Mechanochemical Engineering of Polymer-Coated Silicate Nanocrystal Cathodes

摘要

Lithium iron silicate has attracted a lot of attention due to its 330 mAh g~(-1) theoretical capacity (2 Li~+ per formula unit). However, inherently it exhibits relatively poor Li-ion intercalation kinetics, interfacial reactivity and complex phase transitions resulting in lower than one Li~+storage and poor capacity retention. In this work, we report a core-shell strategy to overcome these obstacles making use of mechanochemical processing and polymer coating. Mechanochemical annealing has been sown recently to lead to activation of Li-ion diffusion (D_(Li)) by one order of magnitude enhancement. Subsequently, in situ conductive polymer coating was employed on the surface of nanocrystals via an ambient temperature chemical process. As a result of this integrated nanocrystal engineering approach the core-shell LFS@P (β_(II)) cathode material delivered >1.3 Li and substantially enhanced cycling stability.