Modular series arrangement battery based on special-shaped roll core and preparation method thereof

Abstract

The application provides a kind of modularization series battery based on special-shaped roll core and its preparation method, it is related to battery technical field, including: at least two first type winding electric core, first type winding electric core has an electric connection end face;At least one second type winding electric core, second type winding electric core has two electric connection end faces, with first type winding electric core beginning, first type winding electric core end, intermediate series connection second type winding electric core;Between two adjacent winding electric cores, through the corresponding electric connection end face docking, bridge conductive part is arranged between the two electric connection end faces of docking, for selectively connecting the same polarity electrode current collector;The electrode lead-out end of first type winding electric core and second type winding electric core, the lead-out part of bridge conductive part, according to electrode polarity is connected to total positive electrode end and total negative electrode end in parallel, the application can solve the problems of existing lithium battery, such as high rate resistance, multi-tab process complexity, thin electric core stacking integration efficiency and poor reliability.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a modular series-arranged battery based on irregularly shaped cores and its preparation method. Background Technology

[0002] Lithium-ion batteries are widely used in power batteries, energy storage batteries, and other fields due to their advantages such as high energy density and long cycle life. Improving the rate performance (fast charging and discharging capability) of batteries is the core challenge in the current development of lithium-ion batteries. The high internal resistance of batteries under high current conditions is the main bottleneck restricting their rate performance. This internal resistance mainly comes from two aspects: one is the electron transport resistance in the long-range current collector, and the other is the diffusion polarization of ions in the thick electrode and electrolyte.

[0003] To reduce battery internal resistance, existing technologies primarily rely on structural improvements, such as multi-tab or all-tab designs. While these designs can reduce electron transport resistance to some extent, they are complex to manufacture and fail to fundamentally address the issues of excessively long ion diffusion paths and uneven electrolyte wetting in thick electrodes. Furthermore, traditional lithium-ion batteries are single-cell structures with only one common positive and negative electrode. Manufacturing large-capacity batteries necessitates increasing cell size or the number of layers, which further lengthens electron and ion transport paths, leading to a further decline in rate performance and thermal management. Therefore, there is an urgent need for a novel battery structure that, starting from the fundamental physical structure, can simultaneously shorten electron and ion transport paths while maintaining high reliability and manufacturing feasibility. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a modular series-arranged battery based on irregularly shaped cores and its preparation method, aiming to solve at least one problem in the background art.

[0005] This invention provides a modular series-arranged battery based on irregularly shaped winding cores, comprising: At least two Type I wound cells, each Type I wound cell having an electrical connection end face; At least one second-type wound cell, each second-type wound cell having two oppositely disposed electrical connection end faces; The first type of wound cell and the second type of wound cell are arranged sequentially along the axial direction of the battery to form a topology that starts with the first type of wound cell, ends with the first type of wound cell, and is connected in series with at least one second type of wound cell in between. Two adjacent wound cells are electrically connected by mating corresponding electrical connection end faces. A bridging conductive element is provided between the two mating electrical connection end faces to selectively connect the same polarity electrode current collectors in the two electrical connection end faces. The electrode leads of all first-type wound cells, the electrode leads of all second-type wound cells, and the leads of all the bridging conductors are connected in parallel to the total positive and total negative terminals of the battery according to their electrode polarities.

[0006] According to one aspect of the above technical solution, the second type of wound cell is formed by stacking a positive electrode sheet, a separator and a negative electrode sheet, and then starting from the middle region along the length of the stack to form two electrical connection end faces that are arranged opposite each other along the axial direction. The width of the middle region is 5mm-20mm.

[0007] According to one aspect of the above technical solution, in the central region, the positive electrode sheet and / or the negative electrode sheet are provided with a single-sided coated current collector exposed area for leading out the electrode lead-out end of the second type of wound cell, and the width of the current collector exposed area is 5mm-20mm.

[0008] According to one aspect of the above technical solution, the first type of wound cell is formed by stacking a positive electrode sheet, a separator and a negative electrode sheet, and then winding it from one end of the stack to form an electrical connection end face.

[0009] According to one aspect of the above technical solution, the bridging conductive element is a metal tab, a metal strip, or a conductive bus, the middle part of which is connected to the same polarity current collector of the end face, and the two ends extend to the outside of the end face to form the lead-out portion. The thickness of the bridging conductive element is 0.1mm-0.3mm, and the width is 3mm-10mm.

[0010] According to one aspect of the above technical solution, an insulating structure is provided between the bridging conductive element and the opposite polarity current collectors exposed in the two electrical connection end faces, wherein the insulating structure is an extended overlapping layer of insulating adhesive, insulating sheet or diaphragm.

[0011] According to one aspect of the above technical solution, the total positive terminal and the total negative terminal are respectively connected to the total positive bus and the total negative bus. The electrode leads of the first type of wound cell, the electrode leads of the second type of wound cell, and the leads of the bridging conductive component are respectively welded to the corresponding bus according to polarity. The material of the total positive bus is aluminum with a thickness of 1mm-2mm, and the material of the total negative bus is nickel or nickel-plated steel with a thickness of 0.5mm-1.5mm.

[0012] According to one aspect of the above technical solution, the bridging conductive component connecting the positive current collector is made of aluminum or aluminum alloy, and the bridging conductive component connecting the negative current collector is made of nickel, copper-nickel composite strip or nickel-plated copper strip.

[0013] Another aspect of the present invention provides a method for fabricating a modular series-arranged battery based on an irregularly shaped wound core. The method is used to fabricate the aforementioned modular series-arranged battery based on an irregularly shaped wound core, and the method includes: The positive electrode, separator, and negative electrode are aligned and stacked, and then wound from one end of the stack to produce a first type of wound cell with only one electrical connection end face. The positive electrode, separator, and negative electrode are aligned and stacked, and the winding begins from the middle region of the stack to produce a second type of wound cell with two electrical connection ends. Following a topological order that starts with a first type of wound cell and ends with a first type of wound cell, with at least one second type of wound cell connected in series in between, the wound cells are arranged sequentially along the battery axis. Align the corresponding electrical connection end faces of two adjacent wound cells with each other, and weld a bridging conductive element between the two mating electrical connection end faces. The bridging conductive element selectively connects the same polarity electrode current collectors in the two electrical connection end faces. All the electrode leads of the first type of wound cells, all the electrode leads of the second type of wound cells, and all the leads of the bridging conductive parts are connected in parallel to the total positive terminal and the total negative terminal of the battery according to their electrode polarities. The parallel-integrated cell modules are placed into the battery casing, and then liquid injection and sealing processes are performed.

[0014] Furthermore, an insulating material is applied around the connection point where the bridging conductive element is welded to the two electrical connection ends to form an insulating structure, ensuring insulation from the current collector of the opposite polarity electrode.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention introduces a second type of wound cell with dual electrical connection end faces, which is regularly combined with a first type of wound cell with a conventional single electrical connection end face to construct an internal series and external parallel circuit topology within a single cell. Internal series connection is achieved by connecting adjacent cells with the same polarity current collector through bridging conductive components, and all leads of the same polarity are connected in parallel to the main busbar. This unifies the series connection of multiple wound cells and the external parallel output within the cell, and simultaneously shortens the electron transport path and ion diffusion path from the bottom layer of physical structure, fundamentally solving the problems of long-distance electron transport and ion diffusion polarization in traditional single cells.

[0016] 2. This invention achieves a multi-tab effect within a single cell, shortening the electron transport path to the length of a single sub-wound cell (first-type wound cell, second-type wound cell), significantly reducing ohmic internal resistance and improving battery rate performance; it breaks down a large wound cell into multiple small sub-wound cells, shortening the ion solid-state diffusion path and reducing concentration polarization; at the same time, the gaps between the sub-wound cells facilitate heat dissipation and conduction, avoiding the heat accumulation problem of traditional large wound cells, reducing the temperature rise during high-rate discharge, and improving battery safety and cycle life.

[0017] 3. Compared with the traditional method of external stacking and series connection of thin cells, the present invention realizes modular series connection inside the battery, eliminating the need for additional stacking structures, improving integration efficiency and reducing connection nodes, thereby reducing the risk of connection failure. With the addition of bridging conductive components compatible with current collector materials, the low contact resistance and welding reliability of the connection are guaranteed. Combined with the setting of the insulation structure, internal short circuits can be effectively prevented, thereby improving the reliability of the battery structure and the safety of use. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the battery after encapsulation according to the present invention; Figure 2 This is a schematic diagram of the assembly of the battery of the present invention; Figure 3 This is a schematic diagram of the structure of the first type of wound battery cell of the present invention; Figure 4 This is a schematic diagram and a top cross-sectional view of the first type of wound battery cell of the present invention; Figure 5 This is a schematic diagram of the structure of the second type of wound battery cell of the present invention; Figure 6 This is a schematic diagram and a top cross-sectional view of the second type of wound battery cell of the present invention; Figure 7 The diagram shows the 3C charge-1C discharge battery cycle test results of Embodiment 1 and Comparative Example 1 of the present invention. Component symbol explanation in the attached diagram: 1. Type I wound cell, 2. Electrical connection end face, 3. Type II wound cell, 4. Negative electrode sheet, 5. Separator, 6. Positive electrode sheet, 7. Bridging conductive component, 8. Total positive bus, 9. Total negative bus, 10. Electrode lead-out end, 11. Total positive terminal, 12. Total negative terminal, 13. Battery casing, 70. The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0019] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] Please see Figures 1-6 The image shows a modular series-arranged battery based on irregularly shaped winding cores provided by the present invention, comprising: At least two first-type wound cells 1, each first-type wound cell 1 having an electrical connection end face 2; At least one second type of wound cell 3, each second type of wound cell 3 having two oppositely arranged electrical connection end faces 2; The first type of wound cell 1 and the second type of wound cell 3 are arranged sequentially along the axial direction of the battery to form a topology that starts with the first type of wound cell 1 and ends with the first type of wound cell 1, with at least one second type of wound cell 3 connected in series in between. Two adjacent wound cells are electrically connected by mating corresponding electrical connection end faces 2. A bridging conductive element 7 is provided between the two mating electrical connection end faces 2 for selectively connecting the same polarity electrode current collectors in the two electrical connection end faces 2. The electrode leads 10 of all first-type wound cells 1, the electrode leads 10 of all second-type wound cells 3, and the lead portions 70 of all the bridging conductors 7 are connected in parallel to the total positive terminal 11 and the total negative terminal 12 of the battery according to their electrode polarities.

[0022] Furthermore, the second type of wound cell 3 is formed by stacking a positive electrode 6, a separator 5, and a negative electrode 4, and then starting from the middle region along the length of the stack to form two electrical connection end faces 2 arranged opposite each other along its axial direction. Each end face includes the end of the positive electrode 6, the end of the separator 5, and the end of the negative electrode 4. The bidirectional winding with the middle region of the stack as the starting area is the core structural basis for forming the dual electrical connection end faces 2. The symmetrical middle region can ensure the uniformity of bidirectional winding. The width of the middle region is 5mm-20mm, which can avoid the reduction of the effective area of ​​active material due to the middle region being too wide, or the difficulty in positioning the winding equipment due to the middle region being too narrow.

[0023] In the central region, the positive electrode 6 and / or the negative electrode 4 are provided with a single-sided coated exposed current collector area for leading out the electrode lead-out end 10 of the second type of wound cell 3. The width of the exposed current collector area is 5mm-20mm. The positive electrode 6 and / or the negative electrode 4 adopt a single-sided coating process to form an exposed current collector area without active material coating.

[0024] Furthermore, the active material coating thickness of the positive electrode 6 is 80μm-220μm, and the active material coating thickness of the negative electrode 4 is 90μm-200μm. The active material coating thickness on both sides of the exposed area is consistent with the coating thickness of other areas of the electrode sheet.

[0025] It should be noted that the exposed area of ​​the current collector provides an effective connection surface for the subsequent welding of the electrode lead-out end 10 of the second type of wound cell 3, avoiding the influence of the active material layer on the welding conductivity and connection strength. That is, the exposed area of ​​the current collector without active material can realize the direct welding of the electrode lead-out end 10 of the second type of wound cell 3 to the corresponding busbar, improving the conductivity of the welding surface and reducing the contact resistance.

[0026] Furthermore, the first type of wound cell 1 is formed by stacking a positive electrode 6, a separator 5, and a negative electrode 4, and then winding it from one end of the stack to form an electrical connection end face 2, which includes the end of the positive electrode 6, the end of the separator 5, and the end of the negative electrode 4. The alignment error of the winding start end of the first type of wound cell 1 is ≤1mm, preferably ≤0.5mm. As the first and last connection unit of the modular series battery, the structure of its single electrical connection end face 2 can be precisely docked with the electrical connection end face 2 of the second type of wound cell 3, forming the basic topology of ABA, avoiding redundant connection nodes in the series connection. Here, A represents the first type of wound cell 1, and B represents the second type of wound cell 3. Its electrical connection end face 2 integrates the positive and negative electrodes and the end of the separator 5, which can complete the dual requirements of electrode electrical connection and ion isolation in a single docking, simplifying the assembly process.

[0027] As an example rather than a limitation, the number of winding layers of the first type of wound cell 1 can be flexibly set according to the battery capacity. By adjusting the number of winding layers to match different capacity requirements, the battery capacity can be flexibly expanded without changing the core structure of the cell, thus adapting to diverse application scenarios.

[0028] It is understandable that the number of the second type of wound cells 3 connected in series in the middle is not limited to one or two, and can be expanded to multiple according to voltage requirements, forming A-(B). n-A's topology, where n represents the number of the second type of wound cells 3 connected in series in the middle, n≥1. As the core series unit of the modular series battery, the structure of the dual-electrical connection end face 2 can realize continuous series connection with the first type or other second type of wound cells 3 on both sides, forming a multi-unit modular structure, which is the basis for realizing internal series connection of the battery.

[0029] Furthermore, adjacent wound cells are electrically connected through their opposing electrical connection end faces 2. A bridging conductive element 7 is disposed between two adjacent electrical connection end faces 2, and the bridging conductive element 7 electrically connects the electrode current collector ends of the same polarity in the two electrical connection end faces 2. An insulating structure is disposed between the bridging conductive element 7 and the electrode current collectors of opposite polarity exposed in the end face, ensuring that the bridging conductive element 7 is effectively isolated from the electrodes of opposite polarity.

[0030] Furthermore, the bridging conductive element 7 is a metal tab, metal strip, or conductive bus, with its middle part connected to the electrode current collector of the same polarity on the end face, and both ends extending outward to form lead-out portions 70. The thickness of the bridging conductive element 7 is 0.1mm-0.3mm, and its width is 3mm-10mm.

[0031] Furthermore, the bridging conductive component 7 connecting the positive current collector is made of aluminum or aluminum alloy, while the bridging conductive component 7 connecting the negative current collector is made of nickel, copper-nickel composite strip, or nickel-plated copper strip.

[0032] Furthermore, the insulating structure is an extended overlapping layer of insulating adhesive, insulating sheet, or diaphragm 5.

[0033] It should be noted that the same polarity connection of the bridging conductive element 7 can realize reliable series connection inside the wound cell, connecting it into a whole. Under the premise of ensuring that the battery voltage is consistent with that of the traditional single cell, it can achieve the equivalent effect of multiple tabs. In addition, the bridging conductive element 7 has the dual functions of internal series connection and external parallel connection. Its extended part directly serves as the electrode lead-out end 10, which can reduce the welding of additional tabs and simplify the battery structure.

[0034] Furthermore, the total positive terminal 11 and the total negative terminal 12 are respectively connected to the total positive busbar 8 and the total negative busbar 9. The electrode lead-out ends 10 of the first type of wound cell 1, the electrode lead-out ends 10 of the second type of wound cell 3, and the lead-out portions 70 of the bridging conductive element 7 are respectively welded to the corresponding busbars according to their polarities. The total positive busbar 8 is made of aluminum with a thickness of 1mm-2mm and a width of 15mm-25mm. The total negative busbar 9 is made of nickel or nickel-plated steel with a thickness of 0.5mm-1.5mm and a width of 15mm-25mm. The contact resistance of the welding point between the electrode lead-out end 10 and the corresponding busbar is ≤1mΩ, and the total resistance of the entire battery connected in parallel is ≤3mΩ.

[0035] In other words, the parallel connection of all leads 10 of the same polarity is the core of realizing the external parallel circuit topology of the battery. It can collect the current of multiple sub-wound cells (first type of wound cell and second type of wound cell) connected in series inside, and present a single positive and negative terminal to the outside, ensuring the compatibility of the battery with existing electrical equipment.

[0036] Furthermore, by using an internal series-external parallel topology, multiple independent sub-wound cells are integrated into a single battery casing 13. This modular series connection of multiple sub-wound cells within the battery simultaneously shortens the electron transport path in the electrode current collector and the ion diffusion path in the electrode and electrolyte, thus doubly reducing the battery's internal resistance and significantly improving its rate performance. The parallel structure of multiple sub-wound cells increases the contact area between the electrolyte and the electrodes and separator 5, improving electrolyte wetting efficiency and ensuring the uniformity of the electrochemical reaction. Moreover, the internal series connection reduces external connection nodes, improving the battery's integration efficiency and connection reliability. At the same time, it disperses the current among multiple sub-wound cells, resulting in more uniform heating, optimizing the battery's thermal management performance, and improving cycle life.

[0037] Accordingly, this application also provides a method for preparing a modular series-arranged battery based on irregularly shaped cores, the method comprising: steps S1-S6.

[0038] Step S1: Align and stack the positive electrode, separator, and negative electrode, and start winding from one end of the stack to obtain a first type of wound cell with only one electrical connection end face. Step S2: Align and stack the positive electrode, separator, and negative electrode, and start winding from the middle region of the stack to obtain a second type of wound cell with two electrical connection end faces. Specifically, a dedicated winding device with at least two synchronous winding needles is used to synchronously wind the electrodes from the starting point. The winding linear speed is controlled at 0.5m / s-2.0m / s, the diaphragm tension is 1.0N-2.0N with a deviation of ≤±10% on both sides, the tension of the positive and negative electrodes is 5N-15N with a deviation of ≤±15% on both sides, and the instantaneous speed difference between the two winding needles is ≤±0.5% of the rated speed.

[0039] Step S3: Arrange the winding cells sequentially along the battery axis according to the topological order of starting with the first type of winding cell and ending with the first type of winding cell, with at least one second type of winding cell connected in series in between. Step S4: Align the corresponding electrical connection end faces of two adjacent wound cells with each other, and weld a bridging conductive element between the two mating electrical connection end faces. The bridging conductive element selectively connects the same polarity electrode current collectors in the two electrical connection end faces. Specifically, the axial gap between the electrical connection end faces of two adjacent wound cells is 0.05mm-0.2mm, the maximum edge gap difference caused by the non-parallelism of the two electrical connection end faces is ≤0.05mm, and the radial offset of the center of the two electrical connection end faces is ≤±0.05mm; the main shafts of all wound cells coincide within the battery casing, and the coaxiality error of the axes of any two wound cells within the total length of the battery is ≤0.2mm, preferably ≤0.1mm.

[0040] Among them, the same polarity electrode current collectors made of aluminum or aluminum alloy are ultrasonically welded, with a welding amplitude of 30μm-70μm, a welding pressure of 0.1MPa-0.2MPa, and a welding energy of 300J-750J; the same polarity electrode current collectors made of nickel, copper-nickel composite strips, or nickel-plated copper strips are laser welded, with a welding power of 2.0kW-4.0kW, a welding speed of 100mm / s-150mm / s, and a welding energy density of 50J / mm². 2 -100J / mm 2 .

[0041] Step S5: Connect the electrode leads of all first-type wound cells, the electrode leads of all second-type wound cells, and the leads of all bridging conductive parts in parallel to the total positive and total negative terminals of the battery according to their electrode polarities. Step S6: Place the parallel-integrated cell module into the battery casing and perform liquid injection and sealing processes.

[0042] Specifically, the externally parallel integrated cell modules are placed into the battery casing, preferably a steel casing, to ensure the structural strength and sealing performance of the casing. Electrolyte injection is carried out under process conditions with an ambient dew point ≤ -35℃, and the injection volume coefficient is controlled at 1.2g / Ah-1.5g / Ah to ensure sufficient wetting of the electrolyte. Specialized equipment is used to seal the battery casing to ensure the battery's sealing performance and prevent electrolyte leakage and moisture ingress. The battery undergoes formation treatment according to the standard process for lithium-ion batteries to activate its electrochemical performance and produce a modular series battery product.

[0043] Example 1 Embodiment 1 of the present invention provides a modular series-arranged battery based on irregularly shaped winding cores, comprising: Two type I wound cells, using LiNi coated cells 0.8 Co 0.1 Mn 0.1O2 positive electrode aluminum foil, ceramic-coated polyethylene separator, and graphite-coated negative electrode copper foil are aligned and wound from one end to form two standard cylindrical Type I wound cell cores. Each Type I wound cell has blank spaces on its unique electrical connection end face for welding tabs to the positive and negative electrode foils.

[0044] Specifically, the positive electrode aluminum foil has a thickness of 13μm, a coating width of 60mm, a double-sided coating thickness of 40μm, and a total electrode length of 3000mm; the negative electrode copper foil has a thickness of 6μm, a coating width of 62mm, a double-sided coating thickness of 40μm, a total electrode length of 3300mm, and an N / P ratio of 1.08; the separator has a total thickness of 16μm (including a 9μm base film + double-sided 3.5μm ceramic coating) and a width of 66mm. The number of winding layers is 42-44, and the diameter of the wound core after forming is 19.5mm ± 0.3mm.

[0045] A type II wound cell uses the same positive electrode material and separator, and a negative electrode copper foil coated with silicon-carbon. A single-sided coating area is reserved in the middle of both the positive electrode aluminum foil and the negative electrode copper foil along their length; one side has an active material coating, and the other side is a bare foil. The single-sided coating area is 10 mm wide, 30 mm long, and has a single-sided coating thickness of 30 μm. Within this area, the active material is coated only on the side facing the separator, while the side facing away from the separator remains bare foil, forming an exposed current collector area.

[0046] Using a specialized winding device with two synchronous winding needles, the winding starts from the midpoint of the aligned area and proceeds synchronously to both sides to form a second type of wound cell with two electrical connection ends. The winding linear speed is controlled at 1.0 m / s, the diaphragm tension is 1.5 N, the tension of both positive and negative electrodes is 10 N, and the tension deviation on both sides is controlled within ±10% to complete the winding process.

[0047] The winding process forms two electrical connection faces: one electrical connection face exposes the negative current collector and leaves a blank space (approximately 12mm wide), and the other electrical connection face exposes the positive current collector and leaves a blank space (approximately 12mm wide), with a forming diameter of approximately 19.0mm-19.3mm.

[0048] Arranged in order: Type I wound cell - Type II wound cell - Type I wound cell.

[0049] First connection (between type I and type II wound cells): Align the corresponding electrical connection ends of the first type I wound cell and the second type II wound cell. Based on the material of the electrode current collector on the end-face electrode sheet, take a bridging conductive element (nickel bridging tab, 0.2mm thick, 6mm wide), and ultrasonically weld its two welded parts to the negative copper foil blank on the electrical connection end face of the type I wound cell and the negative copper foil blank on the electrical connection end face of the type II wound cell, respectively (ultrasonic welding parameters: amplitude 50μm, pressure 0.15MPa, welding energy 500J). Apply insulating adhesive around the weld points to ensure complete isolation between the bridging tab and the exposed positive aluminum foil on the two electrical connection end faces. Simultaneously, heat-press the diaphragms of the two electrical connection end faces together. The positive terminals of the two electrical connection ends are connected in the same way using bridging conductive parts (aluminum bridging tabs, 0.2 mm thick and 6 mm wide), and ultrasonic welding is used (amplitude 60 μm, pressure 0.18 MPa, energy 600 J).

[0050] Second connection (between the second type of wound cell and the first type of wound cell): Align the other electrical connection end face of the second type of wound cell with the electrical connection end face of the second type of wound cell. Take nickel bridging tabs and aluminum bridging tabs respectively to connect the negative copper foil and positive aluminum foil of the other electrical connection end face of the second type of wound cell to the copper foil and aluminum foil of the electrical connection end face of the first type of wound cell, using the same welding parameters as above.

[0051] High-precision positioning fixtures are used to ensure that the coaxiality error of the three battery cells is ≤0.1mm, the end face gap is 0.1mm, and the radial offset is ≤0.05mm.

[0052] At this point, the first type of wound cell, the second type of wound cell, and the first type of wound cell are internally connected in series through two bridging points. The positive and negative tabs of each first type of wound cell, the positive and negative tabs of each second type of wound cell, and the external leads of the two nickel / aluminum bridging tabs are all to be connected.

[0053] All positive leads (the positive tab of the first type I wound cell, the positive tab of the second type I wound cell, and the aluminum bridging tab connecting the second type I wound cell and the second type I wound cell) are arranged in parallel and laser-welded together to a single aluminum main positive busbar (1.5mm thick, 20mm wide). Laser welding parameters: power 3.0kW, speed 120mm / s.

[0054] All negative terminals (the negative tabs of the second type I wound cell, the negative tabs of the second type I wound cell, and the nickel bridging tabs connecting the first type I wound cell and the second type I wound cell) are connected to a single nickel-plated negative busbar (1.0 mm thick, 20 mm wide). Laser welding parameters: power 2.5 kW, speed 120 mm / s.

[0055] After welding, the contact resistance of each welding point is ≤0.5mΩ, and the increase in DC internal resistance of the total parallel path is ≤3% of the total internal resistance of the battery.

[0056] The integrated module is placed into the battery casing, and electrolyte is injected at a rate of 1.3 g / Ah, with an ambient dew point of -40°C. The three parallel sub-wound cells are fully wetted by the electrolyte within minutes, much faster than a single large-wound cell of the same capacity. Standard processes such as sealing and formation are then performed to obtain the finished battery.

[0057] Example 2 This embodiment is basically the same as Embodiment 1, except that two Type II wound cells are connected in series in the middle to form an ABBA topology. During fabrication, four cells are arranged sequentially: a Type I wound cell, a Type II wound cell, a Type II wound cell, and a Type I wound cell. Bridging conductors are provided between the Type I wound cell and the first Type II wound cell, between the first Type II wound cell and the second Type II wound cell, and between the second Type II wound cell and the Type I wound cell to ensure same polarity connection. All positive leads are connected in parallel to the main positive busbar, and all negative leads are connected in parallel to the main negative busbar.

[0058] Comparative Example 1 A conventional single-cell battery was prepared using the same material system, with a capacity comparable to the ABA module in Example 1.

[0059] Battery cycle life test: Under the condition of 25℃±2℃, the battery is charged to 4.2V with 3C constant current and constant voltage, and then discharged to 3.0V with 1C constant current. The charge and discharge cycles are repeated, and the discharge capacity is recorded each time to evaluate the cycle life of the battery.

[0060] like Figure 7 As shown, the battery corresponding to Example 1 can more effectively suppress capacity decay during cycling, and significantly improve the battery's cycle life and long-term stability.

[0061] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0062] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A modular series-connected battery based on irregularly shaped wound cores, characterized in that, include: At least two Type I wound cells, each Type I wound cell having an electrical connection end face; At least one type II wound cell, each type II wound cell having two opposing electrical connection end faces. The first type of wound cell and the second type of wound cell are arranged sequentially along the axial direction of the battery to form a topology that starts with the first type of wound cell, ends with the first type of wound cell, and has at least one second type of wound cell arranged in series in between. Two adjacent wound cells are electrically connected by their corresponding electrical connection end faces. A bridging conductive element is provided between the two electrical connection end faces to connect the current collectors of the same polarity in the two electrical connection end faces. The electrode leads of all first-type wound cells, the electrode leads of all second-type wound cells, and the leads of all the bridging conductors are connected in parallel to the total positive and total negative terminals of the battery according to their electrode polarities. The second type of wound cell consists of a positive electrode sheet, a separator, and a negative electrode sheet stacked together, and then wound starting from the middle region along the length of the stack to form two electrical connection end faces arranged opposite each other along its axial direction. The first type of wound battery cell consists of a positive electrode sheet, a separator, and a negative electrode sheet stacked together, and then wound from one end of the stack to form an electrical connection end face. The bridging conductive component is a metal tab, a metal strip, or a conductive bus, with its middle part connected to the same polarity current collector electrode on the end face, and its two ends extending outwards from the end face to form the lead-out portion.

2. The modular series-connected battery based on irregularly shaped winding cores according to claim 1, characterized in that, The width of the central region is 5mm-20mm.

3. The modular series-connected battery based on irregularly shaped winding cores according to claim 2, characterized in that, In the central region, the positive electrode and / or the negative electrode are provided with a single-sided coated current collector exposed area for leading out the electrode lead of the second type of wound cell. The width of the current collector exposed area is 5mm-20mm.

4. The modular series-connected battery based on irregularly shaped winding cores according to claim 1, characterized in that, The thickness of the bridging conductive element is 0.1mm-0.3mm, and the width is 3mm-10mm.

5. The modular series-connected battery based on irregularly shaped winding cores according to claim 4, characterized in that, An insulating structure is provided between the bridging conductive element and the opposite polarity current collectors exposed in the two electrical connection end faces, the insulating structure including an extended overlap layer of insulating adhesive, insulating sheet or diaphragm.

6. The modular series-connected battery based on irregularly shaped winding cores according to claim 4, characterized in that, The total positive terminal and the total negative terminal are respectively connected to the total positive bus and the total negative bus. The electrode leads of the first type of wound cell, the electrode leads of the second type of wound cell, and the leads of the bridging conductive component are respectively welded to the corresponding bus according to polarity. The total positive bus is made of aluminum with a thickness of 1mm-2mm and a width of 15mm-25mm. The total negative bus is made of nickel or nickel-plated steel with a thickness of 0.5mm-1.5mm and a width of 15mm-25mm.

7. The modular series-connected battery based on irregularly shaped winding cores according to claim 4, characterized in that, The bridging conductive component connecting the positive current collector is made of aluminum or aluminum alloy, while the bridging conductive component connecting the negative current collector is made of nickel, copper-nickel composite strip, or nickel-plated copper strip.

8. A method for preparing a modular series-connected battery based on irregularly shaped wound cores, used to prepare the modular series-connected battery based on irregularly shaped wound cores as described in any one of claims 1-7, characterized in that, The method includes: The positive electrode, separator, and negative electrode are aligned and stacked, and then wound from one end of the stack to produce a first type of wound cell with only one electrical connection end face. The positive electrode, separator, and negative electrode are aligned and stacked, and the winding begins from the middle region of the stack to produce a second type of wound cell with two electrical connection ends. Following a topological order that starts with a first type of wound cell and ends with a first type of wound cell, with at least one second type of wound cell connected in series in between, the wound cells are arranged sequentially along the battery axis. Align the corresponding electrical connection end faces of two adjacent wound cells with each other, and weld a bridging conductive component between the two mating electrical connection end faces. The bridging conductive component connects the same polarity electrode current collectors in the two electrical connection end faces. All the electrode leads of the first type of wound cells, all the electrode leads of the second type of wound cells, and all the leads of the bridging conductive parts are connected in parallel to the total positive terminal and the total negative terminal of the battery according to their electrode polarities. The parallel-integrated cell modules are placed into the battery casing, and then liquid injection and sealing processes are performed.

9. The method for preparing a modular series-connected battery based on an irregularly shaped core according to claim 8, characterized in that, An insulating material is applied around the connection point where the bridging conductive element is soldered to the two electrical connection ends to form an insulating structure, ensuring insulation from the current collector of the opposite polarity electrode.

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