Synthesis of spinel LiNi0.5Mn1.5O4 with secondary plate morphology as cathode material for lithium ion batteries

Spinel LiNi0.5Mn1.5O4 material has been synthesized by a spray drying process and subsequent solid state reaction. Polyvinylpyrrolidone (PVP) is given as additive to the spray drying precursor solution and its effects on structural and electrochemical properties are evaluated. By using PVP in the synthesis process, the obtained sample displays a secondary plate morphology which is consisting of densely arranged primary octahedrally shaped particles. The new cathode material has a lesser degree of impurity phases, a higher discharge capacity, a superior rate capability, and a slightly better cycling performance than the sample synthesized without PVP. In more detail, by the use of PVP the ratio of Mn3+ to Mn4+ in the final product decreases from 20.8 to 9.2%. The initial discharge capacity at 0.1 C exhibits an increase of about 14%. The normalized capacity at 20 C is 84.1% instead of 67.0%. A slightly improved cycling performance with the capacity retention increase from 93.8 to 97.9% could be observed as well.