Operando Lithium Dynamics in the Li‐Rich Layered Oxide Cathode Material via Neutron Diffraction. Issue 7 (25th January 2016)

• Record Type: Journal Article
• Authors: Liu, Haodong; Chen, Yan; Hy, Sunny; An, Ke; Venkatachalam, Subramanian; Qian, Danna; Zhang, Minghao; Meng, Ying Shirley
• Is Part Of: Advanced energy materials. Volume 6:Issue 7(2016)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2016-01-25
• Subjects: energy density -- cathode materials -- lithium dynamics -- lithium‐ion batteries -- neutron diffraction; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.201502143
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract : Neutron diffraction under operando battery cycling is used to study the lithium and oxygen dynamics of high Li‐rich Li(Li x /3 Ni(3/8‐3 x /8) Co(1/4‐ x /4) Mn(3/8+7 x /24) O2 ( x = 0.6, HLR) and low Li‐rich Li(Li x /3 Ni(1/3‐ x /3) Co(1/3‐ x /3) Mn(1/3+ x /3) O2 ( x = 0.24, LLR) compounds that exhibit different degrees of oxygen activation at high voltage. The measured lattice parameter changes and oxygen position show largely contrasting changes for the two cathodes where the LLR exhibits larger movement of oxygen and lattice contractions in comparison to the HLR that maintains relatively constant lattice parameters and oxygen position during the high voltage plateau until the end of charge. Density functional theory calculations show the presence of oxygen vacancy during the high voltage plateau; changes in the lattice parameters and oxygen position are consistent with experimental observations. Lithium migration kinetics for the Li‐rich material is observed under operando conditions for the first time to reveal the rate of lithium extraction from the lithium layer, and transition metal layer is related to the different charge and discharge characteristics. At the beginning of charging, the lithium extraction predominately occurs within the lithium layer. Once the high voltage plateau is reached, the lithium extraction from the lithium layer slows down and extraction from the transition metal layer evolves at a faster rate. Abstract : The lithium and oxygen dynamics of two Li‐rich compounds are investigated and compared via neutron diffraction under operando battery cycling to show the path‐dependent rate of lithium migration from the lithium layer and transition metal layer is asymmetric for charging and discharging revealing the origin of irreversible lithium loss.