Facile strategy to fabricate Na2Li2Ti6O14@Li0.33La0.56TiO3 composites as promising anode materials for lithium-ion battery

A robust strategy has been developed to fabricate Na2Li2Ti6O14@Li0.33La0.56TiO3 composites as promising anode materials for lithium-ion battery. Li0.33La0.56TiO3 modification does not change the basic structure of Na2Li2Ti6O14 but enhances the lattice parameter because few trivalent lanthanum ions enter the crystal lattice of Na2Li2Ti6O14. All samples show similar morphology with a narrow size distribution ranged from 100 to 500 nm. HRTEM test demonstrates that a good conductive connection between the Na2Li2Ti6O14 and Li0.33La0.56TiO3 layer is successfully formed. The electrochemical tests show that Na2Li2Ti6O14@Li0.33La0.56TiO3 (5 wt%) sample exhibits the lowest charge-transfer resistance, highest reversibility of lithium insertion/extraction, and the largest Li-ion diffusion coefficient among all samples, and then shows the best electrochemical activity. Hence, the Na2Li2Ti6O14@Li0.33La0.56TiO3 (5 wt%) electrode reveals the largest lithiation and delithiation capacities at each current density. The Na2Li2Ti6O14@Li0.33La0.56TiO3 (5 wt%) shows excellent cycling stability with a delithiation capacity of 166.8 mAh g−1 at 500 mA g−1 after 100 cycles. However, the corresponding delithiation capacity of pristine Na2Li2Ti6O14 is only 136.9 mAh g−1 after 100 cycles. Li.33La.56TiO3 modification is a direct and powerful design method to enhance the delithiation and lithiation capacities and cycling stability of Na2Li2Ti6O14.