Abstract:
A method for manufacturing a current collector layer is provided. The method comprises: forking a release layer on a surface of a film; forming an adhesive layer on the release layer; forming a metal layer on the adhesive layer; and removing the film and the release layer.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the priority benefit of TW application serial no. 105102583,filed on Jan. 27, 2016. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
       BACKGROUND OF THE INVENTION 
       [0002]    Field of the Invention 
         [0003]    The disclosure relates to a method for manufacturing a current collector layer and, more specifically, to a method for manufacturing a thin current collector layer. 
         [0004]    Description of the Related Art 
         [0005]    Generally, the operation mechanism of a battery is relied on redox reactions that generated between positive, negative electrodes and electrolytes, the formed circulatory system generates a current and functions as a battery. When the battery discharges, ions moves from the negative electrode to the positive electrode through the electrolytes. At the same time, electrons move to the positive electrode from an external circuit to generate current. The positive and negative electrodes are coated on a current collector layer. The current collector layer is served as a conductor for the electrons during the charging and discharging processes of the battery. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    According to an aspect of the disclosure, a method for manufacturing a current collector layer is provided. The method comprises: forming a release layer on a surface of a film; forming an adhesive layer on the release layer; forming a metal layer on the adhesive layer; and removing the film and the release layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    These and other features, aspects and advantages of the disclosure will become better understood with regard to the following embodiments and accompanying drawings. 
           [0008]      FIG. 1  is a flow chart of a method for manufacturing a current collector layer in an embodiment; 
           [0009]      FIG. 2A  to  FIG. 2D  are section views showing the process in manufacturing a current collector layer according to the flow chart in  FIG. 1  in an embodiment; and 
           [0010]      FIG. 3  is a flow chart of a method for manufacturing a current collector layer in an embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0011]    The invention is described accompanying with the figures. The invention may be implemented in different forms, and embodiments described hereinafter are not used for limiting the invention. For clarity, thickness of layers/areas shown in the figures is enlarged. 
         [0012]      FIG. 1  is a flow chart of a method for manufacturing a current collector layer in an embodiment.  FIG. 2A  to  FIG. 2D  are section views showing the process in manufacturing a current collector layer according to the flow chart in  FIG. 1  in an embodiment. 
         [0013]    Please refer to  FIG. 1  and  FIG. 2A , a method for manufacturing a current collector layer includes following steps. A film  100  is provided. In an embodiment, the material of the film  100  is one or a combination selected from the group consisting: polyethylene terephthalate (PET), polycarbonate (PC) and polymethyl methacrylate (PMMA), which is not limited herein. In an embodiment, the film  100  is made of other resin materials. In an embodiment, the thickness of the film  100  is between 50 μm˜300 μm. 
         [0014]    Then, in step S 100 , a release layer  104  is formed on a surface  102  of the film  100 . In an embodiment, the release layer  104  is formed by coating a release agent on the surface  102  of the film  100  and then drying the release agent. In an embodiment, the drying treatment is performed at a temperature of 25° C.˜70° C. As shown in  FIG. 2A , in an embodiment, the surface  102  is an upper surface of the film  100 , which is not limited herein. In another embodiment, the surface  102  is a lower surface of the film  100 . 
         [0015]    The release agent is one or a combination selected from the group consisting a fluorine-containing organic compound, a chlorine-containing polymer and a silicon-containing organic compound, which is not limited herein. In an embodiment, the fluorine-containing organic compound is one or a combination selected from the group consisting polytetrafluoroethene (PTEF), polyvinylidene difluoride (PVDF) and fluorinated ethylene propylene copolymer (FEP). In an embodiment, the chlorine-containing polymer is polyvinyl chloride (PVC). In an embodiment, the silicon-containing organic compound includes polyester and/or silicone resin. However, the material of the release agent is not limited herein. In an embodiment, any material with low surface energy that does not react easily with adjacent materials can be used as the release agent. 
         [0016]    Please refer to  FIG. 1 ,  FIG. 2A  and  FIG. 2B , then, step S 102  is selectively performed. A surface treatment is performed onto the surface  103  of the release layer  104  to make the surface of the release layer  104   a  roughened. In an embodiment, the surface treatment is one or a combination selected from the group consisting a plasma treatment, an ion source treatment and a spark treatment. In an embodiment, any surface treatment for roughening the surface of the release layer  104   a  can be used. 
         [0017]    In the embodiment, the surface energy of the surface  103  of the release layer  104   a  is increased and the surface  103  is roughened and uneven via the surface treatment onto the release layer  104  in step S 102 . Therefore, an adhesion force between the release layer  104   a  and an adhesive layer  106  (which is subsequently formed as shown in  FIG. 2C ) is increased via roughened surface  103  to avoid the detachment of the adhesive layer  106 . 
         [0018]    Please refer to  FIG. 1 ,  FIG. 2B  and  FIG. 2C , then, in step S 104 , the adhesive layer  106  is formed on the release layer  104   a.  In an embodiment, the adhesive layer  106  increases the adhesion force between the release layer  104   a  and the metal layer  108  (which is subsequently formed) to avoid the detachment of the metal layer  108 . In an embodiment, the material of the adhesive layer  106  includes silicon oxide and/or titanium oxide. In an embodiment, the thickness of the adhesive layer  106  is less than 0.1 μm and the adhesive layer  106  is formed via a dry deposition method. The dry deposition method includes a physical vapor deposition method and/or an atomic layer deposition. The physical vapor deposition method is sputtering, evaporation or e-Gun evaporation, which is not limited herein. In an embodiment, any dry deposition method at a processing temperature below 150° C. can be used. 
         [0019]    In the embodiment, the adhesive layer  106  is formed via the dry deposition method. The adhesion force between the adhesive layer  106  and the release layer  104   a  is increased via the roughened surface  103 . Thus, the thickness of the adhesive layer  106  is less than 0.1 μm to avoid a lower conductivity of the finished current collector layer. 
         [0020]    Then, please refer to  FIG. 1  and  FIG. 2C , in step S 106 , the metal layer  108  is formed on the adhesive layer  106 . The material of the metal layer  108  includes one or a combination selected from the group consisting copper, aluminum, nickel and tin. In an embodiment, the metal layer  108  is formed via a dry deposition method. The dry deposition method includes a physical vapor deposition (PVD) and/or an atomic layer deposition (ALD) The physical vapor deposition (PVD) includes sputtering, evaporation or e-Gun evaporation. In an embodiment, any dry deposition method at a processing temperature below 150° C. can be used. 
         [0021]    In an embodiment, the metal layer  108  is formed via a wet deposition method. The wet deposition method includes electroplating and/or chemical plating. When the metal layer  108  is formed by the wet deposition method, an activated layer is formed on the surface  105  of the adhesive layer  106  before the metal layer  108  is formed. The activated layer includes at least one metallic element used as a metal catalyst to accelerate the deposition of the metal layer  108 . In an embodiment, the activated layer is formed by using electrolytes including one or a combination selected from the group consisting palladium chloride, ruthenium chloride and thallium chloride to activate and sensitize the surface  105  of the adhesive layer  106 , and then the palladium (Pd), the ruthenium (Ru) or the thallium (Tl) is attached to the surface of the adhesive layer  106  to improve the conductivity and activity of the adhesive layer  106 . 
         [0022]    Problems of calendering effects of materials and limitations from the thickness of a rolling device are solved via the dry deposition method or the wet deposition method. Therefore, the thickness of the metal layer  108  is made less than 3 μm. In an embodiment, the thickness of the metal layer  108  is between 0.5 μm to 2.5 μm. 
         [0023]    Please refer to  FIG. 1 ,  FIG. 2C  and  FIG. 2D , in step S 108 , the film  100  and the release layer  104   a  are removed. After the film  100  and the release layer  104   a  are removed, the adhesive layer  106  and the metal layer  108  are left. The thinner the adhesive layer  106  (for example, less than 0.1 μm), the better the conductivity of the metal layer  108 . 
         [0024]    In the embodiment, the metal layer  108  is used as current collector layers of positive and negative electrodes in a battery unit. The positive and negative electrodes are stacked alternatively to form the battery. Therefore, in the embodiment, when the single metal layer  108  (as the current collector layer of either the positive electrode or the negative electrode) becomes thinner, the whole thickness of the stacked battery is reduced, and thus the available space of the battery is increased. In such a way, the efficiency of the battery is improved. 
         [0025]    In an embodiment, the material of the metal layer  108  is various for different types of the battery. In an embodiment, in a lithium ion battery, the current collector layer of the positive electrode is aluminum, and the current collector layer of the negative electrode is copper. The battery can be any type only if a potential difference (PD) exits between plate materials of the positive electrode and the plate materials of the negative electrode. In an embodiment, in a nickel-hydrogen battery, nickel is used as the material of the current collector layer of the positive electrode. 
         [0026]      FIG. 3  is a flow chart of a method for manufacturing a current collector layer in an embodiment. 
         [0027]    Please refer to  FIG. 1  and  FIG. 3 , in an embodiment, a method for manufacturing a current collector layer includes following steps. In step S 200 , the release layers are formed on two opposite sides of the film, respectively. Then, step S 202  is selectively performed, in which surface treatments are performed onto the two release layers. Then, in step S 204  and step S 206 , the adhesive layer is formed on each of the two release layers, respectively. Then, the metal layer is formed on each of the two adhesive layers, respectively. At last, in step S 208 , the film and the two release layers are removed to form two composite layers including the metal layer and the adhesive layer. Since the materials, the thickness and the forming methods of the film, the release layer, the adhesive layer and the metal layer are described above, which are not described herein. 
         [0028]    In sum, in embodiments, the metal layer is formed on the release layer via the dry deposition method or the wet deposition method, and thus the thickness of the metal layer is made less than 3 μm. Therefore, when the metal layer is used as the current collector layer of the battery, the whole thickness of the battery is reduced and the efficiency of the battery is improved. Furthermore, before the metal layer is formed, the adhesive layer is formed on the release layer to increase the metal adhesion force to avoid the detachment of the metal layer. 
         [0029]    Additionally, in an embodiment, the metal layers are formed on the opposite sides of the film, respectively. After the film and two release layers are removed, two separate composite layers each consisting of the metal layer and the adhesive layer are obtained. Therefore, the method for forming the metal layer reduces the cost. 
         [0030]    Although the disclosure has been disclosed with reference to certain embodiments thereof, the disclosure is not for limiting the scope. Persons having ordinary skill in the art may make various modifications and changes without departing from the scope of the disclosure. Therefore, the scope of the appended claims should not be limited to the description of the embodiments described above.