| Lithium ion batteries are widely used to power portable electronic devices suchas cell phones and laptop computers due to their high energy density. However, thecurrently used layered LiCoO2cathode could deliver only50%of its theoreticalcapacity in practical lithium ion cells due to the chemical and structural instabilities atdeep charge with (1-x)<0.5in Li1-xCoO2. Also, cobalt is relatively expensive and toxic.These difficulties have generated enormous interest in alternative cathode hosts. Inthis case, people developed a series of positive electrode materials. Because of its highcapacity and lower cost, LiNi0.5Mn0.5O2with layered structure is expected to become anew material to replace LiCoO2.In this paper, We use sodium carbonate coprecipitation to prepare the material.We add ammonia as complexing agent. CSTR device is adopted as reactor. During thepreparation, PH value, initial concentration of individual component, add the amountof ammonia, presintering temperature, amount of lithium mixture, the last sinteringtemperature preparation conditions were optimized. Finally, We get the best conditionof the preparation which is PH=8.00±0.05, initial concentration of components is1mol/L, mole ratio of ammonia and metal is1:1, presintering temperature is550℃,mixed lithium excess5%, the sintering temperature is900℃.We test the electrochemical properties of LiNi0.5Mn0.5O2which is prepared underthe best conditions. The first discharge capacity is174mAh/g at0.1C rate. After50circulation, there is an attenuation of capacity from178.6mAh/g to148.2mAh/g,capacity remain82.98%at0.2C.After that, we also take the ratio performance test,cyclic voltammograms test, ac impedance test. The results show that, LiNi0.5Mn0.5O2prepared under optimized conditions has excellent electrochemical performance. |
