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

Abstract The layered oxide compounds x Li 2 MnO 3 ·(1 −  x )LiMO 2 (M = 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[Ni 1/3 Mn 1/3 Co 1/3 ]O 2 ( x  = 0) and lithium-excess layered compound Li[Li 0.2 Ni 0.18 Mn 0.53 Co 0.1 ]O 2 ( x  = 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[Li 0.2 Ni 0.18 Mn 0.53 Co 0.1 ]O 2 during first charge (4.7 V)/discharge cycle (2.0 V) was indicated by dynamic changes in lattice d-spacing, while the Li[Ni 1/3 Mn 1/3 Co 1/3 ]O 2 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.