Hierarchically-structured nanocrystalline lithium rich layered composites with enhanced rate performances for lithium ion battery

Li-rich layered composite cathode material: 1/2Li2MnO3∙1/2LiMn1/2Ni1/2O2 with a hierarchically-structured flake morphology is firstly synthesized with a solvent-controlled organic route. X-ray diffraction evidences a pure lithium-rich layered phase of as-fabricated materials. Transmission electron microscopy investigated that each single flake possesses a highly crystalline nature and it composed by numerous hierarchically-structured plates around 20 nm. Electrochemical performances demonstrates that flake cathode delivered a significantly enhanced rate capability as compared to conventional particles prepared by regular co-precipitation method. The specific capacity of flakes cycled at 0.1 and 1 C were 210 and 155 mAh/g, respectively. Cyclic voltammetry represents distinct intercalation mechanisms between two samples, in which a higher lithium diffusivity is derived by flakes with respect to particle ones. Electrochemical impedance profiles shows that the charge-transfer resistances of flake cathodes could be effectively suppressed with respect to particles after cycled at elevated discharge rates. This study provides an alternative approach for synthesizing morphologically-tailored Li-rich layered cathode and virtually proves the ability to tolerant high current input and can preserve a good cycling retention.

This study describes a novel and facile approach to synthesis the morphologically-tailored lithium-rich layered composites with a superior rate capability. As the first accomplishment of flake-like Li-rich layered cathodes, the formation mechanism of the hierarchical layered structure has been proposed and detail discussed. The flake cathode reveals a distinctive lithium intercalation properties and it shows promoted electrochemical performances as compared to regular-shaped Li-rich cathodes fabricated by the conventional method. It successfully proves that the flake-like layered cathode with synthetically-controlled facial orientation is more favorable to sustain elevated current inputs and preserves a good cycling retention. This new synthetic method offers a cost-effectively way via using the alternative solution to achieve morphology-tailored cathode materials. We anticipate that more efforts on the architecture design of Li-rich layered cathodes will be proceeded and ultimately could be applied for advanced energy storage systems of lithium ion battery in the near future.274