Roll core for square lithium battery and square lithium battery

Abstract

The utility model discloses a roll core for a square lithium battery and the square lithium battery, the roll core comprises a positive pole piece with a plurality of positive pole lugs, a negative pole piece with a plurality of negative pole lugs and a diaphragm positioned between the positive pole piece and the negative pole piece, all the positive pole lugs form a U-shaped positive pole lug cluster, and all the negative pole lugs form a U-shaped negative pole lug cluster; and the U-shaped positive tab cluster and the U-shaped negative tab cluster are positioned at the same end of the roll core. Compared with an existing winding cell structure with the positive electrode and the negative electrode at the same end, the effective current-carrying width of each tab is expanded, and the current-carrying area of the tabs is greatly increased; meanwhile, compared with a winding structure with different ends of a positive electrode and a negative electrode, the occupied space of the tabs is reduced, the energy density of the square lithium battery using the winding core is favorably improved, and the current-carrying capacity and the energy density of the battery using the winding core are both considered.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of lithium battery, specifically relates to a winding core for square lithium battery and square lithium battery. BACKGROUND

[0002] High rate lithium battery usually refers to the rate greater than 3C. The tab of the positive / negative electrode and the pole of the battery of high rate lithium battery need to be able to bear super large working current during charging and discharging, and the tab of the positive / negative electrode and the pole of the battery need to use the tab of the positive / negative electrode with large current-carrying area; if the current-carrying pad, current-carrying column or current-carrying block is used, these current-carrying pads, current-carrying columns or current-carrying blocks also need to be able to bear super large working current. Here, the "bearing super large working current" refers to that when the tab, current-carrying pad / current-carrying column / current-carrying block bearing super large working current passes through super large current, the tab, current-carrying pad / current-carrying column / current-carrying block will not produce too much heat due to its own ohmic resistance and the passing large current, which will not cause the temperature of the tab, current-carrying pad / current-carrying column / current-carrying block to rise too much, and will not affect the performance and safety of the battery.

[0003] The multi-tab winding core for square lithium battery is usually divided into two kinds, one is the winding core structure with the positive and negative electrodes at the same end, and the other is the winding core structure with the positive and negative electrodes at different ends.

[0004] For the winding core structure with the positive and negative electrodes at the same end, the conventional winding structure is to have tabs in the upper half of the winding core and no tabs in the lower half (see Figure 1 ) or to have only one tab per winding of the winding core, and the width of the tab cannot exceed the difference between the width / 2 of the square lithium battery and the thickness / 2 of the square lithium battery, the number of tabs is small, and the area of the gathered tabs bearing current is small, which will affect the performance and safety of the large current charging and discharging of the winding core and the square lithium battery using the winding core.

[0005] For the winding structure with the positive and negative electrodes at different ends, the tabs of the positive electrode and the tabs of the negative electrode are arranged at the two ends of the lithium battery respectively to solve the problem of tab current carrying, see Figure 2 , the positive electrode is double-sided coated with positive active material on one side of the aluminum foil (current collector), and the other side is empty aluminum foil (current collector), Figure 2 , from top to bottom, the positive tab, the aluminum oxide insulation layer and the active material coating area are arranged in sequence; see Figure 3 , the negative electrode is double-sided coated with negative active material on one side of the copper foil (current collector), and the other side is empty copper foil (current collector), Figure 3The negative tab, the active material coating area are sequentially arranged from top to bottom; during the winding of the square cell, the positive electrode and the negative electrode are wound by the separator, and the empty aluminum foil of the positive electrode and the empty copper foil of the negative electrode are arranged at two ends of the wound cell for winding, the width direction of the separator covers the active material coating area of the positive electrode and the negative electrode, and the empty aluminum foil of the positive electrode and the empty copper foil of the negative electrode beyond the separator at two ends of the wound cell are used as the positive tab and the negative tab respectively, and the positive tab and the negative tab are arranged on the same side of the cell, and the positive tab and the negative tab are arranged on the same side of the cell. Figure 4 The product of the thickness and the length of the aluminum / copper foil of the positive / negative current collector of the full-tab lithium battery is the area of the tab carrying current, although the current-carrying area is increased, the lithium battery is manufactured into the lithium battery, and the effective space in the battery is occupied more, and the battery capacity is not contributed, and the energy density of the battery is low. At the same time, the full-tab square winding core at different ends of the positive and negative electrodes uses the side of the positive / negative tab aluminum foil / copper foil with the length of the whole tab as the tab, and the current-carrying area of the increased tab is limited by the current-carrying area of the pole of the square lithium battery.

[0006] Therefore, it is necessary to provide a winding core for a square lithium battery to overcome the defects of the prior art. SUMMARY

[0007] The utility model discloses a winding core for square lithium battery and square lithium battery, aiming at being able to give consideration to current-carrying capacity and the energy density of the battery using the winding core.

[0008] In order to realize the above-mentioned purpose, the utility model provides a winding core for square lithium battery, comprising: positive tab with multiple positive tabs, negative tab with multiple negative tabs, separator between positive tab and negative tab, all positive tabs constitute U-shaped positive tab cluster, all negative tabs constitute U-shaped negative tab cluster, U-shaped positive tab cluster and U-shaped negative tab cluster are located at the same end of winding core.

[0009] In a preferred embodiment, a part of the positive tab is located above the aluminum foil of the positive tab, and the included angle between the side of the tab part of the positive tab located above the aluminum foil and the upper edge of the aluminum foil is greater than 60° and less than 90°.

[0010] In a preferred embodiment, all the sides in the U-shaped positive tab cluster are coplanar, and the side is the side of the tab part of the positive tab located above the aluminum foil.

[0011] In a preferred embodiment, a part of the negative tab is located above the copper foil of the negative tab, and the included angle between the side of the tab part of the negative tab located above the copper foil and the upper edge of the copper foil is greater than 60° and less than 90°.

[0012] In a preferred embodiment, all the sides in the U-shaped negative tab cluster are coplanar, and the side is the side of the tab part of the negative tab located above the copper foil.

[0013] In a preferred embodiment, the positive electrode sheet comprises, from top to bottom, a positive electrode tab, an alumina insulation layer, and a positive electrode active material coating region, the alumina insulation layer and the positive electrode active material coating region are both coated on the surface of the aluminum foil.

[0014] In a preferred embodiment, the positive electrode sheet comprises, from top to bottom, a positive electrode tab, and a positive electrode active material coating region, the positive electrode active material coating region is coated on the surface of the aluminum foil.

[0015] In a preferred embodiment, the negative electrode sheet comprises a copper foil, a negative electrode tab, and a negative electrode active material coating region, the negative electrode active material coating region is coated on the surface of the copper foil, and the negative electrode tab is located above the negative electrode active material coating region.

[0016] In a preferred embodiment, the U-shaped positive electrode tab cluster and the U-shaped negative electrode tab cluster are both welded to the outer tab.

[0017] The utility model also provides a square lithium battery, include the winding core, the lithium battery is soft package lithium battery.

[0018] In a preferred embodiment, the shell material of the soft package lithium battery is a soft aluminum-plastic composite film.

[0019] The utility model also provides a square lithium battery, including one end has the shell of opening, the cover board of cover is located at the shell opening department and winding core, the winding core is located in the shell, the positive electrode ear and negative electrode ear of winding core all are welded to the cover board.

[0020] In a preferred embodiment, the material of the shell is an aluminum alloy material or a steel material, and the material of the cover plate is an aluminum alloy material or a steel material.

[0021] Compared with the prior art, the winding core for the square lithium battery has a U-shaped positive electrode tab cluster and a U-shaped negative electrode tab cluster at the same end. This design expands the effective current-carrying width of each tab compared to the existing winding structure with positive and negative electrodes at the same end, greatly improves the tab current-carrying area, and improves the performance and safety of large-current charging and discharging. At the same time, compared with the winding structure with positive and negative electrodes at different ends, the tab occupies less space, which is conducive to improving the energy density of the square lithium battery using the winding core. The utility model takes into account the current-carrying capacity and the energy density of the battery using the winding core.

[0022] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the following describes a preferred embodiment of the utility model, and the accompanying drawings are as follows. BRIEF DESCRIPTION OF DRAWINGS

[0023] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a wound battery cell with the positive and negative terminals at the same end;

[0025] Figure 2 A schematic diagram of the positive electrode structure of a fully wound battery cell with different positive and negative terminals;

[0026] Figure 3 A schematic diagram of the negative electrode structure of a wound battery cell with different positive and negative terminals;

[0027] Figure 4 This is a schematic diagram of the structure of a wound battery cell with different positive and negative terminals;

[0028] Figure 5 The structural diagram of the core provided by this utility model;

[0029] Figure 6 A schematic diagram of the structure of the positive electrode sheet of the winding core provided by this utility model before winding;

[0030] Figure 7 A partial structural diagram of the positive electrode sheet of the winding core provided by this utility model before winding;

[0031] Figure 8 A schematic diagram of the structure of the negative electrode sheet of the winding core provided by this utility model before winding;

[0032] Figure 9 A partial structural diagram of the negative electrode sheet of the winding core provided by this utility model before winding;

[0033] The diagram is labeled as follows: 100, core; 11, positive electrode sheet; 111, positive electrode tab; 112, alumina insulating layer; 113, positive electrode active material coating area; 12, U-shaped positive electrode tab cluster; 13, negative electrode sheet; 131, negative electrode tab; 132, negative electrode active material coating area; 14, U-shaped negative electrode tab cluster. Detailed Implementation

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of the present application.

[0035] In the embodiments of the present application, a winding core 100 for a square lithium battery is provided.

[0036] Please refer to Figure 5 The winding core 100 comprises a positive sheet 11, a negative sheet 13, a diaphragm between the positive sheet 11 and the negative sheet 13, the positive sheet 11 has a plurality of positive tabs 111, the negative sheet 13 has a plurality of negative tabs 131, all the positive tabs 111 form a U-shaped positive tab cluster 12, all the negative tabs 131 form a U-shaped negative tab cluster 14, and the U-shaped positive tab cluster 12 and the U-shaped negative tab cluster 14 are located at the same end of the winding core 100.

[0037] In the embodiments, the number of the U-shaped positive tab cluster 12 and the U-shaped negative tab cluster 14 is one.

[0038] It can be understood that the winding core 100 for the square lithium battery is flat.

[0039] The U-shaped positive tab cluster 12 and the U-shaped negative tab cluster 14 are located at the same end of the whole winding core 100, which is referred to as the upper end of the winding core 100. A part of the positive tab 111 is located above the aluminum foil of the corresponding positive sheet 11, and a part of the negative tab 131 is located above the copper foil of the corresponding negative sheet 13.

[0040] Before being wound into the winding core 100, the structure of the positive sheet 11 is shown in Figure 6 As an example, it can be understood that the positive sheet 11 comprises an aluminum foil, the positive sheet 11 comprises a positive tab 111, an aluminum oxide insulating layer 112 and a positive active material coating area 113 arranged in sequence from top to bottom, the aluminum oxide insulating layer 112 and the positive active material coating area 113 are coated on the surface of the aluminum foil, and it can be understood that the lower end of the positive tab 111 is connected to the aluminum foil. In another embodiment, the positive sheet 11 comprises a positive tab 111 and a positive active material coating area 113 arranged in sequence from top to bottom, and the positive active material coating area 113 is coated on the surface of the aluminum foil.

[0041] Please refer toFigure 7 Specifically, the portion of the positive tab 111 above the aluminum foil before the winding of the core 100 is a trapezoid, which is referred to as a first trapezoid for distinction. The upper base of the first trapezoid is farther away from the positive active material coating area 113 of the positive tab 11 than the lower base of the first trapezoid. The angles of the two bottom corners of the first trapezoid are both greater than 60° and less than 90°. Typically, the first trapezoid is an isosceles trapezoid. It can be understood that after the winding of the core 100, the included angle between the side of the portion of the positive tab 111 above the corresponding aluminum foil and the upper edge of the aluminum foil is greater than 60° and less than 90°.

[0042] After winding, the positive tab 111 becomes a U-shaped positive tab. At this time, all the sides of the U-shaped positive tab cluster 12 are coplanar. The sides are the sides of the portion of the positive tab 111 above the aluminum foil, that is, after the winding of the first trapezoid, the two sides (the legs of the first trapezoid) are coplanar, and all the two sides of the first trapezoid are located on the same plane.

[0043] Before winding into the core 100, the structure of the negative tab 13 is shown in Figure 8 As an example, it can be understood that the negative tab 13 includes a copper foil. The negative tab 13 includes a negative tab 131, a negative active material coating area 132 arranged in sequence from top to bottom. The positive active material coating area 113 is coated on the surface of the copper foil. It can be understood that the lower end of the negative tab 131 is connected to the copper foil.

[0044] Referring to Figure 9 Specifically, the portion of the negative tab 131 above the copper foil before the winding of the core 100 is a trapezoid, which is referred to as a second trapezoid for distinction. The upper base of the second trapezoid is farther away from the negative active material coating area 132 of the negative tab 13 than the lower base of the second trapezoid. The angles of the two bottom corners of the second trapezoid are both greater than 60° and less than 90°. Typically, the second trapezoid is an isosceles trapezoid. It can be understood that after the winding of the core 100, the included angle between the side of the portion of the negative tab 131 above the corresponding copper foil and the upper edge of the copper foil is greater than 60° and less than 90°.

[0045] After winding, the negative tab 131 becomes a U-shaped negative tab. At this time, all the sides of the U-shaped negative tab cluster 14 are coplanar. The sides are the sides of the portion of the negative tab 131 above the copper foil, that is, after the winding of the second trapezoid, the two sides (the legs of the second trapezoid) are coplanar, and all the two sides of the second trapezoid are located on the same plane.

[0046] It can be understood that the U-shaped described herein can be understood as U-shaped in a top view.

[0047] In some embodiments, the U-shaped positive tab cluster 12 and the U-shaped negative tab cluster 14 are both welded to the outer tab. The U-shaped positive tab cluster 12 is welded to the positive outer tab, and the U-shaped negative tab cluster 14 is welded to the negative outer tab.

[0048] In combination with the detailed description of the specific embodiments of the present application, it can be seen that, compared with the prior art, the winding core of the present application has U-shaped positive tab clusters 12 and U-shaped negative tab clusters 14 located at the same end. Such a design utilizes the upper and lower regions of the winding core side edge winding circumferential portion without occupying the entire region. Compared with the winding core structure of the prior art with positive and negative tabs at the same end, the effective current-carrying width of each tab is expanded, the tab current-carrying area is greatly improved, the performance of high charge and discharge and the safety of high charge and discharge can be met. At the same time, compared with the winding structure with positive and negative tabs at different ends, the tab occupying space is reduced by about half, which is conducive to improving the energy density of the square lithium battery. Since the tab current-carrying area can meet the current-carrying requirement of high-power discharge, the performance of high charge and discharge and the safety are not reduced. The present application takes into account the current-carrying capacity and the battery energy density using the winding core 100, and is universal in capacity size, and can be used as a winding core of various capacities. The winding core 100 can select and design the thickness and length of the aluminum foil / copper foil, and take the square lithium battery pole current-carrying area as the benchmark.

[0049] The utility model also provides a square lithium battery, square lithium battery includes the shell of having the opening in one end, the cover board of cover setting at the shell opening, the winding core 100, the winding core 100 is located in the shell, the positive tab 111 and the negative tab 131 of winding core 100 are all welded and connect the cover board.

[0050] Specifically, the main material of the shell is aluminum alloy material or steel material, and the main material of the cover plate is aluminum alloy material or steel material.

[0051] The utility model also provides a square lithium battery, the lithium battery is soft package lithium battery, includes winding core 100.

[0052] The soft package uses an outer tab, which is an outer tab with a tab adhesive. The U-shaped positive tab cluster 12 and the U-shaped negative tab cluster 14 are both welded to the outer tab with a tab adhesive. The tab cluster of the winding core 100 is welded to the outer tab with a tab adhesive by ultrasonic welding / resistance welding / riveting. The current is conducted out of the battery's external circuit through the outer tab.

[0053] The soft package lithium battery includes the winding core 100 and the aluminum plastic film (aluminum plastic composite film) wrapped on the outer side of the winding core 100, that is, the shell material of the soft package lithium battery is a soft aluminum plastic composite film, and the outer tab extends out of the aluminum plastic film.

[0054] It can be understood that the square lithium battery adopts the winding core 100, so that the area of the lithium battery carrying current is larger, the current carrying capacity of the battery is improved, which helps to reduce the heat and temperature rise of the square lithium battery during high current discharge, improves the performance and safety of the square lithium battery, and ensures the performance and safety of the battery under high power charging and discharging. Compared with the lithium battery with winding structure of different ends of positive and negative electrodes, the effective volume of the battery for loading positive / negative active material is improved, and the energy density of the lithium battery is improved. The current carrying area of the tab can meet the current carrying requirement of high power discharge, and compared with the lithium battery with winding structure of different ends of positive and negative electrodes, the performance and safety of high charging and discharging of the battery are not reduced. Compared with the prior art, the current carrying area of the tab is compromised, so that the lithium battery has high energy density and high power charging and discharging safety, which can meet the safety performance of high power charging and discharging, and can improve the energy density compared with the full-tab square lithium battery.

[0055] It should be noted that all the directionality indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between the components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the directionality indications will also change accordingly.

[0056] In addition, the description of "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope required by the present application.

[0057] The above is only the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principle of the present application, some improvements and refinements can be made, which should be considered as the protection scope of the present application.

Claims

1. A winding core for a square lithium battery, characterized in that, include: A positive electrode sheet with multiple positive tabs, a negative electrode sheet with multiple negative tabs, and a diaphragm located between the positive and negative electrode sheets. All the positive tabs form a U-shaped positive tab cluster, and all the negative tabs form a U-shaped negative tab cluster. The U-shaped positive tab cluster and the U-shaped negative tab cluster are located at the same end of the winding core.

2. The core for a square lithium battery as described in claim 1, characterized in that, A portion of the positive electrode tab is located above the aluminum foil of the positive electrode plate, and the angle between the side of the portion of the positive electrode tab above the aluminum foil and the upper edge of the aluminum foil is greater than 60° and less than 90°.

3. A winding core for a square lithium battery as described in claim 2, characterized in that, All sides of the U-shaped positive electrode cluster are coplanar, and the side refers to the side of the portion of the positive electrode located above the aluminum foil.

4. A winding core for a square lithium battery as described in claim 1, characterized in that, A portion of the negative electrode tab is located above the copper foil of the negative electrode sheet, and the angle between the side of the portion of the negative electrode tab above the copper foil and the upper edge of the copper foil is greater than 60° and less than 90°.

5. A winding core for a square lithium battery as described in claim 4, characterized in that, All sides of the U-shaped negative electrode tab cluster are coplanar, and the side refers to the side of the portion of the negative electrode tab located above the copper foil.

6. A winding core for a square lithium battery as described in claim 1, characterized in that, The positive electrode sheet includes a positive electrode tab, an alumina insulating layer, and a positive electrode active material coating area arranged sequentially from top to bottom. The alumina insulating layer and the positive electrode active material coating area are both coated on the surface of the aluminum foil.

7. A winding core for a square lithium battery as described in claim 1, characterized in that, The negative electrode sheet includes a copper foil, a negative electrode tab, and a negative electrode active material coating area. The negative electrode active material coating area is coated on the surface of the copper foil, and the negative electrode tab is located above the negative electrode active material coating area.

8. A winding core for a square lithium battery as described in claim 1, characterized in that, Both the U-shaped positive electrode cluster and the U-shaped negative electrode cluster are welded to the outer electrode.

9. A square lithium battery, characterized in that, Includes the core as described in any one of claims 1-8, wherein the lithium battery is a pouch lithium battery.

10. A square lithium battery, characterized in that, It includes a housing with an opening at one end, a cover plate covering the opening of the housing, and a core as described in any one of claims 1-7, wherein the core is located inside the housing, and the positive and negative tabs of the core are welded to the cover plate.

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