Battery pole piece, battery cell, battery, battery module, battery pack and power-consuming device

Abstract

The present application relates to the field of battery technology, and in particular to a battery pole piece, a battery cell, a battery, a battery module, a battery pack and an electrical device. The battery pole piece includes a current collector, an active slurry layer, a non-conductive slurry layer and a pole ear. Along the length direction of the current collector, multiple sections of active slurry layers and multiple sections of non-conductive slurry layers are alternately coated on the current collector, and the pole ear is electrically connected to the current collector. The present application discloses a battery pole piece that alternately coats an active slurry layer and a non-conductive slurry layer on the surface of the current collector, which can ensure the uniformity of the extension of the battery pole piece in the area coated with the active slurry layer and the area coated with the non-conductive slurry layer, thereby solving the problem of cold-pressed fracture of the battery pole piece. Compared with a battery pole piece that is continuously coated with an active slurry layer, such a battery pole piece can reduce battery polarization, improve rate performance, cycle performance and low-temperature performance, and can also reduce the risk of lithium plating at the corners of the wound battery, thereby improving the safety performance of the battery.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery pole piece, a battery cell, a battery, a battery module, a battery pack and an electrical device. Background Art

[0002] Traditional square wound pole pieces use a continuous coating method to evenly coat the slurry on the current collector. After such pole pieces are wound and hot-pressed, lithium is easily deposited at the corners during battery use. In the related art, there are also square wound pole pieces prepared by intermittent coating. Such square wound pole pieces generally reserve blank gaps at the corners of the wound battery cell, which can overcome the problems of increased polarization and lithium deposition at the corners during battery use. However, during the cold pressing process, the pole pieces using this intermittent coating method may break due to uneven extension of the coated and uncoated areas. Summary of the invention

[0003] The present application provides a battery pole piece, a battery cell, a battery, a battery module, a battery pack and an electrical device, which are used to solve the problem of pole piece cold pressing breakage caused by uneven extension of the coating area during the cold pressing process of the existing battery pole piece.

[0004] According to the first aspect of the present application, the present application provides a battery pole piece, which includes a current collector, an active slurry layer, a non-conductive slurry layer and a pole ear. Along the length direction of the current collector, multiple sections of active slurry layers and multiple sections of non-conductive slurry layers are alternately coated on the current collector, and the pole ear is electrically connected to the current collector.

[0005] By alternately coating the active slurry layer and the non-conductive slurry layer on the surface of the current collector, the uniformity of the extension of the battery pole piece in the area coated with the active slurry layer and the area coated with the non-conductive slurry layer can be ensured, thereby solving the problem of cold-pressed fracture of the battery pole piece. In addition, compared with the battery pole piece with continuous coating of the active slurry layer, the battery pole piece of the present application intermittently coats the active slurry layer on the surface of the current collector, which can reduce the polarization of the battery, solve the problem of increased polarization of the battery caused by continuous coating of the slurry on the current collector, improve the battery rate performance, cycle performance and low temperature performance, and reduce the risk of lithium plating at the corners of the wound battery, thereby improving the safety performance of the battery.

[0006] In a possible design, the thickness D1 of the active paste layer and the thickness D2 of the non-conductive paste layer satisfy: 0<D2≤D1.

[0007] By limiting the thickness D2 of the non-conductive slurry layer to be greater than zero and less than or equal to the thickness D1 of the active slurry layer, the portion coated with the non-conductive slurry layer can have a certain degree of ductility, preventing the battery pole piece from breaking from the portion not coated with the active slurry layer during the curling process. If the thickness D2 of the non-conductive slurry layer is greater than the thickness D1 of the active slurry layer, a gap will be generated when the battery pole piece cooperates with other pole pieces during the preparation of the battery cell, affecting the assembly of the battery cell.

[0008] In a possible design, the lengths of the various sections of the active slurry layer are unequal or equal; the lengths of the various sections of the non-conductive slurry layer are unequal or equal.

[0009] By limiting the length of each section of the active slurry layer and the length of each section of the non-conductive slurry layer, the prepared battery pole piece 1 has good applicability in both wound-type battery cells and stacked-type battery cells.

[0010] In a possible design, the tab is connected to the position where the current collector is coated with the active slurry layer, and one tab corresponds to one or two sections of the active slurry layer.

[0011] By connecting the pole ear to the position where the current collector is coated with the active slurry layer, it can be ensured that the pole ear is not affected by the winding process of the battery pole sheet. By corresponding one pole ear to one or two sections of active slurry layer, the preparation requirements of different battery cells can be met, thereby improving the applicability of the battery pole sheet.

[0012] In one possible design, the active slurry layer and the non-conductive slurry layer are coated on the current collector by intermittent coating.

[0013] By adopting an intermittent coating method, the active slurry layer and the non-conductive slurry layer can be effectively coated on the current collector to avoid the problem of increased polarization of the battery, improve the battery rate performance, cycle performance and low temperature performance, reduce the risk of lithium plating at the corners of the wound battery, and improve the safety performance of the battery.

[0014] In one possible design, the active paste layer and the non-conductive paste layer are coated on both sides of the current collector.

[0015] By coating the active slurry layer and the non-conductive slurry layer on both sides of the current collector, it is helpful to reduce the polarization effect of the battery and improve the consistency, safety, cycle life, rate performance and low temperature performance of the battery.

[0016] In a possible design, the non-conductive paste in the non-conductive paste layer is prepared from the following raw materials in parts by weight: 80-95 parts of non-conductive nanomaterials, 5-20 parts of binders, and 43-150 parts of solvents.

[0017] In one possible design, the non-conductive nanomaterial must satisfy one or more of the following properties: (1) Resistivity > 10 2 Ω / cm; (2) acid and alkali resistant; (3) hardness ≥ 3 Mohs; (4) elongation ≤ 1%; (5) insoluble in water or organic solvents; (6) thermal stability > 850℃.

[0018] In one possible design, the non-conductive nanomaterial is selected from one or more of Al2O3, ZrO2, SiO2, CaSiO3, Al4C3, SiC, B4C, AlN, BN, and CaCO3.

[0019] By limiting the components of the non-conductive slurry in the non-conductive slurry layer and the ratio between the components, and the properties and types of the non-conductive nanomaterials in the non-conductive slurry, the non-conductive slurry layer can have resistivity, acid and alkali resistance, hardness, elongation, solubility, thermal stability and other properties that are suitable for the application environment and use conditions of the battery, so that the battery pole piece will not have the problem of cold pressing and breaking at the non-conductive slurry layer.

[0020] According to a second aspect of the present application, the present application provides a battery cell, comprising a negative electrode sheet and a positive electrode sheet that cooperate with each other, and one or both of the negative electrode sheet and the positive electrode sheet are the above-mentioned battery electrodes.

[0021] In a possible design, the battery cell is a wound battery cell, which is formed by winding a negative electrode sheet, a positive electrode sheet, and a separation layer spaced between the negative electrode sheet and the positive electrode sheet; the lengths of the active slurry layers are different, the lengths of the non-conductive slurry layers are different, and along the length direction of the current collector, the lengths of the active slurry layers increase successively, and the lengths of the non-conductive slurry layers increase successively;

[0022] The length of each section of the active slurry layer satisfies the following formula:

[0023] G1=L / 2-b+(H1-K1) / 2,

[0024] G n-1 =L / 2+(H n-2 -K n-2 ) / 2+(H n-1 -K n-1 ) / 2,

[0025] G n =L / 2+(H n-1 -K n-1 ) / 2;

[0026] Among them, G1, G n-1 , G n Respectively represent the length of the first active slurry layer, the length of the n-1th active slurry layer, and the length of the nth active slurry layer; n≥2;

[0027] L represents the circumference of the winding needle of the wound battery cell;

[0028] b represents the length reserved for the head of the battery pole piece when forming a wound battery cell; b satisfies: 10mm≤b≤30mm;

[0029] H1, H n-1 , H n-2 They respectively represent the length of the semicircular arc formed at the first corner, the length of the semicircular arc formed at the n-1th corner, and the length of the semicircular arc formed at the n-2th corner from the inside to the outside when the battery electrode forms a wound battery cell;

[0030] K1, K n-1 , K n-2 They respectively represent the length of the non-conductive slurry layer formed at the first corner from the inside to the outside of the battery electrode when forming a wound battery cell, the length of the n-1th section of the non-conductive slurry layer, and the length of the n-2th section of the non-conductive slurry layer.

[0031] By using a formula to define the length of each active slurry layer, and along the length direction of the current collector, the length of the active slurry layer increases successively, and the length of the non-conductive slurry layer increases successively, so that the active slurry layer and the non-conductive slurry layer can be located at the turning point of the battery cell during winding, thereby reducing the polarization effect at the turning point and enhancing the improvement effect on the battery performance.

[0032] In a possible design, the center angle θ of the semicircular arc formed by the non-conductive slurry layer at the corner of the wound battery cell satisfies: 30°≤θ≤90°.

[0033] By limiting the range of the center angle θ of the semicircular arc formed by the non-conductive slurry layer at the corner of the wound battery cell, it is ensured that the non-conductive slurry layer is completely located at the corner of the battery cell during winding, thereby further reducing the polarization effect at the corner and enhancing the improvement effect on battery performance. Under the condition that the center angle θ of the semicircular arc formed by the non-conductive slurry layer at the corner of the wound battery cell is limited to 30°≤θ≤90°, it can be obtained that the length K of the non-conductive slurry layer at the corner of the wound battery cell n Satisfaction: H n / 6≤K n =θ*H n / 180≤H n / 2. It should be noted that H n It represents the length of the semicircular arc formed from the inside to the outside at the nth corner when the battery pole piece forms a wound battery cell. The angle is used to define the proportion of the coating area length to the total arc length. Then the coating length of the non-conductive slurry at the corner is H. n / 6≤K n ≤H n / 2, or H n / 6≤Kn =θ*H n / 180≤H n / 2.

[0034] In a possible design, the semicircular arc length H formed by the battery pole piece at the nth corner when forming a wound battery cell is n =Π*d n / 2, where d n is the diameter of the semicircle formed by the battery pole piece at the nth corner when forming a wound battery cell;

[0035] When n=1, d1=(mS+2S+2A) / 1000; when n≥2, d n =(mS+2S+2A+(2S+A+C)*(n-1)) / 1000; where d n The unit is mm, m is the number of isolation layers; S is the thickness of the isolation layer, in μm; A is the thickness of the negative electrode sheet, in μm; C is the thickness of the positive electrode sheet, in μm.

[0036] The semicircle diameter d formed by the battery pole piece at the nth corner when forming a wound battery cell n The value of can be used to calculate the length H of the semicircular arc formed by the battery electrode 1 at the nth corner when forming a wound battery cell. n The diameter d of the semicircle formed by the battery pole piece at the nth corner when forming a wound battery cell n It can be obtained based on the values ​​of the thickness S of the isolation layer, the thickness A of the negative electrode sheet, and the thickness C of the positive electrode sheet.

[0037] In a possible design, when both the negative electrode sheet and the positive electrode sheet are battery sheets, the length of the active slurry layer of the negative electrode sheet and the length of the active slurry layer of the positive electrode sheet satisfy:

[0038] G1'=G1"+p,G n-1 '=G n-1 ”+q,G n '=G n ”+r;

[0039] Among them, G1', G n-1 ', G n ' respectively represent the length of the first active paste layer of the negative electrode sheet, the length of the n-1th active paste layer, and the length of the nth active paste layer; G1", G n-1 ”, G n " respectively represent the length of the first active slurry layer of the positive electrode sheet, the length of the n-1th active slurry layer, and the length of the nth active slurry layer; n≥2; 10mm≤p≤30mm; 2mm≤q≤5mm; 10mm≤r≤30mm.

[0040] By limiting the length relationship of the active slurry layer in the negative electrode sheet and the positive electrode sheet, the preparation requirements of the wound battery cell can be met. During the preparation process, the negative electrode can be wound in a manner of first straightening and then bending, and the positive electrode can be wound in a manner of first bending and then straightening.

[0041] In one possible design, the battery cell is a wound battery cell, and one circle of the wound battery cell corresponds to one pole ear;

[0042] When the lengths of each section of the active slurry layer are equal and the lengths of each section of the non-conductive slurry layer are equal, the length of the active slurry layer is equal to 2 / L, and the length of the non-conductive slurry layer is less than 0 and less than or equal to 20 mm; wherein L represents the circumference of the winding needle of the wound battery cell.

[0043] In a possible design, the length of the non-conductive paste layer is less than 1 and less than or equal to 5 mm.

[0044] For wound cells, the problem of cold-pressed breakage of the pole piece during the preparation of the cell can be effectively prevented by limiting the length of the active slurry layer 12 and the length of the non-conductive slurry layer 13. Applying such cells to batteries can reduce battery polarization, improve rate performance, cycle performance and low-temperature performance, and reduce the risk of lithium deposition at the corners of wound batteries, thereby improving battery safety.

[0045] In a possible design, the battery cell is a laminated battery cell, the lengths of the active slurry layers of each segment are equal, the lengths of the non-conductive slurry layers of each segment are equal; one pole ear corresponds to one segment of the active slurry layer;

[0046] The electrode tabs include a first electrode tab and a second electrode tab, and the first electrode tab and the second electrode tab are alternately arranged at the position where the current collector is coated with an active slurry layer; the active slurry layer has a first side and a second side, the first electrode tab is arranged on the first side of a section of the active slurry layer, and the second electrode tab is arranged on the second side of the next section of the active slurry layer.

[0047] By limiting the position of the tabs, the use requirements of different laminated battery cells can be met.

[0048] In a possible design, the length of the non-conductive paste layer is greater than 0.5 mm and less than or equal to 3.5 mm.

[0049] For stacked battery cells, the length of the non-conductive slurry layer is limited to reduce battery polarization and improve rate performance, cycle performance and low-temperature performance.

[0050] According to a third aspect of the present application, the present application also provides a battery, which includes the above-mentioned battery cell.

[0051] According to a fourth aspect of the present application, the present application also provides a battery module, comprising the battery of the present application.

[0052] According to the fifth aspect of the present application, the present application also provides a battery pack, comprising the battery module of the present application.

[0053] According to the sixth aspect of the present application, the present application also provides an electrical device, including the battery pack of the present application.

[0054] Advantages of this application:

[0055] The present application discloses a battery pole sheet that alternately coats an active slurry layer and a non-conductive slurry layer on the surface of a current collector, which can ensure the uniformity of the extension of the battery pole sheet in the area coated with the active slurry layer and the area coated with the non-conductive slurry layer, thereby solving the problem of cold-pressed fracture of the battery pole sheet. Compared with a battery pole sheet that is continuously coated with an active slurry layer, such a battery pole sheet can reduce battery polarization, improve rate performance, cycle performance and low-temperature performance, and can also reduce the risk of lithium deposition at the corners of the wound battery, thereby improving the safety performance of the battery.

[0056] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A schematic structural diagram of a battery electrode provided in the present application in a first embodiment;

[0058] Figure 2 A schematic structural diagram of a battery electrode provided in the present application in a second embodiment;

[0059] Figure 3 A schematic structural diagram of a battery electrode provided in the present application in a third embodiment;

[0060] Figure 4 A schematic diagram of the structure of a battery electrode provided in the present application when forming a wound battery cell.

[0061] Reference numerals:

[0062] 1-Battery pole piece;

[0063] 11-Current collector;

[0064] 12-active slurry layer;

[0065] 13- non-conductive slurry layer;

[0066] 14-ear;

[0067] 141- first pole lug;

[0068] 142-second pole lug.

[0069] θ-the center angle of the semicircle formed by the non-conductive slurry layer at the corner of the wound battery cell;

[0070] θ1-angle of the first coating area of ​​the non-conductive slurry layer at the corner of the wound battery cell;

[0071] θ2-angle of the second coating area of ​​the non-conductive slurry layer at the corner of the wound battery cell;

[0072] L- circumference of the winding needle;

[0073] b- The length reserved for the head of the battery pole piece when forming a wound battery cell;

[0074] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application. DETAILED DESCRIPTION

[0075] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0076] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0077] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0078] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0079] It should be noted that the directional words such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described at the angles shown in the accompanying drawings and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0080] With the rapid development of new energy vehicles, the installed capacity of power batteries has also increased year by year, and a large number of batteries have been used in electric vehicles. According to the shell material and shape of the battery, it can be divided into square aluminum shell batteries, soft pack batteries and cylindrical batteries. Among them, square aluminum shell batteries are the most widely used, accounting for more than two-thirds of the installed capacity of the three. The internal cell structure of square aluminum shell batteries is mainly divided into two types: stacked type and winding type. Among them, the winding structure technology is more mature, with fast production speed and high efficiency, and is widely used in square aluminum shell batteries.

[0081] Traditional square wound pole pieces use continuous coating to evenly coat the slurry on the current collector. After such pole pieces are wound and hot-pressed, lithium is easily deposited at the corners during battery use. Related technologies also use intermittent coating to prepare square wound pole pieces. The specific method is as follows: intermittently coat the battery slurry on both sides of the current collector to form two or more slurry coating areas that are spaced in sequence along the length of the current collector, and leave a blank area at the end of each slurry coating area where the battery slurry is not coated; after the intermittent coating on both sides is completed, the current collector coated with more than two slurry coating areas is rolled and punched to obtain the required square wound battery pole piece.

[0082] Such square wound pole pieces generally reserve blank gaps at the corners of the wound battery cell, which can overcome the problems of increased polarization and lithium deposition at the corners during battery use. However, pole pieces using this intermittent coating method may break during cold pressing due to uneven extension of the coated and uncoated areas.

[0083] In order to solve the problem of the existing square wound pole piece being broken during the cold pressing process due to the uneven extension of the coated area and the uncoated area, the applicant has found that some material can be filled in the blank area where the battery slurry is not coated to ensure the uniform extension of the pole piece in the area coated with the battery slurry and the area filled with some material, so as to overcome the problem of the pole piece being broken during the cold pressing.

[0084] Based on the above considerations, in order to solve the problem of cold-pressing breakage of the existing square wound pole piece due to uneven extension of the coated area and the uncoated area during the cold pressing process, the inventors have designed a battery pole piece after in-depth research. The battery pole piece includes a current collector, an active slurry layer, a non-conductive slurry layer and a pole ear. Along the length direction of the current collector, multiple sections of active slurry layer and multiple sections of non-conductive slurry layer are alternately coated on the current collector, and the pole ear is electrically connected to the current collector.

[0085] Such a battery pole piece alternately coats an active slurry layer and a non-conductive slurry layer on the surface of the current collector, which can ensure the uniformity of the extension of the battery pole piece in the area coated with the active slurry layer and the area coated with the non-conductive slurry layer, thereby solving the problem of cold-pressed fracture of the battery pole piece. Compared with a battery pole piece with a continuous coating of an active slurry layer, such a battery pole piece can reduce battery polarization, improve rate performance, cycle performance and low-temperature performance, and can also reduce the risk of lithium plating at the corners of the wound battery, thereby improving the safety performance of the battery.

[0086] The battery pole piece disclosed in the embodiment of the present application can be used, but is not limited to, in wound-type battery cells, laminated battery cells and other battery cells, and can avoid the problem of pole piece cold pressure breaking during the preparation process of the battery cell. Applying the battery cell prepared using the battery pole piece of the present application to the battery can reduce battery polarization, improve rate performance, cycle performance and low-temperature performance, and can also reduce the risk of lithium plating at the corners of the wound battery, improving the safety performance of the battery. The battery prepared using the battery pole piece disclosed in the embodiment of the present application can also be used to prepare a battery module, and the prepared battery module can be further prepared into a battery pack, and the prepared battery pack can be further prepared into an electrical device.

[0087] According to some embodiments of the present application, Figure 1 As shown, Figure 1 This is a schematic diagram of a battery electrode according to some embodiments of the present application. The present application provides a battery electrode, wherein the battery electrode 1 includes a current collector 11, an active slurry layer 12, a non-conductive slurry layer 13 and a pole ear 14. Along the length direction of the current collector 11, multiple sections of the active slurry layer 12 and multiple sections of the non-conductive slurry layer 13 are alternately coated on the current collector 11, and the pole ear 14 is electrically connected to the current collector 11.

[0088] The current collector 11 refers to a structure or part for collecting current. Its main function is to collect the current generated by the active material of the battery so as to form a larger current for external output. The current collector 11 should be in full contact with the active material, and the internal resistance should be as small as possible. The current collector 11 can be a positive electrode current collector or a negative electrode current collector. The current collector 11 can use any known current collector. Examples of the current collector include, but are not limited to, metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel.

[0089] Active slurry layer 12, active slurry layer 12 can be one or more layers, each layer of the multi-layer active slurry layer 12 can contain the same or different active materials, and the active material is any material that can reversibly embed and deintercalate metal ions such as lithium ions. If the prepared battery pole piece is a positive pole piece, the active material is a positive active material, and the type of positive active material is not particularly limited, as long as it can electrochemically absorb and release metal ions (for example, lithium ions). In some embodiments, the positive active material is a material containing lithium and at least one transition metal. Examples of positive active materials may include, but are not limited to, lithium transition metal composite oxides and lithium-containing transition metal phosphate compounds. If the prepared battery pole piece is a negative pole piece, the active material is a negative active material, and the negative active material is not particularly limited, as long as it can reversibly absorb and release lithium ions. Examples of negative active materials may include, but are not limited to, carbon materials such as natural graphite and artificial graphite; silicon-based materials such as pure silicon, silicon oxide, silicon-carbon composites, and alloys of silicon and metal elements.

[0090] The non-conductive slurry layer 13 is made of a material that has no conductive properties, and serves to separate the sections of the active slurry layer 12, which can effectively prevent the polarization of the battery from increasing and the battery performance from deteriorating, reduce the risk of lithium plating at the corners of the wound battery, and improve the safety performance of the battery. At the same time, it can make the part coated with the non-conductive slurry layer have a certain ductility, preventing the battery electrode 1 from breaking from the part that is not coated with the active slurry layer 12 during the winding process.

[0091] The tabs 14 are metal conductors that lead the positive and negative electrodes out of the battery cell.

[0092] By alternately coating the active slurry layer 12 and the non-conductive slurry layer 13 on the surface of the current collector 11, the uniformity of the extension of the battery pole piece in the area coated with the active slurry layer 12 and the area coated with the non-conductive slurry layer 13 can be ensured, thereby solving the problem of cold-pressed fracture of the battery pole piece. In addition, compared with the battery pole piece 1 that is continuously coated with the active slurry layer 12, the battery pole piece 1 of the present application intermittently coats the active slurry layer 12 on the surface of the current collector 11, which can reduce the polarization of the battery, solve the problem of increased polarization of the battery caused by continuous coating of the slurry on the current collector 11, improve the battery rate performance, cycle performance and low temperature performance, and reduce the risk of lithium plating at the corners of the wound battery, thereby improving the safety performance of the battery.

[0093] According to some specific embodiments of the present application, the thickness D1 of the active paste layer 12 and the thickness D2 of the non-conductive paste layer 13 satisfy: 0<D2≤D1.

[0094] Thickness refers to the vertical distance between the upper and lower surfaces of the slurry layer.

[0095] By limiting the thickness D2 of the non-conductive slurry layer 13 to be greater than zero and less than or equal to the thickness D1 of the active slurry layer 12, the portion coated with the non-conductive slurry layer can have a certain degree of ductility, thereby preventing the battery pole piece 1 from breaking from the portion not coated with the active slurry layer 12 during the curling process. If the thickness D2 of the non-conductive slurry layer 13 is greater than the thickness D1 of the active slurry layer 12, a gap will be generated when the battery pole piece 1 cooperates with other pole pieces during the preparation of the battery cell, affecting the assembly of the battery cell.

[0096] According to some embodiments of the present application, the lengths of the active slurry layers 12 are different or equal. The lengths of the non-conductive slurry layers 13 are different or equal.

[0097] The length of the active slurry layer 12 and the length of the non-conductive slurry layer 13 are the vertical distances between the left and right ends of the slurry layer along the length direction of the current collector 11. The lengths of each section of the active slurry layer 12 can be equal, or they can increase or decrease regularly, or they can be irregularly unequal. The lengths of the non-conductive slurry layer 13 can be equal, or they can increase or decrease regularly, or they can be irregularly unequal. The specific lengths need to be determined according to the winding or stacking method of the actual battery cell design.

[0098] In some specific embodiments, when the lengths of the active slurry layers 12 are equal, the lengths of the non-conductive slurry layers 13 are also equal. Such a battery electrode sheet 1 can be used to prepare a wound or laminated battery cell.

[0099] In some other specific embodiments, when the length of each section of the active slurry layer 12 increases or decreases regularly, the length of each section of the non-conductive slurry layer 13 also increases or decreases regularly.

[0100] By limiting the length of each section of the active slurry layer 12 and the length of each section of the non-conductive slurry layer 13 , the prepared battery pole piece 1 has good applicability in both wound-type battery cells and laminated battery cells.

[0101] According to some embodiments of the present application, the electrode tab 14 is connected to the position where the current collector 11 is coated with the active slurry layer 12 , and one electrode tab 14 corresponds to one or two sections of the active slurry layer 12 .

[0102] The tab 14 is connected to the position of the current collector 11 coated with the active slurry layer 12 , which means that a portion of the area not coated with the active slurry layer 12 is reserved in the area coated with the active slurry layer 12 for installing the tab 14 .

[0103] One pole tab 14 corresponds to two sections of active slurry layer 12, which means that along the length direction of the current collector 11, the pole tab 14 is arranged on the active slurry layer 12 at intervals, and the installation position of the pole tab 14 on the active slurry layer 12 can be located on the left or right side of the active slurry layer 12. Such a battery pole sheet 1 can be suitable for the case of one pole tab per winding cell. In some specific embodiments, such as Figure 1 As shown, the tab 14 is located on the left side of the active slurry layer 12 .

[0104] One pole ear 14 corresponds to one section of active slurry layer 12, which means that one pole ear 14 is arranged on each section of active slurry layer 12, and the arrangement position of the pole ear 14 on each section of active slurry layer 12 can be located on the left side of the active slurry layer 12, can be located on the right side of the active slurry layer 12, or one pole ear 14 can be arranged on the left side of one section of active slurry layer 12, and the next pole ear 14 can be arranged on the right side of the next section of active slurry layer 12, and they can be arranged alternately in sequence. Such a battery pole sheet 1 can be used in both laminated battery cells and wound battery cells. In some specific embodiments, such as Figure 2 In the battery pole piece 1 shown, the pole lug 14 is arranged at the left side of the active slurry layer 12 in each section. Such a battery pole piece 1 is suitable for the case where one pole lug is arranged in one circle of a wound battery cell. Figure 3 In the battery pole piece 1 shown, one pole ear 14 is arranged on the left side of a section of active slurry layer 12, and the next pole ear 14 is arranged on the right side of the next section of active slurry layer 12, and they are arranged alternately in sequence. Such a battery pole piece 1 can be used in both laminated battery cells and wound battery cells.

[0105] By connecting the pole ear 14 to the position where the active slurry layer 12 is coated on the current collector 11, it can be ensured that the pole ear 14 is not affected by the winding process of the battery pole piece 1. By corresponding one pole ear 14 to one or two sections of the active slurry layer 12, the preparation requirements of different battery cells can be met, thereby improving the applicability of the battery pole piece.

[0106] According to some embodiments of the present application, the active slurry layer 12 and the non-conductive slurry layer 13 are coated on the current collector 11 by an intermittent coating method.

[0107] The intermittent coating method refers to coating the slurry on the current collector 11 with intermittent separation in the middle process. Specifically in this application, the active slurry layer 12 is coated on the current collector 11 with intermittent separation in the middle process, and the intermittent separation position is coated with a non-conductive slurry layer 13.

[0108] By adopting an intermittent coating method, the active slurry layer 12 and the non-conductive slurry layer 13 can be effectively coated on the current collector 11, so as to avoid the problem of increased polarization of the battery, improve the battery rate performance, cycle performance and low temperature performance, reduce the risk of lithium plating at the corners of the wound battery, and improve the safety performance of the battery.

[0109] According to some embodiments of the present application, the active slurry layer 12 and the non-conductive slurry layer 13 are coated on both sides of the current collector 11 .

[0110] The active slurry layer 12 and the non-conductive slurry layer 13 are coated on both sides of the current collector 11, which means that the active slurry layer 12 and the non-conductive slurry layer 13 are coated on both the front and back sides of the current collector 11, and the thickness, length and other technical indicators of the active slurry layer 12 and the non-conductive slurry layer 13 coated on the front and back sides of the current collector 11 can be the same or different, and can be adjusted in time according to actual design needs. In some specific embodiments, the thickness and length of the active slurry layer 12 and the non-conductive slurry layer 13 coated on the front and back sides of the current collector 11 are consistent, and the active slurry layer 12 on the front and back sides of the current collector 11 is directly overlapped, and the non-conductive slurry layer 13 is directly overlapped.

[0111] By coating the active slurry layer 12 and the non-conductive slurry layer 13 on both sides of the current collector 11, it is beneficial to reduce the polarization effect of the battery and improve the consistency, safety, cycle life, rate performance and low temperature performance of the battery.

[0112] According to some embodiments of the present application, the non-conductive paste in the non-conductive paste layer 13 is prepared from the following raw materials in parts by weight: 80-95 parts of non-conductive nanomaterials, 5-20 parts of binders, and 43-150 parts of solvents.

[0113] The non-conductive nanomaterial makes the non-conductive slurry layer 13 have non-conductive properties. In order to adapt to the application environment and use conditions of the battery, the non-conductive nanomaterial has certain requirements in terms of resistivity, acid and alkali resistance, strength, hardness, elongation, solubility, and thermal stability. In some specific embodiments, the non-conductive nanomaterial must meet one or more of the following properties: (1) resistivity > 102Ω / cm; (2) acid and alkali resistance; (3) hardness ≥ 3 Mohs; (4) elongation ≤ 1%; (5) insoluble in water or organic solvents; (6) thermal stability > 850°C.

[0114] In some specific embodiments, the non-conductive nanomaterial can be selected from one or more of Al2O3, ZrO2, SiO2, CaSiO3, Al4C3, SiC, B4C, AlN, BN, and CaCO3.

[0115] The solvent plays a role in dispersing the non-conductive nanomaterials. The solvent may be an organic solvent, which may be selected from ketone organic solvents, alcohol organic solvents, ether organic solvents, etc. In some specific embodiments, the solvent is N-methylpyrrolidone.

[0116] The binder is a guarantee of the direct bonding strength between the non-conductive nanomaterial and the solvent, which is conducive to the implementation of the coating process. In some specific embodiments, the binder includes at least one of polyvinylidene fluoride PVDF, polytetrafluoroethylene PTFE, sodium carboxymethyl cellulose CMC, styrene-butadiene rubber SBR, nitrile rubber, polyurethane, fluorinated rubber, polyvinyl alcohol PVA, and sodium polyacrylate.

[0117] By limiting the components of the non-conductive slurry in the non-conductive slurry layer 13 and the ratio between the components, the non-conductive slurry layer 13 has properties such as resistivity, acid and alkali resistance, hardness, elongation, solubility, and thermal stability that are adapted to the application environment and use conditions of the battery, so that the battery electrode 1 will not have the problem of cold-pressing breakage at the non-conductive slurry layer 13.

[0118] According to some embodiments of the present application, the present application provides a battery cell, which may be a wound battery cell or a stacked battery cell. The battery cell includes a negative electrode sheet and a positive electrode sheet that cooperate with each other, and one or both of the negative electrode sheet and the positive electrode sheet are the battery electrode sheets 1 disclosed in the present application. Such a battery cell has the problem of cold-pressed electrode sheet breakage during the preparation process. Applying such a battery cell to a battery can reduce battery polarization, improve rate performance, cycle performance, and low-temperature performance, and can also reduce the risk of lithium plating at the corners of a wound battery, thereby improving the safety performance of the battery.

[0119] According to some embodiments of the present application, the battery cell is a wound battery cell, which is formed by winding a negative electrode sheet, a positive electrode sheet, and a separation layer between the negative electrode sheet and the positive electrode sheet. Figure 1 and Figure 4 As shown, Figure 4 It is a schematic diagram of the winding of the battery electrode 1 in the battery cell, Figure 1 Schematic diagram of the battery electrode 1 when it is not wound, wherein the lengths of the active slurry layers 12 of each section are different, the lengths of the non-conductive slurry layers 13 of each section are different, and along the length direction of the current collector 11, the lengths of the active slurry layers 12 increase successively, and the lengths of the non-conductive slurry layers 13 increase successively, and the lengths of the active slurry layers 12 of each section satisfy the following formula:

[0120] G1=L / 2-b+(H1-K1) / 2,

[0121] G n-1 =L / 2+(H n-2 -K n-2 ) / 2+(H n-1 -K n-1) / 2,

[0122] G n =L / 2+(H n-1 -K n-1 ) / 2;

[0123] Among them, G1, G n-1 , G n Respectively represent the length of the first active slurry layer 12, the length of the n-1th active slurry layer 12, and the length of the nth active slurry layer 12; n≥2;

[0124] L represents the circumference of the winding needle of the wound battery cell;

[0125] b represents the length reserved for the head of the battery pole piece 1 when forming a wound battery cell; b satisfies: 10mm≤b≤30mm;

[0126] H1, H n-1 , H n-2 They respectively represent the arc length of the semicircle formed at the first corner, the arc length of the semicircle formed at the n-1th corner, and the arc length of the semicircle formed at the n-2th corner from the inside to the outside when the battery electrode 1 forms a wound battery cell;

[0127] K1, K n-1 , K n-2 They respectively represent the length of the non-conductive paste layer 13 formed at the first corner from the inside to the outside of the battery electrode 1 when forming a wound battery cell, the length of the n-1th section of the non-conductive paste layer 13, and the length of the n-2th section of the non-conductive paste layer 13.

[0128] The wound battery cell is formed by winding a negative electrode sheet, a positive electrode sheet and an isolation layer between the negative electrode sheet and the positive electrode sheet. In actual production, the winding of the electrode group is completed by a winding needle on an automatic winding machine.

[0129] G1, G n-1 , G n G represents the length of the first active slurry layer 12, the length of the n-1th active slurry layer 12, and the length of the nth active slurry layer 12, respectively. n It means that the outermost circle of the battery electrode 1 ends before the corner; n can be selected from 2, 4, 6, 8, 10, 30 or 50, etc., and of course it can also be other values ​​within the above range, which is not limited here.

[0130] The battery pole piece 1 has a certain length reserved at the head when forming a wound battery cell in order to maintain a certain capacity of the battery cell. The length b reserved at the head of the battery pole piece 1 when forming a wound battery cell can be selected from 10mm, 15mm, 20mm, 25mm or 30mm, etc., and of course can also be other values ​​within the above range, which is not limited here.

[0131] By using a formula to define the length of each section of the active slurry layer 12, and along the length direction of the current collector 11, the length of the active slurry layer 12 increases successively, and the length of the non-conductive slurry layer 13 increases successively, so that the active slurry layer 12 and the non-conductive slurry layer 13 are located at the turning point of the battery cell during winding, thereby reducing the polarization effect at the turning point and enhancing the improvement effect on the battery performance.

[0132] According to some embodiments of the present application, a center angle θ of a semicircular arc formed by the non-conductive slurry layer 13 at a corner of the wound battery cell satisfies: 30°≤θ≤90°.

[0133] When the battery electrode 1 is wound to form a wound battery cell, the active slurry layer 12 and the non-conductive slurry layer 13 at the corners will be extended to meet the winding requirements. The center angle θ of the semicircular arc formed by the non-conductive slurry layer 13 at the corner of the wound battery cell can be selected from 30°, 40°, 50°, 60°, 70°, 80° or 90°, etc., and of course it can also be other values ​​within the above range, which is not limited here.

[0134] By limiting the range of the center angle θ of the semicircular arc formed by the non-conductive slurry layer 13 at the corner of the wound battery cell, it is ensured that the non-conductive slurry layer 13 is completely located at the corner of the battery cell during winding, thereby further reducing the polarization effect at the corner and enhancing the improvement effect on battery performance. Under the condition that the center angle θ of the semicircular arc formed by the non-conductive slurry layer 13 at the corner of the wound battery cell is limited to 30°≤θ≤90°, it can be obtained that the length K of the non-conductive slurry layer 13 at the corner of the wound battery cell is n Satisfaction: H n / 6≤K n =θ*H n / 180≤H n / 2. It should be noted that H n It represents the length of the semicircular arc formed from the inside to the outside at the nth corner when the battery pole piece forms a wound battery cell. The angle is used to define the proportion of the coating area length to the total arc length. Then the coating length of the non-conductive slurry at the corner is H. n / 6≤K n ≤H n / 2, or H n / 6≤K n =θ*H n / 180≤H n / 2.

[0135] According to some embodiments of the present application, the semicircular arc length H formed at the nth corner of the battery electrode sheet 1 when forming a wound battery cell is n =Π*d n / 2, where d nis the diameter of the semicircle formed by the battery pole piece at the nth corner when forming a wound battery cell;

[0136] When n=1, d1=(mS+2S+2A) / 1000; when n≥2, d n =(mS+2S+2A+(2S+A+C)*(n-1)) / 1000; wherein, m is the number of isolation layers; S is the thickness of the isolation layer; A is the thickness of the negative electrode plate; and C is the thickness of the positive electrode plate.

[0137] The wound battery cell is formed by winding a negative electrode sheet, a positive electrode sheet and an isolation layer separated from the negative electrode sheet and the positive electrode sheet. The isolation layer can be one layer or multiple layers. The isolation layer generally includes an isolation film and an isolation film coating coated on the isolation film. The thickness of the isolation layer refers to the sum of the thickness of the isolation film and the isolation film coating.

[0138] d n The unit of is mm, and the units of A, S and C are all μm.

[0139] The semicircle diameter d formed by the battery pole piece 1 at the nth corner when forming the wound battery cell n The value of can be used to calculate the length H of the semicircular arc formed by the battery electrode 1 at the nth corner when forming a wound battery cell. n The diameter d of the semicircle formed by the battery pole piece at the nth corner when forming a wound battery cell n It can be obtained based on the values ​​of the thickness S of the isolation layer, the thickness A of the negative electrode sheet, and the thickness C of the positive electrode sheet.

[0140] According to some embodiments of the present application, when both the negative electrode sheet and the positive electrode sheet are battery electrode sheets 1, the length of the active slurry layer 12 of the negative electrode sheet and the length of the active slurry layer 12 of the positive electrode sheet satisfy:

[0141] G1'=G1"+p,G n-1 '=G n-1 ”+q,G n '=G n ”+r;

[0142] Among them, G1', G n-1 ', G n ' respectively represent the length of the first active paste layer of the negative electrode sheet, the length of the n-1th active paste layer, and the length of the nth active paste layer; G1", G n-1 ”, G n " respectively represent the length of the first active slurry layer of the positive electrode sheet, the length of the n-1th active slurry layer, and the length of the nth active slurry layer; n≥2; 10mm≤p≤30mm; 2mm≤q≤5mm; 10mm≤r≤30mm.

[0143] p represents the length of the first coil negative electrode lead-in portion when forming a wound cell. q represents the length of the first and last negative electrodes more than the positive electrodes. r represents the length of the last coil negative electrode lead-in portion when forming a wound cell.

[0144] By limiting the length relationship of the active slurry layer 12 in the negative electrode sheet and the positive electrode sheet, the preparation requirements of the wound battery cell can be met. During the preparation process, the negative electrode can be wound in a manner of first straightening and then bending, and the positive electrode can be wound in a manner of first bending and then straightening.

[0145] According to some embodiments of the present application, the battery cell is a wound battery cell, and one circle of the wound battery cell corresponds to one pole ear 14 .

[0146] When the lengths of the active slurry layers 12 and the non-conductive slurry layers 13 are equal, the length of the active slurry layer 12 is equal to 2 / L, and the length of the non-conductive slurry layer 13 is less than 0 and less than or equal to 20 mm. Wherein, L represents the circumference of the winding needle of the wound battery cell.

[0147] One circle of the wound battery cell corresponds to one pole lug 14 , which means that the wound battery cell is wound in one circle, and one pole lug 14 is arranged on one circle.

[0148] The length of the non-conductive slurry layer 13 can be selected from 1 mm, 5 mm, 10 mm, 15 mm or 20 mm, etc., and of course it can also be other values ​​within the above range, which is not limited here. In some specific embodiments, the length of the non-conductive slurry layer 13 is less than 1 mm and less than or equal to 5 mm, and can be specifically selected from 2 mm, 3 mm, 4 mm, or 5 mm, etc., and of course it can also be other values ​​within the above range, which is not limited here.

[0149] For wound cells, the problem of cold-pressed breakage of the pole piece during the preparation of the cell can be effectively prevented by limiting the length of the active slurry layer 12 and the length of the non-conductive slurry layer 13. Applying such cells to batteries can reduce battery polarization, improve rate performance, cycle performance and low-temperature performance, and reduce the risk of lithium deposition at the corners of wound batteries, thereby improving battery safety.

[0150] According to some embodiments of the present application, the battery cell is a laminated battery cell, the lengths of the active slurry layers 12 are equal, and the lengths of the non-conductive slurry layers 13 are equal. One tab 14 corresponds to one section of the active slurry layer 12 .

[0151] like Figure 3As shown, the pole tab 14 includes a first pole tab 141 and a second pole tab 142, and the first pole tab 141 and the second pole tab 142 are alternately arranged at the position where the current collector 11 is coated with the active slurry layer 12. The active slurry layer 12 has a first side and a second side, the first pole tab 141 is arranged on the first side of a section of the active slurry layer 12, and the second pole tab 142 is arranged on the second side of the next section of the active slurry layer 12.

[0152] The first side may be the left side or the right side of the active slurry layer 12, and the corresponding second side may be the right side or the left side of the active slurry layer 12. The first pole ear 141 is arranged on the first side of a section of the active slurry layer 12, and the second pole ear 142 is arranged on the second side of the next section of the active slurry layer 12, which means that if the first pole ear 141 is arranged on the first side of the first section of the active slurry layer 12, then the second pole ear 142 is arranged on the second side of the second section of the active slurry layer 12, the first pole ear 141 is arranged on the first side of the third section of the active slurry layer 12, and the second pole ear 142 is arranged on the second side of the fourth section of the active slurry layer 12, and they are arranged alternately in sequence.

[0153] By limiting the position of the pole ear 14, the use requirements of different laminated battery cells can be met.

[0154] According to some embodiments of the present application, the length of the non-conductive paste layer 13 is greater than 0.5 mm and less than or equal to 3.5 mm.

[0155] The length of the non-conductive slurry layer 13 can be selected from 1mm, 1.5mm, 2mm, 2.5mm, 3mm or 3.5mm, etc., and can also be other values ​​within the above range, which is not limited here. Accordingly, the length of the active slurry layer 12 is determined according to actual conditions.

[0156] For laminated cells, the length of the non-conductive slurry layer 13 is limited to reduce battery polarization and improve rate performance, cycle performance and low-temperature performance.

[0157] According to some embodiments of the present application, Figure 1 As shown, the present application provides a battery pole piece 1, which is a positive electrode pole piece of a battery. An active slurry and a non-conductive slurry are intermittently coated on both sides of a current collector 11 to form an active slurry layer 12 and a non-conductive slurry layer 13, wherein a thickness D1 of the active slurry layer 12 is equal to a thickness D2 of the non-conductive slurry layer 13.

[0158] According to some embodiments of the present application, Figure 1 and Figure 3As shown, the present application provides a battery cell, which is a wound battery cell, and its positive electrode plate adopts the battery plate 1 of the present application, and the length of the active slurry layer 12 of each section in the battery plate 1 is not equal, and the length of the non-conductive slurry layer 13 of each section is also not equal. The length of the non-conductive slurry layer 13 can be determined according to the diameter size of the arc of the wound battery cell, and the negative electrode is wound in a manner of first straightening and then bending, and the positive electrode is wound in a manner of first bending and then straightening, and the innermost circle has 6 layers of isolation layers. Then, the diameter of the semicircle formed at the first corner of the innermost circle of the positive electrode of the wound battery cell is d1=(6S+2S+2A) / 1000, and the diameter of the semicircle formed at the second corner is d2=((6S+2S+2A+(2S+A+C)*1)) / 1000, and the diameter of the semicircle formed at the nth corner is: d n =((6S+2S+2A+(2S+A+C)*(n-1)) / 1000 (unit: mm), where S is the thickness of the isolation layer, A is the thickness of the negative electrode sheet, and C is the thickness of the positive electrode sheet (unit: μm). According to the above algorithm, the length of the semicircular arc formed at the first corner of the innermost circle of the positive electrode of the wound battery cell is H1=Π*d1 / 2, and the length of the semicircular arc formed at the second corner is H2=Π*d2 / 2, then the length of the semicircular arc formed at the nth corner is: H n =Π*d n / 2. Figure 4 As shown, represented by θ1 and θ2, where θ1=θ2, and 30°≤θ=θ1+θ2≤90°, it can be concluded that the length of the non-conductive paste layer 13 at the first corner of the innermost circle is K1 in the range of H1 / 6≤K1≤H1 / 2, the length of the non-conductive paste layer 13 at the second corner is K2 in the range of H2 / 6≤K2≤H2 / 2, and the length of the non-conductive paste layer 13 at the nth corner is K n The range is H n / 6≤K n ≤H n / 2. The length of each section of the active slurry layer 12 is calculated as follows: the circumference of the winding needle L (unit: mm), then the length of the first section of the active slurry layer 12 is: G1 = L / 2-10 + (H1-K1) / 2 (10 mm is reserved for the head), the length of the second section of the active slurry layer 12 is: G2 = L / 2 + (H1-K1) / 2 + (H2-K2) / 2, the length of the n-1th section of the active slurry layer 12 is: G n-1 =L / 2+(H n-2 -K n-2 ) / 2+(H n-1 -K n-1 ) / 2, the length of the nth active slurry layer 12 is: G n =L / 2+(H n-1 -K n-1 ) / 2 (the outermost circle of the positive electrode ends before the corner).

[0159] The technical solution of the present application will be compared and explained below through embodiments and comparative examples.

[0160] Example 1

[0161] It is planned to prepare a wound battery cell, in which the positive electrode sheet, the negative electrode sheet and the isolation layer between the negative electrode sheet and the positive electrode sheet are wound by an automatic winding machine in the manner of straightening the negative electrode first and bending it later, and bending the positive electrode first and straightening it later to form a wound battery cell, wherein the circumference L of the winding needle on the winding machine is 344mm, and the innermost circle of the wound battery cell has 6 isolation layers, and the thickness S of each isolation layer is 12μm. The central angle θ of the semicircular arc formed by the non-conductive slurry layer 13 at the corner in the wound battery cell is specifically 60°.

[0162] The preparation method of the negative electrode sheet is as follows:

[0163] The negative electrode active material is coated on a copper foil with a length of 350 mm and a thickness of 6 μm by continuous coating, one out of two, leaving tabs on both sides, and the total coating area length is 309 mm to obtain a negative electrode sheet. The thickness A of the negative electrode sheet is equal to 125 μm.

[0164] Based on the properties of the wound battery cell to be prepared and the properties of the negative electrode sheet and the separator used, a positive electrode sheet is prepared by the following method:

[0165] 475 kg of positive electrode active material LiFePO4, 10 kg of conductive agent, 15 kg of binder, and 300 kg of N-methylpyrrolidone NMP are mixed, and then stirred in a vacuum mixer to obtain a uniform positive electrode active slurry; 95 kg of nano alumina powder Al2O3, 5 kg of binder polyvinylidene fluoride PVDF, and 43 kg of N-methylpyrrolidone NMP are mixed, and then stirred in a vacuum mixer to obtain a uniform non-conductive slurry.

[0166] The obtained positive electrode active slurry and non-conductive slurry are coated on the current collector 11 (aluminum foil) with a length of 347mm and a thickness of 15μm. The coating is carried out by extrusion coating, one out of two, leaving pole ears on both sides of the aluminum foil, and the total coating area length is 296mm. After coating and drying, an active slurry layer 12 and a non-conductive slurry layer 13 are formed on the aluminum foil, thereby obtaining a positive electrode sheet. Among them, the thickness C of the positive electrode sheet is equal to 186μm, the thickness D1 of the active slurry layer 12 is equal to the thickness D2 of the non-conductive slurry layer 13, and the lengths of each section of the active slurry layer 12 and each section of the non-conductive slurry layer 13 are not equal, according to the following formula: G1 = L / 2-10+(H1-K1) / 2, G n-1 =L / 2+(H n-2 -K n-2 ) / 2+(H n-1 -K n-1) / 2,G n =L / 2+(H n-1 -K n-1 ) / 2, where n is 30, K n =θ*H n / 180, and the length K of the non-conductive slurry layer (13) formed at each corner of each section of the active slurry layer 12 and the positive electrode sheet when forming the wound battery cell is calculated. n The length of the non-conductive slurry layer 13 of the positive electrode sheet when it is not wound is calculated based on the relationship between the active slurry layer 12 and the coating area length of 296 mm and the elongation rate of the positive electrode sheet of 1%.

[0167] The obtained positive electrode sheet was cold pressed, and the compaction density was 2.65g / cm 3 , record the number of cold-pressed broken strips of 1000m pole pieces, and the recorded results are shown in Table 1.

[0168] Example 2

[0169] In this embodiment, the preparation method of the positive electrode sheet is different from that of Embodiment 1 in the following aspects, and the rest is the same as that of Embodiment 1:

[0170] 475 kg of positive electrode active material LiFePO4, 10 kg of conductive agent, 15 kg of binder, and 300 kg of N-methylpyrrolidone NMP are mixed, and then stirred in a vacuum mixer to obtain a uniform positive electrode active slurry; 87.5 kg of nano silicon carbide powder SiC, 12.5 kg of binder polyvinylidene fluoride PVDF, and 82 kg of N-methylpyrrolidone NMP are mixed, and then stirred in a vacuum mixer to obtain a uniform non-conductive slurry.

[0171] Take the above positive electrode active material and non-conductive material slurry, and start coating on an aluminum foil with a length of 347 mm and a thickness of 15 μm. The coating adopts an extrusion coating method, one out of two, leaving pole ears on both sides of the aluminum foil, and the total coating area length is 296 mm. After coating and drying, an active slurry layer 12 and a non-conductive slurry layer 13 of equal thickness are formed on the aluminum foil, thereby obtaining a positive electrode sheet. The length of the active slurry layer 12 and the length of the non-conductive slurry layer 13 in the positive electrode sheet are calculated in the same way as in Example 1.

[0172] The obtained positive electrode sheet was cold pressed, and the compaction density was 2.65g / cm 3 , record the number of cold-pressed broken strips of 1000m pole pieces, and the recorded results are shown in Table 1.

[0173] Example 3

[0174] In this embodiment, the preparation method of the positive electrode sheet is different from that of Embodiment 1 in the following aspects, and the rest is the same as that of Embodiment 1:

[0175] 475 kg of positive electrode active material LiFePO4, 10 kg of conductive agent, 15 kg of binder, and 300 kg of N-methylpyrrolidone NMP are mixed, and then stirred in a vacuum mixer to obtain a uniform positive electrode active slurry; 80 kg of nano boron nitride powder BN, 20 kg of binder polyvinylidene fluoride PVDF, and 150 kg of N-methylpyrrolidone NMP are mixed, and then stirred in a vacuum mixer to obtain a uniform non-conductive slurry.

[0176] Take the above positive electrode active slurry and non-conductive slurry, and start coating on an aluminum foil with a length of 347mm and a thickness of 15μm. The coating adopts an extrusion coating method, one out of two, leaving pole ears on both sides of the aluminum foil, and the total coating area length is 296mm. After coating and drying, an active slurry layer 12 and a non-conductive slurry layer 13 are formed on the aluminum foil, thereby obtaining a positive electrode sheet. Among them, the thickness C of the positive electrode sheet is equal to 15μm, the thickness D1 of the active slurry layer 12 is equal to the thickness D2 of the non-conductive slurry layer 13, and the lengths of each section of the active slurry layer 12 and each section of the non-conductive slurry layer 13 are not equal. According to the formula of Example 1, each section of the active slurry layer 12 is calculated, and then the length of the non-conductive slurry layer 13 is calculated by the relationship between the active slurry layer 12 and the coating area length of 296mm.

[0177] The obtained positive electrode sheet was cold pressed, and the compaction density was 2.65g / cm 3 , record the number of cold-pressed broken strips of 1000m pole pieces, and the recorded results are shown in Table 1.

[0178] Example 4

[0179] In this embodiment, the preparation method of the positive electrode sheet is different from that of Embodiment 1 in the following aspects, and the rest is the same as that of Embodiment 1:

[0180] 475 kg of positive electrode active material LiFePO4, 10 kg of conductive agent, 15 kg of binder, and 300 kg of N-methylpyrrolidone NMP are mixed, and then stirred in a vacuum mixer to obtain a uniform positive electrode active slurry; 95 kg of nano alumina powder Al2O3, 5 kg of binder polyvinylidene fluoride PVDF, and 43 kg of N-methylpyrrolidone NMP are mixed, and then stirred in a vacuum mixer to obtain a uniform non-conductive slurry.

[0181] Take the above positive electrode active slurry and non-conductive slurry, and start coating on an aluminum foil with a length of 347 mm and a thickness of 15 μm. The coating adopts an extrusion coating method, one out of two, leaving pole ears on both sides of the aluminum foil, and the total coating area length is 296 mm. After coating and drying, an active slurry layer 12 and a non-conductive slurry layer 13 are formed on the aluminum foil, thereby obtaining a positive electrode sheet. The calculation method of the active slurry layer 12 and the non-conductive slurry layer 13 in the positive electrode sheet is the same as that in Example 1.

[0182] The obtained positive electrode sheet was cold pressed, and the compaction density was 2.65g / cm 3 , record the number of cold-pressed broken strips of 1000m pole pieces, and the recorded results are shown in Table 1.

[0183] Example 5

[0184] In this embodiment, the preparation method of the positive electrode sheet is different from that of Embodiment 1 in the following aspects, and the rest is the same as that of Embodiment 1:

[0185] 475 kg of positive electrode active material LiFePO4, 10 kg of conductive agent, 15 kg of binder, and 300 kg of N-methylpyrrolidone NMP are mixed, and then stirred in a vacuum mixer to obtain a uniform positive electrode active slurry; 95 kg of nano alumina powder Al2O3, 5 kg of binder polyvinylidene fluoride PVDF, and 43 kg of N-methylpyrrolidone NMP are mixed, and then stirred in a vacuum mixer to obtain a uniform non-conductive slurry.

[0186] Take the above positive electrode active slurry and non-conductive slurry, and start coating on an aluminum foil with a length of 347mm and a thickness of 15μm. The coating adopts an extrusion coating method, one out of two, leaving pole ears on both sides of the aluminum foil, and the total coating area length is 296mm. After coating and drying, an active slurry layer 12 and a non-conductive slurry layer 13 of equal thickness are formed on the aluminum foil, thereby obtaining a positive electrode sheet. Among them, the length of each section of the active slurry layer 12 coated on the positive electrode sheet is 172mm, and the length of each section of the non-conductive slurry layer 13 is 3mm.

[0187] The method for preparing the negative electrode sheet is the same as that in Example 1.

[0188] The obtained positive electrode sheet was cold pressed, and the compaction density was 2.65g / cm 3 , record the number of cold-pressed broken strips of 1000m pole pieces, and the recorded results are shown in Table 1.

[0189] Example 6

[0190] The preparation method of the positive electrode sheet is as follows:

[0191] The positive electrode active slurry and non-conductive slurry of Example 1 are coated on an aluminum foil with a thickness of 15 μm to obtain a positive electrode sheet, wherein the thickness of the active slurry layer 12 is consistent with that of the non-conductive slurry layer 13, and the lengths of each section of the active slurry layer 12 and each section of the non-conductive slurry layer 13 are inconsistent, which is obtained according to the calculation method of Example 1, wherein n is 30, and the thickness of the positive electrode sheet C=182 μm.

[0192] After cold pressing, the obtained positive electrode sheet was die-cut, slit and wound with a negative electrode sheet with a thickness of A=126μm and a separator with a thickness of S=24μm, using a winding needle with a circumference of L of 344mm, to obtain a square wound hard shell battery cell with one pole ear per circle. Finally, the room temperature rate performance, cycle performance and low temperature discharge performance were tested, and the test results are shown in Table 2.

[0193] Example 7

[0194] The positive electrode active slurry and non-conductive slurry of the above-mentioned embodiment 1 are coated on an aluminum foil with a thickness of 15μm to prepare a positive electrode plate, wherein the thickness of the active slurry layer 12 is consistent with that of the non-conductive slurry layer 13, the length of each section of the active slurry layer 12 is 172mm, the length of each section of the non-conductive slurry layer 13 is 3mm, and the thickness of the positive electrode plate C=182μm.

[0195] The obtained positive electrode sheet was cold pressed and the negative electrode sheet with a thickness of A=126μm and an isolation layer with a thickness of S of 24μm was die-cut, slit and wound using a winding needle with a circumference of L of 344mm to obtain a square wound hard shell battery cell with one lug per circle. The lengths of the positive and negative electrode sheets in the wound hard shell battery cell are consistent with those in Example 5. Finally, the room temperature rate performance, cycle performance and low temperature discharge performance were tested, and the test results are shown in Table 2.

[0196] Example 8

[0197] The positive electrode active slurry and non-conductive slurry of the above-mentioned Example 1 are coated on an aluminum foil with a thickness of 15 μm to prepare a positive electrode plate, wherein the thickness of the active slurry layer 12 is consistent with that of the non-conductive slurry layer 13, the length of each section of the active slurry layer 12 is 170 mm, the length of each section of the non-conductive slurry layer 13 is 2 mm, and the thickness of the positive electrode plate C = 182 μm.

[0198] The obtained positive electrode sheet was cold pressed and stacked with a negative electrode sheet having a thickness of A=126 μm to obtain a stacked battery cell, wherein the lengths of the positive electrode sheet and the negative electrode sheet in each battery cell were consistent with those in Example 5. Then, the room temperature rate performance, cycle performance and low temperature discharge performance were tested, and the test results are shown in Table 2.

[0199] Comparative Example 1

[0200] The positive electrode active slurry of the above-mentioned embodiment 1 was used, and an intermittent coating method of "active slurry coating area-empty foil area-active slurry coating area-empty foil area" was adopted to obtain a positive electrode sheet, which was then cold pressed to a compaction density of 2.65 g / cm 3 , record the number of cold-pressed broken strips of 1000m pole pieces, and the recorded results are shown in Table 1.

[0201] Comparative Example 2

[0202] The positive electrode active slurry of the above embodiment 1 was used to obtain a positive electrode sheet by continuous coating, and then cold pressed to a compaction density of 2.65 g / cm 3 , record the number of cold-pressed broken strips of 1000m pole pieces, and the recorded results are shown in Table 1.

[0203] Comparative Example 3

[0204] The positive electrode active slurry and the negative electrode active material of the above-mentioned embodiment 1 were used to prepare the positive electrode sheet and the negative electrode sheet respectively by continuous coating. After cold pressing, the thickness of the positive electrode sheet was C=182 μm, and the thickness of the negative electrode sheet was A=126 μm.

[0205] The obtained positive and negative electrode sheets and the isolation layer with a thickness S of 24 μm were die-cut, slit and wound using a winding needle with a circumference L of 344 mm to obtain a square wound hard shell battery cell with a continuous coating of one tab per circle. Finally, the room temperature rate performance, cycle performance, lithium deposition at the negative electrode corner interface after cycling and low temperature discharge performance were tested. The test results are shown in Table 2.

[0206] Table 1: Comparison of the number of cold-pressed fractures of the positive electrode sheets of the embodiments and comparative examples

[0207] Cold pressing 1000m pole piece breaking times Example 1 No belt break Example 2 No belt break Example 3 No belt break Example 4 Belt break 1 time Example 5 No belt break Comparative Example 1 The belt broke 12 times, an average of 1 break every 83 meters Comparative Example 2 No belt break

[0208] Table 2: Comparison of battery performance between examples and comparative examples

[0209]

[0210] Among them, 3C discharge capacity is compared with 1C discharge capacity @25℃, which is expressed as: at 25℃, 3C first discharge capacity / 1C first discharge capacity.

[0211] 1C cycle 1500 times capacity retention rate @25℃, expressed as: at 25℃, with a charge and discharge rate of 1C, the discharge capacity at the 1500th cycle / the first discharge capacity.

[0212] It can be seen from the data in Table 1 that the battery pole piece 1 prepared by the intermittent coating method of "active slurry coating area-empty foil area-active slurry coating area-empty foil area" adopted in the prior art is prone to breakage during cold pressing, which greatly affects production efficiency and increases costs. However, when the intermittent coating method of "active slurry coating area-non-conductive slurry coating area-active slurry coating area-non-conductive slurry coating area" of the present application is adopted, when the thickness of the active slurry layer 12 is consistent with the thickness of the non-conductive slurry layer 13, the pole piece will not break during cold pressing, just like continuous coating, but the thickness of the non-conductive slurry layer 13 will affect the breakage of the pole piece during cold pressing.

[0213] It can be seen from the data in Table 2 that the battery pole piece 1 of the present application can reduce battery polarization, improve rate performance, cycle performance and low temperature performance, and can also reduce the risk of lithium plating at the corners of the wound battery and improve the safety performance of the battery.

[0214] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery pole piece, characterized in that: The battery pole piece (1) comprises a current collector (11), an active slurry layer (12), a non-conductive slurry layer (13) and a pole tab (14); along the length direction of the current collector (11), a plurality of sections of the active slurry layer (12) and a plurality of sections of the non-conductive slurry layer (13) are alternately coated on the current collector (11); and the pole tab (14) is electrically connected to the current collector (11).

2. The battery pole piece according to claim 1, characterized in that: The thickness D1 of the active paste layer (12) and the thickness D2 of the non-conductive paste layer (13) satisfy: 0<D2≤D1.

3. The battery pole piece according to claim 1, characterized in that: The pole lug (14) is connected to the position of the current collector (11) where the active slurry layer (12) is coated, and one pole lug (14) corresponds to one or two sections of the active slurry layer (12).

4. The battery pole piece according to claim 1, characterized in that: The active slurry layer (12) and the non-conductive slurry layer (13) are coated on the current collector (11) by an intermittent coating method.

5. The battery pole piece according to claim 1, characterized in that: The active slurry layer (12) and the non-conductive slurry layer (13) are coated on both sides of the current collector (11).

6. The battery pole piece according to claim 1, characterized in that: The non-conductive slurry in the non-conductive slurry layer (13) is prepared from the following raw materials in parts by weight: 80-95 parts of non-conductive nanomaterials, 5-20 parts of binders, and 43-150 parts of solvents.

7. The battery pole piece according to claim 6, characterized in that: The non-conductive nanomaterial must meet one or more of the following properties: (1) resistivity > 102Ω / cm; (2) acid and alkali resistance; (3) hardness ≥ 3 Mohs; (4) elongation ≤ 1%; (5) insoluble in water or organic solvents; (6) thermal stability > 850°C.

8. The battery pole piece according to claim 7, characterized in that: The non-conductive nanomaterial is selected from one or more of Al2O3, ZrO2, SiO2, CaSiO3, Al4C3, SiC, B4C, AlN, BN, and CaCO3.

9. A battery cell, characterized in that: It comprises a negative electrode sheet and a positive electrode sheet that cooperate with each other, and one or both of the negative electrode sheet and the positive electrode sheet are the battery electrode sheet (1) according to any one of claims 1 to 8.

10. The battery cell according to claim 9, characterized in that: The battery cell is a wound battery cell, which is formed by winding the negative electrode sheet, the positive electrode sheet and a separation layer spaced between the negative electrode sheet and the positive electrode sheet; the lengths of the active slurry layers (12) in different sections are different, the lengths of the non-conductive slurry layers (13) in different sections are different, and along the length direction of the current collector (11), the lengths of the active slurry layers (12) increase successively, and the lengths of the non-conductive slurry layers (13) increase successively; The length of the active slurry layer (12) in each section satisfies the following formula: G1=L / 2-b+(H1-K1) / 2, G n-1 =L / 2+(H n-2 -K n-2 ) / 2+(H n-1 -K n-1 ) / 2, G n =L / 2+(H n-1 -K n- 1) / 2; Among them, G1, G n-1 , G n Respectively represent the length of the active slurry layer (12) in the first section, the length of the active slurry layer (12) in the n-1 section, and the length of the active slurry layer (12) in the nth section; n≥2; L represents the circumference of the winding needle of the wound battery cell; b represents the length reserved at the head of the battery pole piece (1) when forming the wound battery core; b satisfies: 10 mm ≤ b ≤ 30 mm; H1, H n- 1. H n-2 They respectively represent the length of the semicircular arc formed at the first corner, the length of the semicircular arc formed at the n-1th corner, and the length of the semicircular arc formed at the n-2th corner from the inside to the outside of the battery electrode (1) when forming the wound battery core; K1, K n-1 , K n-2 They respectively represent the length of the non-conductive paste layer (13) formed at the first corner from the inside to the outside of the battery electrode (1) when forming the wound battery core, the length of the non-conductive paste layer (13) in the n-1th section, and the length of the non-conductive paste layer (13) in the n-2th section.

11. The battery cell according to claim 10, characterized in that: The center angle θ of the semicircular arc formed by the non-conductive slurry layer (13) at the corner of the wound battery core satisfies: 30°≤θ≤90°.

12. The battery cell according to claim 10, characterized in that: The length H of the semicircular arc formed by the battery pole piece (1) at the nth corner when forming the wound battery core is n =Π*d n / 2, where d n is the diameter of the semicircle formed by the battery pole piece at the nth corner when forming the wound battery core; When n=1, d1=(mS+2S+2A) / 1000; when n≥2, d n =(mS+2S+2A+(2S+A+C)*(n-1)) / 1000; where d n The unit is mm, m is the number of isolation layers; S is the thickness of the isolation layer, in μm; A is the thickness of the negative electrode sheet, in μm; C is the thickness of the positive electrode sheet, in μm.

13. The battery cell according to claim 10, characterized in that: When the negative electrode sheet and the positive electrode sheet are both the battery electrode sheets (1), the length of the active slurry layer (12) of the negative electrode sheet and the length of the active slurry layer (12) of the positive electrode sheet satisfy: G1'=G1”+p,G n-1 '=G n-1 ”+q,G n '=G n ”+r; Among them, G1', G n-1 ', G n ' respectively represent the length of the active paste layer of the first section of the negative electrode sheet, the length of the active paste layer of the n-1 section, and the length of the active paste layer of the n section; G1", G n-1 ”, G n " respectively represent the length of the active slurry layer of the first section, the length of the active slurry layer of the n-1 section, and the length of the active slurry layer of the nth section of the positive electrode sheet; n≥2; 10mm≤p≤30mm; 2mm≤q≤5mm; 10mm≤r≤30mm.

14. The battery cell according to claim 9, characterized in that: The battery core is a wound battery core, and one turn of the wound battery core corresponds to one pole lug (14); When the lengths of the active slurry layers (12) of each section are equal and the lengths of the non-conductive slurry layers (13) of each section are equal, the length of the active slurry layer (12) is equal to 2 / L, and the length of the non-conductive slurry layer (13) is less than 0 and less than or equal to 20 mm; wherein L represents the circumference of the winding needle of the wound battery cell.

15. The battery cell according to claim 14, characterized in that: The length of the non-conductive slurry layer (13) is less than 1 and less than or equal to 5 mm.

16. The battery cell according to claim 9, characterized in that: The battery core is a laminated battery core, the lengths of the active slurry layers (12) of each section are equal, and the lengths of the non-conductive slurry layers (13) of each section are equal; one pole ear (14) corresponds to one section of the active slurry layer (12); The pole lug (14) comprises a first pole lug (141) and a second pole lug (142), wherein the first pole lug (141) and the second pole lug (142) are alternately arranged at a position where the active slurry layer (12) is coated on the current collector (11); the active slurry layer (12) has a first side and a second side, the first pole lug (141) is arranged on the first side of a section of the active slurry layer (12), and the second pole lug (142) is arranged on the second side of a next section of the active slurry layer (12).

17. The battery cell according to claim 16, characterized in that: The length of the non-conductive slurry layer (13) is greater than 0.5 mm and less than or equal to 3.5 mm.

18. A battery, characterized in that: The battery comprises the battery cell according to any one of claims 9 to 17.

19. A battery module, characterized in that: Comprising the battery of claim 18.

20. A battery pack, characterized in that: A battery module comprising the battery module described in claim 19.

21. An electrical device, characterized in that: Comprising the battery pack as claimed in claim 20.

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