Device and method for recovering recess of square battery shell

Abstract

The invention discloses a recovery device and method for a recess of a square battery shell. The recovery device comprises a vacuum cover, a battery large surface pressing mechanism, a battery side surface pressing mechanism, a battery top pressing mechanism and a pin inserting mechanism, wherein a hole is formed in the bottom of the vacuum cover; a top pressing plate of the battery top pressing mechanism is provided with a sealing ring for sealing an anti-explosion valve on a battery cover plate, and a reserved opening corresponding to a battery top liquid injection hole and a pole; the battery large surface pressing mechanism and the battery side surface pressing mechanism respectively comprise a pair of large surface pressing plates and a pair of side surface pressing plates; the two large surfaces and the two side surfaces of the battery are respectively pressed; penetrating through holes are formed in the large surface pressing plate and the side surface pressing plate; and the pin inserting mechanism is used for inserting a pipe body of the top pressing plate into the liquid injection hole after the top pressing plate is pressed on the battery cover plate, tightly matching the pipe body with the inner wall of the liquid injection hole, pumping the interior of the battery to be empty, and then injecting shielding gas. The problem that the surface of the square battery shell is concave inwards can be effectively solved.

Description

Technical Field

[0001] This invention relates to the field of battery casing surface treatment technology, and in particular to a device and method for restoring dents in a square battery casing. Background Technology

[0002] The square aluminum-cased battery is made of ternary aluminum alloy, a relatively soft material that is prone to deformation when used as a battery casing. This often manifests as significant indentation on the sides or large surfaces of the battery. Multiple factors, such as gas generation during formation, capacity testing, charging and discharging, electrode expansion, and vacuuming during electrolyte injection and insertion, can cause side or large surface indentations in square aluminum-cased batteries during manufacturing. These indentations directly affect the coating yield. If left uncontrolled, exceeding the coating machine's tolerance for indentation can lead to downtime and rework; in severe cases, it can result in customer complaints and damage to the cell's insulation.

[0003] A step-by-step analysis of the processes that cause large-area / side concavity in the production of square aluminum-cased batteries reveals that the vacuuming and leak testing of the injection chamber and the vacuuming and positive pressure circulation injection process during the electrolyte injection process cause concavity on the battery sides. During the formation and venting process, the battery is under negative pressure for a long time, which causes deformation of the aluminum casing, especially on the sides. When the battery is filled with helium pins, the vacuuming and helium return process under the restraint state further aggravates the degree of side concavity. After the battery is sealed, the capacity testing and high-temperature / room-temperature aging processes cause the expansion and contraction of the electrode assembly and the reduction of internal pressure due to gas production and consumption, which also aggravates the degree of concavity on the battery surface. Since there are large gaps in the electrode assembly filling on the side of the battery, the concavity caused by this process is particularly prominent on the side. Taking a 57x200x218mm battery as an example, the concavity on the side before the battery is sealed can generally reach about 0.5mm. At this stage, the aluminum shell has already undergone irreversible plastic deformation. The side concavity after the battery is sealed will only be aggravated to this extent. Therefore, it is particularly important to thoroughly improve the problem of battery concavity before sealing.

[0004] Currently, common methods to improve the indentation of square aluminum-cased batteries include full-constraint capacity testing and positive pressure return via a pin insertion machine, as well as isobaric liquid injection, but the effects are not significant. Defects in the coating caused by indentation usually account for about 20% of the overall appearance defects.

[0005] Chinese patent CN118841619A discloses a battery nitrogen-filling shaping device and method. This invention patent inflates the battery by filling it with helium gas through the battery injection hole, and then uses clamps that fit together to press it down to restrict the shape of the battery, causing the dented parts to bulge out, thereby improving the appearance of the battery. This patent has two defects: (1) it does not consider that excessive gas pressure may cause the explosion-proof valve to break, and that insufficient gas pressure may not effectively improve the dented situation; (2) the liquid level inside the finished battery casing is high and almost level with the injection hole. Directly applying positive pressure results in inconsistent force from top to bottom inside the battery, which may cause the upper part of the battery to be improved more than the lower part, resulting in poor overall consistency of improvement.

[0006] Chinese patent CN116864814A discloses a method for improving the surface depression of a battery cell. This invention involves sequentially performing laser top cover welding airtightness testing, primary liquid injection, formation, secondary liquid injection, and sealing nail welding processes on the assembled battery cell to be welded to the top cover, while maintaining the same internal and external pressure in each process to ensure a smooth surface and prevent battery depression. The patent maintains the same internal and external air pressure by connecting a vacuum suction pipe to a washing device that adsorbs the air pores onto the large surface of the battery. The patent has two drawbacks: (1) The large surface of the battery is smooth, but the flatness of different parts varies, making it difficult to ensure that the air pores can be firmly adsorbed onto the large surface of the battery; (2) During the vacuum suction process, both the large surface and the sides of the battery are subjected to force, and even if the vacuum suction cup can firmly adsorb the large surface, the pressure difference between the inside and outside of the battery can still cause a large degree of depression on the sides.

[0007] Chinese patent CN115207580A discloses a method for repairing side dents in battery casings and a battery fixing device. This invention increases the outward expansion of the dented area in the battery casing into the recessed space within the battery fixing device during positive pressure injection. Then, negative pressure is applied to cause a certain degree of retraction, repairing the dent. The main drawback of this patent is the difficulty in controlling the degree of dent formation through positive and negative pressure injection. Excessive positive pressure can cause the battery to bulge and undergo plastic deformation that is difficult to recover from. Excessive negative pressure can cause indentation on both the side and the main surface of the battery. This method is poorly considered and has limited practicality. Summary of the Invention

[0008] The purpose of this invention is to solve the problem of concave sides / large surfaces of square aluminum-cased batteries, and to provide a device and method for restoring the concavity of square battery casings to improve the concavity problem. The method or technology of this invention can reshape and repair each surface of the square aluminum-cased battery, restoring the battery surface to a flat state and restoring the concave sides / large surfaces to a nearly completely flat state, effectively solving the problem of surface concavity in square battery casings.

[0009] One objective of this invention is to provide a device for restoring a dented square battery casing, comprising a vacuum shroud with a bottom opening, and a battery large-face pressing mechanism, a battery side pressing mechanism, a battery top pressing mechanism, and a pin insertion mechanism arranged within the vacuum shroud; the top pressing plate of the battery top pressing mechanism has a sealing ring for sealing the explosion-proof valve on the battery cover, and a reserved opening corresponding to the battery top injection hole and terminal post; the battery large-face pressing mechanism and the battery side pressing mechanism each include a pair of large-face pressing plates and a pair of side pressing plates, respectively pressing the two large faces and two side faces of the battery; the large-face pressing plates and the side pressing plates have through holes; the pin insertion mechanism is used to move downward after the top pressing plate presses against the battery cover, insert its pin tube into the injection hole, tightly fit with the inner wall of the injection hole, evacuate the battery interior, and then inject protective gas.

[0010] Preferably, the bottom of the vacuum hood is provided with a loading and unloading platform, which, when raised, seals with the loading and unloading opening at the bottom of the vacuum hood.

[0011] Preferably, the vacuum hood has an air pipe interface for connecting to a vacuum pump to create negative pressure inside the vacuum hood.

[0012] Preferably, the battery large-area pressing mechanism, the battery side pressing mechanism, and the battery top pressing mechanism are each driven by a linear drive module, and the linear drive module is connected and fixed to the inner wall of the protective cover through a fixing plate.

[0013] Preferably, the insertion mechanism has a pre-reserved air connection port for connecting to an external protective air pipeline.

[0014] Preferably, after the top pressure plate, the large surface pressure plate, and the side pressure plate are moved to press against the battery position and connected to each other on the sides, the space formed on the inner surface of the cavity is adapted to the size of the battery to be processed.

[0015] Another object of the present invention is to provide a method for restoring a dent in a square battery casing, implemented based on the device for restoring a dent in a square battery casing, comprising the following steps:

[0016] The battery to be processed is placed inside the protective cover through the bottom opening of the protective cover at the loading and unloading station, so that the loading and unloading station is sealed to the bottom opening.

[0017] The battery large surface clamping mechanism, battery side clamping mechanism and battery top clamping mechanism are activated in sequence to clamp the large surface, side and top of the battery in sequence, seal the battery explosion-proof valve and complete the battery restraint.

[0018] The insertion mechanism is pressed tightly onto the battery filling hole, and the battery is evacuated through the insertion mechanism. After the evacuation operation is completed, protective gas is injected into the battery through the insertion mechanism. The protective gas is kept to flow freely in its channel under external pressure changes, so that the internal gas pressure of the battery is at normal pressure or positive pressure.

[0019] A gradient vacuum is applied to the inside of the vacuum chamber, and the pressure difference between the inner and outer surfaces of the battery restores the surface depressions of the battery casing to a flat state.

[0020] Preferably, after the recess in the battery casing is restored to a flat state, the insertion mechanism seals the injection hole with adhesive pins.

[0021] Preferably, the vacuum chamber is subjected to gradient evacuation at least three times, with pressure maintained for a period of time after each evacuation; the vacuum level inside the vacuum chamber gradually increases during the three evacuations.

[0022] Preferably, during the first vacuuming, the internal pressure of the vacuum chamber does not exceed 30 kPa; during the second vacuuming, the internal pressure of the vacuum chamber does not exceed 1000 Pa; and during the third vacuuming, the internal pressure of the vacuum chamber does not exceed 100 Pa.

[0023] The device and method for restoring the dented casing of a square battery of the present invention can create a pressure difference between the inside and outside of the battery by gradually increasing the vacuum of the external environment of the battery in stages, while simultaneously decreasing the vacuum and breaking the vacuum inside the battery to normal pressure or slightly positive pressure. This flattens and straightens the battery that has been dented on a large surface or side, thus achieving appearance repair and reshaping of the battery. Clamping and limiting fixtures are used to constrain the various surfaces of the battery to prevent changes in the battery's appearance dimensions. At the same time, the pressure difference generated by the decrease in internal pressure due to the increase in battery volume during the vacuum breaking and flattening process allows helium to automatically return into the battery, achieving the helium return function of an equivalent insertion device. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the pressing principle of the recovery device for the dented square battery casing of the present invention.

[0025] Figure 2 This is a schematic diagram illustrating the structural principle of the device for restoring a dented square battery casing according to the present invention. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0027] An exemplary embodiment of this application provides a device for restoring dents in a square battery casing. This device addresses the root causes of dents in square aluminum-cased batteries by specifically improving the dent condition. The main improvement occurs before battery sealing, specifically during the helium-filling and pinning process. The battery is positioned by clamping and restraining its large, side, and top surfaces during the helium-filling and pinning process, and then sealed with adhesive pins after vacuuming.

[0028] See Figures 1 to 2 As shown, an exemplary embodiment of this application provides a device for restoring a dented square battery casing, including a vacuum shroud 8 with a bottom opening, and a battery large-surface pressing mechanism, a battery side pressing mechanism, a battery top pressing mechanism, and a pinning mechanism 15 arranged within the vacuum shroud 8; the top plate 10 of the battery top pressing mechanism has a sealing ring 11 for sealing the explosion-proof valve 14 on the battery cover, and a reserved opening 13 corresponding to the battery top injection hole 12 and the positive and negative terminals 16; the battery large-surface pressing mechanism and the battery side pressing mechanism each include a pair of large-surface pressing plates 5 and a pair of side pressing plates 6, which respectively press the two large surfaces and two sides of the battery; the large-surface pressing plates and the side pressing plates have through holes, such as Figure 2 The small circles shown can be multiple and arranged in a rectangular shape; the pin insertion mechanism 15 is used to move downward after the top pressure plate 10 presses against the battery cover plate, insert its pin tube into the liquid injection hole, fit tightly with the inner wall of the liquid injection hole, evacuate the inside of the battery, and then inject protective gas.

[0029] In this application, through holes are made on both the large-area pressure plate and the side pressure plate to facilitate the smooth flow of gas in the cavity formed between the battery depression and the clamping mechanism during the vacuuming process. This prevents the formation of a sealed cavity between the battery large-area or side and the clamping mechanism, which would affect the effect of the pressure difference created by the vacuum hood on leveling and straightening the battery surface depression.

[0030] In the embodiments of this application, the clamping mechanism serves to restrain and position the sides and large surfaces of the battery, preventing deformation of the battery structure and dimensions caused by pressure differences between the inside and outside of the battery. Specifically, the top pressure plate 10, directly opposite the sealing ring 11 on the explosion-proof valve 14 of the battery cover, presses down onto the battery cover along its movement trajectory, tightly fitting with the explosion-proof valve to prevent gas from entering or overflowing, thus preventing the explosion-proof valve from rupturing due to localized pressure differences during the vacuuming process of the vacuum chamber 8. A pre-reserved opening 13 is provided on the top pressure plate 10 opposite the liquid injection hole 12, facilitating tight contact between the insertion mechanism 15 and the battery liquid injection hole. Pre-reserved openings 17 at the positions of the positive and negative terminals 16 allow the top pressing mechanism to form a completely fitted plane with the battery cover.

[0031] In this embodiment, the pin insertion mechanism 15, which is located above the injection hole 12, is inside the vacuum chamber 8 and fixed to the top of the vacuum chamber. It can be controlled by a servo motor to move in the vertical direction. When the top pressure plate 10 is pressed down, the pin insertion mechanism 15 is controlled to move and will descend to press tightly against the injection hole 12 to prevent gas leakage.

[0032] In this embodiment of the application, after the battery has completed all the indentation improvement actions, the plug structure 15 can perform a sealing plug treatment on the injection hole 12, and the battery is then sealed.

[0033] In some embodiments of this application, the bottom of the vacuum hood is provided with a loading and unloading platform 19. When the loading and unloading platform is raised, it seals with the loading and unloading opening at the bottom of the vacuum hood, thereby forming a sealed connection with the vacuum hood, which is beneficial for the vacuuming of the vacuum hood and the realization of the internal vacuum degree.

[0034] In some embodiments of this application, the vacuum shroud has an air pipe interface 9, preferably arranged on the bottom panel of the vacuum shroud, for connecting to a vacuum pump. By controlling the air pump to draw negative pressure inside the vacuum shroud, the entire cavity can be evacuated.

[0035] In some embodiments of this application, the battery large-area pressing mechanism, the battery side pressing mechanism, and the battery top pressing mechanism are each driven by a linear drive module. The linear drive module is connected and fixed to the inner wall of the protective cover 8 via its respective fixing plate. In some embodiments, the linear drive module can be a telescopic cylinder or a similar device; pressing and releasing the battery can be achieved by controlling the extension and retraction of the cylinder. The top pressing plate is connected to the front end of the drive rod of the telescopic cylinder, which is fixed to the top fixing plate 21. The top fixing plate 21 is fixed to the top of the vacuum cover. Similarly, the telescopic cylinders or similar devices of the large-area pressing plate and the side pressing plate are mounted on the side fixing plate 4, which is fixed to the bottom inner wall of the vacuum cover.

[0036] In some embodiments of this application, the pin insertion mechanism 15 has a pre-reserved gas connection port 20, which can be formed on the connecting seat of the pin insertion pipe of the pin insertion mechanism 15. Its gas outlet end is connected to the pin insertion pipe for connection to an external protective gas pipeline. The external protective gas pipeline is connected to a protective gas source to provide protective gas, such as helium.

[0037] In some embodiments of this application, after the top pressure plate, the large surface pressure plate, and the side pressure plates are moved to press against the battery position and connected to each other on the sides, the space formed on the inner surface of the cavity is adapted to the size of the battery to be processed. This arrangement helps to restrain the outside of the battery and prevent the outer surface of the battery from deforming when the air is evacuated.

[0038] An embodiment of this application also provides a method for restoring a dent in a square battery casing, implemented using the device for restoring a dent in a square battery casing, comprising the following steps:

[0039] The battery to be processed is placed inside the protective cover through the bottom opening of the protective cover at the loading and unloading station, so that the loading and unloading station is sealed to the bottom opening.

[0040] The battery large surface clamping mechanism, battery side clamping mechanism and battery top clamping mechanism are activated in sequence to clamp the large surface, side and top of the battery in sequence, seal the battery explosion-proof valve and complete the battery restraint.

[0041] The insertion mechanism is pressed tightly onto the battery filling hole, and the battery is evacuated through the insertion mechanism. After the evacuation operation is completed, protective gas is injected into the battery through the insertion mechanism, and the protective gas is allowed to flow freely in its channels under external pressure changes.

[0042] A gradient vacuum is applied to the inside of the vacuum chamber, and the pressure difference between the inner and outer surfaces of the battery restores the surface depressions of the battery casing to a flat state.

[0043] The entire vacuum cover uses a gradient vacuum method, which can greatly improve the effect of battery indentation improvement and avoid irreversible damage to the battery appearance caused by excessive instantaneous vacuum.

[0044] In some embodiments of this application, the vacuum chamber is subjected to gradient evacuation at least three times, with pressure maintained for a period after each evacuation; the vacuum level inside the vacuum chamber gradually increases during the three evacuations. Through this three-stage gradient evacuation method, a strong pressure difference can be formed between the vacuum chamber and the inside of the battery. Combined with the constraint clamping fixture limiting the battery size, the improved battery casing surface is nearly flat, and its dimensions remain unchanged.

[0045] In some embodiments of this application, during the first vacuuming, the internal pressure of the vacuum chamber does not exceed 30 kPa; during the second vacuuming, the internal pressure of the vacuum chamber does not exceed 1000 Pa; and during the third vacuuming, the internal pressure of the vacuum chamber does not exceed 100 Pa. Specifically, a gradient vacuuming method can be used.

[0046] The first vacuuming process takes 5-10 seconds, during which the pressure inside the vacuum chamber decreases from atmospheric pressure, not exceeding 30 kPa, and is held for 5 seconds. The purpose is to rapidly reduce the internal pressure to a low level. The second vacuuming process takes 10-15 seconds, during which the pressure inside the vacuum chamber continues to decrease from 30 kPa, not exceeding 1000 Pa, and is held for 10 seconds. The purpose is to flatten the dented battery casing using a higher negative pressure. The third vacuuming process takes 10-20 seconds, during which the pressure inside the vacuum chamber continues to decrease from 1000 Pa, not exceeding 100 Pa, and is held for 10-15 seconds. The purpose is to completely flatten the battery casing surface using an ultra-high vacuum. Specific time parameters, vacuum pressure parameters, and holding pressure parameters can be selected and determined within the above ranges.

[0047] The method for restoring the dented square battery casing of this application embodiment involves evacuating the external environment of the battery before the battery is sealed with pins to create a pressure difference between the inside and outside of the battery, thereby flattening and straightening the dented side / large surface of the battery. By using a gradient vacuum method, the effect of flattening and straightening the dented area on the battery surface is improved, and the rebound phenomenon caused by the incomplete release of metal stress is reduced.

[0048] The method for restoring the dented square battery casing of this application embodiment can effectively prevent deformation of the battery's appearance and size during the flattening process by using a clamping mechanism to restrain the battery on each side. At the same time, since the helium pipeline is always connected to the battery's filling hole, helium can automatically return to the battery during the flattening and straightening process, realizing the helium return function equivalent to a helium filling pin device, and the maximum amount of helium returned is much greater than that of a helium filling pin device.

[0049] The specific steps of the method for restoring the dented casing of a square battery according to an embodiment of this application are as follows:

[0050] S1. The battery moves along the logistics line to the loading / unloading platform 19 at the bottom of the vacuum chamber. The loading / unloading platform 19 rises into the vacuum chamber 8 and fits snugly against the bottom surface of the vacuum chamber. Both the loading / unloading platform 19 and the loading / unloading openings at the bottom of the vacuum chamber are equipped with rubber sealing rings to ensure a tight fit between the loading / unloading platform 19 and the bottom of the vacuum chamber, preventing gas leakage from the contact area.

[0051] S2. When the loading and unloading platform 19 carrying the battery enters the vacuum chamber, firstly, the two large battery clamping mechanisms apply a pressure of 2000±500N through the cylinder to clamp and fix the battery. Then, the battery side clamping mechanism also applies a restraining force of 2000±500N through the cylinder to clamp and fix the battery. Finally, the battery top pressing mechanism applies a vertical downward restraining force of 2000±500N through the cylinder. At this time, the explosion-proof valve 14 and the sealing ring 11 of the top clamping mechanism form a sealed environment. Since it is basically at the same pressure as the inside of the battery, the vacuuming of the entire sealed cavity will not cause the explosion-proof valve to crack or burst. Thus, the battery is completely clamped and fixed.

[0052] S3. After the battery is clamped, the insertion mechanism 15 is pressed tightly onto the battery's liquid injection hole 12, thus forming a completely sealed space between the outside of the battery and the inside of the vacuum cover 8.

[0053] S4. The insertion mechanism 15 evacuates the battery internally. If the vacuum value is set to -(60-10) kPa, it aims to completely remove any residual gas from the battery to prevent oxygen in the air from participating in the internal reaction. Due to the negative pressure inside the battery and in the insertion pipe, after evacuating the battery internally, the control valve of the helium pipeline in the insertion mechanism 15 opens, allowing helium to automatically flow into the battery.

[0054] S5. Vacuuming is performed on the entire vacuum chamber 8 using a gradient vacuuming method. During vacuuming, the battery is connected to a helium gas pipeline via a pin mechanism 15. The battery is under normal pressure or slightly positive pressure. After vacuuming the vacuum chamber 8, a pressure difference will be formed between the inner and outer surfaces of the battery.

[0055] S6. During the flattening process of the battery surface depression under vacuum, the internal volume of the battery increases, leading to a decrease in internal pressure. Helium gas automatically flows back into the battery from the helium gas pipe connected to the insertion structure 15. The internal pressure of the battery is adjusted to a normal pressure or positive pressure state by controlling the pressure value of the external helium gas circuit. This process is equivalent to the helium return function in the normal insertion process, and the amount of helium returned is greater than the amount of helium gas injected into the battery during the ordinary helium-filling insertion process. By shaping the battery appearance through the pressure difference caused by the vacuum chamber 8, the depression problem can be effectively improved, and the normal helium return function can be achieved.

[0056] S7. After completing the entire vacuuming process to improve the battery's appearance, the insertion mechanism seals the injection hole with glue pins, thus completing the battery's dent improvement and sealing. Then, the battery is unloaded onto the loading and unloading platform and sent to the logistics conveyor line to enter the next process, completing the process.

[0057] The technology in this application embodiment creates a pressure difference between the inside and outside of the battery casing by evacuating the external environment of the battery, thus straightening the dented area on the side / large surface of the battery. At the same time, a gradient vacuuming method is used to reduce the rebound phenomenon that occurs during the straightening process of the metal casing, thereby improving the repair effect of straightening. An all-round clamping fixture is used to restrain and fix the battery to prevent changes in appearance and size. Meanwhile, the increased negative pressure inside the battery after straightening allows helium to flow into the battery automatically, achieving the helium return function equivalent to a helium filling and insertion device.

[0058] Experimental example:

[0059] LP57200218-324Ah square aluminum-shell lithium iron phosphate batteries were selected as the test sample cells. The battery length, width, and height were 200mm, 57mm, and 218mm, respectively. Each group of tests used 8 cells that had undergone secondary electrolyte filling. The improvement effect on the battery surface indentation was evaluated by assessing the side concavity. A total of 6 groups of tests were conducted. The control group (groups 1, 3, and 5) used ordinary helium-filled insertion equipment (denoted as M1), while the experimental group (groups 2, 4, and 6) used the battery indentation repair device of this invention (denoted as M2). Except for the insertion process, the manufacturing processes of the control group and the experimental group were completely consistent.

[0060] The vacuum value of the ordinary helium filling and insertion equipment (M1) is set to -(15-20)Kpa, and the return helium pressure values ​​are set as follows: Group 1: -4Kpa, Group 3: 3Kpa, Group 5: 8Kpa. The purpose is to compare the effects of different return helium pressure values ​​on the battery indentation.

[0061] The battery dent repair device (M2) sets the vacuum inside the battery to -18 kPa, and the internal vacuum of the battery to normal pressure. The clamping mechanism's restraint pressure is adjusted to 2000 N ± 50 N. The vacuum chamber is set to a gradient vacuum. The first vacuum takes 8 seconds, the internal pressure of the vacuum chamber is 25 kPa, and the pressure is held for 9 seconds. The second vacuum takes 12 seconds, the internal pressure of the vacuum chamber is 900 kPa, and the pressure is held for 14 seconds. The third vacuum takes 15 seconds, the internal pressure of the vacuum chamber is 90 kPa, and the pressure is held for 13 seconds.

[0062] Record the average indentation values ​​of the positive and negative electrodes for each group of batteries before, after, and after standing, after capacity testing, after aging, after load adjustment, and after sorting. The table below shows the data recording table, with the indentation data for each process corresponding to the average indentation value of each group of 8 batteries.

[0063] Table 1

[0064]

[0065]

[0066] By comparing the battery indentation repair device (M2) and the ordinary pin insertion device (M1) at helium return pressures of -5-0 kPa, 0-5 kPa, and 5-10 kPa, it can be seen that even if the ordinary pin insertion device fills the battery with helium to a positive pressure, it does not have a significant effect on improving the indentation of the battery after sorting. Moreover, the indentation on the side is basically the same as that under normal helium return to a negative pressure state. This indicates that simply increasing the helium return pressure is not enough to flatten the indentation formed on the battery surface.

[0067] Using the battery dent repair device (M2) in conjunction with gradient vacuuming, the improvement effect on battery side dents is very significant. By creating an ultra-high pressure difference between the inside and outside of the battery, the side / large surface can be completely flattened and straightened. As shown in the table above, the dent of the battery after the pin sealing is completed is no more than 0.03mm, which indicates that the battery surface has been basically flattened and straightened. After the sorting process, the dent of the battery can still be controlled within 0.5mm, and the surface dent repair device has a significant effect on repairing the battery surface dents. The reason why there are still slight dents on the battery side is that after the battery is pin sealed, the internal chemical reaction during the aging and capacity testing stage will continue to reduce the amount of gas, and the electrode assembly will cause slight bulging of the large surface during charging and discharging. The internal space of the battery increases while the volume of gas decreases, thereby generating negative pressure and aggravating the inward dent of the battery side.

[0068] The technology in this application embodiment provides a method for improving the concavity of the battery surface, which restores the concavity to a nearly flat state before sealing. Even if negative pressure is generated during the aging and capacity grading stages after sealing, resulting in side concavity, the degree of concavity is significantly reduced. Compared with batteries using ordinary plugging equipment, the concavity of the positive and negative electrodes after sorting is reduced by about 60% ((M1-M2) / M1), which significantly improves the side concavity of the finished battery.

[0069] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention.

[0070] Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of the equivalents of the claims be included within the invention.

[0071] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A device for restoring a dented square battery casing, characterized in that, The device includes a vacuum hood with a bottom opening, and a battery large-face pressing mechanism, a battery side pressing mechanism, a battery top pressing mechanism, and a pin insertion mechanism arranged within the vacuum hood. The top pressing plate of the battery top pressing mechanism has a sealing ring for sealing the explosion-proof valve on the battery cover and a reserved opening corresponding to the battery top injection hole and terminal post. The battery large-face pressing mechanism and the battery side pressing mechanism each include a pair of large-face pressing plates and a pair of side pressing plates, which press the two large faces and two sides of the battery respectively. The large-face pressing plates and the side pressing plates have through holes. The pin insertion mechanism is used to move downward after the top pressing plate presses against the battery cover and insert its pin tube into the injection hole, which fits tightly with the inner wall of the injection hole, thereby evacuating the battery and then injecting protective gas.

2. The device for restoring a dented square battery casing according to claim 1, characterized in that, The bottom of the vacuum hood is provided with a loading and unloading platform. When the loading and unloading platform is raised, it seals with the loading and unloading opening at the bottom of the vacuum hood.

3. The device for restoring a dented square battery casing according to claim 1, characterized in that, The vacuum hood has an air pipe interface for connecting to a vacuum pump to create negative pressure inside the vacuum hood.

4. The device for restoring a dented square battery casing according to claim 1, characterized in that, The battery surface clamping mechanism, the battery side clamping mechanism, and the battery top clamping mechanism are each driven by a linear drive module, which is connected and fixed to the inner wall of the protective cover via a fixing plate.

5. The device for restoring a dented square battery casing according to claim 1, characterized in that, The insertion mechanism has a pre-reserved air connection port for connecting to an external protective air pipeline.

6. The device for restoring a dented square battery casing according to claim 1, characterized in that, After the top pressure plate, the large surface pressure plate, and the side pressure plates are moved to press against the battery position and connected to each other on the sides, the space formed on the inner surface of the cavity is adapted to the size of the battery to be processed.

7. A method for restoring a dent in the casing of a square battery, characterized in that, The device for restoring the dented square battery casing according to any one of claims 1-6 includes the following steps: The battery to be processed is placed inside the protective cover through the bottom opening of the protective cover at the loading and unloading station, so that the loading and unloading station is sealed to the bottom opening. The battery large surface clamping mechanism, battery side clamping mechanism and battery top clamping mechanism are activated in sequence to clamp the large surface, side and top of the battery in sequence, seal the battery explosion-proof valve and complete the battery restraint. The insertion mechanism is pressed tightly onto the battery filling hole, and the battery is evacuated through the insertion mechanism. After the evacuation operation is completed, protective gas is injected into the battery through the insertion mechanism. The protective gas is kept to flow freely in its channel under external pressure changes, so that the internal gas pressure of the battery is at normal pressure or positive pressure. A gradient vacuum is applied to the inside of the vacuum chamber, and the pressure difference between the inner and outer surfaces of the battery restores the surface depressions of the battery casing to a flat state.

8. The method for restoring a dented square battery casing according to claim 7, characterized in that, After the depression in the battery casing is restored to a flat state, the pinning mechanism seals the injection hole with adhesive pins.

9. The method for restoring a dented square battery casing according to claim 7, characterized in that, The vacuum chamber is subjected to gradient evacuation at least three times, with pressure maintained for a period of time after each evacuation; the vacuum level inside the vacuum chamber gradually increases during the three evacuations.

10. The method for restoring a dent in the casing of a square battery according to claim 9, characterized in that, During the first vacuuming, the internal pressure of the vacuum chamber shall not exceed 30 kPa; during the second vacuuming, the internal pressure of the vacuum chamber shall not exceed 1000 Pa; and during the third vacuuming, the internal pressure of the vacuum chamber shall not exceed 100 Pa.

Images