Supporting Information Cathodic Titania Nanotube Arrays as Anode Material for Lithium-ion Batteries Tauseef Anwar1, Wang Li1, Rizwan Ur Rehman Sagar2, Farhat Nosheen3, Rajan Singh4, Hasnain Mehdi Jafri5, Khurram Shehzad6, Liang Tongxiang1*

1State key Lab of New Ceramic and Fine Processing, Institute of Nuclear and New Energy Technology,

Tsinghua University, Beijing 100084, P.R. China.

2Nanshan District Key Lab for Biopolymer and safety Evaluation, College of Material Science & Engineering

and Department of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.

3Sulaiman Bin-Abdullah Aba Al-Khail-Centre of Interdisciplinary Research in Basic Sciences (SA-CIRBS),

International Islamic University, Islamabad, Pakistan.

4Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University,

Beijing 100084, China.

5Department of physics, University of Science and Technology Beijing, Beijing 100043, China.

6College of Information Science and Electronic Engineering and State Key Laboratory of Silicon Materials,

Zhejiang University, Hangzhou 310027, China.

*Corresponding author: [email protected] Fig. S1 Color change after cathodic reduction (a) anodic-TNAs (b) cathodic-TNAs . Fig. S2 TEM image of (a) anodic-TNAs (b) cathodic-TNAs . Fig. S3 XPS survey of (a) anodic-TNAs (b) self doped TNAs. Fig. S4 core level XPS of Ti2p3/2 after argon sputtering. Fig. S5 First discharge areal capacity of anodic-TNAs and cathodic-TNAs . Fig. S6 XRD of cathodic TNAs before and after cyclic performance. The SEM was done after gravimetric cycling to conform changes in morphology of TNAs. The

SEM shows no particular change in TNAs morphology but the wall thickness increased after gravimetric cycling which support XRD results that lithium is inserted in TNAs which have minute pulverization Fig. S7.

Fig. S7 SEM of cathodic TNAs after cyclic performance.