Spinel-layered Li1.1[Mn0.6Co0.8Ni0.6]O4-σ nanocrystals: Synthesis and electrochemistry at high potentials

• Published in: Journal of solid state chemistry 2020-08, Vol.288 (C), p.121365, Article 121365
• Main Authors: Hu, Linhua, Yin, Liang, Hassan, Fayyazul, Cabana, Jordi
• Format: Article
• Language: English
• Subjects: Ex situ XANES; High potential; Hydrothermal synthesis; Li1.1[Mn0.6Co0.8Ni0.6]O4-σ; Redox mechanism; Spinel-layered structure
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2020.121365

Multinary transition metal compounds are important cathode materials in Li-ion batteries. The most representative compounds can be catalogued under two main structural families: layered and spinel, with the former having high capacity, but the latter showing greater stability. Synergies are frequently sought by integrate both structures into a composite. The combination of Co, Mn and Ni in these structures leads to the large capacity and operation at high voltage. However, these mixed compounds are mainly synthesized at high temperature and relatively long times. The resulting thermodynamic control makes it difficult to tailor structure, morphology and surface chemistry through metastability. In this context, hydrothermal methods emerge as an attractive pathway of synthesis that could open new up new material permutations, but their versatility toward complex oxide cathodes has not been fully exploited. As a step in this direction, we demonstrate the synthesis of Li1.1[Mn0.6Co0.8Ni0.6]O4-σ with a spinel-layer structure and investigated its electrochemistry and redox mechanisms at high potentials. This strategy expands the current library of cathode materials and brings new opportunities for materials design. [Display omitted] A new spinel-layer compound Li1.1 [Mn0.6Co0.8Ni0.6]O4-σ was directly synthesized via a hydrothermal process. The compound delivers a capacity of ~149mAh/g as battery electrode. Reversible redox of Ni2+/Ni4+ and Co3+/Co4+ was realized by ex situ XANES for electrodes with different status, with hysteretic activation of Mn4+ during the first cycle. •Hydrothermal synthesis for a new compound Li1.1 [Mn0.6Co0.8Ni0.6]O4-σ with spinel-layer structure.•Synchrotron powder X-ray diffraction pattern and atomic-resolution HAADF-STEM images.•Ex situ XANES characterization for electrodes harvested with different status.•Reversible Ni2+/Ni4+ and Co3+/Co4+ redox in the spinel-layer compound.