Unpacking device and unpacking method

Abstract

The invention discloses an unpacking device and an unpacking method, which are used for communicating a gas area of each single battery in a battery module with a hollow pipe fitting, and the single batteries are commercially available square lithium ion batteries. The unpacking device comprises a first sliding seat, a first traction rope, a second sliding seat, a second traction rope and a pricking needle assembly, when the unpacking device is used, the unpacking device is placed in the hollow pipe fitting, the unpacking device moves in the hollow pipe fitting by pulling the first traction rope, and the unpacking device can reach each single battery; and then a second pulling rope is pulled to drive a second sliding seat to slide to drive a pricking needle assembly to pierce an explosion venting film of the single battery, so that a through hole is formed in the single battery, and unpacking of each single battery is realized. The unpacking device unpacks each single battery in sequence, so that the unpacking reliability is high, and the unpacking efficiency is relatively high.

Description

Technical Field

[0001] The present invention belongs to the field of batteries, and particularly relates to an unpacking device and an unpacking method. Background Art

[0002] During the operation of a battery module, the electrolyte inside each single battery is prone to decomposition to generate gas. The gas accumulates inside the single battery, resulting in an increase in its internal pressure, and a series of problems will occur. Due to the differences in each single battery, the amount of gas generated in each single battery is also different. When the gas production of a certain single battery is too large and the internal pressure is too high, it may cause the electrode to deform, increase the risk of internal short circuit in the battery core, and also cause the battery case to deform and shorten the cycle life of the battery. More seriously, it may cause the single battery to catch fire or explode.

[0003] To solve the above problems, a related technology proposes a battery module, as Figure 1 described, the battery module 01 includes a hollow pipe fitting 02 and a plurality of single batteries 03; the inner cavity of the single battery 03 includes a gas area located above and an electrolyte area located below; the gas areas of the single batteries 03 are connected through the hollow pipe fitting 02, so that each single battery 03 is in a gas equilibrium state, reducing the problems caused by excessive gas production in a certain single battery.

[0004] When manufacturing the battery module 01, it is necessary to unpack each single battery so that the upper cover of the single battery forms a through hole for communicating with the hollow pipe fitting 02. How to achieve reliable and efficient unpacking of each single battery in the battery module is a problem that needs to be solved urgently at present. Summary of the Invention

[0005] In order to reliably and efficiently unpack the single batteries in the battery module, the present invention provides an unpacking device on the one hand.

[0006] The unpacking device is used to connect the gas areas of the single batteries in the battery module with the hollow pipe fitting. The single battery is a commercially available square lithium-ion battery. The unpacking device includes a first sliding seat, a first traction rope, a second sliding seat, a second traction rope, and a needle assembly;

[0007] The first sliding seat is a hollow U-shaped structure. A through hole is provided at the bottom of the first sliding seat, and first traction ropes are respectively provided at both ends of the first sliding seat. By respectively pulling the first traction ropes at both ends, the first sliding seat slides within the hollow pipe fitting of the battery module; the second sliding seat is slidably installed on the first sliding seat, and second traction ropes are respectively provided at both ends of the second sliding seat. By respectively pulling the second traction ropes at both ends, the second sliding seat slides on the first sliding seat; a cam surface is provided on the bottom surface of the second sliding seat; the needle assembly includes a fixed cylinder, a spring, and a needle; the fixed cylinder is fixedly installed within the first sliding seat, the needle is disposed on the fixed cylinder, and a spring is sleeved outside the portion of the needle located within the fixed cylinder; under the sliding action of the second sliding seat, the cam surface drives the needle to move towards the explosion vent film of the single battery and pierce the explosion vent film.

[0008] The present invention is composed of a first sliding seat, first traction ropes, a second sliding seat, second traction ropes, and a needle assembly. During use, it is placed within the hollow pipe fitting. By pulling the first traction ropes, the unpacking device can be moved within the hollow pipe fitting to reach each single battery. Then, by pulling the second traction ropes to drive the second sliding seat to slide, the needle assembly is driven to pierce the explosion vent film of the single battery, forming a through hole in the single battery, thereby realizing the unpacking of each single battery. This unpacking device unpacks each single battery in sequence, so the reliability of unpacking is high, and the unpacking efficiency is relatively high.

[0009] Further, the above-mentioned cam surface includes two arc-shaped recessed portions and an arc-shaped protruding portion provided between the two arc-shaped recessed portions. Among them, when the upper end portion of the needle cooperates with the arc-shaped recessed portion, the lower end of the needle is far from the explosion vent film of the single battery. When the upper end portion of the needle cooperates with the arc-shaped protruding portion, the lower end of the needle pierces the explosion vent film of the single battery. The design purpose of the two arc-shaped recessed portions is to facilitate the smooth reset of the needle after piercing the explosion vent film.

[0010] Further, sliding rods are provided on two mutually parallel side walls of the second sliding seat, and sliding grooves cooperating with the sliding rods are provided on the corresponding two side walls of the first sliding seat, and the length of the sliding groove is greater than or equal to the distance between the centers of the two arc-shaped recessed portions. The sliding connection mode of the first sliding seat and the second sliding seat through the sliding groove and the sliding rod has a simple and compact structure.

[0011] Further, in order to facilitate the connection between the first traction ropes and the first sliding seat and the connection between the second traction ropes and the second sliding seat, threading holes are provided at both ends of the first sliding seat and the second sliding seat.

[0012] Further, the first traction ropes and the second traction ropes are both made of flexible inextensible ropes.

[0013] Further, in order to improve the accuracy of the unpacking device moving on each single battery, scale marks are provided on the first traction rope. The distance between each two scale marks is a mark span, and a mark span is the distance between the centers of the explosion vent films of two adjacent single batteries on the large-capacity battery.

[0014] Further, in order to accurately identify the first traction rope and the second traction rope and reduce or even avoid misoperation, the first traction rope and the second traction rope are of different colors.

[0015] Further, in order to make the unpacking device hardly deviate when moving in the hollow pipe fitting, the outer dimension of the first sliding seat is adapted to the inner cavity dimension of the hollow pipe fitting.

[0016] Another aspect of the present invention provides an unpacking method using the above unpacking device, including the following steps:

[0017] Step 1: Install the unpacking device in the hollow pipe fitting, so that the unpacking device reaches the single battery at the head or the tail, and the puncturing needle is aligned with the explosion vent film of the single battery. It is necessary to ensure that the two first traction ropes and the two second traction ropes respectively extend out of both ends of the hollow pipe fitting; a first through hole for installing and removing the unpacking device is provided in the hollow pipe fitting directly above the single battery at the head or the tail, and second through holes are provided at both ends of the hollow pipe fitting;

[0018] Step 2: Fix one end of the first traction rope and pull the second traction rope at the other end. The second sliding seat slides on the first sliding seat, and the second sliding seat drives the puncturing needle to move towards the explosion vent film of the single battery at the head or the tail and pierce the explosion vent film. Then, under the action of the spring, the puncturing needle resets;

[0019] Step 3: Pull the first traction rope to move a mark span so that the unpacking device reaches the next single battery, and ensure that the puncturing needle is aligned with the explosion vent film of the single battery; fix one side of the first traction rope and pull the second traction rope at the other end. The second sliding seat slides on the first sliding seat, and the second sliding seat drives the puncturing needle to move towards the explosion vent film of the single battery at the head or the tail and pierce the explosion vent film;

[0020] Step 4: Repeat Step 3 to pierce the explosion vent films of the remaining single batteries;

[0021] Step 5: Take out the unpacking device from the hollow pipe fitting, and then seal the first through hole and the second through holes.

[0022] Further, the first through hole is sealed by welding a plug, and both of the two second through holes are sealed by welding a plug, or one of the second through holes is sealed by a rupture disc and the other second through hole is sealed by welding a plug. Description of the Drawings

[0023] Figure 1Schematic three-dimensional view of a battery module with a hollow pipe fitting;

[0024] Figure 2 Cross-sectional view of the unpacking device installed inside the hollow pipe fitting;

[0025] Figure 3 Three-dimensional view of the unpacking device;

[0026] Figure 4 Cross-sectional view of the unpacking device;

[0027] Figure 5 Structural diagram of the first sliding seat;

[0028] Figure 6 Structural diagram of the second sliding seat.

[0029] Reference numerals are as follows:

[0030] 01 - Battery module, 02 - Hollow pipe fitting, 03 - Single battery;

[0031] 1 - First sliding seat, 11 - Left end plate, 12 - Right end plate, 13 - Front side plate, 14 - Rear side plate, 15 - Bottom plate, 16 - Through hole, 17 - Slide groove, 2 - First towing rope, 3 - Second sliding seat, 31 - Slide bar, 4 - Second towing rope, 5 - Needle assembly, 51 - Fixed cylinder, 52 - Spring, 53 - Needle, 6 - Cam surface, 61 - Arc-shaped recessed part, 62 - Arc-shaped protruding part, 7 - Threading hole. Detailed implementation

[0032] Next, the technical solutions in the embodiments will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments, rather than all of the embodiments. Based on the following embodiments, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0033] At the same time, it should be noted that the orientation or positional relationship indicated by terms such as "top, bottom, inner, and outer" in the text is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of simplified description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation on the technical solution. In addition, the terms "first, second, or third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0034] Unless otherwise clearly specified and defined in the present invention, the terms "installation, connection, and coupling" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection: It may also be a mechanical connection, an electrical connection, or a direct connection, and may also be indirectly connected through an intermediate medium, or may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention may be understood according to specific circumstances.

[0035] The main purpose of the unpacking device of the present invention is to unpack each single battery in the battery module, so that the gas areas in the inner cavities of each single battery are connected through the hollow pipe fittings. In the current related technologies, customized single batteries with sealed unpacking parts are assembled into a battery module. The sealed unpacking part needs to ensure the sealing of the single battery before the single battery forms a battery module. When forming a battery module, the sealed unpacking parts on each single battery need to be opened. The sealed unpacking parts adopted by the existing single batteries are pull-ring type sealing mechanisms or sealing films that can be dissolved in the electrolyte.

[0036] During the actual production and trial process, it is found that when single batteries with pull-ring type sealing mechanisms form a battery module, when using a traction rope to open the pull-ring type sealing mechanism, the pull-ring type sealing mechanisms of some single batteries may not be opened, resulting in a poor unpacking success rate of the single batteries.

[0037] When single batteries with dissolving type sealing films form a battery module, the time required to dissolve the sealing film with the electrolyte is relatively long, resulting in a low production efficiency of the battery module.

[0038] To solve the problems existing in the related technologies, this embodiment provides an unpacking device, as Figure 2 shown, including a first sliding seat 1, a first traction rope 2, a second sliding seat 3, a second traction rope 4, and a needle assembly 5;

[0039] The first sliding seat 1 is a hollow U-shaped structure, as Figure 2 , Figure 3 and Figure 5 shown. Specifically, in this embodiment, the first sliding seat 1 includes a left end plate 11, a right end plate 12, a front side plate 13, a rear side plate 14, and a bottom plate 15. A through hole 16 is provided at the bottom of the first sliding seat 1 (that is, the bottom plate is provided with a through hole). At both ends of the first sliding seat 1 (that is, the left end plate 11 and the right end plate 12), first traction ropes 2 are respectively provided (for the convenience of understanding, the first traction rope connected to the left end plate is defined as the first traction rope A, and the first traction rope connected to the right end plate is defined as the first traction rope B). By respectively pulling the first traction ropes 2 at both ends, the first sliding seat 1 slides in the hollow pipe fitting of the battery module; that is to say, by pulling the first traction rope 2, the unpacking device can reach each single battery that needs to be unpacked;

[0040] As Figure 2 , Figure 3and Figure 6 As shown in Figure 6 , the second sliding seat 3 is slidably mounted on the first sliding seat 1, and second traction ropes 4 are respectively provided at both ends (i.e., the left end and the right end) of the second sliding seat 3 (for the sake of easy understanding, herein, the second traction rope on the same side as the first traction rope A is defined as the second traction rope C, and the second traction rope on the same side as the first traction rope B is defined as the second traction rope D). By respectively pulling the second traction ropes 4 at both ends, the second sliding seat 3 slides on the first sliding seat 1; a cam surface 6 is provided on the bottom surface of the second sliding seat 3;

[0041] As Figure 4 shown in Figure 4 , the needle assembly 5 includes a fixed cylinder 51, a spring 52 and a needle 53; the fixed cylinder 51 is fixedly installed in the first sliding seat 1 and corresponds to the through hole 16 of the bottom plate 15. The needle 53 is arranged on the fixed cylinder 51, and a spring 52 is sleeved outside the part of the needle 53 located inside the fixed cylinder 51;

[0042] Under the sliding action of the second sliding seat 3, the cam surface 6 drives the needle 53 to move towards the explosion vent film of the single battery, pass through the through hole 16 and pierce the explosion vent film.

[0043] Specifically, as Figure 6 shown in Figure 6 , in this embodiment, the second sliding seat 3 is a strip-shaped structure, and the cam surface 6 on its bottom surface includes two arc-shaped recessed parts 61 (for the sake of easy understanding, herein, the arc-shaped recessed part close to the second traction rope C is defined as the arc-shaped recessed part E, and the arc-shaped recessed part close to the second traction rope D is defined as the arc-shaped recessed part F) and an arc-shaped protruding part 62; when the upper end of the needle cooperates with the arc-shaped recessed part E, the spring 52 is in a natural state, and the lower end of the needle 53 is far from the explosion vent film of the single battery. By pulling the second traction rope C, the second sliding seat 3 slides on the first sliding seat 1, and the upper end of the needle 53 cooperates with the arc-shaped protruding part 62, and the lower end of the needle 53 starts to move downward and pierce the explosion vent film of the single battery. At this time, the spring 52 is in a compressed state. By continuing to pull the second traction rope C, under the restoring force of the spring 52, the upper end of the needle 53 cooperates with the arc-shaped recessed part E; the design purpose of the two arc-shaped recessed parts is to facilitate the smooth reset of the needle after piercing the explosion vent film.

[0044] In this embodiment, since the space inside the hollow pipe fitting is small, in order to make the structure of the unpacking device compact, sliding grooves 17 are provided on the front side plate 13 and the rear side plate 14 of the first sliding seat 1, and sliding rods 31 cooperating with the sliding grooves 17 are provided on the two side walls of the second sliding seat 3.

[0045] In this embodiment, in order to facilitate the connection between the first towing rope 2 and the first sliding seat 1 and the connection between the second towing rope 4 and the second sliding seat 3, threading holes 7 are provided at both ends (i.e., the left end and the right end) of the first sliding seat 1 and the second sliding seat 3. At the same time, in order to ensure that the first towing rope 2 and the second towing rope 4 do not undergo telescopic deformation during pulling, the first towing rope 2 and the second towing rope 4 are both made of flexible non-telescopic ropes. For example, common flexible non-telescopic ropes include household steel wire ropes, fiberglass ropes, high-strength fiber ropes, etc.

[0046] In this embodiment, in order to ensure that the needle 53 of the unpacking device can be aligned with the explosion vent film of the single battery to be unpacked each time the first towing rope 2 is pulled, a scale mark is provided on the first towing rope 2, and the distance between each scale mark is a mark span, and a mark span is the distance between the centers of two adjacent single battery explosion vent films on a large-capacity battery.

[0047] Since the first towing rope 2 and the second towing rope 4 perform different tasks, in order to accurately identify the first towing rope and the second towing rope during operation and reduce or even avoid misoperation, in this embodiment, the first towing rope and the second towing rope are of different colors.

[0048] In order to ensure that the unpacking device hardly deviates when moving in the hollow pipe fitting, in this embodiment, the outer dimension of the first sliding seat 1 is adapted to the inner cavity dimension of the hollow pipe fitting. Specifically, that is, the height dimension of the first sliding seat 1 is basically the same as the height dimension of the hollow pipe fitting, and the width dimension of the first sliding seat 1 is basically the same as the width dimension of the hollow pipe fitting.

[0049] Based on the above description of the structure of the unpacking device, when using this unpacking tool, compared with the related art, it has the following advantages:

[0050] 1. The unpacking tool of the present invention uses a puncturing method to unpack the single battery, and can directly use commercially available square batteries to form a battery module with a gas balance system (puncturing the explosion vent film of the commercially available square battery). Compared with the existing battery module with a gas balance system, it is not necessary to customize single batteries with unpacking seals, nor to modify the single batteries, the scope of application is not limited, and the cost of the battery module is lower.

[0051] 2. The unpacking tool of the present invention uses a puncturing method to unpack the single battery. Compared with the unpacking method of dissolving the sealing film with electrolyte, the unpacking speed is faster and the production efficiency of the battery module is higher.

[0052] 3. The unpacking tool of the present invention uses a puncturing method to unpack the single battery. Compared with the pull-ring type sealing mechanism, the unpacking accuracy and success rate are higher.

[0053] 4. The unpacking tool of the present invention can be reused.

[0054] The specific usage method of the unpacking device in this embodiment is as follows:

[0055] It should be noted that: a first through hole and two second through holes are provided on the hollow pipe fitting 02 of the battery module 01; among them, the opening position of the first through hole is directly above a certain single battery, and is used for installing and removing the unpacking device; the two second through holes are respectively located at the head and tail ends of the hollow pipe fitting 02;

[0056] See Figures 2 to 6 , in this embodiment, the head single battery is unpacked first, and the specific implementation process is as follows:

[0057] Step 1: Assemble the unpacking device and move it above the head single battery;

[0058] First, connect the first sliding seat 1, the second sliding seat 3, and the needle assembly 5 into an integral part;

[0059] Then, respectively insert the first towing rope A and the second towing rope C into the hollow pipe fitting 02 from one side of a second through hole of the hollow pipe fitting 02, and draw out part of the first towing rope A and the second towing rope C from the first through hole. After that, pass the drawn-out part of the first towing rope A through the threading hole 7 on the left side of the first sliding seat 1 and fix it, and pass the second towing rope C through the threading hole 7 on the left side of the second sliding seat 3 and fix it;

[0060] Next, respectively insert the first towing rope B and the second towing rope D into the hollow pipe fitting 02 from the other side of the second through hole of the hollow pipe fitting 02, and draw out part of the first towing rope B and the second towing rope D from the first through hole. After that, pass the drawn-out part of the first towing rope B through the threading hole 7 on the right side of the first sliding seat 1 and fix it, and pass the second towing rope D through the threading hole 7 on the right side of the second sliding seat 3 and fix it;

[0061] Finally, put the unpacking device into the hollow pipe fitting 02 from the first through hole, and by pulling the first towing rope A, move the unpacking device to the position above the head single battery in the battery module, and ensure that the needle of the unpacking device is aligned with the explosion vent film of the single battery;

[0062] Step 2: Unpack the head single battery

[0063] If in the initial state, the upper end of the needle 53 is located in the arc-shaped recess E, then fix the part of the first towing rope A outside the hollow pipe fitting, and at the same time pull the part of the second towing rope D outside the hollow pipe fitting. The second sliding seat 3 slides on the first sliding seat 1, and the second sliding seat 3 drives the needle to move towards the explosion vent film of the head single battery and pierce the explosion vent film. Continue to pull the second towing rope D, and the needle 53 rebounds to the arc-shaped recess F under the action of the spring 52, thus completing the unpacking of the head single battery;

[0064] If initially, the upper end of the lancet 53 is located within the arc-shaped recess F, fix the portion of the first traction rope B outside the hollow pipe fitting, and at the same time pull the second traction rope C. The second sliding seat 3 slides on the first sliding seat 1. The second sliding seat 3 drives the lancet 53 to move towards the explosion-proof film of the first unit cell and pierce the explosion-proof film. Continue to pull the second traction rope C, and the lancet 53 rebounds to the arc-shaped recess E under the action of the spring 52, thereby completing the unpacking of the first unit cell;

[0065] Step 3: Unpacking of the remaining unit cells

[0066] Step 3.1: Pull the first traction rope B to move a marking span so that the unpacking device reaches the second unit cell, ensuring that the lancet 53 is aligned with the explosion-proof film of this unit cell; fix the first traction rope B, pull the second traction rope C, the second sliding seat 3 slides on the first sliding seat 1, and the second sliding seat 3 drives the lancet 53 to move towards the explosion-proof film of this unit cell and pierce the explosion-proof film. Continue to pull the second traction rope C, and the lancet 53 rebounds to the arc-shaped recess F under the action of the spring 52, thereby completing the unpacking of the second unit cell;

[0067] Step 3.2: Pull the first traction rope B again to move a marking span so that the unpacking device reaches the third unit cell, ensuring that the lancet is aligned with the explosion-proof film of this unit cell; fix the first traction rope A, pull the second traction rope D, the second sliding seat 3 slides on the first sliding seat 1, and the second sliding seat 3 drives the lancet 53 to move towards the explosion-proof film of this unit cell and pierce the explosion-proof film. Continue to pull the second traction rope D, and the lancet 53 rebounds to the arc-shaped recess E under the action of the spring 52, thereby completing the unpacking of the third unit cell;

[0068] Step 4: Repeat steps 3.2 and 3.3 to complete the unpacking of all unit cells;

[0069] Step 5: Remove the unpacking device from the first through-hole of the hollow pipe fitting, and then seal the first through-hole and the second through-holes;

[0070] The specific sealing methods for the first through-hole and the two second through-holes are as follows:

[0071] (1) The first through-hole is sealed by welding a plug or a rubber plug, and the two second through-holes are both sealed by welding a plug; at this time, the hollow pipe fitting of the battery module serves as a gas balance channel to make the air pressure in the inner cavities of each unit cell consistent. At the same time, it can also serve as an air pressure buffer storage cavity, further reducing the thermal runaway accident caused by excessive air pressure in the unit cell.

[0072] (2) The first through-hole is sealed by welding a blanking piece or a rubber plug, one of the second through-holes is sealed by a rupture disc, and the other second through-hole is sealed by welding a blanking piece. At this time, in addition to the function in (1), the hollow pipe fitting can also serve as a venting channel. In some extreme cases, when a single battery undergoes thermal runaway, the hot gas generated by the thermal runaway can be vented through the rupture disc.

[0073] (3) The first through-hole is sealed by welding a blanking piece or a rubber plug, one of the second through-holes is sealed by an exhaust valve, and the other second through-hole is sealed by welding a blanking piece. At this time, in addition to the function in (1), the hollow pipe fitting can also serve as an exhaust channel. By regularly opening the exhaust valve, the gas stored in the hollow pipe fitting can be discharged.

Claims

1. An unpacking device is used to connect the gas areas of individual batteries in a battery module to a hollow pipe fitting. The individual batteries are commercially available square lithium-ion batteries. It is characterized in that the unpacking device includes a first sliding seat, a first towing rope, a second sliding seat, a second towing rope, and a needle assembly. The first sliding seat is a hollow U-shaped structure. A through hole is provided at the bottom of the first sliding seat. First towing ropes are respectively provided at both ends of the first sliding seat. By pulling the first towing ropes at both ends respectively, the first sliding seat slides within the hollow pipe fitting of the battery module. The second sliding seat is slidably mounted on the first sliding seat. Second towing ropes are respectively provided at both ends of the second sliding seat. By pulling the second towing ropes at both ends respectively, the second sliding seat slides on the first sliding seat. A cam surface is provided on the bottom surface of the second sliding seat. The needle assembly includes a fixed cylinder, a spring, and a needle. The fixed cylinder is fixedly installed within the first sliding seat. The needle is provided on the fixed cylinder. A spring is sleeved outside the part of the needle located within the fixed cylinder. Under the sliding action of the second sliding seat, the cam surface drives the needle to move towards the explosion vent film of the individual battery, pierce through the through hole, and then puncture the explosion vent film.

2. An unpacking device according to claim 1, It is characterized in that the cam surface includes two arc-shaped recessed parts and an arc-shaped protruding part provided between the two arc-shaped recessed parts.

3. An unpacking device according to claim 2, It is characterized in that slide bars are provided on two mutually parallel side walls of the second sliding seat, and chutes cooperating with the slide bars are provided on the corresponding two side walls of the first sliding seat, and the length of the chute is greater than or equal to the distance between the centers of the two arc-shaped recessed parts.

4. An unpacking device according to claim 3, It is characterized in that threading holes are provided at both ends of the first sliding seat and the second sliding seat.

5. An unpacking device according to claim 4, It is characterized in that both the first towing rope and the second towing rope are made of flexible non-stretchable ropes.

6. An unpacking device according to claim 5, It is characterized in that scale markings are provided on the first towing rope. The distance between each two scale markings is a marking span. A marking span is the distance between the centers of the explosion vent films of two adjacent individual batteries on a large-capacity battery.

7. An unpacking device according to claim 6, It is characterized in that the first towing rope and the second towing rope are of different colors.

8. An unpacking device according to claim 7, It is characterized in that the outer dimensions of the first sliding seat are adapted to the inner cavity dimensions of the hollow pipe fitting.

9. An unpacking method, It is characterized in that using the unpacking device according to claim 8, the unpacking method includes the following steps: Step 1: Install the unpacking device within the hollow pipe fitting, so that the unpacking device reaches the individual battery at the head or tail, and the needle is aligned with the explosion vent film of the individual battery. It is necessary to ensure that the two first towing ropes and the two second towing ropes respectively extend out of both ends of the hollow pipe fitting. The hollow pipe fitting is provided with a first through hole for installing and removing the unpacking device directly above the individual battery at the head or tail, and second through holes are provided at both ends of the hollow pipe fitting. Step 2: Fix one end of the first traction rope and pull the second traction rope at the other end. The second sliding seat slides on the first sliding seat. The second sliding seat drives the puncture needle to move towards the explosion vent film of the head or tail single cell and puncture the explosion vent film. Then, under the action of the spring, the puncture needle resets. Step 3: Pull the first traction rope to move a marking span so that the unpacking device reaches the next single cell, ensuring that the puncture needle is aligned with the explosion vent film of this single cell; Fix one side of the first traction rope and pull the second traction rope at the other end. The second sliding seat slides on the first sliding seat. The second sliding seat drives the puncture needle to move towards the explosion vent film of the head or tail single cell and puncture the explosion vent film. Step 4: Repeat Step 3 to puncture the explosion vent films of the remaining single cells. Step 5: Take out the unpacking device from the hollow pipe fitting, and then seal the first through hole and the second through hole.

10. The unpacking method according to claim 9, wherein, the first through hole is sealed by welding a plug piece, both of the two second through holes are sealed by welding a plug piece, or one of the second through holes is sealed by an explosion vent valve and the other second through hole is sealed by welding a plug piece.

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