CN219321582U

CN219321582U - Pole piece, electrode assembly, battery monomer, battery and power utilization device

Info

Publication number: CN219321582U
Application number: CN202320795096.XU
Authority: CN
Inventors: 杨振飞
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2023-04-12
Filing date: 2023-04-12
Publication date: 2023-07-07
Anticipated expiration: 2033-04-12

Abstract

The application relates to a pole piece, electrode assembly, battery monomer, battery and power consumption device, the pole piece includes: the pole lug part is provided with a second side, a third side and a fourth side, the second side is parallel to the first side, and the third side and the fourth side are respectively positioned at two sides of the pole lug part along the length direction of the pole piece; at least one of the third side and the fourth side comprises a first section and a second section, one end of the first section is connected with the second side, the other end of the first section is connected with the second section, and the other end of the second section is connected with the first side; when the first section is a straight line and the included angle between the first section and the second side is larger than 90 degrees, the second section is a curve and/or a broken line; when the first section is a curve and the included angle between the first section and the second side is larger than 90 degrees, the second section is a straight line and/or a curve and/or a broken line. The tip of utmost point ear is the obtuse angle in this application, kneads the utmost point ear or smooth at ordinary times, can reduce the probability of electrode assembly internal short circuit, perhaps reduces the probability of casing corruption.

Description

Pole piece, electrode assembly, battery monomer, battery and power utilization device

Technical Field

The application relates to the technical field of batteries, in particular to a pole piece, an electrode assembly, a battery cell, a battery and an electric device.

Background

In the manufacturing process of some battery monomers, after a pole piece (including a cathode piece and an anode piece) and a diaphragm are laminated and wound to form an electrode assembly, the pole lug needs to be flattened or smoothed so as to be convenient for subsequent welding connection with other structures.

However, in the process of flattening or smoothing the tab, the end of the tab is easily inserted into the electrode assembly downward to cause a problem of overlap short circuit, or the end of the tab is easily lifted upward and overlapped with the housing in the subsequent process of inserting the electrode assembly into the housing to cause a problem of corrosion of the housing, which affects the reliability of the electrode assembly after forming the battery cell.

Disclosure of Invention

Based on this, it is necessary to provide a pole piece, an electrode assembly, a battery cell, a battery and an electric device, which are necessary to solve the problem that the end of the tab is easy to be inserted downwards or tilted upwards in the current process of flattening or smoothing the tab, thereby causing the internal short circuit of the electrode assembly or the corrosion of the shell caused in the process of inserting the electrode assembly into the shell.

In a first aspect, the present application provides a pole piece comprising:

a main body portion;

the pole ear part is positioned on at least one side of the main body part along the width direction of the pole piece;

wherein the main body part is provided with a first edge connected with the lug part;

the pole lug part is provided with a second side, a third side and a fourth side, the second side is parallel to the first side, and the third side and the fourth side are respectively positioned at two sides of the pole lug part along the length direction of the pole piece;

at least one of the third side and the fourth side comprises a first section and a second section which are connected with each other, one end of the first section is connected with the second side, the other end of the first section is connected with one end of the second section, and the other end of the second section is connected with the first side;

when the first section is a straight line and the included angle between the first section and the second side is larger than 90 degrees, the second section is a curve and/or a broken line; when the first section is a curve and the included angle between the first section and the second side is larger than 90 degrees, the second section is a straight line and/or a curve and/or a broken line.

Because contained angle between first section and the second limit is greater than 90 degrees, carry out the chamfer to the tip of utmost point ear promptly for the tip of utmost point ear is the obtuse angle setting. Therefore, when the lug part is kneaded or smoothed, the probability that the end part of the lug part which is obtuse angle is lower in inserting or upwarping is smaller, and the distance that the end part of the lug part is lower in inserting or upwarping is smaller due to the constraint effect between the third side and the second side and between the fourth side and the second side, so that the probability that the end part of the lug part is inserted downwards and overlapped with the main body part to cause the electrode assembly to be short-circuited can be reduced, or the probability that the end part of the lug part is upwarping and overlapped with the shell to cause the shell to corrode is reduced.

In some embodiments, the tab portion includes at least two sub-tabs disposed along a length direction of the pole piece, each sub-tab has a second side, a third side, and a fourth side, and the third side and the fourth side are respectively located at two sides of the corresponding sub-tab along the length direction of the pole piece.

For the tab parts of at least two sub-tabs, the angle cutting is carried out on each sub-tab, so that the area of each sub-tab can be reduced, and the stacking compactness of the foil material of the smooth end face is reduced. In addition, the probability of inserting or raising the lug part can be reduced, the distance of inserting or raising the lug part is reduced, and the probability of short circuit or shell corrosion of the electrode assembly caused by inserting or raising the lug part is reduced.

In some embodiments, when the second segment is a broken line, the second segment includes a first sub-segment and a second sub-segment that are perpendicular to each other, one end of the first sub-segment is connected to the first segment, the other end of the first sub-segment is connected to the second sub-segment, and the other end of the second sub-segment is connected to the first edge and perpendicular to the first edge;

when the pole piece is wound to form an electrode assembly, the pole ear part is provided with a kneading feeding amount Y;

the distance Z between the first sub-line segment and the first edge is less than or equal to at least twice the difference between the distance X between the second edge and the first edge and the rubbing-flat feed Y.

Therefore, after the first sub-line segment and the second sub-line segment are flattened or smoothed, the main body part is not contacted after the right-angle bending between the first sub-line segment and the second sub-line segment, and the risk of lap short circuit between the pole ear part and the main body part is reduced.

In some embodiments, the tab portion further includes a retention region connected between each sub-tab and the main body portion in a width direction of the pole piece;

the distance L of the reserved area is smaller than or equal to at least twice the difference between the distance X between the second edge and the first edge and the rubbing feeding amount Y in the width direction of the pole piece.

Therefore, after the pole lug part is flattened or smoothed, the right-angle bending of the reserved area can not contact with the main body part, so that the risk of lap short circuit between the pole lug part and the main body part is reduced.

In some embodiments, the included angle between the first segment and the second edge ranges from 142 degrees to 158 degrees. Therefore, when the lug part is kneaded or smoothed, the probability of downward insertion or upward tilting of the lug end part is smaller, and the distance of downward insertion or upward tilting of the lug end part is smaller due to the constraint effect between the first section and the second section of the third side and/or the fourth side, so that the probability of electrode assembly short circuit caused by overlap joint of the lug end part and the main body part can be reduced, or the probability of shell corrosion caused by overlap joint of the lug end part and the shell is reduced.

In a second aspect, the present application provides an electrode assembly comprising a cathode sheet, an anode sheet, and a separator disposed between the cathode sheet and the anode sheet, at least one of the cathode sheet and the anode sheet being a sheet as described above.

In some embodiments, the cathode sheet, separator, and anode sheet are wound in stacks to form a cylindrical structure.

In a third aspect, the present application provides a battery cell comprising an electrode assembly as described above.

In a fourth aspect, the present application provides a battery comprising a battery cell as described above.

In a fifth aspect, the present application provides an electrical device comprising a battery as described above.

Above-mentioned pole piece, electrode assembly, battery cell, battery and power consumption device, because the contained angle between the third limit and/or fourth limit of utmost point ear and the one end that the second limit is connected is greater than 90 degrees with the second limit, carry out the chamfer to the tip of utmost point ear promptly for the tip of utmost point ear is the obtuse angle setting, when pole piece and diaphragm through coiling formation electrode assembly and rub the utmost point ear or smooth at ordinary times, be obtuse utmost point ear tip portion and insert or upwarp the distance littleer, thereby can reduce the probability that causes the short circuit because of the tip of utmost point ear inserts inside the electrode assembly downwards, perhaps reduce the probability that causes the casing to corrode because of the tip of utmost point ear upwarp and with the casing overlap joint when electrode assembly goes into the shell.

Drawings

FIG. 1 is a schematic structural view of an electrode assembly in one or more embodiments;

FIG. 2 is a schematic structural view of a pole piece in one or more embodiments;

FIG. 3 is a schematic structural view of a pole piece in one or more embodiments;

FIG. 4 is a schematic structural view of a pole piece in one or more embodiments;

FIG. 5 is a schematic structural view of a pole piece in one or more embodiments;

FIG. 6 is a schematic structural view of a pole piece in one or more embodiments;

FIG. 7 is a schematic structural view of a pole piece in one or more embodiments;

fig. 8 is a schematic structural view of a pole piece in one or more embodiments.

Reference numerals illustrate: 100. an electrode assembly; 101. a cathode sheet; 102. anode plates; 103. a diaphragm; 10. a pole piece; 11. a main body portion; 12. a tab portion; 111. a first edge; 121. a second side; 122. a third side; 123. fourth side; 124. sub-tabs; 125. a reserved area; 1221. a first section; 1222. a second section; 1222a, a first sub-line segment; 1222b, a second sub-line segment; a. the width direction of the pole piece; b. the length direction of the pole piece.

Detailed Description

In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is, however, susceptible of embodiment in many other forms than those described herein and similar modifications can be made by those skilled in the art without departing from the spirit of the application, and therefore the application is not to be limited to the specific embodiments disclosed below.

Currently, the application of power batteries is more widespread from the development of market situation. The power battery is not only applied to energy storage power supply systems such as hydraulic power, firepower, wind power and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles, electric automobiles and other fields. With the continuous expansion of the application field of the power battery, the market demand of the power battery is also continuously expanding.

In the construction of a battery, one or more battery cells are typically included, i.e., the battery cell is the smallest unit that constitutes the battery. The plurality of battery monomers can be connected in series or in parallel or in series-parallel connection, and the series-parallel connection refers to that the plurality of battery monomers are connected in series or in parallel.

Further, in the structure of the battery cell, an electrode assembly is further included. Wherein the electrode assembly is a component in which an electrochemical reaction occurs in the battery cell. The electrode assembly is mainly formed by winding or stacking a cathode sheet and an anode sheet, and a separator is generally provided between the cathode sheet and the anode sheet. The portions of the cathode sheet and the anode sheet having active material constitute the main body portion of the electrode assembly, and the portions of the cathode sheet and the anode sheet having no active material respectively form the tab portions.

It should be noted that, the battery cell may include a cylindrical battery cell and a square battery cell according to different molding modes. For the cylindrical battery core, when the electrode plate is processed, the cylindrical battery core comprises a full electrode lug and a die-cut small electrode lug.

The full tab means that the tab is at equal height over the length of the entire pole piece. After the electrode assembly is formed by winding the pole piece with the structure, the pole lug part is required to be shaped in a mechanical rolling or direct extrusion rolling mode, so that a compact end face is formed, and the pole piece is convenient to weld with other structures in the subsequent processing process.

The die cutting of the small tabs refers to cutting the tab parts of the full tab pole pieces into a plurality of equidistant or non-equidistant small tabs by adopting a cutting die or a laser mode. The pole piece of this structure needs to smooth each little utmost point ear in proper order at the in-process of coiling, makes it form the closely knit terminal surface of mutual overlap joint.

The tab end portion located inside the winding direction is easily inserted downward into the interior of the electrode assembly during the flattening or smoothing process, and forms overlap with the main body portion to cause short circuit of the electrode assembly, whether it is a full tab pole piece or a die cut small tab pole piece. In addition, for the full tab pole piece, the tab end part positioned at the outer side of the winding direction is easy to tilt upwards in the rolling process due to unconstrained, and when the electrode assembly is subsequently placed into the shell and forms a battery cell together with the shell, the tab end part tilted upwards is easy to form lap joint with the shell, so that the shell is corroded.

Based on above consideration, in order to solve and rub the flat or smooth in-process, the tip of utmost point ear is inserted inside the electrode assembly downwards easily and forms the overlap joint with the main part, thereby cause the problem of electrode assembly short circuit, perhaps the tip of utmost point ear is upwarp easily and form the overlap joint between follow-up electrode assembly income shell in-process and the casing, thereby cause the problem of casing corruption, the present application provides a pole piece in one or more embodiments, the second limit of utmost point ear is on a parallel with the main part and is set up along the first limit that the length direction of pole piece extends, and the contained angle between the third limit and the second limit of utmost point ear connection between first limit and the fourth limit and the one end and the second limit of being connected is greater than 90 degrees, promptly carry out the chamfer to the tip of utmost point ear, make the tip of utmost point ear be the obtuse angle setting.

Therefore, when the lug parts are kneaded or smoothed, the distance between the end parts of the lug parts which are obtuse angles and inserted downwards or tilted upwards is smaller, so that the probability of short circuit caused by the fact that the end parts of the lug parts are inserted downwards into the electrode assembly can be reduced, or the probability of shell corrosion caused by the fact that the end parts of the lug parts tilt upwards and overlap with the shell when the electrode assembly is put into the shell is reduced.

In addition, some embodiments of the present application disclose a battery cell that may be used in, but not limited to, electrical devices such as vehicles, boats, or aircraft. The power supply system with the battery cell, the battery and the like disclosed by some embodiments of the application can be used for forming the power utilization device, so that the probability of short circuit caused by the fact that the end part of the lug part in the battery cell is inserted into the battery core assembly is reduced, or the probability of shell corrosion caused by the fact that the end part of the lug part is upturned and is overlapped with the shell when the electrode assembly is put into the shell is reduced.

Some embodiments of the present application provide an electrical device using a battery as a power source, which may be, but is not limited to, a cell phone, a tablet, a notebook computer, an electrical toy, an electrical tool, a battery car, an electrical car, a ship, a spacecraft, and the like. Among them, the electric toy may include fixed or mobile electric toys, such as game machines, electric car toys, electric ship toys, electric plane toys, and the like, and the spacecraft may include planes, rockets, space planes, and spacecraft, and the like.

In some embodiments, the present application provides an electrical device comprising a battery. The battery comprises a plurality of battery cells, wherein the plurality of battery cells can be connected in series or in parallel in the battery, and the series-parallel connection means that the plurality of battery cells are connected in series or in parallel. The battery units can be directly connected in series or in parallel or in series-parallel connection to form an integral structure, or the battery units can be connected in series or in parallel or in series-parallel connection to form a battery module, and the battery modules are connected in series or in parallel or in series-parallel connection to form an integral structure. Of course, the battery may also include other structures, such as a bus member for making electrical connection between the plurality of battery cells.

The battery cell refers to the smallest unit constituting the battery, and in the structure of the battery cell, the electrode assembly is included. Wherein the electrode assembly is a component in which an electrochemical reaction occurs in the battery cell. The electrode assembly is mainly formed by winding or stacking a cathode sheet and an anode sheet, and a separator is generally provided between the cathode sheet and the anode sheet. The parts of the cathode plate and the anode plate with active substances form a main body part, and the parts of the cathode plate and the anode plate without active substances form pole lug parts. During charge and discharge of the battery, the cathode active material and the anode active material react with the electrolyte, and the tab portion is connected to the electrode terminal to form a current loop.

Referring to fig. 1, the present application provides an electrode assembly 100 including a cathode sheet 101, an anode sheet 102, and a separator 103 disposed between the cathode sheet 101 and the anode sheet 102.

In practical applications, the cathode sheet 101 is usually made of aluminum foil, and the anode sheet 102 is usually made of copper foil, so that the thickness of the anode sheet 102 is greater than that of the cathode sheet 101. Accordingly, the probability of the tab portion 12 of the cathode tab 101 being inserted down or tilted up is relatively high, and the cathode tab 101 may be configured as the electrode tab 10 as described above, to reduce the probability of the tab portion 12 of the cathode tab 101 being inserted down or tilted up, thereby causing the electrode assembly 100 to be short-circuited or the case of the battery cell to be corroded.

In some embodiments, the cathode sheet 101, the separator 103, and the anode sheet 102 are stacked and wound to form a cylindrical structure, i.e., the electrode assembly 100 is a cylindrical cell.

When the tab portion 12 of the electrode assembly 100 is flattened or smoothed, on the one hand, the probability of the tab portion 12 being inserted downward or tilted upward to cause the electrode assembly 100 to be short-circuited or the case of the battery cell to be corroded can be reduced. On the other hand, the stacking compactness of the foil materials on the end faces which are kneaded or smoothed can be reduced, so that the number and the width of channels between the foil materials are increased, the water removal rate is improved, the rate of electrolyte entering the pole pieces 10 is improved, and the soaking time is shortened. In addition, the capacity of electrolyte entering the pole pieces 10 in the later period of battery monomer circulation can be improved, and the probability of local lithium precipitation is reduced.

Referring to fig. 2, in some embodiments, a pole piece 10 is provided, the pole piece 10 may be at least one of the cathode piece 101 and the anode piece 102 described above. Pole piece 10 includes a main body portion 11 and a pole ear portion 12. The tab portion 12 is located on at least one side of the main body portion 11 in the width direction a of the pole piece, and the main body portion 11 has a first side 111 connected to the tab portion 12. The pole ear 12 has a second side 121, a third side 122 and a fourth side 123, the second side 121 is parallel to the first side 111, and the third side 122 and the fourth side 123 are respectively located at two sides of the pole ear 12 along the length direction b of the pole piece. One end of the third side 122 and the fourth side 123 are connected with the second side 121, the other end is connected with the first side 111, and an included angle theta between one end of the third side 122 and the fourth side 123 connected with the second side 121 and the second side 121 is larger than 90 degrees.

The main body 11 is a portion of the pole piece 10 having an active material. The tab portion 12 is a portion of the pole piece 10 having no active material. When the active material is applied, the active material is applied to the middle position of the pole piece 10 in the width direction of the pole piece 10 to form the body portion 11. Accordingly, the active material-uncoated tab portion 12 is naturally formed on at least one side of the main body portion 11 in the width direction a of the pole piece.

Since the main body 11 and the tab portion 12 are formed on the same pole piece 10, the first side 111 of the main body 11 is an edge coated with an active material, and the second side 121 of the tab portion 12 is a side in the pole piece length direction.

In the initial state, the tab portion 12 is rectangular, and the tab portion 12 in the initial state can be cut by a cutter die stamping or a laser die cutting or other cutting modes, so that a third side 122 and a fourth side 123 of the tab portion 12 respectively intersect with the first side 111 and the second side 121, and an included angle between one end, connected with the second side 121, of the third side 122 and the fourth side 123 is larger than 90 degrees.

Thus, the third side 122 of the tab portion 12 after the corner cut forms an obtuse angle with the second side 121 or the fourth side 123 with the second side 121. After the electrode sheet 10 (including the cathode sheet and the anode sheet) and the separator are laminated and wound, the tab portion 12 is flattened or smoothed, and compared with a right angle or an acute angle, the third side 122 and the second side 121 or the fourth side 123 and the second side 121 on both sides of the obtuse angle can form a larger constraint on the obtuse angle top angle, so that the distance that the top angle is inserted into the electrode assembly downwards is reduced, and the probability of short circuit of the electrode assembly caused by overlapping of the tab portion 12 and the main body portion 11 is reduced. Or the height of the upturned apex angle is reduced, thereby reducing the probability of the tab portion 12 overlapping the housing and causing corrosion of the housing when the electrode assembly is subsequently placed into the housing to form a battery cell.

Alternatively, the angle of the angle Θ between the end of the third side 122 connected to the second side 121 and the second side 121 may be set to be between 142 degrees and 158 degrees, and the angle Θ between the end of the fourth side 123 connected to the second side 121 and the second side 121 may be set to be between 142 degrees and 158 degrees. Experiments prove that the included angle theta is arranged in the range, the constraint effect of the third side 122 and the second side 121 or the fourth side 123 and the second side 121 on the top end of the included angle can be effectively improved, the distance of inserting or raising the top end when rubbing or smoothing is reduced, the probability of electrode assembly short circuit caused by overlapping of the lug part 12 and the main body part 11 is reduced, and the probability of shell corrosion caused by overlapping of the lug part 12 and the shell is reduced.

Through the above structure, since the angle Θ between the second side 121 and the third side 122 and the fourth side 123 of the tab portion 12 are greater than 90 degrees, that is, the end portion of the tab portion 12 is cut, the end portion of the tab portion 12 is arranged at an obtuse angle. Therefore, when the lug 12 is kneaded or smoothed, the probability that the end part of the lug 12 with an obtuse angle is inserted downwards or lifted upwards is smaller, and the distance that the end part of the lug 12 is inserted downwards or lifted upwards is smaller due to the constraint action of the third side 122 and the second side 121 or the fourth side 123 and the second side 121, so that the probability that the end part of the lug 12 is inserted downwards and overlapped with the main body part 11 to cause the electrode assembly to be short-circuited can be reduced, or the probability that the end part of the lug 12 is lifted upwards and overlapped with the shell to cause the shell to be corroded can be reduced.

In the structure of the cylindrical battery core, the structure according to the tab can be divided into two tab structures of a full tab and a die-cut small tab, when the tab 12 is a full tab, the tab 12 only comprises one sub-tab 124, and the two ends of the sub-tab 124 along the length direction b of the pole piece are cut.

The pole piece 10 may be classified into a thin coated pole piece and a thick coated pole piece according to the thickness of the coated active material when the active material is coated. Wherein the thick coating pole piece is the thickness of a conventional pole piece, and the thickness range is about 200 mu m-300 mu m. However, with the increasing demand for battery performance, in order to increase the charge-discharge power of the battery cell, it is possible to more easily release or charge energy by coating as much active material in a larger range of the electrode sheet, i.e., a larger specific surface area. Thereby, the thickness of the pole piece becomes thinner, for example 150 μm or even 100 μm.

For the thin coated pole piece, the pole ears 12 in the full pole ear structure are too tightly distributed in the winding process, and the rubbing end face after rubbing is too tightly distributed. Thus, in the laser welding process, if the power of the laser welding is small, the tightly packed flat end faces are difficult to melt, and thus difficult to form connection with other structures (such as a current collecting plate), resulting in insufficient welding strength. If the laser welding power is high, a sharp and deep molten pool is formed, and the diaphragm is directly burnt.

Further, if the kneading feed amount is simply reduced, uneven mass distribution of the inner and outer ring kneading layers is caused, and the weldable area is reduced to affect the overcurrent capability. In addition, the kneading end face is too tight, which also easily causes the reduction of the water removal and infiltration efficiency of the battery cell.

Based on this, when the pole piece 10 is a full-tab pole piece, the third side 122 is located at two sides of the sub-tab 124 along the length direction b of the pole piece, and an included angle Θ between one end of the third side 122 connected with the second side 121 and the second side 121 is greater than 90 degrees.

Thus, in the rubbing process, on the one hand, the stacking compactness of the rubbing end faces can be reduced, so that the number and width of channels between every two adjacent layers of wound pole pieces 10 are increased. On the other hand, the probability of inserting or tilting the tab portion 12 downward can be reduced, the distance of inserting or tilting the tab portion 12 downward can be reduced, and the probability of shorting or corrosion of the case of the electrode assembly 100 due to inserting or tilting the tab portion 12 downward can be reduced.

Referring to fig. 3, in some embodiments, the tab portion 12 includes at least two sub-tabs 124 disposed along a length direction b of the pole piece, each sub-tab 124 has a second side 121, a third side 122 and a fourth side 123, and the third side 122 and the fourth side 123 are respectively located at two sides of the corresponding sub-tab 124 along the length direction b of the pole piece.

When the tab portion 12 is cut into at least two sub-tabs 124, the sub-tabs 124 are arranged in an equidistant or non-equidistant manner along the length direction of the pole piece 10. At this time, each sub-tab 124 has a second side 121, a third side 122 and a fourth side 123, and an angle Θ between an end of each sub-tab 124, where the third side 122 and the fourth side 123 are connected to the second side 121, and the second side 121 is greater than 90 degrees.

Because each sub-tab 124 is subjected to corner cutting treatment, the area of each sub-tab 124 is reduced, and when the electrode is smoothed, the stacking compactness of foils of the smoothed end faces of all sub-tabs 124 can be reduced, so that the number and the width of channels between the foils are increased, the water removal rate of a battery monomer can be improved, the rate of electrolyte entering the electrode slices 10 can be improved, and the soaking time is shortened. In addition, the capacity of electrolyte entering the pole pieces 10 in the later period of battery monomer circulation can be improved, and the probability of local lithium precipitation is reduced.

Further, when the tab portion 12 includes at least two sub-tabs 124 disposed along the length direction b of the pole piece, the spacing H between each adjacent two sub-tabs 124 may be set to be less than or equal to 400 millimeters.

It should be noted that, as shown in fig. 3, the distance H between each two adjacent sub-tabs 124 specifically refers to a distance between an end point of the third side 122 of each sub-tab 124 connected to the second side 121 and an end point of the fourth side 123 of the adjacent sub-tab 124 connected to the second side 121 in the length direction b of the pole piece.

Since the tab portion 12 is used for providing a flow passage for the active material on the main body portion 11, when the interval H between two adjacent sub-tabs 124 is too large, the active material in the local area corresponding to the interval cannot flow directly, but needs to flow through one of the adjacent sub-tabs 124 at a longer distance, so that the problem of uneven polarization occurs at a position on the main body portion 11 further from the sub-tab 124.

In this way, the space H between every two adjacent sub-tabs 124 is set to 400 mm or less, so that the stacking compactness of the flattened end faces can be reduced as much as possible without affecting the direct overcurrent of the active material on the main body 11.

It can be appreciated that the pole pieces 10 with different specifications have different characteristics, and the spacing between every two adjacent sub-tabs 124 can be adjusted according to the actual situation of the different pole pieces 10, which is not limited to the above-mentioned setting range.

As shown in fig. 2 and 4, in some embodiments, at least one of the third side 122 and the fourth side 123 may be configured as a curve connected between the second side 121 and the first side 111. Wherein the curve may comprise an arc or a wavy line. When the third side 122 and/or the fourth side 123 are/is set to be curved, the angle between the third side 122 and the second side 121 or the angle between the fourth side 123 and the second side 121 is actually the angle between the second side 121 and the connecting line between the two points A, B. Where a is the intersection of the third side 122 and the first side 111 or the intersection of the fourth side 123 and the first side 111, and B is the intersection of the third side 122 and the second side 121 or the intersection of the fourth side 123 and the second side 121.

In yet another embodiment, as shown in fig. 5, the third side 122 and the fourth side 123 may be configured as a combination of straight lines and curved lines.

It can be appreciated that when the tab portion 12 includes at least two sub-tabs 124 disposed along the length direction b of the pole piece, that is, when the pole piece 10 is a die-cut small-tab pole piece 10, the third side 122 and the fourth side 123 may also be configured as a curve or a combination of a straight line and a curve, which has the same effect as the full-tab pole piece 10, and will not be described herein.

In the above structure, the curve can further reduce the sharpness of the angle between the third edge 122 and the second edge 121 or between the fourth edge 123 and the second edge 121, and further reduce the distance of downward insertion or upward tilting of the tab portion 12.

Referring to fig. 6, in some embodiments, at least one of the third side 122 and the fourth side 123 includes a first section 1221 and a second section 1222 connected to each other, one end of the first section 1221 is connected to the second side 121, the other end of the first section 1221 is connected to one end of the second section 1222, and the other end of the second section 1222 is connected to the first side 111. When the first segment 1221 is a straight line and the angle Θ with the second edge 121 is greater than 90 degrees, the second segment 1222 is a curve and/or a polyline. When the first segment 1221 is curved and the angle Θ with the second edge 121 is greater than 90 degrees, the second segment 1222 is a straight line and/or curve and/or broken line.

Specifically, the first section 1221 is disposed to intersect the second section 1222. When the first section 1221 is provided as a straight line, the second section 1222 may be provided as a curved line or a broken line. At this time, the angle between the third side 122 and the second side 121 or the angle between the fourth side 122 and the second side 121 is actually the angle between the first section 1221 and the second side 121.

When the first section 1221 is set to a curve, the second section 1222 may be set to a straight line or a curve or a broken line. At this time, the angle between the first segment 1221 and the second edge 121 is actually the angle between the line between the two points C, D and the second edge 121. Where C is the intersection between the first segment and the second segment and D is the intersection between the first segment 1221 and the second edge 121.

When the first section 1221 is provided as a combination of a straight line and a curved line, the second section 1222 may also be provided as a straight line or a curved line or a broken line. At this time, the angle between the first segment 1221 and the second edge 121 is actually the angle between the straight line segment in the first segment 1221 and the second edge 121.

Referring to fig. 7, in some embodiments, when the second segment 1222 is a folding line, the second segment 1222 includes a first sub-segment 1222a and a second sub-segment 1222b perpendicular to each other, one end of the first sub-segment 1222a is connected to the first segment 1221, the other end of the first sub-segment 1222a is connected to the second sub-segment 1222b, and the other end of the second sub-segment 1222b is connected to the first edge 111 and perpendicular to the first edge 111. When the electrode assembly 100 is formed by winding the pole piece 10, the lug portion 12 has a roll-off feeding amount Y. The distance Z between the first sub-line segment 1222a and the first edge 111 is less than or equal to at least twice the difference between the distance X between the second edge 121 and the first edge 111 and the roll-off feed amount Y.

The kneading feed amount Y is a distance by which the tab portion 12 is compressed toward the body portion 11 during the kneading or smoothing process.

The first sub-line segment 1222a and the second sub-line segment 1222b in the second segment 1222 are perpendicular to each other, i.e. the angle between the first sub-line segment 1222a and the second sub-line segment 1222b is a right angle. Specifically, during processing, the tab portion 12 may be cut by laser film cutting or knife die punching cutting so that the tab portion 12 is formed into the above-described shape.

When the angle between the first sub-line segment 1222a and the second sub-line segment 1222b is a right angle, in order to reduce the risk of the right angle being bent during the rubbing or smoothing process to overlap the main body 11 to form a short circuit, the following relationship needs to be satisfied by the distance Z between the rubbing feeding amount Y and the first sub-line segment 1222a and the first side 111, and the distance X between the first side 111 and the second side 121: z is less than or equal to 2 (X-Y).

Thus, after the rubbing or smoothing, the right angle between the first sub-line segment 1222a and the second sub-line segment 1222b is bent, and the main body 11 is not touched, so that the risk of overlapping short circuit between the tab portion 12 and the main body 11 is reduced.

Referring to fig. 8, in other embodiments, the tab portion 12 further includes a reserved area 125 connected between each sub-tab 124 and the main body portion 11 along the width direction a of the pole piece. When the electrode assembly 100 is formed by winding the pole piece 10, the lug portion 12 has a roll-off feeding amount Y. The distance L of the holding area 125 in the width direction a of the pole piece is less than or equal to at least twice the difference between the distance X between the second edge 121 and the first edge 111 and the roll-off feeding amount Y.

Specifically, when the tab portion 12 is chamfered, the third side 122 or the fourth side 123 may not extend to be connected to the first side 111. That is, the tab portion 12 after the corner cutting includes each sub-tab 124 and a reserve area 125 connected between each sub-tab 124 and the main body portion 11 in the width direction a of the pole piece.

Further, since the two ends of the retention area 125 in the length direction b of the pole piece are right angles, in order to reduce the risk that the right angles are bent to overlap the main body 11 during the flattening or smoothing process to form a short circuit, the distance L between the flattening feeding amount Y and the retention area 125 in the width direction of the pole piece 10, and the distance X between the first side 111 and the second side 121 need to satisfy the following relationship: l is less than or equal to 2 (X-Y).

Thus, after flattening or smoothing, the right-angle bend of the retention region 125 does not contact the main body 11, thereby reducing the risk of overlap shorting of the tab portion 12 and the main body 11.

Based on the same concept as the electrode assembly 100 described above, the present application provides a battery cell including the electrode assembly 100 as described above.

Based on the same concept as the above battery cell, the present application provides a battery including the battery cell as described above.

Based on the same concept as the above battery, the present application provides an electric device including the battery as described above.

According to some embodiments, during processing of pole piece 10, tab ear 12 of pole piece 10 is chamfered such that the angle between third side 122 and/or fourth side 123 of tab ear 12 and second side 121 is greater than 90 degrees. Specifically, the angle between the third side 122 and the second side 121 is set at 142 ° -158 °, and/or the angle between the fourth side 123 and the second side 121 is set at 142 ° -158 °, such that the tab portion 12 has one or more trapezoidal structures disposed at intervals. The electrode sheet 10 (including the cathode sheet 101 and the anode sheet 102) is then laminated with the separator 103, and wound to form the electrode assembly 100.

After winding, the tab portion 12 is flattened or smoothed to form a relatively dense end face for subsequent welding.

Thus, the obtuse angle formed between the third side 122 and the second side 121 or between the fourth side 123 and the second side 121 of the tab portion 12 can reduce the distance by which the tab portion 12 is inserted downward into the interior of the electrode assembly 100 or the distance by which the tab portion 12 is lifted upward during the rubbing or smoothing process. Thereby reducing the probability of short circuit caused by the insertion of the tab portion 12 down and overlap with the main body portion 11, or reducing the probability of corrosion of the case caused by the overlap of the tab portion 12 and the case when the electrode assembly 100 is mounted in the case.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples only represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the claims. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.

Claims

1. A pole piece, comprising:

a main body portion;

a tab portion located on at least one side of the main body portion in a width direction of the pole piece;

wherein the body portion has a first edge connected to the tab portion;

when the first section is a straight line and the included angle between the first section and the second side is larger than 90 degrees, the second section is a curve and/or a broken line;

when the first section is a curve and the included angle between the first section and the second side is larger than 90 degrees, the second section is a straight line and/or a curve and/or a broken line.

2. The pole piece of claim 1, wherein the pole ear portion comprises at least two sub-pole ears disposed along a length direction of the pole piece, each sub-pole ear has the second side, the third side and the fourth side, and the third side and the fourth side are respectively located at two sides of the corresponding sub-pole ear along the length direction of the pole piece.

3. The pole piece of claim 1, wherein when the second segment is a fold line, the second segment comprises a first sub-segment and a second sub-segment that are perpendicular to each other, one end of the first sub-segment is connected to the first segment, the other end of the first sub-segment is connected to the second sub-segment, and the other end of the second sub-segment is connected to the first edge and perpendicular to the first edge;

wherein, when the pole piece is wound to form an electrode assembly, the pole ear part is provided with a kneading feeding amount Y;

the distance Z between the first sub-line segment and the first edge is less than or equal to at least twice the difference between the distance X between the second edge and the first edge and the rubbing feeding Y.

4. The pole piece of claim 2, wherein the tab portion further comprises a retention region connected between each of the sub-tabs and the main body portion in a width direction of the pole piece;

5. The pole piece of claim 1, wherein the angle between the first segment and the second edge is in the range of 142 degrees to 158 degrees.

6. An electrode assembly comprising a cathode sheet, an anode sheet, and a separator disposed between the cathode sheet and the anode sheet, wherein at least one of the cathode sheet and the anode sheet is the sheet of any one of claims 1-5.

7. The electrode assembly of claim 6, wherein the cathode sheet, the separator, and the anode sheet are stacked and wound to form a cylindrical structure.

8. A battery cell comprising the electrode assembly of claim 6 or 7.

9. A battery comprising the battery cell of claim 8.

10. An electrical device comprising the battery of claim 9.