Low‐Temperature Synthesis of LiNiO2: Reaction Mechanism, Stability, and Electrochemical Properties

Abstract

A thorough study was made concerning the formation of by a low‐temperature ion‐exchange reaction under hydrothermal conditions. with a low degree of cationic mixing and good electrochemical performance was prepared either from pure β‐NiOOH, γ‐NiOOH, or a mixture of both where the γ phase was the majority. The synthesized product presents electrochemical properties similar to prepared by conventional powder synthesis in spite of the difference in Brunauer, Emmett, and Teller (BET) surfaces, around 20 m2/g for and 0.7 m2/g for . The thermal and moisture stabilities of were studied and turned out to be much lower than those of . This moisture instability was found (i) to be intrinsic to , since ground samples presented a similar behavior, (ii) to be enhanced by decreasing the particle size, and (iii) to be much larger than that of . In view of electrochemical applications, cobalt‐substituted products should be used in order to ensure the stability against both reduction‐delithiation and hydrolysis.