Extensive Migration of Ni and Mn by Lithiation of Ordered LiMg0.1Ni0.4Mn1.5O4 Spinel

• Published in: Journal of the American Chemical Society 2004-10, Vol.126 (41), p.13526-13533
• Main Authors: Wagemaker, Marnix, Ooms, Frans G. B, Kelder, Erik M, Schoonman, Joop, Mulder, Fokko M
• Format: Article
• Language: English
• Subjects: Applied sciences; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja048319x

Li x Mg0.1Ni0.4Mn1.5O4 spinel (P4332) was chemically and electrochemically lithiated in the range 1 < x ≤ 2.25 and subjected to detailed X-ray and neutron diffraction analysis to understand the electrochemical behavior in the 3 V region. Extensive migration of Ni and Mn during lithium insertion was found, resulting in the disappearance of the initial Ni−Mn ordering and the formation of Ni-rich and Ni-poor domains, leading to two Jahn−Teller-distorted tetragonal phases with different Ni:Mn ratios. Such extensive Ni and Mn migration was not known for these spinels, and strongly influences the initial cycling behavior. The newly formed tetragonal phase with a Ni:Mn ratio of ∼0.07 has a higher cyclability and a higher capacity, and is therefore suggested to have a favorable composition for this intercalation range, as is confirmed in the literature. In addition, lithium is found to occupy multiple positions inside the distorted oxygen octahedron of this phase, a finding previously known only for lithium in anatase TiO2.