High Lithium Insertion Voltage Single-Crystal H2Ti12O25 Nanorods as a High-Capacity and High-Rate Lithium-Ion Battery Anode Material

摘要

H2Ti12O25 holds great promise as a high-voltage anode material for advanced lithium-ion battery applications. To enhance its electrochemical performance, control of the crystal orientation and morphology is an effective way to cope with slow Li+-ion diffusion inside H2Ti12O25 with severe anisotropy. In this report, Na2Ti6O13 nanorods, prepared from Na2CO3 and anatase TiO2 in molten NaCl medium, were used as a precursor in the synthesis of long single-crystal H2Ti12O25 nanorods with reactive facets. The as-prepared H2Ti12O25 nanorods with a diameter of 100-200nm showed higher charge (extraction) specific capacity and better rate performance than previously reported systems. The reversible capacity of H2Ti12O25 was 219.8mAhg(-1) at 1C after 100cycles, 172.1mAhg(-1) at 10C, and 144.4mAhg(-1) at 20C after 200cycles; these values are higher than those of H2Ti12O25 prepared by the conventional soft-chemical method. Moreover, the as-prepared H2Ti12O25 nanorods exhibited superior cycle stability with more than 94% retention of capacity with nearly 100% coulombic efficiency after 100cycles at 1C. On the basis of the above results, long single-crystal H2Ti12O25 nanorods synthesized in molten NaCl with outstanding electrochemical characteristics hold a significant amount of promise for hybrid electric vehicles and energy-storage systems.