## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Anodes**} & **Mass Loading** & **First Reversible** & \multicolumn{2}{c}{**Cycle Performance**} & **Rate Performance** & \multirow{2}{*}{**Reference**} \\  & **(mg cm\({}^{-2}\))** & **Capacity** & **(mAh g\({}^{-1}\))** & **(mAh g\({}^{-1}\))** & **(mAh g\({}^{-1}\))** \\ \hline V\({}_{2}\)O\({}_{3}\)/MCCNFs & 1.5–2.5 & 790.6 (0.1 A g\({}^{-1}\)) & 487.7 (5 A g\({}^{-1}\), 5000 cycles) & 456.8 (5 A g\({}^{-1}\)) & [7] \\ SméC@CNF & 2.0 & 891.2 (0.1 A g\({}^{-1}\)) & 610.8 (0.2 A g\({}^{-1}\), 180 cycles) & 305.1 (2 A g\({}^{-1}\)) & [9] \\ SnS/CNFs & / & 898 (0.05 A g\({}^{-1}\)) & 548 (0.5 A g\({}^{-1}\), 500 cycles) & 206 (4 A g\({}^{-1}\)) & [14] \\ \(\gamma\)-Fe\({}_{2}\)O\({}_{3}\)/C films & 1.0 & 923.97 (0.2 A g\({}^{-1}\)) & 1088 (0.2 A g\({}^{-1}\), 300 cycles) & 380 (5 A g\({}^{-1}\)) & [15] \\ am-Fe\({}_{2}\)O\({}_{3}\)/rGO/CNFs & 1.5–2.0 & 825 (0.1 A g\({}^{-1}\)) & 739 (1 A g\({}^{-1}\), 400 cycles) & 570 (2 A g\({}^{-1}\)) & [16] \\ In\({}_{2}\)O\({}_{9}\)@CF & 1.4 & 510 (0.1 A g\({}^{-1}\)) & 435 (0.1 A g\({}^{-1}\), 500 cycles) & 190 (1.5 A g\({}^{-1}\)) & [17] \\ MnSe@C-700 & 1.6 & 614.6 (0.1 A g\({}^{-1}\)) & 684 (0.1 A g\({}^{-1}\), 100 cycles) & & [18] \\ NCNFs & 7.64 & 752.3 (0.05 A g\({}^{-1}\)) & 419.0 (1 A g\({}^{-1}\), 160 cycles) & 148.8 (2 A g\({}^{-1}\)) & [19] \\ CNF@SnO\({}_{2}\) & 1.77–3.54 & 793 (0.5 A g\({}^{-1}\)) & 485 (0.1 A g\({}^{-1}\), 850 cycles) & 359 (4 A g\({}^{-1}\)) & [20] \\ G/Si@CFs & 0.65–1 & 1036 (0.1 A g\({}^{-1}\)) & 896.8 (0.1 A g\({}^{-1}\), 200 cycles) & 543 (1 A g\({}^{-1}\)) & [21] \\ C/CuO/rGO & 1.30–195 & 550 (0.1 A g\({}^{-1}\)) & 400 (0.1 A g\({}^{-1}\)) & 600 cycles) & 300 (2 A g\({}^{-1}\)) & [22] \\ FeCo@CNFs-600 & 1.77–2.65 & 736.3 (0.1 A g\({}^{-1}\)) & 566.5 (0.1 A g\({}^{-1}\), 100 cycles) & 130 (2 A g\({}^{-1}\)) & [23] \\ SnO\({}_{2}\)/TiO\({}_{2}\)@CNFs & / & 1061.2 (0.1 A g\({}^{-1}\)) & 729.6 (0.1 A g\({}^{-1}\), 150 cycles) & 206.2 (3 A g\({}^{-1}\)) & [24] \\ MoO\({}_{2}\)/C & 85.7 & 752.5 (0.2 A g\({}^{-1}\)) & 450 (2 A g\({}^{-1}\), 500 cycles) & 432 (2 A g\({}^{-1}\)) & [25] \\ FCNF-3/4 & 1.0 & 775 (0.2 A g\({}^{-1}\)) & 630 (0.2 A g\({}^{-1}\), 100 cycles) & 250 (5 A g\({}^{-1}\)) & [26] \\ Fe\({}_{2}\)O\({}_{4}\)/NCNFs & 1.33 & 686 (0.1 A g\({}^{-1}\)) & 522 (0.1 A g\({}^{-1}\), 200 cycles) & 407 (5 A g\({}^{-1}\)) & [27] \\ Fe\({}_{2}\)O\({}_{3}\)/SnO\({}_{3}\)/CNF & / & 797 (0.1 A g\({}^{-1}\)) & 756 (0.1 A g\({}^{-1}\), 55 cycles) & 540 (1 A g\({}^{-1}\)) & [28] \\ V\({}_{2}\)O\({}_{3}\)/CNF & / & 415.3 (0.2 A g\({}^{-1}\)) & 420 (0.2 A g\({}^{-1}\), 100 cycles) & 80 (10 A g\({}^{-1}\)) & [29] \\ ZnSe@CNFs-2.5 & 0.8–1.2 & 737.5 (0.1 A g\({}^{-1}\)) & 426.1 (5 A g\({}^{-1}\), 3000 cycles) & 547.6 (5 A g\({}^{-1}\)) & [30] \\ SiOC/C fibers-NH & 0.8–1.5 & 518 (0.2 A g\({}^{-1}\)) & 595 (0.2 A g\({}^{-1}\), 200 cycles) & 195 (4 A g\({}^{-1}\)) & [31] \\
10-SnO\({}_{2}\)@CNFs/CNT & 1.5–2.5 & 500.9 (0.1 A g\({}^{-1}\)) & 460.3 (0.1 A g\({}^{-1}\), 200 cycles) & 222 (32 A g\({}^{-1}\)) & [32] \\ \(\gamma\)-Fe\({}_{2}\)O\({}_{9}\)@CNFs & 2.0 & 1065 (0.5 A g\({}^{-1}\)) & 430 (6 A g\({}^{-1}\), 100 cycles) & 222 (60 A g\({}^{-1}\)) & [33] \\ CNFs-2N & 1.2 & 1108.9 (0.05 A g\({}^{-1}\)) & 954.3 (0.05 A g\({}^{-1}\), 100 cycles) & 549.7 (1 A g\({}^{-1}\)) & This work \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Electrochemical performances of flexible carbon fiber anodes for lithium-ion batteries reported elsewhere and in this work. increase in the charge transfer impedance after N-doping may be due to the formation of a larger SEI film after forming pores, which makes CNFs-2N possess a larger specific surface area. However, the ideal pore size distribution can shorten the ion diffusion path and provide more active sites. Moreover, the porous structure can accommodate the volume strain and inhibit the volume expansion in the process of Li\({}^{+}\) insertion/de-insertion to achieve long-term cycle stability.