Papers by Keyword: Lithium Metal Oxides

Abstract: This article presents a review on Li diffusion in lithium containing metal oxide compounds. The focus is on the investigation of solid state diffusion by tracer methods. In contrast to experiments with Nuclear Magnetic Resonance Spectroscopy and Impedance Spectroscopy, only a limited number of tracer based experiments can be found in the literature. Possible reasons are discussed. Measurements on the system Li-Nb-O are given in detail, while additional results on other Li-M-O (M = Al, Si, Mn, Ti) systems are also presented. The review is completed by a brief survey of the experimental methods in use.

Abstract: One of the aspects most intensively researched in the continuing improvisation of lithium battery is the search for high capacity, high energy density and high performance cathode materials. Substitution of the electroactive elements with heteroatoms is one of the promising methods. In this study, a potential cathode material with a layered structure was successfully synthesized via a sol-gel method. As a comparison, the well-known LiMn_1/3Co_1/3Ni_1/3O₂ (LiMn_0.333Co_0.333Ni_0.333O₂) was also synthesized using exactly the same method and conditions. Both materials were characterized using simultaneous thermogravimetric analysis (STA), X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS). The stoichiometries of the compounds were also confirmed through energy-dispersive X-ray spectroscopy (EDX) measurement. XRD results show that both compounds are single phase and impurity-free with well-ordered hexagonal layered structure characteristics of R-3m space group. Both compounds also show similar morphologies with well-formed crystals and clean surfaces as depicted by the SEM images. XPS measurement reveals that the introduction of chromium into LiMn_1/3Co_1/3Ni_1/3O₂ results in a considerable change in the chemical environment as observed by significant changes in the binding energies (BE) of manganese, cobalt and nickel respectively.

Abstract: LiCoO2 is a well established commercial Li-ion battery cathode. However, due to cost constraints and the toxicity of the metal, other layered compounds should be investigated. In this paper, layered LiMn0.3Co0.3Ni0.3Fe0.1O2 were prepared using sol-gel method with CH3COOLi•2H2O, (CH3CO2)2Mn•4H2O, (CH3CO2)2Co•4H2O, (CH3CO2)2Ni•4H2O and Fe (NO3)3•9H2O as starting materials. The sample was characterized by simultaneous thermogravimetric analysis, x-ray powder diffraction and scanning electron microscopy. The electrochemical characteristics were studied by a charge-discharge cycle done on the fabricated cell using a charge current of 1.0 mA and a discharge current 0.5 mA between 4.2 and 0.5 V. The XRD results showed that the layered LiMn0.3Co0.3Ni0.3Fe0.1O2 were of pure phase with discharge capacity of about 136 mAhg-1. The batteries were then subjected to a series of charge-discharge cycling in the voltage range of 2.5 to 4.2 V. The results showed there was little loss of capacity after 10 cycles.