A baking jig and a baking method for cylindrical batteries

Abstract

This invention discloses a baking fixture for cylindrical batteries, characterized by comprising a heating plate assembly and a thermally conductive sleeve assembly. The sleeve assembly is vertically disposed on the heating plate assembly, and its bottom is thermally conductively fitted to the heating plate assembly. The sleeve assembly includes a sleeve for placing the cylindrical battery to be baked and a heat-conducting block located at the bottom of the sleeve. The upper surface of the heat-conducting block has the same shape as the bottom surface of the cylindrical battery to be baked, so that the bottom surface of the cylindrical battery placed in the sleeve is in contact with the upper surface of the heat-conducting block. This invention has advantages such as reasonable structural design, increased contact area, improved heat conduction efficiency, and improved uniform heating of the battery cell.

Description

Technical Field

[0001] This invention relates to the field of cylindrical battery manufacturing technology, and in particular to a baking fixture and baking method for cylindrical batteries. Background Technology

[0002] Baking plays a crucial role in battery cell manufacturing, as the water content after baking directly affects electrical performance. The baking process is located after mid-stage assembly and before electrolyte injection and sealing. The electrolyte has extremely high requirements for water content, generally controlled below 150 ppm. Moisture content significantly impacts battery capacity, initial efficiency, cycle performance, internal resistance, and thickness. Currently, there are two main baking methods: hot air circulation heating and contact baking. Hot air circulation heating is gradually being phased out due to its poor temperature uniformity, long baking time, and high energy consumption. Contact baking, on the other hand, involves the heating plate directly contacting the battery, resulting in better temperature uniformity and a shorter baking cycle.

[0003] Contact baking mainly consists of baking clamps and a sealed oven body. The baking clamps are equipped with batteries and have an automatic heating function, while the sealed oven body provides a vacuum environment. However, current baking clamps still have the following drawbacks:

[0004] The heating plate has a planar structure, which limits the contact area when baking batteries with non-planar bottoms, thus reducing heat transfer efficiency.

[0005] The heating method is only heat conduction heating from the bottom heating plate, resulting in slow temperature rise and uneven heating of the battery cell. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is: how to provide a baking fixture machine and baking method with a reasonable structural design that can increase the contact area, improve the heat conduction efficiency, and improve the heating uniformity of the battery cell.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A baking fixture for cylindrical batteries is characterized in that it includes a heating plate assembly and a heat-conducting sleeve assembly, wherein the sleeve assembly is vertically disposed on the heating plate assembly and its bottom is thermally conductively attached to the heating plate assembly; the sleeve assembly includes a sleeve for placing the cylindrical battery to be baked and a heat-conducting block located at the bottom of the sleeve, wherein the upper surface of the heat-conducting block is consistent with the bottom surface of the cylindrical battery to be baked, so that the bottom surface of the cylindrical battery placed in the sleeve is attached to the upper surface of the heat-conducting block.

[0009] In the above structure, because the sleeve assembly is thermally conductive and is thermally bonded to the heating plate assembly, both the sleeve and the heat-conducting block can heat up. The upper surface of the heat-conducting block can adhere to the bottom of the cylindrical battery, thereby increasing the contact area between the cylindrical battery and the heating element, improving heat conduction efficiency, and enabling better heating. Furthermore, the sleeve provides positioning for the cylindrical battery, and it itself heats up under the heating of the heating plate assembly, generating thermal radiation on the outside of the cylindrical battery, resulting in a more uniform temperature transition between the upper, middle, and lower layers of the cell.

[0010] Furthermore, the height of the sleeve is consistent with the height of the cylindrical battery to be baked.

[0011] This ensures that the entire cylindrical battery is within the thermal radiation range of the sleeve.

[0012] Furthermore, the heat-conducting block is detachably disposed within the sleeve.

[0013] In this way, cylindrical batteries with different bottom shapes can be adapted by replacing the heat-conducting block.

[0014] Furthermore, the outer diameter of the heat-conducting block is consistent with the inner diameter of the sleeve, and they are coaxially fitted inside the sleeve. The bottom surface of the heat-conducting block is a heat-conducting plane.

[0015] In this way, by using the outer diameter of the heat-conducting block to match the sleeve, gravity can be used to ensure that the heat-conducting block is reliably fitted at the bottom of the sleeve, without the need for additional fixing, which facilitates the assembly and replacement of the heat-conducting block.

[0016] Furthermore, the inner diameter of the sleeve matches the diameter of the cylindrical battery to be baked, so that there is a gap between the cylindrical battery placed inside the sleeve and the sleeve.

[0017] In this way, on the one hand, the cylindrical battery as a whole is within the heat radiation range formed by the sleeve and the heat-conducting block, and has good heating conditions. On the other hand, setting a gap between it and the sleeve is conducive to the escape of moisture from the gap, thus improving the drying efficiency.

[0018] Furthermore, the sleeve has a through-hole, which is located at the lower end of the sleeve.

[0019] In this way, the circulating airflow can be used in conjunction with the baking process, allowing the moisture in the battery cells to escape more easily and improving baking efficiency.

[0020] As an optimization, the outer circumference of the sleeve has a coaxially arranged annular groove located at the lower end of the sleeve; the heating plate assembly has parallel spaced limiting strips, the distance between two adjacent limiting strips matching the outer diameter of the sleeve; both sides of the limiting strips have protruding ridges extending outward along the width direction, the thickness of the protruding ridges being less than the width of the annular groove, and the distance between the protruding ridges and the heating plate assembly being consistent with the distance between the annular groove and the bottom surface of the sleeve; the sleeve is movably engaged with the protruding ridges of the two limiting strips through the annular groove.

[0021] Furthermore, the heating plate assembly has guide strips on both sides, and the two ends of the limiting strip are slidably connected to the guide strips. A locking mechanism is also provided between the limiting strip and the guide strip.

[0022] Furthermore, the bottom of the guide strip has a U-shaped groove that runs through the length direction and is slidably fitted with a slider. The upper surface of the guide strip has a strip-shaped hole that runs through the length direction. The slider has a threaded hole that is directly opposite the strip-shaped hole. Both ends of the limiting strip have bolt holes that run through the strip and are connected to the threaded hole of the slider by bolts that pass through the bolt holes and the strip-shaped hole.

[0023] A method for baking a cylindrical battery, characterized in that the baking fixture described above is first obtained, the cylindrical battery to be baked is placed in a sleeve, and a vacuum baking method is adopted to draw the cavity to negative pressure and heat it to a set temperature for heat preservation baking.

[0024] In summary, the present invention has the advantages of reasonable structural design, which can increase the contact area, improve heat conduction efficiency, and improve the uniformity of cell heating. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of Example 1.

[0026] Figure 2 This is an exploded view of the sleeve assembly in Example 1.

[0027] Figure 3 This is a schematic diagram of the structure of Example 2.

[0028] Figure 4 This is a schematic diagram of the sleeve structure in Example 2. Implementation

[0029] The present invention will be further described in detail below with reference to the embodiments. Example 1:

[0030] like Figure 1 and Figure 2As shown, a baking fixture for a cylindrical battery includes a heating plate assembly 1 and a heat-conducting sleeve assembly 2. The sleeve assembly 2 is vertically disposed on the heating plate assembly 1, and its bottom is thermally conductively attached to the heating plate assembly 1. The sleeve assembly 2 includes a sleeve 21 for placing the cylindrical battery to be baked and a heat-conducting block 22 located at the bottom of the sleeve 21. The upper surface of the heat-conducting block 22 has the same shape as the bottom surface of the cylindrical battery to be baked, so that the bottom surface of the cylindrical battery placed in the sleeve 21 is attached to the upper surface of the heat-conducting block 22.

[0031] In this embodiment, the height of the sleeve 21 is the same as the height of the cylindrical battery to be baked. The heat-conducting block 22 is detachably disposed inside the sleeve 21. The outer diameter of the heat-conducting block 22 is the same as the inner diameter of the sleeve 21 and coaxially fitted inside the sleeve 21. The bottom surface of the heat-conducting block 22 is a heat-conducting plane. Figure 2 As shown.

[0032] For cylindrical batteries with different bottom shapes, the heat-conducting block can be replaced to match the ground surface of the cylindrical battery. During baking, the cylindrical battery is placed inside the sleeve, and the heat from the heating plate assembly is transferred to the heat-conducting block and the sleeve. The heat-conducting block directly heats the bottom surface of the cylindrical battery, while the sleeve provides circumferential heat radiation heating to the cylindrical battery, making the cell heat more evenly heated and greatly improving the baking effect of the cylindrical battery.

[0033] In this embodiment, to further improve the effect of moisture evaporation (escape), the inner diameter of the sleeve 21 matches the diameter of the cylindrical battery to be baked, creating a gap between the cylindrical battery placed inside the sleeve 21 and the sleeve 21. During the baking and dehydration process, in addition to increasing the temperature, it is also necessary to consider the moisture escape channel. The moisture escape channel is directly related to the area; the outer surface of the cylindrical battery has the largest area, providing a more favorable moisture escape channel. Setting a gap between the cylindrical battery and the sleeve ensures that the cylindrical battery has sufficient temperature within a reasonable heat radiation range, and also ensures a moisture escape channel, allowing heated water vapor to quickly escape from the battery cell. Compared to a method of tightly fitting the outer surface of the cylindrical battery, setting a gap allows for higher baking efficiency.

[0034] In addition, in this embodiment, to facilitate the circulating airflow, a ventilation hole 23 is provided through the sleeve 21, located at the lower end of the sleeve 21. This allows for faster airflow between the cylindrical battery and the sleeve, carrying away any escaped moisture and enabling it to continue escaping from the battery cell more effectively.

[0035] Using the baking fixture of this embodiment, during baking, the cylindrical battery to be baked is first placed inside the sleeve, with the bottom of the cylindrical battery in contact with the upper surface of the heat-conducting block. The baking process adopts a vacuum baking method, where the cavity is evacuated to negative pressure, then heated to the set temperature for heat preservation baking. Moisture inside the electrode diffuses to the surface of the object through pressure or concentration difference. Water molecules gain sufficient kinetic energy on the surface and escape into the low-pressure environment of the vacuum chamber after overcoming intermolecular forces. During battery baking, the bottom heating plate and the sleeve provide a heat source, and combined with the vacuum environment circulating airflow (large cavity) and the ventilation holes at the bottom of the fixture, the moisture escapes more quickly. Example 2:

[0036] The main difference between this embodiment and Embodiment 1 is that, Figure 3 and Figure 4 As shown, the sleeve 21 has a coaxially arranged annular groove 24 on its outer circular surface, and the annular groove 24 is located at the lower end of the sleeve 21; the heating plate assembly 1 has parallel spaced limiting strips 3, and the distance between two adjacent limiting strips 3 matches the outer diameter of the sleeve 21; the limiting strips 3 have protruding ridges extending outward along the width direction on both sides, the thickness of the protruding ridges is less than the width of the annular groove 24, and the distance between the protruding ridges and the heating plate assembly 1 is the same as the distance between the annular groove 24 and the bottom surface of the sleeve 21; the sleeve 21 is movably engaged with the protruding ridges of the two limiting strips 3 through the annular groove 24.

[0037] Since cylindrical batteries of different sizes require sleeves 21 of different diameters, the heating plate assembly 1 has guide strips 4 on both sides to accommodate the fixing of different sleeves 21. The two ends of the limiting strips 3 are slidably connected to the guide strips 4, and a locking mechanism is also provided between the limiting strips 3 and the guide strips 4. In this way, the distance between two adjacent limiting strips 3 can be adjusted by the guide strips 4 to meet the fixing requirements of sleeves 21 with different outer diameters.

[0038] In this embodiment, the bottom of the guide bar 4 has a U-shaped groove that runs through the length direction and is slidably fitted with a slider. The upper surface of the guide bar 4 has a strip-shaped hole that runs through the length direction. The slider has a threaded hole that is directly opposite to the strip-shaped hole. The two ends of the limiting bar 3 have bolt holes that run through the bar and are connected to the threaded hole of the slider by bolts that pass through the bolt holes and the strip-shaped hole.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A baking jig for a cylindrical battery, characterized by comprising: The device includes a heating plate assembly (1) and a heat-conducting sleeve assembly (2). The sleeve assembly (2) is vertically disposed on the heating plate assembly (1) and its bottom is thermally conductively attached to the heating plate assembly (1). The sleeve assembly (2) includes a sleeve (21) for placing a cylindrical battery to be baked and a heat-conducting block (22) located at the bottom of the sleeve (21). The upper surface of the heat-conducting block (22) is consistent with the bottom surface of the cylindrical battery to be baked, so that the bottom surface of the cylindrical battery placed in the sleeve (21) is attached to the upper surface of the heat-conducting block (22). The heat-conducting block (22) is detachably disposed inside the sleeve (21); the outer diameter of the heat-conducting block (22) is consistent with the inner diameter of the sleeve (21) and is coaxially fitted inside the sleeve (21); the bottom surface of the heat-conducting block (22) is a heat-conducting plane. The inner diameter of the sleeve (21) matches the diameter of the cylindrical battery to be baked, so that there is a gap between the cylindrical battery placed in the sleeve (21) and the sleeve (21); the sleeve (21) has a through-hole (23), which is located at the lower end of the sleeve (21). The sleeve (21) has a coaxially arranged annular groove (24) on its outer circular surface, and the annular groove (24) is located at the lower end of the sleeve (21); the heating plate assembly (1) has parallel spaced limiting strips (3), and the distance between two adjacent limiting strips (3) matches the outer diameter of the sleeve (21); the limiting strips (3) have protruding ridges extending outward along the width direction on both sides, the thickness of the protruding ridges is less than the width of the annular groove (24), and the distance between the protruding ridges and the heating plate assembly (1) is consistent with the distance between the annular groove (24) and the bottom surface of the sleeve (21); the sleeve (21) is movably engaged with the protruding ridges of the two limiting strips (3) through the annular groove (24).

2. The baking fixture for cylindrical batteries as described in claim 1, characterized in that, The height of the sleeve (21) is the same as the height of the cylindrical battery to be baked.

3. The baking fixture for cylindrical batteries as described in claim 1, characterized in that, The heating plate assembly (1) has guide strips (4) on both sides, and the two ends of the limiting strip (3) are slidably connected to the guide strips (4). The limiting strip (3) and the guide strip (4) also have a locking mechanism.

4. The baking fixture for cylindrical batteries as described in claim 3, characterized in that, The bottom of the guide bar (4) has a U-shaped groove that runs through the length direction and is slidably fitted with a slider. The upper surface of the guide bar (4) has a strip-shaped hole that runs through the length direction. The slider has a threaded hole that is directly opposite to the strip-shaped hole. The two ends of the limiting bar (3) have bolt holes that run through the bar and are connected to the threaded hole of the slider by bolts that pass through the bolt holes and the strip-shaped hole.

5. A method for baking a cylindrical battery, characterized in that, First, obtain the baking fixture as described in any one of claims 1 to 4. Place the cylindrical battery to be baked inside the sleeve and use a vacuum baking method to draw the cavity to negative pressure and heat it to the set temperature for heat preservation baking.

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