Electrochemical lithium Ion intercalation into and deintercalation from carbon electrodes prepared by plasma enhanced chemical vapour deposition method : corrosion fatigue of aluminium-based alloy

Abstract

The present work is concerned with electrochemical lithium ion intercalation into and deintercalation from carbon electrodes prepared by plasma enhanced chemical vapour deposition method and also with corrosion fatigue of aluminium-based alloy. In chapter III, electrochemical lithium transport through a plasma enhanced chemical vapor deposited (PECVD) carbon film electrode was investigated in 1M $LiPF_6$- ethylene carbonate (EC) and diethyl carbonate (DEC) solution during lithium intercalation and deintercalation, by using cyclic voltammetry supplemented with ac-impedance spectroscopy in reference to graphite powder electrode. Both the layer spacing and the size of the graphitic crystallite in the a- and c-axis directions obtained from the carbon film electrode were much smaller than those of the graphite one, indicating less-developed crystalline structure with hydrogen bonded to carbon, from the results of Auger electron spectroscopy (AES), powder X-ray diffraction (XRD) method, and Fourier transform infra-red (FTIR) spectroscopy. It was shown from the cyclic voltammograms and ac-impedance spectra of carbon film electrode that a threshold overpotential was needed to overcome an activation barrier to entrance of lithium into the carbon film electrode, such as the poor crystalline structure of the carbon film electrode showing disordered carbon and the presence of residual hydrogen in its structure. The experimental results were discussed in terms of the effect of host carbon structure on the lithium intercalation capability. In chapter IV, electrochemical lithium intercalation into PECVD carbon film electrodes was investigated in 1 M $LiPF_6-EC/DEC$ solution, by using ac-impedance spectroscopy supplemented with cyclic voltammetry. The carbon film electrodes were prepared at different deposition temperatures of 500˚, 600˚, and 700℃. The analyses of AES, powder XRD method, and FTIR spectroscopy showed that the carbon film electrodes had poorly crystallized struc...