Lanthanide doping induced electrochemical enhancement of Na(2)Ti(3)O(7) anodes for sodium-ion batteries

Na₂Ti₃O₇ is considered as a promising anode material for sodium ion batteries (SIBs) due to its excellent high-rate performance compared with hard carbons. However, the electrochemical performance of Na₂Ti₃O₇ is heavily limited by its low electrical conductivity. In this study, we synthesized a series of lanthanide (Ln = La, Ce, Nd, Sm, Gd, Er, and Yb) doped microsized Na₂Ti₃O₇ anode materials and systematically studied the electrochemical performance. Compared with pristine Na₂Ti₃O₇, all the doped samples show superior electrochemical performance. Especially, the Yb³⁺ doped sample not only delivers a high reversible capacity of 89.4 mA h g⁻¹ at 30C, but also maintains 71.6 mA h g⁻¹ at 5C after 1600 cycles, nearly twice that of pristine Na₂Ti₃O₇. It is found for the first time that the enhancement in doped samples is attributed to the introduction of lanthanides which induces lattice distortion and oxygen vacancies.Jiale Xia, Hongyang Zhao, Wei Kong Pang, Zongyou Yin, Bo Zhou, Gang He, Zaiping Guo and Yaping D