Carbon nanotube@layered nickel silicate coaxial nanocables as excellent anode materials for lithium and sodium storageElectronic supplementary information (ESI) available: SEM image of carbon nanotubes; SEM images of CNT@NiSiOx and NiSNTs synthesized at different times; SEM image and XRD patterns of CNT@NiSiOx after calcination at different temperatures. See DOI: 10.1039/c5ta03408f

• Main Authors: Gui, Chen-Xi, Hao, Shu-Meng, Liu, Yuan, Qu, Jin, Yang, Cheng, Yu, Yunhua, Wang, Qian-Qian, Yu, Zhong-Zhen
• Format: Journal Article
• Language: English
• Published: 04.08.2015
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c5ta03408f

Layered nickel silicate provides massive interlayer space similar to graphite for the insertion and extraction of lithium ions and sodium ions; however, the poor electrical conductivity limits its electrochemical applications in energy storage devices. Herein, carbon nanotube@layered nickel silicate (CNT@NiSiO x ) coaxial nanocables with flexible nickel silicate nanosheets grown on conductive carbon nanotubes (CNTs) are synthesized by a mild hydrothermal method. CNTs serve as conductive cables to improve the electron transfer performance of nickel silicate nanosheets, resulting in reduced contact and charge-transfer resistances. In addition to a high specific surface area, short ion diffusion distance and good electrical conductivity, one-dimensional coaxial nanocables have a stable structure to sustain volume change and avoid structure destruction during the charge-discharge process. As an anode material for lithium storage, the first cycle charge capacity of the CNT@NiSiO x nanocables reaches 770 mA h g −1 with the first cycle coulombic efficiency as high as 71.5%. Even after 50 cycles, the charge capacity still reaches 489 mA h g −1 at a current density of 50 mA g −1 , which is nearly 87% and 360% higher than those of the NiSiO x /CNT mixture and nickel silicate nanotube, respectively. As anode materials for sodium storage, the coaxial nanocables exhibit a high initial charge capacity of 576 mA h g −1 , which even retains 213 mA h g −1 at 20 mA g −1 after 16 cycles. Synthesized carbon nanotube@layered nickel silicate coaxial nanocables exhibit improved electrochemical performance and good structural stability as anode materials for lithium/sodium ion batteries.