Extensive migration of Ni and Mn by lithiation of ordered LiMg0.1Ni0.4Mn(1.5)O4 spinel.
Li(x)Mg(0.1)Ni(0.4)Mn(1.5)O(4) spinel (P4(3)32) was chemically and electrochemically lithiated in the range 1 < x <or= 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 approximately 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 TiO(2).
Interfaculty Reactor Institute, Delft University of Technology, The Netherlands. m.wagemaker@iri.tudelft.nl
Marnix
M
Wagemaker
Frans G B
FG
Ooms
Erik M
EM
Kelder
Joop
J
Schoonman
Gordon J
GJ
Kearley
Fokko M
FM
Mulder