Mesoporous Na2Ti3O7 microspheres with rigid framework as anode materials for high-performance sodium ion batteries

Four types of mesoporous Na2Ti3O7 (NTO) microspheres have been successfully prepared utilizing different concentrations of NaOH treatment. The specific surface areas and pore size distributions of NTO can be well controlled by means of adjusting the amount of NaOH additives. In the meanwhile, the corresponding electrochemical performance has been detected and analyzed. It is concluded that the 3 M-NTO sample prepared with 3 M NaOH solution exhibits the best electrochemical performance. We consider that the less or excess amount of NaOH might not be beneficial to building the most optimal model for efficient Na+ ion storage. The addition of NaOH less than 2 M leads to the relatively low surface areas and pore volume, bringing about limited contact areas between active materials and Na+ ions as well as unsatisfied specific capacity. On the other hand, the excess augment of NaOH is reversely detrimental to the improvement of electrochemical performance probably owing to the fragile construction of NTO caused by the abundant mesopore distribution.