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

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.