Soft mechanochemically assisted synthesis of nano-sized LiCoO2 with a layered structure

Abstract

Soft mechanochemically assisted reaction between CoOOH and LiOH·H2O at 400 °C yields O3-layered LiCoO2 with nanometric particle sizes of 20–30 nm. The interaction of CoOOH with LiOH·H2O is monitored by DTA and TGA analysis. XRD powder and TEM analysis is used for structural and morphological characterization of the precursors and target LiCoO2. Soft mechanochemical treatment of the CoOOH–LiOH·H2O mixture leads to amorphization of the lithium salt, while CoOOH remains intact. In addition, a partial exchange of protons from CoOOH with lithium takes place. Thermal treatment at 400 °C of the mechanochemically treated mixture yields layered LiCoO2 with a small amount of a spinel-type Li2+yCo2−yO4 phase (less than 2%). The morphology of LiCoO2 inherits the morphology of CoOOH in the precursor. Layered LiCoO2 displays thin nanometric particles with a narrow particle size distribution: more than 50% of particles are distributed between 20 and 30 nm. The electrochemical extraction and insertion of lithium in nano-sized LiCoO2 is examined in model lithium cells using a galvanostatic mode.