Electrode assembly, cylindrical battery, battery module and battery pack

Abstract

Electrode assembly (100) configured for a battery (1000), wherein the electrode assembly (100) comprises: several anode electrodes (10), each of the several anode electrodes (10) comprising an anode coating area (11) and at least one anode drain (12), wherein at least one anode drain (12) is arranged outside the anode coating area (11); several cathode electrodes (20), each of the several cathode electrodes (20) comprising a cathode coating area (21) and at least one cathode drain (22), wherein at least one cathode drain (22) is arranged outside the cathode coating area (21);several separators (40), wherein the several anode coating areas (11), the several separators (40) and the several cathode coating areas (21) are stacked together and arranged alternately, with a corresponding separator (40) arranged between each anode coating area (11) and the corresponding cathode coating area (21).

Description

Pole assembly, cylindrical battery, battery module and battery pack

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 15, 2024, with application number 202410302655.8. The entire contents of the above application are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a pole piece assembly, a cylindrical battery, a battery module and a battery pack. Background Art

[0003] The cylindrical battery includes a core assembly, wherein the core assembly includes a positive electrode sheet, a negative electrode sheet and a separator arranged between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and the negative electrode sheet are respectively wound layer by layer to form the core assembly. A positive electrode tab is connected to one end of the positive electrode sheet, and a negative electrode tab is connected to one end of the negative electrode sheet. The positive electrode tab and the negative electrode tab are used to transmit current.

[0004] In order to improve the energy density and assembly efficiency of cylindrical batteries, the relevant technology mainly increases the size of cylindrical batteries. Large-sized cylindrical batteries often adopt a full-tab structure to further improve their rate performance.

[0005] For cylindrical batteries with full-tab structures, the inner and outer rings of the positive and negative pole pieces usually need to be cut to leave space between the pole pieces. This is to allow current to be directly transmitted through the inner and outer ring current collectors. The current path in the area corresponding to the inner ring of the pole piece can refer to path 2 as shown in Figure 2, the current path in the area corresponding to the outer ring of the pole piece can refer to path 3 as shown in Figure 2, and the current path in the area where the pole piece tabs are located can refer to path 1 as shown in Figure 2. SUMMARY OF THE INVENTION

[0006] In a wound battery structure, a single electrode sheet is wound. As the battery diameter increases, the length of the wound electrode sheet also increases accordingly. Because the electrode sheet is wound continuously, the resistance of each electrode sheet forms a series structure. In this series structure, the current in each electrode sheet passes through all parts of the electrode sheet, and the resistance is added up.

[0007] In a wound battery structure, as battery height increases, the current path length in the wound structure also increases, causing the current path through the core (Path 1 shown in Figure 2) to increase in length and resistance. Because the current needs to pass through the wound electrode to function properly, the resistance of the electrode through which the current passes is added together, resulting in an increase in the internal resistance of the core.

[0008] As the battery diameter increases, the circumference of the avoidance layer of the outer ring under the winding structure increases, which may lead to an increase in the length of the tab portion cut off, thereby increasing the length of path 3 as shown in Figure 2, indirectly leading to an increase in the internal resistance of the battery.

[0009] Therefore, as the battery size increases, the internal resistance of the cylindrical battery will increase, which in turn affects the battery rate performance.

[0010] In a first aspect, an embodiment of the present application provides a pole piece assembly for a battery, the pole piece assembly comprising:

[0011] A plurality of negative electrode sheets, each of the negative electrode sheets comprising a negative electrode coating portion and at least one negative electrode tab, wherein at least one negative electrode tab is located outside the negative electrode coating portion;

[0012] A plurality of positive electrode sheets, each of the positive electrode sheets comprising a positive electrode coating portion and at least one positive electrode tab, wherein at least one positive electrode tab is located outside the positive electrode coating portion;

[0013] A plurality of separators, a plurality of the negative electrode coating parts, a plurality of the separators and a plurality of the positive electrode coating parts are stacked and staggered with each other, and a corresponding separator is provided between each negative electrode coating part and the corresponding positive electrode coating part.

[0014] In a second aspect, an embodiment of the present application provides a cylindrical battery, which includes a shell and a pole piece assembly disposed inside the shell, wherein the pole piece assembly includes the above-mentioned pole piece assembly.

[0015] In a third aspect, an embodiment of the present application provides a battery module, wherein the battery module includes a plurality of batteries, and the batteries are configured as the above-mentioned cylindrical batteries.

[0016] In a fourth aspect, an embodiment of the present application further provides a battery pack, comprising a box body and a plurality of battery modules arranged inside the box body, wherein the battery modules are configured as the above-mentioned battery modules. Beneficial effects

[0017] The electrode assembly provided in the present application is achieved by arranging the electrode assembly inside the cylindrical battery into a plurality of negative electrode sheets, a plurality of diaphragms and a plurality of positive electrode sheets that are stacked and staggered with each other. Each negative electrode sheet includes a negative electrode coating portion and a negative electrode tab located outside the negative electrode coating portion, and each positive electrode sheet includes a positive electrode coating portion and a positive electrode tab located outside the positive electrode coating portion. Compared with the core structure, the current path of the core assembly is greatly affected by the height and radial dimensions of the battery, and each electrode sheet of the stacked electrode sheet assembly is provided with a pole tab, which is arranged on the outside of the electrode sheet. Therefore, the current path of each electrode sheet basically extends along the radial direction of the electrode sheet, thereby greatly reducing the internal resistance of the electrode sheet assembly inside the cylindrical battery, thereby improving the battery rate performance.

[0018] The cylindrical battery provided in this application is designed based on the above-mentioned pole piece assembly. Its beneficial effects can be found in the beneficial effects of the above-mentioned pole piece assembly, which will not be described in detail here.

[0019] The battery module provided in this application is designed based on the above-mentioned cylindrical battery. Its beneficial effects can be found in the beneficial effects of the above-mentioned cylindrical battery, which will not be described in detail here.

[0020] The battery pack provided in this application is designed based on the above-mentioned battery module. Its beneficial effects can be found in the beneficial effects of the above-mentioned battery module, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a schematic structural diagram of a battery provided in an embodiment of the present application;

[0022] FIG2 is a schematic diagram of a current path of a pole piece assembly in the related art;

[0023] FIG3 is a schematic structural diagram of a pole piece assembly provided in an embodiment of the present application;

[0024] FIG4 is a schematic structural diagram of a negative electrode sheet provided in an embodiment of the present application;

[0025] FIG5 is a schematic structural diagram of a positive electrode sheet provided in an embodiment of the present application;

[0026] FIG6 is a schematic structural diagram of a diaphragm provided in an embodiment of the present application;

[0027] FIG7 is a schematic cross-sectional view of a pole piece assembly unit according to an embodiment of the present application;

[0028] FIG8 is a perspective view of a single-layer diaphragm provided in an embodiment of the present application;

[0029] FIG9 is a partial enlarged view of FIG8;

[0030] FIG10 is a schematic top view of the structure of a pole piece assembly unit provided in an embodiment of the present application;

[0031] FIG11 is a schematic diagram of the stacked structure of a pole piece assembly provided in an embodiment of the present application;

[0032] FIG12 is a schematic diagram of the tab connection structure of the pole piece assembly provided in an embodiment of the present application;

[0033] FIG13 is a schematic top view of a tab connection structure of a pole piece assembly according to an embodiment of the present application;

[0034] FIG14 is a schematic diagram of the electrical connection structure of the output end of the pole piece assembly provided in an embodiment of the present application;

[0035] FIG15 is a schematic top view of the output terminal electrical connection structure of the electrode assembly provided in an embodiment of the present application;

[0036] FIG16 is a cross-sectional schematic diagram of an insulating film wrapped around a pole piece assembly according to an embodiment of the present application;

[0037] FIG17 is a schematic top view of an insulating film wrapped around a pole piece assembly according to an embodiment of the present application;

[0038] FIG18 is a schematic cross-sectional view of a battery according to the first embodiment of the present application;

[0039] FIG19 is a schematic diagram of a welding area of ​​a battery provided in the first embodiment of the present application;

[0040] FIG20 is a schematic diagram of the cross-sectional structure of a battery provided in a second embodiment of the present application;

[0041] FIG21 is a schematic cross-sectional view of a battery according to a third embodiment of the present application;

[0042] FIG22 is a schematic cross-sectional view of a battery according to a fourth embodiment of the present application;

[0043] Figure Number:

[0044] 1000, battery; 200, housing; 210, first side; 220, second side; 100, electrode assembly; 110, electrode assembly unit; 10, negative electrode; 11, negative electrode coating; 12, negative electrode tab; 121, first folding section; 122, first negative electrode tab; 123, first bending section; 124, second negative electrode tab; 125, seventh bending section; 20, positive electrode; 21, positive electrode coating; 22, positive electrode tab; 221, second folding section; 222, first positive electrode tab; 223, third bending section; 224, second positive electrode tab; 225 , fifth bending section; 31, first connecting member; 311, second bending section; 312, eighth bending section; 32, second connecting member; 321, fourth bending section; 322, sixth bending section; 40, diaphragm; 41, first diaphragm; 42, second diaphragm; 43, diaphragm substrate; 431, fiber skeleton; 44, solid electrolyte layer; 50, negative electrode adapter; 51, positive electrode insulator; 52, positive electrode adapter; 53, negative electrode insulator; 60, insulating film; 61, negative electrode welding area; 62, positive electrode welding area; 63, external negative electrode welding area; 64, external positive electrode welding area;

[0045] 300, cap assembly; 310, cover plate; 320, first negative electrode; 330, first electrode insulator; 340, first positive electrode; 400, bottom cover assembly; 410, bottom cover; 420, second positive electrode; 430, second electrode insulator; 440, second negative electrode; Modes for Carrying Out the Invention

[0046] In this application, unless otherwise specified, directional words such as "upper" and "lower" generally refer to the upper and lower parts of the device in actual use or working state, specifically the direction of the drawings in the accompanying drawings; while "inside" and "outside" refer to the outline of the device.

[0047] One embodiment of the present application provides a cylindrical battery 1000, as shown in Figure 1, the battery 1000 includes a shell 200, a pole piece assembly 100 and a cap assembly 300. The shell 200 is configured as a hollow cylindrical structure with one end open, the pole piece assembly 100 is arranged inside the shell 200, and the cap assembly 300 is used to seal the open end of the shell 200.

[0048] The models of cylindrical batteries can be set to 18650, 21700, 33145, 40135, 42300, 4680 and 46135. The relevant parameters of the above cylindrical batteries can be referred to as shown in Table 1 below:

[0049] Table 1. Cylindrical battery model parameter table

[0050] Battery model 1865021700331454013542300468046135 Pole piece assembly diameter D17.420.532.439.541.444.644.6 Pole piece width W636814013029576131W / D3.63.34.33.27.11.72.9

[0051] The cylindrical battery includes a core assembly, wherein the core assembly includes a positive electrode sheet, a negative electrode sheet and a separator arranged between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and the negative electrode sheet are respectively wound layer by layer to form the core assembly. A positive electrode tab is connected to one end of the positive electrode sheet, and a negative electrode tab is connected to one end of the negative electrode sheet. The positive electrode tab and the negative electrode tab are used to transmit current.

[0052] In order to improve the energy density and assembly efficiency of cylindrical batteries, the relevant technology mainly increases the size of cylindrical batteries. Large-sized cylindrical batteries often adopt a full-tab structure to further improve their rate performance.

[0053] For cylindrical batteries with a full-tab structure, the inner and outer rings of the positive and negative pole pieces usually need to be cut to leave space between the pole pieces. The purpose of this is to directly transmit current through the inner and outer ring current collectors. The current path in the area corresponding to the inner ring of the pole piece can refer to path I2 as shown in Figure 2, the current path in the area corresponding to the outer ring of the pole piece can refer to path I3 as shown in Figure 2, and the current path in the area where the pole piece tabs are located can refer to path I1 as shown in Figure 2.

[0054] The battery's core assembly is wound around a single electrode sheet. As the diameter of the battery 1000 increases, the length of the wound electrode sheet also increases accordingly. Because the electrode sheet is wound continuously, the resistance of each electrode sheet forms a series structure. In this series structure, the current in each electrode sheet passes through all parts of the electrode sheet, and the resistance is added up.

[0055] As battery height increases, the current path length in the core assembly also increases, leading to an increase in the length of the current path through the core (Path 1 shown in Figure 2), and thus an increase in resistance. Because the current needs to pass through the wound electrode sheets for the battery to function properly, the resistances along the electrode sheets that the current passes through are compounded, resulting in an increase in the core's internal resistance.

[0056] As the battery diameter increases, the circumference of the avoidance layer of the lower outer ring of the core assembly increases, which may cause the length of the tab portion to be cut off to increase, thereby increasing the length of path I3 as shown in Figure 2, indirectly leading to an increase in the internal resistance of the battery.

[0057] Therefore, as the battery size increases, the internal resistance of the cylindrical battery will increase, which in turn affects the battery rate performance.

[0058] In response to the problem of large internal resistance of the electrode assembly 100 in large-sized cylindrical batteries in the related art, a new structure of the electrode assembly 100 is provided in an embodiment of the present application. As shown in Figures 3 to 6, the electrode assembly 100 includes multiple negative electrode sheets 10, multiple separators 40 and multiple positive electrode sheets 20, and a separator 40 is arranged between each of the negative electrode sheets 10 and each of the positive electrode sheets 20, wherein the multiple negative electrode sheets 10, the multiple separators 40 and the multiple positive electrode sheets 20 are stacked, each of the negative electrode sheets 10 includes a negative electrode coating portion 11 and at least one negative electrode tab 12, and at least one of the negative electrode tabs 12 is located on the outside of the negative electrode coating portion 11, and each of the positive electrode sheets 20 includes a positive electrode coating portion 21 and at least one positive electrode tab 22, and at least one of the positive electrode tabs 22 is located on the outside of the positive electrode coating portion 21.

[0059] Among them, the number of negative electrode tabs 12 set on each negative electrode sheet 10 can be one, two, three or more; the number of positive electrode tabs 22 set on each positive electrode sheet 20 can be one, two, three or more. In a preferred embodiment, one negative electrode tab 12 is set on each negative electrode sheet 10, and one positive electrode tab 22 is set on each positive electrode sheet 20.

[0060] Compared with the related art in which the electrode assembly is wound along the central axis of the cylindrical battery, the current path of the winding core assembly will increase as the size of the battery increases. In the embodiment of the present application, the multiple negative electrode sheets 10, multiple separators 40 and multiple positive electrode sheets 20 of the electrode assembly 100 are stacked, each negative electrode sheet 10 is provided with at least one negative electrode tab 12, and each positive electrode sheet 20 is provided with at least one positive electrode tab 22, so that the current path of each negative electrode sheet 10 and each positive electrode sheet 20 extends along the radial direction of the electrode sheet, so that the current path of each electrode sheet is smaller than the inner diameter of the battery 1000. It can be seen from Table 1 that the height of the battery 1000 is significantly larger than the inner diameter of the battery 1000. Therefore, the current path of each electrode sheet in the embodiment of the present application is significantly reduced, and then the internal resistance of each electrode sheet is significantly reduced, so that the internal resistance of the electrode assembly 100 is significantly reduced, which is beneficial to improving the rate performance of the battery 1000.

[0061] Furthermore, by stacking the pole pieces of the pole piece assembly 100 along the longitudinal axis of the pole piece assembly 100, there is no need to design a center hole inside the pole piece assembly 100, so that the pole piece assembly 100 can maximize the internal space of the battery housing 200, thereby facilitating an increase in the volume of the battery 1000. The longitudinal axis of the pole piece assembly 100 is the Y direction as shown in FIG3 . In a cylindrical battery, the longitudinal axis of the pole piece assembly 100 is consistent with the height direction of the battery.

[0062] As shown in FIG7 , the electrode assembly 100 includes a plurality of stacked electrode assembly units 110, which are stacked along the longitudinal axis of the electrode assembly 100. Each electrode assembly unit 110 includes a first separator 41, a negative electrode sheet 10, a second separator 42, and a positive electrode sheet 20, which are stacked in sequence. A complete electrode assembly unit 110 is formed by using a layer of separator 40, a layer of negative electrode sheet 10, a layer of positive electrode sheet 20, and a layer of separator 40. The stacking design is based on the height of the battery 1000 and the total thickness T0 of the electrode assembly unit 110, without a center hole design, thereby more effectively utilizing the internal space of the cylindrical battery 1000.

[0063] The negative electrode sheet 10 includes a negative electrode substrate, a portion of the outer surface of the negative electrode substrate is coated with a negative electrode active material to form a negative electrode coating portion 11 , and a portion of the outer surface of the negative electrode substrate is not coated with a negative electrode active material to form a negative electrode tab 12 .

[0064] The negative electrode substrate refers to a thin sheet-like substrate used to accommodate the negative electrode active material in the battery 1000. Its function is to provide support and conductivity. Suitable negative electrode substrates include copper foil, aluminum foil, stainless steel mesh, titanium foil, etc.

[0065] Negative electrode active materials usually include graphite, silicon, metal oxides, carbon materials and alloy materials. Suitable metal oxides include titanium dioxide (TiO2), ferric oxide (Fe2O3), etc., suitable carbon materials include hard carbon, soft carbon, carbon black, etc., and suitable alloy materials include lithium alloys, such as lithiated aluminum, lithiated silicon, etc.

[0066] The positive electrode sheet 20 includes a positive electrode substrate, a portion of the outer surface of the positive electrode substrate is coated with a positive electrode active material to form a positive electrode coating portion 21 , and a portion of the outer surface of the positive electrode substrate is not coated with a positive electrode active material to form a positive electrode tab 22 .

[0067] The positive electrode substrate refers to a thin sheet-like substrate used to accommodate the positive electrode active material in the battery 1000. The positive electrode substrate is used to provide support and conductivity. Suitable positive electrode substrates include aluminum foil, stainless steel mesh, copper foil, etc.

[0068] Positive electrode active materials generally include metal oxides, phosphates, and sulfides. Suitable metal oxides include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), etc. Suitable phosphates include lithium iron phosphate (LiFePO4), and suitable sulfides include cadmium sulfide (CdS), copper sulfide (Cu2S), etc.

[0069] The material of the diaphragm 40 is generally made of polymer or ceramic material. Suitable polymer materials include polychromate (PVdF), polyvinyl alcohol (PVA), and polyvinyl glucose (PEG). Suitable ceramic materials include aluminum oxide (Al2O3) and lithium phosphate (Li3PO4).

[0070] As shown in Figures 8 and 9, the battery 1000 is configured as a solid electrolyte battery. The battery 1000 can only be activated, formed, and divided into different volumes after being packaged. The diaphragm 40 includes a diaphragm substrate 43 and a solid electrolyte layer 44 coated on two opposite planes of the diaphragm substrate 43. The diaphragm substrate 43 includes a plurality of fiber skeletons 431. The solid electrolyte can be further filled in the fiber skeleton 431. The solid electrolyte can be formed by ion conductive materials such as ceramics, polymers, or composite materials, and has high ion conductivity. Since the solid electrolyte does not contain organic solvents, it can greatly reduce safety hazards such as electrolyte leakage, combustion, and expansion. Therefore, the solid electrolyte has higher electrochemical stability and longer cycle life than the liquid electrolyte.

[0071] The thickness JT of the diaphragm substrate 43 is set to 6 μm to 20 μm, and the ratio of the thickness dt of the solid electrolyte layer 44 to the thickness JT of the diaphragm substrate 43 is 1 / 20 to 1 / 2. In a specific embodiment, the thickness JT of the diaphragm substrate 43 can be set to 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, or a value between any two of the above values, or a range between any two of the above values. The ratio of the thickness dt of the solid electrolyte layer 44 to the thickness JT of the diaphragm substrate 43 can be 1 / 18, 1 / 16, 1 / 14, 1 / 12, 1 / 10, 1 / 8, 1 / 6, 1 / 4, or a value between any two of the above values, or a range between any two of the above values. When the thickness JT of the diaphragm substrate 43 is set to greater than 20 μm, it is not conducive to the lightweight design of the entire electrode assembly 100. When the thickness JT of the diaphragm substrate 43 is set to less than 6 μm, the overall mechanical strength of the diaphragm 40 is insufficient, thereby affecting the stability and service life of the diaphragm 40.

[0072] As shown in Figures 4, 5, and 10, the negative electrode coating portion 11 is configured as a circular coating portion with a diameter of φA. The positive electrode coating portion 21 is configured as a circular coating portion with a diameter of φB, where φA is greater than φB. Taking a lithium-ion battery 1000 as an example, lithium-ion batteries 1000 are subject to lithium deposition. The diameter of the negative electrode coating portion 11 is configured to be larger than the diameter of the positive electrode coating portion 21. The excess portion of the negative electrode coating portion 11 beyond the positive electrode coating portion 21 is used to prevent lithium branch crystals from precipitating and potentially piercing the separator 40.

[0073] In a preferred embodiment, the diameter φA of the negative electrode coating portion 11 exceeds the diameter φB of the positive electrode coating portion 21 to meet the following requirements: the difference between φA and φB is not less than 0.3 mm, and the difference between φA and φB is not greater than 1 mm. It is understood that the difference between φA and φB can be 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or a value or range between any two of the above values.

[0074] Considering that keeping the negative electrode coating portion 11 and the positive electrode coating portion 21 aligned is beneficial to improving the performance of the battery 1000, the negative electrode plate 10 and the positive electrode plate 20 are formed by equipment stacking, and there is a certain positioning deviation during the stacking process, so the difference between φA and φB is not less than 0.3mm. At the same time, considering that when the battery 1000 is set as a solid electrolyte lithium-ion battery, the channel range of the lithium ions in the solid electrolyte layer 44 is not easy to diffuse outward relative to the liquid electrolyte, so the difference between φA and φB is not greater than 1mm.

[0075] As shown in FIG6 , the separator 40 is configured as a circular separator 40 , and the diameter of the separator 40 is configured as φC, where φB≤φC≤φA. In one example, the diameter of the separator 40 is substantially equal to the diameter of the negative electrode plate 10 , thereby facilitating that the separator 40 completely covers the negative electrode coating portion 11 of the negative electrode plate 10 .

[0076] Further referring to Figures 4, 5, and 10, the negative electrode tab 12 or the positive electrode tab 22 is configured as a sector-shaped piece disposed on one side of the circular coating portion. The arc length of the sector-shaped piece is L, and the calculation formula for L is R×π×(α / 180°), where R is the radius of the circular electrode piece, and α is the angle formed by the line connecting the two ends of the sector-shaped piece and the center of the circular electrode piece. α is set to 10° to 60°. It can be understood that when the positive electrode tab 22 or the negative electrode tab 12 is within the above-mentioned central angle range of the circular electrode piece, it is convenient to fold the positive electrode tab 22 or the negative electrode tab 12. In some specific embodiments, α is set to 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, or any value or range between any two of the above values.

[0077] The area of ​​the circular coating is 2×π×R 2 The arc length L of the tab is R×π×(α / 180°). After research, the inventors found that when α is set to 10°~60°, it is beneficial to balance the bending effect of the tab, the effective current collecting area of ​​the tab, and the internal resistance design requirements of the pole piece assembly. When α is set to less than 10°, the arc length L of the tab is less than R×π×(1 / 18), and the corresponding current collecting capacity of the tab does not meet the design requirements of the internal resistance of the pole piece assembly. When α is set to greater than 60°, the arc length L of the tab is greater than R×π×(1 / 3), and the width corresponding to the arc length of the tab is wider. The tab is prone to cracking when bending, which in turn affects the current collecting capacity of the tab and makes it difficult to meet the subsequent welding requirements of the tab.

[0078] Among them, the angle formed by the line connecting the two ends of the sector-shaped piece where the negative electrode tab 12 is located and the center of the negative electrode circular coating portion is α1, and the angle formed by the line connecting the two ends of the sector-shaped piece where the positive electrode tab 22 is located and the center of the positive electrode circular coating portion is α2. In some embodiments, α1 and α2 are set to be the same, and in some optional embodiments, α1 and α2 are set to be different.

[0079] As shown in Figure 10, the projection surface of the negative electrode tab 12 on the radial cross-section of the electrode assembly 100 is located on one side of the central axis of the circular coating portion, and the projection surface of the positive electrode tab 22 on the radial cross-section of the electrode assembly 100 is located on the other side of the central axis of the circular coating portion. The projection surface of the negative electrode tab 12 on the radial cross-section of the electrode assembly 100 and the projection surface of the positive electrode tab 22 on the radial cross-section of the electrode assembly 100 are symmetrically arranged with respect to the center of the circular coating portion. In other optional embodiments, the projection surface of the negative electrode tab 12 on the radial cross-section of the electrode assembly 100 and the projection surface of the positive electrode tab 22 on the radial cross-section of the electrode assembly 100 are asymmetrically arranged with respect to the center of the circular coating portion.

[0080] Further referring to FIG7 , the negative electrode tab 12 includes a first folding section 121. The first folding section 121 is configured to be formed by folding the negative electrode tab 12. A folding angle β is formed between the first folding section 121 and the longitudinal axis of the electrode assembly 100. β is set to be 3° to 10°. When the folding angle β of the negative electrode tab 12 is within this range, it is convenient to stack and connect multiple negative electrode tabs 12 in parallel. In specific implementations, β can be 4°, 5°, 6°, 7°, 8°, 9°, or a value or range between any two of the above values.

[0081] The positive electrode tab 22 includes a second folding section 221, which is configured to fold the positive electrode tab 22. The positive electrode tab 22 forms a folding angle γ with the longitudinal axis of the electrode assembly 100. The folding angle γ is set to 3° to 10°. When the folding angle γ of the positive electrode tab 22 is within the above range, it is convenient to stack and connect multiple positive electrode tabs 22 in parallel. In a specific implementation, γ can be 4°, 5°, 6°, 7°, 8°, 9°, or a value or range between any two of the above values.

[0082] After research, the inventors found that taking into account the convenience of stacking multiple electrode group units 110 and the ease of shaping the electrode ears after stacking, and the fact that the shaped electrode ears are conducive to welding and current collection with components such as collecting plates, the folding angle β of the negative electrode ear 12 is set to 3°~10°, and the folding angle γ of the positive electrode ear 22 is set to 3°~10°.

[0083] The folding angle β of the negative electrode tab 12 and the folding angle γ of the positive electrode tab 22 may be set to be the same, or the folding angle β of the negative electrode tab 12 and the folding angle γ of the positive electrode tab 22 may be set to be different.

[0084] Further referring to Figure 7, the total thickness of the electrode assembly unit 110 is T0, and the total thickness T0 of the electrode assembly unit 110 includes the sum of the thickness of the first diaphragm 41, the thickness of the negative electrode plate 10, the thickness of the second diaphragm 42 and the thickness of the positive electrode plate 20, 0.2mm≤T0≤1mm. When T0 is within the above range, it is beneficial to set up multiple stacked electrode assembly units 110 inside the battery 1000, so that the battery 1000 has suitable capacity and charge and discharge performance. In a specific implementation, T0 can be set to any value or range between 0.2 mm and 1 mm based on the material of the diaphragm 40 used in the battery 1000, the substrate material of the negative electrode plate 10, the substrate material of the positive electrode plate 20, the compaction density of the negative electrode active material, and the compaction density of the positive electrode active material. For example, T0 can be 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and a value between any two of the above values ​​or a range between any two of the above values.

[0085] Through research, the inventors discovered that when battery 1000 is configured as a solid-state lithium-ion battery, the positive electrode sheet 20 of the lithium-ion battery provides lithium ions, while the negative electrode sheet 10 provides a conductive carbon layer structure. To ensure that lithium ions are fully absorbed and embedded in the carbon layer structure of the negative electrode sheet 10 during the charge and discharge process, the negative electrode sheet 10's loading capacity must be greater than the inherent lithium ion capacity of the positive electrode sheet 20. Furthermore, the conductive carbon layer structure of the negative electrode sheet 10 is relatively loose, so the thickness of the negative electrode sheet 10 is greater than that of the positive electrode sheet 20.

[0086] Furthermore, through studying different total thicknesses T0 of the electrode assembly units 110 , it was found that when the total thickness T0 of the electrode assembly units 110 is set to 0.20 mm to 0.5 mm, it is beneficial to maintain the discharge rate capability of the battery 1000 .

[0087] Table 1 Comparison of the thickness of each layer of the electrode assembly unit and the battery discharge rate performance

[0088] No. Positive electrode sheet thickness / mm Negative electrode sheet thickness / mm Diaphragm thickness / mm T0 Total thickness / mm Discharge rate capability 10.08~0.10 0.11~0.13 0.012 0.21 4~0.25 4 20C and above 20.11~0.15 0.16~0.19 0.012 0.29 4~0.36 4 1C~6C 30.16~0.19 0.20~0.28 0.012 0.38 4~0.49 4 1C~6C

[0089] From the data in Table 1, it can be found that the thickness of the positive electrode sheet 20 in the electrode sheet assembly unit 110 is 0.08mm~0.20mm, the thickness of the negative electrode sheet 10 is 0.1mm~0.3mm, and the thickness of the separator 40 is less than the thickness of the positive electrode sheet 20 and less than the thickness of the negative electrode sheet 10.

[0090] As shown in Figure 11, the negative electrode tab 12 includes a first folding segment 121, and the length of the first folding segment 121 is L1, 2T0≤L1≤10T0. It can be understood that the ratio of the length L1 of the first folding segment 121 to the thickness T0 of the electrode group unit 110 can be any value between 2 and 10, for example, the ratio of the length L1 of the first folding segment 121 to the thickness T0 of the electrode group unit 110 is 3, 4, 5, 6, 7, 8, 9, and a value between any two of the above values ​​or a range between any two of the above values.

[0091] The positive electrode tab 22 includes a second folded section 221. The length of the second folded section 221 is L2, and 2T0≤L2≤10T0. The ratio of the length L2 of the second folded section 221 to the thickness T0 of the electrode assembly unit 110 can be any value between 2 and 10. For example, the ratio of the length L2 of the second folded section 221 to the thickness T0 of the electrode assembly unit 110 is 3, 4, 5, 6, 7, 8, 9, or a value or range between any two of the above values.

[0092] When the folding angle β of the first folding segment 121 of multiple negative electrode tabs 12 and the length L1 of the first folding segment 121 meet the above requirements, the multiple negative electrode tabs 12 can be arranged on one side of the electrode assembly 100 with a uniform stacking density and conveniently shape and weld the multiple negative electrode tabs 12. When the folding angle γ of the second folding segment 221 of multiple positive electrode tabs 22 and the length L2 of the second folding segment 221 meet the above requirements, the multiple positive electrode tabs 22 can be arranged on the other side of the electrode assembly 100 with a uniform stacking density and conveniently shape and weld the multiple positive electrode tabs 22.

[0093] Referring to Figures 12 to 15, in some embodiments provided in the present application, the electrode assembly 100 includes N electrode group units 110, and the N electrode group units 110 include N negative electrode tabs 12 and N positive electrode tabs 22. The electrode assembly 100 also includes a first connector 31 and a second connector 32, wherein the first connector 31 is used to connect at least N negative electrode tabs 12, and the second connector 32 is used to connect at least N positive electrode tabs 22, wherein the first connector 31 and the second connector 32 are arranged at intervals.

[0094] The first connector 31 is used to weld the bent and stacked multiple negative electrode tabs 12 to form a unified current collecting channel, and the second connector 32 is used to weld the bent and stacked multiple positive electrode tabs 22 to form a unified current collecting channel. Furthermore, two adjacent electrode assembly units 110 are connected in parallel via the first connector 31 and the second connector 32, thereby further reducing the internal resistance of the electrode assembly 100.

[0095] By optimizing the folding direction, folding angle and folding length of the N negative electrode tabs 12, the orthographic projections of the N negative electrode tabs 12 along the longitudinal axis of the electrode assembly 100 are located on the first connecting member 31, thereby enabling the N negative electrode tabs 12 to be connected to the first connecting member 31. By optimizing the folding direction, folding angle and folding length of the N positive electrode tabs 22, the orthographic projections of the N positive electrode tabs 22 along the longitudinal axis of the electrode assembly 100 are located on the second connecting member 32, thereby enabling the N positive electrode tabs 22 to be connected to the second connecting member 32.

[0096] Further referring to Figure 13, the thickness of the first connecting member 31 is T1, wherein the thickness T1 of the first connecting member 31 is set to the projection distance of the first connecting member 31 on the radial section of the pole piece assembly 100, 0.08mm≤T1≤0.15mm; and / or, the thickness of the second connecting member 32 is T2, 0.10mm≤T2≤0.25mm, and the thickness T2 of the second connecting member 32 is set to the projection distance of the second connecting member 32 on the radial section of the pole piece assembly 100.

[0097] In a specific embodiment, the thickness T1 of the first connecting member 31 can be 0.09 mm, 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, and a value between any two of the above values, or a range between any two of the above values; the thickness T2 of the second connecting member 32 can be 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.23 mm, and a value between any two of the above values, or a range between any two of the above values.

[0098] The primary function of the first connector 31 and the second connector 32 is to weld and connect the stacked multiple negative electrode tabs 12 and the multiple positive electrode tabs 22 to form a unified current path. The thickness T1 of the first connector 31 satisfies 0.08 mm ≤ T1 ≤ 0.15 mm. The inventors have discovered that when the thickness T1 of the first connector 31 is less than 0.08 mm, the battery 1000 has insufficient current capacity and cannot meet discharge rates above 6C. Multiple negative electrode tabs are welded to the first connector 31. During welding, a high-energy arc or laser is generally used to instantaneously heat the tabs and the first connector 31 to form a welding point between the tabs and the first connector. When the thickness T1 of the first connector 31 is greater than 0.15 mm, the increase in the thickness of the first connector 31 will cause the heat transfer speed to slow down, and the heat of welding is difficult to dissipate quickly, causing the local temperature near the tab to rise. When the welding temperature exceeds the melting point of the tab, the tab will melt through, which will cause the current collecting capacity of the battery 1000 to decrease, and thus the 6C overcurrent capacity requirement cannot be met.

[0099] The thickness T2 of the second connector 32 satisfies 0.10mm≤T2≤0.25mm. Similarly, when the thickness T2 of the second connector 32 is less than 0.10mm, the battery 1000's current handling capacity is insufficient and cannot meet the battery's discharge rate requirements of 6C or higher. Multiple positive electrode tabs are welded to the second connector 32. When the thickness T2 of the second connector 32 is greater than 0.25mm, the increased thickness of the second connector 32 slows down heat transfer, making it difficult for welding heat to dissipate quickly, causing localized temperature increases near the tabs. When the welding temperature exceeds the melting point of the tabs, the tabs can melt through, further reducing the battery 1000's current collecting capacity and failing to meet the 6C current handling capacity requirement.

[0100] The thickness of the negative electrode tab 12 is t1, 0.02mm≤t1≤0.1mm, and the thickness of the positive electrode tab 22 is t2, t2≤0.2mm, wherein the thickness t1 of the negative electrode tab 12 is set to the projected distance of the negative electrode tab 12 on the radial cross-section of the electrode assembly 100, and the thickness t2 of the positive electrode tab 22 is set to the projected distance of the positive electrode tab 22 on the radial cross-section of the electrode assembly 100. The thickness t1 of the negative electrode tab 12 can be 0.02mm, 0.05mm, 0.08mm, 0.1mm, or a value between any two of the above values, or a range between any two of the above values. The thickness t2 of the positive electrode tab 22 can be 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, or a value between any two of the above values, or a range between any two of the above values.

[0101] The materials of the first connector 31 and the second connector 32 may be different depending on the type of battery 1000 to which they are applied. For example, when the cylindrical battery 1000 is a lithium-ion battery 1000 or a lithium carbonate battery 1000, the material of the first connector 31 is copper, and the material of the second connector 32 is aluminum or copper. When the cylindrical battery 1000 is a sodium-ion battery 1000, the material of the first connector 31 is copper, and the material of the second connector 32 is nickel or cobalt.

[0102] The first connector 31 is configured to cover all of the negative electrode tabs 12. The negative electrode tabs 12 are configured as fan-shaped sheet structures. Correspondingly, the first connector 31 is configured as an arc-shaped structure. The circumference of the first connector 31 is greater than the circumference of the negative electrode tab 12. Specifically, the circumference of the arc of the first connector 31 exceeds the circumference of the fan-shaped section of the negative electrode tab 12 by 0.5 mm to 1 mm, allowing the first connector 31 to surround the negative electrode tab 12. The circumference of the arc of the first connector 31 exceeding the circumference of the fan-shaped section of the negative electrode tab 12 by 0.5 mm to 1 mm facilitates the electrical connection of multiple negative electrode tabs 12 to the first connector 31 via laser welding, and the first connector 31 can cover the negative electrode tab 12.

[0103] Correspondingly, the second connector 32 is configured to cover all the positive electrode tabs 22. The positive electrode tabs 22 are configured as fan-shaped sheet structures, and the second connector 32 is configured as an arc-shaped structure. The circumference of the second connector 32 is greater than the circumference of the positive electrode tab 22. Specifically, the circumference of the arc where the second connector 32 is located exceeds the circumference of the fan-shaped where the positive electrode tab 22 is located by 0.5mm~1mm, so that the second connector 32 can be arranged to surround the positive electrode tab 22. Among them, the circumference of the arc where the second connector 32 is located exceeds the circumference of the fan-shaped where the positive electrode tab 22 is located by 0.5mm~1mm, which facilitates the electrical connection of multiple positive electrode tabs 22 to the second connector 32 by laser welding, and the second connector 32 can cover the positive electrode tab 22.

[0104] Further referring to FIG12 , the N negative electrode tabs 12 and the N positive electrode tabs 22 are configured to be folded in a first direction; alternatively, one of the N negative electrode tabs 12 and the N positive electrode tabs 22 is configured to be folded in the first direction, and the other of the N negative electrode tabs 12 and the N positive electrode tabs 22 is configured to be folded in a second direction, wherein the second direction and the first direction are set to be opposite directions. In a specific implementation, the first direction can be set to be a direction toward the cap assembly 300 of the cylindrical battery 1000, and correspondingly, the second direction is set to be a direction away from the cap assembly 300. Alternatively, the first direction can also be set to be a direction away from the cap assembly 300, and correspondingly, the second direction is set to be a direction toward the cap assembly 300.

[0105] By setting the folding directions of all the negative electrode tabs 12 and the folding directions of the positive electrode tabs 22 , all the negative electrode tabs 12 are connected to the first connector 31 in an orderly manner, and all the positive electrode tabs 22 are connected to the second connector 32 in an orderly manner.

[0106] As shown in Figures 14 to 22, the electrode assembly 100 includes N electrode group units 110, each of the electrode group units 110 includes a negative electrode tab 12 and a positive electrode tab 22, and the electrode assembly 100 also includes a first connector 31 and a second connector 32, the first connector 31 is used to connect the N negative electrode tabs 12, and the second connector 32 is used to connect the N positive electrode tabs 22, wherein the first connector 31 and the second connector 32 are arranged at intervals, so that a safety interval is formed between the first connector 31 and the second connector 32, thereby preventing a short circuit from forming inside the battery.

[0107] In a preferred embodiment, the housing 200 of the cylindrical battery 1000 includes a first side 210 and a second side 220 disposed opposite each other. The first connector 31 is disposed proximate to the first side 210, and the second connector 32 is disposed proximate to the second side 220. By disposing the first connector 31 and the second connector 32 on either side of the cylindrical battery 1000, respectively, it is convenient to fold the multiple negative electrode tabs 12 in one direction and then weld them to the first connector 31, and to fold the multiple positive electrode tabs 22 in one direction and then weld them to the second connector 32. This allows for the formation of unified current collecting channels on both sides of the cylindrical battery 1000, and improves the efficiency of tab shaping and welding.

[0108] The battery 1000 also includes a cap assembly 300, which includes a cover plate 310, an electrode post, and a post insulator. An electrical connection structure is provided between the electrode assembly 100 and the electrode post. In one embodiment, as shown in FIG18 , a first negative electrode post 320 is provided on the cap assembly 300, and a first post insulator 330 is provided between the first negative electrode post 320 and the cover plate 310. The first negative electrode post 320 is further electrically connected to the negative output terminal of the electrode assembly 100 via a negative electrode adapter 50, wherein the negative electrode adapter 50 is provided between the first negative electrode post 320 and the first connector 31. The negative electrode adapter 50 is not only used to transmit current, but also used to improve the current collection capacity of the battery 1000. The negative electrode adapter 50 can be made of the same conductive metal material as the first connector 31, and the thickness of the negative electrode adapter 50 is set to be greater than the thickness of the first connector 31.

[0109] The shell 200 is electrically connected to the positive output terminal of the pole piece assembly 100, and the top surface of the pole piece assembly 100 is also provided with a positive pole insulating member 51 and the above-mentioned negative pole adapter plate 50, wherein the positive pole insulating member 51 is arranged close to the negative pole adapter plate 50, and the positive pole insulating member 51 is in contact with the negative pole adapter plate 50 or a gap is provided between the positive pole insulating member 51 and the negative pole adapter plate 50, and the positive pole insulating member 51 is used to prevent a short circuit connection between the negative output terminal and the positive output terminal of the pole piece assembly 100.

[0110] In other optional embodiments, as shown in Figure 20, a first positive pole column 340 is provided on the cap assembly 300, and the first positive pole column 340 is further electrically connected to the positive output end of the pole piece assembly 100 through the positive adapter plate 52, and the shell 200 is electrically connected to the negative output end of the pole piece assembly 100, and a negative pole insulating member 53 and the above-mentioned positive pole adapter plate 52 are provided on the top surface of the pole piece assembly 100, wherein the negative pole insulating member 53 is provided close to the positive adapter plate 52, and the negative pole insulating member 53 is in contact with the positive adapter plate 52 or a gap is provided between the negative pole insulating member 53 and the positive adapter plate 52, and the negative pole insulating member 53 is used to prevent a short circuit connection between the positive output end and the negative output end of the pole piece assembly 100.

[0111] Continuing to refer to Figures 15 to 20, the electrode assembly 100 includes a first negative electrode tab 122 and a first positive electrode tab 222 arranged near the cap assembly 300, wherein the first negative electrode tab 122 includes a first bending section 123, and the first connecting member 31 includes a second bending section 311, the second bending section 311, the first bending section 123 and the negative electrode adapter 50 are electrically connected in sequence and stacked on the top surface of the electrode assembly 100, the length of the first bending section 123 is not greater than the length H1 of the second bending section 311, and the length H1 of the second bending section 311 is less than the length B1 of the negative electrode adapter 50.

[0112] The first positive electrode tab 222 includes a third bending section 223, and the second connecting member 32 includes a fourth bending section 321. The fourth bending section 321, the third bending section 223 and the positive electrode insulating member 51 are connected in sequence and stacked on the top surface of the electrode assembly 100. The length of the third bending section 223 is not greater than the length of the fourth bending section 321, and the length H2 of the fourth bending section 321 is less than the length A2 of the positive electrode insulating member 51.

[0113] Among them, the negative electrode adapter plate 50 and the second bent section 311 of the first connector 31 are welded to achieve electrical connection. The welding area between the negative electrode adapter plate 50 and the first connector 31 is mainly affected by the length B1 of the negative electrode adapter plate 50 and the length H1 of the second bent section 311. The welding area between the negative electrode adapter plate 50 and the first connector 31 further determines the current capacity of the battery 1000.

[0114] Furthermore, the fourth bend section 321 of the second connector 32 is welded to the cover plate 310 to achieve electrical connection. The weld area between the cover plate 310 and the second connector 32 is primarily influenced by the length H2 of the fourth bend section 321 of the second connector 32. This weld area further determines the current handling capacity of the battery 1000. The inventors have discovered that when H1 satisfies the following conditions: R1 / 3 ≤ H1 ≤ R1 / 2, H2 satisfies the following conditions: R1 / 3 ≤ H2 ≤ R1 / 2, and B1 satisfies the following conditions: R1 ≤ B1 ≤ 3R1 / 2, this helps reduce the internal resistance of the battery 1000, thereby improving its current handling capacity. Specific experimental data can be found in Table 3 below.

[0115] Table 3 Performance impact of H1, H2, and B1 on battery internal resistance

[0116] Serial number H1 (1 / 3R1~1 / 2R1) H2 (1 / 3R1~1 / 2R1) B1 (R1~3R1 / 2) Battery internal resistance (@30%SOC, DCIR) 1<1 / 3R1<1 / 3R1<R1>3mΩ 2(1 / 3R1~1 / 2R1)<1 / 3R1<R1>3mΩ 3<1 / 3R1(1 / 3R1~1 / 2R1)<R1>3mΩ 4<1 / 3R1<1 / 3R1>3R1 / 2>2mΩ 5(1 / 3R1~1 / 2R1)<1 / 3R1>3R1 / 2>2mΩ 6<1 / 3R1 (1 / 3R1~1 / 2R1)>3R1 / 2>2mΩ71 / 3R1~1 / 2R11 / 3R1~1 / 2R1R~3R1 / 20.5~1.0mΩ8>1 / 2R1<1 / 3R1<R1>3mΩ9>1 / 2R1<1 / 3R1>3R1 / 2>1mΩ10>1 / 2R1>1 / 2R1<R1>3mΩ11>1 / 2R1>1 / 2R1>3R1 / 2Cannot be implemented, positive and negative poles are short-circuited

[0117] By analyzing the data in the above table, it is found that, as shown in the data of serial number 7, when and only when H1 satisfies R1 / 3≤H1≤R1 / 2, H2 satisfies R1 / 3≤H2≤R1 / 2, and B1 satisfies R1≤B1≤3R1 / 2, the DC internal resistance of the battery 1000 is measured to be 0.5mΩ~1.0mΩ in the charge and discharge state with a power of 30%. When the value of any one of H1, H2, and B1 is outside the above range, as shown in the data of serial numbers 1, 2, 3, 4, 5, 6, 8, 9, and 10, the DC internal resistance of the battery 1000 is greater than 1mΩ in the charge and discharge state with a power of 30%. When H1 is greater than R1 / 2, H2 is greater than R1 / 2, and B1 is greater than 3R1 / 2, the positive and negative poles of the battery 1000 will be short-circuited, making it impossible to implement.

[0118] Furthermore, the first bend section 123 and the second bend section 311 have substantially the same length, so that the first connector 31 can completely cover the first negative electrode tab 122. The first bend section 123 and the second bend section 311 are both arranged perpendicular to the longitudinal axis of the battery 1000. The third bend section 223 and the fourth bend section 321 have substantially the same length, so that the second connector 32 can completely cover the first positive electrode tab 222. The third bend section 223 and the fourth bend section 321 are both arranged perpendicular to the longitudinal axis of the battery 1000.

[0119] In alternative embodiments, a first negative electrode post 320 and a first positive electrode post 340 may also be provided on the cap assembly 300. The first positive electrode post 340 is electrically connected to the second connector 32 via the positive electrode adapter 52. The first negative electrode post 320 is preferably a copper-aluminum composite post, and the first positive electrode post 340 is preferably an aluminum post.

[0120] In another embodiment provided in the present application, as shown in FIG21, a cap assembly 300 is provided at the top end of the shell 200, a bottom cover assembly 400 is provided at the bottom end of the shell 200, a first negative electrode 320 is provided on the cap assembly 300, a second positive electrode 420 is provided on the bottom cover assembly 400, the negative output end of the pole piece assembly 100 is electrically connected to the first negative electrode 320 provided on the cap assembly 300, the bottom cover assembly 400 includes a bottom cover 410, a second positive electrode 420 and a second electrode insulating member 430 provided between the bottom cover 410 and the second positive electrode 420, the positive output end of the pole piece assembly 100 is electrically connected to the second positive electrode 420, wherein the negative output end of the pole piece assembly 100 is electrically connected to the negative electrode The electrical connection method of 320 is the same as that of the above embodiment. The cylindrical battery 1000 also includes a positive electrode adapter plate 52 located at the bottom end of the electrode assembly 100. The electrode assembly 100 includes a second positive electrode ear 224 located at the bottom end of the electrode assembly 100. The second positive electrode ear 224 includes a fifth bending section 225. The second connecting member 32 includes a sixth bending section 322. The sixth bending section 322, the fifth bending section 225 and the positive electrode adapter plate 52 are electrically connected in sequence and stacked on the bottom end surface of the electrode assembly 100. The length of the fifth bending section 225 is not greater than the length of the sixth bending section 322, and the length of the sixth bending section 322 is less than the length of the positive electrode adapter plate 52.

[0121] In another embodiment provided in the present application, as shown in Figure 22, a first positive electrode post 340 is provided on the cap assembly 300, and a second negative electrode post 440 is provided on the bottom cover assembly 400. The positive output end of the electrode assembly 100 is electrically connected to the first positive electrode post 340 provided on the cap assembly 300, and a positive electrode adapter 52 is provided on the top surface of the electrode assembly 100. The first positive electrode ear 222 includes a third bending section 223, and the second connecting member 32 includes a fourth bending section 321. The fourth bending section 321, the third bending section 223 and the positive electrode adapter 52 are electrically connected in sequence and stacked on the top surface of the electrode assembly 100; and / or,

[0122] A negative electrode adapter plate 50 is provided on the bottom end surface of the electrode assembly 100, and the electrode assembly 100 includes a second negative electrode tab 124 located at the bottom end of the electrode assembly 100, and the second negative electrode tab 124 includes a seventh bending section 125, and the first connecting member 31 includes an eighth bending section 312, and the eighth bending section 312, the seventh bending section 125 and the negative electrode adapter plate 50 are electrically connected in sequence and stacked on the bottom end surface of the electrode assembly 100.

[0123] Furthermore, the welding area between the second connector 32 and the positive electrode adapter plate 52 affects the current collection capacity of the battery 1000, and the welding area between the second connector 32 and the positive electrode adapter plate 52 is mainly affected by the length of the sixth bending section 322 of the second connector 32 and the length of the positive electrode adapter plate 52. The length of the sixth bending section 322 is set between R1 / 3 and R1 / 2, and the length of the positive electrode adapter plate 52 is set between R~3R1 / 2, which is beneficial to improving the current collection capacity of the battery 1000.

[0124] With further reference to Figures 16 and 17 , battery 1000 further includes an insulating film 60, which is used to insulate the periphery of the pole piece assembly. The insulating film 60 comprises at least two portions: one portion is disposed between the first connector 31 and the housing 200, and the other portion is disposed between the second connector 32 and the housing 200. As shown in Figure 17 , in a preferred embodiment, the insulating film 60 covers the entire periphery of the pole piece assembly.

[0125] Materials suitable for preparing the insulating film 60 include polyimide (PI) and polypropylene (PP). The insulating film 60 and the pole piece assembly are bonded by an adhesive, so that the insulating film 60 and the pole piece assembly can fit tightly.

[0126] Further referring to FIG. 19 , the negative electrode welding region 61 of the cylindrical battery 1000 is located in the center of the cylindrical battery 1000. The negative electrode welding region 61 is configured to sequentially electrically connect the negative electrode tab 10, the first connector 31, and the negative electrode adapter 50. The positive electrode welding region 62 of the cylindrical battery 1000 is located near one side of the cylindrical battery 1000. The positive electrode welding region 62 is configured to sequentially electrically connect the positive electrode tab 20 and the second connector 32. The cross-section of the negative electrode welding region 61 is generally circular, while the positive electrode welding region 62 is generally fan-shaped.

[0127] The negative electrode adapter 50 is primarily used to achieve external electrical connections for the battery 1000. Its thickness is set between 0.8 and 1.2 times the thickness of the external welding layer, which is set to 0.6 mm to 1.0 mm. The thickness of the positive electrode insulator 51 primarily meets assembly requirements, ensuring welding and positioning between the tab area of ​​the electrode assembly 100 and the external output terminal of the battery. The thickness of the positive electrode insulator 51 can be set to 0.8 mm to 1.5 mm as needed.

[0128] The battery module includes multiple cylindrical batteries 1000, which are arranged in series, parallel, or mixed to meet the capacity requirements of the battery module. The cap assembly 300 of each cylindrical battery 1000 is also provided with an external negative electrode welding area 63 and an external positive electrode welding area 64. The external negative electrode welding area 63 is used to connect a connecting piece or a connecting circuit to the negative electrode post 320 or the housing 200 of the cylindrical battery 1000, and the external positive electrode welding area 64 is used to connect a connecting piece or a connecting circuit to the positive electrode post or the housing 200 of the cylindrical battery 1000. The external negative electrode welding area 63 is located on the periphery of the negative electrode welding area 61 and is configured to be arranged around the negative electrode welding area 61. The cross-section of the external positive electrode welding area 64 is generally annular. The external positive electrode welding area 64 is located on both sides of the positive electrode welding area 62 and is located on the periphery of the external negative electrode welding area 63 . The cross section of the external positive electrode welding area 64 is substantially an open ring.

[0129] In some embodiments of the present application, a method for preparing a battery comprising the above-mentioned laminated electrode assembly 100 is also provided, the preparation method comprising the following steps:

[0130] Prepare circular positive electrode sheet 20 and negative electrode sheet 10, as well as first separator 41 and second separator 42;

[0131] The first separator 41, the negative electrode sheet 10, the second separator 42 and the positive electrode sheet 20 are stacked in sequence, wherein the extension direction of the negative electrode tab 12 of the negative electrode sheet 10 is opposite to the extension direction of the positive electrode tab 22 of the positive electrode sheet 20;

[0132] The negative electrode tab 12 is folded along one side of the electrode assembly 100, wherein the folding direction of the negative electrode tab 12 can be folded toward the end close to the cap assembly 300, and the positive electrode tab 22 is folded along the other side of the electrode assembly, wherein the folding direction of the positive electrode tab 22 can be folded toward the end close to the cap assembly 300, thereby forming a first electrode group unit;

[0133] The same method as above is used to stack the second electrode group unit, the third electrode group unit and more electrode group units on the first electrode unit to form an electrode assembly, wherein the number of stacked electrode group units is set according to the height and capacity of the battery;

[0134] A first connector 31 is placed on one side of the electrode assembly 100, and all the negative electrode tabs 12 are welded to the first connector 31; a second connector 32 is placed on the other side of the electrode assembly 100, and all the positive electrode tabs 22 are welded to the second connector 32; wherein the first connector 31 is raised relative to the top surface of the electrode assembly 100 by a distance H1, and the second connector 32 is raised relative to the top surface of the electrode assembly 100 by a distance H2;

[0135] The portion of the first connector 31 that is higher than the top surface of the electrode assembly 100 is bent and welded to the negative electrode adapter 50, and the negative electrode adapter 50 is welded to the negative electrode column 320, and the portion of the second connector 32 that is higher than the top surface of the electrode assembly 100 is bent and welded to the cover plate 310.

[0136] An embodiment of the present application also provides a battery pack, which is used in an energy storage system, an electric vehicle, a hybrid vehicle, or an electric tool. The battery pack includes a case and a plurality of battery modules arranged inside the case, wherein each battery module includes a plurality of cylindrical batteries provided in the above embodiment.

Claims

1. A pole piece assembly (100), configured as a battery (1000), the pole piece assembly (100) comprising: A plurality of negative electrode sheets (10), each of the negative electrode sheets (10) comprising a negative electrode coating portion (11) and at least one negative electrode tab (12), at least one negative electrode tab (12) being located outside the negative electrode coating portion (11); A plurality of positive electrode sheets (20), each of the positive electrode sheets (20) comprising a positive electrode coating portion (21) and at least one positive electrode tab (22), and at least one positive electrode tab (22) being located outside the positive electrode coating portion (21); A plurality of separators (40), a plurality of the negative electrode coating parts (11), a plurality of the separators (40) and a plurality of the positive electrode coating parts (21) are stacked and arranged in an alternating manner, and a corresponding separator (40) is provided between each negative electrode coating part (11) and the corresponding positive electrode coating part (21).

2. The pole piece assembly (100) according to claim 1, wherein: The electrode assembly (100) comprises a plurality of stacked electrode group units (110), wherein the plurality of electrode group units (110) are stacked, and the stacking direction is set along the longitudinal axis direction of the electrode assembly (100). Each electrode group unit (110) comprises a first diaphragm (41), the negative electrode sheet (10), a second diaphragm (42), and the positive electrode sheet (20) which are stacked.

3. The pole piece assembly (100) according to claim 1, wherein: The diaphragm (40) includes a diaphragm substrate (43) and a solid electrolyte layer (44) provided on two opposite surfaces of the diaphragm substrate (43).

4. The pole piece assembly (100) according to claim 3, wherein: The ratio of the thickness dt of the solid electrolyte layer (44) to the thickness JT of the diaphragm substrate (43) 43 is 1 / 20 to 1 / 2.

5. The pole piece assembly (100) according to claim 1, wherein: The negative electrode coating portion (11) is set (10) as a circular coating portion, the diameter of the negative electrode coating portion (11) is set to φA, the positive electrode coating portion (21) is set to a circular coating portion, the diameter of the positive electrode coating portion (21) is set to φB, wherein φA is larger than φB.

6. The pole piece assembly (100) according to claim 5, wherein: The difference between φA and φB is not less than 0.3mm, and the difference between φA and φB is not greater than 1mm.

7. The pole piece assembly (100) according to claim 5, wherein: The diaphragm is configured as a circular diaphragm, and the diameter of the diaphragm is configured as φC, where φB≤φC≤φA.

8. The pole piece assembly (100) according to claim 5, wherein: The negative electrode tab (12) or the positive electrode tab (22) is configured as a sector-shaped piece arranged on one side of the circular coating portion, and the arc length of the sector-shaped piece is L. The calculation formula of L is 2×R×π×(α / 360°), wherein R is the radius of the circular piece, and α is the angle formed by the line connecting the two ends of the sector-shaped piece and the center of the circle where the circular piece is located, and α is set to 10°~60°.

9. The pole piece assembly (100) according to claim 1, wherein: The negative electrode tab (12) comprises a first folding section (121), wherein a folding angle β is formed between the first folding section (121) and the longitudinal axis of the electrode assembly (100), and the β is set to 3° to 10°; And / or, the positive electrode tab (22) includes a second folding section (221), a folding angle γ is formed between the second folding section (221) and the longitudinal axis of the pole piece assembly (100), and the folding angle γ is set to 3° to 10°.

10. The pole piece assembly (100) according to claim 2, wherein: The total thickness of the pole piece group unit (110) is T0, 0.2 mm ≤ T0 ≤ 1 mm.

11. The pole piece assembly (100) according to claim 8, wherein: The thickness of the separator is smaller than the thickness of the positive electrode sheet, and the thickness of the positive electrode sheet is smaller than the thickness of the negative electrode sheet.

12. The pole piece assembly (100) according to claim 2, wherein: The pole piece assembly (100) includes N pole piece group units (110), each pole piece group unit (110) includes a corresponding negative electrode tab (12) and a corresponding positive electrode tab (22), and the pole piece assembly (100) further includes a first connector (31) and a second connector (32), wherein the first connector (31) is configured to connect at least N negative electrode tabs (12), and the second connector (32) is configured to connect at least N positive electrode tabs (22), wherein N is a positive integer.

13. The pole piece assembly (100) according to claim 12, wherein: The orthographic projections of the N negative electrode tabs (12) along the longitudinal axis of the pole piece assembly (100) are located on the first connecting member (31), and the orthographic projections of the N positive electrode tabs (22) along the longitudinal axis of the pole piece assembly (100) are located on the second connecting member (32).

14. The pole piece assembly (100) according to claim 12, wherein: The thickness of the first connecting member (31) is T1, 0.08 mm ≤ T1 ≤ 0.15 mm; and / or the thickness of the second connecting member (32) is T2, 0.10 mm ≤ T2 ≤ 0.25 mm.

15. The pole piece assembly (100) according to claim 12, wherein: The N negative electrode tabs (12) and the N positive electrode tabs (22) are configured to be folded toward a first direction; Alternatively, one of the N negative electrode tabs (12) and the N positive electrode tabs (22) is configured to be folded toward the first direction, and another one of the N negative electrode tabs (12) and the N positive electrode tabs (22) is configured to be folded toward a second direction, wherein the first direction and the second direction are opposite.

16. A cylindrical battery (1000), comprising a housing (200), and a pole piece assembly (100) disposed inside the housing (200), wherein the pole piece assembly (100) comprises the pole piece assembly (100) according to any one of claims 1 to 15.

17. The cylindrical battery (1000) according to claim 16, wherein: The pole piece assembly (100) includes N pole piece group units (110), each of the pole piece group units (110) includes one negative pole tab (12) and one positive pole tab (22), and the pole piece assembly (100) further includes a first connector (31) and a second connector (32), wherein the first connector (31) is configured to connect the N negative pole tabs (12), and the second connector (32) is configured to connect the N positive pole tabs (22), and the first connector (31) and the second connector (32) are arranged at intervals.

18. The cylindrical battery (1000) according to claim 17, wherein: The cylindrical battery (1000) further includes a negative electrode adapter (50), the electrode assembly (100) includes a first negative electrode tab (122), the first negative electrode tab (122) includes a first bent section (123), the first connector (31) includes a second bent section (311), the second bent section (311), the first bent section (123) and the negative electrode adapter (50) are electrically connected in sequence and stacked on the top surface of the electrode assembly (100); and / or, The cylindrical battery (1000) further includes a positive electrode insulating member (51), the pole piece assembly (100) includes a first positive electrode tab (222), the first positive electrode tab (222) includes a third bent section (223), the second connecting member (32) includes a fourth bent section (321), and the fourth bent section (321), the third bent section (223) and the positive electrode insulating member (51) are sequentially stacked on the top surface of the pole piece assembly (100).

19. The cylindrical battery (1000) according to claim 17, wherein: The cylindrical battery (1000) further includes a positive electrode adapter (52), the electrode assembly (100) includes a first positive electrode tab (222), the first positive electrode tab (222) includes a third bent section (223), the second connector (32) includes a fourth bent section (321), the fourth bent section (321), the third bent section (223) and the positive electrode adapter (52) are electrically connected in sequence and stacked on the top surface of the electrode assembly (100); and / or, The cylindrical battery (1000) further includes a negative electrode insulating member (53), the electrode assembly (100) includes a first negative electrode tab (122), the first negative electrode tab (122) includes a first bent section (123), the first connecting member (31) includes a second bent section (311), and the second bent section (311), the first bent section (123) and the negative electrode insulating member (53) are electrically connected in sequence and stacked on the top surface of the electrode assembly (100).

20. The cylindrical battery (1000) according to claim 18 or 19, wherein: The length of the second bending section (311) is set to H1, the length of the fourth bending section (321) is set to H2, the length of the negative electrode adapter (50) is set to B1, and the radius of the electrode assembly (100) is set to R1, wherein R1 / 3≤H1≤R1 / 2, and / or R1 / 3≤H2≤R1 / 2, and / or R1≤B1≤3R1 / 2.

21. The cylindrical battery (1000) according to claim 17, wherein: The cylindrical battery further comprises a negative electrode adapter (50), the electrode assembly (100) comprises a first negative electrode tab (122), the first negative electrode tab (122) comprises a first bent section (123), the first connector (31) comprises a second bent section (311), the second bent section (311), the first bent section (123) and the negative electrode adapter (50) are sequentially electrically connected and stacked on the top surface of the electrode assembly (100); and / or, The cylindrical battery (1000) further includes a positive electrode adapter (52), the electrode assembly (100) includes a second positive electrode tab (224) located at the bottom end of the electrode assembly (100), the second positive electrode tab (224) includes a fifth bending section (225), the second connector (32) includes a sixth bending section (322), the sixth bending section (322), the fifth bending section (225) and the positive electrode adapter (52) are electrically connected in sequence and stacked on the bottom end surface of the electrode assembly (100).

22. The cylindrical battery (1000) according to claim 17, wherein: The cylindrical battery (1000) includes a positive electrode adapter (52), the electrode assembly (100) includes a first positive electrode tab (222), the first positive electrode tab (222) includes a third bent section (223), the second connector (32) includes a fourth bent section (321), the fourth bent section (321), the third bent section (223) and the positive electrode adapter (52) are electrically connected in sequence and stacked on the top surface of the electrode assembly (100); and / or, The cylindrical battery (1000) further includes a negative electrode adapter (50), the electrode assembly (100) includes a second negative electrode tab (124) located at the bottom end of the electrode assembly (100), the second negative electrode tab (124) includes a seventh bent section (125), the first connector (31) includes an eighth bent section (312), the eighth bent section (312), the seventh bent section (125) and the negative electrode adapter (50) are electrically connected in sequence and stacked on the bottom end surface of the electrode assembly (100).

23. The cylindrical battery (1000) according to claim 17, wherein: The cylindrical battery (1000) includes an insulating film (60), a portion of the insulating film (60) is disposed between the first connector (31) and the housing (200), and another portion of the insulating film (60) is disposed between the second connector (32) and the housing (200).

24. A battery module comprising a plurality of batteries, wherein the batteries are cylindrical batteries according to any one of claims 16 to 23. 25 . A battery pack comprising a box and a plurality of battery modules disposed inside the box, wherein the battery modules comprise the battery module according to claim 24 .