Cai Congcong, Li Xinyuan, Li Jiantao, Yu Ruohan, Hu Ping, Zhu Ting, Li Tianyi, Lee Sungsik, Xu Nuo, Fan Hao, Wu Jinsong, Zhou Liang, Mai Liqiang, Amine Khalil
State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070, China.
Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL, 60439, USA.
Nat Commun. 2025 Jan 2;16(1):100. doi: 10.1038/s41467-024-54998-1.
Triggering the anionic redox reaction is an effective approach to boost the capacity of layered transition metal (TM) oxides. However, the irreversible oxygen release and structural deterioration at high voltage remain conundrums. Herein, a strategy for Mg ion and vacancy dual doping with partial TM ions pinned in the Na layers is developed to improve both the reversibility of anionic redox reaction and structural stability of layered oxides. Both the Mg ions and vacancies (□) are contained in the TM layers, while partial Mn ions (~1.1%) occupy the Na-sites. The introduced Mg ions combined with vacancies not only create abundant nonbonding O 2p orbitals in favor of high oxygen redox capacity, but also suppress the voltage decay originated from Na-O-□ configuration. The Mn ions pinned in the Na layers act as "rivets" to restrain the slab gliding at extreme de-sodiated state and thereby inhibit the generation of cracks. The positive electrode, NaMn[Mg□Mn]O, delivers an enhanced discharge capacity and decent cyclability. This study provides insights into the construction of stable layered oxide positive electrode with highly reversible anionic redox reaction for sodium storage.
触发阴离子氧化还原反应是提高层状过渡金属（TM）氧化物容量的有效方法。然而，高电压下不可逆的氧释放和结构劣化仍然是难题。在此，开发了一种镁离子和空位双重掺杂且部分TM离子固定在钠层中的策略，以提高阴离子氧化还原反应的可逆性和层状氧化物的结构稳定性。镁离子和空位（□）都包含在TM层中，而部分锰离子（约1.1%）占据钠位点。引入的镁离子与空位相结合，不仅创造了丰富的非键合O 2p轨道，有利于高氧氧化还原容量，还抑制了源于Na-O-□构型的电压衰减。固定在钠层中的锰离子起到“铆钉”的作用，在极端脱钠状态下抑制板层滑动，从而抑制裂纹的产生。正极NaMn[Mg□Mn]O表现出增强的放电容量和良好的循环稳定性。这项研究为构建具有高度可逆阴离子氧化还原反应的稳定层状氧化物正极用于钠存储提供了见解。
