In-situ neutron diffraction study of the xLi2MnO3(1-x)LiMO2 (x=0,0.5; M=Ni, Mn, Co) layered oxide compounds during electrochemical cycling

The layered oxide compounds xLi2MnO3$(1 x)LiMO2 (M 1⁄4 Ni, Mn, Co) are of great interest as positive electrode materials for high energy density lithium-ion batteries. In-situ neutron diffraction was carried out to compare the structural changes between the classical layered compound Li[Ni1/3Mn1/3Co1/3]O2 (x 1⁄4 0) and lithium-excess layered compound Li[Li0.2Ni0.18Mn0.53Co0.1]O2 (x 1⁄4 0.5) during electrochemical cycling. In this work, lab made pouch cells were built for the in-situ study and graphite was used as the anode material. Irreversible structural change of Li[Li0.2Ni0.18Mn0.53Co0.1]O2 during first charge (4.7 V)/ discharge cycle (2.0 V) was indicated by dynamic changes in lattice d-spacing, while the Li[Ni1/3Mn1/ 3Co1/3]O2 showed completely reversible structural evolution between 4.4 V and 2.5 V. Ex-situ neutron powder diffraction was performed on both pristine and chemically delithiated lithium-excess layered compounds to better understand the irreversible structure change. 2013 Published by Elsevier B.V.