Composite cathode materials produced by integrating isostructural (2D-layered) compounds LiNiO 2 , LiCoO 2 , and Li 2 MnO 3 (Li(Li 1/3 Mn 2/3 )O 2 ) have been investigated utilizing a compositional phase diagram. The samples were characterized by multiple techniques to establish structure-property relationships. Specifically, for structural characterization, powder X-ray diffraction, scanning electron microscopy, thermo-gravimetric analysis, and X-ray photoelectron spectroscopy were carried out. For properties, electrochemical characterization was carried out. The best composition showed a discharge capacity of 244 mAh/g (C/15 rate) in the testing range of 4.6-2 V, with good coulombic efficiency and cyclability.

Abstract:There is ongoing effort to identify novel materials that have performance better than LiCoO 2 . The objective of this work is to explore materials in the system (1 -x -y) LiNi 0.8 Co 0.2 O 2 • xLi 2 MnO 3 • yLiCoO 2 . A ternary composition diagram was used to identify sample points, and compositions for testing were initially chosen. Detailed characterization of the synthesized materials was done, including Rietveld Refinement of XRD data, XPS analysis for valence state of transition-metals, SEM for microstructure details, and TGA for thermal stability of the materials. Electrochemical performance showed that discharge capacities on the order of 230 mAh/g were obtained. Preliminary results showed that these materials exhibit good cycling capabilities thereby positioning these materials as promising for Li-ion battery applications.