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Structural Transformation of Li-Excess Cathode Materials via Facile Preparation and Assembly of Sonication-Induced Colloidal Nanocrystals for Enhanced Lithium Storage Performance
journal contribution
posted on 2017-08-22, 00:00 authored by Jianqing Zhao, Ruiming Huang, Pablo Ramos, Yiying Yue, Qinglin Wu, Michele Pavanello, Jieyu Zhou, Xiaoxiao Kuai, Lijun Gao, Huixin He, Ying WangA surfactant-free
sonication-induced route is developed to facilely prepare colloidal
nanocrystals of Li-excess layered Li1.2Mn0.54Ni0.13Co0.13O2 (marked as
LMNCO) material. The sonication process plays a critical role in forming
LMNCO nanocrystals in ethanol (ethanol molecules marked as EtOHs)
and inducing the interaction between LMNCO and solvent molecules.
The formation mechanism of LMNCO–EtOH supramolecules in the
colloidal dispersion system is proposed and examined by the theoretical
simulation and light scattering technique. It is suggested that the
as-formed supramolecule is composed of numerous ethanol molecules
capping the surface of the LMNCO nanocrystal core via hydrogen bonding.
Such chemisorption gives rise to dielectric polarization of the absorbed
ethanol molecules, resulting in a negative surface charge of LMNCO
colloids. The self-assembly behaviors of colloidal LMNCO nanocrystals
are then tentatively investigated by tuning the solvent evaporation
condition, which results in diverse superstructures of LMNCO materials
after the evaporation of ethanol. The reassembled LMNCO architectures
exhibit remarkably improved capacity and cyclability in comparison
with the original LMNCO particles, demonstrating a very promising
cathode material for high-energy lithium-ion batteries. This work
thus provides new insights into the formation and self-assembly of
multiple-element complex inorganic colloids in common and surfactant-free
solvents for enhanced performance in device applications.