Cathode electrode for anodic oxidation of tantalum capacitor

Abstract

The utility model discloses a cathode electrode for anode oxidation of a tantalum capacitor, which comprises a main cathode electrode with a grid structure, a cathode auxiliary electrode is arranged on the periphery of the main cathode electrode, and materials of the cathode electrode and an anode electrode are kept consistent, so that potential difference caused by different electron transmission rates of the two electrodes can be reduced, and electrochemical polarization is reduced; the grid structure of the cathode electrode increases the area of the cathode and is beneficial to uniform distribution of anode current density, and the grid structure of the cathode electrode also reduces the surface tension between the cathode and the electrolyte and increases the contact area between the electrolyte and the cathode, so that the contact area during H < + > reduction reaction is increased; the cathode auxiliary electrode is added, the edge effect is reduced through the cathode auxiliary electrode, and the uniformity of electric field distribution between the cathode and the anode is improved.

Description

Technical Field

[0001] This utility model belongs to the field of tantalum capacitor technology, and specifically relates to a cathode electrode for anodic oxidation of tantalum capacitors. Background Technology

[0002] In a parallel-plate capacitor, the parallel-plate electrodes of finite length and width have a uniform electric field between the electrodes far from the edges. Near the edges, the electric field lines form a large shape outside the volume between the electrodes, the electric field distribution is no longer uniform, and there is an edge effect due to electric field distortion. The edge effect further enhances the electric field strength at the electrode edges, resulting in a non-uniform current density distribution.

[0003] Reference Figure 1 Currently, stainless steel perforated plate structures are still used as cathodes. Due to the small cathode area, the anodes around the perimeter change color first, resulting in a significant edge effect during the anodizing process and uneven current density distribution.

[0004] Chinese utility model patent CN208455080U discloses an adjustable cathode plate for a formation process, including an electrode plate support, a guide rail on the electrode plate support with a scale engraved on the guide rail, an electrode plate fitted on the guide rail, and sliders at both ends of the electrode plate. The sliders have guide rail holes and fastening holes, through which the guide rail passes. During production, the spacing between the electrode plates can be increased in the early stages of the reaction as needed, reducing the area directly facing the electrode and the etching foil, thereby effectively reducing the current density. It can also be flexibly adjusted according to the needs of process engineers when producing products of different specifications. This utility model has a simple structure, good stability, and is suitable for widespread use. While this solution reduces current density by increasing the spacing between the electrode plates, the added structure complicates the internal structure of the electrode, and the controllability of the guide rail is difficult to adjust. Utility Model Content

[0005] To address the aforementioned problems, this invention aims to provide a cathode electrode for the anodization of tantalum capacitors.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a cathode electrode for anodizing a tantalum capacitor, comprising a main cathode electrode with a grid structure, and a cathode auxiliary electrode disposed around the main cathode electrode;

[0007] The material used for the main cathode electrode is the same as that used for the anode electrode.

[0008] Furthermore, the cathode auxiliary electrode is made of tantalum powder.

[0009] Furthermore, the specific volume and size of the tantalum powder used to prepare the auxiliary electrode are determined based on the anode electrode. The specific volume of the tantalum powder in the cathode auxiliary electrode is consistent with that in the anode electrode. The radial dimension of the cathode auxiliary electrode is 1 times or more of that of the anode electrode. The shape of the cathode auxiliary electrode is a regular geometric shape such as rectangle, circle, or trapezoid.

[0010] Furthermore, the total CV product of the cathode auxiliary electrode is 0.5 times or more of that of the anode electrode.

[0011] Furthermore, the main cathode electrode is made of tantalum wire, and the diameter of the tantalum wire and the mesh count of the mesh are determined according to requirements.

[0012] Compared with the prior art, the present invention has the following advantages:

[0013] 1. Using the same material for the cathode electrode and the anode electrode can reduce the potential difference caused by the different electron transport rates of the two electrodes, thereby reducing electrochemical polarization;

[0014] 2. The mesh structure increases the cathode area, which is beneficial for the uniform distribution of anolyte current density, reduces the surface tension between the cathode and the electrolyte, increases the contact area between the electrolyte and the cathode, and thus increases Ha. + The contact area during the reduction reaction;

[0015] 3. Add a cathode auxiliary electrode to reduce edge effects and improve the uniformity of the electric field distribution between the cathode and anode. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a conventional cathode in this utility model;

[0018] Figure 2 This is a schematic diagram of the cathode electrode of the tantalum capacitor undergoing anodic oxidation in this utility model.

[0019] Figure 3 This is a schematic diagram showing the placement of the cathode electrode in an embodiment of this utility model;

[0020] In the figure, 1-main cathode electrode; 2-cathode auxiliary electrode. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. Any modifications, substitutions and alterations made based on ordinary technical knowledge and conventional means in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0022] Reference Figure 2 The cathode electrode of the tantalum capacitor anodized includes a main cathode electrode 1 with a grid structure and a cathode auxiliary electrode 2 arranged around the main cathode electrode. The material used for the main cathode electrode 1 is the same as that used for the anode electrode, which can reduce the potential difference caused by the different electron transport rates of the two electrodes and reduce electrochemical polarization.

[0023] The cathode auxiliary electrode 2 is made of tantalum powder. The specific volume and dimensions of the tantalum powder used to prepare the cathode auxiliary electrode 2 are determined based on the anode electrode. The specific volume of the tantalum powder in the cathode auxiliary electrode 2 is consistent with that in the anode electrode. The radial dimension of the cathode auxiliary electrode 2 is one time or more than that of the anode electrode. The shape of the cathode auxiliary electrode 2 is rectangular, circular, trapezoidal, or other regularly geometrically shaped electrodes. The total CV product of the cathode auxiliary electrode 2 is 0.5 times or more than that of the anode electrode.

[0024] By using a cathode auxiliary electrode, the edge effect can be reduced, and the uniformity of the electric field distribution between the cathode and anode can be improved.

[0025] The main cathode electrode 1 has a mesh structure made of tantalum wire. The diameter of the tantalum wire and the mesh count are determined according to requirements. The mesh structure increases the cathode area, which is beneficial for the uniform distribution of anolyte current density, reduces the surface tension between the cathode and the electrolyte, increases the contact area between the electrolyte and the cathode, and thus increases Ha. + The contact area during the reduction reaction.

[0026] Example: Tantalum wire with a diameter of 0.29 mm was made into a 20-mesh 40*40cm mesh as the main cathode electrode; tantalum powder with a specific volume of 40000 μF·V / g was shaped and sintered to obtain 36 circular bodies with a diameter of φ34*3mm, which were used as auxiliary cathode electrodes and placed closely around the edge of the main cathode electrode. Figure 3 As shown, the arrangement is a 10x10 rectangular configuration. Tantalum powder with a specific volume of 40000 μF·V / g was shaped and sintered to obtain 30 circular bodies with a diameter of φ34*3mm, which were then used as anode electrodes.

[0027] The total CV product of the cathode auxiliary electrode is: 36 * 40000 μF·V / g = 1440000 μF·V / g

[0028] The total CV product of the anode electrode is: 30 * 40000 μF·V / g = 1200000 μF·V / g

[0029] The total CV product of the cathode auxiliary electrode / the total CV product of the anode electrode = 1.2 times.

[0030] During the anodizing process, when the voltage at the anode electrode is boosted to 65V, an additional... Figure 1 The cathode plate shown exhibits color difference among its 30 anode electrodes. However, when using the cathode plate shown in the embodiment, there is no color difference among the 30 anode electrodes. The color difference results indicate that using the cathode plate of the embodiment improves the uniformity of the current density of the anode electrodes.

[0031] The foregoing has provided a detailed description of the cathode electrode for anodizing a tantalum capacitor according to this utility model. Specific examples have been used to illustrate the structure and working principle of this utility model. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core idea of ​​this utility model. It should be noted that those skilled in the art can make various improvements and modifications to this utility model without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of this utility model.

Claims

1. A cathode electrode for anodic oxidation of a tantalum capacitor, characterized in that: It includes a main cathode electrode (1) with a grid structure, and a cathode auxiliary electrode (2) is provided around the main cathode electrode (1); The material used for the main cathode electrode (1) is the same as that used for the anode electrode.

2. The cathode electrode of the tantalum capacitor anodic oxidation according to claim 1, characterized in that: The cathode auxiliary electrode (2) is made of tantalum powder.

3. The cathode electrode of the tantalum capacitor anodic oxidation according to claim 2, characterized in that: The specific volume and size of the tantalum powder used to prepare the cathode auxiliary electrode (2) are determined according to the anode electrode. The specific volume of the tantalum powder in the cathode auxiliary electrode (2) is consistent with that in the anode electrode. The radial dimension of the cathode auxiliary electrode (2) is 1 times or more of that of the anode electrode. The shape of the cathode auxiliary electrode (2) is a regular geometric shape, including but not limited to rectangle, circle and trapezoid.

4. The cathode electrode of the tantalum capacitor anodic oxidation according to claim 1, characterized in that: The total CV area of ​​the cathode auxiliary electrode (2) is 0.5 times or more of that of the anode electrode.

5. The cathode electrode of the tantalum capacitor anodic oxidation according to claim 1, characterized in that: The main cathode electrode (1) is made of tantalum wire, and the diameter of the tantalum wire and the mesh count of the screen are determined according to the requirements.

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