Pole piece assembly, cylindrical battery and battery module

Abstract

The utility model provides a pole piece assembly, a cylindrical battery and a battery module, the pole piece assembly comprises a plurality of negative pole pieces, each negative pole piece comprises a negative pole coating part and at least one negative pole lug, and at least one negative pole lug is positioned on the outer side of the negative pole coating part; each positive pole piece comprises a positive pole coating part and at least one positive pole lug, and the at least one positive pole lug is positioned on the outer side of the positive pole coating part; a plurality of diaphragms, wherein a corresponding diaphragm is arranged between each negative electrode coating part and the corresponding positive electrode coating part; wherein the plurality of negative electrode coating parts, the plurality of diaphragms and the plurality of positive electrode coating parts are mutually stacked and arranged in a staggered manner. The structure of the pole piece assembly is beneficial to reducing the internal resistance of the battery.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and in particular to a pole piece assembly, a cylindrical battery and a battery module. Background Art

[0002] 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.

[0003] 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 mostly adopt a full-ear structure to further improve their rate performance.

[0004] For cylindrical batteries with full-ear structures, the inner and outer circles 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 current collectors. The current path in the area corresponding to the inner circle of the pole piece can be referred to as follows Figure 2 The current path in the area corresponding to the outer ring of the pole piece can be referred to as Figure 2 The current path in the area where the pole ear of the pole piece is located can be referred to as follows Figure 2 Path 1 shown.

[0005] In the battery winding structure, a pole piece is wound. When the battery diameter increases, the length of the wound pole piece will also increase accordingly. Because the pole piece is wound continuously, the resistance of each part of the pole piece forms a series structure. In this series structure, the current on each pole piece passes through each part of the pole piece, and the resistance will also be superimposed.

[0006] In the battery winding structure, as the battery height increases, the path length of the current in the winding structure will also increase, which will lead to the path of the current through the winding core, such as Figure 2 As the length of the path 1 shown increases, the resistance also increases. Because the current needs to pass through the wound pole piece to complete the normal operation of the battery, the resistances that the current passes through on the pole piece will be superimposed, resulting in an increase in the internal resistance of the winding core.

[0007] As the battery diameter increases, the circumference of the outer ring of the winding structure increases, which may lead to an increase in the length of the tab part that is cut off, resulting in the following Figure 2 The increase in the length of the path 3 shown indirectly leads to an increase in the internal resistance of the battery.

[0008] Therefore, as the battery size increases, the internal resistance of the cylindrical battery will increase, which in turn affects the battery rate performance. Utility Model Content

[0009] The embodiments of the utility model provide a pole piece assembly, a cylindrical battery and a battery module, which can improve the technical problem of large internal resistance of the cylindrical battery.

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

[0011] A plurality of negative electrode sheets, each of which comprises 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 which comprises 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 negative electrode coating parts, a plurality of separators and a plurality of positive electrode coating parts are stacked and arranged alternately, and a corresponding separator is arranged between each negative electrode coating part and the corresponding positive electrode coating part.

[0014] In one embodiment, the pole piece assembly includes a plurality of stacked pole piece group units, the plurality of pole piece group units are stacked, the stacking direction is set along the longitudinal axis direction of the pole piece assembly, and each of the pole piece group units includes a stacked first diaphragm, the negative pole piece, the second diaphragm and the positive pole piece.

[0015] In one embodiment, the separator includes a separator substrate and a solid electrolyte layer disposed on two opposite surfaces of the separator substrate.

[0016] In one embodiment, the negative electrode plate is configured as a circular plate, the diameter of the negative electrode plate is configured as φA, the positive electrode plate is configured as a circular plate, the diameter of the positive electrode plate is configured as φB, wherein φA is greater than φB.

[0017] In one embodiment, 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.

[0018] In one embodiment, the negative electrode tab or the positive electrode tab is configured as a fan-shaped piece arranged on one side of the circular pole piece, the arc length of the fan-shaped piece is L, and the calculation formula of L is 2×R×π×(α / 360°), wherein R is the radius of the circular pole piece, α is the angle formed by the line connecting the two ends of the fan-shaped piece and the center of the circle where the circular pole piece is located, and α is set to 10°~60°.

[0019] In one embodiment, the negative electrode tab includes a first folding section, and a folding angle β is formed between the first folding section and the longitudinal axis of the pole piece assembly, and the β is set to 3° to 10°;

[0020] And / or, the positive electrode tab includes a second folding section, and a folding angle γ is formed between the second folding section and the longitudinal axis of the pole piece assembly, and the folding angle γ is set to 3° to 10°.

[0021] In one embodiment, the total thickness of the pole piece unit is T0, 0.2 mm ≤ T0 ≤ 1 mm.

[0022] In one embodiment, the pole piece assembly includes N pole piece group units, each of the pole piece group units includes a corresponding negative electrode tab and a corresponding positive electrode tab, and the pole piece assembly also includes a first connector and a second connector, the first connector is used to connect at least N negative electrode tabs, and the second connector is used to connect at least N positive electrode tabs, where N is a positive integer.

[0023] In one embodiment, the orthographic projections of the N negative electrode tabs along the longitudinal axis of the pole piece assembly are located on the first connecting member, and the orthographic projections of the N positive electrode tabs along the longitudinal axis of the pole piece assembly are located on the second connecting member.

[0024] In one embodiment, the thickness of the first connecting member is T1, 0.08 mm ≤ T1 ≤ 0.15 mm; and / or the thickness of the second connecting member is T2, 0.10 mm ≤ T2 ≤ 0.25 mm.

[0025] In one embodiment, the N negative electrode tabs and the N positive electrode tabs are configured to be folded toward a first direction;

[0026] Alternatively, one of the N negative electrode tabs and the N positive electrode tabs is configured to be folded toward the first direction, and another one of the N negative electrode tabs and the N positive electrode tabs is configured to be folded toward a second direction, wherein the first direction and the second direction are opposite.

[0027] In a second aspect, an embodiment of the utility model provides a cylindrical battery, the cylindrical battery comprising a shell, and a pole piece assembly disposed inside the shell, the pole piece assembly comprising the above-mentioned pole piece assembly.

[0028] In one embodiment, the pole piece assembly includes N pole piece group units, each of the pole piece group units includes one negative pole lug and one positive pole lug, the pole piece assembly also includes a first connector and a second connector, the first connector is used to connect the N negative pole lugs, the second connector is used to connect the N positive pole lugs, and the first connector and the second connector are arranged at intervals.

[0029] In one embodiment, the cylindrical battery further includes a negative electrode adapter, the electrode assembly includes a first negative electrode tab, the first negative electrode tab includes a first bending section, the first connector includes a second bending section, the second bending section, the first bending section and the negative electrode adapter are electrically connected in sequence and stacked on the top surface of the electrode assembly; and / or,

[0030] The cylindrical battery also includes a positive electrode insulating member, the pole piece assembly includes a first positive electrode tab, the first positive electrode tab includes a third bending section, the second connecting member includes a fourth bending section, the fourth bending section, the third bending section and the positive electrode insulating member are sequentially stacked on the top surface of the pole piece assembly.

[0031] In one embodiment, the cylindrical battery further includes a positive electrode adapter, the electrode assembly includes a first positive electrode tab, the first positive electrode tab includes a third bending section, the second connector includes a fourth bending section, the fourth bending section, the third bending section and the positive electrode adapter are electrically connected in sequence and stacked on the top surface of the electrode assembly; and / or,

[0032] The cylindrical battery also includes a negative electrode insulating member, the pole piece assembly includes a first negative electrode tab, the first negative electrode tab includes a first bending section, the first connecting member includes a second bending section, the second bending section, the first bending section and the negative electrode insulating member are electrically connected in sequence and stacked on the top surface of the pole piece assembly.

[0033] In one embodiment, the length of the second bending section is set to H1, the length of the fourth bending section is set to H2, the length of the negative electrode adapter plate is set to B1, and the radius of the electrode assembly is set to R1, wherein R1 / 3≤H1≤R1 / 2, and / or R1 / 3≤H2≤R1 / 2, and / or R1≤B1≤3R1 / 2.

[0034] In one embodiment, the cylindrical battery further includes a negative electrode adapter, the electrode assembly includes a first negative electrode tab, the first negative electrode tab includes a first bending section, the first connector includes a second bending section, the second bending section, the first bending section and the negative electrode adapter are electrically connected in sequence and stacked on the top surface of the electrode assembly; and / or,

[0035] The cylindrical battery also includes a positive electrode adapter plate, the electrode assembly includes a second positive electrode ear located at the bottom end of the electrode assembly, the second positive electrode ear includes a fifth bending section, the second connecting member includes a sixth bending section, the sixth bending section, the fifth bending section and the positive electrode adapter plate are electrically connected in sequence and stacked on the bottom end surface of the electrode assembly.

[0036] In one embodiment, the cylindrical battery includes a positive electrode adapter, the electrode assembly includes a first positive electrode ear, the first positive electrode ear includes a third bending section, the second connector includes a fourth bending section, the fourth bending section, the third bending section and the positive electrode adapter are electrically connected in sequence and stacked on the top surface of the electrode assembly; and / or,

[0037] The cylindrical battery also includes a negative electrode adapter plate, the electrode assembly includes a second negative electrode tab located at the bottom end of the electrode assembly, the second negative electrode tab includes a seventh bending segment, the first connecting member includes an eighth bending segment, the eighth bending segment, the seventh bending segment and the negative electrode adapter plate are electrically connected in sequence and stacked on the bottom end surface of the electrode assembly.

[0038] In one embodiment, the cylindrical battery includes an insulating film, a portion of the insulating film is disposed between the first connector and the housing, and another portion of the insulating film is disposed between the second connector and the housing.

[0039] In a third aspect, an embodiment of the utility model provides a battery module, wherein the battery module includes a plurality of batteries, and the batteries are configured as the above-mentioned cylindrical batteries.

[0040] Beneficial effects of the embodiments of the utility model:

[0041] In an embodiment of the utility model, the pole piece assembly inside the cylindrical battery is arranged to include a plurality of negative pole pieces, a plurality of diaphragms and a plurality of positive pole pieces which are stacked and staggered, each negative pole piece includes a negative electrode coating portion and a negative electrode ear located outside the negative electrode coating portion, and each positive electrode piece includes a positive electrode coating portion and a positive electrode ear 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 pole piece of the stacked pole piece assembly is provided with a pole ear, which is arranged on the outside of the pole piece. Therefore, the current path of each pole piece basically extends along the radial direction of the pole piece, thereby greatly reducing the internal resistance of the pole piece assembly inside the cylindrical battery, thereby improving the rate performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 It is a schematic diagram of the structure of a battery provided by an embodiment of the utility model;

[0044] Figure 2 is a schematic diagram of the current path of a pole piece assembly in the related art;

[0045] Figure 3 It is a schematic diagram of the structure of a pole piece assembly provided in an embodiment of the utility model;

[0046] Figure 4 It is a schematic diagram of the structure of the negative electrode sheet provided by an embodiment of the utility model;

[0047] Figure 5 It is a schematic structural diagram of a positive electrode sheet provided in an embodiment of the utility model;

[0048] Figure 6 It is a schematic diagram of the structure of the diaphragm provided in the embodiment of the utility model;

[0049] Figure 7 It is a schematic cross-sectional structure diagram of a pole piece assembly unit provided in an embodiment of the utility model;

[0050] Figure 8 is a stereogram of a single-layer diaphragm provided in an embodiment of the utility model;

[0051] Fig. 9 yes Figure 8 A partial enlarged view of

[0052] Fig.10 It is a schematic diagram of the top view of the pole piece group unit provided in an embodiment of the utility model;

[0053] Fig.11 It is a schematic diagram of the stacked structure of the pole piece assembly provided in an embodiment of the utility model;

[0054] Fig.12 It is a schematic diagram of the pole ear connection structure of the pole piece assembly provided in an embodiment of the utility model;

[0055] Fig.13 It is a top view schematic diagram of the pole ear connection structure of the pole piece assembly provided by an embodiment of the utility model;

[0056] Fig.14It is a schematic diagram of the electrical connection structure of the output end of the pole piece assembly provided in an embodiment of the utility model;

[0057] Fig.15 It is a top view schematic diagram of the output end electrical connection structure of the pole piece assembly provided in an embodiment of the utility model;

[0058] Fig.16 It is a cross-sectional schematic diagram of an insulating film wrapped around a pole piece assembly provided in an embodiment of the utility model;

[0059] Fig.17 It is a top view schematic diagram of an insulating film wrapped around a pole piece assembly provided by an embodiment of the utility model;

[0060] Fig.18 It is a schematic cross-sectional structure diagram of a battery provided in the first embodiment of the utility model;

[0061] Fig.19 is a schematic diagram of a welding area of ​​a battery provided by the first embodiment of the utility model;

[0062] Fig. 20 is a schematic diagram of the cross-sectional structure of a battery provided in the second embodiment of the present utility model;

[0063] Fig.21 is a schematic cross-sectional structure diagram of a battery provided in a third embodiment of the utility model;

[0064] Fig. 22 is a schematic cross-sectional structure diagram of a battery provided in a fourth embodiment of the utility model;

[0065] Figure Number:

[0066] 1000, battery; 200, housing; 210, first side; 220, second side;

[0067] 100, pole piece assembly; 110, pole piece assembly unit;

[0068] 10. Negative electrode sheet; 11. Negative electrode coating portion; 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;

[0069] 20, positive electrode sheet; 21, positive electrode coating portion; 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;

[0070] 31, first connecting member; 311, second bending section; 312, eighth bending section; 32, second connecting member; 321, fourth bending section; 322, sixth bending section;

[0071] 40. diaphragm; 41. first diaphragm; 42. second diaphragm; 43. diaphragm substrate; 431. fiber skeleton; 44. solid electrolyte layer;

[0072] 50. Negative electrode adapter; 51. Positive electrode insulator; 52. Positive electrode adapter; 53. Negative electrode insulator;

[0073] 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;

[0074] 300, cap assembly; 310, cover plate; 320, first negative pole; 330, first pole insulator; 340, first positive pole;

[0075] 400, bottom cover assembly; 410, bottom cover; 420, second positive pole; 430, second pole insulator; 440, second negative pole; DETAILED DESCRIPTION

[0076] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the utility model, and are not used to limit the utility model. In the utility model, unless otherwise stated, the directional words used, such as "upper" and "lower", generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inside" and "outside" refer to the outline of the device.

[0077] An embodiment of the present invention provides a cylindrical battery 1000, such as Figure 1 As shown, 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 disposed inside the shell 200, and the cap assembly 300 is used to seal the open end of the shell 200.

[0078] The models of cylindrical batteries can be set to 18650, 21700, 33145, 40135, 42300, 4680 and 46135, etc. The relevant parameters of the cylindrical batteries of the above models can be referred to as shown in the following Table 1:

[0079] Table 1. Cylindrical battery model parameter table

[0080] Battery model 18650 21700 33145 40135 42300 4680 46135 Diameter D of the pole piece assembly 17.4 20.5 32.4 39.5 41.4 44.6 44.6 Pole piece width W 63 68 140 130 295 76 131 W / D 3.6 3.3 4.3 3.2 7.1 1.7 2.9

[0081] 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.

[0082] 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 mostly adopt a full-ear structure to further improve their rate performance.

[0083] For cylindrical batteries with full-ear structures, the inner and outer circles 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 current collectors. The current path in the area corresponding to the inner circle of the pole piece can be referred to as follows Figure 2 The current path I2 shown in the figure can be referred to as Figure 2 The path I3 shown in the figure can be referred to as the current path in the area where the pole ear of the pole piece is located. Figure 2 Path I1 is shown.

[0084] The battery core assembly adopts a pole piece winding method. When the diameter of the battery 1000 increases, the length of the wound pole piece will also increase accordingly. Because the pole piece is wound continuously, the resistance of each part of the pole piece forms a series structure. In this series structure, the current on each pole piece passes through each part of the pole piece, and the resistance will also be superimposed.

[0085] Therefore, as the height of the battery increases, the path length of the current in the winding core assembly will also increase, resulting in the path of the current through the winding core, e.g. Figure 2 As the length of the path 1 shown increases, the resistance also increases. Because the current needs to pass through the wound pole piece to complete the normal operation of the battery, the resistances that the current passes through on the pole piece will be superimposed, resulting in an increase in the internal resistance of the winding core.

[0086] As the battery diameter increases, the circumference of the avoidance layer of the lower outer ring of the core assembly increases, which may lead to an increase in the length of the tab portion that is cut off, resulting in the following Figure 2 The increase in the length of the path 3 shown indirectly leads to an increase in the internal resistance of the battery.

[0087] Therefore, as the battery size increases, the internal resistance of the cylindrical battery will increase, which in turn affects the battery rate performance.

[0088] In view of the problem that the internal resistance of the pole piece assembly 100 in the large-sized cylindrical battery in the related art is relatively large, a new structure of the pole piece assembly 100 is provided in the embodiment of the utility model, such as Figures 3 to 6 As shown, the electrode assembly 100 includes a plurality of negative electrode sheets 10, a plurality of separators 40 and a plurality of positive electrode sheets 20, wherein a separator 40 is arranged between each of the negative electrode sheets 10 and each of the positive electrode sheets 20, wherein the plurality of negative electrode sheets 10, the plurality of separators 40 and the plurality of 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, at least one of the negative electrode tabs 12 is arranged outside 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, at least one of the positive electrode tabs 22 is arranged outside the positive electrode coating portion 21.

[0089] Among them, the number of negative electrode tabs 12 set on each negative electrode plate 10 can be one, two, three or more; the number of positive electrode tabs 22 set on each positive electrode plate 20 can be one, two, three or more. In a preferred implementation, one negative electrode tab 12 is set on each negative electrode plate 10, and one positive electrode tab 22 is set on each positive electrode plate 20.

[0090] Compared with the related art in which the electrode sheet assembly is wound along the central axis of the cylindrical battery, the current path of the winding core assembly formed by the winding will increase with the increase in the size of the battery. In the embodiment of the utility model, the multiple negative electrode sheets 10, multiple separators 40 and multiple positive electrode sheets 20 of the electrode sheet assembly 100 are stacked and arranged, each negative electrode sheet 10 is provided with at least one negative electrode ear 12, and each positive electrode sheet 20 is provided with at least one positive electrode ear 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 utility model is significantly reduced, and then the internal resistance of each electrode sheet is significantly reduced, so that the internal resistance of the electrode sheet assembly 100 is significantly reduced, which is beneficial to improve the rate performance of the battery 1000.

[0091] Furthermore, by stacking the pole pieces of the pole piece assembly 100 along the longitudinal axis direction 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 use of the internal space of the battery housing 200, thereby facilitating the increase of the volume of the battery 1000. Figure 3The Y direction is shown, wherein, in a cylindrical battery, the longitudinal axis direction of the pole piece assembly 100 is consistent with the height direction of the battery.

[0092] like Figure 7 As shown, the electrode assembly 100 includes a plurality of stacked electrode assembly units 110, and the plurality of electrode assembly units 110 are stacked along the longitudinal axis direction of the electrode assembly 100. Each electrode assembly unit 110 includes a first diaphragm 41, a negative electrode sheet 10, a second diaphragm 42, and a positive electrode sheet 20 stacked in sequence. A complete electrode assembly unit 110 is formed by using a layer of diaphragm 40, a layer of negative electrode sheet 10, a layer of positive electrode sheet 20, and a layer of diaphragm 40, and a stacking design is performed according to the height of the battery 1000 and the total thickness T0 of the electrode assembly unit 110, and there is no center hole design, so that the internal space of the cylindrical battery 1000 can be more effectively utilized.

[0093] The negative electrode sheet 10 includes a negative electrode substrate, a portion of the negative electrode substrate is coated with a negative electrode active material on its outer surface to form a negative electrode coating portion 11 , and a portion of the negative electrode substrate is not coated with a negative electrode active material on its outer surface to form a negative electrode tab 12 .

[0094] The negative electrode substrate refers to a thin sheet-like substrate used to accommodate the negative electrode active material in the battery 1000, and its function is to provide support and conductivity. Suitable negative electrode substrates include copper foil, aluminum foil, stainless steel mesh, titanium foil, etc.

[0095] Negative electrode active materials generally 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. Suitable alloy materials include lithium alloys, such as lithium aluminum, lithium silicon, etc.

[0096] 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 .

[0097] 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.

[0098] 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.

[0099] The material of the diaphragm 40 is generally made of polymer or ceramic material. Suitable polymer materials include polychromic acrylate (PVdF), polyvinyl alcohol (PVA), polyvinyl glucose (PEG), and suitable ceramic materials include alumina (Al2O3) and lithium phosphate (Li3PO4).

[0100] like Figure 8 and Fig. 9 As shown, the battery 1000 is configured as a solid electrolyte battery, and the battery 1000 can be activated, formed and divided into different volumes only 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 an ion conductive material, such as ceramics, polymers or composite materials, and has high ion conductivity. Since the solid electrolyte does not contain an organic solvent, 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.

[0101] The thickness JT of the above-mentioned diaphragm substrate 43 is set to 6um to 20um, 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 implementation, the thickness JT of the diaphragm substrate 43 can be set to 8um, 10um, 12um, 14um, 16um, 18um, and a value between any two of the above values ​​or a range between any two of the above values, and 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, and 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 be greater than 20um, it is not conducive to the overall lightweight design of the pole piece assembly 100. When the thickness JT of the diaphragm substrate 43 is set to be less than 6um, the overall mechanical strength of the diaphragm 40 is insufficient, thereby affecting the stability and service life of the diaphragm 40.

[0102] refer to Figure 4 , Figure 5 as well as Fig.10As shown, the negative electrode sheet 10 is set as a circular sheet, and the diameter of the negative electrode sheet 10 is set to φA, and the positive electrode sheet 20 is set as a circular sheet, and the diameter of the positive electrode sheet 20 is set to φB, wherein φA is greater than φB. Taking the lithium-ion battery 1000 as an example, the lithium-ion battery 1000 has the problem of lithium precipitation, and the diameter of the negative electrode sheet 10 is set to be greater than the diameter of the positive electrode sheet 20. The part of the negative electrode sheet 10 outside the positive electrode sheet 20 is used to prevent lithium branch crystals from precipitating and then piercing the diaphragm 40.

[0103] In a preferred embodiment, the diameter φA of the negative electrode sheet 10 exceeds the diameter φB of the positive electrode sheet 20 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, and a value or range between any two of the above values.

[0104] Considering that keeping the negative electrode plate 10 and the positive electrode plate 20 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 stacking equipment, and there is a certain positioning deviation in 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 configured as a solid electrolyte lithium-ion battery, the channel range of 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.

[0105] like Figure 6 As shown, the separator 40 is set as a circular separator 40, and the diameter of the separator 40 is set to 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, so that the separator 40 is conducive to completely covering the negative electrode coating portion 11 of the negative electrode plate 10.

[0106] Further references Figure 4 , Figure 5 as well as Fig.10As shown, the negative electrode tab 12 or the positive electrode tab 22 is configured as a fan-shaped piece arranged on one side of the circular coating portion, and the arc length of the fan-shaped piece is L, and the calculation formula of L is R×π×(α / 180°), where R is the radius of the circular pole piece, α is the angle formed by the line connecting the two ends of the fan-shaped piece and the center of the circular pole piece, and 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 pole piece, it is beneficial to fold the positive electrode tab 22 and the negative electrode tab 12. In some specific embodiments, α is set to 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, and a value between any two of the above values ​​or a range between any two of the above values.

[0107] The area of ​​the circular pole piece is 2×π×R 2 , the arc length L of the pole ear is R×π×(α / 180°). After research, the utility model inventor found that when α is set to 10°~60°, it is beneficial to balance the bending effect of the pole ear, the current collecting area of ​​the effective current of the pole ear, 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 pole ear is less than R×π×(1 / 18), and the corresponding current collecting capacity of the pole ear 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 pole ear is greater than R×π×(1 / 3), and the width corresponding to the arc length of the pole ear is wider. The pole ear is prone to rupture when bending, which in turn affects the pole current capacity of the pole ear and is difficult to meet the subsequent welding requirements of the pole ear.

[0108] Among them, the angle formed by the line connecting the two ends of the fan-shaped piece where the negative electrode tab 12 is located and the center of the negative circular electrode piece is α1, and the angle formed by the line connecting the two ends of the fan-shaped piece where the positive electrode tab 22 is located and the center of the positive circular electrode piece is α2. In some embodiments, α1 and α2 are set to the same, and in some optional embodiments, α1 and α2 are set to different.

[0109] like Fig.10 As shown, the projection surface of the negative electrode tab 12 on the radial cross section of the pole piece assembly 100 is located on one side of the central axis of the circular pole piece, and the projection surface of the positive electrode tab 22 on the radial cross section of the pole piece assembly 100 is located on the other side of the central axis of the circular pole piece, and the projection surface of the negative electrode tab 12 on the radial cross section of the pole piece assembly 100 and the projection surface of the positive electrode tab 22 on the radial cross section of the pole piece assembly 100 are symmetrically arranged about the center of the circular pole piece. In other optional embodiments, the projection surface of the negative electrode tab 12 on the radial cross section of the pole piece assembly 100 and the projection surface of the positive electrode tab 22 on the radial cross section of the pole piece assembly 100 are asymmetrically arranged about the center of the circular pole piece.

[0110] Further references Figure 7 As shown, the negative electrode tab 12 includes a first folding section 121, which is configured to be formed by folding the negative electrode tab 12, and a folding angle β is formed between the first folding section 121 and the longitudinal axis of the pole piece assembly 100, and β is set to 3° to 10°. When the folding angle β of the negative electrode tab 12 is within the above range, it is beneficial to stack and connect multiple negative electrode tabs 12 in parallel. In a specific implementation, β can be 4°, 5°, 6°, 7°, 8°, 9°, and a value or range between any two of the above values.

[0111] The positive electrode tab 22 includes a second folding section 221, which is configured to be formed by folding the positive electrode tab 22, and a folding angle γ is formed between the positive electrode tab 22 and the longitudinal axis of the pole piece assembly 100, and the 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 beneficial to stack and connect multiple positive electrode tabs 22 in parallel. In a specific implementation, γ can be 4°, 5°, 6°, 7°, 8°, 9°, and a value or range between any two of the above values.

[0112] After research, the inventor found that taking into account the convenience of stacking multiple electrode group units 110 and the easy shaping of the electrode ears after stacking, and 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°.

[0113] 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.

[0114] Further references Figure 7As shown, 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 in the above range, it is beneficial to set up a plurality of 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 according to 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.

[0115] The inventor has found through research that when the battery 1000 is set as a solid-state lithium-ion battery, the positive electrode sheet 20 of the lithium-ion battery provides lithium ions, and the negative electrode sheet 10 provides a conductive carbon layer structure. In order to ensure that the lithium ions are fully received and embedded in the carbon layer structure of the negative electrode sheet 10 during the charge and discharge process, the loading capacity of the negative electrode sheet 10 is greater than the inherent number of lithium ions of the positive electrode sheet 20. At the same time, 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 the thickness of the positive electrode sheet 20.

[0116] Furthermore, by studying the total thickness T0 of different electrode assembly units 110 , it is found that when the total thickness T0 of the electrode assembly unit 110 is set to 0.20 mm to 0.5 mm, it is beneficial to maintain the discharge rate capability of the battery 1000 .

[0117] Table 1 Comparison table of thickness of each layer of the electrode unit and battery discharge rate performance

[0118]

[0119] From the data in Table 1, it can be found that the thickness of the positive electrode sheet 20 in the electrode sheet unit 110 is 0.08 mm to 0.20 mm, the thickness of the negative electrode sheet 10 is 0.1 mm to 0.3 mm, 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 .

[0120] like Fig.11As shown, the negative electrode tab 12 includes a first folded segment 121, and the length of the first folded segment 121 is L1, 2T0≤L1≤10T0. It can be understood that the ratio of the length L1 of the first folded segment 121 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 L1 of the first folded segment 121 to the thickness T0 of the electrode assembly 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.

[0121] The positive electrode tab 22 includes a second folded section 221, the length of the second folded section 221 is L2, 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, and a value or range between any two of the above values.

[0122] When the folding angle β of the first folding segment 121 of the 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 the multiple negative electrode tabs 12 can be conveniently shaped and welded. When the folding angle γ of the second folding segment 221 of the 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 the multiple positive electrode tabs 22 can be conveniently shaped and welded.

[0123] refer to Figures 12 to 15 As shown, in some embodiments provided by the present utility model, the pole piece assembly 100 includes N pole piece group units 110, the N pole piece group units 110 include N negative electrode tabs 12 and N positive electrode tabs 22, the pole piece assembly 100 also includes a first connector 31 and a second connector 32, the first connector 31 is used to connect at least N negative electrode tabs 12, 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.

[0124] 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 pole piece assembly units 110 are connected in parallel through the first connector 31 and the second connector 32, which is conducive to further reducing the internal resistance of the pole piece assembly 100.

[0125] 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 direction of the electrode assembly 100 are located on the first connecting member 31, so that the N negative electrode tabs 12 can all 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 direction of the electrode assembly 100 are located on the second connecting member 32, so that the N positive electrode tabs 22 can all be connected to the second connecting member 32.

[0126] Further references Fig.13 As shown, 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.

[0127] In a specific embodiment, the thickness T1 of the first connecting member 31 can be 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, a value between any two of the above values, or a range between any two of the above values, and the thickness T2 of the second connecting member 32 can be 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.23mm, a value between any two of the above values, or a range between any two of the above values.

[0128] The main 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 channel. The thickness T1 of the first connector 31 satisfies 0.08mm≤T1≤0.15mm. The inventor has found through research that when the thickness T1 of the first connector 31 is less than 0.08mm, the current capacity of the battery 1000 is insufficient and cannot meet the discharge rate requirement of the battery above 6C. Multiple negative electrode tabs are welded to the first connector 31. During welding, a high-energy electric arc or laser is generally used to instantaneously heat the tab and the first connector 31 to form a welding point between the tab 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, thereby causing the current collecting capacity of the battery 1000 to decrease, thereby failing to meet the 6C overcurrent capacity requirement.

[0129] The thickness T2 of the second connector 32 satisfies 0.10mm≤T2≤0.25mm. As above, when the thickness T2 of the second connector 32 is less than 0.10mm, the current carrying capacity of the battery 1000 is insufficient and cannot meet the discharge rate requirement of the battery above 6C. Multiple positive pole tabs are welded on the second connector 32. When the thickness T2 of the second connector 32 is greater than 0.25mm, the increase in the thickness of the second connector 32 will cause the heat transfer speed to slow down, and the welding heat 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, it will cause the tab to melt through, thereby causing the current collecting capacity of the battery 1000 to decrease, and thus failing to meet the current carrying capacity requirement of 6C.

[0130] 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 projection distance of the negative electrode tab 12 on the radial section of the pole piece assembly 100, and the thickness t2 of the positive electrode tab 22 is set to the projection distance of the positive electrode tab 22 on the radial section of the pole piece assembly 100. The thickness t1 of the negative electrode tab 12 can be 0.02mm, 0.05mm, 0.08mm, 0.1mm, 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 positive electrode tab 22 can be 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, and a value between any two of the above values ​​or a range between any two of the above values.

[0131] The material of the first connector 31 and the material of the second connector 32 may be different materials depending on the type of the applicable battery 1000. For example, when the cylindrical battery 1000 is configured as 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 configured as 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.

[0132] The first connector 31 is configured to cover all the negative electrode tabs 12. The negative electrode tabs 12 are arranged as fan-shaped sheet structures. Correspondingly, the first connector 31 is arranged as an arc-shaped structure. The circumference of the first connector 31 is greater than the circumference of the negative electrode tabs 12. Specifically, the circumference of the arc where the first connector 31 is located exceeds the circumference of the fan where the negative electrode tabs 12 are located by 0.5mm to 1mm, so that the first connector 31 can surround the negative electrode tabs 12. Among them, the circumference of the arc where the first connector 31 is located exceeds the circumference of the fan where the negative electrode tabs 12 are located by 0.5mm to 1mm, which is conducive to the electrical connection of multiple negative electrode tabs 12 with the first connector 31 through laser welding, and the first connector 31 can cover the negative electrode tabs 12.

[0133] Correspondingly, the second connector 32 is configured to cover all the positive pole tabs 22, the positive pole tabs 22 are arranged as a fan-shaped sheet structure, the second connector 32 is arranged as an arc-shaped structure, and the circumference of the second connector 32 is greater than the circumference of the positive pole 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 pole tab 22 is located by 0.5mm to 1mm, so that the second connector 32 can surround the positive pole 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 pole tab 22 is located by 0.5mm to 1mm, which is conducive to the electrical connection of multiple positive pole tabs 22 with the second connector 32 by laser welding, and the second connector 32 can cover the positive pole tab 22.

[0134] Further references Fig.12As shown, the N negative electrode tabs 12 and the N positive electrode tabs 22 are configured to be folded toward a first direction; or, 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 the other 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 second direction and the first direction are set to opposite directions. In a specific implementation, the first direction can be set to a direction toward the cap assembly 300 close to the cylindrical battery 1000, and correspondingly, the second direction is set to a direction away from the cap assembly 300. Alternatively, the first direction can also be set to a direction away from the cap assembly 300, and correspondingly, the second direction is set to a direction toward the cap assembly 300.

[0135] 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 order, and all the positive electrode tabs 22 are connected to the second connector 32 in order.

[0136] like Figures 14 to 22 As shown, the pole piece assembly 100 includes N pole piece group units 110, each of the pole piece group units 110 includes a negative pole lug 12 and a positive pole lug 22, and the pole piece assembly 100 also includes a first connector 31 and a second connector 32, the first connector 31 is used to connect the N negative pole lugs 12, and the second connector 32 is used to connect the N positive pole lugs 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.

[0137] In a preferred embodiment, the housing 200 of the cylindrical battery 1000 includes a first side 210 and a second side 220 that are arranged opposite to each other, the first connector 31 is arranged close to the first side 210, and the second connector 32 is arranged close to the second side 220. By respectively arranging the first connector 31 and the second connector 32 on both sides of the cylindrical battery 1000, it is convenient to fold a plurality of negative electrode tabs 12 in one direction and weld them to the first connector 31, and fold a plurality of positive electrode tabs 22 in one direction and weld them to the second connector 32, thereby forming a unified current collecting channel on both sides of the cylindrical battery 1000, and improving the efficiency of tab shaping and welding.

[0138] The battery 1000 further includes a cap assembly 300, which includes a cap plate 310, an electrode column and an electrode column insulator, and an electrical connection structure is provided between the electrode assembly 100 and the electrode column. Fig.18As shown, a first negative pole 320 is provided on the cap assembly 300, a first pole insulator 330 is provided between the first negative pole 320 and the cover plate 310, and the first negative pole 320 is further electrically connected to the negative output end of the pole piece assembly 100 through a negative electrode adapter 50, wherein the negative electrode adapter 50 is provided between the first negative pole 320 and the first connector 31, and the negative electrode adapter 50 is not only used to transfer current, but also used to improve the current collecting 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.

[0139] The shell 200 is electrically connected to the positive output terminal of the pole piece assembly 100, and a positive insulator 51 and the above-mentioned negative pole adapter plate 50 are also provided on the top surface of the pole piece assembly 100, wherein the positive insulator 51 is arranged close to the negative pole adapter plate 50, the positive insulator 51 is in contact with the negative pole adapter plate 50 or a gap is provided between the positive insulator 51 and the negative pole adapter plate 50, and the positive insulator 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.

[0140] In other alternative embodiments, Fig. 20 As shown, a first positive pole column 340 is arranged on the cap assembly 300, and the first positive pole column 340 is further electrically connected to the positive output terminal of the pole piece assembly 100 through the positive adapter plate 52, and the shell 200 is electrically connected to the negative output terminal of the pole piece assembly 100, and a negative insulator 53 and the above-mentioned positive adapter plate 52 are arranged on the top surface of the pole piece assembly 100, wherein the negative insulator 53 is arranged close to the positive adapter plate 52, and the negative insulator 53 is in contact with the positive adapter plate 52 or a gap is arranged between the negative insulator 53 and the positive adapter plate 52, and the negative insulator 53 is used to prevent a short circuit connection between the positive output terminal and the negative output terminal of the pole piece assembly 100.

[0141] Continue to refer Figures 15 to 20 As shown, the pole piece assembly 100 includes a first negative pole ear 122 and a first positive pole ear 222 arranged near the cap assembly 300, wherein the first negative pole ear 122 includes a first bending section 123, 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 pole piece 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.

[0142] The first positive electrode ear 222 includes a third bending segment 223, and the second connecting member 32 includes a fourth bending segment 321. The fourth bending segment 321, the third bending segment 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 segment 223 is not greater than the length of the fourth bending segment 321, and the length H2 of the fourth bending segment 321 is less than the length A2 of the positive electrode insulating member 51.

[0143] Among them, the negative electrode adapter plate 50 and the second bending section 311 of the first connecting member 31 are welded to achieve electrical connection, and the welding area between the negative electrode adapter plate 50 and the first connecting member 31 is mainly affected by the length B1 of the negative electrode adapter plate 50 and the length H1 of the second bending section 311, and the welding area between the negative electrode adapter plate 50 and the first connecting member 31 further determines the current capacity of the battery 1000.

[0144] Furthermore, the fourth bending section 321 of the second connecting member 32 is welded to the cover plate 310 to achieve electrical connection, and the welding area between the cover plate 310 and the second connecting member 32 is mainly affected by the length H2 of the fourth bending section 321 of the second connecting member 32, and the welding area between the second connecting member 32 and the cover plate 310 further determines the current capacity of the battery 1000.

[0145] The inventor has found through research that when H1 satisfies: R1 / 3≤H1≤R1 / 2, H2 satisfies: R1 / 3≤H2≤R1 / 2, and B1 satisfies: R1≤B1≤3R1 / 2, it is beneficial to reduce the internal resistance of the battery 1000, thereby improving the overcurrent capacity of the battery 1000. Specific experimental data can be referred to as shown in Table 3 below.

[0146] Table 3 Performance influence of H1, H2, and B1 on the internal resistance of the battery

[0147]

[0148] 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 when the charge and discharge state is 30% of the power. 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 measured to be greater than 1mΩ when the charge and discharge state is 30% of the power. 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, and it cannot be implemented.

[0149] Further, the lengths of the first bending section 123 and the second bending section 311 are substantially the same, so that the first connector 31 can completely cover the first negative electrode tab 122, and the first bending section 123 and the second bending section 311 are both arranged perpendicular to the longitudinal axis of the battery 1000. The lengths of the third bending section 223 and the fourth bending section 321 are substantially the same, so that the second connector 32 can completely cover the first positive electrode tab 222, and the third bending section 223 and the fourth bending section 321 are both arranged perpendicular to the longitudinal axis of the battery 1000.

[0150] In other optional embodiments, the cap assembly 300 may also be provided with a first negative electrode column 320 and a first positive electrode column 340, and the first positive electrode column 340 is electrically connected to the second connector 32 via a positive electrode adapter 52. The first negative electrode column 320 is preferably a copper-aluminum composite column, and the first positive electrode column 340 is preferably an aluminum column.

[0151] In another embodiment provided in the present application, Fig.21 As shown, 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 column 320 is provided on the cap assembly 300, a second positive electrode column 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 column 320 provided on the cap assembly 300, the bottom cover assembly 400 includes a bottom cover 410, a second positive electrode column 420 and a second electrode column insulating member 430 provided between the bottom cover 410 and the second positive electrode column 420, the positive output end of the pole piece assembly 100 is electrically connected to the second positive electrode column 420, wherein the electrical connection method between the negative output end of the pole piece assembly 100 and the negative electrode column 320 is the same as The same as 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.

[0152] In another embodiment provided in the present application, Fig. 22As shown, a first positive pole 340 is arranged on the cap assembly 300, a second negative pole 440 is arranged on the bottom cover assembly 400, the positive output end of the pole piece assembly 100 is electrically connected to the first positive pole 340 arranged on the cap assembly 300, a positive electrode adapter 52 is arranged on the top surface of the pole piece assembly 100, the first positive pole ear 222 includes a third bending section 223, 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 pole piece assembly 100; and / or,

[0153] A negative electrode adapter plate 50 is arranged on the bottom end surface of the pole piece assembly 100, and the pole piece assembly 100 includes a second negative electrode ear 124 located at the bottom end of the pole piece assembly 100, and the second negative electrode ear 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 pole piece assembly 100.

[0154] 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 and 3R1 / 2, which is beneficial to improving the current collection capacity of the battery 1000.

[0155] Further references Fig.16 and Fig.17 As shown, the battery 1000 further includes an insulating film 60, which is used to insulate the periphery of the pole piece assembly. The insulating film 60 includes at least two parts, one part of the insulating film 60 is disposed between the first connecting member 31 and the housing 200, and the other part of the insulating film 60 is disposed between the second connecting member 32 and the housing 200. Fig.17 As shown, in a preferred embodiment, the insulating film 60 is arranged to cover the entire periphery of the pole piece assembly.

[0156] 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.

[0157] Further references Fig.19As shown, the negative electrode welding area 61 of the cylindrical battery 1000 is located in the central area of ​​the cylindrical battery 1000, wherein the negative electrode welding area 61 is configured to electrically connect the negative electrode plate 10, the first connector 31 and the negative electrode adapter 50 in sequence, and the positive electrode welding area 62 of the cylindrical battery 1000 is disposed close to one side of the cylindrical battery 1000, and the positive electrode welding area 62 is configured to electrically connect the positive electrode plate 20 and the second connector 32 in sequence. The cross section of the negative electrode welding area 61 is roughly circular, and the positive electrode welding area 62 is roughly fan-shaped.

[0158] The above-mentioned negative electrode adapter 50 is mainly used to realize the external electrical connection of the battery 1000. The thickness of the negative electrode adapter 50 is set to be between 0.8 and 1.2 times the thickness of the external welding layer, and the thickness of the external welding layer is set to 0.6 mm to 1.0 mm. The thickness of the positive electrode insulating member 51 mainly meets the assembly requirements, so that the electrical connection area between the pole ear of the pole piece assembly 100 and the external output end of the battery can be welded and positioned. The thickness of the positive electrode insulating member 51 can be set to 0.8 mm to 1.5 mm as needed.

[0159] The battery module includes a plurality of cylindrical batteries 1000, which are arranged in series, parallel or mixed connection to meet the capacity requirements of the battery module. An external negative electrode welding area 63 and an external positive electrode welding area 64 are also arranged on the cap assembly 300 of each cylindrical battery 1000, the external negative electrode welding area 63 is used for connecting the connecting piece or the connecting circuit to the negative electrode pole 320 or the shell 200 of the cylindrical battery 1000, and the external positive electrode welding area 64 is used for connecting the connecting piece or the connecting circuit to the positive electrode pole or the shell 200 of the cylindrical battery 1000, wherein the external negative electrode welding area 63 is located at the periphery of the negative electrode welding area 61, and the external negative electrode welding area 63 is configured to be arranged around the negative electrode welding area 61, and the cross section of the external positive electrode welding area 64 is roughly annular. The external positive electrode welding area 64 is located on both sides of the positive electrode welding area 62 and the external positive electrode welding area 64 is located on the outer 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.

[0160] In some embodiments of the present invention, a method for preparing a battery including the above-mentioned laminated pole piece assembly 100 is also provided, and the preparation method comprises the following steps:

[0161] Prepare a circular positive electrode sheet 20 and a negative electrode sheet 10, as well as a first separator 41 and a second separator 42;

[0162] 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;

[0163] 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;

[0164] The second electrode group unit, the third electrode group unit and more electrode group units are stacked on the first electrode unit in the same manner as above to form an electrode assembly, wherein the number of stacked electrode group units is set according to the height and capacity of the battery;

[0165] A first connector 31 is placed on one side of the pole piece assembly 100, and all the negative pole tabs 12 are welded to the first connector 31; a second connector 32 is placed on the other side of the pole piece assembly 100, and all the positive pole tabs 22 are welded to the second connector 32; wherein the distance of the first connector 31 above the top surface of the pole piece assembly 100 is set to H1, and the distance of the second connector 32 above the top surface of the pole piece assembly 100 is set to H2;

[0166] The portion of the first connector 31 that is higher than the top surface of the pole piece 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 pole piece assembly 100 is bent and welded to the cover plate 310 .

[0167] The above is a detailed introduction to the embodiments of the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for technicians in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A pole piece assembly for a battery, characterized in that: The pole piece assembly comprises: A plurality of negative electrode sheets, each of which comprises 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; A plurality of positive electrode sheets, each of which comprises 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; A plurality of separators, a plurality of negative electrode coating parts, a plurality of separators and a plurality of positive electrode coating parts are stacked and arranged alternately, and a corresponding separator is arranged between each negative electrode coating part and the corresponding positive electrode coating part.

2. The pole piece assembly according to claim 1, characterized in that: The pole piece assembly includes a plurality of stacked pole piece group units, the plurality of pole piece group units are stacked, the stacking direction is set along the longitudinal axis direction of the pole piece assembly, and each pole piece group unit includes a first diaphragm, the negative pole piece, a second diaphragm and the positive pole piece that are stacked.

3. The pole piece assembly according to claim 1, characterized in that: The separator includes a separator substrate and solid electrolyte layers disposed on two opposite surfaces of the separator substrate.

4. The pole piece assembly according to claim 1, characterized in that: The negative electrode plate is configured as a circular plate, and the diameter of the negative electrode plate is configured as φA. The positive electrode plate is configured as a circular plate, and the diameter of the positive electrode plate is configured as φB, wherein φA is greater than φB.

5. The pole piece assembly according to claim 4, characterized in that: The difference between φA and φB is not less than 0.3mm, and the difference between φA and φB is not greater than 1mm.

6. The pole piece assembly according to claim 4, characterized in that: The negative electrode tab or the positive electrode tab is configured as a fan-shaped piece arranged on one side of the circular pole piece, the arc length of the fan-shaped piece is L, and the calculation formula of L is 2×R×π×(α / 360°), wherein R is the radius of the circular pole piece, α is the angle formed by the line connecting the two ends of the fan-shaped piece and the center of the circle where the circular pole piece is located, and α is set to 10°~60°.

7. The pole piece assembly according to claim 1, characterized in that: The negative electrode tab comprises a first folding section, and a folding angle β is formed between the first folding section and the longitudinal axis of the electrode assembly, and the β is set to 3° to 10°; And / or, the positive electrode tab includes a second folding section, and a folding angle γ is formed between the second folding section and the longitudinal axis of the pole piece assembly, and the folding angle γ is set to 3° to 10°.

8. The pole piece assembly according to claim 2, characterized in that: The total thickness of the pole piece group unit is T0, 0.2mm≤T0≤1mm.

9. The pole piece assembly according to claim 2, characterized in that: The pole piece assembly includes N pole piece group units, each of which includes a corresponding negative electrode tab and a corresponding positive electrode tab. The pole piece assembly also includes a first connector and a second connector, the first connector is used to connect at least N negative electrode tabs, and the second connector is used to connect at least N positive electrode tabs, where N is a positive integer.

10. The pole piece assembly according to claim 9, characterized in that: The orthographic projections of the N negative electrode tabs along the longitudinal axis of the electrode assembly are located on the first connecting member, and the orthographic projections of the N positive electrode tabs along the longitudinal axis of the electrode assembly are located on the second connecting member.

11. The pole piece assembly according to claim 9, characterized in that: The thickness of the first connecting member is T1, 0.08 mm ≤ T1 ≤ 0.15 mm; and / or the thickness of the second connecting member is T2, 0.10 mm ≤ T2 ≤ 0.25 mm.

12. The pole piece assembly according to claim 9, characterized in that: The N negative electrode tabs and the N positive electrode tabs are configured to be folded toward a first direction; Alternatively, one of the N negative electrode tabs and the N positive electrode tabs is configured to be folded toward the first direction, and another one of the N negative electrode tabs and the N positive electrode tabs is configured to be folded toward a second direction, wherein the first direction and the second direction are opposite.

13. A cylindrical battery, characterized in that: The cylindrical battery comprises a shell, and a pole piece assembly disposed inside the shell, wherein the pole piece assembly comprises the pole piece assembly according to any one of claims 1 to 12.

14. The cylindrical battery according to claim 13, characterized in that: The pole piece assembly includes N pole piece group units, each of which includes a negative pole lug and a positive pole lug. The pole piece assembly also includes a first connector and a second connector, the first connector is used to connect the N negative pole lugs, the second connector is used to connect the N positive pole lugs, and the first connector and the second connector are arranged at intervals.

15. The cylindrical battery according to claim 14, characterized in that: The cylindrical battery further includes a negative electrode adapter, the electrode assembly includes a first negative electrode tab, the first negative electrode tab includes a first bending section, the first connector includes a second bending section, the second bending section, the first bending section and the negative electrode adapter are sequentially electrically connected and stacked on the top surface of the electrode assembly; and / or, The cylindrical battery also includes a positive electrode insulating member, the pole piece assembly includes a first positive electrode tab, the first positive electrode tab includes a third bending section, the second connecting member includes a fourth bending section, the fourth bending section, the third bending section and the positive electrode insulating member are sequentially stacked on the top surface of the pole piece assembly.

16. The cylindrical battery according to claim 15, characterized in that: The cylindrical battery further includes a positive electrode adapter, the electrode assembly includes a first positive electrode tab, the first positive electrode tab includes a third bending section, the second connector includes a fourth bending section, the fourth bending section, the third bending section and the positive electrode adapter are sequentially electrically connected and stacked on the top surface of the electrode assembly; and / or, The cylindrical battery also includes a negative electrode insulating member, the pole piece assembly includes a first negative electrode tab, the first negative electrode tab includes a first bending section, the first connecting member includes a second bending section, the second bending section, the first bending section and the negative electrode insulating member are electrically connected in sequence and stacked on the top surface of the pole piece assembly.

17. The cylindrical battery according to claim 16, characterized in that: The length of the second bending section is set to H1, the length of the fourth bending section is set to H2, the length of the negative electrode adapter plate is set to B1, and the radius of the electrode assembly is set to R1, wherein R1 / 3≤H1≤R1 / 2, and / or R1 / 3≤H2≤R1 / 2, and / or R1≤B1≤3R1 / 2.

18. The cylindrical battery according to claim 14, characterized in that: The cylindrical battery further includes a negative electrode adapter, the electrode assembly includes a first negative electrode tab, the first negative electrode tab includes a first bending section, the first connector includes a second bending section, the second bending section, the first bending section and the negative electrode adapter are sequentially electrically connected and stacked on the top surface of the electrode assembly; and / or, The cylindrical battery also includes a positive electrode adapter plate, the electrode assembly includes a second positive electrode ear located at the bottom end of the electrode assembly, the second positive electrode ear includes a fifth bending section, the second connecting member includes a sixth bending section, the sixth bending section, the fifth bending section and the positive electrode adapter plate are electrically connected in sequence and stacked on the bottom end surface of the electrode assembly.

19. The cylindrical battery according to claim 14, characterized in that: The cylindrical battery includes a positive electrode adapter, the electrode assembly includes a first positive electrode tab, the first positive electrode tab includes a third bending section, the second connector includes a fourth bending section, the fourth bending section, the third bending section and the positive electrode adapter are electrically connected in sequence and stacked on the top surface of the electrode assembly; and / or, The cylindrical battery also includes a negative electrode adapter plate, the electrode assembly includes a second negative electrode tab located at the bottom end of the electrode assembly, the second negative electrode tab includes a seventh bending segment, the first connecting member includes an eighth bending segment, the eighth bending segment, the seventh bending segment and the negative electrode adapter plate are electrically connected in sequence and stacked on the bottom end surface of the electrode assembly.

20. The cylindrical battery according to claim 14, characterized in that: The cylindrical battery includes an insulating film, a portion of the insulating film is disposed between the first connector and the housing, and another portion of the insulating film is disposed between the second connector and the housing.

21. A battery module, characterized in that: The battery module includes a plurality of batteries, and the batteries are configured as cylindrical batteries according to any one of claims 13 to 20.

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