A cylindrical lithium-ion battery

Abstract

The utility model relates to a cylindrical battery technical field, proposes a kind of cylindrical lithium ion battery, including roll core and positive current collector, wherein, the end surface area of roll core is S0;The positive current collector includes disc body and tail body, and the disc body is fixedly arranged on the roll core;One end of the tail body is integrally formed on the disc body, and it is continuously arranged with it, narrowing slot is set in the connecting place of the disc body and the tail body, and the part of the disc body and the tail body except the narrowing slot in the connecting place is narrowing part, and the area of the narrowing part is S 12 Wherein, 2%S0≤S 12 ≤3.2%S0.The utility model can reduce the processing difficulty of positive current collector and improve its assembly compatibility by setting narrowing slot in the connecting place of disc body and tail body, and by reasonably setting the area of narrowing part, the structural strength of positive current collector and the thermal runaway fusing capacity of positive current collector can be considered, so as to effectively improve the overall performance of battery.

Description

Technical Field

[0001] This utility model relates to the field of cylindrical battery technology, and in particular to a cylindrical lithium-ion battery. Background Technology

[0002] With the continuous development of new energy technologies, batteries, as high-efficiency energy storage devices, are widely used in various portable electronic products, electric vehicles, and large-scale energy storage systems. Among them, cylindrical lithium-ion batteries have gradually become one of the mainstream products in the market due to their excellent performance and high energy density. The positive current collector is a component inside the battery used to collect and conduct current, and is usually made of metal, such as aluminum. In multi-tab batteries, the positive current collector is directly welded to the positive tab to form a conductive connection. The design of the positive current collector can reduce the battery's internal resistance and improve the efficiency of electron movement, thereby enhancing the battery's power output and charge / discharge performance.

[0003] In existing technologies, in order to ensure timely melting of the current collector in the event of battery thermal runaway, thereby cutting off the current and providing safety protection for the positive current collector, a groove structure is generally set in the positive current collector. However, the area of ​​the groove directly determines the overall performance of the positive current collector. If the area of ​​the groove is too large, the structural strength of the tail body will be too low, making it prone to breakage, generating metal foreign objects and burrs, which will increase the risk of short circuit and poor K-value of the battery. If the area of ​​the groove is too small, the power-breaking capacity of the tail body melting area will decrease, and it will not be able to melt in time, thus failing to play an effective protective role and reducing the safety performance of the battery. Utility Model Content

[0004] In view of this, the present invention proposes a cylindrical lithium-ion battery, which, by reasonably setting the area of ​​the narrow section, can take into account both the structural strength of the positive electrode current collector and the thermal runaway melting capability of the positive electrode current collector, thereby effectively improving the overall performance of the battery.

[0005] The technical solution of this utility model is achieved as follows: This utility model provides a cylindrical lithium-ion battery, including a core and a positive electrode current collector, wherein,

[0006] The end face area of ​​the core is S0;

[0007] The positive current collector includes a disk body and a tail body. The disk body is fixedly mounted on the winding core. One end of the tail body is integrally formed on the disk body and continuously mounted thereon. A narrowing groove is provided at the connection between the disk body and the tail body. The portion of the connection between the disk body and the tail body excluding the narrowing groove is a narrowed portion, and the area of ​​the narrowed portion is S. 12 Where 2%S0≤S 12 ≤3.2%S0.

[0008] Based on the above technical solutions, preferably, the core is provided with a positive electrode tab, the positive electrode tab is a full electrode tab, and the disk body is connected to the positive electrode tab by welding.

[0009] The area of ​​the positive electrode tab located within the narrowing groove is S. 11 Of which, 4.6% S0≤S 11 ≤5.8%S0.

[0010] A further preferred option is 15.0mm. 2 ≤S 11 ≤19.0mm 2 6.5mm 2 ≤S 12 ≤10.4mm 2 .

[0011] Based on the above technical solutions, preferably, the width of the tail body is W. 30 The width of the narrowed portion is W 31 Of which, 42% W 30 ≤W 31 ≤58% W 30 And 2.5mm≤W 31 ≤3.5mm.

[0012] Based on the above technical solutions, preferably, the narrowing groove includes a first side line, a second side line, and a third side line, wherein the first side line, the second side line, and the third side line are all inner walls of the narrowing groove, and are arranged sequentially and continuously.

[0013] The first sideline is located on the side of the second sideline away from the tail body, and the angle between the first sideline and the second sideline is E, where 72°≤E≤88°.

[0014] More preferably, the third sideline is located on the side of the second sideline away from the disk body, and the angle between the third sideline and the second sideline is F, wherein 105°≤F≤135°.

[0015] Based on the above technical solutions, preferably, the end face radius of the core is R0, and the distance between the periphery of the core and the periphery of the disc body is L4, wherein 8.6%R0≤L4≤12.6%R0.

[0016] Based on the above technical solution, preferably, the end face radius of the core is R0, and the distance between the center point of the core end face and the narrowing portion is M. 10 Of which, 51.8% R0≤M 10 ≤57.7%R0.

[0017] More preferably, the span of the narrowing portion along the length direction of the tail body is M. 11 Among them, 11.6% R0≤M 11 ≤17.5%R0.

[0018] More preferably, the distance between the narrowed portion and the periphery of the core is M. 12 Of which, 27.8% R0≤M 12 ≤33.7%R0.

[0019] The cylindrical lithium-ion battery of this invention has the following advantages over the prior art:

[0020] (1) By opening the narrowing groove at the connection between the disk body and the tail body, the processing difficulty of the positive electrode current collector can be reduced and its assembly compatibility can be improved. By reasonably setting the area of ​​the narrowing part, the structural strength of the positive electrode current collector and the thermal runaway melting capability of the positive electrode current collector can be taken into account, thereby effectively improving the overall performance of the battery.

[0021] (2) By limiting the specifications of the narrowing groove and the narrowing section, the current carrying capacity, thermal runaway fusing performance and structural strength of the positive electrode current collector can be further balanced, and the manufacturing cost of the battery can be reduced and the energy density of the battery can be increased. Attached Figure Description

[0022] 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.

[0023] Figure 1 This is a top view of a cylindrical lithium-ion battery according to the present invention.

[0024] Figure 2 This is an enlarged view of point A in a cylindrical lithium-ion battery according to this utility model.

[0025] Figure 3 This is a top view of the narrowed groove in a cylindrical lithium-ion battery according to the present invention.

[0026] Figure 4 This is an enlarged view of point B in a cylindrical lithium-ion battery according to this utility model.

[0027] Among them: 1. Core; 11. Positive electrode tab; 2. Positive electrode current collector; 21. Disc body; 22. Tail body; 201. Narrowing groove; 2011. First side line; 2012. Second side line; 2013. Third side line; 202. Narrowing section. Detailed Implementation

[0028] The technical solutions of this utility model will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0029] The present invention relates to a cylindrical lithium-ion battery, comprising a core 1 and a positive electrode current collector 2.

[0030] The core 1 is the core component of a cylindrical lithium-ion battery, and its quality directly affects key indicators such as the performance, safety, and lifespan of the cylindrical lithium-ion battery. The core 1 is made of a positive electrode sheet, a negative electrode sheet, and a separator wound together. A positive electrode tab 11 is welded and fixed on the positive electrode sheet, and a positive current collector 2 is welded and fixed between the positive electrode tab 11 and the cap assembly, thereby realizing the electrical connection between the positive electrode sheet and the cap assembly.

[0031] like Figure 1 As shown, the positive current collector 2 includes a plate body 21 and a tail body 22. The plate body 21 is fixedly mounted on the core 1 and connected to the positive electrode tab 11 by welding. One end of the tail body 22 is integrally formed on the plate body 21, and the end of the tail body 22 is continuously arranged with the periphery of the plate body 21. The other end of the tail body 22 is welded and fixed to the cap assembly to realize current conduction.

[0032] like Figure 2 As shown, a narrowing groove 201 is provided at the connection between the disc body 21 and the tail body 22. The portion of the connection between the disc body 21 and the tail body 22 excluding the narrowing groove 201 is the narrowing portion 202, which is... Figure 2 The position between the two dotted lines at the top center. The connection point between the tail body 22 and the disk body 21 is usually the critical path for current transmission from the tail body 22 to the disk body 21. A narrowing groove 201 is opened at this position. When the battery thermal runaway causes an abnormal increase in current, the resistance of the narrowing part 202 is relatively large. Under the same current and time, more heat will be generated at the narrowing part 202, which can more accurately melt under the predetermined current and temperature conditions, thereby cutting off the circuit in time and preventing the battery from further dangerous situations, achieving more precise overcurrent protection for the battery system.

[0033] Meanwhile, when assembling the battery, the positive current collector 2 is bent at the narrowing part 202. The setting of the narrowing part 202 can appropriately weaken the structural strength of the positive current collector 2 at the bending point, thereby making the positive current collector 2 easier to bend and reducing the assembly difficulty of the positive current collector 2.

[0034] The connection position between the tail body 22 and the disc body 21 is relatively regular, making it easy to create grooves using machining, stamping, and other processes. Compared to creating narrowing grooves 201 on the complex curved surfaces or inside the tail body 22 or the disc body 21, machining at the connection position makes it easier to ensure the dimensional accuracy and shape consistency of the narrowing grooves 201, which is beneficial for large-scale production and quality control.

[0035] The narrowing groove 201 at the connection point will not cause additional interference to the assembly of the positive current collector 2 with other battery components. When the positive current collector 2 is assembled with the battery electrodes, casing, and other components, the groove at the connection point will not affect its fitting accuracy and assembly method with other components, ensuring the smooth progress of the entire battery assembly process and improving production efficiency and product yield.

[0036] Since the narrowing groove 201 is located at the connection point between the tail body 22 and the disc body 21, and the positive electrode tab 11 is a full tab, when the disc body 21 is welded and fixed to the positive electrode tab 11, a portion of the positive electrode tab 11 will be exposed within the narrowing groove 201. The end face area of ​​the core 1 is S0, and the area of ​​the positive electrode tab 11 within the narrowing groove 201 is S. 11 ,Right now Figure 3 The area of ​​the positive electrode tab 11 enclosed by the dotted line and the narrowing groove 201 is S. 11 The area of ​​the narrowing section 202 is S 12 .

[0037] In some embodiments, 2%S0≤S 12 ≤3.2%S0, meaning the area of ​​the narrowed portion 202 is 2%, 2.6%, or 3.2% of the end face area of ​​the core 1, etc. If S 12 If S < 2%, the area of ​​the narrowed portion 202 is too small, the structural strength at that location is too low, it is prone to breakage, and metal foreign objects and burrs will be generated, increasing the risk of short circuit and poor K-value in the battery; if S 12 If the area of ​​the narrow section 202 is too large, its melting capacity will decrease. When the battery experiences thermal runaway, the narrow section 202 will not melt in time and will not play an effective protective role, thus reducing the safety performance of the battery.

[0038] Furthermore, 6.5mm is preferred. 2 ≤S 12 ≤10.4mm 2 That is, the area of ​​the narrowed portion 202 is 6.5mm. 2、 8.5mm 2 or 10.4mm 2 wait.

[0039] In some embodiments, 4.6%S0≤S 11≤5.8%S0, meaning the area of ​​the positive electrode tab 11 within the narrowing groove 201 is 4.6%, 5.2%, or 5.8% of the end face area of ​​the core 1, etc. If S 11 If S < 4.6%, the area of ​​the positive electrode tab 11 within the narrowing groove 201 will be too small, increasing the width of the narrowing portion 202 and reducing its fusing capacity, thus failing to provide effective protection and lowering the battery's safety performance. 11 If the area of ​​the positive electrode tab 11 within the narrowing groove 201 is too large, the width of the narrowing part 202 will decrease, the structural strength of the narrowing part 202 will be too low, it will be easy to break, and metal foreign objects and burrs will be generated. The risk of short circuit and poor K value of the battery will increase. At the same time, during normal use of the battery, the excessively narrow narrowing part 202 will heat up for a long time and break, resulting in battery failure and scrap.

[0040] Furthermore, a 15.0mm diameter is preferred. 2 ≤S 11 ≤19.0mm 2 That is, the area of ​​the positive electrode tab 11 located within the narrowing groove 201 is 15.0 mm². 2 17.0mm 2 or 19.0mm 2 wait.

[0041] Furthermore, S0 = 325.4 mm 2 S 12 =8.6mm 2 S 11 =17.0mm 2 This allows the positive electrode current collector 2 to balance structural strength and melting performance, effectively improving the overall performance of the battery.

[0042] like Figure 1 and Figure 2 As shown, the end face radius of core 1 is R0, and the distance between the center point of the end face of core 1 and the narrowing portion 202 is M. 10 The narrowing section 202 has a span of M along the length of the tail section 22. 11 The distance between the narrowing section 202 and the periphery of the core 1 is M. 12 The width of the tail section 22 is W. 30 The width of the narrowing section 202 is W 31 And M 10 +M 11 +M 12 =R0.

[0043] In some embodiments, 42% W 30 ≤W 31 ≤58% W 30That is, the width of the narrowed portion 202 is 42%, 50%, or 58% of the width of the tail section 22, etc. 31 <42% W 30 If the width of the narrow section 202 is too small, its structural strength will be too low, making it prone to breakage, generating metal foreign objects and burrs. This will increase the risk of short circuits and poor K-value in the battery. Simultaneously, during normal battery use, the excessively narrow section 202 will overheat and break, leading to battery failure and disposal. 31 >58% W 30 If the width of the narrow section 202 is too large, the melting capacity of the narrow section 202 will decrease, and it will not play an effective protective role, resulting in a decrease in the safety performance of the battery and an increase in the risk factor.

[0044] Furthermore, it is preferable to have 2.5mm ≤ W 31 ≤3.5mm, meaning the width of the narrowed portion 202 is 2.5mm, 3mm, or 3.5mm, etc.

[0045] Furthermore, W 31 =3mm, W 30 =6mm, W 31 =50%W 30 To balance the structural strength and fusing capacity of the narrowed section 202.

[0046] In some embodiments, 51.8% R0 ≤ M 10 ≤57.7%R0, meaning the distance between the center point of the end face of core 1 and the narrowing section 202 is 52%, 55%, or 57% of the radius of the end face of core 1, etc. If M 10 If R0 is less than 51.8%, the connection between the disc body 21 and the tail body 22 is too close to the center point of the disc body 21, resulting in a decrease in current carrying capacity and weakened strength, making it prone to breakage, generating metal foreign objects and burrs, and increasing the risk of battery short circuit; if M 10 If R0 > 57.7%, the connection between the disk 21 and the tail 22 is too far from the center of the disk 21. The excess disk 21 cannot support more welding wires, nor does it need to handle current, but it will increase the weight of the positive current collector 2, resulting in a decrease in the energy density of the battery and an increase in manufacturing cost.

[0047] In some embodiments, 11.6%R0≤M 11 ≤17.5%R0, meaning the span of the narrowing section 202 along the length of the tail body 22 is 12%, 15%, or 17% of the radius of the end face of the core 1, etc. The two ends of the narrowing section 202 are connected to the disc body 21 and the tail body 22, both of which are made of metal and have strong heat dissipation capabilities. If M... 11If R0 < 11.6%, then the length of the narrowing section 202 is too short. When the narrowing section 202 experiences overcurrent heating, a significant amount of heat will be dissipated by the disc body 21 and the tail body 22, resulting in insufficient overcurrent temperature rise in the narrowing section 202, increasing the fusing time. Furthermore, when the length of the narrowing section 202 is too short, the fusing position will shift, affecting the accuracy of the fusing position and timing. If M 11 If R0 > 17.5%, the length of the narrow section 202 will be too large, the structural strength of the narrow section 202 will be poor, it will be easy to deform and break, generate metal foreign objects, the risk of short circuit and poor K value of the battery will increase, and the safety performance of the battery will be reduced.

[0048] In some embodiments, 27.8% R0 ≤ M 12 ≤33.7%R0, meaning the distance between the narrowed section 202 and the periphery of the core 1 is 28%, 30%, or 33% of the radius of the end face of the core 1, etc. If M 12 If R0 is less than 27.8%, the length of the narrowing section 202 will be too large, resulting in poor structural strength and increased susceptibility to deformation and breakage, leading to the formation of metallic foreign objects. This increases the risk of short circuits and poor K-value in the battery, ultimately reducing its safety performance. If M0 is less than 27.8%, the length of the narrowing section 202 will be too large, weakening its structural strength and making it more prone to deformation and breakage, resulting in the formation of metallic foreign objects. This increases the risk of short circuits and poor K-value in the battery, ultimately reducing its safety performance. 12 If R0 > 33.7%, the length of the narrowing section 202 will be compressed, resulting in poor consistency of the narrowing section 202 and making it impossible to guarantee that it will break at the same location to form an open circuit.

[0049] To improve the stability of the positive current collector 2, it is preferable to set two narrowing slots 201 and arrange the two narrowing slots 201 symmetrically about the center line of the tail body 22.

[0050] like Figure 3 As shown, the narrowing groove 201 includes a first side line 2011, a second side line 2012, and a third side line 2013. The first side line 2011, the second side line 2012, and the third side line 2013 are all inner walls of the narrowing groove 201 and are arranged sequentially. The first side line 2011 is located on the side of the second side line 2012 away from the tail body 22, and the third side line 2013 is located on the side of the second side line 2012 away from the disc body 21. The angle between the first side line 2011 and the second side line 2012 is E, and the angle between the third side line 2013 and the second side line 2012 is F.

[0051] In some embodiments, 72°≤E≤88°, that is, the angle between the first sideline 2011 and the second sideline 2012 is 72°, 80° or 88°, etc. If E<72°, the extra disk 21 does not need to support more bonding wires or handle current, but it will increase the weight of the positive electrode current collector 2, decrease the energy density of the battery, and increase the manufacturing cost. If E>88°, it will affect the solderable area of ​​the bonding wires, resulting in a reduction in the solderable area, an increase in internal resistance, a weakening of the current handling capacity at the bonding wires, and an increase in the current handling temperature at the bonding wires, thus affecting the performance of the battery.

[0052] In some embodiments, 105°≤F≤135°, that is, the angle between the third sideline 2013 and the second sideline 2012 is 105°, 120° or 135°, etc. After the positive electrode current collector 2 is welded, the tail body 22 needs to be bent upward. During the bending process, if F<105°, the tail body 22 is easy to overlap with the plate body 21, causing the narrowing part 202 to fail to play the function of fusing protection; if F>135°, the strength of the tail body 22 becomes lower and it is easy to deform, affecting the reliability of bending and cap welding.

[0053] Furthermore, E = 80° and F = 120°, thus balancing the energy density of the battery with the welding reliability and overcurrent capacity of the positive electrode current collector 2.

[0054] like Figure 1 and Figure 4 As shown, the outer diameter of the disc body 21 is smaller than the area of ​​the end face of the core 1, and the disc body 21 and the end face of the core 1 are concentrically arranged. The distance between the periphery of the core 1 and the periphery of the disc body 21 is L4.

[0055] In some embodiments, 8.6%R0≤L4≤12.6%R0, meaning the distance between the periphery of the core 1 and the periphery of the disc 21 is 9%, 10%, or 12% of the radius of the end face of the core 1. When the core 1 is installed into the battery, the opening of the casing is usually sealed by mechanical sealing with a grooving mechanism. During grooving and mechanical sealing, the casing wall below the groove will deform towards the axial center. If L4<8.6%R0, the disc 21 is too large and close to the outer diameter of the core 1. After the positive electrode current collector 2 is welded to the core 1, the casing wall at this point is likely to contact the edge of the disc 21, increasing the risk of short circuit. If L4>12.6%R0, the diameter of the disc 21 becomes smaller, the weldable area between the disc 21 and the core 1 becomes smaller, the current carrying capacity of the corresponding weld wire weakens, and the temperature rise at the weld wire increases, affecting the performance of the battery.

[0056] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A cylindrical lithium-ion battery, characterized in that: Includes a winding core (1) and a positive current collector (2), wherein, The end face area of ​​the core (1) is S0; The positive current collector (2) includes a disk body (21) and a tail body (22). The disk body (21) is fixedly mounted on the winding core (1). One end of the tail body (22) is integrally formed on the disk body (21) and continuously mounted thereon. A narrowing groove (201) is provided at the connection between the disk body (21) and the tail body (22). The portion of the connection between the disk body (21) and the tail body (22) excluding the narrowing groove (201) is a narrowing portion (202). The area of ​​the narrowing portion (202) is S. 12 Where 2%S0≤S 12 ≤3.2%S0.

2. A cylindrical lithium-ion battery as described in claim 1, characterized in that: The core (1) is provided with a positive electrode tab (11), the positive electrode tab (11) is a full electrode tab, and the disk (21) is connected to the positive electrode tab (11) by welding. The positive electrode tab (11) has an area of ​​S within the narrowing groove (201). 11 Of which, 4.6% S0≤S 11 ≤5.8%S0.

3. A cylindrical lithium-ion battery as described in claim 2, characterized in that: 15.0mm 2 ≤S 11 ≤19.0mm 2 ,6.5mm 2 ≤S 12 ≤10.4mm 2 。 4. A cylindrical lithium-ion battery as described in claim 1, characterized in that: The width of the tail body (22) is W 30 The width of the narrowing portion (202) is W. 31 Of which, 42% W 30 ≤W 31 ≤58%W 30 And 2.5mm≤W 31 ≤3.5mm.

5. A cylindrical lithium-ion battery as described in claim 1, characterized in that: The narrowing groove (201) includes a first side line (2011), a second side line (2012), and a third side line (2013), wherein the first side line (2011), the second side line (2012), and the third side line (2013) are all the inner walls of the narrowing groove (201) and are arranged sequentially and continuously. The first side line (2011) is located on the side of the second side line (2012) away from the tail body (22), and the angle between the first side line (2011) and the second side line (2012) is E, where 72°≤E≤88°.

6. A cylindrical lithium-ion battery as described in claim 5, characterized in that: The third sideline (2013) is located on the side of the second sideline (2012) away from the disk body (21), and the angle between the third sideline (2013) and the second sideline (2012) is F, where 105°≤F≤135°.

7. A cylindrical lithium-ion battery as described in any one of claims 1-6, characterized in that: The end face radius of the core (1) is R0, and the distance between the periphery of the core (1) and the periphery of the disc (21) is L4, wherein 8.6%R0≤L4≤12.6%R0.

8. A cylindrical lithium-ion battery as described in any one of claims 1-6, characterized in that: The end face radius of the core (1) is R0, and the minimum distance between the center point of the end face of the core (1) and the narrowing portion (202) is M. 10 Of which, 51.8% R0≤M 10 ≤57.7%R0.

9. A cylindrical lithium-ion battery as described in claim 8, characterized in that: The narrowing portion (202) has a span of M along the length direction of the tail body (22). 11 Among them, 11.6% R0≤M 11 ≤17.5%R0.

10. A cylindrical lithium-ion battery as described in claim 9, characterized in that: The distance between the narrowing portion (202) and the periphery of the core (1) is M. 12 Of which, 27.8% R0≤M 12 ≤33.7%R0.

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