O3-NaFe(1/3- x)Ni1/3Mn1/3Al x O2 Cathodes with Improved Air Stability for Na-Ion Batteries

Xiaowei Li; Xing Shen; Junmei Zhao; Yang Yang; Qiangqiang Zhang; Feixiang Ding; Miao Han; Chunliu Xu; Chao Yang; Huizhou Liu; Yong-Sheng Hu

doi:10.1021/acsami.1c07554

O3-NaFe_{(1/3- x)}Ni_1/3Mn_1/3Al _x O₂ Cathodes with Improved Air Stability for Na-Ion Batteries

ACS Appl Mater Interfaces. 2021 Jul 21;13(28):33015-33023. doi: 10.1021/acsami.1c07554. Epub 2021 Jul 9.

Authors

Xiaowei Li^{1

2}, Xing Shen^{1

2}, Junmei Zhao^{1

3

2}, Yang Yang^{4

2}, Qiangqiang Zhang^{4

2}, Feixiang Ding^{1

2}, Miao Han⁵, Chunliu Xu¹, Chao Yang¹, Huizhou Liu¹, Yong-Sheng Hu⁴

Affiliations

¹ CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.
³ Innovation Academy for Green Manufacture, Chinese Academy of Sciences, Beijing 100190, China.
⁴ Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
⁵ Beijing Institute of Technology, Chongqing Innovation Center, Chongqing, 401120, China.

PMID: 34240842
DOI: 10.1021/acsami.1c07554

Abstract

Na-ion batteries (NIBs) have been considered as potential candidates for large-scale energy storage, where O3-type Na-based layered oxide cathodes have attracted great attention due to their high capacity and low cost. However, O3-Na_xTMO₂ materials still suffer from insufficient air stability, which could lead to deteriorative electrochemical properties and thus hinder their practical application. In this work, a series of Al-doped O3-NaFe_(1/3-x)Ni_1/3Mn_1/3Al_xO₂ cathodes prepared by a co-precipitation method were investigated to enhance their electrochemical performance and air stability through stabilizing their structural and interface chemical properties. The Al-doped O3-NaFe_(1/3-0.01)Ni_1/3Mn_1/3Al_0.01O₂ (NFNMA_0.01) cathode delivers a comparable capacity of 138 mAh g^-1 and keeps a capacity retention of 85.88% after 50 cycles at 0.2 C, while the undoped O3-NaFe_1/3Ni_1/3Mn_1/3O₂ (NFNM) can only keep a capacity retention of 71.02%, although with an initial capacity of 141 mAh g^-1 at 0.2 C. For the air stability, the capacity decay rates are 58.87 and 5.07% for the undoped NFNM and Al-doped NFNMA_0.01 after the air exposure for 30 days, respectively. The greatly decaying electrochemical performance could be due to the formation of carbonates during air exposure, which can be efficiently suppressed by Al doping. The doped Al³⁺ has been confirmed to be inserted into the NFNM crystal lattice, inducing the reduced values of lattice parameters a and c due to the smaller ionic radius of Al³⁺ (53.5 pm) vs Fe³⁺ (55.0 pm). This study demonstrates that Al doping plays an important role in the air stability and cycling stability for layered cathode materials, which offers an efficient strategy to optimize the material design for their practical application in NIBs.

Keywords: Al doping; Na-ion batteries; O3-NaFe(1/3−x)Ni1/3Mn1/3AlxO2; air stability; layered oxide cathodes.