Structural and preliminary electrochemical characteristics of palm oil based carbon nanospheres as anode materials in lithium ion batteries

Copyright © Korean Carbon Society http://carbonlett.org Since the invention of the lithium-ion battery (LIB) in the early 1990s by SONY, graphite carbon has been used as the anode material because of its low cost, chemical stability, and stable electrochemical performance [1]. The limitations of graphite anodes, especially related to their small energy and power output per unit mass or volume, are retarding the development of certain high-tech industries such as hybrid electric vehicles and stationary energy storage [2]. Therefore, there is currently an intense search for new anode materials for LIBs, with high specific capacity and energy density [3,4]. In recent decades, the development of nano-carbon materials with well-defined characteristics, such as fullerenes, nanotubes, and graphene; has been a very active area of research [5]. Carbon nanospheres (CNSs) are another class of nanostructured carbon materials, and have shown good prospects for application as alternative LIB anodes [6]. CNSs possess some remarkable characteristics useful in LIB anode materials, such as high specific capacity and good rate capability. Those specific characteristics are attributed to a combination of several factors, including short diffusion paths for Li+ ions, good porosity, and large surface area [7]. CNSs can be synthesized by various techniques and these influence the characteristics of the resulting carbon products in terms of sphere size, size distribution, crystallinity, and microstructure. The processes by which CNSs are synthesized include chemical vapor deposition [8], hydrothermal carbonization [9], laser ablation [10], and polymerization-carbonization [11]. Carbon based materials were initially made from petroleum-derived compounds. Because of the depletion of carbon deposits and very serious concerns about global climate change and environmental pollution, the use of renewable natural resources (e.g., biomass) for production of carbon materials has been intensively explored in recent years [12]. In this work, the synthesis of CNSs on the surface of activated carbon support was carried out using a thermal-assisted catalytic pyrolysis technique and utilizing palm oil as renewable and eco-friendly carbon source. Specifically, the effect of the amount of Fe-catalyst on the structural and electrochemical characteristics of the CNSs will be reported. Commercial activated carbon (102836, Merck) has been used as a catalyst support without prior treatment. Analytical grade Fe(NO3)2 was used as catalyst. The catalyst was deposited onto the carbon support using the urea deposition method. In this method, 2 g of activated carbon was mixed with Fe(NO3)2 solution at various ratios (10%, 20%, and 30% with respect to the weight of the activated carbon). The ratio of Fe(NO3)2 to urea was set at the molar ratio of 1:3. The mixtures were shaken for 4 h at 90°C, cooled down overnight, and centrifuged at 6000 r/min for 15 min. The cake so obtained was then dried at 110°C for 24 h and then mixed with palm oil at the mass ratio of 1:3. The CNS were synthesized by pyrolyzing mixtures of activated carbon, urea, Fe(NO3)2, DOI: http://dx.doi. org/ DOI:10.5714/CL.2016. 18.080