Investigation of local structure in Ni3+-rich Li ion battery cathode materials

LiNi0.8Mn0.1Co0.1O2 (Li NMC 811), LiNi0.6Mn0.2Co0.2O2 (Li NMC 622) and LiNi0.8Co0.15Al0.05O2 (Li NCA) are next generation Li ion battery cathode materials where the main redox active ion is Jahn-Teller active Ni3+. A previous report on the parent material LiNiO2 indicated local ordering of the Ni3+ Jahn-Teller orbitals into trimers at low temperatures, however the impact of the local distortions of the Ni3+ Jahn-Teller orbital on the structure and the subsequent electrochemical performance of these Ni3+ rich materials remains an open question. We propose temperature dependent total scattering measurements on Li NMC 811, Li NMC 622 and Li NCA to investigate the local structure and evolution of the local Jahn-Teller ordering as a function of temperature.

LiNi₀.₈Mn₀.₁Co₀.₁O₂（Li NMC 811）、LiNi₀.₆Mn₀.₂Co₀.₂O₂（Li NMC 622）以及LiNi₀.₈Co₀.₁₅Al₀.₀₅O₂（Li NCA）均为下一代锂离子电池正极材料，其核心氧化还原活性离子为具有姜-泰勒（Jahn-Teller）活性的Ni³+。此前针对母体材料LiNiO₂的研究报道显示，低温下Ni³+的姜-泰勒轨道会发生局域有序排列并形成三聚体；然而，这类富Ni³+材料中，Ni³+姜-泰勒轨道的局域畸变对材料结构及后续电化学性能的影响仍为悬而未决的科学问题。本研究拟对Li NMC 811、Li NMC 622及Li NCA开展温度依赖的全散射测量，以探究局域结构以及姜-泰勒有序结构随温度的演化规律。