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 LiNbWO6, tetragonal and hexagonal phases, are investigated in detail via experimental techniques and density functional theory calculations. The specific capacity of LiNbWO6-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 LiNbWO6-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 LiNbWO6 manifests higher specific capacity, faster Li-ion storage kinetics, and superior electrochemical performance in comparison to the hexagonal phase. The results suggest that tetragonal LiNbWO6 is a promising host for highly efficient lithium storage applications.