## 4 Electrochemical Analysis
### Electrochemical Performance  
In order to evaluate and compare the electrochemical performance of the prepared composite fibers, cycling performance tests were carried out on coin cells for \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\)/C, TiO\({}_{2}\)/C, and \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\)/TiO\({}_{2}\)/C fibers at a current density of 100 mA g\({}^{-1}\) over 100 cycles. Figure 10 shows the charge (lithium extraction)/discharge (lithium insertion) curves of the composite fiber anodes. The charge/discharge curves were obtained at a constant current density of 100 mA g\({}^{-1}\) over a potential window of 0.05\(-\)3 V. By comparing the performance between \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\)/C and TiO\({}_{2}\)/C, it can be seen that \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\)/C shows a much higher initial capacity of 1735 mAh g\({}^{-1}\) than TiO\({}_{2}\)/C (318 mAh g\({}^{-1}\)). However, characteristic of \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\), this anode suffers a tremendous capacity degradation as the capacity quickly drops to 422 mAh g\({}^{-1}\) at the 2 nd cycle and finally to 121 mAh g\({}^{-1}\) after the 100 th cycle. The large capacity fade at the first cycle is attributed to the irreversible reaction characteristic of metal oxides and the formation of the SEI layer, which can be seen in all three composite fiber anodes. In this irreversible process, lithium reacts with oxygen to form lithium oxide, losing useful lithium ions to this by-product and hence leading to severe capacity loss. The later capacity fade is caused by the large volume expansion of the \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\)/C composite-fiber anode upon cycling. The TiO\({}_{2}\)/C composite-fiber anode also shows some capacity fading; however, it is not as pronounced as for the \(\alpha\)- Fe\({}_{2}\)O\({}_{3}\)/C composite-fiber anode. This can be attributed to a much more stable structure and minimal volume expansion for the TiO\({}_{2}\). The capacity of 61 mAh g\({}^{-1}\) for the TiO\({}_{2}\)/C anode after the 100 th cycles is still lower than that for \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\)/C. Figure 10: \(Cont.\)  
The cycling performance of the TiO2/C, \(\alpha\)-Fe2O3/C, and \(\alpha\)-Fe2O3/TiO2/C composite fiber anodes is shown in Figure 11A,B. The \(\alpha\)-Fe2O3/TiO2 composite fiber anode shows a better electrochemical performance than the pristine TiO2/C anode because the TiO2 provides structural stability to the composite anode, while maintaining the higher capacity resulting from the addition of the \(\alpha\)-Fe2O3 to the TiO2/C fiber precursor. This can be observed by the cycling performance of the ternary \(\alpha\)-Fe2O3/TiO2/C composite fibers which showed a high initial capacity of 1832 mAh g\({}^{-1}\) at the 1 st cycle and a capacity of 340 mAh g\({}^{-1}\) after 100 cycles. The addition of the TiO2 to the \(\alpha\)-Fe2O3 fiber precursor helped alleviate the large volume expansion, therefore reducing the capacity fading after subsequent cycles. This proves that combining both metal oxides provide an electrode with improved electrochemical performance and superior cycling stability. While the irreversible reaction at the first cycle provides a low initial coulombic efficiency for all three of the composite fiber anodes, after subsequent cycles, the composite fiber electrodes can maintain a high efficiency of about 97% (Figure 11A). Results reported in the literature showed in some cases that the Fe2O3/C electrode delivered lower capacity after 100 cycles than that for the TiO2 electrode. This poor performance was caused by the high-volume change of the Fe2O3 electrode [25]. Several studies showed that the \(\alpha\)-Fe2O3/TiO2/C delivered excellent electrochemical performance compared to the \(\alpha\)-Fe2O3 and TiO2 electrodes, which was attributed to the synergetic effect between \(\alpha\)-Fe2O3 and TiO2 which can improve the diffusion kinetics and structural stability of the electrode [24; 25; 54; 55]. Figure 11: Cycling performance of the composite fiber anodes at a current density of 100 mA g\({}^{-1}\).