Embedding MnO@Mn3O4 Nanoparticles in an N‐Doped‐Carbon Framework Derived from Mn‐Organic Clusters for Efficient Lithium Storage

• Published in: Advanced materials (Weinheim) 2018-02, Vol.30 (6), p.n/a
• Main Authors: Chu, Yanting, Guo, Lingyu, Xi, Baojuan, Feng, Zhenyu, Wu, Fangfang, Lin, Yue, Liu, Jincheng, Sun, Di, Feng, Jinkui, Qian, Yitai, Xiong, Shenglin
• Format: Article
• Language: English
• Subjects: anodes; Clusters; Diffusion barriers; Electron energy; Electron energy loss spectroscopy; Embedding; Energy storage; Energy transmission; First principles; Lithium; lithium‐ion batteries; Manganese oxides; Materials science; Mn8 clusters; MnO@Mn3O4 nanoparticles; Nanoparticles; nitrogen‐doped porous carbon frameworks; Pyrolysis; Quantitative analysis; Scanning transmission electron microscopy; Structural stability; Transmission electron microscopy
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201704244

The first synthesis of MnO@Mn3O4 nanoparticles embedded in an N‐doped porous carbon framework (MnO@Mn3O4/NPCF) through pyrolysis of mixed‐valent Mn8 clusters is reported. The unique features of MnO@Mn3O4/NPCF are derived from the distinct interfacial structure of the Mn8 clusters, implying a new methodological strategy for hybrids. The characteristics of MnO@Mn3O4 are determined by conducting high angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) and electron energy loss spectroscopy (EELS) valence‐state analyses. Due to the combined advantages of MnO@Mn3O4, the uniform distribution, and the NPCF, MnO@Mn3O4/NPCF displays unprecedented lithium‐storage performance (1500 mA h g−1 at 0.2 A g−1 over 270 cycles). Quantitative analysis reveals that capacitance and diffusion mechanisms account for Li+ storage, wherein the former dominates. First‐principles calculations highlight the strong affiliation of MnO@Mn3O4 and the NPCF, which favor structural stability. Meanwhile, defects of the NPCF decrease the diffusion energy barrier, thus enhancing the Li+ pseudocapacitive process, reversible capacity, and long cycling performance. This work presents a new methodology to construct composites for energy storage and conversion. The first synthesis of MnO@Mn3O4 nanoparticles embedded in a N‐doped porous carbon framework (MnO@Mn3O4/NPCF) through pyrolysis of mixed‐valent Mn8 clusters indicates unprecedented lithium‐storage performance. The as‐synthesized MnO@Mn3O4 composition is first identified by a combination of atomic‐resolution HAADF‐STEM and EELS valence‐state analyses. This work presents a new methodology to construct composites for energy storage and conversion.