Synthesis and electrochemical characterization of LiNi{sub 1{minus}y}Co{sub y}O{sub 2} powders obtained by complex sol-gel process

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{sub 2} and LiCoO{sub 2} oxides and their solid solutions have been extensively studied as they (and the LiMn{sub 2}O{sub 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{sub 1{minus}x}Co{sub x}O{sub 2} have attracted the attention as alternative cathodes to the state of art LiCoO{sub 2} in commercial rechargeable Li-ion batteries. Here the authors have used the Complex Sol-Gel Process (CSGP) to prepare LiNi{sub 1{minus}x}Co{sub x}O{sub 2} (x = 0, 0.25, 0.5, 0.75, 1). Starting sols were prepared from Li{sup +}-(1{minus}x)Ni{sup 2+}-xCo{sup 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 acetate solutions were first alkalized by ammonia and then the ascorbic acid was added. Regular sols were concentrated to 1/3 of their initial volume and dried slowly up to 170 C. Thermal transformation of the gels to solids was studiedmore » by XRD and IR. The electrochemical properties of the compound LiNi{sub 0.75}Co{sub 0.25}O{sub 2} prepared by the Route-A were evaluated and reported.« less