Direct Observation of Defect-Aided Structural Evolution in a Nickel-Rich Layered Cathode.
Shuang LiZhenpeng YaoJianming ZhengMaosen FuJiajie CenSooyeon HwangHuile JinAlexander OrlovLin GuShun WangZhongwei ChenDong SuPublished in: Angewandte Chemie (International ed. in English) (2020)
Ni-rich LiNi1-x-y Mnx Coy O2 (NMC) layered compounds are the dominant cathode for lithium ion batteries. The role of crystallographic defects on structure evolution and performance degradation during electrochemical cycling is not yet fully understood. Here, we investigated the structural evolution of a Ni-rich NMC cathode in a solid-state cell by in situ transmission electron microscopy. Antiphase boundary (APB) and twin boundary (TB) separating layered phases played an important role on phase change. Upon Li depletion, the APB extended across the layered structure, while Li/transition metal (TM) ion mixing in the layered phases was detected to induce the rock-salt phase formation along the coherent TB. According to DFT calculations, Li/TM mixing and phase transition were aided by the low diffusion barriers of TM ions at planar defects. This work reveals the dynamical scenario of secondary phase evolution, helping unveil the origin of performance fading in Ni-rich NMC.
Keyphrases
- ion batteries
- transition metal
- solid state
- reduced graphene oxide
- density functional theory
- electron microscopy
- gold nanoparticles
- mycobacterium tuberculosis
- metal organic framework
- single cell
- molecular dynamics
- cell therapy
- molecular dynamics simulations
- mesenchymal stem cells
- high intensity
- molecular docking
- ionic liquid
- solar cells
- liquid chromatography