Cylindrical lithium ion battery

Abstract

The utility model relates to the technical field of batteries, and discloses a cylindrical lithium ion battery, which comprises a positive plate, a positive plate, a negative plate, a positive electrode active material layer and a negative electrode active material layer, the two positive tabs are respectively arranged corresponding to the two positive empty foil areas between the adjacent positive active material layers; negative electrode empty foil areas are formed between the negative electrode plate and the adjacent negative electrode active material layers and at the negative electrode ending end; wherein one negative tab is positioned in a negative electrode empty foil area between adjacent negative electrode active material layers, and the other negative tab is positioned in a negative electrode empty foil area at a negative electrode ending end. According to the utility model, the diaphragm at the positive in-position end is effectively prevented from being punctured by shear force and friction force; the distance from electrons to the negative tab is shorter, the high-rate discharge temperature rise is low, the negative tab with the maximum heat production amount is moved out of the inner layer, and the dual effects of stress and heat on the diaphragm at the positive in-place end are effectively avoided, so that the diaphragm is further prevented from being punctured, and the short circuit condition of the battery is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a cylindrical lithium-ion battery. Background Art

[0002] Lithium-ion batteries are one of the most important energy storage carriers for new energy vehicles at present. Conventional cylindrical lithium-ion batteries have only one positive electrode tab and one negative electrode tab, which results in a relatively high internal resistance of the battery and poor power performance. In order to reduce the internal resistance and meet the high-power requirements of electrical equipment for lithium-ion batteries, cylindrical lithium-ion batteries with single positive and double negative electrode tabs or double positive and double negative electrode tabs are usually selected. Moreover, the battery with double positive and double negative electrode tabs is more excellent in power performance than the battery with single positive and double negative electrode tabs. However, when the battery with double positive and double negative electrode tabs is discharged at a high rate, the temperature at the electrode tab will increase (exceeding 80 °C), and the heat dissipation is slow. This high temperature will cause the separator to denature, such as the ceramic layer falling off and the strength decreasing, resulting in an increased risk of the separator being punctured and prone to the problem of short circuit between the positive and negative electrodes. In addition, with the increase in the number of high-rate charge and discharge cycles, the expansion and contraction of the negative electrode sheet will cause the separator to be repeatedly squeezed and rubbed, and the separator at the positive electrode insertion end will also be subjected to the shearing force of the end face of the positive electrode sheet, which will also easily cause the separator to be punctured, resulting in short circuit between the positive and negative electrodes. Summary of the Utility Model

[0003] In view of this, the utility model provides a cylindrical lithium-ion battery to solve the problem that the separator of the existing cylindrical lithium-ion battery has a relatively large risk of being punctured and is prone to short circuit between the positive and negative electrodes.

[0004] The utility model provides a cylindrical lithium-ion battery, comprising:

[0005] A positive electrode sheet, comprising a positive electrode current collector and a positive electrode active material layer. One end of the positive electrode current collector forms a positive electrode insertion end, and the other end forms a positive electrode finishing end. The positive electrode active material layer is coated on the positive electrode current collector at intervals between the positive electrode insertion end and the positive electrode finishing end to form positive electrode empty foil areas at the positive electrode insertion end and between adjacent positive electrode active material layers;

[0006] Two positive electrode tabs, which are respectively arranged corresponding to two positive electrode empty foil areas between adjacent positive electrode active material layers and are connected to the positive electrode current collector;

[0007] A negative electrode sheet, comprising a negative electrode current collector and a negative electrode active material layer. One end of the negative electrode current collector forms a negative electrode insertion end, and the other end forms a negative electrode finishing end. The negative electrode active material layer is coated on the negative electrode current collector at intervals between the negative electrode insertion end and the negative electrode finishing end to form negative electrode empty foil areas between adjacent negative electrode active material layers and at the negative electrode finishing end;

[0008] There are two negative tabs. One of the negative tabs is located in the negative empty foil area between adjacent negative active material layers, and the other negative tab is located in the negative empty foil area at the end of the negative electrode. The negative tab is connected to the negative current collector.

[0009] The separator is disposed between the positive electrode sheet and the negative electrode sheet so that the positive electrode sheet, the separator, and the negative electrode sheet are stacked.

[0010] In an optional embodiment, the positive empty foil area includes a first empty foil area, a second empty foil area, and a third empty foil area. The first empty foil area is located at the positive electrode insertion end, and the second empty foil area and the third empty foil area are respectively located between adjacent positive active material layers; the positive tabs include a first positive tab and a second positive tab. The first positive tab is disposed in the second empty foil area, and the second positive tab is disposed in the third empty foil area.

[0011] In an optional embodiment, the negative empty foil area includes a fourth empty foil area and a fifth empty foil area. The fourth empty foil area is located between adjacent negative active material layers, and the fifth empty foil area is located at the end of the negative electrode; the negative tabs include a first negative tab and a second negative tab. The first negative tab is disposed in the fourth empty foil area, and the second negative tab is disposed in the fifth empty foil area.

[0012] In an optional embodiment, the first positive tab and the first negative tab are disposed opposite to each other and are respectively disposed on opposite sides of the separator corresponding to the same position of the separator.

[0013] In an optional embodiment, the first positive tab and the second positive tab are aligned on the same side in the diameter direction of the cylindrical lithium-ion battery.

[0014] In an optional embodiment, the cylindrical lithium-ion battery further includes a positive electrode insulating sheet. The edge of the positive electrode insulating sheet is connected to the positive active material layer and is disposed corresponding to the positive empty foil area; and / or,

[0015] The cylindrical lithium-ion battery further includes a negative electrode insulating sheet. The edge of the negative electrode insulating sheet is connected to the negative active material layer and is disposed corresponding to the negative empty foil area.

[0016] In an optional embodiment, along the winding direction, the connection width f between the positive electrode insulating sheet and the positive active material layer is 1 mm to 3 mm;

[0017] Along the winding direction, the connection width g between the negative electrode insulating sheet and the negative active material layer is 1 mm to 3 mm.

[0018] In an alternative embodiment, along the winding direction, the positive electrode insertion end and the negative electrode insertion end are arranged offset with respect to the separator.

[0019] In an alternative embodiment, along the winding direction, the width a of the first empty foil area is 12 mm to 18 mm, the width b of the second empty foil area is 10 mm to 15 mm, and the width c of the third empty foil area is 10 mm to 15 mm.

[0020] In an alternative embodiment, along the winding direction, the width d of the fourth empty foil area is 5 mm to 15 mm, and the width e of the fifth empty foil area is 5 mm to 15 mm.

[0021] The present utility model provides a cylindrical lithium-ion battery, which forms a positive electrode empty foil area at the positive electrode insertion end of the positive electrode sheet. Therefore, the positive electrode current collector is in contact with the separator at the positive electrode insertion end, which can effectively avoid the separator at the positive electrode insertion end from being subjected to shear force and frictional force, thereby preventing the separator from being punctured, and further preventing the occurrence of positive and negative electrode short-circuit problems. Moreover, one of the negative electrode tabs is arranged in the negative electrode empty foil area between adjacent negative electrode active material layers, and the other negative electrode tab is arranged in the negative electrode empty foil area at the end of the negative electrode, so that the distance for electrons to transmit to the negative electrode tab is shorter, thereby making the current distribution on the electrode sheet more uniform, the internal resistance of the battery lower, the power performance better, and the temperature rise during high-rate discharge lower, which is more conducive to maintaining the stability of the separator. At the same time, moving the negative electrode tab with the largest heat generation out of the inner layer is more conducive to heat dissipation, and further can effectively avoid the separator at the positive electrode insertion end from being subjected to the dual action of force and heat, thereby further avoiding the separator from being punctured and the occurrence of battery short-circuit conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 It is a schematic diagram of the laminated structure of the positive electrode sheet, separator and negative electrode sheet of the embodiment of the present utility model;

[0024] Figure 2 It is a schematic diagram of the structure of the positive electrode sheet, positive electrode tab and positive electrode insulating sheet of the embodiment of the present utility model;

[0025] Figure 3 It is a schematic diagram of the structure of the negative electrode sheet, negative electrode tab and negative electrode insulating sheet of the embodiment of the present utility model;

[0026] Figure 4Schematic structural diagram of the core of the embodiment of the present utility model;

[0027] Figure 5 Top view structural diagram at the positive electrode insertion end and negative electrode insertion end of the core of the embodiment of the present utility model;

[0028] Figure 6 Schematic stacked structure diagram of a positive electrode sheet, a separator, and a negative electrode sheet in the related art;

[0029] Figure 7 Comparison chart of the charge and discharge cycle test results of the cylindrical lithium-ion battery of Example 1 and the cylindrical lithium-ion battery of Comparative Example 1;

[0030] Figure 8 Surface diagram of the separator disassembled after the charge and discharge cycle test of the cylindrical lithium-ion battery of Example 1;

[0031] Figure 9 Surface diagram of the separator disassembled after the charge and discharge cycle test of the cylindrical lithium-ion battery of Comparative Example 1;

[0032] Figure 10 Comparison chart of the results of the rate discharge performance test of the cylindrical lithium-ion battery of Example 1 and the cylindrical lithium-ion battery of Comparative Example 1;

[0033] Figure 11 Comparison chart of the results of temperature monitoring during the rate discharge performance test of the cylindrical lithium-ion battery of Example 1 and the cylindrical lithium-ion battery of Comparative Example 1.

[0034] Explanation of reference numerals:

[0035] 1. Positive electrode sheet; 11. Positive electrode current collector; 111. Positive electrode insertion end; 112. Positive electrode end; 12. Positive electrode active material layer; 13. Positive electrode empty foil area; 131. First empty foil area; 132. Second empty foil area; 133. Third empty foil area; 134. Sixth empty foil area; 2. Positive electrode tab; 21. First positive electrode tab; 22. Second positive electrode tab; 3. Negative electrode sheet; 31. Negative electrode current collector; 311. Negative electrode insertion end; 312. Negative electrode end; 32. Negative electrode active material layer; 33. Negative electrode empty foil area; 331. Fourth empty foil area; 332. Fifth empty foil area; 333. Seventh empty foil area; 4. Negative electrode tab; 41. First negative electrode tab; 42. Second negative electrode tab; 5. Separator; 6. Positive electrode insulating sheet; 7. Negative electrode insulating sheet. Detailed implementation manners

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Apparently, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0037] The following will describe the embodiments of the present utility model in conjunction with Figures 1 to 11 , to describe the embodiments of the present utility model.

[0038] According to an embodiment of the present utility model, a cylindrical lithium-ion battery is provided, as Figures 1 to 5 shown, including: a positive electrode sheet 1, a positive electrode tab 2, a negative electrode sheet 3, a negative electrode tab 4, and a separator 5.

[0039] As Figure 1 and Figure 2 shown, the positive electrode sheet 1 includes a positive electrode current collector 11 and a positive electrode active material layer 12. One end of the positive electrode current collector 11 forms a positive electrode insertion end 111, and the other end forms a positive electrode end 112. The positive electrode active material layer 12 is coated on the positive electrode current collector 11 at intervals between the positive electrode insertion end 111 and the positive electrode end 112 to form a positive electrode empty foil area 13 at the positive electrode insertion end 111 and between adjacent positive electrode active material layers 12. There are two positive electrode tabs 2, and the two positive electrode tabs 2 are respectively arranged corresponding to the two positive electrode empty foil areas 13 between adjacent positive electrode active material layers 12 and are connected to the positive electrode current collector 11.

[0040] As Figure 1 and Figure 3 shown, the negative electrode sheet 3 includes a negative electrode current collector 31 and a negative electrode active material layer 32. One end of the negative electrode current collector 31 forms a negative electrode insertion end 311, and the other end forms a negative electrode end 312. The negative electrode active material layer 32 is coated on the negative electrode current collector 31 at intervals between the negative electrode insertion end 311 and the negative electrode end 312 to form a negative electrode empty foil area 33 between adjacent negative electrode active material layers 32 and at the negative electrode end 312. There are two negative electrode tabs 4, one of the negative electrode tabs 4 is located in the negative electrode empty foil area 33 between adjacent negative electrode active material layers 32, and the other negative electrode tab 4 is located in the negative electrode empty foil area 33 at the negative electrode end 312. The negative electrode tabs 4 are connected to the negative electrode current collector 31.

[0041] As Figure 1 shown, the separator 5 is arranged between the positive electrode sheet 1 and the negative electrode sheet 3 so that the positive electrode sheet 1, the separator 5, and the negative electrode sheet 3 are stacked.

[0042] In the cylindrical lithium-ion battery of this embodiment, a positive electrode empty foil area 13 is formed at the positive electrode insertion end 111 of the positive electrode sheet 1. Therefore, at the positive electrode insertion end 111, the positive electrode current collector 11 is in contact with the separator 5, which can effectively avoid the separator 5 at the positive electrode insertion end 111 from being subjected to shear force and friction force, thereby preventing the separator 5 from being punctured, and further preventing the occurrence of positive and negative electrode short-circuit problems. Moreover, one of the negative electrode tabs 4 is arranged in the negative electrode empty foil area 33 between adjacent negative electrode active material layers 32, and the other negative electrode tab 4 is arranged in the negative electrode empty foil area 33 at the negative electrode end 312, so that the distance for electrons to transfer to the negative electrode tab 4 is shorter, thereby making the current distribution on the electrode sheet more uniform, the internal resistance of the battery lower, the power performance better, and the temperature rise during high-rate discharge lower, which is more conducive to maintaining the stability of the separator 5. At the same time, moving the negative electrode tab 4 with the largest heat generation out of the inner layer is more conducive to heat dissipation, and further can effectively avoid the separator 5 at the positive electrode insertion end 111 from being subjected to the dual action of force and heat, thereby further avoiding the separator 5 from being punctured and the occurrence of battery short-circuit conditions.

[0043] Therefore, the cylindrical lithium-ion battery of this embodiment effectively solves the problem of the separator 5 being punctured during high-rate charge and discharge cycles, thereby reducing the risk of positive and negative electrode short-circuit of the battery and ensuring the safe use of the battery. At the same time, the cylindrical lithium-ion battery of this embodiment also has a certain improvement in rate performance.

[0044] It should be noted that the positive electrode insertion end 111 is the end of the positive electrode sheet 1 located in the middle of the battery cell after being wound into a battery cell, that is, the end corresponding to and cooperating with the winding needle during winding, and it is wound first around the winding needle as the axis; correspondingly, the positive electrode end 112 is the end of the positive electrode sheet 1 located in the outermost layer of the battery cell after being wound into a battery cell, that is, the end wound last around the winding needle as the axis. Similarly, the negative electrode insertion end 311 is the end of the negative electrode sheet 3 located in the middle of the battery cell after being wound into a battery cell, and the negative electrode end 312 is the end of the negative electrode sheet 3 located in the outermost layer of the battery cell after being wound into a battery cell.

[0045] In one embodiment, as Figure 1 and Figure 2 shown, the positive electrode empty foil area 13 includes a first empty foil area 131, a second empty foil area 132, and a third empty foil area 133. The first empty foil area 131 is located at the positive electrode insertion end 111, and the second empty foil area 132 and the third empty foil area 133 are respectively located between adjacent positive electrode active material layers 12; the positive electrode tab 2 includes a first positive electrode tab 21 and a second positive electrode tab 22. The first positive electrode tab 21 is arranged in the second empty foil area 132, and the second positive electrode tab 22 is arranged in the third empty foil area 133.

[0046] Specifically, in this embodiment, as Figure 1 and Figure 2 shown, along the winding direction ( Figure 1 and Figure 2As shown in the left - right direction, three positive electrode active material layers 12 are sequentially and spacedly arranged on the positive electrode current collector 11, and a first empty foil area 131 is formed at the left end (positive electrode insertion end 111) of the positive electrode current collector 11. A second empty foil area 132 is formed between the first positive electrode active material layer 12 and the second positive electrode active material layer 12, and a third empty foil area 133 is formed between the second positive electrode active material layer 12 and the third positive electrode active material layer 12. The first positive electrode tab 21 is welded to the positive electrode current collector 11 at the second empty foil area 132, and the second positive electrode tab 22 is welded to the positive electrode current collector 11 at the third empty foil area 133.

[0047] Further, as Figure 1 and Figure 2 shown, a sixth empty foil area 134 is formed at the right end (positive electrode ending end 112) of the positive electrode current collector 11.

[0048] In one embodiment, as Figure 1 and Figure 3 shown, the negative electrode empty foil area 33 includes a fourth empty foil area 331 and a fifth empty foil area 332. The fourth empty foil area 331 is located between adjacent negative electrode active material layers 32, and the fifth empty foil area 332 is located at the negative electrode ending end 312; the negative electrode tab 4 includes a first negative electrode tab 41 and a second negative electrode tab 42. The first negative electrode tab 41 is arranged in the fourth empty foil area 331, and the second negative electrode tab 42 is arranged in the fifth empty foil area 332.

[0049] Specifically, in this embodiment, as Figure 1 and Figure 3 shown, along the winding direction ( Figure 1 and Figure 3 shown in the left - right direction), two negative electrode active material layers 32 are sequentially and spacedly arranged on the negative electrode current collector 31, and a fourth empty foil area 331 is formed between the two negative electrode active material layers 32. A fifth empty foil area 332 is formed at the right end (negative electrode ending end 312) of the negative electrode current collector 31. The first negative electrode tab 41 is welded to the negative electrode current collector 31 at the fourth empty foil area 331, and the second negative electrode tab 42 is welded to the negative electrode current collector 31 at the fifth empty foil area 332.

[0050] Further, as Figure 1 and Figure 3 shown, a seventh empty foil area 333 is formed at the left end (negative electrode insertion end 311) of the negative electrode current collector 31.

[0051] In one embodiment, as Figure 1 shown, the first positive electrode tab 21 and the first negative electrode tab 41 are oppositely arranged and are respectively disposed on opposite sides of the separator 5 at the same position corresponding to the separator 5.

[0052] It should be noted that in the related art, as Figure 6As shown, the two negative electrode tabs are respectively located at the negative electrode insertion end and the negative electrode finishing end, so that the negative electrode tab at the negative electrode insertion end is located at the middle position of the core. In this embodiment, the first negative electrode tab 41 is arranged corresponding to the first positive electrode tab 21, which not only makes the current distribution more uniform, has a lower internal resistance, better power performance of the battery, and reduces the temperature rise during high-rate charge and discharge, but also makes the first negative electrode tab 41 away from the middle position of the core, which is more conducive to heat dissipation. Further, the first negative electrode tab 41 that generates more heat is arranged away from the positive electrode insertion end 111, so as to prevent the separator 5 at the positive electrode insertion end 111 from being punctured under the dual action of force and heat.

[0053] In one embodiment, as Figure 4 shown, the first positive electrode tab 21 and the second positive electrode tab 22 are aligned on the same side in the diameter direction of the cylindrical lithium-ion battery. Such an arrangement makes the current distribution on the core more uniform and is more convenient for the first positive electrode tab 21 and the second positive electrode tab 22 to be welded together.

[0054] In one embodiment, as Figure 1 and Figure 2 shown, the cylindrical lithium-ion battery further includes a positive electrode insulating sheet 6, and the edge of the positive electrode insulating sheet 6 is connected to the positive electrode active material layer 12 and is arranged corresponding to the positive electrode empty foil area 13.

[0055] In one embodiment, as Figure 1 and Figure 3 shown, the cylindrical lithium-ion battery further includes a negative electrode insulating sheet 7, and the edge of the negative electrode insulating sheet 7 is connected to the negative electrode active material layer 32 and is arranged corresponding to the negative electrode empty foil area 33.

[0056] The positive electrode empty foil area 13 is covered by the positive electrode insulating sheet 6, and the negative electrode empty foil area 33 is covered by the negative electrode insulating sheet 7, so as to prevent the positive electrode sheet 1 and the negative electrode sheet 3 from coming into contact after the separator 5 is punctured and prevent the battery from short-circuiting.

[0057] In one embodiment, the materials of the positive electrode insulating sheet 6 and the negative electrode insulating sheet 7 are PET or PI. The insulating sheets made of PET or PI can withstand relatively high temperatures, thus ensuring the safe use of the battery.

[0058] In one embodiment, as Figure 1 shown, the positive electrode active material layer 12 is symmetrically arranged on the opposite two sides of the positive electrode current collector 11.

[0059] In one embodiment, as Figure 1 shown, along the winding direction, the length of the negative electrode active material layer 32 on the upper right side of the negative electrode current collector 31 is greater than the length of the negative electrode active material layer 32 on the lower right side of the negative electrode current collector 31. That is, the length of the upper surface of the fifth empty foil area 332 is less than the length of the lower surface of the fifth empty foil area 332.

[0060] In one embodiment, as Figure 2 shown, along the winding direction, the connection width f between the positive electrode insulating sheet 6 and the positive electrode active material layer 12 is 1 mm to 3 mm; as Figure 3 shown, along the winding direction, the connection width g between the negative electrode insulating sheet 7 and the negative electrode active material layer 32 is 1 mm to 3 mm.

[0061] In one embodiment, as Figure 1 and Figure 5 shown, along the winding direction, the positive electrode insertion end 111 and the negative electrode insertion end 311 are arranged offset with respect to the separator 5. With such an arrangement, contact between the positive electrode insertion end 111 and the negative electrode insertion end 311 is avoided, thereby preventing the occurrence of a short - circuit problem.

[0062] In one embodiment, as Figure 2 shown, along the winding direction, the width a of the first empty foil area 131 is 12 mm to 18 mm, the width b of the second empty foil area 132 is 10 mm to 15 mm, and the width c of the third empty foil area 133 is 10 mm to 15 mm.

[0063] Furthermore, as Figure 2 shown, along the winding direction, the width h of the sixth empty foil area 134 is 1 mm to 10 mm.

[0064] In one embodiment, as Figure 2 shown, along the winding direction, the length j of the positive electrode insulating sheet 6 covering the first empty foil area 131 is 14 mm to 22 mm.

[0065] In one embodiment, as Figure 3 shown, along the winding direction, the width d of the fourth empty foil area 331 is 5 mm to 15 mm, and the width e of the fifth empty foil area 332 is 5 mm to 15 mm.

[0066] Furthermore, as Figure 3 shown, along the winding direction, the width i of the seventh empty foil area 333 is 3 mm to 11 mm.

[0067] In one embodiment, as Figure 3 shown, along the winding direction, the length k of the negative electrode insulating sheet 7 covering the seventh empty foil area 333 is 4 mm to 14 mm.

[0068] In one embodiment, the first positive electrode tab 21 and the second positive electrode tab 22 are aluminum strips.

[0069] In one embodiment, along the winding direction, the width of the first positive tab 21 is 2 mm to 8 mm, and the width of the second positive tab 22 is 3 mm to 7 mm. The thickness of the first positive tab 21 is 0.07 mm to 0.15 mm, and the thickness of the second positive tab 22 is 0.07 mm to 0.15 mm.

[0070] In one embodiment, along the winding direction, the width of the first negative tab 41 is 2 mm to 5 mm, and the width of the second negative tab 42 is 2 mm to 6 mm. Along the direction perpendicular to the winding direction (i.e., Figure 2 and Figure 3 the up-and-down direction in

[0071] When manufacturing the cylindrical lithium-ion battery of this embodiment, the steps are as follows:

[0072] Step S1: The positive electrode paste is coated on the positive electrode current collector 11 at intervals to form positive electrode active material layers 12 arranged at intervals in sequence. Between adjacent positive electrode active material layers 12, a combination of a first empty foil area 131 and a sixth empty foil area 134, a second empty foil area 132, and a third empty foil area 133 are formed in sequence, and then drying, rolling, and slitting are performed to form a preliminary positive electrode sheet 1;

[0073] Step S2: The first positive tab 21 is welded to the positive electrode current collector 11 corresponding to the second empty foil area 132, and the second positive tab 22 is welded to the positive electrode current collector 11 corresponding to the third empty foil area 133;

[0074] Step S3: Positive electrode insulating sheets 6 are covered on the combination of the first empty foil area 131 and the sixth empty foil area 134, the second empty foil area 132, and the third empty foil area 133;

[0075] Step S4: Cutting is performed at the combination of the first empty foil area 131 and the sixth empty foil area 134 to form the first empty foil area 131 and the sixth empty foil area 134, and the final positive electrode sheet 1 is obtained;

[0076] Step S5: The negative electrode paste is coated on the negative electrode current collector 31 at intervals to form negative electrode active material layers 32 arranged at intervals in sequence. Between adjacent negative electrode active material layers 32, a combination of a seventh empty foil area 333 and a fifth empty foil area 332 and a fourth empty foil area 331 are formed in sequence, and then drying, rolling, and slitting are performed to form a preliminary negative electrode sheet 3;

[0077] Step S6: The first negative tab 41 is welded to the negative electrode current collector 31 corresponding to the fourth empty foil area 331, and the second negative tab 42 is welded to the negative electrode current collector 31 corresponding to the fifth empty foil area 332;

[0078] Step S7: Cover the combination of the seventh empty foil area 333 and the fifth empty foil area 332 and the fourth empty foil area 331 with the negative electrode insulating sheet 7;

[0079] Step S8: Cut at the combination of the seventh empty foil area 333 and the fifth empty foil area 332 to form the seventh empty foil area 333 and the fifth empty foil area 332, obtaining the final negative electrode sheet 3;

[0080] Step S9: Set the separator 5 between the positive electrode sheet 1 obtained in Step S4 and the negative electrode sheet 3 obtained in Step S8, and make the first positive electrode tab 21 and the first negative electrode tab 41 correspond to the same position of the separator 5, and then wind. When winding, the head of the positive electrode insulating sheet 6 corresponding to the first empty foil area 131 falls on the negative electrode insulating sheet 7 corresponding to the seventh empty foil area 333. After winding into a core, the first positive electrode tab 21 and the second positive electrode tab 22 are aligned on the same side in the diameter direction of the core. Ultrasonic welding is performed on the first positive electrode tab 21 and the second positive electrode tab 22 to form the final core;

[0081] Step S10: Assemble the core into a shell and inject electrolyte to form a cylindrical lithium-ion battery. After the formation process, the cylindrical lithium-ion battery is activated.

[0082] It should be noted that in Step S3, the positive electrode insulating sheet 6 corresponding to the combination of the first empty foil area 131 and the sixth empty foil area 134 can be two positive electrode insulating sheets 6 respectively covering the first empty foil area 131 and the sixth empty foil area 134, and there is a certain interval between the two positive electrode insulating sheets 6, which is convenient for cutting in Step S4. In Step S7, the negative electrode insulating sheet 7 corresponding to the combination of the seventh empty foil area 333 and the fifth empty foil area 332 can be two negative electrode insulating sheets 7 respectively covering the seventh empty foil area 333 and the fifth empty foil area 332, and there is a certain interval between the two negative electrode insulating sheets 7, which is convenient for cutting in Step S8.

[0083] It should be noted that please refer to Figure 5 , along the winding direction, on the outer side of the negative electrode sheet 3, the distance m between the head of the negative electrode insulating sheet 7 corresponding to the seventh empty foil area 333 and the head of the positive electrode insulating sheet 6 corresponding to the first empty foil area 131 is 1 mm to 5 mm; along the winding direction, on the inner side of the negative electrode sheet 3, the distance n between the head of the positive electrode insulating sheet 6 corresponding to the first empty foil area 131 and the tail of the negative electrode insulating sheet 7 corresponding to the seventh empty foil area 333 is 1 mm to 10 mm.

[0084] The cylindrical lithium-ion battery of Example 1 and the cylindrical lithium-ion battery of Comparative Example 1 are tested and compared below. Among them, the cylindrical lithium-ion battery of Example 1 is the cylindrical lithium-ion battery of this embodiment, and the cylindrical lithium-ion battery of Comparative Example 1 is Figure 6The cylindrical lithium-ion battery formed by winding the positive electrode sheet 1, the negative electrode sheet 3, and the separator 5 shown.

[0085] The charge and discharge cycle tests were carried out on the cylindrical lithium-ion battery of Example 1 and the cylindrical lithium-ion battery of Comparative Example 1. The test environment was at room temperature, the voltage was 4.2 - 2.5V, and the current was +1.5C / -5C. The test results are as Figure 7 shown, Figure 7 In the figure, curve A is the battery cycle condition of Example 1, Figure 7 In the figure, curve B is the battery cycle condition of Comparative Example 1. By comparison, it can be obtained that the battery of Comparative Example 1 has an abnormal voltage phenomenon caused by internal short circuit in the later stage of the cycle. After 500 cycles, the capacity retention rate of the battery drops rapidly. And, the batteries of Example 1 and Comparative Example 1 were disassembled, as Figure 8 shown, the separator 5 of the battery of Example 1 is intact, while as Figure 9 shown, there are phenomena of porcelain peeling and puncturing of the separator 5 at the positive electrode insertion end 111 of the battery of Comparative Example 1.

[0086] The rate discharge performance tests were carried out on the cylindrical lithium-ion battery of Example 1 and the cylindrical lithium-ion battery of Comparative Example 1. Specifically, after charging at 1.5C to 4.2V, constant voltage charging was carried out until it was cut off at 0.1A, and then discharging was carried out at different rates (0.2C / 2.5C / 5C / 7.5C / 10C). At the same time, the battery temperature during the rate discharge performance test was monitored, and each battery was tested twice. The rate discharge performance test results are as Figure 10 shown. In terms of the ratio of the capacity retention rate of the battery discharged at 2.5C, 5C, 7.5C, and 10C to the capacity retention rate of the battery discharged at 0.2C, the ratios of the batteries of Example 1 are all higher than those of the batteries of Comparative Example 1; taking the ratio of the capacity retention rate of the battery discharged at 10C to the capacity retention rate of the battery discharged at 0.2C as an example, the ratio of the battery of Example 1 is 93.3%, which is higher than the ratio of 91.6% of the battery of Comparative Example 1. The temperature monitoring results of the rate discharge performance test are as Figure 11 shown. It can be seen from Figure 11 that in terms of the discharge temperature at 2.5C, 5C, 7.5C, and 10C, the discharge temperatures of the batteries of Example 1 are all lower than those of the batteries of Comparative Example 1. For example, the 10C discharge temperature of the battery of Example 1 is about 73°C, and the 10C discharge temperature of the battery of Comparative Example 1 is about 87°C.

[0087] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A cylindrical lithium-ion battery, characterized in that: include: A positive electrode sheet (1) comprises a positive electrode current collector (11) and a positive electrode active material layer (12), wherein one end of the positive electrode current collector (11) forms a positive electrode entry end (111) and the other end forms a positive electrode end end (112), and the positive electrode active material layer (12) is coated on the positive electrode current collector (11) at intervals between the positive electrode entry end (111) and the positive electrode end end (112), so as to form a positive electrode empty foil area (13) at the positive electrode entry end (111) and between adjacent positive electrode active material layers (12); Two positive electrode tabs (2) are provided, and the two positive electrode tabs (2) are respectively provided corresponding to the two positive electrode hollow foil areas (13) located between adjacent positive electrode active material layers (12), and are connected to the positive electrode current collector (11); A negative electrode sheet (3) comprises a negative electrode current collector (31) and a negative electrode active material layer (32), wherein one end of the negative electrode current collector (31) forms a negative electrode entry end (311) and the other end forms a negative electrode end end (312), and the negative electrode active material layer (32) is coated on the negative electrode current collector (31) at intervals between the negative electrode entry end (311) and the negative electrode end end (312), so as to form a negative electrode empty foil area (33) between adjacent negative electrode active material layers (32) and at the negative electrode end end (312); Two negative electrode ears (4) are provided, one of which is located in the negative electrode empty foil area (33) between adjacent negative electrode active material layers (32), and the other negative electrode ear (4) is located in the negative electrode empty foil area (33) at the negative electrode tail end (312), and the negative electrode ear (4) is connected to the negative electrode current collector (31); The separator (5) is arranged between the positive electrode sheet (1) and the negative electrode sheet (3), so that the positive electrode sheet (1), the separator (5) and the negative electrode sheet (3) are stacked.

2. The cylindrical lithium-ion battery according to claim 1, characterized in that: The positive electrode empty foil area (13) comprises a first empty foil area (131), a second empty foil area (132) and a third empty foil area (133), wherein the first empty foil area (131) is located at the positive electrode entry end (111), and the second empty foil area (132) and the third empty foil area (133) are respectively located between adjacent positive electrode active material layers (12); the positive electrode ear (2) comprises a first positive electrode ear (21) and a second positive electrode ear (22), wherein the first positive electrode ear (21) is arranged in the second empty foil area (132), and the second positive electrode ear (22) is arranged in the third empty foil area (133).

3. The cylindrical lithium-ion battery according to claim 2, characterized in that: The negative electrode empty foil area (33) comprises a fourth empty foil area (331) and a fifth empty foil area (332), wherein the fourth empty foil area (331) is located between adjacent negative electrode active material layers (32), and the fifth empty foil area (332) is located at the negative electrode tail end (312); the negative electrode ear (4) comprises a first negative electrode ear (41) and a second negative electrode ear (42), wherein the first negative electrode ear (41) is arranged in the fourth empty foil area (331), and the second negative electrode ear (42) is arranged in the fifth empty foil area (332).

4. The cylindrical lithium-ion battery according to claim 3, characterized in that: The first positive electrode tab (21) and the first negative electrode tab (41) are arranged opposite to each other and are arranged on two opposite sides of the diaphragm (5) corresponding to the same position of the diaphragm (5).

5. The cylindrical lithium-ion battery according to any one of claims 2 to 4, characterized in that: The first positive electrode tab (21) and the second positive electrode tab (22) are aligned on the same side in the diameter direction of the cylindrical lithium-ion battery.

6. The cylindrical lithium-ion battery according to any one of claims 1 to 4, characterized in that: The cylindrical lithium-ion battery further comprises a positive electrode insulating sheet (6), the edge of which is connected to the positive electrode active material layer (12) and is arranged corresponding to the positive electrode empty foil area (13); and / or, The cylindrical lithium-ion battery further comprises a negative electrode insulating sheet (7), the edge of which is connected to the negative electrode active material layer (32) and is arranged corresponding to the negative electrode empty foil area (33).

7. The cylindrical lithium-ion battery according to claim 6, characterized in that: Along the winding direction, the connection width f between the positive electrode insulating sheet (6) and the positive electrode active material layer (12) is 1 mm to 3 mm; Along the winding direction, the connection width g between the negative electrode insulating sheet (7) and the negative electrode active material layer (32) is 1 mm to 3 mm.

8. The cylindrical lithium-ion battery according to any one of claims 1 to 4, characterized in that: Along the winding direction, the positive electrode insertion end (111) and the negative electrode insertion end (311) are staggeredly arranged corresponding to the separator (5).

9. The cylindrical lithium-ion battery according to any one of claims 2 to 4, characterized in that: Along the winding direction, the width a of the first empty foil area (131) is 12 mm to 18 mm, the width b of the second empty foil area (132) is 10 mm to 15 mm, and the width c of the third empty foil area (133) is 10 mm to 15 mm.

10. The cylindrical lithium ion battery according to claim 3 or 4, characterized in that: Along the winding direction, the width d of the fourth empty foil area (331) is 5 mm to 15 mm, and the width e of the fifth empty foil area (332) is 5 mm to 15 mm.

Images