Synthesis and Properties of LiNi_(0.5)Mn_(0.5)O_2 Cathode Compound prepared by Successive Freeze-drying and Self-ignition

摘要

LiNi_(0.5)Mn_(0.5)O_2 samples were prepared by a method involving successive freeze-drying and auto-ignition of an aqueous solution of metallic cations and hydroxypropylmethyl cellulose (HPMC). Single-phase compounds could be obtained by thermal treatment of the precursor at 950°C during 1 hour. The influence of a Li excess on the properties of the material was studied by X-ray diffraction (Rietveld analysis), electron microscopy and electrochemical characterization. It was found that increasing the nominal Li excess leads to a slight decrease of the crystallographic cell parameters, a small increase of the average grain size and an improvement of the electrochemical properties.