Synthesis And Electrochemical Performance Of Na₂Ti₃O₇@CNT Anode Materials For Sodium-ion Batteries

Sodium ion batteries have been studied as early as 1970’s and 1980’s, however attention on sodium ion batteries has not been strong from researchers, because of the excellent electrochemical properties of lithium ion batteries which drew great interest. At present, there is high demand on lithium ion batteries, however, lithium resource(Li2CO3) is limited which restricts its development. Therefore, development of next generation new energy storage devices with reasonable price, high safety and excellent comprehensive performance is of particularly important. Elements sodium and lithium are in the same main group, sodium ion battery will be a next generation battery because of its low cost, abundant resource, and high safety that are superior than that of lithium ion battery. This fact provides a solid foundation for the development of sodium ion battery. The innovation of electrode materials will be the key to realize the high performance sodium ion battery.In this work, synthesis of Na2Ti3O7@CNT anode materials for sodium ion battery were carried out by a hydrothermal method, the microstructure and physical properties of the prepared materials were characterized by X-Ray Diffraction(XRD), Scanning Electron Microscope(SEM), Transmission Electron Microscope(TEM) and Thermal Gravimetry(TG) techniques. The electrochemical properties of the electrode materials were studied by battery test equipment and electrochemical workstations. The results show that the hydrothermal synthesized Na2Ti3O7@CNT material has demonstrated ribbon morphology with improved conductivity. The Na2Ti3O7@CNT exhibits a high discharge capacity of 400 m Ah g-1, and a good long cycle performance and rate performance. After 50 cycles at 0.1 C, the capacity maintains at 200 m Ah g-1, and at 30 C high charge and discharge rate, the capacity is 75 m Ah g-1. Synthesis of Na4Ti5O12 was further carried out by calcination of Na2Ti3O7 at elevated temperature(750°C), the Na4Ti5O12 also demonstrated good rate and cycle performance.