator 300 is a continuous film material, the separator 300 includes a plurality of main portions 310 and a plurality of bending portions 320 that are alternately and continuously arranged, the plurality of main portions 310 are stacked along the thickness direction X of the negative electrode sheet 100, adjacent main portions 310 are connected by the bending portions 320, the bending portions 320 are provided with incomplete cutting structures 330, and the separator 300 is bent at the incomplete cutting structures 330. For example, the separator 300 may be made of polypropylene, polyethylene terephthalate, polybutylene terephthalate, ethylene-propylene copolymer, cellulose, or the like.

In some embodiments, referring to fig. 3 and 4, the negative electrode tabs 100 and the positive electrode tabs 200 are alternately stacked in the thickness direction X of the negative electrode tabs 100, each positive electrode tab 200 is positioned between two negative electrode tabs 100, and adjacent negative electrode tabs 100 and positive electrode tabs 200 are separated by a main body portion 310. The two negative electrode plates 100 positioned at the outermost side are single-sided electrode plates B, and the other negative electrode plates 100 are double-sided electrode plates 100A. The projections of the positive electrode sheet 200 and the negative electrode sheet 100 in the thickness direction of the negative electrode sheet 100 fall entirely within the planar area of the body portion 310 therebetween, so that the body portion 310 can completely separate the negative electrode sheet 100 and the positive electrode sheet 200, preventing the positive electrode sheet 200 from being in contact with the negative electrode sheet 100 to cause a short circuit. The planar area of the body 310 is a continuous planar area surrounded by the outer contour of the body 310 projected in the thickness direction of the negative electrode sheet 100.

It can be appreciated that, before folding, the separator 300 is in a continuous band-shaped structure, the negative electrode sheet 100 and the positive electrode sheet 200 are combined on the main body 310 of the separator 300 to form a combined laminate, the separator 300 is provided with an incompletely cut structure 330, the distances between the negative electrode sheets 100 on the sides of the incompletely cut structure 330 are the same or substantially the same, and the combined laminate is folded along the straight line on which the incompletely cut structure 330 is located. The folding position is fixed, so that the alignment degree in the folding process is improved, the situation that lithium is separated out to pierce the diaphragm 300 due to the dislocation of the negative electrode plate 100 and the positive electrode plate 200 is avoided, and the electrical performance of the folding battery cell is improved. The outermost negative electrode plate 100 is set to be a single-sided electrode plate 100B, and an active material layer is not required to be arranged on the outermost side of the single-sided electrode plate 100B, so that material investment is reduced, and cost is lowered.

In some embodiments, the negative electrode sheet 100, the positive electrode sheet 200, and the separator 300 are thermally compositely connected. The negative electrode sheet 100 and the positive electrode sheet 200 are thermally compounded on the separator 300, that is, the negative electrode sheet 100 and the positive electrode sheet 200 are fixed on the surface of the separator 300 through a thermal compounding process. The thermal compounding process includes feeding positive electrode material roll, negative electrode material roll and diaphragm simultaneously, cutting the positive electrode sheet 200 and the negative electrode sheet 100 into single electrode sheets with required sizes by a cutter before entering a heating device, enabling the combination of the positive electrode sheet 200, the negative electrode sheet 100 and the diaphragm 300 to enter a heating system under the action of a roller, enabling the diaphragm 300 to be a glue-coated diaphragm, enabling the diaphragm to be sticky after being heated, enabling the baked positive electrode sheet 200, the baked negative electrode sheet 100 and the diaphragm 300 to be thermally compounded, and then rolling and cutting to form a composite lamination.

In some embodiments, referring to fig. 1 and 2, along the thickness direction X of the negative electrode sheet 100, the projections of all the negative electrode tabs 130 overlap, and the projections of all the positive electrode tabs 210 overlap. The negative electrode lugs 130 are arranged along with the negative electrode plate 100 in a stacked mode, the positive electrode lugs 210 are arranged along with the positive electrode plate 200 in a stacked mode, the thickness of one main body part 310 is arranged between adjacent negative electrode lugs 130 at intervals, the projections of all the negative electrode lugs 130 are arranged on the same position, the thickness of one main body part 310 is arranged between adjacent positive electrode lugs 210 at intervals, the projections of all the positive electrode lugs 210 are arranged on the same position, welding of all the negative electrode lugs 130 is integrated conveniently, all the positive electrode lugs 210 are integrated in a welded mode, and the occupied space of the negative electrode lugs 130 and the positive electrode lugs 210 is small.

In some embodiments, referring to fig. 1 and 2, the projections of the negative tab 130 of the negative electrode tab 100 and the positive tab 210 of the positive electrode tab 200 in the plane of the main body 310 are arranged side by side. The two sides of the main body 310 are respectively provided with the negative electrode plate 100 and the positive electrode plate 200, and the projection interval between the negative electrode tab 130 on the negative electrode plate 100 and the positive electrode tab 210 on the positive electrode plate 200 in the plane of the main body 310 is used for preventing the negative electrode tab 130 from interfering with the positive electrode tab 210, so that the electrical safety is ensured.

In some embodiments, referring to fig. 4, the double-sided pole piece 100A includes a negative electrode current collector 110 and a negative electrode active layer 120, and both sides of the negative electrode current collector 110 are provided with the negative electrode active layer 120.

In some embodiments, the single-sided pole piece 100B includes a negative current collector 110 and a negative active layer 120, and a side of the negative current collector 110 is provided with the negative active layer 120. Illustratively, the negative electrode current collector 110 may be copper, and the negative electrode active layer 120 may be graphite.

In this embodiment, referring to fig. 4, along the thickness direction X of the negative electrode sheet 100, the 1 st negative electrode sheet 100 and the 2 nd negative electrode sheet 100 are sequentially arranged from bottom to top, the 1 st negative electrode sheet 100 and the N th negative electrode sheet 100 are positioned at the outermost side of the thermal composite battery cell, the 1 st negative electrode sheet 100 and the N th negative electrode sheet 100 adopt single-sided electrode sheets 100B, the other negative electrode sheets 100 adopt double-sided electrode sheets 100A, and the negative electrode active layers 120 are disposed on the sides of the negative electrode current collectors 110 of the 1 st negative electrode sheet 100 and the N th negative electrode sheet 100, which are close to the main body portion 310.

The negative electrode plate 100 at the outermost side of the thermal composite battery cell is provided with the single-sided electrode plate 100B, so that the use of negative electrode active materials is reduced, the processing cost is reduced, the diaphragm 300 is not required to be coated at the outermost side of the single-sided electrode plate 100B, the diaphragm materials are reduced, the processing cost is further reduced, and compared with the related art, the two-layer negative electrode active layer 120 and the two-layer diaphragm 300 are reduced, and the thickness of the thermal composite battery cell is reduced.

In some embodiments, the number of the separators 300 may be plural, and the plurality of separators 300 may be stacked in the thickness direction of the negative electrode sheet 100. The cell may include a double layer separator, or may include more layers of separators, for example. The embodiments of the present application are described with reference to a double-layer diaphragm, and other embodiments of the double-layer diaphragm may be adaptively designed according to the embodiments of the double-layer diaphragm.

In some embodiments, referring to fig. 3 and 4, the separator 300 includes a first separator 340 and a second separator 350, and the first separator 340 and the second separator 350 are folded in a zigzag shape to form a separator including a main body portion 310 and a bent portion 320, and the negative electrode sheets 100 and the positive electrode sheets 200 are alternately stacked in a thickness direction X of the negative electrode sheets 100, with adjacent positive electrode sheets 200 and negative electrode sheets 100 being separated by the main body portion 310. The bent portion 320 of the first diaphragm 340 is provided with an incompletely cut structure 330 and/or the bent portion 320 of the second diaphragm 350 is provided with an incompletely cut structure 330. Specifically, the case includes that all the incompletely cut structures 330 are all disposed on the first membrane 340, or all the incompletely cut structures 330 are all disposed on the second membrane 350, or one part of the incompletely cut structures 330 are disposed on the first membrane 340 and the other part of the incompletely cut structures 330 are disposed on the second membrane 350, or the incompletely cut structures 330 are disposed on both the first membrane 340 and the second membrane 350, and the number and positions of the incompletely cut structures 330 on the first membrane 340 and the second membrane 350 are the same.

For example, referring to fig. 4, the battery cell may include a double-layer separator 300, i.e., a first separator 340 and a second separator 350. The first diaphragm 340 includes a first body portion 311 and a first bent portion 321, and the second diaphragm 350 includes a second body portion 312 and a second bent portion 322. The negative electrode sheet 100 is arranged between any two adjacent first body parts 311 and second body parts 312, and the positive electrode sheet 200 is arranged between any two adjacent first body parts 311 and between any two adjacent second body parts 312. The first membrane 340 and the second membrane 350 are each provided with an incompletely cut structure 330. The projection of the non-cut structure 330 on the first membrane 340 onto the second membrane 350 overlaps the continuous planar area enclosed by the outer contour of the non-cut structure 330 on the second membrane 350. When the membrane 300 is folded, the first membrane 340 and the second membrane 350 are folded along the same straight line, so that the alignment of the main body parts 310 of all layers in the folded battery cell is ensured, and the alignment degree of the laminated battery cell is improved.

For example, referring to fig. 4, the first bending portion 321 and the second bending portion 322 may be in a fitting connection, so long as a part of the structure of one bending portion contacts with the other bending portion, the two bending portions may be considered to be in a fitting connection. In other embodiments, the first bending portion 321 and the second bending portion 322 may not be in contact, which is not limited in the embodiment of the present application.

Referring to fig. 3, 4 and 8, before the separator 300 is folded, the first separator 340 and the second separator 350 are each in a continuous band structure, the positive electrode sheet 200 is combined between the first separator 340 and the second separator 350, and the single-sided sheet 100B is combined on the side of the first separator 340 facing away from the positive electrode sheet 200 and the side of the second separator 350 facing away from the positive electrode sheet 200 to form a composite stack. The incompletely cut structure 330 is located between the adjacent negative electrode sheets 100, the sides of the incompletely cut structure 330 are the same distance from the negative electrode sheet 100 on the side where they are located, and the separator 300 (i.e., the first separator 340 and the second separator 350) is folded at the incompletely cut structure 330. The incompletely cut structure 330 can release stress generated by folding, so that the diaphragm 300 is easy to fold when the incompletely cut structure 330 is in a folded position, thereby playing a role in limiting the folding position and improving the folding quality and the folding efficiency.

According to the embodiment of the application, the folding position of the diaphragm 300 is limited by arranging the incomplete cutting structure, so that the diaphragm 300 can be basically folded at the same position, the alignment degree of the negative electrode plate 100 and the positive electrode plate 200 in the folded battery cell is ensured, the situation that lithium is separated out to puncture the diaphragm 300 due to the dislocation of the negative electrode plate 100 and the positive electrode plate 200 is avoided, and the service life, the quick charge capacity, the safety and other electrical properties of the folded battery cell are improved.

In some embodiments, referring to fig. 1 and 7, the incompletely cut structure 330 includes a plurality of through holes 331 penetrating the diaphragm 300, and the plurality of through holes 331 are spaced apart along the width direction of the diaphragm 300. Or a plurality of through holes 331 are arranged in an array, and a plurality of through holes 331 are arranged in a row along the length direction Y of the diaphragm 300. Each row of the through holes 331 may be aligned in the width direction Z of the diaphragm 300. For example, the arrangement directions of the plurality of columns of the through holes 331 may be parallel to each other. In other embodiments, there may be an included angle between the arrangement direction of at least one row of through holes 331 and the arrangement direction of other rows of through holes. Illustratively, the included angle may be less than or equal to 10 °, e.g., 1 °,2 °,5 °, etc. In other embodiments, the included angle may be greater than 10 °, and embodiments of the present application are not limited in this respect. For example, the plurality of through holes 331 of one of the two arbitrary columns of through holes 331 may be disposed one-to-one opposite to the plurality of through holes 331 of the other column. In other embodiments, there may be at least one row of the plurality of through holes 331 staggered with other rows of the plurality of through holes 331. The projections of the two through holes 331 in the length direction Y of the diaphragm 300 do not overlap, and the two through holes 331 may be regarded as being staggered. For example, the plurality of through holes 331 in one of the two adjacent columns of through holes 331 may be staggered with the plurality of through holes 331 in the other column.

In other embodiments, the incomplete cutting structure 330 may also include a plurality of slots spaced apart from one another. The slit may be obtained by cutting the diaphragm with a cutter or the like.

Referring to fig. 4, when the diaphragm 300 includes the first and second diaphragms 340 and 350, the incompletely cut structure 330 on the first diaphragm 340 is a through hole 331 penetrating the first diaphragm 340. The incompletely cut structure 330 on the second diaphragm 350 is a through hole 331 penetrating the second diaphragm 350. When the incompletely cut structures 330 are disposed on both the first membrane 340 and the second membrane 350, the through holes 331 of the first membrane 340 are disposed opposite to the through holes 331 of the second membrane 350, and the through holes 331 of the first membrane 340 are communicated with the through holes 331 of the second membrane 350.

It can be appreciated that, by providing a plurality of through holes 331 on the diaphragm 300 to form the incompletely cut structure 330, the partial material on the diaphragm 300 is cut off, and the diaphragm 300 is not completely cut along the width direction of the diaphragm 300, compared with the situation that the diaphragm 300 is completely cut off, the diaphragm 300 is not shrunk and wrinkled due to stress variation, and the diaphragm 300 around the through holes 331 is weak, when the free falling body is folded, the diaphragm 300 can be folded along the position of the through holes 331, so that the precise position folding is realized, and the alignment of the negative electrode sheet 100 and the positive electrode sheet 200 in the folded battery cell is facilitated.

In some embodiments, referring to fig. 1 and fig. 7, fig. 7 is a schematic diagram of a thermal composite cell according to an embodiment of the present application. The spacing between any two adjacent through holes 331 is the same. Here, the interval between the adjacent through holes 331 refers to a distance between one side of the through hole 331 and one side of the adjacent through hole 331 along the width direction Z of the diaphragm 300.

In this embodiment, the intervals between adjacent through holes 331 are the same, which is beneficial to processing the through holes 331 on the diaphragm 300, so that the strength of the diaphragm 300 on the straight line where the through holes 331 are located is the same, and the situation that the diaphragm 300 is broken in the folding process due to weak local strength is avoided.

The shape of the through hole 331 is a regular shape of a circle, rectangle, ellipse, hexagon, or octagon. The through holes 331 may be irregularly shaped in addition to being regularly shaped.

In some embodiments, referring to FIG. 7, the spacing between adjacent through holes 331 is S1 along the width direction Z of the diaphragm 300, where 5 mm.ltoreq.S1.ltoreq.20mm. Wherein, the value of S1 can be 5.0mm、5.2mm、5.7mm、7.8mm、9.0mm、10.5mm、11.5mm、12.3mm、13.9mm、14.0mm、15.7mm、16.1mm、17.4mm、18.0mm、19.6mm、20.0mm or other non-listed values.

In the embodiment of the application, the interval S1 between the through holes 331 is set to be more than or equal to 5mm, so that the situation that the structural strength of the diaphragm 300 is affected due to the fact that the distance between the through holes 331 is too small and the number of the through holes 331 is too large can be avoided, and the situation that the interval S1 between the through holes 331 is less than or equal to 20mm, so that the situation that the positioning and folding cannot be performed in the folding process due to the fact that the distance between the through holes 331 is too large and the number of the through holes 331 is relatively small can be avoided. The interval design between the through holes 331 is reasonable, and the folding quality is ensured.

In some embodiments, referring to FIG. 7, the through hole 331 is rectangular in shape, the through hole 331 has a first dimension L1 and a second dimension W1, the first dimension is a distance between two parallel planes virtually abutting the walls of the holes on two sides of the through hole 331, and the second dimension is a distance between two parallel planes virtually abutting the walls of the holes on two sides of the through hole 331, wherein 1 mm.ltoreq.L1.ltoreq.20mm, and/or 1 mm.ltoreq.W1.ltoreq.2mm. The wall of the two sides refers to the side wall extending along the width direction Z of the diaphragm 300, and the wall of the two sides refers to the side wall extending along the length direction Y of the diaphragm 300. In this embodiment, the value of L1 may be 1.1mm、1.2mm、1.5mm、2.3mm、3.4mm、4.2mm、5.0mm、6.8mm、7.8mm、8.8mm、9.0mm、10.3mm、11.1mm、12.5mm、13.8mm、14.1mm、15.0mm、16.6mm、17.7mm、18.2mm、19.1mm、20.0mm or other non-specified values. The value of W1 in this example may be 1.1mm, 1.2mm, 1.4mm, 1.5mm, 1.8mm, 2.0mm or other non-specified values.

It should be noted that, the two parallel planes of the virtual abutment through hole 331 are only introduced for facilitating understanding of the first dimension and the second dimension, and are not actually present in the solution of the present application. For example, the through hole 331 is rectangular in outer outline, to determine a first dimension and a second dimension, two groups of planes may be assumed, where each group of planes includes two parallel planes disposed at intervals, and each group of two parallel planes can jointly virtually abut against two opposite hole walls of the through hole 331, where a distance is provided between each group of two parallel planes, the first dimension is a distance between two planes abutting against two hole walls on two sides of the through hole 331, and the second dimension is a distance between two planes abutting against two hole walls on two ends of the through hole 331.

It can be appreciated that the size of the through hole 331 in this embodiment is designed reasonably, so that the structural strength of the diaphragm 300 is prevented from being affected by the oversized through hole 331, or the through hole 331 is too small in size, and the positioning and folding effects are not achieved in the folding process.

In some embodiments, referring to fig. 1, 5, 6, and 7, the long side dimension of the negative electrode sheet 100 is greater than the long side dimension of the positive electrode sheet 200, and the wide side dimension of the negative electrode sheet 100 is greater than the wide side dimension of the positive electrode sheet 200. In the thermal composite cell, along the thickness direction X of the negative electrode sheet 100, the projection of the positive electrode sheet 200 in the plane of the negative electrode sheet 100 falls completely into the negative electrode sheet 100.

It can be appreciated that the size of the negative electrode sheet 100 is designed to be larger than that of the positive electrode sheet 200, and in the charging process of the lithium battery, the negative electrode sheet 100 can completely receive lithium ions of the positive electrode sheet 200, so that the probability of forming lithium dendrites is reduced, the occurrence of thermal runaway caused by short circuit due to the formation of the lithium dendrites piercing the diaphragm 300 is avoided, and the reliability of the battery is improved.

In some embodiments, referring to FIG. 7, the distance between the long side of the positive electrode sheet 200 and the long side of the negative electrode sheet 100 is S2, and the distance between the wide side of the positive electrode sheet 200 and the wide side of the negative electrode sheet 100 is S3, wherein 1 mm.ltoreq.S2.ltoreq.3mm, 1 mm.ltoreq.S3.ltoreq.3mm. The values of S2 and S3 may be 1mm, 1.3mm, 1.7mm, 1.8mm, 2.0mm, 2.3mm, 2.7mm, 3.0mm or other non-specified values.

The distance S2 between the long side of the positive electrode sheet 200 and the long side of the negative electrode sheet 100 may be the same as or different from the distance S3 between the wide side of the positive electrode sheet 200 and the wide side of the negative electrode sheet 100, and the embodiment is not specifically limited.

It can be appreciated that in this embodiment, the distance S2 between the long side of the positive electrode sheet 200 and the long side of the negative electrode sheet 100 and the distance S3 between the wide side of the positive electrode sheet 200 and the wide side of the negative electrode sheet 100 are reasonable in size design, and on the premise of meeting the safety performance of the battery, the material waste caused by the oversized size is avoided, and the cost is reduced. Because the alignment degree of the lamination battery cells is good, the size of the negative electrode plate 100 exceeding the positive electrode plate 200 can be properly shortened, the material of the negative electrode plate is reduced, and the cost is reduced.

In some embodiments, referring to fig. 1, 4, 6 and 7, the long side dimension of the body portion 310 is greater than the long side dimension of the negative electrode sheet 100, and the wide side dimension of the body portion 310 is greater than the wide side dimension of the negative electrode sheet 100. It will be appreciated that the size of the main body 310 is larger than the size of the negative electrode sheet 100, and the projection of the negative electrode sheet 100 onto the main body 310 falls completely within the continuous planar area enclosed by the outer contour of the main body 310.

The negative plate 100 and the positive plate 200 are separated by the main body 310, if the size of the main body 310 is smaller than that of the negative plate 100, the negative plate 100 and the positive plate 200 may be in direct contact, so that thermal runaway is caused by short circuit, the size of the main body 310 is designed to be larger than that of the positive plate 200, the electrical safety requirement of the thermal composite battery cell is met, and the reliability of the thermal composite battery cell is improved.

In some embodiments, referring to FIG. 7, the distance between the long side of negative electrode sheet 100 and the long side of separator 300 is S4, where 2 mm.ltoreq.S4.ltoreq.4mm, and/or separator 300 includes a start end 360, and the distance between start end 360 and the wide side of negative electrode sheet 100 closest to start end 360 is S5, where 1 mm.ltoreq.S5.ltoreq.3mm. The long side of the negative electrode sheet 100 is a side extending in the longitudinal direction Y of the separator 300, and the wide side of the negative electrode sheet is a side extending in the width direction Z of the separator 300.

In this embodiment, the value of S4 may be 2.1mm, 2.3mm, 2.7mm, 3.0mm, 3.4mm, 3.8mm, 3.9mm, 4mm or other non-specified values.

In this embodiment, the value of S5 may be 1.1mm, 1.2mm, 1.5mm, 1.6mm, 1.8mm, 1.9mm, 2mm, 2.3mm, 2.5mm, 2.7mm, 2.8mm, 2.9mm, 3mm or other non-specified values.

In this embodiment, the values of S4 and S5 may be the same or different, and the embodiment is not specifically limited.

It can be appreciated that the size design of the negative electrode plate and the diaphragm 300 is reasonable, and under the condition of meeting the electrical safety, the condition that the diaphragm 300 is oversized to cause material waste is avoided, and the processing cost is reduced.

In some embodiments, referring to FIG. 4, the thickness of negative electrode current collector 110 is D1,4.0 μm.ltoreq.D1.ltoreq.6.0 μm. D1 may be 4.0 μm, 4.1 μm, 4.7 μm, 5.0 μm, 5.4 μm, 5.6 μm, 6.0 μm or other unlisted values. The thickness of the negative electrode current collector 110 is designed reasonably, and the electrical property requirement of the negative electrode sheet 100 is satisfied.

In some embodiments, the thickness of the anode active layer 120 is D2,50 μm.ltoreq.D2.ltoreq.200 μm. The D2 value may be 50 μm, 65 μm, 72 μm, 89 μm, 95 μm, 108 μm, 117 μm, 122 μm, 136 μm, 144 μm, 159 μm, 162 μm, 175 μm, 187 μm, 198 μm, 200 μm or other values not specified. The thickness of the negative electrode active layer 120 is designed reasonably to meet the electrical requirements of the negative electrode sheet 100.

In some embodiments, the positive electrode sheet 200 includes a positive electrode current collector and a positive electrode active layer, and both sides of the positive electrode current collector are provided with the positive electrode active layer. The material of the positive electrode current collector may be aluminum foil, and the material of the positive electrode active layer may be one or more of lithium cobaltate, lithium nickelate, lithium manganate, lithium nickel cobalt manganate and lithium iron phosphate.

Referring to fig. 1, fig. 2, fig. 3, fig. 4, and fig. 8, an embodiment of the present application further provides a method for preparing a thermal composite electrical core, which is used for preparing the thermal composite electrical core of any one of the above embodiments, including the following steps:

S10, providing N negative electrode sheets 100, M positive electrode sheets 200, a first separator 340 and a second separator 350, N-m=1, wherein N negative electrode sheets 100 include N-2 double-sided electrode sheets 100A and 2 single-sided electrode sheets 100B;

Wherein, both sides of the negative current collector 110 of the double-sided pole piece 100A are provided with a negative active layer 120, and one side of the negative current collector 110 of the single-sided pole piece 100B is provided with a negative active layer 120;

S20, thermally compounding the double-sided pole piece 100A, the positive pole piece 200, the first diaphragm 340 and the second diaphragm 350 to form a compound laminated layer, as shown in FIG. 8, wherein M positive pole pieces 200 are arranged between the first diaphragm 340 and the second diaphragm 350 at intervals, the first diaphragm 340 and the second diaphragm 350 between adjacent positive pole pieces 200 are thermally compounded, the double-sided pole piece 100A is alternately arranged on one side of the first diaphragm 340 away from the positive pole piece 200 and one side of the second diaphragm 350 away from the positive pole piece 200, the double-sided pole piece 100A is arranged in alignment with the positive pole piece 200, an incomplete cutting structure 330 is processed on the compound laminated layer, and the incomplete cutting structure 330 is arranged on the first diaphragm 340 and/or the second diaphragm 350 between the adjacent positive pole pieces 200;

The number of the double-sided pole pieces 100A is one less than that of the positive pole pieces 200, and the double-sided pole pieces 100A are aligned with the positive pole pieces 200, wherein the method comprises the following two conditions that N-2 double-sided pole pieces 100A are aligned with the 2 nd to M positive pole pieces, or N-2 double-sided pole pieces 100A are aligned with the 1 st to M-1 st positive pole pieces;

It can be appreciated that in this embodiment, after the thermal compounding of all the positive electrode sheets 200 with the first separator 340 and the second separator 350 is completed, all the double-sided electrode sheets 100A may be thermally compounded, or the positive electrode sheets 200 and the negative electrode sheets 100 may be alternately thermally compounded with the first separator 340 and the second separator 350 respectively to form a composite laminate;

S30, folding the composite lamination along the straight line where the incomplete cutting structure 330 is located to form a lamination unit, and respectively thermally compounding the 2 single-sided pole pieces 100B at the outermost sides of the lamination unit to prepare the thermal composite battery core. The negative electrode active layer 120 of the negative electrode sheet 100 is bonded to the first separator 340 or the second separator 350.

In this embodiment, the first separator 340, the second separator 350, the negative electrode sheet 100 and the positive electrode sheet 200 are thermally compounded, after the incomplete cutting structure 330 is processed on the first separator 340 and/or the second separator 350, the composite laminate is folded along the incomplete cutting structure 330 in a free falling manner, and the first separator 340 and/or the second separator 350 at the incomplete cutting structure 330 is subjected to small stress, so that the composite laminate is folded along the straight line where the incomplete cutting structure 330 is located in a Z-shaped manner, thereby realizing positioning and folding, and ensuring the alignment degree of the thermal composite battery cell.

In other embodiments, referring to fig. 5 and 6, fig. 5 is a cross-sectional view of a second version of A-A of fig. 2, and fig. 6 is an enlarged view of a portion of fig. 5B. The diaphragm 300 is a single-layer diaphragm, the negative electrode plate 100 and the positive electrode plate 200 are respectively arranged on two sides of the diaphragm 300, all the negative electrode plates 100 are positioned on the same side of the diaphragm 300, all the positive electrode plates 200 are positioned on the same side of the diaphragm 300, the negative electrode plates 100 and the positive electrode plates 200 are arranged at intervals along the length direction of the diaphragm 300, an incomplete cutting structure 330 is arranged on the diaphragm 300 between the adjacent negative electrode plates 100 and positive electrode plates 200, and the diaphragm 300 is folded in a Z shape along the incomplete cutting structure 330, so that the alignment degree of the negative electrode plates 100 and the positive electrode plates 200 in the folded battery cell is ensured.

Referring to fig. 5, 6 and 7, the embodiment of the present application further provides a method for preparing a thermal composite battery cell, which is used for preparing the thermal composite battery cell of the above embodiment, and includes the following steps:

S10, providing N negative electrode sheets 100, M positive electrode sheets 200 and a separator 300, N-m=1, wherein N negative electrode sheets 100 include N-2 double-sided electrode sheets 100A and 2 single-sided electrode sheets;

Wherein, both sides of the negative current collector 110 of the double-sided pole piece 100A are provided with a negative active layer 120, and one side of the negative current collector 110 of the single-sided pole piece 100B is provided with a negative active layer 120;

It can be appreciated that the negative electrode sheet 100 and the positive electrode sheet 200 are obtained by cutting a negative electrode material roll and a positive electrode material roll, respectively, and in the preparation process, all the required N negative electrode sheets 100 and M positive electrode sheets 200 can be cut, or a single negative electrode sheet 100 or positive electrode sheet 200 can be formed by cutting before each negative electrode sheet 100 or positive electrode sheet 200 is thermally compounded;

S20, thermally compounding the double-sided pole pieces 100A, the positive pole pieces 200 and the diaphragm 300 to form a compound lamination, as shown in FIG. 9, wherein all the double-sided pole pieces 100A are thermally compounded on one side of the diaphragm 300, M positive pole pieces 200 are thermally compounded on the other side of the diaphragm 300, the double-sided pole pieces 100A and the positive pole pieces 200 are alternately arranged at intervals along the length direction Y of the diaphragm 300, N-2 double-sided pole pieces 100A are arranged between the 1 st positive pole piece 200 and the M positive pole piece 200;

It can be understood that the separator 300 is a layer of separator, all the double-sided pole pieces 100A are thermally compounded on one side surface of the separator 300, and the M positive pole pieces 200 are thermally compounded on the other side surface of the separator 300, and the gaps between the adjacent negative pole pieces 100 and positive pole pieces 200 are the same;

S30, performing Z-shaped folding on the composite lamination along the straight line where the incomplete cutting structure 330 is located to form a lamination unit, and respectively thermally compounding 2 single-sided pole pieces 100B on the outermost sides of the lamination unit, wherein the negative electrode active layer 120 of the single-sided pole piece 100B is attached to the diaphragm 300, so as to prepare the thermal composite battery cell.

In this embodiment, the separator 300, the negative electrode sheet 100 and the positive electrode sheet 200 are thermally compounded, and after the incompletely cut structure 330 is processed on the separator 300, the composite laminate is folded along the incompletely cut structure 330 in a free falling manner, and the separator 300 at the incompletely cut structure 330 is subjected to small stress in the folding process, so that the composite laminate is folded along the straight line where the incompletely cut structure 330 is located in a Z-type manner, and the folding efficiency is high and the folding quality is good.

In the foregoing embodiments, the descriptions of the embodiments are emphasized, and for parts of one embodiment that are not described in detail, reference may be made to related descriptions of other embodiments.

In the description of the present application, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more features.

While the thermal composite battery cell provided by the embodiment of the present application has been described in detail, specific examples are used herein to illustrate the principles and embodiments of the present application, the above examples are only for aiding in understanding of the method and core concept of the present application, and meanwhile, the present disclosure should not be construed as being limited to the present application, since the skilled person will vary in terms of the detailed description and the application scope according to the concept of the present application.

Claims (18)

1. A thermal composite cell, comprising:

N negative electrode pieces (100), wherein N is a positive integer greater than 1, and negative electrode lugs (130) are arranged on the negative electrode pieces (100);

M positive pole pieces (200), M is a positive integer greater than 1, N-M=1, and positive pole lugs (210) are arranged on the positive pole pieces (200);

A separator (300), wherein the separator (300) comprises a plurality of main body parts (310) and a plurality of bending parts (320) which are alternately and continuously arranged, the negative electrode sheets (100) and the positive electrode sheets (200) are alternately stacked along the thickness direction of the negative electrode sheets (100), the adjacent negative electrode sheets (100) and positive electrode sheets (200) are separated by the main body parts (310), the bending parts (320) are provided with incomplete cutting structures (330), the separator (300) is folded along the incomplete cutting structures (330), and at least partial structures of the negative electrode lugs (130) and the positive electrode lugs (210) are positioned outside the separator (300);

Two of the negative electrode sheets (100) located at the outermost side are single-sided electrode sheets (100B), and the other negative electrode sheets (100) are double-sided electrode sheets (100A).

2. The thermal composite cell of claim 1, wherein the single-sided pole piece (100B) comprises a negative current collector (110) and a negative active layer (120), the negative current collector (110) being disposed adjacent a side of the body portion (310) with the negative active layer (120);

And/or, the double-sided pole piece (100A) comprises a negative electrode current collector (110) and a negative electrode active layer (120), wherein both side surfaces of the negative electrode current collector (110) are provided with the negative electrode active layer (120).

3. The thermal composite cell of claim 1, wherein the membrane (300) comprises a first membrane (340) and a second membrane (350), the first membrane (340) comprises a first body portion (311) and a first bend (321), the second membrane (350) comprises a second body portion (312) and a second bend (322), and the first bend (321) and/or the second bend (322) provides the non-fully severed structure (330).

4. A thermal compound cell as claimed in claim 3, characterized in that the first bending portion (321) and the second bending portion (322) are each provided with the incompletely cut structure (330), and the projection of the incompletely cut structure (330) on the first bending portion (321) onto the second diaphragm (350) overlaps with the incompletely cut structure (330) on the second bending portion (322).

5. The thermal composite cell of any one of claims 1 to 4, wherein the non-fully cut structure (330) comprises a plurality of through holes (331) penetrating the separator (300), the plurality of through holes (331) being arranged at intervals along a width direction of the separator (300).

6. The thermal composite cell of claim 5, wherein the spacing between adjacent vias (331) is the same.

7. The thermal composite cell of claim 5, wherein the through-hole (331) is circular or rectangular in shape.

8. The thermal composite cell of claim 5, wherein a spacing between adjacent through holes (331) along a width direction of the separator (300) is S1, wherein 5mm is equal to or less than S1 is equal to or less than 20mm.

9. The thermal composite cell of claim 5, wherein the through hole (331) has a first dimension L1 and a second dimension W1, the first dimension being a distance between two parallel planes virtually abutting the walls of the holes on both sides of the through hole (331), and the second dimension being a distance between two parallel planes virtually abutting the walls of the holes on both sides of the through hole (331), wherein 1mm is equal to or less than L1 and equal to or less than 20mm, and/or 1mm is equal to or less than W1 and equal to or less than 2mm.

10. The thermal composite cell of any of claims 1 to 4, wherein a long side dimension of the negative electrode sheet (100) is greater than a long side dimension of the positive electrode sheet (200), and a wide side dimension of the negative electrode sheet (100) is greater than a wide side dimension of the positive electrode sheet (200).

11. The thermal composite cell of any one of claims 1 to 4, wherein a distance between a long side of the positive electrode sheet (200) and a long side of the negative electrode sheet (100) is S2, S2 is 1mm or less and 3mm or less;

And/or the distance between the wide edge of the positive electrode sheet (200) and the wide edge of the negative electrode sheet (100) is S3, and S3 is more than or equal to 1mm and less than or equal to 3mm.

12. The thermally composite cell of any of claims 1 to 4, wherein the long side dimension of the body portion (310) is greater than the long side dimension of the negative electrode sheet (100), and the wide side dimension of the body portion (310) is greater than the wide side dimension of the negative electrode sheet (100).

13. The thermal composite cell of claim 12, wherein a distance between a long side of the negative electrode sheet (100) and a long side of the separator (300) is S4, wherein 2mm ∈s4 ∈4mm;

And/or the separator (300) comprises a starting end (360), wherein the distance between the starting end (360) and the wide edge of the negative electrode sheet (100) close to the starting end (360) is S5, and S5 is more than or equal to 1mm and less than or equal to 3mm.

14. The thermal composite cell of claim 2, wherein the negative current collector (110) has a thickness D1,4 μm-D1-6 μm;

And/or, the thickness of the negative electrode active layer (120) is D2, D2 being more than or equal to 50 mu m and less than or equal to 200 mu m.

15. The thermal composite cell of any one of claims 1 to 4, wherein the positive electrode sheet (200) comprises a positive electrode current collector and a positive electrode active layer, the positive electrode active layer being provided on both sides of the positive electrode current collector.

16. The thermal composite cell of any of claims 1 to 4, wherein the negative electrode sheet (100), the positive electrode sheet (200) and the separator (300) are thermally compositely connected.

17. The thermal compound cell according to any one of claims 1 to 4, wherein the projections of all the negative electrode tabs (130) overlap and/or the projections of all the positive electrode tabs (210) overlap in the thickness direction of the negative electrode sheet (100).

18. The thermal compound cell of claim 17, wherein the projections of the negative electrode tab (130) and the positive electrode tab (210) in the plane of the body portion (310) are arranged side by side.