An embedded self-protection current collector structure

Abstract

The utility model relates to big cylindrical lithium ion battery, concretely relates to a kind of embedded self-protection current collecting plate structure, including the same material as the current collecting plate of battery positive position, welding boss and flow guide mechanism, current collecting plate is six prism plate and is formed six prism snowflake structure, the center hole is formed at the center of current collecting plate, welding boss is set in the center hole, flow guide mechanism includes 3-12 flow guides, flow guide and welding boss and current collecting plate are connected, each flow guide is evenly distributed along the circumference and is radiated around welding boss, similar six prism snowflake in appearance, design has the pole lug welding groove of convenient and pole lug welding, the welding boss of convenient and battery shell welding and high reliability short-circuit self-protection fuse mechanism flow guide, can real-time perception outer short-circuit state, and make response quickly, cut off or limit short-circuit current, provide initiative protection from battery internal key component level, make up the deficiency of existing protection means, provide solid guarantee for the safe application of big cylindrical lithium ion battery.

Description

Technical Field

[0001] This utility model relates to a large cylindrical lithium-ion battery, specifically to an embedded self-protected current collector structure. Background Technology

[0002] In fields such as new energy vehicles and energy storage systems, 46-series large cylindrical cells are widely used due to their high energy density and power density characteristics (≥20Ah per cell, <10mΩ internal resistance) and good structural stability. However, this type of cell faces a severe risk of external short circuit (ESC). When an external short circuit occurs, the instantaneous current can reach over 1000A, and the internal temperature can exceed 200℃ within milliseconds, far exceeding the response limit of traditional protection devices. This can easily lead to electrolyte decomposition, SEI film rupture, and even serious safety accidents such as fire and explosion, posing a significant threat to equipment safety and personnel lives. Therefore, it is crucial to develop external short circuit self-protection technology adapted to 46 cylindrical cells.

[0003] Currently, industry-wide protection measures for external short circuits cover system-level, material-level, and structural-level solutions, but all have significant shortcomings. System-level battery management systems (BMS) disconnect circuits by monitoring voltage and current parameters in real time; however, limited by signal acquisition cycles (10-100ms) and loop delays, the overall response time exceeds 200ms, failing to intercept μs-level surge currents at the initial stage of a short circuit. Furthermore, misjudgments or delayed responses are prone to occur under complex operating conditions, and the additional hardware and software configurations increase system cost and complexity. Among material-level protection devices, PTCs and fuses rely on thermal triggering mechanisms; their 100-200ms response delay makes it difficult to suppress ultra-high rate short circuits (≥30C). After a fuse blows, the battery is rendered unusable. The critical temperature and resistance change rate of PTCs cannot accurately match the multi-condition requirements of 46mm cells. Current interruption devices (CIDs) are constrained by a 46mm diameter and have a diaphragm thickness ≤0.1mm. After long-term use, the trigger threshold drifts by more than ±30%, and the non-resettable characteristic increases the cell scrap rate by 0.5%. In terms of structural optimization and passive protection, although the multi-tab design reduces the local current density, the 15% reduction in internal resistance actually increases the peak short-circuit current. Passive measures such as explosion-proof valves can only intervene after the fact. When starting up, the battery has accumulated ≥80kJ of heat energy, which poses a risk of secondary thermal runaway and causes irreversible damage. Especially in low-impedance short-circuit scenarios of no more than 5mΩ, cell-level protection devices and BMS cannot operate effectively, forming a multi-scale protection gap.

[0004] In summary, existing technologies have significant shortcomings in terms of timeliness, flexibility, reliability, and damage control, making it difficult to meet the external short-circuit protection requirements of 46mm cylindrical cells. A new technology solution with rapid response and adaptive operating conditions is urgently needed. Therefore, developing a current collector with external short-circuit self-protection function is imperative. This current collector should be able to sense the external short-circuit state in real time and respond quickly, cutting off or limiting the short-circuit current, providing active protection at the level of critical internal battery components. This will compensate for the deficiencies of existing protection methods and provide a solid guarantee for the safe application of large cylindrical lithium-ion batteries. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide an embedded self-protected current collector structure and a safety solution for high-capacity cylindrical cells.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: an embedded self-protecting collector plate structure, including a collector plate, a welding boss and a flow guiding mechanism. The collector plate includes 6 ribs, each rib is provided with a tab welding groove, each rib is evenly distributed around a preset center along the circumference and forms a hexagonal snowflake shape, the inner ends of adjacent ribs are connected and a central hole is formed at the preset center, the welding boss is set in the central hole, and the flow guiding mechanism includes at least 3 flow guides, each flow guide is distributed around the welding boss along the circumference and connected to the welding boss and the collector plate.

[0007] As an optional technical solution of this utility model, each fluid guide is radially and uniformly distributed around the welding boss in the circumferential direction.

[0008] As an optional technical solution of this utility model, the number of guides is 3-12.

[0009] As an optional technical solution of this utility model, the cross-section of the guide fluid is polygonal, and chamfers are provided at the corners of the guide fluid.

[0010] As an optional technical solution of this utility model, the width of the cross-section of the fluid guide is 1mm-2mm and the cross-sectional area is 0.5mm². 2 -1mm 2 The chamfer of the fluid guide is 0.1mm.

[0011] As an optional technical solution of this utility model, the outer diameter of the collector plate is 46mm, the thickness of each rib plate is 0.1mm-1.5mm, the depth of the electrode lug welding groove is 0.1mm-0.3mm, and the thickness of the welding boss is 0.1mm-0.2mm.

[0012] As an optional technical solution of this utility model, the materials of the current collector, welding boss and current guiding mechanism are the same as those of the positive electrode potential.

[0013] As an optional technical solution of this utility model, the collector plate, welding boss and flow guiding mechanism are made of aluminum, and the surface has an oxide film with a thickness of 1μm-10μm and a surface roughness of no more than 0.8μm.

[0014] Compared with the prior art, the advantages of this utility model are as follows: 1. The current collector structure of this utility model adopts a hexagonal snowflake-shaped current collector and a radial hollow current guiding mechanism, which improves the uniformity of current density distribution by 60%. The product is compatible with the positive electrode potential of the battery, fundamentally eliminating the risk of corrosion from welding dissimilar metals. This geometric topology and material combination forms an irreplaceable technical barrier under the diameter constraint of 46 series battery cells. 2. The radially hollowed-out flow guiding mechanism dynamically matches the 0.5-50mΩ short-circuit impedance scenario through the difference in cross-sectional area of ​​3-12 flow guides, triggers the high current threshold, and completes the fuse breaking within 5ms, which is 15 times faster than the traditional solution. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the embedded self-protecting collector disk structure; Figure 2 The test data are for the experimental group and each control group; Figure 3 This is a diagram showing the results of the room temperature external short-circuit test for the experimental group; In the diagram: 1. Rib plate, 2. Welding boss, 3. Electrode welding groove, 4. Fluid guide. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model. Example

[0018] like Figure 1As shown, an embedded self-protecting current collector structure includes a current collector, a welding boss 2, and a current guiding mechanism. The current collector includes six prism plates 1, each with a welding groove 3 suitable for welding with a tab. Each prism plate 1 is evenly distributed around a preset center in a hexagonal snowflake-shaped structure. The end of the prism plate 1 closest to the preset center is its inner end, and the end furthest from the preset center is its outer end. The inner ends of adjacent prism plates 1 are connected. Each prism plate 1 forms a central hole at the preset center. The welding boss 2 is located at the central hole and is suitable for welding with the battery cell casing. The current guiding mechanism includes at least three current guides 4, each distributed around the welding boss 2 in a circumferential direction. The two ends of each current guide are connected to the welding boss 2 and the current collector, respectively.

[0019] Preferably, there are 3-12 guide bodies 4, with an included angle of 30°-120° between adjacent guide bodies 4. Each guide body 4 is radially and uniformly distributed around the welding boss 2 in the circumferential direction, and there are gaps between adjacent guide bodies 4, forming a radially hollowed-out guide mechanism. The guide body 4 can be a rod-shaped structure with a polygonal cross-section. In this case, the outer surface of the guide body 4 is chamfered at each corner along the axial direction to avoid stress concentration; the guide body 4 can also be a rod-shaped structure with a circular, elliptical, or other cross-sectional shapes.

[0020] The current collector, welding boss 2, and current guiding mechanism are all made of the same material as the positive electrode of the battery, which can eliminate the risk of corrosion from welding dissimilar metals. The current collector, welding boss 2, and current guiding mechanism are preferably made of aluminum with a conductivity of 35 MS / m. The surfaces of the current collector, welding boss 2, and current guiding mechanism are all provided with an oxide film with a thickness of 1μm-10μm and a surface roughness of no more than 0.8μm to optimize the welding cross section.

[0021] The current collector structure of this embodiment can be adapted to cylindrical batteries with diameters ranging from 20mm to 65mm. Based on the diameter of the cylindrical battery, by selecting an appropriate number of guide fluids 4 and guide fluids 4 with appropriate cross-sectional areas, the current guiding mechanism is made to correspond to the cylindrical battery. The current collector with a hexagonal snowflake-shaped topology design can be optimized for different short-circuit scenarios.

[0022] The current-guiding mechanism formed by multiple conductors 4 has a multi-stage fusing effect. Working in conjunction with the hexagonal snowflake-shaped topology of the current collector, it can actively interrupt the current path at the moment of a battery short circuit (≤5ms), improving battery safety while remaining compatible with cell manufacturing processes and long-term cycle stability. Furthermore, the hexagonal snowflake-shaped topology of the current collector and the radially perforated current-guiding mechanism can optimize the battery current distribution uniformity by up to 60%. Combined with the electrode welding groove 3 and welding boss 2, it achieves high-strength welding with the battery's positive position, electrode group, and electrode tabs. The laser welding penetration consistency error is ≤5%, and the contact resistance is reduced by 12%. By selecting an appropriate number of conductors 4, an impedance range of 0.5-50mΩ can be covered, triggering a high threshold current of 800A-1500A, ensuring that over 80% of the short-circuit energy is dissipated by the current-guiding mechanism, and the cell body temperature rise is ≤10℃.

[0023] The current collector structure in this embodiment is based on material-structure collaborative innovation. When applied to 46-series batteries, this current collector structure simultaneously achieves millisecond-level cutoff, no mechanical fatigue threshold drift, and full impedance scenario coverage under the spatial constraint of a 46mm diameter, systematically breaking through the bottleneck of external short-circuit protection for high-capacity cylindrical cells.

[0024] As a preferred example, the cross-section of the conductor 4 is polygonal, with a width of 1mm-2mm and a cross-sectional area of ​​0.5mm²-1mm², and a chamfer of 0.1mm. The outer diameter of the current collector is 46mm, the thickness of each rib plate 1 is 0.1mm-1.5mm, the depth of the electrode welding groove 3 is 0.1mm-0.3mm, and the thickness of the welding boss 2 is 0.1mm-0.2mm. This example of the current collector structure can be directly integrated into the 46-series battery cell without additional installation space. The welding boss 2 is welded to the battery cell shell, and the current collector is welded to the electrode. Actual testing shows that the battery cell using this current collector structure has a trigger time ≤3ms in a low-impedance short-circuit (5mΩ) scenario, which is 15 times faster than the traditional PTC solution, and there is no threshold drift phenomenon after long-term cycling, completely solving the failure risk of mechanical protection devices due to metal fatigue.

[0025] The current collector structure in this embodiment significantly improves the safety and economy of high-capacity cylindrical cells: millisecond-level cutoff capability avoids chain reactions caused by thermal runaway; the fully enclosed embedded design requires no modification to existing packaging processes, achieving mass production compatibility of over 95%. Currently, this technology has passed pilot-scale verification with a yield of ≥98%, possessing mature conditions for large-scale adoption in the production of large cylindrical batteries such as 4680 and 4695, providing a universal safety solution for high-energy-density battery systems.

[0026] Taking the 4680 cylindrical battery cell with the current collector structure applied in this embodiment as an example, the specific implementation effect of this embodiment will be further explained in detail through ACR, DCR, rate capability, and room temperature external short circuit test, as follows: (1) One or more cells with the number of current guiding mechanisms set to 3 are defined as the experimental group; the experimental results show that the current collector structure of this embodiment does not have a significant impact on the internal resistance of the cell; in the external short circuit test, the cell meets the test standard and no fire occurs. The highest temperature on the surface of the middle part of the cell is 30°C. The rate test shows that the maximum allowable discharge rate of the cell in this experimental group is consistent with that of the control group, and the rate temperature rise is not significantly different from that of the control group. The experimental data show that the design scheme does not have a negative impact on the rate performance of the cell; (2) One or more cells with a current-guiding mechanism of 6 were defined as control group 1. Experimental data showed that the current collector structure of this embodiment did not have a significant impact on the internal resistance of the cells; however, the cells failed the external short-circuit test and caught fire. Rate performance test showed that the maximum allowable discharge rate of control group 1 cells was 4C, and the corresponding rate temperature rise was 36℃. (3) One or more cells with a current guiding mechanism of 9 are defined as control group 2, and one or more cells with a current guiding mechanism of 12 are defined as control group 3. The test results show that the current collector structure of this embodiment does not have a significant effect on the internal resistance of the cells. However, in the external short circuit test, control group 2 and control group 3 are the same as control group 1, and both showed fire phenomenon. The rate performance test shows that the maximum allowable discharge rate of the two groups of cells is 4C, and the corresponding rate temperature rise is 37℃ and 35℃, respectively. The test data of the experimental group and each control group are as follows: Figure 2 As shown, Figure 2 The guide area refers to the sum of the cross-sectional areas of each guide fluid 4. Test data proves that... Figure 2 Test data shows that the internal resistance of the cells in the experimental group, control group 1, control group 2, and control group 3 using the current collector structure of this embodiment was not affected. The experimental group did not catch fire when short-circuited, with a maximum temperature of 30°C and a rate performance consistent with the control group of 4C. All control groups caught fire when short-circuited, with a maximum discharge rate of 4C and a temperature rise of 35-37°C. Figure 3 This is a diagram showing the results of the room temperature external short-circuit test for the experimental group, including voltage changes, current changes, cell casing temperature changes, and cell positive terminal temperature changes. Figure 3 As shown.

[0027] In this specification, the terms "an embodiment," "example," "specific example," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present 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.

[0028] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. An embedded self-protecting current collector structure, characterized in that: The device includes a flow collecting plate, a welding boss (2), and a flow guiding mechanism. The flow collecting plate includes six prism plates (1), each prism plate (1) is provided with a tab welding groove (3), each prism plate (1) is evenly distributed around a preset center in the circumferential direction and forms a hexagonal snowflake shape, the inner ends of adjacent prism plates (1) are connected and a central hole is formed at the preset center, the welding boss (2) is set in the central hole, and the flow guiding mechanism includes at least three flow guides (4), each flow guide (4) is distributed around the welding boss (2) in the circumferential direction and is connected to the welding boss (2) and the flow collecting plate.

2. The embedded self-protecting current collector structure according to claim 1, characterized in that: Each fluid guide (4) is radially and uniformly distributed around the welding boss (2) in the circumferential direction.

3. The embedded self-protecting current collector structure according to claim 2, characterized in that: The number of guides (4) is 3-12.

4. The embedded self-protecting current collector structure according to claim 3, characterized in that: The cross-section of the guide fluid (4) is polygonal, and chamfers are set at the corners of the guide fluid (4).

5. The embedded self-protecting current collector structure according to claim 4, characterized in that: The width of the cross-section of the fluid conductor (4) is 1mm-2mm and the cross-sectional area is 0.5mm². 2 -1mm 2 The chamfer of the fluid guide (4) is 0.1 mm.

6. The embedded self-protecting current collector structure according to claim 5, characterized in that: The outer diameter of the collector plate is 46mm, the thickness of each rib plate (1) is 0.1mm-1.5mm, the depth of the electrode lug welding groove (3) is 0.1mm-0.3mm, and the thickness of the welding boss (2) is 0.1mm-0.2mm.

7. An embedded self-protecting current collector structure according to any one of claims 1-6, characterized in that: The materials of the collector plate, welding boss (2) and the flow guiding mechanism are the same as those of the positive electrode potential.

8. The embedded self-protecting current collector structure according to claim 7, characterized in that: The collector plate, welding boss (2) and flow guiding mechanism are made of aluminum and have an oxide film with a thickness of 1μm-10μm and a surface roughness of no more than 0.8μm.

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