Preparation, electrochemical characterization and in-situ kinetic observation of Na2Li2Ti6O14 as anode material for lithium ion batteries

Abstract A novel lithium storage material Na 2 Li 2 Ti 6 O 14 is synthesized and reported as anode material for lithium-ion batteries in this paper. The synthesis of Na 2 Li 2 Ti 6 O 14 is performed by using a simple solid state reaction route. No impurity can be detected in the final product obtained at a temperature of 900 °C. As-formed Na 2 Li 2 Ti 6 O 14 is composed of irregular solid particles with the size ranging from 200 to 400 nm. Using as anode material, Na 2 Li 2 Ti 6 O 14 exhibits flat lithiation/delithiation plateaus with average working potential of 1.28 V. Electrochemical testing results show that Na 2 Li 2 Ti 6 O 14 can deliver a reversible capacity of 74 mA h g −1 with capacity retention of 98.01% upon 50 cycles. Moreover, it also displays excellent rate performance with a charge capacity of 69.5 mA h g −1 at 200 mA g −1 , 64.7 mA h g −1 at 300 mA g −1 , 60.7 mA h g −1 at 400 mA g −1 , and 57.9 mA h g −1 at 500 mA g −1 . The outstanding kinetic behavior is attributed to the high lithium ion diffusion coefficient in Na 2 Li 2 Ti 6 O 14 , which shows the value ranging from 10 −14 to 10 −12 cm 2 s −1 . Owing to the rapid diffusion kinetics, symmetrical structural change at high rates can be observed by in-situ X-ray diffraction during charge–discharge process.