Electronic Conductivity of LiCoO2 and Its Enhancement by Magnesium Doping

Abstract

LiCoO 2 the active cathode material in commercial rechargeable lithium batteries, is shown to be a p-type semiconductor, associated with the presence of a small concentration of Co 4+ ions. Its conductivity at room temperature can be increased by over two orders of magnitude, to -0.5 S cm -', by partial substitution of Co 3+ by Mg 2+ and compensating hole creation. The electrochemical performance of LiMg,,, 0 Co 0 95 02 is comparable to that of LiCoO 2 ; a small reduction in capacity, associated with a reduction in Co 3+ content, occurs but good reversibility is retained and, in contrast to LiCoO 2 , the Mg-doped material is single phase throughout the charge/discharge cycle.

Intrinsic Electrochemical Characteristics in the Individual Needle-like LiCoO₂ Crystals Synthesized by Flux Growth

“…Many investigations have been carried out to understand the charge and discharge mechanism and improve the electrochemical performance of LIBs. [3][4][5][6][7][8][9][10][11][12][13][14] The LIB electrode is a "composite electrode," composed of active materials, conductive agents, and binders. Therefore, although the electrochemical characteristics of these composite electrodes must be evaluated from the viewpoint of battery engineering, it is not easy to distinguish the intrinsic properties of the active materials from those of the other materials in the composite electrode.…”

Influencia de la síntesis y del grado de dopaje en las propiedades morfológicas, estructurales y electroquímicas de óxidos LiCo_1‑xM_xO₂ (M = Ni, Al, Mg)

“…En la muestra LiCoO 2 se observa una "meseta" a aproximadamente 3.7 V, típica en este material y que está relacionada con un cambio de fase durante la carga y descarga que provoca a la larga una pérdida de ciclabilidad (10). En las muestras dopadas con Ni observamos, en general, que la variación del potencial durante los procesos de inserción y desinsercción es continua y desaparece dicha "meseta", de lo que se deduce que se evitan así los cambios estructurales a lo largo del ciclaje.…”

“…Los resultados encontrados en la bibliografía muestran asimismo que con cátodos LiCo 1-x Al x O 2 se alcanzan mayores voltajes que con LiCoO 2 (4,5). Por otra parte, se ha encontrado que el dopaje con Mg provoca un aumento de la conductividad electrónica del óxido LiCoO 2 (10).…”

Synthesis and Structural Characterization of Lithiated and Delithiated LiCoO2 Using Different Chelating Agents

“…A lot of researches on physical and electrochemical properties of LiCoO 2 have been carried out for the applications of high-energy density electric vehicles (1)(2)(3)(4)(5) . LiCoO 2 is one of the most extensively used cathode material in rechargeable lithium ion batteries.…”