Synthesis and electrochemical characterization of LiNi_1-yCo_yO_2 powders obtained by complex sol-gel process

摘要

The layered oxides, among the wide family of intercalation compounds, have received considerable attention as positive electrode materials in high-energy density lithium and lithium ion batteries. Within this frame LiNiO_2 and LiCoO_2 oxides and their solid solutions have been extensively studied as they (and the LiMn_2O_4 spinels) are the only known materials able to intercalate reversibly lithium at high cell voltage (3.5-4 V). Recently. solid solutions such as LiNi_1-yCo_yO_2 have attracted the attention as alternative cathodes to the state of art LiCoO_2 in commercial rechargeable Li-ion batteries. here we have used the Complex Sol-Gel Process (CSGP) to prepare LiNi_1-xCo_xO_2(x=0,0.25,0.5,0.75,1). Starting sols were prepared from Li~+-(1-x)Ni~2+ -xCo~2+ acetate aqueous solution in two different routes . According to route-A aqueous ammonia was added to a starting solution containing 0.2M ascorbic acid (ASC) on 1m total Me. According to route B the starting aceetate sols were concentrated to 1/3 of their initial volume and dried slowly up to 170 deg C. Thermal transformation of the gels to solids was studied by XRD and IR. The electrochemcial properties of the compound LiNi_0.75Co_0.25O_2 prepared by the Route-A were evaluated and reported.