High lithium ion battery performance enhancement by controlled carbon coating of TiO2 hierarchically porous hollow spheres

Jun Jin, Xiao Ning Ren, Yi Lu, Xian Feng Zheng, Hong En Wang, Li Hua Chen, Xiao Yu Yang, Yu Li, Bao Lian Su

Research output: Contribution to journalArticlepeer-review

Abstract

Hierarchically porous TiO2/carbon hollow spheres (TiO2/C-HS) have been designed and prepared through a facile one-pot template-free hydrothermal route using sucrose as a carbon source, TiO2 solid spheres as a TiO2 source and NH4F as a structure-directing reagent. The nanocrystal constructed hierarchically porous hollow spherical structure offers enough space for electrolyte penetration and storage and a short path length for Li+ diffusion and e- transport. The carbon layer on TiO2 surface improves its conductivity as well as the structure stability. As a result, such a special hollow structure with carbon layers exhibits enhanced lithium storage properties comparing with the solid spheres. The TiO2/C-HS anode exhibits discharge capacities of 286, 235, 197, 164 and 127 mA h g-1 at various rates of 0.2, 0.5, 1, 2 and 5C (1C = 168 mA g-1), respectively. A capacity of 175 mA h g-1 still remains after 200 cycles at 1C, demonstrating a very high lithium insertion coefficient of 0.52, a little higher than the theoretical value of 0.5. SEM, TEM, HRTEM and electrochemical impedance spectra (EIS) techniques have been utilized to understand the Li+ insertion process and structural stability. Our results reveal that the high electrochemical performance of the TiO2/C-HS anode can be attributed to the synergy of the hierarchically porous hollow structure, carbon layer and newly formed numerous ∼5 nm Li2Ti2O4 on the surface of the TiO2 nanocrystals.

Original languageEnglish
Pages (from-to)70485-70492
Number of pages8
JournalRSC Advances
Volume6
Issue number74
DOIs
Publication statusPublished - 1 Jan 2016

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