Charging equipment and lithium ion battery processing method adopting same

Abstract

The invention relates to the technical field of lithium ion battery processing, in particular to charging equipment which comprises a plurality of clamp baffles. Baffle structures are arranged at the two ends of the clamp baffle; a battery is arranged between every two adjacent clamp baffles. The battery comprises a tab side thinned surface; the baffle plate structure is propped against the side thinned surface of the tab; a plurality of clamp baffles are arranged on the charging equipment; therefore, the charging equipment can realize simultaneous hot-pressing operation of a plurality of batteries, and the production efficiency is greatly improved; meanwhile, the hot-pressing operation of the battery can be realized by arranging the clamp baffle on the charging equipment, and no more hot-pressing equipment needs to be added before charging, so that the cost of purchasing the hot-pressing equipment is reduced; the baffle structures are arranged at the two ends of the clamp baffle and abut against the thinned face of the tab side of the battery, so that the thinned area of the tab side of the battery and the area with the normal thickness are identical in stress, and shrinkage lines of the PP diaphragm can be effectively eliminated.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion battery processing, and in particular to a charging device and a lithium ion battery processing method using the charging device. Background Art

[0002] Lithium-ion batteries using PP (Polypropylene) diaphragms will experience low capacity and a decrease in electrical performance. The fundamental reason is that the PP diaphragm is stretched in one direction, and internal stress is generated inside the diaphragm that cannot be released. After being soaked in electrolyte, the internal stress is slowly released, and the diaphragm shrinks to produce raised lines, which makes the positive and negative electrodes and the diaphragm fit worse and cannot be in direct contact. The internal resistance at the position where the positive and negative electrodes and the diaphragm are not in contact becomes larger, and the lithium ion transmission becomes worse, resulting in the precipitation of active lithium, which reduces the capacity and electrical performance of the battery. Hot pressing the battery cell after filling and before pre-charging can improve the capacity and electrical performance of the battery to a certain extent, but it cannot completely solve the problem. During the pre-charging process, as the charging progresses, , the electrode begins to rebound and become thicker, the bonding force between the diaphragm and the electrode decreases, and the shrinkage lines of the diaphragm will reappear; the existing method is to roll the battery once before pre-charging to flatten the shrinkage lines of the diaphragm, but the rolling method is not effective. After subsequent charging and discharging, active lithium will still precipitate from the negative electrode of the battery, affecting the capacity and electrical performance of the battery; another method is to hot-press the battery before pre-charging. At this time, an additional hot-pressing equipment is required, which increases the cost, and the hot-pressing equipment is inefficient; the hot-pressing equipment is flat, but the battery has a thinning area of a certain width near the pole ear side, and the force on the thinning area is smaller than that on the large surface area. The pressure cannot eliminate the shrinkage lines of the diaphragm near the pole ear side, affecting the capacity and electrical performance of the battery.

[0003] After searching, the applicant found that the Chinese patent document with application number 201811287195.7 disclosed a lithium battery positive electrode material processing equipment and a processing method thereof on January 22, 2019, comprising four dilution pillars, and a dilution box is installed on the upper end faces of the four dilution pillars. The four dilution pillars provide uniform support for the dilution box, and four waterproof adjustment branches are symmetrically installed around the upper end face of the dilution box. The four waterproof adjustment branches serve to prevent liquid splashing during the dilution process; the waterproof adjustment branch includes an adjustment support plate obliquely welded on the dilution box, and a No. 1 ear seat is installed on the adjustment support plate. A No. 2 hydraulic cylinder is installed between the No. 1 ear seat through a pin shaft, and the top of the No. 2 hydraulic cylinder is installed on the No. 2 ear seat through a pin shaft. The No. 2 ear seat is welded to the waterproof board, and the bottom end of the waterproof board is installed on the upper end of the dilution box through a hinge; this device also cannot solve the above technical problems.

[0004] Therefore, in order to improve or solve at least one of the above problems, it is necessary to provide a charging device that can eliminate the shrinkage lines of the diaphragm on the battery tab side and can perform hot pressing of multiple batteries at the same time. Summary of the Invention

[0005] The object of the present invention is to provide a charging device that can eliminate the shrinkage lines of the diaphragm on the side of the battery tab and can perform hot pressing of multiple batteries at the same time.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a charging device, including multiple clamp baffles; baffle structures are provided at both ends of the clamp baffles; batteries are provided between adjacent clamp baffles; the battery includes a thinned surface on the pole ear side; the baffle structure is tightly abutted against the thinned surface on the pole ear side.

[0007] The baffle structure includes a compressed foam board; the compressed foam board includes an inclined surface; the inclined surface is tightly pressed against the thinned surface on the side of the tab.

[0008] A thermal pad is provided on the side of the clamp baffle close to the battery; the thermal pad is provided between the compressed foam board and the clamp baffle.

[0009] A resistance wire is provided in the fixture baffle; the resistance wire is connected to a power supply; a cooling water pipe is provided on the fixture baffle; a water inlet pipe and a water outlet pipe are respectively provided at the ends of the fixture baffle; the water inlet pipe and the water outlet pipe are both connected to the cooling water pipe.

[0010] The clamp baffle includes a first clamp baffle and a second clamp baffle; multiple second clamp baffles are arranged between adjacent first clamp baffles; a side plate is provided on one side of the first clamp baffle; a cylinder is provided on the side plate, and the cylinder includes a piston rod; the piston rod is connected to the first clamp baffle.

[0011] A lithium ion battery processing method using the charging device comprises the following steps:

[0012] S1: stacking the positive electrode sheet, the negative electrode sheet and the separator of the battery into a core pack, performing the first hot pressing, and aging the battery;

[0013] S2: placing the battery into a charging device for a second hot pressing; and pre-charging the battery;

[0014] S3: placing the battery at rest, placing the battery in the charging device for a third hot pressing, and forming the battery.

[0015] The first hot pressing, the second hot pressing and the third hot pressing all include:

[0016] The temperature of the clamp baffle is raised to 70° C. to 90° C.; the battery is placed between the two clamp baffles; the clamp baffles apply a pressure of 0.076 MPa to 0.13 MPa to the battery and maintain it for 5 min to 10 min.

[0017] Said S1 comprises:

[0018] S11: After the core package is hot-pressed for the first time, the core package is welded, packaged and baked. After the battery is filled with electrolyte, it is aged at high temperature for 48 hours to allow the electrolyte to fully infiltrate the positive electrode sheet and the negative electrode sheet.

[0019] The S2 includes:

[0020] S21: After the second hot pressing of the battery is completed, the water inlet pipe transports cooling water to the cooling water pipe to cool the fixture baffle; when the temperature of the fixture baffle drops to room temperature, the fixture baffle continues to apply a pressure of 0.076Mpa to 0.13Mpa to the battery, and after maintaining it for 5 minutes, the fixture baffle applies a preset pressure to the battery, and the battery is pre-charged.

[0021] The S3 includes:

[0022] S31: After the third hot pressing of the battery is completed, the water inlet pipe transports cooling water to the cooling water pipe to cool the fixture baffle; when the temperature of the fixture baffle drops to room temperature, the fixture baffle continues to apply a pressure of 0.076Mpa to 0.13Mpa to the battery, and after maintaining for 5 minutes, the fixture baffle applies a preset pressure to the battery, and the battery is formed. After formation, the battery is completed through degas, secondary packaging, capacity division, and aging.

[0023] The beneficial effects of the present invention are:

[0024] The charging device of the present invention is provided with a plurality of clamp baffles; the battery is placed on two of the clamp baffles for hot pressing operation; thus, the charging device can realize hot pressing operation of multiple batteries at the same time, greatly improving production efficiency; at the same time, the clamp baffles are provided on the charging device to realize hot pressing operation of the battery, and there is no need to add an additional hot pressing device before charging, thereby reducing the cost of purchasing hot pressing equipment.

[0025] Both ends of the clamp baffle of the present invention are provided with a baffle structure, which is a compressed foam plate. The compressed foam plate is pressed against the thinned surface of the battery's pole ear side, so that the thinned area on the battery's pole ear side is subjected to the same force as the normal thickness area, which can effectively eliminate the shrinkage lines of the PP diaphragm; the charging equipment has the functions of heating and rapid cooling, which meets the rapid cooling and shaping function required by the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings, in which:

[0027] Figure 1 It is a structural schematic diagram of the charging device of the present invention.

[0028] Figure 2 Schematic diagram of the battery installation state of the present invention.

[0029] Figure 3 It is a structural schematic diagram of the clamp baffle of the present invention.

[0030] The marks in the above figure are:

[0031] The following are marked in the figure:

[0032] 1. Fixture baffle, 101. Cooling water pipe, 102. Water inlet pipe, 103. Water outlet pipe,

[0033] 2. Battery,

[0034] 3. Thinning surface of the tab side,

[0035] 4. Thermal pad,

[0036] 5. Compressed foam board, 501, inclined surface,

[0037] 6. First fixture baffle, 601, second fixture baffle, 602, side plate,

[0038] 7. Install the box, 701, and the limit rod. DETAILED DESCRIPTION

[0039] The following is a further detailed description of the specific implementation methods of the present invention through the description of the embodiments with reference to the accompanying drawings, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention and to facilitate their implementation.

[0040] Figure 1-3 The charging device shown includes multiple clamp baffles 1; baffle structures are provided at both ends of the clamp baffles 1; batteries 2 are provided between adjacent clamp baffles 1; the batteries 2 include thinned surfaces 3 on the tab side; and the baffle structures are tightly pressed against the thinned surfaces 3 on the tab side.

[0041] The charging device is provided with multiple clamp baffles 1; the battery 2 is placed on two clamp baffles 1 for hot pressing operation; thus, the charging device can realize hot pressing operation of multiple batteries 2 at the same time, greatly improving production efficiency; at the same time, the clamp baffle 1 is provided on the charging device to realize hot pressing operation of the battery 2, and there is no need to add an additional hot pressing device before charging, which reduces the cost of purchasing hot pressing equipment; both ends of the clamp baffle 1 of the present invention are provided with a baffle structure, and the baffle structure is tightly pressed against the thinned surface 3 on the tab side of the battery 2, so that the thinned area on the tab side of the battery is subjected to the same force as the normal thickness area, which can effectively eliminate the shrinkage lines of the PP diaphragm; the charging device has the functions of heating and rapid cooling, which meets the rapid cooling and shaping function required by the battery 2.

[0042] The baffle structure includes a compressed foam plate 5 ; the compressed foam plate 5 includes an inclined surface 501 ; the inclined surface 501 is pressed tightly against the tab side thinned surface 3 .

[0043] The cross section of the compressed foam plate 5 is triangular; the inclined surface 501 of the compressed foam plate 5 has an inclination angle of 3°-6°, which is used to offset the thickness of the thinned area on the core package tab side, so that the battery 2 is evenly stressed as a whole, and can more effectively eliminate the shrinkage lines produced by the diaphragm on the core package tab side.

[0044] A thermal pad 4 is provided on the side of the clamp baffle 1 close to the battery 2 ; the thermal pad 4 is provided between the compressed foam board 5 and the clamp baffle 1 .

[0045] The thermal pad 4 is a silicone thermal pad; the shell of the clamp baffle 1 is a metal shell, and the thermal pad 4 is in contact with the clamp baffle 1 and the battery 2; when the clamp baffle 1 is electrically heated, the thermal pad 4 transfers the heat of the clamp baffle 1 to the battery 2, thereby achieving good heating of the battery 2.

[0046] A resistance wire is provided in the fixture baffle 1; the resistance wire is connected to a power supply; a cooling water pipe 101 is provided on the fixture baffle 1; an inlet pipe 102 and an outlet pipe 103 are provided at the ends of the fixture baffle 1; the inlet pipe 102 and the outlet pipe 103 are both connected to the cooling water pipe 101.

[0047] The power supply heats the resistance wire, and the resistance wire heats the fixture baffle 1. The shell of the fixture baffle 1 is a metal shell with good thermal conductivity. The resistance wire is installed inside the fixture baffle 1. A cooling water pipe 101 is provided in the fixture baffle 1. The water inlet pipe 102 inputs low-temperature coolant into the cooling water pipe 101. The low-temperature coolant exchanges heat with the fixture baffle 1, thereby rapidly reducing the temperature of the fixture baffle 1. The coolant after heat exchange in the cooling water pipe 101 is discharged from the water outlet pipe 103.

[0048] The clamp baffle 1 includes a first clamp baffle 6 and a second clamp baffle 601; multiple second clamp baffles 601 are arranged between adjacent first clamp baffles 6; a side plate 602 is provided on one side of the first clamp baffle 6; a cylinder is provided on the side plate 602, and the cylinder includes a piston rod; the piston rod is connected to the first clamp baffle 6.

[0049] The charging device includes an installation box 7; the installation box 7 includes side panels 602; limiting rods 701 are provided on the two side panels 602, and through holes are provided at both ends of the clamp baffle 1, and the limiting rods 701 are provided in the through holes, so as to achieve the limitation of the clamp baffle 1; a cylinder is fixedly connected to the side panel 602, and the piston rod of the cylinder is fixedly connected to the first clamp baffle 6; the cylinder controls the piston rod to extend to clamp the first clamp baffle 6 with the battery 2 and the second clamp baffle 601.

[0050] A method for processing lithium-ion batteries using a charging device comprises the following steps:

[0051] S1: stacking the positive electrode sheet, negative electrode sheet and separator of battery 2 into a core pack, performing the first hot pressing, and aging battery 2;

[0052] S2: placing battery 2 in a charging device for a second hot pressing; pre-charging battery 2;

[0053] S3: The battery 2 is allowed to stand still, and the battery 2 is placed in a charging device for a third hot pressing; the battery 2 is formed.

[0054] In S1, the core package is hot pressed once after lamination is completed to prevent displacement of the pole pieces during the transfer process. In S2, battery 2 is hot pressed a second time before pre-charging. In S3, battery 2 is hot pressed a third time before formation. The second and third hot pressing processes can completely eliminate shrinkage marks on the PP diaphragm caused by stress release, thereby improving the capacity and electrical performance of battery 2.

[0055] The first hot pressing, the second hot pressing and the third hot pressing all include:

[0056] Raise the temperature of the clamp baffle 1 to 70°C to 90°C; place the battery 2 between the two clamp baffles 1; apply a pressure of 0.076Mpa to 0.13Mpa to the battery 2 by the clamp baffle 1 and maintain it for 5min to 10min.

[0057] The battery 2 is hot-pressed by the fixture baffle 1 to completely eliminate the shrinkage lines of the PP diaphragm caused by stress release, thereby improving the capacity and electrical performance of the battery 2.

[0058] S1 includes:

[0059] S11: After the first hot pressing of the core package is completed, the core package is welded, packaged and baked. After the battery 2 is filled with electrolyte, it is aged at high temperature for 48 hours to allow the electrolyte to fully penetrate the positive and negative electrodes.

[0060] S2 includes:

[0061] S21: After the second hot pressing of battery 2 is completed, the water inlet pipe 102 transports cooling water to the cooling water pipe 101 to cool the fixture baffle 1; when the temperature of the fixture baffle 1 drops to room temperature, the fixture baffle 1 continues to apply a pressure of 0.076Mpa to 0.13Mpa to the battery 2, and after maintaining it for 5 minutes, the fixture baffle 1 applies a preset pressure to the battery 2, and the battery 2 is pre-charged.

[0062] After the hot pressing step is completed, turn on the cooling circulating water and immediately cool down the fixture baffle 1. After the charging equipment cools to room temperature, continue to maintain this pressure for 5 minutes. This can not only shape the battery 2, but also remove the gas between the electrodes. Loosen the fixture baffle 1. After this step, the hot pressing and shaping of the battery 2 are completed, and then adjust the pressure to the predetermined pressure for pre-charging.

[0063] S3 includes:

[0064] S31: After the third hot pressing of battery 2 is completed, the water inlet pipe 102 transports cooling water to the cooling water pipe 101 to cool the fixture baffle 1; when the temperature of the fixture baffle 1 drops to room temperature, the fixture baffle 1 continues to apply a pressure of 0.076Mpa to 0.13Mpa to battery 2, and after maintaining for 5 minutes, the fixture baffle 1 applies a preset pressure to battery 2, and battery 2 is formed. After formation, the battery 2 is completed through degas (exhaust or degassing process), secondary packaging, capacity division, and aging.

[0065] Since the formation process of battery 2 is also a process of electrode expansion, battery 2 also needs to be hot-pressed before formation to prevent the diaphragm adhesion from decreasing during the period of standing at room temperature after pre-charging is completed. As the electrode expands during the formation process, the diaphragm shrinks, affecting the capacity and electrical performance of battery 2.

[0066] The specific workflow of the present invention is as follows:

[0067] S1: stacking the positive electrode sheet, negative electrode sheet and separator of battery 2 into a core pack, performing the first hot pressing, and aging battery 2;

[0068] S2: placing battery 2 in a charging device for a second hot pressing; pre-charging battery 2;

[0069] S3: The battery 2 is allowed to stand still, and the battery 2 is placed in a charging device for a third hot pressing; the battery 2 is formed.

[0070] The present invention has been described above with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described method. Any non-substantial improvements made using the method concepts and technical solutions of the present invention, or any direct application of the above-described concepts and technical solutions to other situations without modification, fall within the scope of protection of the present invention.

Claims

1. A charging device, characterized in that: It comprises a plurality of clamp baffles (1); baffle structures are provided at both ends of the clamp baffles (1); batteries (2) are provided between adjacent clamp baffles (1); the batteries (2) comprise tab-side thinned surfaces (3); and the baffle structures are tightly abutted against the tab-side thinned surfaces (3).

2. A charging device according to claim 1, characterized in that: The baffle structure comprises a compressed foam plate (5); the compressed foam plate (5) comprises an inclined surface (501); the inclined surface (501) is tightly pressed against the tab side thinned surface (3).

3. A charging device according to claim 2, characterized in that: A heat-conducting pad (4) is provided on the side of the clamp baffle (1) close to the battery (2); the heat-conducting pad (4) is provided between the compressed foam board (5) and the clamp baffle (1).

4. A charging device according to any one of claims 2-3, characterized in that: A resistance wire is provided in the clamp baffle (1); the resistance wire is connected to a power source; a cooling water pipe (101) is provided on the clamp baffle (1); a water inlet pipe (102) and a water outlet pipe (103) are provided at the ends of the clamp baffle (1); the water inlet pipe (102) and the water outlet pipe (103) are both connected to the cooling water pipe (101).

5. A charging device according to claim 4, characterized in that: The clamp baffle (1) comprises a first clamp baffle (6) and a second clamp baffle (601); a plurality of the second clamp baffles (601) are arranged between adjacent first clamp baffles (6); a side plate (602) is provided on one side of the first clamp baffle (6); a cylinder is provided on the side plate (602), and the cylinder comprises a piston rod; the piston rod is connected to the first clamp baffle (6).

6. A method for processing a lithium-ion battery using the charging device according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: stacking the positive electrode sheet, the negative electrode sheet and the separator of the battery (2) into a core pack, performing a first hot pressing, and aging the battery (2); S2: placing the battery (2) in a charging device for a second hot pressing; and pre-charging the battery (2); S3: placing the battery (2) at rest, placing the battery (2) in the charging device for a third hot pressing, and forming the battery (2).

7. The lithium ion battery processing method according to claim 6, characterized in that: The first hot pressing, the second hot pressing and the third hot pressing all include: The temperature of the clamp baffle (1) is raised to 70°C to 90°C; the battery (2) is placed between the two clamp baffles (1); the clamp baffles (1) apply a pressure of 0.076Mpa to 0.13Mpa to the battery (2) and maintain the pressure for 5 minutes to 10 minutes.

8. The lithium ion battery processing method according to claim 7, characterized in that: Said S1 comprises: S11: After the core package is hot-pressed for the first time, the core package is welded, packaged and baked. After the battery (2) is filled with electrolyte, it is aged at high temperature for 48 hours to allow the electrolyte to fully penetrate the positive electrode sheet and the negative electrode sheet.

9. The lithium ion battery processing method according to claim 8, characterized in that: The S2 includes: S21: After the second hot pressing of the battery (2) is completed, the water inlet pipe (102) delivers cooling water to the cooling water pipe (101) to cool the clamp baffle (1); when the temperature of the clamp baffle (1) drops to room temperature, the clamp baffle (1) continues to apply a pressure of 0.076Mpa to 0.13Mpa to the battery (2), and after maintaining it for 5 minutes, the clamp baffle (1) applies a preset pressure to the battery (2), and the battery (2) is pre-charged.

10. The lithium ion battery processing method according to claim 9, characterized in that: The S3 includes: S31: After the third hot pressing of the battery (2) is completed, the water inlet pipe (102) transports cooling water to the cooling water pipe (101) to cool the fixture baffle (1); when the temperature of the fixture baffle (1) drops to room temperature, the fixture baffle (1) continues to apply a pressure of 0.076Mpa to 0.13Mpa to the battery (2), and after maintaining for 5 minutes, the fixture baffle (1) applies a preset pressure to the battery (2), and the battery (2) is formed. After formation, the battery (2) is completed through degassing, secondary packaging, capacity division, and aging.

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