# CNT-Coated Quartz Woven Fabric Electrodes for Robust Lithium-ion Structural Batteries
## 3 Results and Discussion
### Material Synthesis
In terms of CNTs, the D band, located at 1350 cm\({}^{-1}\), is related to the size of the in-plane sp\({}^{2}\) domains, while the G band, located at 1600 cm\({}^{-1}\), arises from the first-order scattering of the E\({}_{2g}\) phonon of the sp\({}^{2}\) C. The D/G band of the C-QWF electrode appeared after the growth of CNTs, indicating the formation of both the new graphitic domain and defect-induced disordered sp\({}^{2}\) carbon atoms. The increase of the D/G band ratio in the C-QWF electrode provides direct evidence for the growth of CNTs on the surface of silica fabric. Table 2 shows the compositional ratio of deposited metal catalysts contributing the growth of carbon layer and CNTs in C-QWF electrode. This was confirmed by ICP-MS and EA, respectively. The elemental ratio of metal catalysts confirm that the primary deposition effectively occurred on the silica surface through the sputtering process. The increase in weight ratio from P-QWF of 0.161% to C-QWF of 0.238% also shows that the metal catalysts effectively assist the growth of CNTs. The optical image and the morphology of the P-QWF electrode are shown in Figure 2a,b. Figure 2c shows the surface of silica fiber exists without other impurities before the CVD process. After the growth of CNTs on P-QWF, the color of the QWF electrode is changed from white to black due to the existence of CNTs, and its surface also looks rougher than before, as shown in Figure 2d,e. As-synthesized CNTs are observed entangled with each other on the surface in Figure 2f. The microstructure and morphology of the QWF electrodes were observed using high-resolution transmission electron microscopy (HRTEM) as shown in Figure 3. Compared to the TEM images of the silica fiber in Figure 3a, the C-QWF homogenously spread throughout the silica fiber as shown in Figure 3b, similar to Figure 2f, and Fe nanoparticles as growth catalysts are more distinguishable. The crystallinity and phase of QWF electrodes were investigated by the selected area electron diffraction (SAED) patterns. Figure 3c shows the amorphous or very low crystalline phase of silica. In contrast, the SAED pattern of C-QWF electrode has various manifold spots, implying a poly-crystalline \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Samples**} & **EA (\%)** & \multicolumn{3}{c}{**ICP (mg kg\({}^{-1}\))**} \\ \cline{2-5}  & **Carbon** & **Aluminum** & **Iron** & **Silicon** \\ \hline P-QWF & 0.161 & 48.2 & 56.9 & 4.85 \({}^{*}\) 10\({}^{5}\) \\ C-QWF & 0.238 & 115 & 83.3 & 4.96 \({}^{*}\) 10\({}^{5}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The elemental composition of the QWF electrodes. Figure 1: (a) X-ray powder diffraction patterns (10–70\({}^{\circ}\)) of the quartz woven fabric (QWF) electrodes; (b) Raman spectroscopy of the QWF electrodes. environment of Fe nanoparticles. The ring pattern is computed as a function of the radial distance from the center of the diffraction pattern and described in the top right of Figure 3d. Figure 3: TEM images of the (**a**) P-QWF; (**b**) C-QWF and selected area electron diffraction (SAED) pattern of the (**c**) P-QWF and (**d**) C-QWF. Figure 2: (**a**) Optical image of the pristine QWF (P-QWF) electrode. SEM images of the P-QWF electrode; (**b**) Top view at low magnification; (**c**) Cross-sectional view; (**d**) Optical image of the copper nanotube (CNT)-coated QWF electrode (C-QWF) electrode. SEM images of the C-QWF electrode; (**e**) Top view at low magnification; (**f**) Cross-sectional view. The electrochemical performances of the QWF electrodes are presented in Figure 4. The reversible capacity of P-QWF electrode is under 50 mAh g\({}^{-1}\) because of the sluggish electrical conductivity of silica fiber. In the case of the C-QWF electrode, it had a discharge capacity of 640 mAh g\({}^{-1}\) in the first cycle, and dropped to 485 mAh g\({}^{-1}\) in the next cycle because of the formation of the solid electrolyte interphase (SEI) layer.