A CPP film, an aluminum-plastic film and a soft package lithium battery for packaging the soft package lithium battery

Abstract

This invention belongs to the field of soft-pack lithium battery manufacturing technology, and relates to a CPP film, an aluminum-plastic film, and a soft-pack lithium battery for packaging. The CPP film includes heat-sealing layers on both sides, a composite layer, a support layer containing a polyolefin elastomer adjacent to the inner side of the heat-sealing layer, and a homopolymer polypropylene barrier layer without a polyolefin elastomer adjacent to the support layer and the composite layer. The CPP film provided by this invention, through optimization and improvement of its structure and raw material composition, improves the elastic modulus, barrier properties, and friction coefficient stability of the CPP film. This results in aluminum-plastic films produced using this CPP film exhibiting excellent electrolyte resistance, deep-drawing performance, and anti-curling properties, leading to high-quality soft-pack lithium batteries.

Description

Technical Field

[0001] This invention belongs to the field of soft-pack lithium battery manufacturing technology, and relates to a CPP film, an aluminum-plastic film, and a soft-pack lithium battery for packaging soft-pack lithium batteries. Background Technology

[0002] Due to their advantages such as high safety, high energy density, and flexible shape, soft-pack lithium batteries are widely used in electric vehicles, consumer electronics, and other fields, and are gradually replacing hard-pack batteries.

[0003] The packaging material for soft-pack lithium batteries, also known as aluminum-plastic film, typically consists of a three-layer structure: an outer nylon layer, a middle aluminum foil layer, and an inner CPP film layer. Each layer is bonded together with an adhesive. The inner CPP film is the most critical material affecting the lithium battery packaging effect. The primary function of the CPP film is sealing. Because it comes into direct contact with the electrolyte, in addition to good heat-sealing performance, it also needs good electrolyte resistance and barrier properties to prevent electrolyte penetration and corrosion of the aluminum foil layer, which could lead to battery leakage, short circuits, and other safety issues. Furthermore, when using CPP film to encapsulate lithium batteries, a stamping process is required. To improve stamping resistance, the CPP film also needs good resilience and surface smoothness. The smoothness primarily allows for relative sliding between the aluminum-plastic film and the metal mold during stamping, compensating for the stamping depth and preventing excessive local stretching of the aluminum-plastic film that could cause breakage.

[0004] Currently, CPP films used in soft-pack lithium batteries are typically manufactured using a three-layer co-extrusion casting process. A typical structure is ABA or ABC, with three functional layers: a composite layer, a core layer, and a heat-sealing layer. The heat-sealing layer is mainly made of blends of various materials such as random copolymers of polypropylene, block copolymers of polypropylene, and metallocene polyethylene, along with polyolefin elastomers, achieving good heat-sealing strength over a wide temperature range. Additionally, erucamide-based slip agents and silica anti-sticking agents are added to give the CPP film good surface slip properties. The core layer is usually made of blends of block copolymers of polypropylene, random polypropylene, homopolymers of polypropylene, polyolefin elastomers, and a certain proportion of erucamide-based slip agents, providing barrier properties, toughness, and a certain degree of stiffness. Erucamide-based slip agents are also added to the core layer as an additional supplement to the heat-sealing layer's slip agent. When the heat-sealing layer's slip agent is lost due to environmental temperature and processing, the core layer's slip agent migrates to the heat-sealing layer, maintaining the CPP film's long-lasting slip properties. The composite layer is usually made by blending block copolymer polypropylene, random polypropylene, maleic anhydride-modified polypropylene, etc., with the addition of a certain amount of polyolefin elastomer to improve the deep drawing performance. It also needs to undergo corona treatment during the film-making process to increase the surface wetting tension and polarity, which is conducive to the adhesion of adhesives and improves the composite strength of CPP film layer and aluminum foil layer.

[0005] CN115782337A discloses a CPP film for use in lithium battery encapsulation aluminum-plastic film. The core layer is located between the composite layer and the heat-sealing layer. The core layer comprises 45-65% random copolymer polypropylene with a melting point above 140°C, 10-30% polyolefin elastomer, 15%-30% block or homopolymer with a melting point above 150°C, and 5-10% gel-like block copolymer. This CPP film not only meets the requirement of non-adhesive curing under conventional conditions for aluminum-plastic film, but also, depending on the product effect, the curing temperature can reach 50-70°C, significantly shortening the plasticizing time, improving the curing effect, and increasing production efficiency.

[0006] The above-mentioned three-layer CPP membrane generally suffers from the following problems in practical applications:

[0007] 1. While the addition of polyolefin elastomers to each layer increases the toughness of the CPP film and improves its deep-drawing performance, it alters the crystal structure of polypropylene during extrusion molding, reducing the barrier properties and overall elastic modulus of the CPP film. This allows electrolyte to easily penetrate the aluminum foil layer, leading to battery leakage and open circuits after corrosion, posing a significant threat to the lifespan and safety of pouch lithium batteries. Furthermore, the reduced overall elastic modulus can cause the aluminum-plastic film to curl towards the nylon layer during subsequent stamping, adversely affecting the processing efficiency of pouch lithium batteries. Using the conventional method of increasing the CPP film thickness and decreasing the nylon layer thickness to achieve elastic modulus balance would increase production costs, and the reduced nylon layer is at risk of breakage.

[0008] 2. Erucamide-type migratory slip agents are added to the core layer to supplement the slip performance of the heat-sealing layer. However, their migration direction is unstable. During the composite processing and storage of aluminum-plastic film, the slip agent may migrate to the composite layer side, causing the friction coefficient of the heat-sealing layer of CPP film to fail to maintain a low level. Moreover, excessive slip agent precipitation in the composite layer reduces the surface tension of CPP, which may affect the composite strength of CPP film layer and aluminum foil layer. Summary of the Invention

[0009] The first objective of this invention is to provide a CPP film for packaging soft-pack lithium batteries, overcoming the aforementioned defects of existing CPP films in the prior art.

[0010] The present invention adopts the following technical solution:

[0011] A CPP film for packaging soft-pack lithium batteries includes a heat-sealing layer as two sides, a composite layer, a support layer containing a polyolefin elastomer adjacent to the inner side of the heat-sealing layer, and a homopolymer polypropylene barrier layer without a polyolefin elastomer adjacent to the support layer and the composite layer.

[0012] In the above scheme, the heat-sealing layer mainly serves a sealing function and directly contacts the stamping die during stamping; the support layer provides the necessary mechanical strength for the CPP film; the homopolymer polypropylene barrier layer helps prevent electrolyte penetration, control the stability of the friction coefficient, and improve the elastic modulus of the CPP film; the composite layer is used to bond and laminate with the aluminum foil layer when forming the aluminum-plastic film.

[0013] In existing technologies, CPP films typically have a three-layer structure. To improve heat-sealing and deep-drawing performance, a significant amount of polyolefin elastomer is often added to lower the initial sealing temperature and enhance toughness. However, polyolefin elastomers suffer from low density and poor dispersion. Furthermore, the applicant has discovered that the addition of polyolefin elastomers disrupts the crystal structure of polypropylene, reducing the barrier properties and overall elastic modulus of the CPP film. This allows electrolyte to easily penetrate the aluminum foil layer, causing leakage and corrosion of the aluminum foil. During subsequent aluminum-plastic film stamping, this leads to the aluminum-plastic film curling towards the nylon layer, negatively impacting the processing efficiency of soft-pack lithium batteries. Therefore, this invention improves the structure and composition of the CPP film by dividing the core layer into two layers: a support layer containing polyolefin elastomer to ensure better toughness and improve deep-drawing performance, preventing the aluminum-plastic film from cracking or whitening during stamping. The other layer is a homopolymer polypropylene barrier layer that does not contain polyolefin elastomers, which improves the barrier performance and can effectively avoid the problems of electrolyte penetration and reduction of elastic modulus caused by the addition of polyolefin elastomers.

[0014] The main raw material of the homopolymer polypropylene barrier layer is homopolymer polypropylene. Homopolymer polypropylene has regular and orderly molecular chains, high crystallinity, and good barrier performance. It can make up for the electrolyte penetration defects caused by the destruction of the crystal structure of polypropylene after the addition of polyolefin elastomers to other layers.

[0015] The homopolymer polypropylene barrier layer of this invention contains homopolymer polypropylene but does not contain polyolefin elastomers, increasing the elastic modulus by 50% compared to conventional polypropylene layers, thus preventing curling of the CPP film after it is made into an aluminum-plastic film. Experimental measurements show that the elastic modulus of a 25μm thick nylon film is 1500MPa-2000MPa, the elastic modulus of a polypropylene film is typically 500-1000MPa, while the elastic modulus of the homopolymer polypropylene film can reach over 1500MPa.

[0016] In this design, the support layer and the homopolymer polypropylene barrier layer each provide different functions for the CPP membrane, and neither can be dispensed with.

[0017] Preferably, the support layer further comprises a first polymer and a slip masterbatch.

[0018] Preferably, the homopolymer polypropylene barrier layer further comprises a nucleating masterbatch.

[0019] Preferably, the nucleating masterbatch is a blended granulation material of polypropylene and 1-5 wt% (relative to the total content of the nucleating masterbatch). The addition of the nucleating masterbatch is beneficial to increasing the crystallization rate of homopolymer polypropylene during the molding process, refining the crystal size, and improving the temperature resistance, impact resistance, and barrier properties of homopolymer polypropylene.

[0020] Preferably, the heat-sealing layer, support layer, homopolymer polypropylene barrier layer, and composite layer account for 10-20%, 40-70%, 10-30%, and 10-20% of the CPP film thickness, respectively. As the layer ratio of the homopolymer polypropylene barrier layer increases, the elastic modulus of the CPP film increases significantly. However, when the layer ratio exceeds 30%, it affects the deep-drawing performance of the CPP film.

[0021] Preferably, the first polymer is one or both of block copolymer polypropylene and atactic polypropylene.

[0022] Preferably, the polyolefin elastomer is a propylene-based elastomer, which has good compatibility with the first polymer used and can improve the impact of uneven elastomer dispersion on drawing performance. More preferably, the polyolefin elastomer is a nanoscale dispersed propylene-based elastomer, which further improves the dispersibility and compatibility of the elastomer when blended with other raw materials, and improves the impact of uneven elastomer dispersion on drawing performance.

[0023] Preferably, the slip masterbatch is a blended granulation material of 6-10 wt% (relative to the total content of the slip masterbatch) of erucamide and polypropylene.

[0024] Due to the presence of the homopolymer polypropylene barrier layer, the erucamide added to the support layer will migrate unidirectionally to the heat-sealing layer over time to maintain the low coefficient of friction of the heat-sealing layer.

[0025] Preferably, the support layer comprises 60-80 wt% of a first polymer, 10-40 wt% of a polyolefin elastomer, and 1-5 wt% of a slip masterbatch; the homopolymer polypropylene barrier layer comprises 90-95 wt% homopolymer polypropylene and 5-10 wt% of a nucleating masterbatch.

[0026] Preferably, the heat-sealing layer comprises 70-85 wt% random copolymer polypropylene, 5%-20 wt% polyolefin elastomer, 1-5 wt% anti-stick masterbatch, and 1-5 wt% slip masterbatch. The random copolymer polypropylene has a melting point of 120-150°C and a melt index of 5-10.

[0027] Preferably, the anti-sticking masterbatch is a blended granulation material of 3-6 wt% (relative to the total content of the anti-sticking masterbatch) of anti-sticking particles and polypropylene.

[0028] Preferably, the anti-sticking particles are one of silicon dioxide, glass microspheres, or synthetic silicon.

[0029] Preferably, the composite layer comprises 80-90 wt% of one or more of random copolymer polypropylene, block copolymer polypropylene, and maleic anhydride modified polypropylene, and 10-20 wt% of polyolefin elastomer.

[0030] Preferably, the polyolefin elastomer added to the heat-sealing layer is a propylene-based elastomer with a melting point greater than 135°C, which improves the temperature resistance of the heat-sealing layer, reduces the deformation of the CPP film during the heat-sealing process, and maintains its mechanical properties.

[0031] The second objective of this invention is to provide an aluminum-plastic film for packaging soft-pack lithium batteries, comprising the aforementioned CPP film.

[0032] A third objective of the present invention is to provide a soft-pack lithium battery comprising the aforementioned aluminum-plastic film.

[0033] By implementing the above technical solution, the present invention has the following beneficial effects:

[0034] The CPP film provided by this invention improves the elastic modulus, barrier properties, and friction coefficient stability of the CPP film through optimization and improvement of its structure and raw material composition. As a result, the aluminum-plastic film produced using this CPP film has excellent electrolyte resistance, deep drawing performance, and anti-curling performance, resulting in high-quality soft-pack lithium batteries. Detailed Implementation

[0035] The present invention will be further described in detail below through specific embodiments.

[0036] It should be noted that the following embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

[0037] Example 1:

[0038] A CPP film for soft-pack lithium batteries comprises a heat-sealing layer, a support layer, a homopolymer polypropylene barrier layer, and a composite layer in sequence.

[0039] The heat-sealing layer primarily serves a sealing function and directly contacts the stamping die during stamping. The raw material composition includes 77 wt% random copolymer polypropylene, 20 wt% polyolefin elastomer, 2 wt% anti-stick masterbatch, and 1 wt% slip masterbatch. The random copolymer polypropylene has a melting point of 140°C and a melt index of 7, and the polyolefin elastomer is a propylene-based elastomer. The anti-stick masterbatch is a blend of 5 wt% silica and the balance polypropylene. The slip masterbatch is a blend of 10 wt% erucamide and the balance polypropylene.

[0040] The support layer provides the necessary mechanical strength to the CPP film. The raw material composition includes 50 wt% block copolymer polypropylene, 30 wt% random copolymer polypropylene, 17 wt% polyolefin elastomer, and 3 wt% slip masterbatch. The block copolymer polypropylene has a melting point of 165°C and a melt index of 2, while the random copolymer polypropylene has a melting point of 150°C and a melt index of 2. The polyolefin elastomer is a propylene-based elastomer. The slip masterbatch is a blended granulated material of 6 wt% erucamide and 94 wt% polypropylene.

[0041] The homopolymer polypropylene barrier layer prevents electrolyte penetration, controls the stability of the friction coefficient, and improves the elastic modulus of the CPP film. The homopolymer polypropylene barrier layer comprises 95 wt% homopolymer polypropylene and 5 wt% nucleating masterbatch. The homopolymer polypropylene has a melting point of 165°C. The nucleating masterbatch is a blended granulated material of 5 wt% α-nucleating agent and 95 wt% polypropylene.

[0042] The composite layer is used for bonding with the aluminum foil layer, and its raw material composition includes 92 wt% random copolymer polypropylene and 8 wt% propylene-based elastomer. The random copolymer polypropylene has a melting point of 145°C and a melt index of 5.

[0043] The raw materials for the heat-sealing layer, support layer, homopolymer polypropylene barrier layer, and composite layer are blended according to the above-mentioned proportions by weight, and CPP film is made by co-extrusion casting process. The thickness percentage of the four layers is set as follows: heat-sealing layer 15% : support layer 55% : homopolymer polypropylene barrier layer 20% : composite layer 10%.

[0044] Example 2-10

[0045] The composition of the heat-sealing layer, support layer, homopolymer polypropylene barrier layer and composite layer was adjusted. The composition of each embodiment is shown in Table 1 (except for the different compositions shown in Table 1, the rest are the same as in Example 1).

[0046]

[0047]

[0048] Example 11:

[0049] A CPP film for soft-pack lithium batteries comprises a heat-sealing layer, a support layer, a homopolymer polypropylene barrier layer, and a composite layer in sequence.

[0050] Based on Example 1, the thickness of the homopolymer polypropylene barrier layer was adjusted while the total thickness remained unchanged. The raw materials of the heat-sealing layer, support layer, homopolymer polypropylene barrier layer and composite layer were blended according to the above-required proportions by weight, and CPP film was made by co-extrusion casting process. The thickness percentage of the four layers was set as follows: heat-sealing layer 15% : support layer 45% : homopolymer polypropylene barrier layer 30% : composite layer 10%.

[0051] (Except for the thickness of the homopolymer polypropylene barrier layer, everything else is the same as in Example 1), and its related properties are tested.

[0052] Example 12:

[0053] A CPP film for soft-pack lithium batteries comprises a heat-sealing layer, a support layer, a homopolymer polypropylene barrier layer, and a composite layer in sequence.

[0054] Based on Example 1, the thickness of the homopolymer polypropylene barrier layer was adjusted while the total thickness remained unchanged. The raw materials of the heat-sealing layer, support layer, homopolymer polypropylene barrier layer and composite layer were blended according to the above-required proportions by weight, and CPP film was made by co-extrusion casting process. The thickness percentage of the four layers was set as follows: heat-sealing layer 15% : support layer 65% : homopolymer polypropylene barrier layer 10% : composite layer 10%.

[0055] (Except for the thickness of the homopolymer polypropylene barrier layer, everything else is the same as in Example 1), and its related properties are tested.

[0056] Example 13:

[0057] A CPP film for soft-pack lithium batteries comprises a heat-sealing layer, a support layer, a homopolymer polypropylene barrier layer, and a composite layer in sequence.

[0058] Based on Example 1, the content of nucleating masterbatch in the homopolymer polypropylene barrier layer was adjusted to 8 wt% and the content of α-nucleating agent was 5 wt% (except for the content of nucleating masterbatch, everything else was the same as in Example 1), and its related properties were tested.

[0059] Example 14:

[0060] A CPP film for soft-pack lithium batteries comprises a heat-sealing layer, a support layer, a homopolymer polypropylene barrier layer, and a composite layer in sequence.

[0061] Based on Example 1, the content of nucleating masterbatch in the homopolymer polypropylene barrier layer was adjusted to 10 wt% and the content of α-nucleating agent was 5 wt% (except for the content of nucleating masterbatch, everything else was the same as in Example 1), and its related properties were tested.

[0062] Comparative Example 1:

[0063] The difference from Example 1 is that no homopolymer polypropylene barrier layer is provided; instead, it consists only of a heat-sealing layer, a support layer, and a composite layer arranged sequentially. The layer ratios of the three layers are 15%:75%:10%.

[0064] Comparative Example 2:

[0065] The difference from Example 1 is that no support layer is provided; it only includes a heat-sealing layer, a homopolymer polypropylene barrier layer, and a composite layer arranged sequentially. The layer ratios of the three layers are 15%:75%:10%.

[0066] Comparative Example 3:

[0067] The difference from Example 1 is that the homopolymer polypropylene barrier layer comprises 80 wt% homopolymer polypropylene, 15 wt% propylene-based elastomer, and 5 wt% nucleating masterbatch. A polyolefin elastomer is also added.

[0068] Comparative Example 4:

[0069] The difference from Example 1 is that the homopolymer polypropylene in the barrier layer is replaced with block copolymer polypropylene. The homopolymer polypropylene barrier layer comprises 95% block copolymer polypropylene and 5% nucleating masterbatch. The block copolymer polypropylene has a melting point of 160°C and a melt flow index of 6.

[0070] Comparative Example 5:

[0071] The difference from Example 1 is that the homopolymer polypropylene in the barrier layer is replaced with random copolymer polypropylene. The homopolymer polypropylene barrier layer comprises 95% random copolymer polypropylene and 5% nucleating masterbatch. The random copolymer polypropylene has a melting point of 140°C and a melt flow index of 5.

[0072] The CPP membranes corresponding to Examples 1-5 and Comparative Examples 1-5 were tested for relevant properties. The test items and test results are shown in Table 1.

[0073] The above examples and comparative examples were produced using a multi-layer co-extrusion casting process. The casting film production line has four extruders. The formulation materials for each layer are fed into the hoppers of the four extruders respectively. The extruder temperature is set to 230℃-250℃, and the casting roll temperature is set to 30-40℃. CPP films with a thickness of 80μm are produced according to the required layer ratio. At the same time, relevant performance items are compared and tested.

[0074] I. The barrier performance of CPP membranes was compared, mainly by testing the water vapor transmission rate and oxygen transmission rate of CPP membranes.

[0075] Water vapor transmission rate was tested using an infrared-based moisture permeation meter, and oxygen transmission rate was tested using an oxygen permeation meter. The test results are shown in Table 2.

[0076] Table 2. Test results of water vapor transmission rate and oxygen transmission rate of CPP membrane.

[0077]

[0078] Comparative testing of the moisture and oxygen permeability data of CPP membrane samples produced using the above methods reveals that the barrier performance of the CPP membrane significantly improves with increasing homopolymer polypropylene barrier layer layer ratio. The barrier performance also improves with increasing nucleating masterbatch weight ratio, but the increase becomes limited after reaching a certain point. Removing the homopolymer polypropylene barrier layer or replacing it with random or block copolymer polypropylene significantly reduces barrier performance. Adding polyolefin elastomers to the homopolymer polypropylene barrier layer also significantly reduces barrier performance.

[0079] II. Comparative Testing of the Friction Coefficient of CPP Films: Using a friction coefficient tester, the changes in the friction coefficient of the samples after production were tested under the same temperature and humidity conditions for different effective times. The test results are shown in Table 3.

[0080] Table 3 Test results of friction coefficient of CPP film

[0081]

[0082]

[0083] Friction coefficient comparison tests revealed that a higher layer ratio in the homopolymer polypropylene barrier layer, or an increase in the proportion of nucleating masterbatch, improved barrier performance and better barrier properties against slip agents. As the slip agent migrated to the heat-sealing layer, the friction coefficient of the heat-sealing layer continuously decreased, while the friction coefficient of the composite layer remained relatively stable. The change rates of the immediate friction coefficient and the surrounding friction coefficient were: dynamic friction coefficient change rate <31%, static friction coefficient change rate <34%, which has a beneficial effect on the later performance of the aluminum-plastic film. The elastic modulus of the CPP film was also compared. The elastic modulus of the aged CPP film was tested using an electronic tensile testing machine; the test results are shown in Table 4.

[0084] Table 4. Elastic modulus test results of CPP film

[0085]

[0086] The comparison of elastic modulus data shows that the elastic modulus increases significantly with the increase of the homopolymer polypropylene barrier layer layer ratio. In Comparative Example 2, the elastic modulus reaches its maximum when the homopolymer polypropylene barrier layer layer ratio reaches 60%. In Comparative Example 3, the addition of polyolefin elastomer reduces the elastic modulus of the film. From the perspective of the main materials, the elastic modulus shows a sequence of homopolymer polypropylene > block polypropylene > atactic polypropylene. However, considering the film's deep-drawing performance, the homopolymer polypropylene barrier layer layer ratio cannot be increased indefinitely, otherwise it will cause problems such as whitening and cracking during deep-drawing.

[0087] To further verify the beneficial properties of the aluminum-plastic film produced by this invention, aluminum-plastic film samples were made by composite process using CPP film produced by this method, nylon, and aluminum foil. Comparative drawing depth test and anti-curling test were conducted. The curling test results are shown in Table 5, and the drawing depth test results are shown in Table 6.

[0088] Table 5. Anti-curling test results of aluminum-plastic film samples made from CPP films of the examples and comparative examples.

[0089]

[0090]

[0091] ◎ indicates no curl, ○ indicates slight curl, and △ indicates curl.

[0092] The data above shows that the introduction of homopolymer polypropylene can effectively improve the elastic modulus of CPP film, and the improvement of the elastic modulus of CPP film can effectively improve the problem of deep-cutting curling of aluminum-plastic film.

[0093] Table 6. Draw depth test results of aluminum-plastic film samples made from CPP films used in the examples and comparative examples.

[0094]

[0095] ◎ indicates no whitening, ○ indicates slight whitening, and △ indicates whitening.

[0096] The data above shows that increasing the thickness of the homopolymer polypropylene barrier layer improves the elastic modulus and barrier properties of CPP, but it also causes whitening during deep drawing of the CPP film. According to the present invention, controlling the thickness ratio of the homopolymer polypropylene barrier layer to below 30% can effectively control the whitening problem of CPP film during deep drawing, while also considering both the barrier properties and elastic modulus of the CPP film, thus bringing beneficial performance effects to the finished aluminum-plastic film.

Claims

1. A CPP film for soft pack lithium battery packaging, comprising a heat-seal layer and a composite layer as two side faces, characterized in that, Further comprising a support layer adjacent to the inner side of the heat-seal layer, and a homopolypropylene barrier layer without polyolefin elastomer adjacent to the support layer and the composite layer, the support layer comprising 60-80 wt % of the first polymer, 10-40 wt % of the polyolefin elastomer and 1-5 wt % of the slip masterbatch, the sum of the percentages of the components of the support layer being 100 %; the homopolypropylene barrier layer comprising 90-95 wt % of the homopolypropylene and 5-10 wt % of the nucleating masterbatch, the nucleating masterbatch being a blend of 1-5 wt % of the alpha nucleating agent with respect to the total content of the nucleating masterbatch and polypropylene. 2.The CPP film for soft-pack lithium battery packaging according to claim 1, characterized in that, The heat-seal layer, the support layer, the homopolypropylene barrier layer, the composite layer account for 10-20 %, 40-70 %, 10-30 %, 10-20 % of the thickness of the CPP film in sequence. 3.The CPP film for soft-pack lithium battery packaging according to claim 1, characterized in that, The polyolefin elastomer is a propylene-based elastomer. 4.The CPP film for soft-pack lithium battery packaging according to claim 1, characterized in that, The first polymer is one or more of block copolymerized polypropylene, random polypropylene. 5.The CPP film for soft-pack lithium battery packaging according to claim 1, characterized in that, The slip masterbatch is a blend of 6-10 wt % of the erucamide with respect to the total content of the slip masterbatch and polypropylene.

6. An aluminum laminate film characterized by comprising: A soft package lithium battery packaging CPP film comprising any one of claims 1-5.

7. A pouch lithium battery, characterized by, An aluminum-plastic film comprising claim 6.

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