# The Effect of TiO2 on the Electrochemical Performance of Sb2O3 Anodes for Li-Ion Batteries
## 3 Results and Discussion
### Electrochemical Performance
More work is needed to understand the complexity of the Sb redox reactions discussed in this work. Figure 8: Cyclic voltammetry of (**A**) TiO\({}_{2}\), (**B**) Sb\({}_{2}\)O\({}_{3}\) and (**C**) TiO\({}_{2}\)/Sb\({}_{2}\)O\({}_{3}\) nanocomposite with a 3:1 ratio. The electrochemical reactions of the Sb\({}_{2}\)O\({}_{3}\) anode are described in Equations (1) and (2). \[\text{Sb}_{2}\text{O}_{3}+6\text{Li}^{+}+6\text{e}^{-}\to 2\text{Sb}+3\text{ Li}_{2}\text{O} \tag{1}\]  
\[\text{Sb}+\text{X}\text{Li}^{+}+\text{Xe}^{-}\to\text{Li}_{x}\text{Sb},\,\text{x }\leq 3 \tag{2}\]  
At the first anodic scan (Figure 8C), the oxidation peak at 1.16 V is credited towards the dealloying of Li\({}_{x}\)Sb to Sb [69], whereas the other peak at 2.03 V was attributed to TiO\({}_{2}\), which is in agreement with results reported by [PERSON] et al. [70] of repeatedly having a peak along the range of 2-2.5 V. Lastly, the peak at 2.46 V was attributed to the pyrolysis of the PAN binder during the heat treatment of the TiO\({}_{2}\)/Sb\({}_{2}\)O\({}_{3}\) slurry [71]. The results presented in Figure 8 indicate that the TiO\({}_{2}\)/Sb\({}_{2}\)O\({}_{3}\) composite anode demonstrated good electrochemical stability and reversibility during charge/discharge cycles, which is indicated by the constant overlapping of CV scans. Figures S1 and S2 show the CV scans at the first five cycles of the TiO\({}_{2}\)/Sb\({}_{2}\)O\({}_{3}\) electrodes with 1:1 and 1:4 ratios of TiO\({}_{2}\) to Sb\({}_{2}\)O\({}_{3}\), as shown in the supplementary information (Figures S1 and S2). Figure 9 shows the charge/discharge curves of the Sb\({}_{2}\)O\({}_{3}\), TiO\({}_{2}\) and TiO\({}_{2}\)/Sb\({}_{2}\)O\({}_{3}\) electrodes after 100 cycles at a current density of 100 mA g\({}^{-1}\) and with potentials ranging between 0.01 and 3.0 V (vs. Li\({}^{+}\)/Li). During the first discharge cycle (Figure 9a), a small plateau was present at around 1.70 V--which was related to the transition of Sb\({}_{2}\)O\({}_{3}\) to metallic Sb and Li\({}_{2}\)O--and a visible plateau at 1.25 V was observed that was ascribed to the formation of the SEI layer. At the first charge cycle, three minimal voltage plateaus were observed at 1.16 V, 2.0 V and 2.46 V, which corresponded to the dealloying of Li\({}_{x}\)Sb and the forming of Sb\({}_{2}\)O\({}_{3}\) and its interaction with TiO\({}_{2}\) and PAN. The initial discharge and charge capacities were 1002 mAh g\({}^{-1}\) and 632 mAh g\({}^{-1}\), experiencing a capacity loss of 35% from the 1 st discharge to the 2 nd cycle. In subsequent cycles, the capacity was stable and experienced a 2.9% loss from the 50 th to the 100 th cycle, while the anode remarkably exhibited a specific capacity of 544 mAh g\({}^{-1}\) after 100 cycles. Based on the CV scans and charge discharge profile for the TiO\({}_{2}\)/Sb\({}_{2}\)O\({}_{3}\) composite electrode, the TiO\({}_{2}\) phase tremendously assisted with the stability and the retained sufficient capacity of the Sb anode. Figure 10 shows the cycling performance and coulombic efficiency of Sb\({}_{2}\)O\({}_{3}\), TiO\({}_{2}\) and (3:1) TiO\({}_{2}\)/Sb\({}_{2}\)O\({}_{3}\) nanocomposite electrodes after 100 cycles at a current of 100 mA g\({}^{-1}\). The (3:1) TiO\({}_{2}\)/Sb\({}_{2}\)O\({}_{3}\) nanocomposite electrode displayed an initial charge capacity of 632 mAh g\({}^{-1}\), corresponding to a coulombic efficiency of 63.1%, which is higher in comparison to the pristine Sb\({}_{2}\)O\({}_{3}\) material and to commercial graphite. It is observed in Figure 10 that TiO\({}_{2}\) had a specific capacity of 175 mAh g\({}^{-1}\) at the first charge cycle and a low coulombic efficiency of 47.2%. The TiO\({}_{2}\) electrode had a steady specific capacity yet maintained a low charge capacity. The Sb\({}_{2}\)O\({}_{3}\) electrode exhibited a high charge specific capacity of 829 mAh g\({}^{-1}\) in the first few cycles, corresponding to a coulombic efficiency of 83.2%, but it experienced a large capacity loss starting at the 15 th cycle.