Copper and Zirconium Codoped O3-Type Sodium Iron and Manganese Oxide as the Cobalt/Nickel-Free High-Capacity and Air-Stable Cathode for Sodium-Ion Batteries
Yamin Zheng, Xiaobao Huang, Xiao‐Meng Meng, Shoudong Xu, Liang Chen, Shibin Liu, Ding Zhang
Abstract
Considering the abundance of iron and manganese within the Earth’s crust, the cathode O3-NaFe0.5Mn0.5O2 has shown great potential for large-scale energy storage. Following the strategy of introducing specific heteroelements to optimize the structural stability for energy storage, the work has obtained an O3-type NaFe0.4Mn0.49Cu0.1Zr0.01O2 that exhibits enhanced electrochemical performance and air stability. It displays an initial reversible capacity of 147.5 mAh g–1 at 0.1C between 2 and 4.1 V, a capacity retention ratio exceeding 69.6% after 100 cycles at 0.2C, and a discharge capacity of 70.8 mAh g–1 at a high rate of 5C, which is superior to that of O3-NaFe0.5Mn0.5O2. The codoping of Cu/Zr reserves the layered O3 structure and enlarges the interlayer spacing, promoting the diffusion of Na+. In addition, the structural stability and air stability observed by Cu-doping is well maintained via the incorporation of extra Zr favoring a highly reversible phase conversion process. Thus, this work has demonstrated an efficient strategy for developing cobalt/nickel-free high-capacity and air-stable cathodes for sodium-ion batteries.