Electrochemical Properties of Tin Nanoparticles Encapsulated in Different Origin Carbon Buffer Matrix
The goal of the present work was development two types of carbon-tin nanocomposite anode materials and comparison of their electrochemical properties. In both cases the nanocomposites were obtained in a simple and inexpensive process, consisted of tin-based nanograins encapsulated in a flexible carbon buffer matrix derived from plant polysaccharides in the first series and from water soluble polymer in the latter.
The precursor of active material was obtained using a modified reverse microemulsion technique (w/o) and then coated by a source of carbon (potato starch or poly(N-vinylformamide) mixed with pyromellitic acid) [6,7]. The carbon-tin precursors were pyrolyzed, affording formation of tin-based nanograins encapsulated in conductive carbon buffer matrix. Optimal conditions of the thermal treatment were determined by thermal analysis methods (EGA-TGA). The resulting materials with different carbon loading (20-60 wt.%) were investigated by X-ray diffraction (XRD) and by transmission electron microscopy (TEM) as well. Comprehensive electrochemical characterization of obtained nanocomposites including the electrical conductivity (EC), cyclic voltammetry (CV) and impedance spectroscopy (IS) was carried out. Discharge - charge tests were performed in R2032-type coin cells within 0.01–1.5 V potential range.
TEM images indicate that the type of carbon precursor has strong impact on morphology of obtained carbon buffer matrix. The study also showed that columbic efficiency and capacity retention in discharge-charge tests strongly depend on carbon loading and sort of a carbon precursor.
The authors acknowledge a financial support from the National Science Center of Poland under research grant No. 2012/07/N/ST8/03725 and from the European Institute of Innovation and Technology under the KIC InnoEnergy NewMat project.
 J. W. Zheng, S. M. L. Nai, M. F. Ng, P. Wu, J. Wei, M. Gupta, J. Phys. Chem. 113 (2009) 14015-14019.
 L. Zhao, S. Hu, W. Li, L. Li, X. Hou, Rare Metals 27 (2008) 507-512.
 D. Deng, J.Y. Lee, Angew. Chem. Int. Edit. 48 (2009) 1660-1663.
 H. Kim, M. G. Kim, T.J. Shin, H. J. Shin, J. Cho, Electrochem. Commun. 10 (2008) 1669-1672.
 A. Kamali, D.J. Fray, Rev. Adv. Mater. Sci. 27 (2011) 14–24.
 M. Molenda, A. Chojnacka, M. Bakierska, R. Dziembaj, Mater. Technol. 29 (2014) A88-A92.
 A. Chojnacka, M. Molenda, M. Bakierska, R. Dziembaj, Procedia Eng. 98 (2014) 2-7.