Polymorphism-Controlled Electrochemical Energy Storage Performance of LiNbWO6

Different atomic arrangements lead to the changes of the electronic structures, which in turn affect the voltages, the diffusion dynamics, and relevant electrochemical properties of the materials. In this study, the inherent properties and lithium storage mechanism of polymorphic LiNbWO 6, tetragonal and hexagonal phases, are investigated in detail via experimental techniques and density functional theory calculations. The specific capacity of LiNbWO 6 -T at a high mass loading of about 10 mg cm –2 is 200.4 mA h g –1, and its Coulombic efficiency is 90.5% at 100 mA g –1 . Conversely, the reversible capacity of LiNbWO 6 -H is only 20.5 mA h g –1 with a Coulombic efficiency of 70.3% at 50 mA g –1 . Our experiments show that tetragonal LiNbWO 6 manifests higher specific capacity, faster Li-ion storage kinetics, and superior electrochemical performance in comparison to the hexagonal phase. The results suggest that tetragonal LiNbWO 6 is a promising host for highly efficient lithium storage applications.