Desempenho eletroquímico de compósitos de nanotubos de carbono como anodos para baterias de íon-lítio
Bento, Fábio Ricardo
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In this work CNTs composite for use as Li-ion anode materials had been investigated. The electrochemical properties of the electrodes were measured by galvanostatic charge-discharge testes, cyclic voltammetric analysis and electrochemical impedance spectroscopy. The first materials was discussed were the NiO:MWNTs composite. Previously, NiO powders were prepared via the spray pyrolysis technique and, the NiO:MWNTs composite was prepared by dispersion simultaneously of MWNTs and NiO powders using ultrasonicator. The electrochemical properties of NiO:MWNTs composite were investigated to determine their suitability as anode materials for lithium-ion batteries. The NiO:MWNTs composite electrodes exhibited better reversibility and higher capacities than NiO and MWNTs electrodes. The reasons for improved electrochemical performance of the composite electrodes are discussed. Another composite had been investigated was C-SnO2-SWNTs. The C-SnO2-SWNTs composite powder was prepared by mechanical ball milling and [C-SnO2]- dSWNTs was synthesized by dispersion SWNTs via ultrasonication into a premilled C-SnO2 composite mixture. It was found that the cyclic performance of the both composite materials was improved when they was compared to CSnO2. Free-standing SWNT paper electrodes have been synthesized by a simple filtration. With addition of C-SnO2 composite powder was prepared by mechanical milling, the specific capacity of the free-standing ([CSnO2] 0.5SWNTs0.5) paper electrode were greatly enhanced, so that they retained a capacity of 310 mAh g-1 beyond 30 cycles. On the other hand, the procedures for SWNTs electrode preparation were simplified, so the cost of the manufacturing could be reduced. The specific capacities at 20th cycle decrease in the order: [C-SnO2]-dSWNTs > [C-SnO2]0.5SWNTs0.5 > C-SnO2-SWNTs > NiO:MWNTs (70:30) > C-SnO2 > NiO > MWNTs.