Page 386 - Polymer-based Nanocomposites for Energy and Environmental Applications

Nanofibrous composites for sodium-ion batteries 347

Fig. 12.5 (A) Schematic representation of the sodiation process and (B) rate capability of
Sb/ICNN anodes.
Adapted with permission from Hou H, Jing M, Yang Y, Zhang Y, Song W, Yang X, et al.
Antimony nanoparticles anchored on interconnected carbon nanofibers networks as advanced
anode material for sodium-ion batteries. J Power Sources 284;2015:227–35.

layer deposition can increase the capacity up to 700 mAh/g at the same current density
[46]. On the other hand, MoS 2 cover on Ni 3 S 2 /MoS 2 nanofibers on a Ni foam obtained
by hydrothermal synthesis can achieve capacity of 638 mAh/g (0.1 A/g) [49].The
capacities of the porous FeS and the WS x /WO 3 nanobush anodes are 413 mAh/g
[47] and about 500 mAh/g at current density of 1 A/g [48], respectively.
Diselenides, as another layered active material embedded into 1-D carbonaceous
structure or as binary metal nanofibers, also provide high rate capability. Diselenoxo-
molybdenum (MoSe 2 ) coaxial-cable carbon composite obtained by hydrothermal syn-
thesis exhibits capacity of 392 mAh/g at 0.1 A/g [50]. NiSe 2 porous CNFs containing
graphene oxide (GO) were produced by electrospinning and subsequent selenization
[52]. These nanofibers showed higher electrochemical performances reaching
capacity of 461 mAh/g at 0.1 A/g. In another study, hollow FeSe 2 —graphitic carbon
(GC)—GO nanospheres embedded into a hybrid nanofiber structure were produced by
electrospinning and thermal treatment under H 2 Se gas [53]. The high rate capability
and cycling stability of this diselenide composite were attributed to the fast and conti-
nuous electron pathway through the 3-D nanofibrous network and the easy Na-ion
diffusion within the hollow structure. On the other hand, Co 1/3 Fe 2/3 air-stabilized
nanofibers obtained by electrospinning and a subsequent selenization form
(Co 1/3 Fe 2/3 )Se 2 nanofibers [51]. These bimetal diselenide NFs without carbon form
highly crystallized hierarchical fiber-in-tube structure in which Se is more accessible
to the Na ions and gives higher electron conductivity. In contrast, in the carbon
(C)-containing nanofibers, Se is embedded within the pores of the carbon structure.
Despite that, both showed high capacities and the noncarbon nanofibers also showed
higher rate performances, exhibiting capacity of 497 mAh/g (359 mAh/g for the
C-containing) at current density of 5 A/g.
From the group of transition metal oxide active anode materials for NIB, the beha-
viors of the fibrous structures of titanium, copper, cobalt, and iron oxides and their
alloys have been investigated. Due to its intercalation mechanism for storing Na ions,