The cyclic voltammogram of the NFLF electrode recorded at a scan rate of 0.05 mV/s down to a vertex potential of 0.1 V vs. Li/Li + (obtained with a three-electrode setup) is shown in Fig. . Three reduction peaks can be observed, whereby the first peak at 0.98 V vs. Li/Li + can be assigned to the SEI formation, the second and third prominent peaks at 0.8 V and 0.39 V vs. Li/Li + are associated with lithium insertion of NFLF structure. However, these reactions may partially change the morphology (i.e., amorphization) of NFLF. The overlap of the 2nd and 3rd cycles reveals the good reversibility of Li storage after the 1st cycle, suggesting that a stable SEI film is formed during the initial cycle. In Fig. , even at high scan rates, the peaks related to lithium insertion/deinsertion maintain their original shape and become broader compared to peaks at low scan rates. The cathodic peaks become steeper due to diffusion-related polarization, and the anodic peaks shift to higher potentials with increasing scan rates. The storage mechanism of lithium for NFLF is firstly investigated by the Kinetic calculation. The CV data are collected at different scan rates (Fig. ), from which the ratio of the capacitive contribution could be obtained.