Synthesis Routes on Electrochemical Behavior of Co-Free Layered LiNi_0.5Mn_0.5O₂ Cathode for Li-Ion Batteries

Co-free layered LiNi_0.5Mn_0.5O₂ has received considerable attention due to high theoretical capacity (280 mAh g⁻¹) and low cost comparable than LiCoO₂. The ability of nickel to be oxidized (Ni²⁺/Ni³⁺/Ni⁴⁺) acts as electrochemical active and has a low activation energy barrier, while the stability of Mn⁴⁺ provides a stable host structure. However, selection of appropriate preparation method and condition are critical to providing an ideal layered structure of LiNi_0.5Mn_0.5O₂ with good electrochemical performance. In this study, Layered LiNi_0.5Mn_0.5O₂ 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 Ni²⁺/Mn⁴⁺ 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.