阅读说明：本技术 一种动力电池及其封口方法 (Power battery and sealing method thereof ) 是由 李�杰 王文伟 曾兵 王智辉 于 2020-12-22 设计创作，主要内容包括：一种动力电池及其封口方法,其中,封口方法包括：将金属板坯和动力电池的顶盖平行间隔放置,使顶盖上的注液孔位于金属板坯的覆盖范围内；采用电磁脉冲焊的方式使金属板坯与顶盖结合为一体,以封闭注液孔。由于采用电磁脉冲焊的方式,可使得金属板坯能够在电磁感应作用下以极大地速度冲撞顶盖,在金属板坯与顶盖高速碰撞接触后,将两者结合为一体,从而通过快速完成对金属板坯的焊接作业来实现对注液孔的封口处理,相较于激光焊接方式,由于封口焊接过程中不受热量影响,不会产生小孔或焊缝爆点,可获得高质量封口焊接的效果。(A power battery and a sealing method thereof are provided, wherein the sealing method comprises the following steps: placing the metal plate blank and a top cover of the power battery in parallel at intervals, and enabling a liquid injection hole in the top cover to be positioned in the coverage range of the metal plate blank; the metal plate blank and the top cover are combined into a whole by adopting an electromagnetic pulse welding mode so as to seal the liquid injection hole. Due to the adoption of the mode of electromagnetic pulse welding, the metal plate blank can collide with the top cover at a very high speed under the action of electromagnetic induction, and the metal plate blank and the top cover are combined into a whole after being collided and contacted at a high speed, so that the sealing treatment of the liquid injection hole is realized by quickly finishing the welding operation on the metal plate blank.)

1. A sealing method of a power battery is characterized by comprising the following steps:

placing the metal plate blank and a top cover of the power battery in parallel at intervals, and enabling a liquid injection hole in the top cover to be positioned in the coverage range of the metal plate blank;

and combining the metal plate blank and the top cover into a whole by adopting an electromagnetic pulse welding mode so as to seal the liquid injection hole.

2. The method of sealing as claimed in claim 1, wherein said step of positioning the metal blank and the top cover of the power cell in spaced parallel relation and positioning the pour hole in the top cover within the footprint of the metal blank comprises:

accommodating the main body of the sealing nail in the liquid injection hole, and overlapping the top end edge of the sealing nail on the groove surface of the accommodating sinking groove communicated with the liquid injection hole, so that an annular gap is formed between the top end edge of the sealing nail and the groove wall of the accommodating sinking groove;

and overlapping the metal plate blank on the outer surface of the top cover and covering the accommodating sinking groove, so that a gap is formed between the metal plate blank and the groove surface of the accommodating sinking groove.

3. The method of sealing a mouth as claimed in claim 2, wherein said step of using electromagnetic pulse welding to integrate said metal sheet blank with said top cover to close said pour hole comprises:

and the metal plate blank quickly impacts the top cover at the annular gap under the action of electromagnetic induction to realize the combination of the metal plate blank and the top cover so as to finish the sealing of the liquid injection hole and the blanking of the metal plate blank.

4. The method of claim 3, wherein said step of rapidly impacting said metal blank against said top cover at said annular gap under electromagnetic induction to join said metal blank to said top cover to complete the sealing of said pour hole and the punching of said metal blank comprises:

placing a discharge coil on one side of the metal plate blank, which is far away from the top cover, so that the discharge coil is over against the metal plate blank;

and switching on a capacitor to discharge the discharge coil, so that the metal plate blank quickly impacts the top cover under the action of electromagnetic induction.

5. A method of closing a mouth as claimed in claim 2, wherein the depth of said receiving recess is equal to or greater than the thickness of the metal slab.

6. The method of sealing as claimed in claim 1, wherein said step of positioning the metal blank and the top cover of the power cell in spaced parallel relation and positioning the pour hole in the top cover within the footprint of the metal blank comprises:

accommodating the main body of the sealing nail in the liquid injection hole, and enabling the outer end edge of the sealing nail to be lapped on the outer surface of the top cover or enabling the outer end face of the sealing nail to protrude out of the outer surface of the top cover;

and overlapping the metal plate blank on the outer end face of the sealing nail and covering the sealing nail so that a space exists between the metal plate blank and the outer surface of the top cover.

7. The method of claim 6, wherein the step of using electromagnetic pulse welding to integrate the metal plate blank with the top cover to close the pour hole comprises:

and the metal plate blank quickly impacts the top cover in the peripheral area of the sealing nail under the action of electromagnetic induction to realize the combination of the metal plate blank and the top cover so as to finish the sealing of the liquid injection hole.

8. The method of claim 7, wherein the step of rapidly striking the metal blank against the top cap at the peripheral region of the sealing nail by electromagnetic induction to join the metal blank to the top cap to complete the sealing of the pour hole comprises:

placing a discharge coil on one side of the metal plate blank, which is far away from the top cover, so that the discharge coil is over against the metal plate blank;

and switching on a capacitor to discharge the discharge coil, so that the metal plate blank quickly impacts the top cover under the action of electromagnetic induction.

9. A power battery, comprising a top cover and a liquid injection hole arranged on the top cover, and is characterized by further comprising a sealing member, wherein the sealing member is integrated with the top cover through the sealing method of the power battery as claimed in any one of claims 1 to 8.

Technical Field

The invention relates to the field of power battery production, in particular to a power battery and a sealing method thereof.

Background

In the production and manufacturing process of the power battery, after the welding process of the battery shell is completed, electrolyte needs to be injected into the battery shell through a liquid injection hole formed in a top cover of the battery shell, and then the liquid injection hole is plugged by a sealing rubber nail, so that the sealing treatment of the liquid injection hole is realized by the sealing rubber nail; as the last process of power battery production and manufacture, the sealing process of the liquid injection hole is of great importance, and if the liquid injection hole cannot be sealed, the power battery can be directly scrapped.

At present, the sealing treatment is carried out on the liquid injection hole by adopting a laser welding mode in the industry, namely: after the sealing rubber nail is plugged and blocked on the liquid injection hole, the sealing rubber nail is welded on the top cover in a fusion welding mode by utilizing laser beams; the method has the problems that the liquid injection hole cannot be sealed by the sealing rubber nail, and the like, and product defects are easily caused.

Disclosure of Invention

The invention mainly solves the technical problem of a sealing method of a power battery and the power battery applying the sealing method, so as to improve the sealing quality of the power battery.

According to a first aspect, in one embodiment, a method for sealing a power battery is provided, which includes the following steps:

placing the metal plate blank and a top cover of the power battery in parallel at intervals, and enabling a liquid injection hole in the top cover to be positioned in the coverage range of the metal plate blank;

and combining the metal plate blank and the top cover into a whole by adopting an electromagnetic pulse welding mode so as to seal the liquid injection hole.

In one embodiment, the step of placing the metal plate blank and the top cover of the power battery in parallel and at intervals, and enabling the liquid injection hole in the top cover to be located in the coverage range of the metal plate blank comprises the following steps:

accommodating the main body of the sealing nail in the liquid injection hole, and overlapping the top end edge of the sealing nail on the groove surface of the accommodating sinking groove communicated with the liquid injection hole, so that an annular gap is formed between the top end edge of the sealing nail and the groove wall of the accommodating sinking groove;

and overlapping the metal plate blank on the outer surface of the top cover and covering the accommodating sinking groove, so that a gap is formed between the metal plate blank and the groove surface of the accommodating sinking groove.

In one embodiment, the step of combining the metal plate blank and the top cover into a whole by adopting an electromagnetic pulse welding mode to close the liquid injection hole comprises the following steps:

and the metal plate blank quickly impacts the top cover at the annular gap under the action of electromagnetic induction to realize the combination of the metal plate blank and the top cover so as to finish the sealing of the liquid injection hole and the blanking of the metal plate blank.

In one embodiment, the step of making the metal plate blank quickly impact the top cover at the annular gap under the action of electromagnetic induction to realize the combination of the metal plate blank and the top cover so as to complete the sealing of the liquid injection hole and the blanking of the metal plate blank includes:

placing a discharge coil on one side of the metal plate blank, which is far away from the top cover, so that the discharge coil is over against the metal plate blank;

and switching on a capacitor to discharge the discharge coil, so that the metal plate blank quickly impacts the top cover under the action of electromagnetic induction.

In one embodiment, the depth of the accommodating sinking groove is greater than or equal to the thickness of the metal plate blank.

In one embodiment, the step of placing the metal plate blank and the top cover of the power battery in parallel and at intervals, and enabling the liquid injection hole in the top cover to be located in the coverage range of the metal plate blank comprises the following steps:

accommodating the main body of the sealing nail in the liquid injection hole, and enabling the outer end edge of the sealing nail to be lapped on the outer surface of the top cover or enabling the outer end face of the sealing nail to protrude out of the outer surface of the top cover;

and overlapping the metal plate blank on the outer end face of the sealing nail and covering the sealing nail so that a space exists between the metal plate blank and the outer surface of the top cover.

In one embodiment, the step of combining the metal plate blank and the top cover into a whole by adopting an electromagnetic pulse welding mode to close the liquid injection hole comprises the following steps:

and the metal plate blank quickly impacts the top cover in the peripheral area of the sealing nail under the action of electromagnetic induction to realize the combination of the metal plate blank and the top cover so as to finish the sealing of the liquid injection hole.

In one embodiment, the step of enabling the metal plate blank to quickly impact the top cover on the peripheral area of the sealing nail under the action of electromagnetic induction to realize the combination of the metal plate blank and the top cover so as to complete the sealing of the liquid injection hole includes:

placing a discharge coil on one side of the metal plate blank, which is far away from the top cover, so that the discharge coil is over against the metal plate blank;

and switching on a capacitor to discharge the discharge coil, so that the metal plate blank quickly impacts the top cover under the action of electromagnetic induction.

According to a second aspect, an embodiment provides a power battery, which includes a top cover, a liquid injection hole provided on the top cover, and a sealing member, wherein the sealing member is integrated with the top cover by the sealing method of the power battery of the first aspect.

The method for sealing the power battery according to the embodiment comprises the following steps: placing the metal plate blank and a top cover of the power battery in parallel at intervals, and enabling a liquid injection hole in the top cover to be positioned in the coverage range of the metal plate blank; the metal plate blank and the top cover are combined into a whole by adopting an electromagnetic pulse welding mode so as to seal the liquid injection hole. Due to the adoption of the mode of electromagnetic pulse welding, the metal plate blank can collide with the top cover at a very high speed under the action of electromagnetic induction, and the metal plate blank and the top cover are combined into a whole after being collided and contacted at a high speed, so that the sealing treatment of the liquid injection hole is realized by quickly finishing the welding operation on the metal plate blank.

Drawings

Fig. 1 is a flowchart of a sealing method of a power battery according to an embodiment.

Fig. 2 is an exploded view of the power battery according to an embodiment.

Fig. 3 is a schematic structural diagram of a power battery in a pre-assembly state according to an embodiment.

Fig. 4 is a schematic structural state diagram of the power battery of an embodiment after the sealing process is completed.

Fig. 5 is a flowchart of a sealing method of a power battery according to another embodiment.

Fig. 6 is a schematic structural diagram of another embodiment of a power battery in a pre-assembly state.

Fig. 7 is a schematic structural state diagram of a power battery of another embodiment after finishing a sealing process.

Fig. 8 is a circuit diagram of a pulse electromagnetic device used in a sealing method of a power battery according to an embodiment.

In the figure:

10. a top cover; 20. a liquid injection hole; 30. sealing the nail; 40. a metal slab; 50. a containing sink groove; 60. a discharge coil; 70. a capacitor; 80. a switch; 90. a power source.

Detailed Description

The present invention will be described in further detail with reference to the following detailed description and accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.

Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.

The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings).

When the power battery is manufactured, the sealing nail is required to be used for sealing the liquid injection hole in the top cover of the power battery shell, so that the electrolyte can be prevented from splashing or overflowing from the power battery shell in the process of carrying the power battery (such as the process of carrying the power battery to a welding station) through the sealing nail, and the sealing treatment of the liquid injection hole can be finally realized through the sealing nail. At present, the laser welding sealing treatment mode adopted in the industry is mainly to directly weld a sealing nail on a top cover of a shell of a power battery so as to finish the sealing treatment of a liquid injection hole, and because part of electrolyte is easily remained at a part, used for accommodating the sealing nail and communicated with the liquid injection hole, on the top cover in the electrolyte injection and power battery carrying processes, the electrolyte and crystals thereof can be formed after standing for a long time; therefore, when laser welding operation is carried out, laser beams are easy to splash and form small holes due to residual electrolyte and crystals thereof, or welding seam explosion points are formed at the joint of the head and the tail of the welding seam due to overhigh air pressure of a closed cavity formed between the sealing nail and the liquid injection hole, so that the sealing nail cannot be closed, and product defects are caused. Meanwhile, before laser welding operation, plastic auxiliary materials are separately manufactured into a sealing nail sample piece in modes of blanking or laser cutting and the like according to the size specification of the liquid injection hole, so that the sealing nail and the liquid injection hole can be accurately matched; but also cleaning impurities at the welding position and planning a welding track; therefore, the complexity of the sealing treatment process is increased to a certain extent, the production process and the production cost of the power battery are increased, and the production efficiency is reduced.

The method for sealing the power battery comprises the steps that firstly, a metal plate blank is placed on the outer surface side of a top cover of the power battery, a liquid injection hole in the top cover is located in the coverage range of the metal plate blank (namely the coverage area of the metal plate blank is larger than the area of a port of the liquid injection hole in the top cover), then the metal plate blank and the top cover are welded into a whole in a combined mode through electromagnetic pulse welding, and sealing treatment of the liquid injection hole is achieved; compared with a laser welding mode, the seal welding process is not influenced by heat, small holes or weld joint explosion points cannot be generated, and a high-quality seal welding effect can be obtained; and the welding forming speed of the electromagnetic pulse welding is high, auxiliary materials are not needed to be matched, the sealing welding efficiency is favorably improved, and favorable conditions are created for clean and full-automatic production and manufacture of the power battery. Meanwhile, through structural selection design of the top cover and the liquid injection hole, optimization design of the arrangement mode of the metal plate blank and the like, the metal plate blank can be synchronously blanked while welding of the metal plate blank is completed, blanking of sealing welding and sealing pieces is completed in one step, welding efficiency can be effectively improved, production procedures can be reduced, and the like.

The first embodiment is as follows:

referring to fig. 2, fig. 3, fig. 4, fig. 6 and fig. 7, the power battery provided in this embodiment includes a top cover 10 as a part of a housing of the power battery, a liquid injection hole 20 for providing a structural passage for injecting an electrolyte into the housing of the power battery, and a sealing member for sealing the liquid injection hole 20; wherein the seal comprises a seal pin 30 and a metal slab 40; the following are described separately.

The pouring hole 20 is formed in the top lid 10. referring to FIGS. 6 and 7, the pouring hole 20 may be formed in a single cylindrical through-hole structure so that the pouring hole 20 is directly received in the main body of the sealing nail 30, thereby sealing the pouring hole 20 with the sealing nail 30, and at the same time, the outer end surface of the sealing nail 30 protrudes from the outer surface of the top lid 10 or the outer end edge (i.e., flange) of the sealing nail 30 is overlapped on the outer surface of the top lid 10.

In another embodiment, referring to fig. 2, fig. 3 and fig. 4, the final form of the liquid injection hole 20 may also adopt a reducing type cylindrical through hole structure, that is: the outer surface side of the top cover 10 is provided with a containing sunken groove 50, the containing sunken groove 50 is communicated with the liquid injection hole 20, the inner diameter of the containing sunken groove 50 is larger than the aperture of the liquid injection hole 20 and larger than the diameter of the top surface of the sealing nail 30, the main body part of the sealing nail 30 is contained by the liquid injection hole 20, the top surface edge of the sealing nail 30 is contained by the containing sunken groove 50, the top surface edge of the sealing nail 30 can be lapped on the groove surface of the containing sunken groove 50, an annular gap (not marked in the figure) distributed around the sealing nail 30 can be formed between the top surface edge of the sealing nail 30 and the groove wall of the containing sunken groove 50, and a structural space can be provided for the combination of the metal plate blank 40 and the groove surface (which is equivalent to the top cover 10) of the containing sunken groove 50 by the annular gap.

The metal plate blank 40 is made of a metal material or a high-conductivity material which is the same as the top cover 10 in material, and is mainly used for being combined with the top cover 10 into a whole (namely, welded into a whole) under the action of electromagnetic induction so as to play a role in sealing an assembly forming area of the sealing nail 30 and the liquid injection hole 20 or sealing the liquid injection hole 20, and the covering area of the metal plate blank 40 is larger than the area of the outer end face of the sealing nail 30 or the area of a notch of the accommodating sunken groove 50, so that the metal plate blank 40 can completely cover the sealing nail 30 or accommodate the sunken groove 50; the coverage area is understood to mean the surface area of the metal blank 40, i.e. the length and width of the metal blank 40 when it is a rectangular plate-shaped structure, or the diameter or radius of the metal blank 40 when it is a circular plate-shaped structure. Referring to fig. 6 and 7, in the embodiment where the outer end surface of the seal nail 30 protrudes from the outer surface of the top cap 10 or the outer end edge of the seal nail 30 overlaps the outer surface of the top cap 10, the outer end surface of the seal nail 30 is located within the coverage of the metal plate blank 40, and the outer peripheral region of the metal plate blank 40 located at the outer end of the seal nail 30 is integrated with the outer surface of the top cap 10; referring to fig. 2, 3 and 4, in the embodiment where the receiving recess 50 exists, the outer end surface of the seal nail 30 is located within the coverage of the metal plate blank 40, and the outer peripheral area of the metal plate blank 40 located at the outer end of the seal nail 30 is integrated with the recess surface of the receiving recess 50 at the annular gap.

Based on this, the liquid filling hole 20 is sealed for the first time by the sealing nail 30, and the liquid filling hole 20 and the sealing nail 30 are sealed for the second time by the combination of the metal plate blank 40 and the top cover 10, so that the sealing quality of the liquid filling hole 20 can be effectively improved.

Example two:

referring to fig. 1, the sealing method for a power battery according to the present embodiment is mainly used for welding and combining a metal plate blank 40 and a top cover 10 into a whole to synchronously implement a sealing process for a liquid injection hole 20 and a blanking process for the metal plate blank 40, and the sealing method includes steps 101 to 104; the following are described separately.

In step 101, a containing sink groove 50 is formed on the outer surface side of the top cover 10, the containing sink groove 50 is distributed around the liquid injection hole 20, and the containing sink groove 50 is coaxially communicated with the liquid injection hole 20.

Referring to fig. 2, 3 and 4, the inner diameter of the receiving sink 50 is larger than the outer end diameter of the liquid injection hole 20, and this step can be selected according to the shape of the top lid 10, for example, before the existing top lid is sealed, the structure of the liquid injection hole needs to be temporarily modified, so as to form the structural form of the receiving sink 50 and the liquid injection hole 20, that is: this step needs to be performed; if the top cover is provided with the containing sink 50 and the liquid pouring hole 20, the step can be omitted.

And 102, accommodating the main body of the sealing nail 30 in the liquid injection hole 20, overlapping the outer end edge of the sealing nail 30 on the groove surface of the accommodating sunken groove 50, and enabling an annular gap to exist between the outer end edge of the sealing nail 30 and the groove wall of the accommodating sunken groove 50.

Referring to FIGS. 2, 3 and 4, after the main body of the sealing pin 30 is placed in the pour hole 20 to close the pour hole 20, the outer end edge of the sealing pin 30 can be lapped on the groove surface of the receiving sunken groove 50 by using the structural characteristic that the inner diameter d1 of the receiving sunken groove 50 is larger than the diameter d2 of the outer end surface of the sealing pin 30, and an annular gap with a certain distance is formed between the outer end peripheral wall of the sealing pin 30 and the groove wall of the receiving sunken groove 50. When the sealing nail 30 is selected or manufactured, the main body part of the sealing nail 30 is only required to be accurately matched with the liquid injection hole 20, and the size of the outer end of the sealing nail 30 is between the aperture of the liquid injection hole 20 and the inner diameter d1 of the accommodating sunken groove 50; or based on the liquid injection hole site on the existing power battery and the sealing rubber nail matched with the liquid injection hole site, flaring processing is carried out on the outer end side of the liquid injection hole site on the top cover of the power battery, and a condition is created for arranging the sealing rubber nail by adopting the assembly mode by utilizing the formed accommodating sinking groove 50.

Step 103, overlapping the metal plate blank 40 on the outer surface of the top cover 10 and covering the accommodating sunken groove 50, so that a gap exists between the metal plate blank 40 and the groove surface of the accommodating sunken groove 50.

Referring to fig. 2, 3 and 4, when selecting the specification and size of the metal slab 40, the metal slab 40 with a surface area larger than the area of the notch of the receiving recess 50 is selected, and the metal slab 40 is stacked on the outer surface of the top cover 10 to cover the surface area of the notch of the receiving recess 50, so that the sealing nail 30 and the pour hole 20 can be completely covered, and a certain interval can be formed between the metal slab 40 and the notch of the receiving recess 50, so that the welded area of the metal slab 40 and the top cover 10 is parallel and spaced. The metal plate blank 40 is made of a metal material or a highly conductive material which is the same as the material of the top cover 10.

And 104, combining the metal plate blank 40 and the top cover 10 into a whole by adopting an electromagnetic pulse welding mode to finish the sealing of the liquid injection hole 20 and the blanking of the metal plate blank 40.

Referring to fig. 3 and 8, an electromagnetic pulse welding apparatus is constructed using a discharge coil 60, a capacitor 70, a switch 80, a power supply 90, and associated charge and discharge management circuitry; wherein, the power supply 90 can adopt 220V alternating current power supply, one end of the discharge coil 60 is connected with one end of the switch 80 through the power supply 90, the other end of the discharge coil 60 is directly connected with the switch 80, and the capacitor 70 is connected with the power supply 90 in parallel through the charge-discharge management circuit; meanwhile, the discharge coil 60 is arranged on one side of the metal plate blank 40 far away from the top cover 10, so that the discharge coil 60 is over against the metal plate blank 40, and the discharge coil 60 and the metal plate blank 40 are oppositely distributed up and down.

Before the switch 80 is closed (or turned on), the capacitor 70 is charged to saturation by the power source 90, and then the switch 80 is closed (or turned on) so that the capacitor 70 instantaneously discharges the discharge coil 60, thereby forming a varying pulse excitation current in the discharge coil 60, and then forming a strong magnetic field around the discharge coil 60, which generates an eddy current (i.e., an induced current in opposite directions) on the surface side of the discharge coil 60 close to the metal slab 40 according to the law of electromagnetic induction, thereby forming another pulse magnetic field, while the two electromagnetic fields in opposite directions generate an electromagnetic repulsion force (i.e., an electromagnetic force), which drives the portion of the metal slab 40 located in the notch region of the accommodating slot 50 to move rapidly downward, and during the movement of the portion, an isolation effect and an upward stress are generated on the portion of the metal slab 40 due to the presence of the sealing pin 30, the part of the metal plate blank 40 can be enabled to impact the groove surface of the accommodating sunken groove 50 at a high speed in the annular gap area (namely, the part of the metal plate blank 40 corresponding to the local area of the top cover 10 is impacted at a high speed), so that the part of the metal plate blank 40 and the groove surface of the accommodating sunken groove 50 can be welded and combined into a whole after being in high-speed impact contact.

Meanwhile, since the portion of the metal slab 40 located in the outer peripheral area of the notch of the receiving recess 50 cannot move due to the overlapping contact relationship with the top lid 10 (i.e., no gap exists), the metal slab 40 is cut and punched into two portions (i.e., the portion located in the outer peripheral area of the notch of the receiving recess 50 and the portion located in the receiving recess 50 and welded to the notch surface of the receiving recess 50) at one time by the combined action of the height difference between the notch surface of the receiving recess 50 and the outer surface of the top lid 10 (or the approximately stepped structure formed therebetween), the downward force generated by the electromagnetic force on the metal slab 40, the upward stress applied to the top lid 10, and other factors.

Firstly, the power battery is sealed by adopting a pulse electromagnetic welding method, the power battery can be free from the influence of heat or hot areas, the metal plate blank 40 and the top cover 10 are welded and combined in high quality by utilizing the high-speed collision effect between the two, not only small holes or weld joint explosion points are not generated after welding, but also the welding quality can be effectively ensured, the welding track does not need to be planned or continuous welding operation is carried out according to the welding track, the welding and combining forming speed is high, the welding efficiency is high, and the cleaning and automatic production and manufacturing of the power battery are easy to realize.

Secondly, by utilizing the height difference between the groove surface of the accommodating sink groove 50 and the outer surface of the top cover 10 and the stress action of the sealing nail 30 and the top cover 10 on the metal plate blank 40, the metal plate blank 40 can be welded, meanwhile, the shearing and blanking processing on the metal plate blank 40 is completed, the one-step forming of welding and blanking is realized, the sealing nail 30 and the metal plate blank 40 which are accurately matched with the specification and the size of the liquid injection hole 20 do not need to be manufactured separately, the whole production process of the power battery is favorably reduced, and favorable conditions are created for reducing the production cost and improving the production efficiency.

Thirdly, when the metal plate blank 40 and the top cover 10 are in high-speed collision contact (for example, when the metal plate blank and the top cover are collided at a speed of 300-500 mm/s by using a pulse electromagnetic field), a metal jet flow is generated at a collision point, so that impurities at a part (for example, an annular gap) to be welded and combined between the metal plate blank and the top cover can be cleaned completely by using the metal jet flow and are in close contact with each other, thereby realizing welding and combination, and the impurity cleaning of the welding part is not required in advance, so that the production process of the power battery can be further reduced.

In one embodiment, referring to fig. 3, the depth h of the accommodating sunken groove 50 is greater than or equal to the thickness t of the metal plate blank 40, so that structural conditions can be created for shearing and blanking the metal plate blank 40, and the welded part of the metal plate blank 40 and the top cover 10 can be completely located in the accommodating sunken groove 50, thereby realizing hidden protection of the welding point; in another embodiment, the depth h of the receiving recess 50 is preferably equal to or greater than the sum of the thickness of the metal blank 40 and the thickness of the outer end of the seal nail 30 (i.e., the portion of the structure located in the receiving recess 50), so that the outer surface of the metal blank 40 is flush with the outer surface of the top cover 10 after the welding of the metal blank 40 to the top cover 10 is completed, thereby minimizing the influence on the appearance of the top cover 10.

Example three:

referring to fig. 5, a difference between the sealing method of the power battery provided in the embodiment and the second embodiment is that: the sealing method of the embodiment adopts another different structural arrangement relationship among the sealing nail 30, the metal plate blank 40 and the top cover 10 (namely, the accommodating sinking groove 50 is omitted), and the sealing treatment of the liquid injection hole 20 is realized by welding and combining the metal plate blank 40 and the top cover 10 into a whole. The sealing method comprises steps 201 to 203; the following are described separately.

In step 201, the main body of the sealing nail 30 is accommodated in the pouring hole 20, and the outer end edge of the sealing nail 30 is lapped on the outer surface of the top cover 10 or the outer end surface of the sealing nail 30 protrudes out of the outer surface of the top cover 10.

Referring to fig. 6 and 7, the pour hole 20 is designed as a single cylindrical through hole structure, and the seal nail 30 with a size specification precisely matched with that of the pour hole 20 is selected to seal the pour hole 20, the seal nail 30 may be a cylindrical structure or a structure with an axial cross-section approximately in the shape of a "T", such that at least a portion of the seal nail 30 (specifically, the outer end of the seal nail 30) is exposed on the outer surface of the top cover 10, so as to directly use the seal nail 30 to make stacking contact with the metal slab 40, thereby forming a stroke distance between the metal slab 40 and the outer surface of the top cover 10, which allows the metal slab 40 to move at a high speed.

At step 202, the metal blank 40 is stacked on the outer end surface of the sealing nail 30 and covers the sealing nail 30 such that there is a space between the metal blank 40 and the outer surface of the top cap 10.

Referring to fig. 6 and 7, the surface area of the metal plate blank 40 should be larger than the outer end surface of the sealing nail 30, so as to cover the sealing nail 30 or the structural gap between the sealing nail 30 and the liquid injection hole 20; meanwhile, the metal plate blank 40 is supported by the sealing nails 30, so that the metal plate blank 40 and the top cover 10 are arranged in parallel at intervals.

And step 203, combining the metal plate blank 40 and the top cover 10 into a whole by adopting an electromagnetic pulse welding mode to finish the sealing of the liquid injection hole 20.

Referring to fig. 6 and 8, after the discharge coil 60 is disposed on the side of the metal slab 40 away from the top cover 10, the discharge coil 60 faces the metal slab 40, so that the metal slab and the discharge coil are disposed in a vertically opposite manner, and after the capacitor 70 is turned on to discharge electricity to the discharge coil 60, due to the spacing effect of the sealing nails 30 or the outer end edge portions thereof, the metal slab 40 can move downward at a high speed in the peripheral area of the sealing nails 30 under the action of electromagnetic induction, and collide with the outer surface of the top cover 10 at a high speed, so that the metal slab and the top cover are welded and combined into a whole, and the sealing of the liquid injection hole 20 is realized. In this embodiment, since the accommodating sinking groove 50 is omitted, only the welding of the metal slab 40 can be completed, and the metal slab 40 cannot be cut and punched simultaneously, so that when selecting the metal slab 40, it is only necessary to select the metal slab 40 having an appropriate size on the premise that the area covered by the metal slab 40 is larger than the area of the outer end surface of the seal nail 30, and it is not necessary to precisely screen the specification and size of the metal slab 40 or strictly manufacture the metal slab 40 in accordance with the preset specification and size.

The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.