Application of nano Al_2O_3 particles as precipitate nucleus for preparation of high rate nickel-rich cathode materials

摘要

Nickel-rich layered oxide LiNi1-x-yCoxAlyO2 (x + y < 0.4) cathodes are regarded as the most promising candidate cathodes for lithium ion batteries due to their high energy density, high work voltage and low cost. These cathodes are extensively used in electric vehicles and hybrid electric vehicles. Generally, coprecipitation methods are frequently employed for preparing nickel-rich cathodes, but the coprecipitation of Ni2+, Co2+ and Al3+ is very complicated and uncontrollable because the solubility product constants of Ni(OH)(2), Co(OH)(2) and Al(OH)(3) are entirely different. This paper reports a modified coprecipitation method for the preparation of LiNi0.75Co0.15Al0.10O2, in which nano Al2O3 particles are employed as precipitate nucleus for the first time. Additionally, to magnify the difference between the different synthesis methods, a fluctuating pH environment is intentionally employed for the solution during the coprecipitation. Unlike the conventional method, the modified method successfully avoids the stringent demands for pH value during the synthesis, and the as-obtained LiNi0.75Co0.15Al0.10O2 cathode exhibits an excellent rate capability of 172.2 mAh g(-1) at a rate of 10 C. Even more remarkably, the LiNi0.75Co0.15Al0.10O2 cathode presents significantly improved thermal/structural stability and electrochemical performance at high temperature, indicating its great potential for use as a commercial lithium ion battery cathode in electric vehicles and hybrid electric vehicles.