Symbiotic Coaxial Nanocables: Facile Synthesis and an Efficient and Elegant Morphological Solution to the Lithium Storage Problem

Abstract

Well-organized carbon nanotube (CNT)@TiO 2 core/porous-sheath coaxial nanocables are synthesized by controlled hydrolysis of tetrabutyl titanate in the presence of CNTs, and investigated with scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and electrochemical experiments. The CNT@TiO 2 coaxial nanocables show excellent rate capability and cycling performance compared with both pure CNT and pure TiO 2 when used as anode materials for lithium-ion batteries (LIBs). Both the specific capacity in the CNT core and that in the TiO 2 sheath are much higher than that of the TiO 2 -free CNT and that of the CNT-free TiO 2 sample, respectively. These results demonstrate that the coaxial cable morphology provides a clever solution to the ionic-electronic wiring problem in LIBs as well as the synergism of the two cable wall materials. On one hand, the CNT core provides sufficient electrons for the storage of Li in TiO 2 sheath. On the other hand, the CNT itself can also store Li whereby this storage kinetics is, in turn, improved by the presence of the nanoporous TiO 2 because the only very thin protection layer on TiO 2 (unlike free CNT) enables rapid access of Li-ions from the liquid electrolyte. This fascinating symbiotic behavior and the fact that the cable morphology leads to an efficient use of this symbiosis makes this solution match the requirements of LIBs extremely well.

Microwave autoclave synthesized multi-layer graphene/single-walled carbon nanotube composites for free-standing lithium-ion battery anodes

“…Hence, it can be concluded that graphene can be used to efficiently increase the mass density of the CNT films. This may benefit the electrochemical performance by minifying the initial irreversible capacity [28,29].…”

Silicon-based nanomaterials for lithium-ion batteries

“…Furthermore, the nanocables displayed a specific capacity of 1490 and 1140 mAh g −1 as increasing the current density to 2800 and 7000 mA g −1 , respectively. The remarkably high rate capability mainly benefits from the unique configuration of nanocables with excellent ionic-electronic conductivity [19][20][21]. The attractive structure of Cu-Si-Al 2 O 3 nanocables enabled lithium ion to diffuse readily into Si nanolayer from the outside liquid electrolyte.…”

Titania Nanosheets Hierarchically Assembled on Carbon Nanotubes as High‐Rate Anodes for Lithium‐Ion Batteries

“…Additionally, to improve the electronic conductivity of TiO 2 -based electrodes, the strategy of synthesizing composites that incorporates a conductive matrix has been widely practiced. [13][14][15][16][17] For instance, both mesoporous TiO 2 -carbon nanocomposites and coaxial nanocables that consist of carbon nanotubes (CNTs) and TiO 2 have been reported to have enhanced capacity retention at high charge-discharge rates, mainly due to the improvement in conductivity. [13,16] Therefore, it is proposed that a hybrid structure, constructed by grafting TiO 2 NSs onto conductive supports such as carbon nanotubes, would possess the advantages of both fast Li-ion insertion and enhanced electronic conductivity.…”