# Synthesis of C/SiC Mixtures for Composite Anodes of Lithium-Ion Power Sources
## 2 Materials and Methods  
Scheme of the synthesis: The synthesis of SiC powder was carried out in a graphite crucible, which was placed in a protective alumina crucible. Mixture of SiO\({}_{2}\) and graphite powder with molar ratio of 1-3 was prepared by hand mixing in agate mortar and placed in a crucible. Graphite crucible was covered with graphite cap and buried under extra graphite layer. Synthesis was conducted at a temperature of 1600 \({}^{\circ}\)C for 5 h under CO atmosphere. In such reactor and conditions, the atmosphere maintained stable due to the oxidation of graphite powder [40; 41]. The scheme for the synthesis of SiC-based mixtures with different compositions is shown in Figure 1. It was shown experimentally that mixtures with 40-95 wt% SiC and unreacted graphite are formed during synthesis depending on the given SiO\({}_{2}\):C ratio, temperature and synthesis duration; the products may also contain traces of silicon and its nonstoichiometric oxides, which are removed by additional treatment in the HF solution. Therefore, the primary synthesis products are the C/SiC mixtures. The ratio of components in such mixtures can be controlled in order to obtain required mixture.  
In this work we synthesized a C/SiC mixture and pure SiC that were studied in the anode half-cell of LIBs. Along with these materials, a composite anode based on the resulting C/SiC mixture with the addition of electrtodeposited silicon fibers from the KCl-K\({}_{2}\)SiF\({}_{6}\) melt was also tested [42].  
Analysis of the morphology and composition: The chemical and phase composition of the reagents and products was determined by inductively coupled plasma atomic emission  
Figure 1: Process flow diagram for obtaining C/SiC mixtures for the manufacture of LIBs anodes.  
spectroscopy (AES-ICP) using iCAP 6300 Duo Spectrometer (Thermo Scientific, Waltham, MA, USA), X-ray phase analysis (XRD) using Rigaku D/MAX-2200 VL/PC diffractometer (Rigaku, Tokyo, Japan) and Raman spectroscopy using U1000 Raman spectrometer (Renishaw, New Mills, UK). The morphology and elemental composition of the obtained samples were studied using a Tescan Vega 4 (Tescan, Brno-Kohoutovice, Czech Republic) scanning electron microscope with Xplore 30 EDS detector (Oxford, UK).  
Electrochemical performance: Electrochemical performance of SiC, C/SiC and Si/C/SiC anodes were investigated in a 3-electrode half-cell. The obtained compositions were mixed with 10 wt% polyvinylidene fluoride dissolved in N-methyl-2-pyrollidone without any other additives. LIBs anode half-cell fabrication was performed in an argon-filled glove box (O\({}_{2}\), H\({}_{2}\)O \(<\) 0.1 ppm). Stainless steel mesh with the applied composite anode material was used as the working electrode and two separate lithium strips as the counter and reference electrodes. All electrodes were divided by 2 layers of polypropylene separator and tightly placed in the cell. The cell was filled with 1 mL of electrolyte--1 M LiPF\({}_{6}\) in a mixture of ethylene carbonate/dimethyl carbonate/diethyl carbonate (1:1:1 by volume). Electrochemical measurements and cycling experiments were performed using a Zive-SP2 potentiostat (WonATech, Seoul, Republic of Korea).