PVDF (Polyvinylidene Fluoride) material for battery piece bearing tool and preparation method thereof
By synergistically reinforcing PVDF resin and surface-modified carbon fiber, a solar cell support fixture with high load-bearing strength and thermal stability was prepared, solving the problem of insufficient rigidity of PVDF material and improving the manufacturing quality and efficiency of photovoltaic modules.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-04
- Publication Date
- 2026-04-03
AI Technical Summary
In current photovoltaic module manufacturing, the rigidity and load-bearing capacity of PVDF materials are insufficient, causing bending or shading of the cells during the coating process, which affects product quality and performance.
PVDF composite masterbatch was prepared by mixing PVDF resin with surface-modified carbon fiber, followed by high-speed mixing, ultrasonic dispersion, and melt blending using a twin-screw extruder. This masterbatch was then combined with a hollow support frame and a nano-SiO2-modified PVDF coating to form a battery cell support tooling.
It improves the load-bearing strength and thermal stability of the battery cell support fixture, reduces stress defects caused by thermal expansion and contraction, and enhances the overall quality of the battery cells.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of photovoltaic module manufacturing technology, specifically relating to a PVDF material for battery cell support fixtures and its preparation method. Background Technology
[0002] In the manufacturing process of photovoltaic modules, the cell support fixture is a key process equipment, and its performance directly affects product quality and production efficiency.
[0003] Currently, there are two main support solutions on the market: one is a fully enclosed edge support structure, and the other is a four-corner support structure. While the traditional fully enclosed edge support fixture provides stable support, its large contact area with the solar cells can easily cause shading during processes such as coating, resulting in "black edges" or "black corners" on the cells, severely affecting the aesthetics and performance of the photovoltaic cells. On the other hand, while the four-corner support fixture reduces the contact area, when handling large silicon wafers (such as the currently mainstream 182mm and 210mm wafers), insufficient support points can easily lead to bending due to the weight of the wafer itself, resulting in uneven coating and affecting product yield.
[0004] Furthermore, from a materials perspective, most existing photovoltaic tooling is made of metal. While metal tooling has high structural strength, it suffers from problems such as heavy weight, high cost, and susceptibility to corrosion. PVDF material has excellent chemical corrosion resistance and high purity with no precipitation, making it the preferred material for transporting high-purity chemicals. Its high heat distortion temperature also meets the requirements for coating. However, due to its lower rigidity and load-bearing capacity compared to metal, it may undergo slow deformation when supporting large-area thin solar cells.
[0005] Therefore, overcoming the shortcomings of PVDF materials in terms of rigidity and load-bearing capacity in supporting solar cells is a technical problem that urgently needs to be solved in this field.
[0006] It should be noted that the information disclosed in this background section is only for understanding the background technology of this application concept, and therefore, the above description is not considered to constitute prior art information. Summary of the Invention
[0007] This disclosure provides at least one PVDF material for battery cell support fixtures and its preparation method.
[0008] In a first aspect, embodiments of this disclosure provide a PVDF material for a battery cell support fixture, comprising the following components by mass parts: 70-75 parts of PVDF resin and 10-15 parts of surface-modified carbon fiber; wherein the PVDF resin comprises 20-40 parts of high melt index resin and 60-80 parts of low melt index resin.
[0009] In one alternative embodiment, the surface-modified carbon fiber is a carboxylated carbon fiber.
[0010] In one alternative embodiment, the length of the carboxylated carbon fiber is 50–200 μm.
[0011] In one optional embodiment, the high melt index resin has a melt index range of 10–30 g / 10 min and 230 °C / 5 kg; the low melt index resin has a melt index range of 2–8 g / 10 min and 230 °C / 5 kg.
[0012] Secondly, this disclosure also provides a method for preparing PVDF material for battery cell support tooling as described above, including the following steps: S1, pretreatment, taking each component according to the mass fraction, mixing at high speed and ultrasonically dispersing to obtain a premix; S2, melt blending and granulation, melting and blending the premix through a twin-screw extruder, and granulating to obtain PVDF composite masterbatch, i.e., PVDF material for battery cell support tooling.
[0013] In one optional embodiment, the preparation method of the surface-modified carbon fiber includes the following steps: S11, washing the carbon fiber with acetone or ethanol under reflux, and then drying it to constant weight in a vacuum oven at 80°C; S12, mixing concentrated sulfuric acid and concentrated nitric acid at a volume ratio of 3:1, adding the pretreated dried carbon fiber to the mixed acid solution, wherein the mass ratio of carbon fiber to mixed acid solution is 1:50 to 1:100, the reaction temperature is 60 to 80°C, and the mixture is continuously stirred and refluxed; S13, washing and drying the carbon fiber after complete carboxylation reaction.
[0014] In one optional embodiment, the ultrasonic dispersion power in step S1 is 500-800W, and the mixing time is 20-40min; in step S2, the temperature of the feeding section of the twin-screw extruder is 180-185℃, the temperature of the melting section is 190-200℃, the temperature of the mixing section is 195-205℃, and the temperature of the homogenization section is 190-200℃; and the screw speed of the twin-screw extruder is 200-400rpm, and the ratio of the feeding speed to the screw speed is 0.3-0.6.
[0015] Thirdly, this disclosure also provides a PVDF cell support fixture, comprising: a support frame and a functional coating; wherein the support frame is a hollow structure and is made of PVDF material as described above for cell support fixtures; the functional coating is a nano-SiO2 modified PVDF coating with a coating thickness of 10-20 μm.
[0016] Fourthly, this disclosure also provides a method for preparing a PVDF cell support fixture as described above, comprising: preparing a support frame from PVDF composite masterbatch by hot pressing; and surface treatment, coating a layer of nano-SiO2 modified PVDF coating on the surface of the support frame to obtain the PVDF cell support fixture.
[0017] In one optional embodiment, the hot pressing includes magnetic field-assisted orientation to control the arrangement direction of surface-modified carbon fibers in the support frame; the magnetic field strength of the magnetic field-assisted orientation is 300-500 mT.
[0018] The beneficial effects of this invention are that the PVDF material used in the solar cell support tooling is reinforced by the synergistic effect of PVDF resin and carbon fiber, which significantly reduces the weight of the tooling while ensuring the load-bearing strength. At the same time, the inherent weather resistance of PVDF material combined with the thermal stability effect of carbon fiber enables the tooling to work stably for a long time in the high-temperature coating environment during the manufacturing process of photovoltaic modules. In addition, by modifying the carbon fiber, the coefficient of thermal expansion of the tooling can be adjusted to be similar to that of the solar cell, reducing stress defects caused by thermal expansion and contraction, and effectively improving the overall quality of the solar cell.
[0019] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description.
[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.
[0023] In this document, as used herein, expressions such as “at least one of…” modify the entire list of elements when following a list of elements, rather than individual elements in the list. For example, the expression “at least one of a, b, and c” should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.
[0024] The terminology used herein is for the purpose of describing specific exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may also be intended to include plural forms unless otherwise clearly stated herein. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. Additional or alternative steps may be employed.
[0025] The following describes some embodiments of the present invention in detail. Unless otherwise specified, the following embodiments and features can be combined with each other.
[0026] This disclosure provides a PVDF material for battery cell support fixtures, comprising the following components by mass: 70-75 parts of PVDF resin and 10-15 parts of surface-modified carbon fiber; wherein the PVDF resin comprises 20-40 parts of high melt index resin and 60-80 parts of low melt index resin.
[0027] In some embodiments, specifically, the surface-modified carbon fiber is carboxylated carbon fiber, and the carboxyl (-COOH) functional groups introduced on its surface can significantly increase its solubility, dispersibility, and compatibility in the PVDF resin matrix. This solves the core problem of carbon fiber's tendency to agglomerate, ensuring its uniform distribution in the matrix and effectively exerting its reinforcing effect.
[0028] In some embodiments, specifically, the length of the carboxylated carbon fiber is 50–200 μm.
[0029] In some embodiments, specifically, the melt index range of the high melt index resin is 10-30 g / 10 min, 230℃ / 5 kg; the melt index range of the low melt index resin is 2-8 g / 10 min, 230℃ / 5 kg. The mixed use of high and low melt index resins can improve the mixing uniformity of fibers while ensuring the fluidity of the resin itself.
[0030] This disclosure also provides a method for preparing PVDF material for battery cell support tooling as described above, including the following steps: S1, pretreatment, taking each component according to the mass fraction, mixing at high speed and ultrasonically dispersing to obtain a premix; S2, melt blending and granulation, melting and blending the premix through a twin-screw extruder, and granulating to obtain PVDF composite masterbatch, i.e., PVDF material for battery cell support tooling.
[0031] In some embodiments, the specific method for preparing the surface-modified carbon fiber includes the following steps: S11, washing the carbon fiber with acetone or ethanol under reflux, and then drying it to constant weight in a vacuum oven at 80°C; S12, mixing concentrated sulfuric acid and concentrated nitric acid at a volume ratio of 3:1, adding the pretreated dried carbon fiber to the mixed acid solution, wherein the mass ratio of carbon fiber to mixed acid solution is 1:50 to 1:100, the reaction temperature is 60 to 80°C, and the mixture is continuously stirred and refluxed; S13, washing and drying the carbon fiber after complete carboxylation reaction.
[0032] In some embodiments, specifically, in step S1, the ultrasonic dispersion power is 500–800 W, and the mixing time is 20–40 min; in step S2, the temperature of the feeding section of the twin-screw extruder is 180–185 °C, the temperature of the melting section is 190–200 °C, the temperature of the mixing section is 195–205 °C, and the temperature of the homogenization section is 190–200 °C; and the screw speed of the twin-screw extruder is 200–400 rpm, and the ratio of the feeding speed to the screw speed is 0.3–0.6.
[0033] This disclosure also provides a PVDF cell support fixture, comprising: a support frame and a functional coating; wherein the support frame is a hollow structure and is made of PVDF material as described above for cell support fixtures; the functional coating is a nano-SiO2 modified PVDF coating with a coating thickness of 10-20 μm.
[0034] This disclosure also provides a method for preparing a PVDF cell support fixture as described above, comprising: preparing a support frame from PVDF composite masterbatch by hot pressing; and surface treatment, coating a layer of nano-SiO2 modified PVDF coating on the surface of the support frame to obtain the PVDF cell support fixture.
[0035] In some embodiments, specifically, the hot pressing includes magnetic field-assisted orientation to control the arrangement direction of surface-modified carbon fibers in the support frame, so that the carbon fibers are oriented along the bearing grid direction to form anisotropic thermal / electrical conduction paths, which optimizes the thermal management and static dissipation path of the tooling during use; the magnetic field strength of the magnetic field-assisted orientation is 300-500mT.
[0036] Example 1: The PVDF material used for the battery cell support fixture comprises the following components by mass parts: 72 parts PVDF resin and 13 parts surface-modified carbon fiber; The PVDF resin includes 33 parts of high melt index resin with a melt index of 25 g / 10 min and 230 °C / 5 kg and 67 parts of low melt index resin with a melt index of 5 g / 10 min and 230 °C / 5 kg.
[0037] The preparation method of PVDF material for solar cell support fixtures includes the following steps: S1, Pretreatment: Take PVDF resin and surface-modified carbon fiber according to the mass fraction, mix them at high speed and disperse them ultrasonically to obtain a premix; S2, melt blending and granulation, involves melting and blending the premixed material through a twin-screw extruder and then pelletizing it to obtain PVDF composite masterbatch, which is the PVDF material used in battery cell support fixtures.
[0038] Specifically, in S1, the ultrasonic dispersion power is 500W and the duration is 30min; in S2, the feeding speed is 15 kg / h and the screw speed is 300 rpm (filling degree = 15 / 300 = 0.5).
[0039] Temperature profile: Feeding section 183℃, Melting section 195℃, Mixing section 200℃, Homogenization section 195℃.
[0040] The method for preparing the surface-modified carbon fiber includes the following steps: S11, the carbon fiber is washed with acetone or ethanol under reflux and then dried in a vacuum oven at 80°C to constant weight; S12, mix concentrated sulfuric acid and concentrated nitric acid at a volume ratio of 3:1, add the pretreated dried carbon fiber to the mixed acid solution, the mass ratio of carbon fiber to mixed acid solution is 1:80, the reaction temperature is 70℃, and the mixture is continuously stirred and refluxed. S13 involves cleaning and drying the carbon fibers that have undergone complete carboxylation.
[0041] The carbon fiber is selected from 24K precursor fibers with a length of 100μm.
[0042] Example 2 uses the same process parameters as Example 1, except that the PVDF resin includes 20 parts of a high melt index resin with a melt index of 25 g / 10 min and 230 °C / 5 kg and 80 parts of a low melt index resin with a melt index of 5 g / 10 min and 230 °C / 5 kg.
[0043] Example 3 uses the same process parameters as Example 1, except that the PVDF resin includes 40 parts of a high melt index resin with a melt index of 25 g / 10 min and 230 °C / 5 kg and 60 parts of a low melt index resin with a melt index of 5 g / 10 min and 230 °C / 5 kg.
[0044] Example 4 uses the same process parameters as Example 1, except that the carbon fiber used is 48K precursor fiber with a length of 100μm.
[0045] Example 5 uses the same process parameters as Example 1, except that the feeding speed is increased to 18 kg / h and the screw speed is maintained at 300 rpm (filling degree = 0.6).
[0046] Example 6 uses the same process parameters as Example 1, except that the feeding speed is reduced to 9 kg / h and the screw speed is maintained at 300 rpm (filling degree = 0.3).
[0047] Comparative Example 1 The process parameters are the same as in Example 1, except that the carbon fiber is not modified.
[0048] Comparative Example 2 The process parameters are the same as in Example 1, except that the PVDF resin used is a high melt index resin with a melt index of 25g / 10min and a temperature of 230℃ / 5kg.
[0049] Comparative Example 3 The process parameters are the same as in Example 1, except that the PVDF resin used is a low melt index resin with a melt index of 5g / 10min and 230℃ / 5kg.
[0050] Comparative Example 4 The process parameters are the same as in Example 1, except that the feeding speed is 6 kg / h and the screw speed is 300 rpm (filling degree = 0.2).
[0051] Specifically, the test performance data of Examples 1-6 and Comparative Examples 1-4 are shown in Table 1 below.
[0052] Table 1
[0053] Specifically, in Examples 1-3, Example 1 uses a mixture of high and low melt index resins to balance flowability and strength. In Example 2, the content of high melt index is lower than that in Example 1, resulting in a slight decrease in flowability and a slight decrease in flexural strength and HDT. In Example 3, the content of high melt index is higher than that in Example 1, resulting in better processing flowability, more uniform carbon fiber dispersion, and a slight increase in flexural strength and HDT.
[0054] Specifically, Example 4 uses 48K filament (thicker fiber bundles), which has higher fiber density, more significant reinforcement effect, improved bending strength, and reduced coefficient of thermal expansion (enhanced fiber orientation).
[0055] Specifically, Example 5 has a higher filling degree and a faster feeding speed, resulting in less uniform carbon fiber dispersion than Example 1 and a slight decrease in strength; Example 6 has a slower feeding speed, resulting in more thorough shearing of the fibers, better dispersion, and performance close to that of Example 1.
[0056] Specifically, in Comparative Example 1, the carbon fiber was not carboxylated, resulting in poor interfacial bonding with PVDF and easy agglomeration, which led to a significant decrease in flexural strength and HDT, and an increase in the coefficient of thermal expansion.
[0057] Specifically, Comparative Example 2 only uses high melt index resin, which has a low molecular weight, insufficient matrix strength, and significantly reduced flexural strength and HDT; Comparative Example 3 only uses low melt index resin, which has poor processing fluidity and makes carbon fiber dispersion difficult.
[0058] Specifically, in Comparative Example 4, the feeding speed was too slow (filling degree 0.2), the resin residence time was too long, causing partial degradation and a general decline in performance.
[0059] In summary, the PVDF material used in the solar cell support fixture is reinforced by the synergistic effect of PVDF resin and carbon fiber, which significantly reduces the weight of the fixture while ensuring its load-bearing strength. At the same time, the inherent weather resistance of PVDF material combined with the thermal stability effect of carbon fiber enables the fixture to work stably for a long time in the high-temperature coating environment during the photovoltaic module manufacturing process. In addition, by modifying the carbon fiber, the coefficient of thermal expansion of the fixture can be adjusted to be similar to that of the solar cell, reducing stress defects caused by thermal expansion and contraction, and effectively improving the overall quality of the solar cell.
[0060] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.
Claims
1. A PVDF material for a battery cell support fixture, characterized in that, It includes the following components by mass parts: 70-75 parts PVDF resin, 10-15 parts surface-modified carbon fiber; The PVDF resin comprises 20-40 parts of high melt index resin and 60-80 parts of low melt index resin.
2. The PVDF material for the battery cell support fixture as described in claim 1, characterized in that, The surface-modified carbon fiber is a carboxylated carbon fiber.
3. The PVDF material for the battery cell support fixture as described in claim 2, characterized in that, The length of the carboxylated carbon fiber is 50–200 μm.
4. The PVDF material for the battery cell support fixture as described in claim 1, characterized in that, The melt index range of the high melt index resin is 10-30 g / 10 min, 230℃ / 5 kg; The melt index range of the low melt index resin is 2-8 g / 10 min, 230℃ / 5 kg.
5. A method for preparing PVDF material for a battery cell support fixture as described in any one of claims 1-4, characterized in that, Includes the following steps: S1, Pretreatment: Take PVDF resin and surface-modified carbon fiber according to the mass fraction, mix them at high speed and disperse them ultrasonically to obtain a premix; S2, melt blending and granulation, involves melting and blending the premixed material through a twin-screw extruder and then pelletizing it to obtain PVDF composite masterbatch, which is the PVDF material used in battery cell support fixtures.
6. The preparation method according to claim 5, characterized in that, The method for preparing the surface-modified carbon fiber includes the following steps: S11, the carbon fiber is washed with acetone or ethanol under reflux and then dried in a vacuum oven at 80°C to constant weight; S12, mix concentrated sulfuric acid and concentrated nitric acid at a volume ratio of 3:1, add the pretreated dried carbon fiber to the mixed acid solution, the mass ratio of carbon fiber to mixed acid solution is 1:50 to 1:100, the reaction temperature is 60 to 80℃, and the mixture is continuously stirred and refluxed. S13 involves cleaning and drying the carbon fibers that have undergone complete carboxylation.
7. The preparation method according to claim 5, characterized in that, In step S1, the ultrasonic dispersion power is 500-800W, and the mixing time is 20-40min. In step S2, the temperature of the feeding section of the twin-screw extruder is 180-185℃, the temperature of the melting section is 190-200℃, the temperature of the mixing section is 195-205℃, and the temperature of the homogenization section is 190-200℃. Furthermore, the screw speed of the twin-screw extruder is 200-400 rpm, and the ratio of the feeding speed to the screw speed is 0.3-0.
6.
8. A PVDF solar cell support fixture, characterized in that, include: Support frame and functional coating; The supporting frame is a hollow structure and is made of PVDF material for battery cell support tooling as described in any one of claims 1-4. The functional coating is a nano-SiO2 modified PVDF coating with a thickness of 10–20 μm.
9. A method for preparing a PVDF cell support fixture as described in claim 8, characterized in that, include: PVDF composite masterbatch was prepared into a support framework by hot pressing. Surface treatment involves coating the surface of the support frame with a layer of nano-SiO2 modified PVDF coating to obtain a PVDF cell support fixture.
10. The preparation method according to claim 9, characterized in that, The hot pressing process includes magnetic field-assisted orientation to control the orientation of surface-modified carbon fibers in the support frame. The magnetic field strength for the magnetic field-assisted orientation is 300–500 mT.