Cylindrical lithium ion battery and preparation method thereof

Abstract

The invention belongs to the field of new energy batteries, and particularly relates to a cylindrical lithium ion battery and a preparation method thereof.The cylindrical lithium ion battery comprises a shell, a cap, a roll core and a positive collector plate, the shell is of a single-pass structure, a liquid injection hole is formed in the center of the bottom of the shell, a concave table and a nick are arranged between the liquid injection hole and the shell wall, a pole piece is wound to form the roll core, and the positive collector plate is arranged in the shell. A roll core tab forms a welding end face through kneading or flattening, the positive electrode end of the roll core is tightly connected with a positive electrode collector plate through welding, the negative electrode end of the roll core faces the shell to enter the shell and then is tightly connected with the shell through laser penetration welding, the top end of the shell forms a notch platform through a rolling groove, and the collector plate and a cover plate are welded and then sealed through press fit. And after baking, liquid injection and negative pressure formation, welding a liquid injection hole sealing nail to form the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy batteries, and in particular to a cylindrical lithium-ion battery and a preparation method thereof. Background Art

[0002] Cylindrical lithium-ion batteries are widely used in power tools, home energy storage, two-wheeled vehicles, and electric vehicles. However, existing cylindrical batteries produced using a closed-cell formation process, which creates high internal pressure, affects cycle performance, and poses a safety hazard. Furthermore, existing cylindrical batteries require current collector plates for both the positive and negative electrodes, resulting in complex and complex processing steps, leading to high equipment and battery product costs. Summary of the Invention

[0003] The present invention aims to provide a cylindrical lithium-ion battery and a preparation method thereof, so as to solve the problems existing in the prior art such as high internal pressure of the battery caused by the inability to release internal gas of the grooved battery and high processing costs caused by the large number of structural parts.

[0004] The present invention provides a cylindrical lithium-ion battery comprising a shell, a cap, a winding core, and a current collecting plate. The shell is a single-pass structure, with a liquid injection hole provided at the center of the bottom of the shell, and a concave platform and a notch provided between the liquid injection hole and the shell wall. The cap is a combined cap, provided with a CID and a VENT; The winding core is provided with tabs at both ends, which are flattened and patted to form welding end faces; The collecting disc includes a collecting disc body, a cap welding area and an extension handle. The collecting disc body is used to connect the welding end face of the winding core, the cap welding area is used to connect the cap, and the extension handle is used to connect the winding core and the cap, and has assembly and electronic conduction functions.

[0005] Preferably, the shell material is one of low carbon steel, nickel-plated steel and stainless steel.

[0006] Preferably, the diameter of the injection hole is 1-6 mm.

[0007] Preferably, the concave platform is used for laser penetration welding and is one of a ray-shaped and annular shape.

[0008] Preferably, the notch is annular, has a notch depth of 0.2-0.7 mm, and a notch diameter of 7-50 mm.

[0009] Preferably, the rupture pressures of the CID, VENT, notch and shell are 1.0-2.0 MPa, 2.0-3.0 MPa, 3.0-4.0 MPa and 4.0-9.0 MPa, respectively.

[0010] Preferably, the collecting plate is made of aluminum or aluminum alloy.

[0011] Preferably, the collecting disc body and the extension handle are both provided with reinforcing ribs, and the collecting disc body is also provided with a liquid guide hole and a welding recess.

[0012] The present invention also provides a method for preparing a cylindrical lithium-ion battery, comprising the following steps: S1: The pole piece is wound to form a core, and the pole ear of the core is flattened or flattened to form a welding end face; S2: One end of the core is tightly connected to the collecting plate by welding, and the other end of the core is inserted into the shell and then tightly connected to the shell by laser penetration welding; S3: The top of the shell is grooved to form a notch platform, and the collecting plate and the cover plate are welded and then pressed and sealed; S4: After baking, liquid injection and negative pressure formation, the sealing pins of the liquid injection hole are welded to form a battery.

[0013] Preferably, after the winding core is flattened or patted, the height of the exposed diaphragm of the tab is 0.5~3mm, and the parameters of the laser welding process are: laser power 100W-1000W, welding speed 100mm / s-800mm / s, defocus amount 0mm-2mm. In order to ensure the baking efficiency of the battery, the battery injection hole is facing upward, and a contoured jacket is used to heat the battery side wall. The injection can be a single injection or multiple injections.

[0014] The beneficial effects of the present invention are: 1. There is no current collecting plate between the bottom of the shell and the winding core tab. The tab is directly welded to the shell, which reduces the number of structural parts, reduces material and production costs, and improves production efficiency. 2. The winding core is directly connected to the shell, reducing the connection interface between the collector plate and the tab / shell, reducing the contact internal resistance, improving the heat dissipation performance, and achieving high-power charging and discharging; 3. A liquid injection port is set at the bottom of the shell to realize the negative pressure formation of the groove-sealed battery, reduce the internal pressure of the battery and improve the cycle performance; 4. A liquid injection port is set at the bottom of the shell to realize the helium leakage detection of the rolling groove sealed battery, effectively preventing the leakage of the battery due to rolling groove and sealing nail welding; 5. Explosion-proof notches are set on the bottom of the shell, and CID and VENT are set on the top of the cover, which can achieve three-level pressure relief and directional energy release, which can effectively prevent the battery from side cracking and explosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A flow chart for preparing the battery of the present invention; Figure 2 Schematic diagram of a cross-section of a battery according to the present invention; Figure 3 is a schematic diagram of a battery of the present invention; Figure 4This is a schematic diagram of the bottom of the battery of the present invention; Figure 5 It is a schematic diagram of the cap structure of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be further explained below with reference to specific embodiments. Example

[0017] refer to Figure 1-5 In this embodiment, a cylindrical lithium-ion battery is proposed, including a shell, a cap, a winding core and a current collecting plate. The shell is a single-pass structure, a liquid injection hole is provided at the center of the bottom of the shell, and a concave platform and a notch are provided between the liquid injection hole and the shell wall; The cap is a combined cap, provided with a CID and a VENT; The winding core is provided with tabs at both ends, which are flattened and patted to form welding end faces; The collecting disc includes a collecting disc body, a cap welding area and an extension handle. The collecting disc body is used to connect the welding end face of the winding core, the cap welding area is used to connect the cap, and the extension handle is used to connect the winding core and the cap, and has assembly and electronic conduction functions.

[0018] In this embodiment, the shell material is one of low carbon steel, nickel-plated steel, and stainless steel, the diameter of the injection hole is 1~6 mm, the recess is used for laser penetration welding, and is one of radial and annular, the notch is annular, the notch depth is 0.2~0.7 mm, and the notch diameter is 7~50 mm. The rupture pressures of the CID, VENT, notch and shell are 1.0~2.0 MPa, 2.0~3.0 MPa, 3.0~4.0 MPa and 4.0~9.0 MPa respectively. The material of the collecting plate is one of aluminum and aluminum alloy. The collecting plate body and the extension handle are provided with reinforcing ribs, and the collecting plate body is also provided with a liquid guide hole and a welding recess.

[0019] A method for preparing a cylindrical lithium-ion battery comprises the following steps: S1: The pole piece is wound to form a core, and the pole ear of the core is flattened or flattened to form a welding end face; S2: One end of the core is tightly connected to the collecting plate by welding, and the other end of the core is inserted into the shell and then tightly connected to the shell by laser penetration welding; S3: The top of the shell is grooved to form a notch platform, and the collecting plate and the cover plate are welded and then pressed and sealed; S4: After baking, liquid injection and negative pressure formation, the sealing pins of the liquid injection hole are welded to form a battery.

[0020] After the winding core is flattened or patted, the height of the exposed diaphragm of the tab is 0.5~3mm. The parameters of the laser welding process are: laser power 100W-1000W, welding speed 100mm / s-800mm / s, defocus amount 0mm-2mm. In order to ensure the baking efficiency of the battery, the battery injection hole is facing upward, and a contoured jacket is used to heat the battery side wall. The injection can be a single injection or multiple injections.

[0021] There is no collecting plate between the bottom of the shell and the winding core tab, and the tab is directly welded to the shell, which reduces the number of structural parts, reduces material and production costs, and improves production efficiency. The winding core is directly connected to the shell, reducing the connection interface between the collecting plate and the tab / shell, reducing the contact internal resistance, improving the heat dissipation performance, and achieving high-power charging and discharging. A liquid injection port is set at the bottom of the shell to realize the negative pressure formation of the grooved sealed battery, reduce the internal air pressure of the battery, and improve the cycle performance. A liquid injection port is set at the bottom of the shell to realize helium leakage detection of the grooved sealed battery, effectively preventing the leakage of the battery due to the groove and sealing nail welding. An explosion-proof notch is set at the bottom of the shell, and a CID and VENT are set on the top of the cover plate, which can achieve three-level pressure relief and directional energy release, which can effectively prevent the battery from side cracking and explosion. The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A cylindrical lithium-ion battery comprising a housing, a cap, a winding core and a current collecting plate, characterized in that: The shell is a single-pass structure, with a liquid injection hole at the center of the bottom of the shell, and a concave platform and a notch between the liquid injection hole and the shell wall; The cap is a combined cap, provided with a CID and a VENT; The rupture pressures of the CID, VENT, notch, and housing satisfy the following relationship: CID < VENT < notch < housing; The winding core is provided with tabs at both ends, which are flattened and patted to form welding end faces; The collecting disc includes a collecting disc body, a cap welding area and an extension handle. The collecting disc body is used to connect the welding end face of the winding core, the cap welding area is used to connect the cap, and the extension handle is used to connect the winding core and the cap, and has assembly and electronic conduction functions.

2. A cylindrical lithium-ion battery according to claim 1, characterized in that: The shell is made of one of low carbon steel, nickel-plated steel and stainless steel.

3. A cylindrical lithium-ion battery according to claim 1, characterized in that: The diameter of the injection hole is 1-6 mm.

4. The cylindrical lithium-ion battery according to claim 1, characterized in that: The concave platform is used for laser penetration welding and is in one of a ray shape and a ring shape.

5. The cylindrical lithium-ion battery according to claim 1, characterized in that: The notch is annular, has a notch depth of 0.2-0.7 mm, and a notch diameter of 7-50 mm.

6. The cylindrical lithium-ion battery according to claim 1, characterized in that: The bursting pressures of the CID, VENT, explosion-proof notch and shell are 1.0-2.0 MPa, 2.0-3.0 MPa, 3.0-4.0 MPa and 4.0-9.0 MPa respectively.

7. The cylindrical lithium-ion battery according to claim 1, characterized in that: The material of the collecting plate is one of aluminum and aluminum alloy.

8. The cylindrical lithium-ion battery according to claim 1, characterized in that: The collecting disc body and the extension handle are both provided with reinforcing ribs, and the collecting disc body is also provided with a liquid guide hole and a welding recess.

9. A method for preparing a cylindrical lithium-ion battery, characterized in that: The following steps are involved: S1: The pole piece is wound to form a core, and the pole ear of the core is flattened or flattened to form a welding end face; S2: One end of the core is tightly connected to the collecting plate by welding, and the other end of the core is inserted into the shell and then tightly connected to the shell by laser penetration welding; S3: The top of the shell is grooved to form a notch platform, and the collecting plate and the cover plate are welded and then pressed and sealed; S4: After baking, liquid injection and negative pressure formation, the sealing pins of the liquid injection hole are welded to form a battery.

10. The method for preparing a cylindrical lithium-ion battery according to claim 8, characterized in that: After the winding core is flattened or patted, the height of the exposed diaphragm of the tab is 0.5~3mm. The parameters of the laser welding process are: laser power 100W-1000W, welding speed 100mm / s-800mm / s, defocus amount 0mm-2mm. In order to ensure the baking efficiency of the battery, the battery injection hole is facing upward, and a contoured jacket is used to heat the battery side wall. The injection can be a single injection or multiple injections.

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