Cr3+-Doped TiNb2O7 as an advanced anode material for high-performance lithium-ion batteries

Abstract

Because of its high operating potential (ca. 1.6 V), high theoretical capacity (ca. 387 mA h/g), and safety of operation, TiNb2O7 (TNO) is a promising anode material and an excellent alternative to spinel Li4Ti5O12. To overcome the poor electrical conductivity and low Li+ ion diffusion coefficient of pure TNO, and, thereby, significantly improve its rate performance, in this study we prepared a novel Ti1–xCrxNb2O7 (x = 0.05; Cr-TNO) anode material. When evaluated for its energy storage performance, the electrochemical properties of Cr-TNO were improved relative to those of TNO, including an excellent rate capability (178.2 mA h/g at 10C) and good cycle stability (84.2 % retention after 500 cycles), due to enhanced electronic and ionic conductivities. Furthermore, we demonstrate herein the practical applications of Cr-TNO when combined with active carbon and a LiNi0.5Mn1.5O4 cathode in an asymmetric supercapacitor and a full lithium-ion battery, respectively. Both of these devices possessed pronounced cycling stability and rapid charge/discharge characteristics, reflecting the excellent electrochemical performance of Cr-TNO.