Electrochemical Characteristics of Co-Substituted α- and β-Li(5)AlO(4) as High-Specific Capacity Positive Electrode Materials

[Image: see text] Electric vehicles and hybrid electric vehicles require batteries with higher energy densities than conventional batteries. Anion redox-type active materials have been proposed as new high-capacity positive electrode materials for Li-ion batteries with high-energy densities. Co-substituted Li(5)AlO(4) is a novel and promising high-capacity positive electrode material for Li-ion batteries. In this study, we investigated the influence of different synthesis conditions on the enhancement of the specific capacity. The material prepared via mechanical alloying of β-Li(5)AlO(4) with LiCoO(2) at 300 rpm for 24 h exhibited a higher specific capacity than that prepared from α-Li(5)AlO(4) and LiCoO(2). Co-substituted β-Li(5)AlO(4) demonstrated a specific capacity of approximately 250 mA h g(–1). The specific capacity of Co-substituted α and β-Li(5)AlO(4) increased with increasing Co content in the samples. According to X-ray absorption near edge structure measurements, the irreversible oxygen redox reaction and a reversible reaction involving the formation and consumption of peroxide were responsible for the charge compensation of Co-substituted β-Li(5)AlO(4) and α-Li(5)AlO(4), respectively.