Well-formed Li1.131Mn0.504Ni0.243Co0.122O2 cathode materials are synthesized via freeze drying followed by a solid state reaction at temperatures of 750–900 °C. Among these oxides, the one synthesized at 800 °C delivers the highest initial discharge capacity of 246.5 mAh g−1 at 0.1 C (1 C = 200 mA g−1) between 2.5 V and 4.8 V. Enhancing the discharge rate to 1 C, initial capacity of 197.8 mAh g−1 is obtained, and 78.8% capacity is retained after 50 cycles. Furthermore, the diffusion coefficients of Li+ in the lithium-rich layered oxide are about 10−14 cm2 s−1 and 10−15 cm2 s−1 for the initial charge platform at 3.90 V and 4.55 V, respectively, determined by galvanostatic intermittent titration technique (GITT). The Li1.131Mn0.504Ni0.243Co0.122O2 prepared by freeze drying is a promising cathode material for lithium ion batteries.