## 3 Results
### Effect of SiO\({}_{2}\) on the Morphology of Silicon Deposits  
For more detailed analysis of the effect of SiO\({}_{2}\) on the morphology of the silicon, SEM images were made. Figure 4 shows the corresponding micrographs of the deposits. It can be seen that in the KCl-K\({}_{2}\)SiF\({}_{6}\) system, silicon was deposited in the form of disordered fibers with an average diameter of 300-400 nm, while the effect of cathode overvoltage on the morphology of the deposit is not clearly observed. Such a result is probably due to the limiting stage of the preceding chemical reaction of silicon-containing ion dissociation.  
Figure 3: Photographs of the cathode deposits obtained after the electrolysis of the KCl–K\({}_{2}\)SiF\({}_{6}\)–SiO\({}_{2}\) melt at a temperature of 790 \({}^{\circ}\)C and cathode overvoltage of 0.25, 0.15, and 0.1 V vs. QRE potential.  
Figure 2: Photographs of the cathode deposits obtained after the electrolysis of the KCl–K\({}_{2}\)SiF\({}_{6}\) melt at a temperature of 790 \({}^{\circ}\)C and cathode overvoltage of 0.25, 0.15, and 0.1 V vs. QRE potential.  
When SiO\({}_{2}\) is added in the melt, silicon is predominantly deposited in the form of nano-sized tubes and needles, the length of which varies in the range of 30-60 \(\upmu\)m, and the diameter varies in the range of 200 nm to 400 nm. This effect can be interpreted as the mutual influence of several factors:  
1. a change in the composition of silicon-containing electroactive particles, namely the inclusion of oxygen atoms in their composition, leading to a decrease in binding energy of silicon atoms [51] and facilitation of the charge transfer stage;
2. a decrease in electrical conductivity (increase in resistance) of the near-cathode layer melt, which will redistribute the current lines among the cathode surface. Namely, silicon electrodeposition will occur at the tips of the deposit, rather than on the lateral surfaces;  
Figure 4: Micrographs of the cathode deposits obtained during the electrolysis of KCl–K\({}_{2}\)SiF\({}_{6}\) and KCl–K\({}_{2}\)SiF\({}_{6}\)–SiO\({}_{2}\) melts at a temperature of 790 \({}^{\circ}\)C and cathode overvoltage of 0.25, 0.15, and 0.1 V vs. QRE.  
a change in the composition of silicon-containing electroactive ions, as a result the ions activity and the rate constant of the possible preceding chemical reaction in the melt change.  
Taking into account the weak effect of the cathode overvoltage on the morphology of silicon deposits, the effect of SiO\({}_{2}\) addition can be associated with the last two factors. It can be noted that the average size of silicon particles decreases with the addition of SiO\({}_{2}\) to the melt. A similar effect was observed in other works [31; 41].  
According to EDX analysis, the average oxygen content in the fibers obtained during the electrolysis of the KCl-K\({}_{2}\)SiF\({}_{6}\) melt was 2.1-4.3 wt.%, and the average oxygen content in nano-sized tubes and needles obtained during the electrolysis of this melt with the addition of SiO\({}_{2}\) was 2.7-5.1 wt.%. The appearance of oxygen in the deposits can be caused both by the use of a quartz retort as a reactor container and after-electrolysis silicon treatment. It is important to note that the addition of SiO\({}_{2}\) does not significantly increase oxygen content in silicon deposits, which is important from the point of the electrochemical characteristics as the anode of LIB.