WO2018192072A1 - Lithium-ion power battery thermal protection connection structure and connection method therefor - Google Patents

Abstract

A lithium-ion power battery thermal protection connection structure, comprising a copper bar (1) and a cell copper plate electrode (2) parallel to the copper bar, the copper bar (1) is connected with the cell copper plate electrode (2) by means of a fusible metal block (4); a separator (3) is positioned between the copper bar (1) and the cell copper plate electrode (2) and clings to a side face of the copper bar (1); the set area of the separator (3) is not smaller than the frontal projected area of the copper bar (1) and the cell copper plate electrode (2) on the separator (3); a hole matched with the fusible metal block (4) is formed on the separator (3); and the separator (3) is connected with the outer edge of the cell electrode copper plate (2) by means of a flow guide slot (5). By mainly utilizing the characteristic of low melting point of a low-melting-point metal block, when the fusible metal block is heated to the temperature of the melting point by means of constant-temperature heating, the fusible metal block may be melted and then bonded with a bus-bar and a cell electrode that are made of copper, and curing and welding are realized after cooling; if once cell temperature is too high due to misuse, the low-melting-point metal block may quickly melt, so the connection between the cell and the bus-bar is broken, thereby achieving a self-protection effect on the entire battery pack.

Description

Lithium ion power battery thermal protection connection structure and preparation method thereof Technical field

The invention belongs to the technical field of batteries, and in particular relates to a connection structure of a lithium ion battery and a manufacturing method thereof.

Background technique

In recent years, lithium batteries have been widely used in electric vehicles, energy storage power stations, power tools and other places due to their high energy density, high average voltage, high output power and long service life. A plurality of cells are connected in series and parallel through a bus bar, and the currents of the plurality of cells are collected to form a large-capacity battery pack, thereby achieving the power supply requirement. With the gradual expansion of the scope of application, the safety of lithium batteries has received extensive attention.

During the charging and discharging process of the lithium battery, the battery itself and the components on the large current path generate heat, although the management system circuit of the battery pack can control the lithium battery to charge and discharge in a certain temperature range, but in some extreme cases If the collision battery pack is squeezed or an internal short circuit occurs in a single cell, one or more batteries of the battery will generate a strong internal reaction and generate a large amount of heat, which will cause the temperature inside the battery pack to continuously rise. And transfer to each other to cause a chain reaction of each battery cell in the entire battery pack.

On the other hand, if the lithium battery is internally or externally short-circuited or overcharged, the lithium battery can generate high heat, causing some of the electrolyte to vaporize, and the lithium battery casing is broken and exploded, especially for the lithium battery used as the vehicle power source. Group, once a lithium battery explodes, it will lead to the explosion of lithium batteries connected to it due to the diffusion of heat, which not only seriously affects the driving of the vehicle, but also brings hidden dangers to the people, economic property and so on. s damage. When the charging voltage of a single cell is higher than 4.2V or the discharging voltage is lower than 2.4V, the battery capacity will be permanently reduced, and the positive and negative electrodes will be short-circuited, causing the lithium battery to explode. Also, when the current of the lithium battery is too large, the lithium ions do not have time to enter the storage cell, and may accumulate on the surface of the material, which may also cause the lithium battery to explode.

Therefore, it is necessary to protect each lithium battery to prevent its overheating from being out of control, thereby ensuring the safe operation of the battery pack.

Summary of the invention

In view of the deficiencies in the art, it is an object of the present invention to provide a lithium ion power battery thermal protection connection structure.

A second object of the invention is to propose a method of preparing the thermally protected joint structure.

A third object of the present invention is to provide a lithium ion power battery pack including the thermal protection connection structure.

The technical solution for achieving the above object of the present invention is:

A lithium ion power battery thermal protection connection structure includes a bus bar connecting the battery core electrodes, and the bus bar and the battery core electrode are welded and connected by a low melting point metal block.

Further, the melting point of the fusible metal block is 70-140 ° C, the material of the bus bar and the cell electrode is copper, and the shape of the fusible metal block is cylindrical or prismatic. The length of the molten metal block is 2-10 mm. Preferably, the length is 5 mm and the diameter is 4 mm; the block-shaped low melting point metal screw has a length of 2 to 10 mm, a width and a thickness of 2 to 9 mm, preferably 5*4*4 mm or 4*3*3 mm.

Wherein the fusible metal block includes a connecting portion, the end portion of the connecting portion is provided with a boss extending outward in the axial direction thereof, and the bus bar row is provided with an interference fit with the boss The hole and the bus bar are fixed to the step formed by the boss and the fusible metal block through the mounting hole;

One of the preferred technical solutions of the present invention is that the fusible metal block is cylindrical, and the column body is provided with external threads. The cylindrical fusible metal block has a length of 2-10 mm and a diameter of 2-10 mm.

Wherein, the top surface of the battery core electrode is welded with a fixing nut, one end of the low melting point metal screw is screwed to the fixing nut, and the other end is welded to the bus bar;

Or a fixing nut is welded to the top end surface of the battery core, and a through hole is formed in the bus bar; one end of the low melting point metal screw is screwed to the fixing nut, and the other end passes through the through hole. After fixing with a lock nut;

Or a fixing nut is welded to the top end surface of the battery core electrode, and a through hole is formed in the bus bar; the low melting point metal screw is a boss having a large end and a small end, and the large end diameter is 2-10 mm. The small end has a diameter of 40 to 80% of the diameter of the large end, the large end of which is screwed to the fixing nut, and the small end (with no thread on the small end) passes through the through hole and is welded to the bus bar.

Further, the intermediate sleeve of the low melting point metal block is provided with a separating plate, and the outer side of the separating plate The circumference side is connected to the outer peripheral side of the cell electrode through a baffle to form a collecting groove.

The lithium ion power battery thermal protection connection structure comprises a bus bar and a cell electrode cover plate disposed in parallel with the bus bar, and the bus bar is connected to the cell electrode cover through the fusible metal block, and is located at the bus bar and A partition plate is disposed between the battery core cover plates, and the set area of the partition plate is not less than an orthographic projection area of the bus bar and the electrode cover plate, and the plate is provided with the fusible The metal block is matched with the opening, and the isolating plate is connected to the outer edge of the cell electrode cover through the flow guiding groove; the separating plate and the guiding groove are all made of a flame retardant material.

Wherein, the separating plate and the guiding groove are mutually pre-formed independently of one of the following flame retardant materials: flame retardant polypropylene, flame retardant polystyrene or flame retardant polyethylene. For example, it may be a halogen-free environment-friendly polypropylene material.

Optionally, the fusible metal is one of a tin-bismuth alloy, a gallium-based alloy, a wood alloy, and an indium-bismuth alloy.

A safe lithium battery pack comprising the lithium ion power battery thermal protection connection structure of the present invention.

The method for preparing a lithium ion power battery thermal protection connection structure includes an operation of soldering a low melting point metal block to the bus bar and an operation of connecting a low melting point metal block to the battery core electrode, and a low melting point metal block The manner in which the cell electrodes are connected is by bolting or welding; the steps of soldering the low melting point metal block to the bus bar are as follows:

S11 uses a clamp to place the low melting point metal block directly above the bus bar according to the welding position, and heats the bus bar to the melting point temperature of the low melting point metal block using a constant temperature heat gun;

S12 uses a cylinder to press the low melting point metal block to the top end surface of the bus bar, and when the contact surface of the low melting point metal block and the bus bar melts, the constant temperature heat gun is turned off;

S13 closes the constant temperature heat gun, and cools the contact surface of the low melting point metal block and the bus bar. After the low melting point metal block is solidified, the low melting point metal block is connected with the bus bar to be integrated;

S14, the low melting point metal block integrally connected with the bus bar is placed directly above the battery core electrode, and the battery core electrode is heated to a melting point temperature of the low melting point metal block by using a constant temperature heat gun;

S15 uses a cylinder to press the low melting point metal block to the top end surface of the battery core electrode, and when the contact surface of the low melting point metal block and the battery core electrode melts, the constant temperature heat gun is turned off;

S16 blows the contact surface of the low melting point metal block and the battery core electrode while turning off the constant temperature heat gun. The wind is cooled, and after the low melting point metal block is solidified, the electric core and the low melting point metal block are connected to the bus bar.

The steps of soldering the low melting point metal block to the battery core electrode are as follows:

S21 uses a clamp to place the low melting point metal block directly above the electrode of the battery according to the welding position, and heats the battery electrode to the melting point temperature of the low melting point metal block using a constant temperature heat gun;

S22 uses a cylinder to press the low melting point metal block to the top end surface of the battery core electrode, and when the contact surface of the low melting point metal block and the battery core electrode melts, the constant temperature heat gun is turned off;

S23 closes the constant temperature hot air gun, and cools the contact surface of the low melting point metal block and the battery core electrode, and after the low melting point metal block is solidified, the low melting point metal block and the battery core electrode are integrally connected;

S24 places a low-melting-point metal block integrally connected with the battery core electrode directly above the bus bar, and heats the bus bar to a melting point temperature of the low-melting-point metal block by using a constant temperature heat gun;

S25 uses a cylinder to press the low melting point metal block to the top end surface of the bus bar or through the through hole on the bus bar, and when the contact surface of the low melting point metal block and the bus bar melts, the constant temperature heat gun is turned off;

S26 closes the constant temperature hot air gun, and cools the contact surface of the low melting point metal block and the bus bar. After the low melting point metal block is solidified, the electric core and the low melting point metal block are connected with the bus bar.

The connecting method includes a connecting device for conveying a fusible metal, a distance sensor provided at an exit of the transmission channel, a clamp for holding the fusible metal, and a welding unit for moving the battery up and down Lifting mechanism,

The welding unit and the lifting mechanism are both connected to the controller, the controller comprises a power adjustment module, a movement control module, a lifting control module and a distance detecting module; the input end of the distance detecting module is connected with the distance sensor, and the distance sensor is collected in real time. Distance information;

The input end of the power adjustment module is connected to the output end of the distance detection module, the output end of the power adjustment module is connected to the input end of the movement control module and the lifting control module, and the power adjustment module controls the movement control module according to the distance information output by the distance detection module. To drive the transmission channel and the fixture to operate, control the lifting control module to drive the lifting mechanism to operate.

Further, a resistance detecting device and a height measuring device for measuring the height of the fusible metal that is fused are connected between the soldered surface of the fusible metal and the battery core; and the height loss of the fusible metal before and after the soldering is controlled to be no more than 0.2. Mm.

The connecting device further includes: an output end of the resistance detecting device and an output end of the height measuring device are connected to an input end of the welding effect detecting module in the controller;

The output end of the welding effect detecting module is connected to the input end of the welding effect determining module to make the welding effect determining module judge whether the welding is qualified according to the welding effect. Resistance detection device (tested if the internal resistance is not more than 0.5mΩ).

The connecting device further includes a removal control module, and the input end of the removal control module is connected with the output end of the welding effect determination module to control the removal device according to the result determined by the welding effect determination module, and the unqualified welding surface of the battery core is performed. Dismantled, the dismantling device is a robot;

The controller further includes a cleaning and polishing control module, wherein the input end of the cleaning and polishing control module is connected with the output end of the removal control module, and the cleaning and polishing control module controls the cleaning and polishing device to polish the unqualified welding surface of the battery core for a preset time. Finishing sanding within 10s;

The output of the cleaning and polishing control module is connected to the input end of the power conditioning module. After the cleaning and polishing control module is ground for a preset time, the power adjustment module controls the lifting mechanism to move the battery up to be welded with the fusible metal.

The beneficial effects of the invention are:

The thermal protection connection structure proposed by the invention is connected between the bus bar and the copper plate of the cell top cover by using a fusible metal block. When the battery is in an uncontrollable environment, the fusible metal block can be quickly melted, thereby cutting off the single The physical electrical connection between the body cell and the bus bar, quickly isolates the over-temperature cell, prevents the cell from being discharged in an over-temperature condition, causing a heat accident such as a fire or explosion. The invention uses a precision adjustable electronic switch circuit module to be connected between the bus bar and the core cover copper plate to realize the welding of the fusible metal block to the high current discharge of the battery core to the millisecond level. Since the resistance of both ends of the fusible metal block is first melted, it is reliably connected between the bus bar and the core cap copper plate, and the structure of the fusible alloy cylinder is maintained, and the fusible metal block and the bus bar are improved. The reliability of the copper plate connection of the cell top cover.

The invention uses a precision adjustable electronic switch circuit module for fusible metal blocks and bus bars and electricity The connection of the core electrode enables the welding of the fusible metal block to a large current discharge of the battery core to the millisecond level. Since the resistance of both ends of the fusible metal block is first melted, it is reliably connected between the bus bar and the core cap copper plate, and the structure of the fusible alloy cylinder is maintained, and the fusible metal block and the bus bar are improved. The reliability of the copper plate connection of the cell top cover.

DRAWINGS

Figure 1 is a schematic view of the structure of the present invention;

2 is a schematic view showing the welding of the fusible metal block and the electric core electrode copper plate of the present invention;

3 is a schematic view showing the welding of the fusible metal block and the bus bar of the present invention.

Figure 4 is a schematic view showing the first structure of the present invention;

Figure 5 is a schematic structural view of Embodiment 5;

Figure 6 is a cross-sectional view showing the connection of Embodiment 6 of the present invention;

Figure 7 is a cross-sectional view showing the connection of Embodiment 7 of the present invention;

8 is a schematic view showing the connection of a fusible metal block, a bus bar, and a cell top copper plate according to Embodiment 7 of the present invention;

Figure 9 is a schematic structural view of a fusible metal block of Embodiment 7;

Figure 10 is a schematic view of the embodiment 7 after the fusible metal block is welded to the bus bar and the core cap copper plate;

Figure 11 is a test view of the fusible metal block of Example 7 after being welded to the bus bar and the core cap copper plate.

12 is a schematic structural view of a fully automatic welding device for a lithium battery module in Embodiment 8;

Figure 13 is a schematic view showing the detection of the welding effect of the battery cells in the eighth embodiment;

Figure 14 is a schematic structural view of a controller in Embodiment 8;

15 is a flow chart showing a control method of a fully automatic welding device for a lithium battery module in Embodiment 8.

In the figure, 1. Confluence copper row, 2. Battery electrode copper plate, 3. Isolation plate, 4. Fusible metal block, 41. Connection part, 42. Boss, 43. Small end of low melting metal block, 44. Cone-shaped protrusion, 5. Diversion groove, 51 baffle, 6. Battery; 7. Battery electrode; 8. Low-melting metal screw, 81. Lock nut. 82. fixing nut, 9. electronic switch circuit module, 10. welding head, 11. transmission channel, 13. fixture. 14. Welding pen, 15 elastic connecting piece, 16. Resistance detecting device, 17. Height measuring device.

detailed description

The invention is illustrated below by the preferred embodiment. It should be understood by those skilled in the art that the present invention is not intended to limit the scope of the invention.

In the examples, the means used are all conventional means in the art unless otherwise specified.

Example 1

As shown in FIG. 1-3, the lithium ion power battery thermal protection connection structure of the embodiment includes a bus bar 1 and a cell electrode copper plate 2 disposed in parallel with the bus bar 1 , and the bus bar 1 passes through the fusible metal block. 4 is connected to the battery electrode copper plate 2, and is disposed between the bus bar copper plate 1 and the battery core electrode plate 2 and is closely attached to the side of the bus bar 1 to be provided with a partition plate 3 made of a flame retardant material. The area is not less than the orthographic projection area of the bus bar 1 and the electrode electrode copper plate 2 to improve the effect of the bus bar 1 and the cell electrode 2, and to avoid heat transfer and conduction, and is disposed on the board 3 There is an opening matching the fusible metal block 4; the isolating plate 3 is connected to the outer edge of the battery electrode copper plate 2 through a flow guiding groove 5 made of a flame retardant material, the separating plate 3, the guiding groove 5 and the battery core The electrode copper plate 2 forms a space for accommodating the melted fusible metal, and the ratio of the space to the volume of the fusible metal is 2:1, which prevents the fusible metal from flowing into the battery to cause a short circuit of the battery.

The fusible metal block 4 includes a connecting portion 41, and the end portion of the connecting portion 41 is provided with a boss 42 extending outward in the axial direction thereof, and the end portion is provided with a boss 42 extending outward in the axial direction thereof, the boss The material of 42 is the same as that of the fusible metal block 4, and the boss 42 and the molten metal block 4 are integrally formed. The bus bar 1 is provided with a mounting hole that is interference-fitted with the boss 42. The bus bar 1 is fixed to the step formed by the boss 42 and the fusible metal block 4 through the mounting hole, and the fusible metal block 4 is a boss. 42 is connected to the bus bar 1 to increase the contact surface of the fusible metal block 4 and the bus bar 1 to improve the connection stability of the bus bar 1 and the fusible metal block 4. The fusible metal block 4 may be in the shape of a cylinder or a prism. This embodiment is preferably a cylindrical shape, and the fusible metal block is a tin-bismuth alloy having a melting point of 138 °C.

When the thermal runaway of the battery occurs, the fusible metal is melted by heat, thereby cutting off the physical electrical connection between the cell core and the bus bar, quickly isolating the overheated cell, preventing the cell from being discharged under an over-temperature condition, causing heat buildup to ignite, Serious failures such as explosions.

A lithium ion power battery thermal protection connection method of the embodiment includes the following steps:

S1: making the fusible metal block 4, using a special fixture to place the fusible metal block 4 in the arrangement position Confluence copper row 1;

S2: Select two probes, one end of the two probes is connected to the bus bar 1 , and the other ends of the two probes are respectively connected with a high-power current source with adjustable amplitude and pulse width, and pass the high-power current. The source heats the bus bar 1 and immediately cuts off the current signal when the contact surface of the fusible metal block 4 melts, and at the same time blows and cools the fusible metal block 4, so that the fusible metal block 4 is solidified and welded in the bus bar 1 on.

S3: placing the other end of the fusible metal block 4 to which the bus bar 1 is soldered is placed on the battery electrode copper plate 2, and connecting one end of the two probes to the battery electrode copper plate 2, and powering it through a high-power current source The core electrode copper plate 2 is heated, and when the contact surface of the fusible metal block 4 is melted, the current signal is immediately cut off, and at the same time, the fusible metal block 4 is blown and cooled, and the fusible metal block 4 is solidified and welded on the battery core electrode plate 2. . In this embodiment, the instantaneous current of the pulse is 100-150 A, and the time is 0.3 s. The battery electrode of the battery core is welded by 7 pulses, and the copper bus of the bus is welded by 2 pulses.

In the invention, when the fusible metal block 4 is welded to the bus bar row 1 and the battery electrode electrode plate 2, it may be selected to be welded to the bus bar 1 and then to the cell electrode plate 2 according to actual conditions, or firstly with the cell electrode. The copper plate 2 is welded and then welded to the bus bar 1 . When the fusible metal block 4 is located below the bus bar 1 and the fusible metal block 4 and the bus bar 1 are welded, the cylinder can be used to press the fusible metal block 4 to make the fusible metal block 4 and the bus bar. 1 Full contact for easy soldering.

After welding, it was found through drawing and hammering that the weld surface of the fusible metal and the bus bar, the fusible metal and the cell cover were high in strength, and the mechanical strength of the bus bar main body was the same. After welding, the resistance between the bus bar and the fusible metal-cell cover is only 0.2mΩ, which has negligible effect on battery performance.

Example 2

A safety lithium battery pack using a constant temperature heating connection cell, comprising a battery core 6 and a bus bar connecting the battery core electrodes 7, and the bus bar and the battery core electrode 7 are weldedly connected by a fusible metal block 4. In this embodiment, the bus bar and the cell electrode cover are made of copper.

In the present embodiment, the material of the fusible metal block 4 is an indium-bismuth alloy having a melting point of 90 °C.

As shown in FIG. 4, the fusible metal block 4 has a cylindrical shape, and its both ends are respectively welded to the bus bar 1 and the electrode core. As shown in FIG. 1 , the fusible metal block 4 is a boss having a large end and a small end, and has a large end length of 5 mm, a diameter of 4 mm, a small end diameter of 3 mm, and a height of 4. mm. Opening and setting up The small end 3.1 of the low melting point metal block is matched with the through hole; the small end 43 of the low melting point metal block passes through the through hole on the bus bar and is welded to the inner wall of the through hole, and the big end of the fusible metal block 4 is electrically connected The core electrode 7 is welded.

In the present embodiment, the separator 3 is interposed in the middle of the fusible metal block 4, and the outer peripheral side of the separator 3 is connected to the outer peripheral side of the cell electrode via the baffle 51 to form a collecting groove. The collecting trough and the separating plate are pre-formed before welding, and the material is a flame-retardant halogen-free environment-friendly polypropylene material, and the size is matched with the module frame, and the collecting trough and the separating plate are assembled after the fusible metal piece is welded. The collecting tank collects the molten metal when the readily soluble metal mass is thermally protected and melted.

The invention relates to a connection method of a safe lithium battery pack using a constant temperature heating connection cell, and there are three connection modes, and one of the connection methods is as follows:

(1) using a clamp to place the low melting point metal block directly above the bus bar according to the welding position, and heating the bus bar to the melting point temperature of the low melting point metal block using a constant temperature heat gun;

(2) using a cylinder, pressing the low melting point metal block to the top end surface of the bus bar, and when the contact surface of the low melting point metal block and the bus bar is melted, the constant temperature heat gun is turned off;

(3) while the constant temperature heat gun is turned off, the contact surface of the low melting point metal block and the bus bar is blown and cooled, and after the low melting point metal block is solidified, the low melting point metal block is connected with the bus bar to be integrated;

(4) placing a low-melting-point metal block integrally connected with the bus bar directly above the electrode of the battery, and heating the electrode electrode to a melting point temperature of the low-melting metal block using a constant temperature heat gun;

(5) using a cylinder, pressing the low melting point metal block to the top end surface of the battery core electrode, and turning off the constant temperature heat gun when the contact surface of the low melting point metal block and the battery core electrode is melted;

(6) While the constant temperature heat gun is turned off, the contact surface of the low melting point metal block and the battery core electrode is blown and cooled, and after the low melting point metal block is solidified, the battery core and the low melting point metal block are connected with the bus bar.

Example 3

In this embodiment, the fusible metal block is prismatic and has a size of 5*4*4 mm. The other structure is the same as that of the embodiment 2. The connection method is as follows:

(1) using a jig to place the low-melting metal block directly above the electrode of the battery according to the welding position, and heating the electrode of the battery to the melting point temperature of the low-melting metal block using a constant temperature heat gun;

(2) Using a cylinder, press the low-melting metal block down to the top surface of the cell electrode, when the low melting point gold When the contact surface between the block and the electrode of the battery is melted, the constant temperature heat gun is turned off;

(3) while closing the constant temperature heat gun, cooling the contact surface of the low melting point metal block and the battery core electrode, and after the low melting point metal block is solidified, the low melting point metal block and the battery core electrode are integrally connected;

(4) placing a low melting point metal block integrally connected with the electrode core electrode directly above the bus bar, and heating the bus bar to a melting point temperature of the low melting point metal block using a constant temperature heat gun;

(5) using a cylinder, pressing the low-melting metal block down to the top surface of the bus bar, and turning off the constant temperature heat gun when the contact surface of the low-melting metal block and the bus bar melts;

(6) While the thermostatic hot air gun is turned off, the contact surface of the low melting point metal block and the bus bar is blown and cooled, and after the low melting point metal block is solidified, the electric core and the low melting point metal block are connected with the bus bar.

After welding, it was found through drawing and hammering that the weld surface of the fusible metal and the bus bar, the fusible metal and the cell cover were high in strength, and the mechanical strength of the bus bar main body was the same. After welding, the resistance between the bus bar and the fusible metal-cell cover is only 0.1mΩ, which has negligible effect on battery performance.

Example 4

The third connection of the structure of Embodiment 2 is as follows:

(1) Using a jig, place the large end of the boss-shaped low-melting-point metal block directly above the cell electrode according to the welding position, and use a constant-temperature heat gun to the cell electrode (the material of the bus bar 4 and the cell electrode 2 are both Copper). Heating to a melting point temperature of the low melting point metal block;

(2) using a cylinder, pressing the large end of the low melting point metal block to the top end surface of the battery core electrode, and turning off the constant temperature heat gun when the contact surface of the low melting point metal block and the battery core electrode is melted;

(3) while closing the constant temperature heat gun, cooling the contact surface of the low melting point metal block and the battery core electrode, and after the low melting point metal block is solidified, the low melting point metal block and the battery core electrode are integrally connected;

(4) placing a low melting point metal block integrally connected with the electrode core electrode directly above the bus bar, and heating the bus bar to a melting point temperature of the low melting point metal block using a constant temperature heat gun;

(5) Using a cylinder, pressing the small end of the low melting point metal block through the through hole in the bus bar, the small end of the low melting point metal block and the inner wall of the through hole of the bus bar, and the step surface of the low melting point metal block And sink When the contact surface formed by the end surface of the flow row is melted, the constant temperature heat gun is turned off;

(6) While the thermostatic hot air gun is turned off, the contact surface of the low melting point metal block and the bus bar is blown and cooled, and after the low melting point metal block is solidified, the electric core and the low melting point metal block are connected with the bus bar.

Example 5

As shown in FIG. 5, a safety lithium battery pack that uses a threaded lock to connect a battery cell includes a battery core 1 and a bus bar connecting the battery core electrodes, and the bus bar and the battery core electrode are connected by a low melting point metal screw 8 .

In the present embodiment, the low melting point metal screw 8 is a tin antimony alloy having a melting point of 138 °C. The cover plates of the bus bar and the cell electrode are made of copper.

There are three ways to connect the low melting point metal screw in the present invention:

One of the connection modes is as shown in FIG. 5: a fixing nut 3 is welded to the top end surface of the battery core electrode 2, and one end of the low melting point metal screw 4 is screwed to the fixing nut 3, and the other end and the bus bar are connected. 5 welding.

In a further embodiment, the welding is to heat and melt the low melting point metal screw, and to solidify on the bus bar.

Another connection mode is as shown in FIG. 7 : a fixing nut 3 is welded to the top end surface of the battery core electrode, and a through hole is formed in the bus bar row 1; one end of the low melting point metal screw 8 and the fixing nut 82 are provided. The threaded connection is made, and the other end is passed through the through hole and fixed by the lock nut 81.

The third connection manner is: a fixing nut 82 is welded to the top end surface of the battery core electrode, and a through hole is formed in the bus bar copper row 1; the low melting point metal screw 8 is a boss having a large end and a small end. The large end is screwed to the fixing nut 82, and the small end is welded to the bus bar after passing through the through hole.

The embodiment provides the above method for connecting a secure lithium battery pack using a threaded locking connection cell, wherein the first connection method steps are as follows:

(1) Select the same fixing nut as the top cover of the battery core and solder it to the electrode of the battery core;

(2) screwing one end of the low melting point metal screw to the fixing nut, and connecting the low melting point metal screw to the battery core;

(3) heating the bus bar to a melting point temperature of the low melting point metal screw using a constant temperature heat gun;

(4) using a cylinder, pressing a low-melting-point metal screw to the top end surface of the bus bar, and turning off the constant-temperature heat gun when the contact surface of the low-melting-point metal screw and the bus bar melts;

(5) While the thermostatic hot air gun is turned off, the contact surface of the low melting point metal screw and the bus bar is blown and cooled, and after the low melting point metal screw is solidified, the electric core, the low melting point metal screw and the bus bar are integrally connected.

After welding, it was found through drawing and hammering that the weld surface of the fusible metal and the bus bar, the fusible metal and the cell cover were high in strength, and the mechanical strength of the bus bar main body was the same. After welding, the resistance between the bus bar and the fusible metal-cell cover is only 0.1mΩ, which has negligible effect on battery performance.

Example 6

The second connection method of the structure of Embodiment 5 is as follows:

(1) Select the same fixing nut as the top cover of the battery core and solder it to the electrode of the battery core;

(2) screwing one end of the low melting point metal screw to the fixing nut, and connecting the low melting point metal screw to the battery core;

(3) opening a through hole corresponding to the low melting point metal screw on the bus bar, and passing the other end of the low melting point metal screw through the through hole and fixing with a lock nut, thereby connecting the battery core and the low melting point metal screw with The bus bars are connected together.

Example 7

The third connection method of the structure of Embodiment 5 is as follows:

(1) Select the same fixing nut as the top cover of the battery core and solder it to the electrode of the battery core;

(2) screwing the large end of the boss-shaped low melting point metal screw to the fixing nut, and connecting the low melting point metal screw to the battery core;

(3) Opening a through hole corresponding to the low melting point metal screw on the bus bar, placing the small end of the low melting point metal screw directly above the through hole on the bus bar, and heating the bus bar to a low temperature using a constant temperature heat gun The melting point temperature of the melting point metal block;

(4) Using the cylinder, press the small end of the low melting point metal block and pass through the through hole in the bus bar, when the small end of the low melting point metal block and the inner wall of the through hole of the bus bar, and the step surface of the low melting point metal block Closing the constant temperature heat gun at the moment when the contact surface formed by the end surface of the bus bar is melted;

(5) While the thermostatic hot air gun is turned off, the contact surface of the low melting point metal block and the bus bar is blown and cooled, and after the low melting point metal block is solidified, the electric core and the low melting point metal block are connected with the bus bar.

Example 7

As shown in FIGS. 8-11, a lithium ion power battery thermal protection connection method includes the following steps:

S1: a cylindrical fusible metal block 4 is selected, and the two end faces of the fusible metal block 4 are respectively provided with a plurality of tapered protrusions 44; the tapered protrusions 44 enable the fusible metal block 4 to be welded first. The columnar structure of the main body is financialized, thereby facilitating the connection of the fusible metal block 4.

S2: placing the bus bar 1 of the lithium ion battery in parallel with the cell electrode copper plate 2, and placing the fusible metal block 4 between the bus bar 1 and the electrode electrode plate 2, so that the two of the fusible metal block 4 The ends are in close contact with the bus bar and the electrode electrode copper plate 2 respectively;

S3: using a precision adjustable electronic switch circuit module 9 connected between the bus bar 1 and the cell top cover 2, and setting the pulse time, the number of pulses and the current of the switch electronic switch circuit module 9; specifically, The instantaneous current of the pulse is set to 100-150A, the pulse time is 0.1~0.5s, the cell electrode cover is welded by 5~8 pulses, and the busbar copper is welded by 2~5 pulses.

S4: The electronic switch circuit module 9 is activated to discharge the battery core, and the two end faces of the fusible metal block 4 are heated and the tapered protrusions 44 are melted, because the resistance of the both ends of the fusible metal block 4 is first melted, thereby The fusible metal block 3 is reliably connected between the bus bar 1 and the electrode electrode copper plate 2, and maintains the structure of the fusible alloy cylinder. After cooling, the fusible metal block 4 and the bus bar 1 and the cell electrode plate are cooled. 2 welded together.

In the above steps, the switch circuit module 9 includes an impedance test unit 91, and the soldering result of the fusible metal block 3 and the bus bar and the electrode electrode copper plate 2 is tested by the impedance test unit 91 to confirm whether the solder passes, if not Pass through to continue welding to pass. The fusible metal block 4 may be provided in a cylindrical shape or a prism shape according to actual needs. The present invention is preferably cylindrical, and the melting point of the fusible metal block 4 is 70 to 140 °C.

The invention connects between the bus bar row 1 of the lithium battery module and the battery core electrode plate 2 through a low melting point, high conductivity alloy, and the fusible metal block 4 and the bus bar are arranged by the method of the invention. The battery electrode copper plate 2 is reliably connected, which can serve as a flow guiding function and can also serve as a physical layer of the battery core. Thermal protection. Once the cell is overheated for any reason, the fusible metal block 4 can be quickly blown, and the connection between the cell and the bus bar 1 is disconnected, preventing the chain reaction between the cells from causing thermal runaway, starting from the entire module. To protection.

Example 8

As shown in Figure 12-15, this embodiment discloses a fully automatic welding device for a lithium battery module, including:

From the transmission passage 11 of the fusible metal 12, the distance sensor provided at the outlet of the transmission passage 11, the clamp 13 for holding the fusible metal block 4, and the welding head 10 composed of the pair of welding pens 14, the battery core 6 passes The lifting mechanism is moved up and down in contact with the welding head 10, and the upper surface of the welding head 10 in contact with the battery core 6 is provided with an elastic connecting member 15;

The welding head 10 and the lifting mechanism are both connected to the controller, and the controller comprises a power adjustment module, a movement control module, a lifting control module and a distance detecting module;

The distance between the input end of the distance detecting module and the distance sensor is used to collect distance information of the distance sensor in real time;

The input end of the power adjustment module is connected with the output end of the distance detecting module, and the power connection is connected, the output end of the power adjustment module is connected with the input end of the mobile control module and the lifting control module, and the power adjustment module outputs the distance information according to the distance detecting module. The movement control module is controlled to drive the transmission channel 11 and the clamp 13 to operate, and the elevation control module is controlled to drive the lifting mechanism to operate.

Specifically, the power supply in this embodiment includes, but is not limited to, an alternating current of 22V or 380V.

Specifically, the shape of the fusible metal block 6 is not limited in this embodiment, and may be a cylindrical shape, a cubic shape, a cylindrical and cubic mixed shape, a tapered shape, and the like.

Preferably, the fusible metal block 6 in this embodiment is in the shape of a segment to facilitate welding with the cell welding surface.

It should be noted that the power adjustment module in this embodiment includes a time adjustment unit and a current adjustment unit to control the output current and output time of the power source. Among them, the working process of the automatic welding equipment is: when the welding starts, the power output module is used to adjust the appropriate output current and output time, the segmented fusible metal is added to the transmission channel of the fusible metal 12, and the mobile control module will be fusible. The metal moves to the exit of the channel. When the fusible metal is exposed to a certain length, such as 1/2 or 1/3, the clamp 13 will be exposed. The fusible metal block 6 is clamped, and the cell moves up and contacts the fusible metal 12, and the soldering pens on both sides are dropped to perform soldering.

Further, as shown in FIG. 13, a resistance detecting device 40 and a height measuring device 41 for measuring the height of the fusible metal block are connected between the fusible metal block and the welding surface of the battery cell 2; the resistance detecting device 40 The output end of the height measuring device 41 is connected to the input end of the welding effect detecting module in the controller 30;

The output end of the welding effect detecting module is connected to the input end of the welding effect determining module to make the welding effect determining module judge whether the welding is qualified according to the welding effect.

Further, the fully automatic welding device in this embodiment is placed on a movable three-dimensional platform, and the position of the entire device can be adjusted by moving the three-dimensional platform.

Further, the controller further includes a removal control module, and the input end of the removal control module is connected with the output end of the welding effect determination module to control the removal device according to the result determined by the welding effect determination module, and the unqualified battery cell The welded surface is removed.

It should be noted that, in this embodiment, after the welding is completed, the transmission channel 11 will transport the next fusible metal 12 to the fixture 13, and at the same time, the battery core moves down, the welding pen is lifted, and the welding effect detection module is started. Welding effect determination module. The welding effect detecting module includes detecting the electric resistance between the welded fusible metal and the welding surface of the electric core and the height of the fusible metal piece welded on the welding surface of the electric core. The welding effect determination module determines the height of the welded fusible metal and the electrical resistance between the welded surface and the fusible metal. When both parameters meet the preset requirements, it is determined that the welding is qualified, and after the determination is passed, the welding head 10 moves. Welding to the next or next group of batteries, when the welding does not meet the requirements, the removal control module will be started, and the removal control module will control the removal device to remove the unqualified welding surface of the battery core. This ensures the accuracy and reliability of the welding of the welding surface of the battery core and the fusible metal, and avoids the occurrence of such phenomena as the virtual welding.

Further, the controller further comprises a cleaning and polishing control module, wherein the input end of the cleaning and polishing control module is connected with the output end of the removal control module, and the cleaning and polishing control module controls the cleaning and polishing device to polish the unqualified welding surface of the battery core. time;

The output end of the cleaning and polishing control module is connected with the input end of the power adjustment module, and the power adjustment module controls the lifting mechanism to move the battery up and after the cleaning and polishing control module is polished for a preset time. Fused metal welding.

It should be noted that when the dismantling device removes the fusible metal of the unqualified cell welding surface, it is also necessary to polish and clean the cell welding surface in order to re-weld the unqualified cell welding surface.

Further, the apparatus includes at least one weld head 10. In practical applications, by mounting a plurality of welding heads 10 in one apparatus, multiple or more sets of batteries can be welded at the same time, which greatly improves the welding efficiency.

Further, the dismantling device is a robot.

Further, the movement control module comprises a transfer control unit and a clamp control unit, and the output end of the transfer control unit is connected to the transmission channel 11 to drive the transmission channel for transmission, and the output end of the clamp control unit is connected to the clamp 13 and the drive clamp 13 is clamped. Or open.

It should be noted that, in this embodiment, a motor may be used to drive the transmission channel 11 and the clamp 13 to operate.

As shown in FIG. 15, the embodiment further discloses a control method for the fully automatic welding device of the above lithium battery module, comprising the following steps S1 to S4:

S1, the starting device, the power regulating module controls the transmitting unit to transport a fusible metal block to the channel outlet by adjusting the output current and the output time of the power source;

S2. The distance detecting module outputs a control signal to the fixture control unit when determining that the exposed length is a predetermined length according to the distance information of the fusible metal collected by the distance sensor at the exit of the channel;

S3. The fixture control unit control fixture 13 clamps the fusible metal at the exit position of the channel;

S4. When the lifting control module controls the battery cell 6 to move up to contact with the fusible metal 12, the welding pens 14 on both sides are dropped for welding.

Further, the control method further includes the following steps:

The welding effect detecting module determines whether the resistance and the height meet the requirements according to the resistance information and the height information respectively output by the resistance detecting device 16 and the height measuring device 17;

The welding effect determination module determines that the welding is unqualified when either the resistance or the height does not meet the requirements. In the present embodiment, the setting resistance was 0.5 mΩ or less, and the height loss due to welding was 0.2 mm or less.

Further, the above method further includes the following steps:

When it is judged that the welding is unqualified, the removal control module controls the removal device to remove the fusible metal on the welding surface of the battery that does not meet the requirements;

The cleaning and polishing control module controls the cleaning and polishing device to polish and clean the welding surface of the battery core;

After polishing the preset 10 s duration, the movement control module 3 controls the movement of the fusible metal block 4 to re-weld with the cell welding surface.

The above embodiments are merely illustrative of the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Variations and modifications are intended to fall within the scope of the invention as defined by the appended claims.

Industrial applicability

The invention discloses a lithium ion power battery thermal protection connection structure, a bus bar copper row and a battery core electrode plate arranged in parallel with the bus bar row, and the bus bar row is connected to the battery electrode plate through the fusible metal block, and is located at the bus bar and the electricity. The side surface of the core electrode copper plate and adjacent to the bus bar row is provided with a partition plate, and the set area of the partition plate is not less than the orthographic projection area of the bus bar and the electrode electrode copper plate thereon, and the partition plate is provided with An opening matching the fusible metal block, the spacer being connected to the outer edge of the battery electrode copper plate through the flow guiding groove. The invention utilizes the low melting point characteristic of the low melting point metal block mainly, and when it is heated to its melting point temperature by the constant temperature heating method, it melts and adheres to the copper bus bar and the battery core electrode, and solidifies and welds after cooling. . Once the battery is overheated due to abuse, the low-melting metal block can be quickly blown, thereby disconnecting the connection between the battery and the busbar, and self-protecting the entire battery pack.

Claims (15)

A lithium ion power battery thermal protection connection structure comprises a bus bar connecting the battery core electrodes, wherein the bus bar and the battery core electrode are welded and connected by a low melting point metal block. The melting point of the fusible metal block is 70-140 ° C, the material of the bus bar and the cell electrode is copper, and the shape of the fusible metal block is cylindrical or prismatic, and the fusible metal block The length is 2-10mm. The thermal protection connection structure for a lithium ion power battery according to claim 1, wherein the fusible metal block comprises a connecting portion, and an end portion of the connecting portion is provided with a boss extending outward in the axial direction thereof. The bus bar row is provided with a mounting hole that is interference-fitted with the boss, and the bus bar is fixed to the step formed by the boss and the fusible metal block through the mounting hole. The lithium ion power battery thermal protection connection structure according to claim 1, wherein the fusible metal block is cylindrical, the column body is provided with external threads, and the length of the cylindrical fusible metal block is 2- 10mm, diameter 2-10mm. The thermal protection connection structure of a lithium ion power battery according to claim 4, wherein a fixing nut is welded to a top end surface of the battery core electrode, and one end of the low melting point metal screw is screwed to the fixing nut, The other end is welded to the bus bar; Or a fixing nut is welded to the top end surface of the battery core, and a through hole is formed in the bus bar; one end of the low melting point metal screw is screwed to the fixing nut, and the other end passes through the through hole. After fixing with a lock nut; Or a fixing nut is welded to the top end surface of the battery core electrode, and a through hole is formed in the bus bar; the low melting point metal screw is a boss having a large end and a small end, and the large end diameter is 2-10 mm. The small end has a diameter of 40 to 80% of the diameter of the large end, and the large end is screwed to the fixing nut, and the small end is welded to the bus bar after passing through the through hole. The thermal protection connection structure for a lithium ion power battery according to any one of claims 1 to 5, characterized in that: the intermediate sleeve of the low melting point metal block is provided with a partition plate, and the outer peripheral side of the partition plate passes through the deflector A collecting groove is formed to be connected to the outer peripheral side of the cell electrode. The thermal protection connection structure for a lithium ion power battery according to claim 6, comprising: a bus bar and a cell electrode cover plate disposed in parallel with the bus bar, wherein the bus bar is passed through the refractory gold The block is connected to the cell cover plate, and a partition plate is disposed between the bus bar and the cell electrode cover, and the set area of the spacer is not less than the orthographic projection of the bus bar and the electrode plate cover thereon The partitioning plate is provided with an opening matching the fusible metal block, and the isolating plate is connected to the outer edge of the cell electrode cover plate through the guiding groove; the separating plate and the guiding groove are both Made of flame retardant material. The thermal protection connection structure of a lithium ion power battery according to claim 7, wherein the spacer and the guide groove are independently prefabricated by one of the following flame retardant materials: flame retardant polypropylene, flame retardant Polystyrene or flame retardant polyethylene. The thermal protection connection structure for a lithium ion power battery according to any one of claims 1 to 5, wherein the fusible metal is one of a tin-bismuth alloy, a gallium-based alloy, a Wood alloy, and an indium-bismuth alloy. A safety lithium battery pack comprising the lithium ion power battery thermal protection connection structure according to any one of claims 1 to 9. The method for preparing a thermal protection connection structure for a lithium ion power battery according to any one of claims 1 to 9, characterized by comprising an operation of soldering a low melting point metal block to the bus bar and a low melting point metal block and the electricity The operation of the core electrode connection is such that the low melting point metal block is connected to the battery core electrode by bolting or welding; the steps of soldering the low melting point metal block to the bus bar are as follows: S11 uses a clamp to place the low melting point metal block directly above the bus bar according to the welding position, and heats the bus bar to the melting point temperature of the low melting point metal block using a constant temperature heat gun; S12 uses a cylinder to press the low melting point metal block to the top end surface of the bus bar, and when the contact surface of the low melting point metal block and the bus bar melts, the constant temperature heat gun is turned off; S13 closes the constant temperature heat gun, and cools the contact surface of the low melting point metal block and the bus bar. After the low melting point metal block is solidified, the low melting point metal block is connected with the bus bar to be integrated; S14, the low melting point metal block integrally connected with the bus bar is placed directly above the battery core electrode, and the battery core electrode is heated to a melting point temperature of the low melting point metal block by using a constant temperature heat gun; S15 uses a cylinder to press the low melting point metal block to the top end surface of the battery core electrode, and when the contact surface of the low melting point metal block and the battery core electrode melts, the constant temperature heat gun is turned off; S16 blows the contact surface of the low melting point metal block and the battery core electrode while turning off the constant temperature heat gun. The wind is cooled, and after the low melting point metal block is solidified, the electric core and the low melting point metal block are connected to the bus bar. The steps of soldering the low melting point metal block to the battery core electrode are as follows: S21 uses a clamp to place the low melting point metal block directly above the electrode of the battery according to the welding position, and heats the battery electrode to the melting point temperature of the low melting point metal block using a constant temperature heat gun; S22 uses a cylinder to press the low melting point metal block to the top end surface of the battery core electrode, and when the contact surface of the low melting point metal block and the battery core electrode melts, the constant temperature heat gun is turned off; S23 closes the constant temperature hot air gun, and cools the contact surface of the low melting point metal block and the battery core electrode, and after the low melting point metal block is solidified, the low melting point metal block and the battery core electrode are integrally connected; S24 places a low-melting-point metal block integrally connected with the battery core electrode directly above the bus bar, and heats the bus bar to a melting point temperature of the low-melting-point metal block by using a constant temperature heat gun; S25 uses a cylinder to press the low melting point metal block to the top end surface of the bus bar or through the through hole on the bus bar, and when the contact surface of the low melting point metal block and the bus bar melts, the constant temperature heat gun is turned off; S26 closes the constant temperature hot air gun, and cools the contact surface of the low melting point metal block and the bus bar. After the low melting point metal block is solidified, the electric core and the low melting point metal block are connected with the bus bar. The connecting method according to claim 11, wherein the connecting device comprises: a conveying path for conveying the fusible metal, a distance sensor provided at the exit of the conveying passage, and a jig for holding the fusible metal and welding Unit, a lifting mechanism for moving the battery cells up and down, The welding unit and the lifting mechanism are both connected to the controller, the controller comprises a power adjustment module, a movement control module, a lifting control module and a distance detecting module; the input end of the distance detecting module is connected with the distance sensor, and the distance sensor is collected in real time. Distance information; The input end of the power adjustment module is connected with the output end of the distance detection module, the output end of the power adjustment module is connected with the input end of the movement control module and the lifting control module, and the power adjustment module controls the movement control according to the distance information output by the distance detection module. The module drives the transmission channel and the clamp to operate, and controls the lifting control module to drive the lifting mechanism to perform the action. The connection method according to claim 11, wherein a resistance detecting means and a height measuring means for measuring the height of the fusible metal are connected between the welding surface of the fusible metal and the battery core; The height loss of the fusible metal after welding is not more than 0.2 mm. The connection method according to claim 11, wherein the connecting device further comprises: an output end of the resistance detecting device, an output end of the height measuring device, and an input end of the welding effect detecting module in the controller connection; The output end of the welding effect detecting module is connected with the input end of the welding effect determining module to make the welding effect determining module judge whether the welding is qualified according to the welding effect; the resistance detecting device detecting the internal resistance is not more than 0.5 mΩ is regarded as qualified. The connection method according to claim 11, wherein the connecting device further comprises a removal control module, and the input end of the removal control module is connected with the output end of the welding effect determination module to determine the result of the determination according to the welding effect determination module. The dismantling device is controlled to remove the unqualified cell welding surface, and the dismantling device is a robot; The controller further includes a cleaning and polishing control module, wherein the input end of the cleaning and polishing control module is connected with the output end of the removal control module, and the cleaning and polishing control module controls the cleaning and polishing device to polish the unqualified welding surface of the battery core for a preset time. Finishing sanding within 10s; The output of the cleaning and polishing control module is connected to the input end of the power conditioning module. After the cleaning and polishing control module is ground for a preset time, the power adjustment module controls the lifting mechanism to move the battery up to be welded with the fusible metal.

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