Positive tab connecting structure of high-magnification full-tab power battery

Abstract

The invention discloses a positive tab connecting structure of a high-magnification full-tab power battery, which belongs to the field of power battery manufacturing, and is characterized in that a positive upper confluence sheet and a positive lower confluence sheet adopt an annular insertion mode, and compared with the section of a current conductor of a conventional battery tab, the current conductor section of the positive tab is greatly improved; the resistance of the positive pole lug is greatly reduced, and the problem of heating of the pole lug in the high-rate charging and discharging process of the battery is solved. The lithium ion battery mainly comprises a positive electrode cap assembly and a battery cell, the positive electrode cap assembly is connected with a positive electrode upper bus sheet, the battery cell is connected with a positive electrode lower bus sheet, and the positive electrode upper bus sheet is connected with the positive electrode lower bus sheet in an inserted manner. The invention is mainly used for positive tab connection of a full-tab power battery.

Description

Technical Field

[0001] The present invention relates to the field of power battery manufacturing, and in particular to a positive pole ear connection structure of a high-rate full-pole ear power battery. Background Art

[0002] With the development of the new energy industry, higher charging and discharging rate requirements are put forward for power batteries, which promotes the research and development of high-rate battery technology. At present, high-rate lithium battery cells are widely used in aerial photography drones, agricultural plant protection drones, emergency starting power supplies, model aircraft, power tools and other products that require high-rate discharge.

[0003] Research and improvement of the charge and discharge rate performance of lithium-ion batteries mainly focus on improving the migration speed of lithium ions and reducing the internal resistance of the battery. The lead-out tabs of the current collectors of the positive and negative electrodes are the carriers for the lithium-ion battery to transfer electrical energy to the outside world. The resistance value of the tabs has a great influence on the rate performance of the battery. Too large a resistance value of the tabs will cause serious self-heating, and at the same time cause the tabs to have too large a partial pressure, resulting in a reduction in the battery output voltage. The rate performance of lithium-ion batteries can be improved by changing the material, size, lead-out method, and connection process of the current collector lead-out tabs.

[0004] The full-pole ear structure is an important method for lithium-ion power batteries to achieve high-rate performance, and lithium-ion battery manufacturers have conducted a lot of research on it. For example, a full-pole ear battery with announcement number CN219419440U has a positive ear whose area increases from the inside to the outside and whose height increases successively. After winding, all positive ear units are pressed flat to the cross section of the winding core. The positive ear units of the outer circle cover the positive ear units of the inner circle layer by layer, and form a comprehensive physical contact with the top of the steel shell of the battery to reduce the ear resistance and improve the battery rate. For example, a full-pole ear 38120 cylindrical battery structure with announcement number CN118367234A, the positive and negative copper and aluminum foils are flattened and welded to the collector plate, and then groove rolling, spot bottom welding, liquid injection, and sealing assembly are performed. For example, in a method for installing a collector plate of a full-tab battery with publication number CN118371924A, a plurality of first welding grooves are extruded on the full-tab end face of the battery cell; welding protrusions matching the first welding grooves are respectively formed on the surfaces of two collector plates; and the two collector plates are respectively covered on the full-tab end face of the battery cell and welded.

[0005] The above technical scheme adopts the method of stacking or flattening the tabs to lead the positive and negative current collectors to the positive and negative end surfaces, which increases the current conduction cross-section and improves the connection reliability between the current collectors and the current collector disks. However, it does not specifically explain how the positive and negative current collector disks are connected to the positive and negative electrodes of the battery, especially how the positive current collector disk is connected to the positive electrode cap. The reliable connection between the positive current collector disk and the positive electrode cap is precisely the difficulty in the production of high-rate full-tab power batteries.

[0006] After the battery cell is wound and formed, the positive and negative ends of the battery cell can be kneaded into disc-shaped positive and negative end surfaces with a certain thickness through flattening equipment, and the positive and negative ends of the battery cell are welded to the collector plates. The periphery of the battery cell end with the collector plate welded is insulated and then loaded into the battery casing. The general practice is that the negative electrode of the battery cell is at the bottom of the casing, and the negative electrode collector plate is fixed to the bottom of the casing by spot welding or laser welding. The positive electrode is connected to the positive electrode cap by laser welding with an aluminum strip or a nickel strip. The advantage of this method is that it is easy to operate, but the cross-section of the aluminum strip or the nickel strip is too small, generally around 3mm. 2 Below, although the battery cell uses the full-ear flattening technology, the cross-section of the positive electrode connecting belt is too small, and the conduction current is limited. When the battery is charged and discharged at a high rate, it will cause the connecting belt with a small conduction cross-section to heat up. Another method is to directly press the positive electrode collector plate with the positive electrode cap to lead out the positive electrode, but the force of the press is difficult to control, and the deformation of the positive electrode cap, collector plate or battery cell can easily lead to loose contact surface, which may cause the contact resistance of the press surface to be too large. Summary of the invention

[0007] The purpose of the present invention is to provide a positive electrode tab connection structure for a high-rate full-tab power battery, in which the positive electrode upper busbar and the positive electrode lower busbar are connected in a ring-shaped manner, which greatly improves the positive electrode tab flow conduction cross-section compared with the conventional battery tab flow conduction cross-section; greatly reduces the positive electrode tab resistance, and reduces the tab heating problem during high-rate charging and discharging of the battery.

[0008] The present invention is achieved through the following technical solutions:

[0009] A positive electrode ear connection structure of a high-rate full-ear power battery comprises a positive electrode cap assembly and a battery cell, wherein the positive electrode cap assembly is connected to an upper positive electrode busbar, the battery cell is connected to a lower positive electrode busbar, and the upper positive electrode busbar is plug-connected to the lower positive electrode busbar.

[0010] Furthermore, the positive upper busbar includes an upper convex plate bending portion arranged in a ring shape, and upper busbar plates are extended along both sides of the upper convex plate bending portion body, and a through hole is opened at the center of the upper busbar plate located on the inner side of the upper convex plate bending portion; the positive lower busbar includes an inner convex plate bending portion arranged in a ring shape and an outer convex plate bending portion arranged in a ring shape, and a mounting groove is formed between the inner convex plate bending portion and the outer convex plate bending portion, and lower busbar plates are extended on the inner side of the body of the inner convex plate bending portion, between the inner convex plate bending portion and the body of the outer convex plate bending portion, and on the outer side of the body of the outer convex plate bending portion, and the upper convex plate bending portion is inserted and installed in the mounting groove.

[0011] Furthermore, adjacent sides of the inner convex plate bending portion and the outer convex plate bending portion are provided with bending convex walls, and the bending convex walls on both sides are used to clamp the two side walls of the upper convex plate bending portion.

[0012] Furthermore, the inner convex plate bending portion and the outer convex plate bending portion are both provided with openings spaced apart at the same angle, and the openings separate the inner convex plate bending portion and the outer convex plate bending portion. When the positive upper busbar is inserted into the positive lower busbar, the positive lower busbar has a deformation margin to avoid local poor contact between the positive upper busbar and the positive lower busbar due to processing errors.

[0013] Furthermore, the reserved gap for the insertion height between the positive upper busbar and the positive lower busbar is h, 0.2mm≤h≤0.4mm, which provides a certain error range for the crimping of the battery positive cap assembly.

[0014] Furthermore, the height of the bent convex wall is greater than twice the thickness of the lower busbar of the positive electrode, so as to ensure that the clamping surface has sufficient flow conduction area.

[0015] Furthermore, the width of the male connector of the bent portion of the upper convex plate is W2, the width of the female connector of the mounting groove is W1, and 0.02mm≤W2-W1≤0.1mm.

[0016] Furthermore, the positive electrode upper busbar and the positive electrode cap assembly are connected by laser welding, and the positive electrode lower busbar and the positive terminal of the battery cell are connected by laser welding.

[0017] Furthermore, the contact surface between the positive electrode upper busbar and the positive electrode lower busbar is silver-plated with a thickness of 5um-10um to reduce the contact resistance of the plug-in surface.

[0018] Furthermore, the upper busbar of the positive electrode is made of high conductivity materials such as chromium-zirconium copper or brass to improve the current conduction capability; the lower busbar of the positive electrode is made of phosphor copper or beryllium copper, which has a high elastic limit and fatigue resistance, so as to improve the clamping force of the lower busbar of the positive electrode and reduce the contact resistance of the upper and lower busbar insertion surfaces.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The positive upper busbar and the positive lower busbar are circular in structure as a whole. The annular plug-in structure composed of the upper convex plate bending portion, the inner convex plate bending portion and the outer convex plate bending portion connects the positive electrode cap to the positive electrode of the battery cell, greatly improving the conduction cross-section of the positive electrode tab; at the same time, it reduces the resistance of the positive electrode tab, and also reduces the heat generated by the tab when the battery is working at high current, which can improve the charge and discharge rate of the power battery to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the present invention;

[0022] Figure 2 It is a schematic structural diagram of the positive electrode upper busbar of the present invention;

[0023] Figure 3 It is a schematic structural diagram of the positive electrode lower busbar of the present invention;

[0024] Figure 4 It is an enlarged view of point A of the present invention;

[0025] Figure 5 It is a schematic diagram of the cooperation between the upper convex plate bending portion and the mounting groove of the present invention;

[0026] Figure 6 It is a schematic diagram of the current channel of the present invention.

[0027] In the figure: 1. positive electrode cap assembly; 2. positive electrode upper busbar; 3. positive electrode lower busbar; 4. battery cell; 5. battery casing; 6. upper busbar plate; 7. upper convex plate bending portion; 8. lower busbar plate; 9. outer convex plate bending portion; 10. inner convex plate bending portion; 11. opening; 12. bent convex wall; 13. upper welding layer; 14. lower welding layer. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] Example 1

[0030] like Figure 1 – Figure 3 As shown, a positive electrode ear connection structure of a high-rate full-ear power battery includes a positive electrode cap assembly 1, a battery shell 5 and a battery cell 4, wherein the positive electrode cap assembly 1 is connected to the positive electrode upper busbar 2, the battery cell 4 is connected to the positive electrode lower busbar 3, and the positive electrode upper busbar 2 is plug-connected with the positive electrode lower busbar 3; the positive electrode upper busbar 2 includes an upper convex plate bending portion 7 arranged in an annular shape, and upper busbar plates 6 are extended along both sides of the upper convex plate bending portion 7 body, and a through hole is opened at the center of the upper busbar plate 6 located on the inner side of the upper convex plate bending portion 7; the positive electrode lower busbar 3 includes an inner convex plate bending portion 10 arranged in an annular shape and an outer convex plate bending portion 9 arranged in an annular shape, and a through hole is formed between the inner convex plate bending portion 10 and the outer convex plate bending portion 9 The lower busbar plate 8 is extended on the inner side of the body of the inner convex plate bending part 10, between the inner convex plate bending part 10 and the outer convex plate bending part 9, and on the outer side of the body of the outer convex plate bending part 9. The upper convex plate bending part 7 is inserted and installed in the mounting groove; a through hole is opened at the center of the lower busbar plate 8 on the inner side of the body of the inner convex plate bending part 10; the positive upper busbar 2 and the positive lower busbar 3 are both integrally bent and formed (the processing technology is the existing technology), the positive upper busbar 2 and the positive cap assembly 1 are in two-way annular surface contact, the positive lower busbar 3 and the positive end of the battery cell 4 are in three-way annular surface contact, and the annular surface contact structure is adopted to form four current channels (such as Figure 6As shown, i.e., current I1, current I2, current I3 and current I4), the current conducting cross-section of the positive lower busbar 3 is 4 times the single-path annular cross-section.

[0031] Example 2

[0032] like Figure 4 – Figure 5 As shown, a positive pole ear connection structure of a high-rate full-ear power battery, the adjacent sides of the inner convex plate bending part 10 and the outer convex plate bending part 9 are provided with bending convex walls 12, and the bending convex walls 12 on both sides are used to clamp the two side walls of the upper convex plate bending part 7; the inner convex plate bending part 10 and the outer convex plate bending part 9 are both provided with openings 11 at the same angle, and the openings 11 separate the inner convex plate bending part 10 and the outer convex plate bending part 9. When the positive upper busbar 2 is inserted into the positive lower busbar 3 During the process, the lower positive busbar 3 has a deformation margin to avoid local poor contact between the upper positive busbar 2 and the lower positive busbar 3 due to processing errors; the reserved gap between the upper positive busbar 2 and the lower positive busbar 3 is h, 0.2mm≤h≤0.4mm, which provides a certain error range for the crimping of the positive cap assembly 1 of the battery; the height of the bent convex wall 12 is L, and the height of the bent convex wall 12 is greater than 2 times the thickness of the lower positive busbar 3 to ensure clamping The surface has sufficient flow guide area; the width of the plug-in sub-port of the upper convex plate bending portion 7 is W2, and the width of the plug-in female port of the mounting groove is W1, 0.02mm≤W2-W1≤0.1mm, to ensure sufficient clamping force; the positive upper busbar 2 and the positive cap assembly 1 are connected by laser welding (i.e., the upper welding layer 13), and the positive lower busbar 3 and the positive end of the battery cell 4 are connected by laser welding (i.e., the lower welding layer 14, the positive lower busbar 3 and the positive electrode of the battery cell have three welding rings The contact surface of the positive upper busbar 2 and the positive lower busbar 3 is silver-plated with a thickness of 5um-10um to reduce the contact resistance of the plug-in surface; the positive upper busbar 2 is made of high conductivity materials such as chromium zirconium copper or brass to improve the current conduction capability; the positive lower busbar 3 is made of phosphor copper or beryllium copper, which has a high elastic limit and fatigue resistance, to improve the clamping force of the positive lower busbar and reduce the contact resistance of the upper and lower busbar plug-in surfaces. The rest is the same as Example 1.

[0033] The positive upper busbar 2 and the positive lower busbar 3 are in a circular structure as a whole. The annular plug-in structure composed of the upper convex plate bend 7, the inner convex plate bend 10 and the outer convex plate bend 9 connects the positive cap to the positive electrode of the battery cell, greatly improving the current conduction cross-section of the positive pole ear. The current conduction cross-section can be increased by an order of magnitude, that is, more than 10 times. At the same time, the resistance of the positive pole ear is reduced, and the heat generated by the pole ear under high current operation of the battery is also reduced, which can improve the charge and discharge rate of the power battery to a certain extent.

[0034] The current-carrying cross section calculation of the annular plug-in method is to select a 0.4mm thick chromium-zirconium copper material for the upper busbar of the positive electrode, and a 0.4mm thick beryllium copper material for the lower busbar of the positive electrode. Figure 6 The radius R of the guide ring is about 6.5mm (taking 26650 battery cell as an example), and the current carrying area of ​​the busbar on the positive electrode is 2*6.5*3.14*0.4*2=32.6mm 2 The current-carrying cross section of the lower busbar of the positive electrode is 13*3.14*0.4*4=65.3mm 2 The conduction cross section is much larger than the current collector conductive cross section of conventional batteries, and the current conduction cross section can be increased by an order of magnitude.

Claims

1. A positive electrode tab connection structure for a high-rate full-tab power battery, comprising a positive electrode cap assembly (1) and a battery cell (4), characterized in that: The positive electrode cap assembly (1) is connected to the positive electrode upper busbar (2), the battery cell (4) is connected to the positive electrode lower busbar (3), and the positive electrode upper busbar (2) and the positive electrode lower busbar (3) are plug-connected.

2. The positive electrode ear connection structure of the high-rate full-electrode ear power battery according to claim 1, characterized in that: The positive electrode upper busbar (2) comprises an upper convex plate bending portion (7) arranged in a ring shape, and upper busbar plates (6) are extended along both sides of the upper convex plate bending portion (7) body; the positive electrode lower busbar (3) comprises an inner convex plate bending portion (10) arranged in a ring shape and an outer convex plate bending portion (9) arranged in a ring shape, and a mounting groove is formed between the inner convex plate bending portion (10) and the outer convex plate bending portion (9), and lower busbar plates (8) are extended on the inner side of the body of the inner convex plate bending portion (10), between the inner convex plate bending portion (10) and the outer convex plate bending portion (9), and on the outer side of the body of the outer convex plate bending portion (9), and the upper convex plate bending portion (7) is inserted and installed in the mounting groove.

3. The positive electrode ear connection structure of the high-rate full-electrode ear power battery according to claim 2, characterized in that: The adjacent sides of the inner convex plate bending portion (10) and the outer convex plate bending portion (9) are both provided with bending convex walls (12), and the bending convex walls (12) on both sides are used to clamp the two side walls of the upper convex plate bending portion (7).

4. The positive electrode ear connection structure of the high-rate full-electrode ear power battery according to claim 2, characterized in that: The inner convex plate bending portion (10) and the outer convex plate bending portion (9) are both provided with openings (11) spaced apart at the same angle, and the openings (11) separate the inner convex plate bending portion (10) and the outer convex plate bending portion (9). When the positive electrode upper busbar (2) is inserted into the positive electrode lower busbar (3), the positive electrode lower busbar (3) has a deformation margin to avoid local poor contact between the positive electrode upper busbar (2) and the positive electrode lower busbar (3) due to processing errors.

5. The positive electrode ear connection structure of the high-rate full-electrode ear power battery according to claim 2, characterized in that: The reserved gap for the insertion height between the positive electrode upper busbar (2) and the positive electrode lower busbar (3) is h, and 0.2 mm ≤ h ≤ 0.4 mm.

6. The positive electrode tab connection structure of the high-rate full-tab power battery according to claim 3, characterized in that: The height of the bent convex wall (12) is greater than twice the thickness of the positive electrode lower busbar (3) to ensure that the clamping surface has sufficient flow conduction area.

7. The positive electrode tab connection structure of the high-rate full-tab power battery according to claim 2, characterized in that: The width of the male connector of the upper convex plate bending portion (7) is W2, and the width of the female connector of the mounting groove is W1, 0.02mm≤W2-W1≤0.1mm.

8. The positive electrode tab connection structure of the high-rate full-tab power battery according to claim 2, characterized in that: The positive electrode upper busbar (2) and the positive electrode cap assembly (1) are connected by laser welding, and the positive electrode lower busbar (3) and the positive end of the battery cell (4) are connected by laser welding.

9. The positive electrode ear connection structure of the high-rate full-electrode ear power battery according to claim 2, characterized in that: The contact surface of the positive electrode upper busbar (2) and the positive electrode lower busbar (3) is silver-plated with a thickness of 5um-10um to reduce the contact resistance of the plug-in surface.

10. The positive electrode tab connection structure of the high-rate full-tab power battery according to claim 2, characterized in that: The positive electrode upper busbar (2) is made of chromium zirconium copper or brass to improve the current conduction capability; the positive electrode lower busbar (3) is made of phosphor copper or beryllium copper, which has a high elastic limit and fatigue resistance, so as to improve the clamping force of the positive electrode lower busbar and reduce the contact resistance of the plug-in surface of the positive electrode upper busbar (2) and the positive electrode lower busbar (3).

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