The Study Of The Microcomputerized Electrochemical Measurement Method

On recent twenty years, coupled with the rapid development of PC and electronic technique, electrochemical analysis measuring machines in domestics has progressed much. However, on the whole there are some differences between electrochemical analysis and measurement machines in the world. Hence, in this dissertation, the electrochemical measurement methods have been studied and a simple system for electrochemical impedance spectrum (EIS) has been designed and the general program of electrochemical measurement software has been written.With object-oriented program-design of Visual Basic, an automatically EIS measurement system has been designed including PC, high speed A/DD/A transducer and potentiostat. It can output the sine wave, collect and analyze the data at high speed, save the data and display plots for punctual. It also has friendly user-computer interface such as the application programs of Windows and has frame based on the pull-down menus of Chinese character , pop-out window , mouse, hot key and so on.The electrochemical measurement methods have been investigated by Direct comparative fitting method(DCF), Lissayou fitting method(Lissayou), fast fourier transform method (FFT). Program test indicates that the experimental values accord with the theoretical values over a range of frequencies(0.01Hz-312.1Hz) at 0V potential applied to a working electrode and the measurement error is below 5%. The impedance measurement system had better accuracy, reliability and stability. From the EIS, the properties and characteristics of the electrochemical system can be judged elementarily.Direct comparative fitting method makes use of the Davidon arithmetic to calculate the impedance. This method was successful to be applied to impedance measurement for the first time and was tested theoritically and experimentally. Test shows the availability of the Direct comparative fitting method, which provides a new method of microcompurized impedance measurement quickly and accurately. Lissayou fitting method adopts the nonlinear least-square technique to calculate the impedance. Test shows good stability and validity, which is better impedance measurement method. In addition, the influences of FFT on measurement was discussed and after two mode test(single and multi-frequency). FFT is considered as an effective method to improve the velocity of measurement impedance at lower frequency. Finally, on the base of the developed charge-discharge battery software, its functions were perfected with Visual Basic. The copy of graphics, the print set , print position set , print preview and print of graphics are realized. Further, the chart of charge-discharge can be copied and printed.