A Low-Voltage Layered Na2TiGeO5 Anode for Lithium-Ion Battery

Titanium-based anode materials have achieved much progress with the wide studies in lithium-ion batteries. However, these known materials usually possess high discharge voltage platforms and limited energy densities. Herein, a titanium-based oxide of Na2TiGeO5 with layered structure, two-dimensional lamellar frame and exposed highly active (001) facet, exhibiting good electrochemical performance in terms of high capacity (410 mAh g(-1) with a current density of 50 mA g(-1)), excellent rate capability and cycling stability with no obvious capacity attenuation after 4000 cycles, is reported. The appropriate discharge voltage plateau at around 0.2 V endows the Na2TiGeO5 anode material high security compared with graphite and high energy density compared with spinel Li4Ti5O12. Combining the electrochemical tests and the density functional theory calculations, the Li+ storage mechanism of Na2TiGeO5 is elucidated and the conversion reaction process is revealed. More importantly, this study provides a way to develop low-voltage and high-capacity titanium-based anode materials for efficient energy storage.