Dongli Zeng

From Grey Lab Page

My research has focused on the structural analysis of cathode materials for lithium-ion batteries. Various techniques including X-ray and neutron diffraction (XRD/ND), X-ray Absorption Near Edge Structure (XANES), ^6/7Li NMR spectroscopy and neutron Pair Distribution Function (PDF) analysis along with Reverse Monte Carlo (RMC) calculations, have been employed to investigate the local and long range structure for these compounds. Series Li[Ni_yMn_yCo_1-2y]O₂ (0.02≤y≤0.30) and Sr₂MnO₂Cu_2m-0.5S_m+1 (m=1, 2, 3) family are the two systems I am currently working on.

Li[Ni_yMn_yCo_1-2y]O₂ (0.02≤y≤0.30) are layered compounds as promising alternatives to LiCoO₂, which is the most widely used cathode material in common commercial lithium ion batteries. Cation orderings in these materials is one of the most concerned questions since it is closely related to their electrochemical behaviors. A systematic and intensive study has been performed on the pristine samples to investigate the local and long range structure for this series of compounds and the Ni/Mn clustering tendency was revealed. Furthering works in probing the structure changes during the charging/discharging processes for these materials are undergoing. A more recent work is on novel materials, layered oxysulfides Sr₂MnO₂Cu_2m-0.5S_m+1 (m=1, 2, 3). These compounds contain alternating Sr₂MnO₂ layers and copper sulfide layers of varying thickness. Solid state NMR, XRD, Neutron Diffraction and XAS were combined to study their electrochemical behaviors from different aspects.