A cathode device for testing high specific volume tantalum anode capacity comprises an export connection piece, a tantalum block assembly and a tantalum block fastener. The tantalum block fastener is arranged on the tantalum block assembly for fixing the tantalum block assembly firmly. The export connection piece is located on one side of the tantalum block assembly, and the lower half of the export connection piece is fixedly connected with the tantalum block assembly for connecting the entire cathode device with the capacity testing instrument. In the testing process, the average distance d between the anode area and the cathode area is always stable, so that the testing results of the capacity and loss are stable; The cathode surface area is twice as high as the surface area of the existing volume test cathode, and the high specific volume extraction rate meets the high specific volume tantalum powder test. The cathode structure has good contact, so that the average distance d between anode area and cathode area is always stable, and the capacity and loss test results are stable.
The specific surface area of cathode is a key factor affecting the capacity measurement of tantalum anode block. With the increase of the capacity of tantalum anode, the required cathode specific surface area increases correspondingly. When the specific surface area of cathode is large enough, the measured capacity of tantalum anode tends to be stable and close to the true value. As the specific volume of tantalum powder is improved, the specific area of the cathode used for testing is required to be large enough. However, the Pt black cathode used for testing currently (1) electroplating Pt black on platinum sheet has short service life and small surface area; (2) Ag-Ta cathode prepared by several tantalum powder pressed sintered blocks bound on silver sheet has complex structure and high loss, and the binding mode makes the tantalum block and silver sheet have poor contact.
The current volume test cathode used for testing consists of 17 tantalum sintered blocks. The cathode has a small surface area, resulting in a small opposite area S. When measuring tantalum anode with high specific volume, the specific volume extraction rate is low, which cannot meet the requirements of high specific volume tantalum powder test. In addition, due to the shape of the test cup, the cathode is only on one side of the test cup. During the test, the average distance d between the anode area and the cathode area is inconsistent with the different operating habits of the tester, resulting in unstable test results and loss value of capacitance C. The tantalum block as the cathode is bound to the silver sheet, resulting in poor contact and poor stability in the capacity test. Ag-Ta cathode made by several tantalum powder pressed sintered blocks bound on silver plate has poor cathode contact, large variation of the average distance d between anode area and cathode area, and unstable capacity and loss test results.
