Improve the Electrochemical Performance of Na2Ti3O7 Nanorod through Pitch Coating

Na2Ti3O7 is proposed as a potential anode for sodium ion batteries (SIBs) because of its advantages of low operating voltage, high energy density, and low cost. However, the low conductivity and the structural instability of the intercalated phase limit its practical application. Herein, Na2Ti3O7@C nanorod composites are prepared by using Na2Ti3O7 as the active substance particles and pitch as the carbon precursor. Pitch is selected due to the characteristics of low crystallinity, easy graphitization, and porous structure after carbonization. The results of electrochemical performance tests show that the Na2Ti3O7@C composite electrode has a good rate performance and stable cycle stability. In addition, the electrode thickness expansion rate of the Na2Ti3O7@C composite (22.28%) is lower than that of pure Na2Ti3O7 (117.51%). The improvement of electrochemical performances mainly benefit from the porous structure of the pitch carbon layer, which reduces the volume expansion of Na2Ti3O7 material from the charge–discharge process, avoids the damage of the solid electrolyte interphase (SEI) film outside the Na2Ti3O7@C composites, and thus maintains the integrity of the structure to extend the service life. This work offers some new perceptions into the mechanism of carbon coating.