The effect of compositional change of transition metals on the electrochemical behavior of layered LiMO2 (M=LiwNixCoyMnz) solid solutions

Seven compositions of LiMO2 (M=LiwNixCoyMnz) (w=1/15−1/6; x = 0 − 3/10; y = 1/5 − 1/2; z = 13/30 − 1/3; i.e. w+x+y+z=1) solid solutions were synthesized using the sol–gel method with the following end members LiCoO2, Li2MnO3(Li[Li1/3Mn2/3]O2), and Li[Ni0.5Mn0.5]O2. The electrochemical behavior of the solid solutions was analyzed for the various compositions of metals in transition metal sites. All synthesized particles were semi-spherically shaped with a layered structure. When the content of lithium and cobalt was reduced (while the other metals were increased), the lattice parameters, a and c, decreased and were accompanied by a shift in the Raman spectrum. The cycling studies reveal that the compound, Li[Li1/12Ni1/4Co1/4Mn5/12]O2 was found to be optimal in voltage and from a stability point of view.