Na2Ti6O13 Coated with Carbon Produced by Citric Acid as an Anode Material in Sodium Ion Batteries

In this article, carbon coated sodium titanate (Na2Ti6O13) is prepared with citric acid as the carbon source, in which the graphitized carbon layer is produced after pyrolysis through a post heat-treatment process. Graphitized carbon layer can meliorate electrical conductivity of the sodium titanate, improve the capacity of anode. The electrochemical characterizations have demonstrated that carbon coated sodium titanate possesses enhanced sodium storage capability compared with the carbon free counterpart. With the increase of the number of the cycles, the capacity of the electrode is 150 mAh g−1 after 100 cycles at a current density of 50 mA g−1. At the current density of 800 mA g−1 the capacity is 106 mAh g−1 and keeps stable after 1000 cycles. We see this improvement as a result of two reasons, the graphitization of carbon, and the chemical reaction between the synthesized sodium titanate and the oxides of carbon produced by citric acid. The material is synthesized by a simple method but the capacity of which can is impressive. Thus, the synthesized sodium titanate may be a promising anode for sodium ion battery (SIB).