Structure and electrochemical properties of Li1+yNi0.5AlxMn0.5−xO2 synthesized by a new sol-gel method

Layered Li-Ni-Mn-O compounds were successfully synthesized via a new sol-gel method at 950 °C in air, in which citric acid as chelating agent makes it possible to intermix cations in atomic scale and, therefore, leads to homogeneous and fine oxide products. Substitution of Al3+ and/or Li+ ion was shown to prevent the structural degradation of the electrode material allowing a higher discharge capacity. Li1+yNi0.5AlxMn0.5−xO2 doped with 5 mol% Al exhibited a discharge capacity of 192 mAh g−1 at 2.5-4.7 V with 4% capacity loss after 30 cycles. An addition of 8 mol% Li+ showed a smaller voltage drop and improved the capacity retention.