Cathode and Anode Materials for Na-Ion Battery - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 406

Fig. 21 SEM of carbon microspheres. b Voltage/capacity plots corresponding to the first
discharge/charge cycles of carbon aerogel microspheres in Na cells, 1 M NaClO 4 dissolved in
different solutions as electrolyte [ 57 ]
Fig. 22 a SEM images of the PANI-HNWs. b Cycle performance of the HCNW electrode at a
current density of 50 mA/g (0.2 C) [ 58 ]
EC-THF mixture electrolyte (Fig. 21 b). Cao et al. reported hollow carbon
nanowires (HCNWs) prepared by the pyrolyzation of a hollow polyaniline nano-
wire precursor (Fig. 22 a) [ 58 ]. The HCNW electrode delivered high reversible
capacity of 251 mAh g -1 and excellent cycling stability (82.2 % of capacity
retention over 400 cycles) (Fig. 22 b). Such excellent electrochemical performance
was ascribed to the HCNWs that had a uniform hollow nanowire structure and an
appropriate interlayer distance, leading to short diffusion distance for Na insertion,
stable material structure, and feasible approach for Na-ion insertion into carbon
layers. Besides, Komaba et al. reported the effect of electrolytes on Na insertion
behavior in hard carbon [ 59 ]. It was found that in EC:DEC(1:1) solution con-
taining 1 mol L -1 NaClO 4 , the hard carbon electrode exhibited a high capacity of
ca. 240 mAh g -1 with a stable capacity retention over 100 cycles. This was related