Synthesis And Modification Of LiNi 0.8 Co 0.15 Al 0.05 O 2 Cathode Material For Lithium Ion Battery

Ni-rich LiNi1-xMxO2(1-x>0.6;M = Co,Mn,Al,etc.)material has been expected to be the most promising alternative to the dominant cathode material LiCoO2 for lithium ion batteries because of its similar layered structure to LiCoO2 and higher reversible capacity(>190 mAh/g).LiNi0.8Co0.15Al0.05O2(NCA)has specially been considered as an appealing cathode material among other Ni-rich candidates in terms of its improved stability and electrochemical performance as well as environmental friendliness caused by Co and Al cosubstitution in LiNiO2.Unfortunately,the use of NCA cathodes in practical lithium-ion cells has generally been plagued by several major drawbacks such as severe capacity fading during charge-discharge cycles and thermal run-away arising from structural instability caused by Li/Ni cation mixing.Ni0.8Co0.15Al0.05(OH)2 precursor was synthesized by coprecipitation method.The effects of ammonia,pH and aluminum source on the morphology of Ni0.8Co0.15Al0.05(OH)2 precursor were discussed.It was found that ammonia had an important effect on the growth of precipitation and the homogeneity of particles,and pH had a great influence on the tap density of the particles.The aluminum source has a large effect on the morphology of the particles.LiNi0.8Co0.15Al0.05O2 powders were synthesized by mixing LiOH·H2O and the co-precipitated hydroxide at different calcination conditions.The results imply that the temperature to synthesized purity LiNi0.8Co0.15Al0.05O2 phase no lower than 700 ?,and samples prepared 750 ? is the best among all the samples.Na+ doped samples of Li1-xNaxNi0.8Co0.15Al0.05O2 were prepared at 750? by co-precipitation method.The structure,morphology and electrochemical performance of Na+ doped samples were investigated.The results show that the samples become more stable and better to form layered structure with Na+ in lithium site,furthermore,doped samples seems have a better electrochemical performance than untreated samples.