Hollow and hierarchical Na2Li2Ti6O14 microspheres with high electrochemical performance as anode material for lithium-ion battery

Relying on a solvent thermal method, spherical Na2Li2Ti6O14 was synthesized. All samples prepared by this method are hollow and hierarchical structures with the size of about 2-3 m, which are assembled by many primary nanoparticles (similar to 300 nm). Particle morphology analysis shows that with the increase of temperature, the porosity increases and the hollow structure becomes more obvious. Na2Li2Ti6O14 obtained at 800 degrees C exhibits the best electrochemical performance among all samples. Charge-discharge results show that Na2Li2Ti6O14 prepared at 800 degrees C can delivers a reversible capacity of 220.1, 181.7, 161.6, 144.2, 118.1 and 97.2 mA h g(-1) at 50, 140, 280, 560, 1400, 2800 mA g(-1). However, Na2Li2Ti6O14-bulk only delivers a reversible capacity of 187, 125.3, 108.3, 88.7, 69.2 and 54.8 mA h g(-1) at the same current densities. The high electrochemical performances of the as-prepared materials can be attributed to the distinctive hollow and hierarchical spheres, which could effectively reduce the diffusion distance of Li ions, increase the contact area between electrodes and electrolyte, and buffer the volume changes during Li ion intercalation/deintercalation processes.