Different sodium occupancy sites in P2-layered cathode materials can reorganize Na-ion distribution and modify the Na+/vacancy superstructure, which have a vital impact on the Na-ion transport and Na storage behavior during charge and discharge processes, but have not been investigated specifically and are not yet well understood. Herein, the occupancy ratio of two different Na sites (sites below transition metal ions and sites below oxygen ions along the c direction) in P2-Na0.67[Mn0.66Ni0.33]O2 cathode is tuned successfully by inducing Sb5+ ions with strong repulsion toward Na sites right below transition metals. It is found that the decrease of Na occupancy right below transition metal ions is beneficial to the electrochemical performance of P2-layered cathode materials, regarding cycle stability and rate capability. In situ X-ray absorption spectroscopy reveals that the reversible Mn3.3+/Mn4+ and Ni2+/Ni3+ redox couples provide charge compensation in different voltage regions of 1.8–2.3 and 2.3–4.2 V, respectively. The transmission X-ray microscopy confirms the uniform redox reaction over the whole electrode particle. In addition, Sb substitution can suppress the “P2-O2” phase transition in high voltage region by preventing oxygen gliding in a–b planes, thus ensuring robust structure stability during cycling.
|Journal||Advanced Energy Materials|
|Publication status||Published - 2021 Apr 8|
Bibliographical noteFunding Information:
The work at Fudan University was supported by NSFC (Nos. 52071085 and 51902058), Science & Technology Commission of Shanghai Municipality (No. 19ZR1404200), and China Postdoctoral Science Foundation (No. 2019M651363). The work at Brookhaven National Laboratory was supported by the U.S. Department of Energy, the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies through Advanced Battery Material Research (BMR) program under Contract No. DE‐SC0012704. The authors thank beamline BL14W1 and BL14B1 of Shanghai Synchrotron Radiation Facility, beamline 12BM of Advanced Photon Source at Argonne National Laboratory (Contract No. DE‐AC02‐06CH11357). This research used resources at beamlines 7‐BM (QAS), 18‐ID (FXI), and 28‐ID‐2 of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE‐SC0012704. The authors thank Ning Rui from Chemistry Division at Brookhaven National Laboratory for helping them to carry out XPS measurement.
© 2021 Wiley-VCH GmbH
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)