title: P2-Type NaxCu0.15Ni0.20Mn0.65O2Cathodes with High Voltage for High-Power and Long-Life Sodium-Ion Batteries.
abstract: Cu-Ni-Mn-based ternary P2-type NaxCu0.15Ni0.20Mn0.65O2(x = 0.50, 0.67, and 0.75) cathodes for sodium-ion batteries (SIBs) are synthesized by a co-precipitation method. We find that Na content plays a key role on the structure, morphology, and the charge-discharge performances of these materials. For x = 0.67 and 0.75, superstructure from Na+-vacancy ordering is observed, while it is absent in the x = 0.50 sample. Despite the same synthesis conditions, materials with x = 0.67 and 0.75 show smaller particle sizes compared to that of the x = 0.50 sample. In addition, redox potentials of the materials differ significantly even though they have the same transition metal ratios. These differences are attributed to the changes in local structures of the as-prepared materials arising from the different amount of Na and possibly oxygen in the lattice. Materials with x = 0.67 and 0.75 show excellent rate performance and cycle stability when tested as cathode material of SIBs. Average discharge potential is as high as 3.41 V versus Na-Na+with capacity of 87 mAh g-1at 20 mA g-1. Excellent capacity and cycle stability are maintained even when they are tested with higher current rates. For instance, a capacity of 62.3 mAh g-1is obtained from the x = 0.67 sample at 1000 mA g-1after 1000 cycles between 3.0 and 4.2 V without any decrease in capacity.
authors: State Key Laboratory of Heavy Oil Processing, College of Science, China University of Petroleum (East China) , Qingdao 266580, People's Republic of China.
authors: Wenpei
authors: W
authors: Kang
authors: Denis Y W
authors: DY
authors: Yu
authors: Pui-Kit
authors: PK
authors: Lee
authors: Zhenyu
authors: Z
authors: Zhang
authors: Haidong
authors: H
authors: Bian
authors: Wenyue
authors: W
authors: Li
authors: Tsz-Wai
authors: TW
authors: Ng
authors: Wenjun
authors: W
authors: Zhang
authors: Chun-Sing
authors: CS
authors: Lee
keywords: P2-type; cathode; high power; long life; sodium-ion battery