The embedded transition metal layered oxide (AMOâ‚‚, A = Li⺠or Naâº, M = transition metal) has long been considered a key cathode material for lithium and sodium ion batteries. Traditionally, the redox reactions of transition metals were believed to provide charge compensation during ion deintercalation, limiting the capacity of the material. However, this view was challenged with the discovery of lithium-rich layered oxides, such as O3-structured Li[Liâ‚“Mâ‚â‚‹â‚“]Oâ‚‚, which exhibit ultra-high reversible capacities—often exceeding 300 mAh/g. These materials revealed that lattice oxygen can also participate in the electron-loss process, contributing significantly to the overall capacity.
This phenomenon is not unique to lithium-rich materials; many layered oxides show similar behavior, where oxygen plays a role in charge compensation. Yet, understanding how oxygen undergoes reversible redox and how its oxidation state changes remains a critical challenge in battery research. The relationship between crystal structure and oxygen redox activity is essential to unraveling the underlying mechanisms.
Recently, Associate Professor Yan Xiqian and Researcher Hu Yongsheng from the Institute of Physics, Chinese Academy of Sciences, published a groundbreaking study titled "Structure-Induced Reversible Anionic Redox Activity in Na Layered Oxide Cathode" in *Joule*, a leading journal in energy research. Collaborating with scientists from Oak Ridge National Laboratory, Brookhaven National Laboratory, Lawrence Berkeley National Laboratory, and the Stanford Linear Accelerator Center, they used advanced techniques like neutron scattering and synchrotron radiation to investigate the sodium ion battery cathode material P3-Na₀.₆[Li₀.₂Mn₀.₈]O₂.
Their research revealed the structural basis for reversible oxygen redox in this material. By combining neutron pair distribution function (nPDF) analysis with X-ray and neutron diffraction, they observed short-range structural changes that confirmed the reversible bulk phase transitions caused by oxygen redox. This work marked the first time such structural changes related to oxygen charge compensation were studied in detail.
The study showed that after charging, the material retained a P-phase layered structure, despite significant stacking faults. Importantly, the oxygen occupancy remained at 1, indicating minimal loss of lattice oxygen. The researchers concluded that the P-phase's large interlayer spacing allows it to accommodate distortions caused by changes in O–O bond lengths. Additionally, this spacing helps prevent cation migration into the alkali metal layer during charging, thus maintaining a stable layered structure and enabling reversible oxygen redox.
This research not only clarifies the mechanism behind reversible oxygen redox but also opens new pathways for designing high-voltage, high-capacity cathode materials with stable and reversible oxygen behavior. The use of nPDF as a powerful analytical tool expands the scope of structural studies in battery materials.
The study was supported by several key projects, including the 973 Program of the Ministry of Science and Technology, the National Science Fund for Distinguished Young Scholars, the National Natural Science Foundation Innovation Research Group, and the Chinese Academy of Sciences Hundred Talents Program.
Flat Single Axis Solar Tracker System
Flat Single Axis Solar Tracker System,Single Axis Solar Tracker System,Single Axis Solar Tracker System customization
Hebei Jinbiao Construction Materials Tech Corp., Ltd. , https://www.pvcarportsystem.com