Compósitos diamante-CVD/Fibra de carbono como ânodo em baterias de íons de lítio / DIAMOND/CARBON FIBER COMPOSITE AS ANODE IN LITHIUM ION BATTERIES

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

An innovative composite diamond/carbon fiber is presented for application as negative electrode (anode) in lithium ion batteries. In this sense, it was important the understanding and discussion of three subjects divided into: obtaining and characterization of the carbon fiber, used as substrate; growth and characterization of doped diamond film on the fiber, forming the composite; and, finally, the results of the application of this material as anode in lithium ion batteries. The structure of the carbon fibers obtained from polyacrylonitrile precursor is strongly dependent on the heat treatment temperature (HTT). HTT increasing affects the diamond film quality as well as the sample electrical resistivity and the intercalation sites. Morphological differences on the diamond films are also evident as a function of HTT. The grain size, observed from Scanning Electron Microscopy (SEM), increases with the evolution of the substrates graphitization treated at 1000, 1500 and 2000 °C. An more organized structure favored the appearance of the pyramidal (111) diamond plane where diamond particles possibly nucleated at the graphite edge. In all the studied substrate the SEM images show that the carbon fibers were completely re-covered by the diamond film, forming a three-dimensional diamond structure up to a depth of 1.5 mm, for films grown in both sample sides. The electrochemical behavior of lithium intercalation showed that the composite electrode with fibers treated at 1000 °C and re-covered with highly conducting diamond increases the capacity of lithium storage, when the intercalation process was made with low current, reaching 370 mA.h.g-1 of the reversible charge capacity. The main advantage of these composite electrodes is that they are free of a polymer binder, frequent ly used in the electrodes for lithium ion batteries. Thus, the batteries anode preparation becomes easy and simplified, further than to decrease the electric resistance in such device.

ASSUNTO(S)

compósito híbrido carbon fibers lithium batteries space engineering and technology hybrid composites baterias de lítio fibras de carbono armazenamento de energia filme de diamante engenharia e tecnologia espacial energy storage diamond films

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