TWI836589B - Molding method of soft pack battery casing - Google Patents

Abstract

The present invention proposes a molding method for a soft pack battery casing, which includes: adjusting the temperature of the sheet material used to make the casing to a working temperature, using the pressure difference of fluid pressure to apply uniform molding pressure on the sheet material, and a two-stage process. Forming step; wherein the preforming step of the first stage forms the sheet material into a preform with a first depth, and the bottom of the preform forms at least one compensation part; the final forming step of the second stage further forms the preform into The final molded part has a deeper second depth. The method of the present invention can realize the manufacturing of shells with high aspect ratio, promote uniform deformation of sheet materials, and the compensation part can compensate for the angular deformation of the bottom of the final molded part, maintain the thinning rate below 30%, avoid cracking, and improve the product Yield.

Description

Molding method of soft pack battery casing

The present invention relates to the technology of manufacturing the casing of the soft-pack battery during the packaging process of the soft-pack battery, and in particular, a method of forming the casing of the soft-pack battery.

Based on the structure and materials of the packaging casing, lithium-ion batteries can basically be divided into: soft-pack batteries that use aluminum laminated film (ALF) to make the casing, and hard batteries that use metal casings (such as steel shells and aluminum shells). shell battery.

The soft pack battery is also called Pouch Cell, named after the outer covering material (aluminum plastic film) of the battery body, and has the following advantages:

1. High specific energy: Because soft-pack batteries are lighter, their capacity is 10~15% higher than that of steel-shell batteries of the same size, and 5~10% higher than that of aluminum-shell batteries.

2. Good electrochemical performance and long life.

3. Flexible design: can be adjusted/customized according to the internal structure of the product.

30以上容易發生破裂或局部減薄率

30%，進而造成漏液或鼓包的問題。 The first step in the soft pack battery packaging process is to make a casing to accommodate the lithium-ion battery core. Currently, casings made of aluminum-plastic film are generally cold stamped, that is, the aluminum-plastic film is stamped through a fixed-size mold under a certain pressure. Form a box-shaped cavity. The structure of the aluminum-plastic film is a thin multi-layer composite structure (in other words, aluminum Plastic film can be regarded as a multi-layer composite structure of plastic/metal/plastic). After stamping, the film layer is prone to thinning and defects such as pinholes and cracks. It is especially prone to breakage at the corners of the box-shaped cavity. In other words, the current technical difficulties faced by using aluminum-plastic film to make soft-pack battery casings include: 1. The material needs good elongation (to avoid incomplete sealing/cracking); 2. Good molding of complex-shaped casings. The ratio is not high; 3. Depth to thickness ratio

A rate above 30 is prone to rupture or local thinning.

30%, causing leakage or bulging problems.

Please refer to Figure 1 and Figure 2. Currently, aluminum plastic film is used to make soft pack battery casing structures, which generally include two structures: double mold cavity (see Figure 1) and single mold cavity (see Figure 2); the outer shell of the double mold cavity The shell includes an upper shell 60a and a lower shell 60b. The upper shell 60a and the lower shell 60b are welded or bonded together at the connection position 61, using an aluminum-plastic film (with a multi-layer structure of plastic/metal/plastic) or a metal sheet. It is not difficult to form a rectangular double-cavity soft-pack battery casing through room/normal temperature stamping. A larger-depth casing can be easily realized to solve the problem of insufficient stamping depth. However, the double-cavity casing of this kind has Welding is difficult and prone to leakage at the welding location. The single-cavity casing includes a lower casing 62a and a cover 62b. The cover 62b is welded or bonded to the top of the lower casing 62a to seal the battery core in the lower casing 62a. In comparison, the design of a single mold cavity can not only increase the energy density, but also allow the use of materials of different thicknesses, and avoid the difficulty of welding the double mold cavity shell and the resulting liquid leakage problem.

On the other hand, although the existing technology can easily produce a basic square shell 71 (see Figure 3), complex-shaped shells (such as the stepped shell 72 shown in Figure 4) and single-cavity shells have become the future battery design trend because they can increase energy density and product reliability. However, complex-shaped shells will be difficult to deform at the corners due to complex stresses, and are prone to local over-thinning or even cracking. Local thinning during the hot stamping process will be more serious, so the success rate is limited, resulting in poor product yield.

In order to overcome the problems encountered in the shell molding of soft pack batteries, the published Chinese invention patent application publication number CN 109647971 A "A method and device for forming a lithium battery aluminum film shell", proposed a technology of pre-pressing and then performing secondary pressing. In addition, the published Chinese invention patent application publication number CN 107925019 A "Apparatus and method for forming a bag-shaped shell of a secondary battery" proposed a technology of air pressure molding.

It is worth noting that the cold stamping performance of aluminum-plastic film is often evaluated by stamping depth. Stamping depth is a key factor in the development of soft-pack batteries towards large size and large battery capacity. Therefore, how to obtain a shell with a larger stamping depth and avoid excessive thinning and cracking is the focus of research by relevant industry players.

75且局部減薄率

30%之軟包電池的外殼。 The problem to be solved by the present invention is to provide a molding method for the casing of a soft pack battery, which can form a shell with a depth-to-thickness ratio

75 and local thinning rate

30% of the soft pack battery casing.

In order to solve the above problems, an embodiment of the method for molding the casing of a soft-pack battery according to the present invention includes the following steps: a material preparation step, a preforming step, and a final molding step.

The material preparation step includes: preparing a sheet material, a preform mold, and a final mold, wherein opposite sides of the sheet material have a first surface and a second surface respectively, and the preform mold has a preform The final mold cavity has a final mold cavity, wherein the first depth of the pre-form mold cavity is less than the second depth of the final mold cavity.

The sheet material is selected from the group consisting of aluminum plastic film, stainless steel and titanium. The thickness of the sheet material is 0.02mm~0.2mm, and the elongation rate at room temperature is 10%~20%.

The preforming steps include:

Adjust the temperature of the sheet material to a working temperature and place the sheet material in a preforming mold, wherein the working temperature is between room temperature and the metal recrystallization temperature of the sheet material or the glass transition temperature of the plastic material;

A first fluid pressure is generated on the first surface of the sheet material, and a second fluid pressure is generated on the second surface. There is a first pressure difference between the first fluid pressure and the second fluid pressure, and the first pressure difference is used to urge the sheet. The material is deformed from the first surface to the second surface until the second surface touches the preform mold cavity to form a preform having a first cavity, wherein at least one compensation portion is formed at the bottom of the preform.

The final molding steps include:

Maintain the temperature of the preform at the described operating temperature, and configure the preform in the final mold;

A third fluid pressure is generated on the first surface, and a fourth fluid pressure is generated on the second surface. There is a second pressure difference between the third fluid pressure and the fourth fluid pressure, and the second pressure difference is used to promote the preform from The first surface deforms in the direction of the second surface until the second surface touches the final mold cavity to form a final molded part having a second cavity. The shape of the second cavity matches the shape of the battery core and is used to accommodate the battery. core; and

The final molded part is removed from the final molding mold and naturally cooled to room temperature.

The method for forming the outer shell of the soft pack battery of the present invention comprises: combining a pre-forming mold and a final forming mold into a continuous mold, and continuously forming the pre-formed part and the final formed part by a continuous molding process.

The preforming step includes: heating the sheet material to the working temperature.

The molding method of the casing of the soft pack battery of the present invention includes: providing a heatable preform mold and a heatable final mold, and using the heatable preform mold and the heatable final mold to heat the sheet material to the stated operating temperature.

The molding method of the casing of the soft pack battery of the present invention includes: forming a convex portion on the inner bottom surface of the preform mold cavity, and forming the convex-shaped compensation portion at the bottom of the preform through the convex portion.

The fluid pressure mentioned comes from air pressure or hydraulic pressure.

The preforming step includes: forming an inclined side wall on the preform.

The method for forming the outer shell of the soft pack battery of the present invention includes: dynamically adjusting the first pressure difference and/or the second pressure difference.

The method for forming the casing of the soft pack battery of the present invention includes: increasing the pressure differences as time goes by.

The molding method of the casing of the soft pack battery of the present invention includes: reducing the pressure differences as time goes by.

The method for forming the outer shell of the soft pack battery of the present invention comprises: forming a diamond-like coating on the inner wall surface of the pre-forming cavity and the final forming cavity.

75且局部減薄率

30%之軟包電池的外殼；本發明採用留料設計的預成型步驟，在預成型件的底部形成至少一個補償部，用於補償該最終成型件的底部的角位的形變，將減薄率維持在30%以下，能夠避免軟包電池的外殼過度減薄或局部減薄，以及破裂的問題發生，提高良率。 The advantages and effects of the method for forming the shell of the soft pack battery of the present invention are that the shell of the soft pack battery can be reliably manufactured and a thickness ratio of

75 and local thinning rate

The present invention adopts a pre-forming step with a material retention design to form at least one compensation portion at the bottom of the pre-formed part to compensate for the deformation of the corner of the bottom of the final molded part, and maintains the thinning rate below 30%, which can avoid excessive thinning or local thinning of the shell of the soft-pack battery, as well as cracking problems, thereby improving the yield.

【Learning Technology】

60a: Upper shell

60b: Lower shell

61:Connection position

62a: Lower shell

62b:Block

71: Square shell

72: Ladder type shell

【The present invention】

C1: Pre-molding cavity (see Figure 5)

C2: Final mold cavity (see Figure 6)

D1: First Depth

D2: Second depth

10: Preform mold

10a: Upper mold

10b: Lower mold

11: First channel

12: Second channel

13:Protruding part

20:Final mold

20a: Upper mold

20b: Lower mold

21:Third channel

22:The fourth channel

30: Thin sheet material

31: First surface

32: Second surface

40: Preforms

41:First cavity

42:Compensation Department

43: Leaning sidewalls

50:Final molded parts

51: Second cavity

Figure 1 shows the cross-sectional structure of the outer shell of a known soft pack battery using a double-mold cavity structure.

Figure 2 shows the cross-sectional structure of the outer shell of a known soft pack battery using a single cavity structure.

Figure 3 shows a schematic diagram of the structure of a square outer shell of a known soft pack battery.

Figure 4 shows a schematic diagram of the structure of a soft pack battery with a complex outer shell.

Figure 5 shows a cross-sectional structural diagram of a preforming mold for implementing the forming method of the present invention.

Figure 6 is a cross-sectional structural view of a final mold for implementing the molding method of the present invention.

Figures 7-1 to 7-8 are schematic diagrams showing the continuous steps of implementing the molding method of the present invention.

The following is a more detailed description of the specific implementation of the present invention in conjunction with the attached drawings and examples, so that the scheme of the present invention and its advantages in various aspects can be better understood. However, the specific implementation and examples described below are only for the purpose of illustration, not for limiting the present invention.

The preferred implementation of the method for forming the shell of the soft pack battery of the present invention basically includes: a material preparation step S1, a pre-forming step S2, and a final forming step S3. Basically, the method for forming the shell of the soft pack battery of the present invention includes the following features.

(1) The casing of the pouch battery is manufactured in two stages; first, a preform is formed through a preforming step in the first stage, and the preform is formed into a final molded part of the casing through a final forming step in the second stage; wherein The preforming step uses a material retention design to form at least one compensation portion at the bottom of the preform to compensate for the angular deformation and thinning of the bottom of the final formed part, maintaining the thinning rate of the final formed part below 30%. , which can avoid the problem of excessive thinning or even cracking of the final molded part.

(2) Utilize fluid pressure to form the casing of the soft pack battery; the method of the present invention applies different fluid pressures to both sides of the sheet material used to make the casing, and the pressure difference causes The sheet material is gradually and uniformly deformed under uniform stress, and then a preform and a final molded part are respectively formed in the aforementioned two stages, which can avoid cracking and local thinning of the sheet material and improve the yield rate.

(3) The molding method of the outer shell of the soft pack battery of the present invention performs the molding operation of the preform and the final molded part at an appropriate working temperature depending on the thin sheet material used. The working temperature is between room temperature and the metal recrystallization temperature of the thin sheet material (when the thin sheet material is a metal material) or the glass transition temperature of the plastic material (when the thin sheet material is an aluminum plastic film). The area of the preform can be evenly increased to the area of the final molded part. In the final molding step, the thin sheet material directly covers the surface of the final molding cavity, reducing the relative movement between the thin sheet material and the surface of the final molding cavity and reducing the friction force generated, making it less likely to break.

Please refer to Figures 5 and 6, which show the cross-sectional structure diagrams of a preforming mold and a final forming mold for implementing the forming method of the present invention; wherein the material preparation step S1 includes: preparing a thin sheet material 30, a preforming mold 10, and a final forming mold 20; wherein the preforming mold 10 has a preforming cavity C1 (see Figure 5) for forming the thin sheet material 30 into a preformed part 40, and the final forming mold 20 has a final forming cavity C2 (see Figure 6) for further forming the preformed part 40 into a final formed part 50, and the final formed part 50 is a shell for accommodating a battery core, and in principle, the size of the preformed part 40 is smaller than that of the final formed part 50. In a preferred embodiment, the first depth D1 of the preform 40 is less than the second depth D2 of the final molded part 50, preferably, D2=1.01~1.30D1.

75 且局部減薄率

30%之軟包電池的外殼，提高產品良率。 In a preferred embodiment, the original thickness T0 of the sheet material 30 is 0.02mm~0.2mm, and the elongation rate at room temperature is 10%~20%. In a preferred embodiment, the cross-sectional thickness at the thinnest position of the final molded part 50 is T2. The method of the present invention can reliably achieve a high depth-to-thickness ratio (depth-to-thickness ratio: D2/T0) and reduce the thinning rate (thinning rate). (T0-T2)/T0), the depth-to-thickness ratio can be formed

75 and local thinning rate

30% of the soft pack battery casing improves product yield.

The opposite sides of the sheet material 30 have a first surface 31 and a second surface 32 respectively (see Figure 7-1). The forming method of the present invention is not only suitable for forming aluminum-plastic films, but also can be applied to metal sheet materials. In other words, in another preferred embodiment, the sheet material can be metallic stainless steel or titanium.

The preferred implementation method of the preforming step S2 includes:

S2.1 Adjust the temperature of the sheet material 30 to a working temperature, and configure the sheet material 30 in the preform mold 10 (see Figure 7-1 and Figure 7-2), where the working temperature is between room temperature and the metal of the sheet material. Between the recrystallization temperature or the glass transition temperature of the plastic material; the main structure of the aluminum-plastic film has three layers, including nylon (PA), aluminum (AL) and cast polypropylene (CPP) film as protective layers. The glass transition temperature of the plastic material is the glass transition temperature of the protective layer. For example, the glass transition temperature of nylon (also known as Nylon) is 57°C.

S2.2 generates a first fluid pressure on the first surface 31 of the sheet material 30 and a second fluid pressure on the second surface 32. There is a first pressure difference between the first fluid pressure and the second fluid pressure, using The first pressure difference causes the sheet material 30 to deform from the first surface 31 to the second surface 32 (see Figure 7-3) until the second surface 32 touches the preform cavity C1 to form a first cavity 41. Preform 40 (see Figure 7-4), wherein the bottom of the preform 40 forms at least one compensation portion 42. The maximum thinning rate of the preform 40 ((original thickness T0 - thinnest material thickness of the preform)/original thickness) is less than (<) 5%.

Referring to FIG. 5 , a preferred embodiment of the preforming mold 10 includes: an upper mold 10a and a lower mold 10b. The lower mold 10b of the preforming mold 10 has a preforming cavity C1. The upper mold 10a can cover the upper part of the lower mold 10b to press the sheet material 30 between the upper mold 10a and the lower mold 10b (see FIG. 7-2 ). The second surface 32 of the sheet material 30 faces the preforming cavity C1. The upper mold 10a has a first channel 11. The lower mold 10b has a second channel 12 connecting the preforming cavity C1 and the outside. In one embodiment, the lower mold 10b is configured with a plurality of second channels 12. These second channels 12 connect the opening of the preforming cavity C1. The openings are evenly distributed on the inner bottom surface of the preforming cavity C1. The first channel 11 and the second channel 12 are respectively connected to a fluid pressure source through a valve that can be controlled to open or close (such as a pneumatic solenoid valve or a hydraulic solenoid valve) to obtain fluid pressure. The fluid pressure can be pneumatic pressure or hydraulic pressure. The preferred implementation method is to use pneumatic pressure to provide the fluid pressure required by the method of the present invention. The fluid pressure enters the preforming mold 10 through the first channel 11 to generate a first fluid pressure on the first surface 31 of the sheet material 30. The fluid pressure enters the preforming mold 10 through the second channel 12 to generate a second fluid pressure on the second surface 32 of the sheet material 30. There is a first pressure difference between the first fluid pressure and the second fluid pressure.

The present invention adopts the preforming step of leaving material design, and designs a convex portion 13 on the inner bottom surface of the preform cavity C1. The bottom of the preform 40 forms a convex-shaped compensation portion 42 through the convex portion 13 (see figure). 7-4), the function of the compensation part 42 is to reserve more material at the bottom of the preform 40, so that the preform 40 is molded into the final molded part 50 in the final molding step by covering the molding instead of Stretch molding can reduce the impact of friction caused by forward pressure, avoid shell rupture and local thinning, and improve yield. In a preferred embodiment of the method of the present invention, it includes forming an inclined side wall 43 (see Figure 7-4) on the preform 40 to reduce friction.

The final molding step S3 includes: S3.1 maintaining the temperature of the preform 40 at the described operating temperature, and disposing the preform 40 in the final mold 20 (see Figures 7-5 and 7-6); S3.2 generates a third fluid pressure on the first surface 31 and a fourth fluid on the second surface 32 There is a second pressure difference between the third fluid pressure and the fourth fluid pressure, and the second pressure difference is used to promote the deformation of the preform 40 from the first surface 31 to the second surface 32 (see Figure 7-6) , until the second surface 32 touches the final mold cavity C2 to form the final molded part 50 having a second cavity 51 (see Figures 7-7 and 7-8), the shape of the second cavity 51 and the shape of the battery core Matching to accommodate battery cells; and S3.3 Take out the final molded part 50 from the final mold 20 and then naturally cool to room temperature (see Figure 7-8).

In a preferred embodiment of the method of the present invention, the method includes: dynamically adjusting the first pressure difference and/or the second pressure difference, so that uniform molding pressure can be applied to the sheet material 30 . A preferred implementation of dynamic adjustment is to increase the first pressure difference and/or the second pressure difference over time; another preferred implementation of dynamic adjustment is to reduce the first pressure difference and/or the second pressure difference over time. Second pressure difference.

Referring to FIG. 6 , a preferred embodiment of the final molding die 20 includes: an upper mold 20a and a lower mold 20b, wherein the lower mold 20b of the final molding die 20 has a final molding cavity C2, the upper mold 20a can cover the upper part of the lower mold 20b to press the preform 40 between the upper mold 20a and the lower mold 20b, and the second surface 32 faces the final molding cavity C2. The upper mold 20a has a third channel 21, and the lower mold 20b has a fourth channel 22 connecting the final molding cavity C2 and the outside. In one embodiment, the lower mold 20b is configured with a plurality of fourth channels 22, and these fourth channels 2 2 The openings connected to the final molding cavity C2 are evenly distributed on the inner bottom surface of the final molding cavity C2. The third channel 21 and the fourth channel 22 are connected to the fluid pressure source through valves that can be controlled to open or close (such as pneumatic solenoid valves or hydraulic solenoid valves) to obtain fluid pressure. The fluid pressure can be pneumatic pressure or hydraulic pressure. The preferred implementation method is to use pneumatic pressure to provide the fluid pressure required by the method of the present invention. The fluid pressure enters the final molding mold 20 through the third channel 21 to generate a third fluid pressure on the first surface 31, and the fluid pressure enters the final molding mold 20 through the fourth channel 22 to generate a fourth fluid pressure on the second surface 32.

In a preferred embodiment of the method of the present invention, the method includes: forming a Diamond-like Carbon (DLC) coating on the inner side walls of the preformed mold cavity C1 and the final molded cavity C2, for example, on the inner walls of the preformed mold cavity C1 and the final molded cavity C2. The vertical surface of the molding cavity C2 is coated with DLC coating, which can reduce the friction of the sheet material 30 in the preforming mold cavity C1 and the final molding cavity C2 during the molding process.

In a preferred embodiment of the method of the present invention, the method includes: directly heating the sheet material 30 to reach the working temperature. In another embodiment, the method includes: providing a preform mold 10 that can be heated and a final mold 20 that can be heated, and heating the sheet material 30 to the working temperature using the preform mold 10 that can be heated and the final mold 20 that can be heated.

In a preferred embodiment of the method of the present invention, the method includes: juxtaposing the preform mold 10 and the final mold 20 to form a continuous mold, and continuously molding the preform 40 and the final mold 50 in a continuous molding process, which can be more efficient. Continuously formed pouch battery casing.

Although the present invention has been disclosed through the above-mentioned embodiments, they are not intended to limit the present invention. Personnel skilled in the art may make some changes and modifications within the spirit and scope of the present invention. Therefore, the scope of patent protection of the present invention shall be subject to the definition of the claims of this application.

20:Final mold

20a: Upper mold

20b: Lower mold

40: Preform

42:Compensation Department

43: Leaning sidewalls

Claims (11)

A method for forming a shell of a soft pack battery, including the following steps: a material preparation step, including: preparing a sheet material, a preforming mold, and a final forming mold. The sheet material is selected from aluminum plastic film, stainless steel, and titanium. The thickness of the sheet material is 0.02mm~0.2mm, and the normal temperature elongation rate is 10%~20%. The opposite sides of the sheet material have a first surface and a second surface respectively, and the preform mold It includes an upper mold and a lower mold. The lower mold has a preformed mold cavity. The upper mold can cover the top of the lower mold to compress the sheet material between the upper mold and the lower mold. , the inner bottom surface of the preformed mold cavity has a convex portion, the upper mold has a first channel, the lower mold has a plurality of second channels connecting the preformed mold cavity and the outside, and the second channels communicate with the preformed mold cavity. The openings of the mold cavity are evenly distributed on the inner bottom surface of the preform mold cavity. The first channel and the second channel are respectively connected to a fluid pressure source through a valve that can be controlled to open or close to obtain fluid pressure. The final mold cavity is There is a final forming mold cavity, the first depth of the preforming mold cavity is less than the second depth of the final forming mold cavity; a preforming step includes: adjusting the temperature of the sheet material to a working temperature, and adjusting the The sheet material is arranged in the preform mold, the second surface of the sheet material faces the preform mold cavity, and the working temperature is between room temperature and the metal recrystallization temperature of the sheet material or the glass transition temperature of the plastic material; A first fluid pressure is generated on the first surface of the sheet material, and a second fluid pressure is generated on the second surface. The combination of the first fluid pressure and the second fluid pressure There is a first pressure difference, and the first pressure difference is used to promote the sheet material to deform in the direction from the first surface to the second surface until the second surface touches the preformed mold cavity to form a first cavity. A preform, the bottom of the preform forms at least one compensation part; and a final molding step includes: maintaining the temperature of the preform at the working temperature, and arranging the preform at the final molding Mold, the final molding mold includes an upper mold and a lower mold, the lower mold of the final molding mold has a final molding cavity, the upper mold of the final molding mold can cover the lower mold of the final molding mold above, to press the preform between the upper mold of the final forming mold and the lower mold of the final forming mold. The upper mold of the final forming mold has a third channel, and the final forming mold The lower mold has a plurality of fourth channels connecting the final mold cavity and the outside. The openings of the fourth channels connecting the final mold cavity are evenly distributed on the inner bottom surface of the final mold cavity. The third channel and The fourth channels are respectively connected to a fluid pressure source through a valve that can be controlled to open or close to obtain fluid pressure. The second surface faces the final mold cavity; a third fluid pressure is generated on the first surface, and a third fluid pressure is generated on the first surface. The two surfaces generate a fourth fluid pressure, and there is a second pressure difference between the third fluid pressure and the fourth fluid pressure. The second pressure difference is used to urge the preform from the first surface to the second surface. Deform in the direction until the second surface touches the final mold cavity to form a final molded part having a second cavity; The final molded part is taken out from the final mold and allowed to cool to room temperature naturally. The method for forming the outer shell of the soft pack battery as described in claim 1 includes: combining the pre-forming mold and the final forming mold into a continuous mold, and continuously forming the pre-formed part and the final formed part by a continuous molding process. According to the molding method of the shell of the soft-pack battery described in claim 1, the second depth = 1.01~1.30 first depth. As claimed in claim 1, the preforming step includes: heating the sheet material to the working temperature. The method for forming the outer shell of the soft pack battery as described in claim 1 includes: providing the pre-forming mold that can be heated and the final forming mold that can be heated, and heating the sheet material to the working temperature using the pre-forming mold that can be heated and the final forming mold that can be heated. As claimed in claim 1, the fluid pressure comes from pneumatic pressure or hydraulic pressure. As claimed in claim 1, the preforming step includes: forming an inclined side wall on the preform. The method for forming the outer shell of the soft pack battery as described in claim 1 includes: dynamically adjusting the first pressure difference and/or the second pressure difference. The method for forming the outer shell of the soft pack battery as described in claim 9 includes: increasing the pressure difference as time increases. The method for forming the casing of the soft-pack battery as described in claim 9 includes: reducing the pressure difference as time increases. The method for forming the casing of a soft-pack battery according to claim 1 includes: forming a diamond-like coating on the inner side walls of the preformed mold cavity and the final molded cavity.

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