Despite the low price of commercial TiO2 (c-TiO2), the poor electrochemical performance restricts its practical application in Li-ion batteries, so clarifying the reasons and taking appropriate measures to improve the performance are of great significance. Herein, c-TiO2 was coated with carbon at 600 and 750 degrees C using glucose as the carbon source. The product obtained at 750 degrees C exhibits markedly enhanced reversible capacities and outstanding rate performance compared to that obtained at 600 degrees C. In terms of the comparative experiments and detailed characterizations by several techniques, the SO42- remained in the c-TiO2 is the dominant impurity affecting the electrochemical performance mostly. The thorough decomposition of SO42- at 750 degrees C and the formation of carbon coating give rise to the enhanced electronic and ionic conductivities of the c-TiO2, and thus are responsible for the significant improvement in the electrochemical performance. The easy fabrication and the low cost of the raw materials enable the carbon-coated c-TiO2 to industrially apply in the LIBs. (C) 2017 Elsevier Ltd. All rights reserved.