Page 263 - Carbon Nanotube Fibres and Yarns

CNT yarn-based supercapacitors 253

Incorporating active materials to CNTs is an effective way to improve
the electrochemical properties of CNT-based SCs. CNT yarn is often pre-
pared from flexible and conductive CNT webs drawn from CNT arrays and
fillied with nanosized active materials before twist insertion to provide high
active material mass loading to improve ion and electron transportation. For
example, MnO 2 [68], PEDOT [69], PANI [70], RGO [71], and TiO 2 [72]
have been hybridized with CNT films that are further scrolled into compos-
ite CNT yarns. Liu et al. built asymmetric SCs with planar configurations,
the electrodes were loaded with vertically aligned CNTs and MnO 2 [73].
Bendable/weavable SC based on CNT yarn electrodes and PVA/H 3 PO 4
electrolyte have also been fabricated [74, 75]. Their quasi-rectangular CV
curves indicate ideal EDLC capacitive performance.

10.3 Architectures of threadlike supercapacitors

The fundamental components of the threadlike SC are the same as a tra-
ditional capacitor, which consists of two separated electrodes electrically
connected via electrolyte. In contrast to conventional planar SCs, threadlike
SCs are linear devices, therefore usually smaller in size and lighter in weight.
Threadlike SCs take one of four types of configurations, parallel ply, twisted
ply, coaxial, and serial arrangements. In general, a parallel ply threadlike SC
is composed of two separated linear electrodes connected via gel-electrolyte
which also serves as a separator (Fig. 10.3A). Twisted ply threadlike SCs
are constructed by twisting two linear electrodes together with a separator

Fig. 10.3 Schematic diagrams of different threadlike SC architectures: (A) parallel-ply,
(B) twisted ply, (C) coaxial, and (D) serial type. ((A, B) Reproduced with permission from Z.
Cai, L. Li, J. Ren, L. Qiu, H. Lin, H. Peng, J. Mater. Chem. A 1 (2013) 258–261. (C, D) Reproduced
with permission from X. Chen, H. Lin, J. Deng, Y. Zhang, X. Sun, P. Chen, X. Fang, Z. Zhang, G.
Guan, H. Peng, Adv. Mater. 26 (2014) 8126–8132.)