## 3 Results and Discussion
The EDX elemental compositions of the selected regions of Figure 5a) are presented in Figure S6 in the Supplementary Materials. The differences between the ternary composites of various tin content are presented in Figure S7 in the Supplementary Materials. It is shown that the samples with a lower content of the tin precursor show much smaller tin accumulation and greater distances between each tin nanoparticle than samples where 60 wt.% of tin precursor was added. These results confirm that carbothermal reduction occurs mainly in the ceramic phase. Figure 3: SEM image of (**a**) SiOC and (**b**) SiOC-C\({}_{0.2}\)/Sn-40% composite; (**c**–**f**) X-ray elemental maps of silicon, carbon, oxygen, and tin of the SiOC-C\({}_{0.2}\)/Sn-40% composite. The influence of the carbothermal reduction on the ceramic microstructure was tracked through the \({}^{29}\)Si solid-state NMR measurements. The pure ceramic sample (Figure 6a) exhibited peaks corresponding to various SiO\({}_{\text{x}}\)C\({}_{\text{y}}\) mixed bonds tetrahedra, with plenty of Si-C bonds present [50]. On the other hand, all the ternary SiOC/C/Sn composites (Figure 6b-d)) revealed only one peak at around \(-114\) ppm, which corresponds to SiO\({}_{4}\) units [51, 52]. No peaks indicating Si-C bonds were detected. The presence of exclusively SiO\({}_{4}\) units indicates the depletion of carbon atoms bound to Si, which was explained by oxidation of C and Si by SnO\({}_{2}\) during its reduction to metallic Sn [14]. These results suggest that during carbothermal reduction, not only the free carbon phase but also carbon from the mixed bonds of silicon tetrahedra are preferably consumed compared with graphite. Figure 4: TEM pictures of (**a**) SiOC/Sn-40% and (**b**) SiOC:C\({}_{0.2}\)/Sn-60% composites. Figure 5: (**a**) HAADF image of a SiOC:C\({}_{0.2}\)/Sn-60% particle with separated ceramic and graphitic phases; TEM images of (**b**) ceramic phase and (**c**) graphitic phase. The electrochemical activity of the composite materials was investigated by means of cycling voltammetry and galvanostatic charge-discharge techniques. The CV curves present a general electrochemical pattern similar for all the investigated ternary composites, as presented in Figure 7a,b and Figure S8 in Supplementary Materials. The first cathodic sweep differs from the following cycles. In the first lithiation process, a long shoulder between 1.4 V and 0.66 V emerges, disappearing in subsequent cycles, which can be attributed to the creation of a solid-electrolyte interface (SEI) on all of the three components of the composites [19; 53; 54; 55]. Then, at lower potentials, a broad feature at about 0.46 V appears, which is related to the formation of different Li\({}_{x}\)Sn\({}_{3}\) alloys, mainly LiSn. In the following cycles, this peak splits into two peaks with maxima at 0.32 V and 0.61 V, which correspond to Li\({}_{y}\)Sn\({}_{2}\) and Li\({}_{2}\)Sn\({}_{3}\) phases, respectively [55; 56; 57]. In the potential range between 0.36 V and 0.005 V, multiple reactions occur, which can be attributed to the creation of high-lithium tin alloys and Li\({}^{+}\) intercalation into the graphite and ceramic phases [58; 59; 53; 60]. During the anodic sweep at low potentials, three peaks at 0.1, 0.17, and 0.24 V appear, which come from a gradual deinsertion of lithium ions from graphite [53; 59]. The following peaks in the range between 0.3 and 0.9 V correspond to a gradual dealloying of Li\({}_{x}\)Sn\({}_{y}\)[57]. A small broad peak at approximately 1.1 V, fading with the following cycles, can be attributed to partial oxidation of \(\sim\)1 nm size Sn nanoparticles [61; 62]. The cyclic voltammetry curves confirm the electrochemical activity of all components of the composites and indicate the creation of both high intercalation graphite stages (LiC\({}_{6}\)) and high-lithium tin compounds. The electrochemical activity of the ternary composites of different compositions is compared in Figure 7b.