Beijing Advanced Innovation Center for Materials Genome Engineering, Department of Physical Chemistry, University of Science and Technology Beijing, Beijing, 100083, China.
Institute for Advanced Materials and Technology, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing, 100083, China.
Angew Chem Int Ed Engl. 2023 Apr 3;62(15):e202219230. doi: 10.1002/anie.202219230. Epub 2023 Feb 28.
Manganese-rich layered oxide cathodes of sodium-ion batteries (SIBs) are extremely promising for large-scale energy storage owing to their high capacities and cost effectiveness, while the Jahn-Teller (J-T) distortion and low operating potential of Mn redox largely hinder their practical applications. Herein, we reveal that annealing in argon rather than conventional air is a universal strategy to comprehensively upgrade the Na-storage performance of Mn-based oxide cathodes. Bulk oxygen vacancies are introduced via this method, leading to reduced Mn valence, lowered Mn 3d-orbital energy level, and formation of the new-concept Mn domains. As a result, the energy density of the model P2-Na Mg Mn O cathode increases by ≈50 % benefiting from the improved specific capacity and operating potential of Mn redox. The Mn domains can disrupt the cooperative J-T distortion, greatly promoting the cycling stability. This exciting finding opens a new avenue towards high-performance Mn-based oxide cathodes for SIBs.
钠离子电池（SIB）富锰层状氧化物正极因具有较高的容量和成本效益，在大规模储能方面极具应用前景，但其 Jahn-Teller（J-T）畸变和较低的工作电势严重阻碍了其实际应用。在此，我们揭示了在氩气而非常规空气中退火是一种通用策略，可以全面提升基于锰的氧化物正极的储钠性能。通过这种方法引入体相氧空位，导致 Mn 价态降低，Mn 3d 轨道能级降低，并形成新概念的 Mn 畴。结果，模型 P2-NaMgMnO 正极的能量密度提高了约 50%，这得益于 Mn 氧化还原的比容量和工作电势的提高。Mn 畴可以破坏协同的 J-T 畸变，极大地促进了循环稳定性。这一令人兴奋的发现为 SIB 用高性能基于锰的氧化物正极开辟了新途径。
