Theoretical research into low-voltage Na_(2)TiSiO_(5)anode for lithium-ion battery

Na_(2)TiSiO_(5)(NTSO)is a low-cost Li-ion battery anode with great application potential,such as the tetragonal NTSO(T-NTSO)with a high capacity and a low voltage.In addition to the tetragonal structure,NTSO has two other polymorphs.However,the basic understanding of the structure,ion insertion and transport mechanisms of these new materials is still lacking.Herein,we present a combined experimental and computational investigation of the tetragonal and orthorhombic NTSO to reveal the intrinsic mechanism leading to the superior electrochemical performance of T-NTSO.We determined that the insertion site with a flexible Ti^(4+)/Ti^(3+)redox pair is critical for Li+insertion stability.The large number of such flexible sites in the T-NTSO results in a higher capacity and higher ionic conductivity than those of orthorhombic polymorph.The understanding of intrinsic properties will accelerate the development and utilization of titanosilicates as the next generation low-voltage anode of Li-ion battery.