Synthesis Routes on Electrochemical Behavior of Co-Free Layered LiNi 0.5 Mn 0.5 O 2 Cathode for Li-Ion Batteries.

Co-free layered LiNi 0.5 Mn 0.5 O 2 has received considerable attention due to high theoretical capacity (280 mAh g -1 ) and low cost comparable than LiCoO 2 . The ability of nickel to be oxidized (Ni 2+ /Ni 3+ /Ni 4+ ) acts as electrochemical active and has a low activation energy barrier, while the stability of Mn 4+ provides a stable host structure. However, selection of appropriate preparation method and condition are critical to providing an ideal layered structure of LiNi 0.5 Mn 0.5 O 2 with good electrochemical performance. In this study, Layered LiNi 0.5 Mn 0.5 O 2 has been synthesized by sol-gel and solid-state routes. According to the XRD, the sol-gel method provides a pure phase, and solid-state process only minimize the secondary phases to certain limit. The Ni 2+ /Mn 4+ content in the sol-gel process was higher than in the solid-state reaction, which may be due to the chemical composition homogeneity of the sol-gel samples. Regarding the electrochemical behavior, sol-gel process is better than solid-state reaction. The discharge capacity is 145 mAh/g and 91 mAh/g for the sol-gel process and solid-state reaction samples, respectively.