Porous TiO2 urchins for high performance Li-ion battery electrode: facile synthesis, characterization and structural evolution

• Published in: Electrochimica acta 2016-08, Vol.210, p.206-214
• Main Authors: Cai, Yi, Wang, Hong-En, Huang, Shao-Zhuan, Yuen, Muk Fung, Cai, Heng-Hui, Wang, Chao, Yu, Yong, Li, Yu, Zhang, Wen-Jun, Su, Bao-Lian
• Format: Article
• Language: English
• Subjects: anode materials; electrochemistry; Li ion battery; porous structure; TiO2
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2016.05.140

[Display omitted] •A simple synthesis procedure is developed to synthesize porous TiO2 urchins.•The unique hierarchical porous TiO2 exhibits excellent electrochemical performance.•The gradual formation of Li1TiO2 dots leads to capacity degradation during cycling. Porous TiO2 urchins have been synthesized by a hydrothermal route using TiO2/oleylamine as precursors with subsequent ion-exchange and calcination. The resultant material consists of porous spherical cores and nanochains-constructed shells with straight channels. Electrochemical measurements indicate the TiO2 urchins deliver superior lithium storage capability in terms of high capacity (206.2mAhg−1 at 0.5C), superior rate performance (94.4mAhg−1 at 20C) and stable cycling stability (94.3% capacity retention over 1000 cycles at 10C versus the third cycle). Such performance enhancement is mainly due to the increased electrode/electrolyte contact interface, reduced Li+ diffusion pathways and improved mass transfer of electrolyte in the unique 3D interconnected hierarchical network. In addition, ex-situ XRD, SEM and TEM analyses further reveal high structure integrity of the porous TiO2 urchins during the electrochemical lithiation, leading to enhanced lithium storage stability. Moreover, we detected that some anatase nanocrystals evolved into electrochemically inactive Li1TiO2 dots (∼10nm in size) during long-term electrochemical cycling. Our findings provide more insights for better understanding of the structure evolution and capacity decay mechanism in porous TiO2 nanostructures.