SrLi2Ti6O14: A probable host material for high performance lithium storage

SrLi 2 Ti 6 O 14 is a novel lithium storage host material. In this work, a series of SrLi 2 Ti 6 O 14 are prepared by a simple solid state reaction method at different calcination temperatures and then used as probable host materials for lithium storage. Evaluations of the electrochemical performance in combination with structural analysis suggest that the calcination temperature dramatically affects the phase purity, particle size and lithium storage capability of SrLi 2 Ti 6 O 14 . It can be found that the optimum calcination temperature for SrLi 2 Ti 6 O 14 is 950   °C. SrLi 2 Ti 6 O 14 formed at 950   °C exhibits the highest lithium storage capacity, the fastest lithium-ion diffusion behavior, the best cycling and rate properties among all the five samples. It reveals an initial charge capacity of 170.3   mAh   g −1 at the current density of 50   mA   g −1 . After 50 cycles, the reversible capacity can be kept at 155.9   mAh   g −1 with excellent capacity retention of 91.9%. Even cycled at 300   mA   g −1 , it still can deliver a charge capacity of 141.6   mAh   g −1 . In contrast, the SrLi 2 Ti 6 O 14 formed at 800   °C can only deliver a reversible capacity of 71.5   mAh   g −1 at 300   mA   g −1 . Besides, the electrochemical reaction mechanism between SrLi 2 Ti 6 O 14 and Li is thoroughly investigated by various in-situ and ex-situ techniques. It is found that SrLi 2 Ti 6 O 14 is a zero-strain compound for lithium storage. For the lithium storage process, Rietveld refinement results reveal that lithium ions occupy the 8c, 4b and 4a vacant sites in turns during the discharge process, and the stable framework ensures the structural reversibility during repeated cycles, which is important for SrLi 2 Ti 6 O 14 as a probable host material for high performance lithium-ion batteries.