Electrochemical properties of P2-Na2/3[Ni1/3Mn2/3]O2 cathode material for sodium ion batteries when cycled in different voltage ranges

• Published in: Electrochimica acta 2013-12, Vol.113, p.200-204
• Main Authors: Wang, Hong, Yang, Bingjian, Liao, Xiao-Zhen, Xu, Jing, Yang, Dezhi, He, Yu-Shi, Ma, Zi-Feng
• Format: Article
• Language: English
• Subjects: Cathode material; Cathodes; Constraining; Crystal structure; Cycles; Cycling performance; Electric batteries; Electric potential; P2-Na2/3[Ni1/3Mn2/3]O2; Sodium; Sodium ion battery; Voltage
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2013.09.098

•P2-Na2/3[Ni1/3Mn2/3]O2 was synthesized via spray drying method and a two step solid state process.•Cycling performance of P2-Na2/3[Ni1/3Mn2/3]O2 cathode was studied in different voltage ranges.•The prepared material showed excellent reversibility between 2.0V and 4.0V with good capacity retention.•Cycled in 2.0–4.5V, the crystal structure of P2-Na2/3[Ni1/3Mn2/3]O2 was irreversibly damaged.•The discharge capacities increased to 134.7mAg−1 (0.1C) and 107.8mAg−1 (1C), cycled in 1.6–3.8V. P2-type Na2/3[Ni1/3Mn2/3]O2 cathode material has been synthesized via spray drying method and a two step solid state process. Electrochemical behavior of the prepared material as cathode material for sodium ion battery was investigated in different charge-discharge voltage ranges. The results indicated that the cycling performance of the P2-Na2/3[Ni1/3Mn2/3]O2 cathode greatly depended on the voltage window. The material showed excellent reversibility between 2.0V and 4.0V with reversible capacity of 86mAhg−1 (0.1C) and 77mAhg−1 (1C). XRD analyses indicated that crystal structure of the P2-type Na2/3[Ni1/3Mn2/3]O2 could be well maintained after long term cycling in 2.0–4.0V. When the upper limiting voltage was increased to 4.5V, the crystal structure of P2-Na2/3[Ni1/3Mn2/3]O2 was irreversibly damaged due to over extraction of Na+ in 4.0–4.5V. On the other hand, when the cycling voltage range was between 1.6V and 3.8V, the discharge capacities increased to 135 mAh g−1 (0.1C) and 108mAhg−1 (1C), respectively. However, the cycling stability in 1.6–3.8V was not as excellent as that in 2.0–4.0V. This maybe due to the lattice stress caused by the over insertion of Na+ in the structure at lower voltage.