Electrochemical Properties of LiNi0.6Co0.2Mn0.2O2 Cathode Materials Prepared with Different Ammonia Content

The content of ammonia coordination agent in initial aqueous solution is one of important factors which greatly influences the morphologies and electrochemical performances of layered LiNi6Mn2Co2O2(NCM622). The spherical morphologies, contributing to higher specific capacity of NCM622, ascribe to the same precipitation rate of transition metal ions (Ni2+, Co2+, Mn2+) during co-precipitation. Hence, the effects of different amounts of ammonia in initial solution on the hydroxide equilibrium constant and properties of NCM622 were discussed. With the ammonia content of 70 mL, the spherical morphology with more perfect layered structure and higher discharge capacity are obtained. The necessity of ammonia content in initial solution are also demonstrated from electrochemical performances of NCM622, such as the initial discharge capacity of 199.8 mAh g−1at 0.1 C, the specific capacity of 150.0 mAh g−1after 100th cycles, and the capacity retention rate of 89.6% at 3 C. If other metal ions are anticipated to be chemically doped with NCM622, the hydroxide equilibrium constant and precipitation rate need to be considered.Keywords:lithium ion batteries;hydroxide co-precipitation method;NCM ternary precursor;electrochemical performance