SUMMARY In this study, multiwall carbon nanotube (MWCNT) based buckypapers were produced via vacuum filtration techniques. The surfaces of the buckypapers were then coated with tin oxide (SnO2) thin films via radio frequency magnetron sputtering techniques. In order to evaluate the electrochemical performance of SnO2 coated buckypapers, bare SnO2 thin films were also deposited onto stainless steel substrates. Bare SnO2 was deposited on the stainless steel coin and on the functionalized MWCNT buckypapers. The SnO2/MWCNT nanocomposites have shown to exhibit desirable electrochemical performances as the negative electrodes for the lithium‐ion batteries. MWCNTs not only suppressed the mechanical degradation of SnO2 and, therefore, provided the composite electrode with excellent capacity retention (>700 mAhg−1 after 100 cycles) but also enhanced the electronic conductivity of the electrodes leading to excellent rate capability. The gradient composition of SnO2 from the surface to the center of the buckypaper in the SnO2/MWCNT nanocomposites has been shown to be critical for mitigating the mechanical degradation of electrodes. A nanocomposite produced at 5% O2 + 95 Ar atmosphere gave the best performance, exhibiting significantly high reversible capacity and excellent cycling ability. The excellent lithium storage and rate capacity performance of gradient composition SnO2/MWCNT core‐shell nanocomposites make them promising anode materials for lithium‐ion batteries. Copyright © 2013 John Wiley & Sons, Ltd.

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SUMMARYIn this study, SnO 2 :Sb coating on Cr-coated stainless steel and multiwall carbon nanotube (MWCNT) buckypaper substrates were prepared as anode materials using a radio frequency (RF) magnetron sputtering process for lithium-ion batteries. The nanocomposites were characterized with field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction and electrochemical test facilities. The evaluation of the electrochemical performance in lithium-ion batteries showed that the SnO 2 :Sb-MWCNT nanocomposites have shown reversible discharge capacities of 701 mAh g À1 , 732 mAh g À1 and 753 mAh g À1 for different RF powers (75 W, 100 W and 125 W), respectively, after 100 cycles. The high-capacity retention and cyclability ascribed to the good dispersion, high conductivity and fine particle size of SnO 2 :Sb on MWCNTs. Besides, the MWCNTs in SnO 2 :Sb act as a load carrying buffer component and behave like a flexible reinforcement, alleviating the electrode dilapidation resulted from volume change during the lithium insertion and de-insertion.

In the present study, we report the systematic investigation of the effect of chemical oxidation on the structure of multi-walled carbon nanotubes (MWCNTs) and multi-walled carbon nanotubes buckypaper. The chemical oxidation of multi-walled carbon nanotubes was performed via using three types of chemical solutions: nitric acid, sulfuric acid/nitric acid (3/1) and ammonium hydroxide/hydrogen peroxide (1/1). The surfaces of the multi-walled carbon nanotubes were modified by forming Carboxyl and other functional groups. Flexible multi-walled carbon nanotubes buckypapers were then produced by vacuum filtration techniques from functionalized multi-walled carbon nanotubes. The characteristic properties of multi-walled carbon nanotubes specimens were investigated via Raman, and Fourier Transform Infrared Spectroscopies. The thermal properties and morphology of multi-walled carbon nanotubes were also studied byThermogravimetric Analysis and Field Emission Scanning Electron Microscopy techniques.

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