Synthesis And Modification Of Lithium Ion Battery LiNi_0.8Co_0.15Al_0.05O₂

Lithium-ion battery has been widely used in cameras,mobile phones,notebook computers and other portable devices.It has also been used as a power battery in electric vehicles.People have made increasingly higher demands on their energy density,cycle performance,rate performance,safety and service life.The highest energy density of today's LIBs is about 210Wh/kg and 650Wh/L,being less than the values of a quarter of oil,which seriously restricts the uses of LIBs in electric vehicles.As the market demand for high energy density in Li-ion battery to rise,the common LiFePO₄?LiMn₂O₄ and LiCoO₂ cathode materials face a serious challenge.Therefore,it is important for the researchers to study and apply the new cathode materials.High nickel cathode materials LiNi_1-x-yCo_xAl_yO₂ has gotten a lot of attention,the Li-Ni-Co-Al-O compound as cathode for Li-ion battery is studied.LiNi_1-x-yCo_xAl_yO₂material is considered to be a very promising cathode material of next-generation lithium-ion battery.As a new cathode material,Li Ni_0.8Co_0.15Al_0.05O₂ cathode material possesses advantage of its excellent electrochemical performance and low cost,and especially has great potential to apply in power Li-ion battery.Therefore,it is a hot spot as cathode material for Li-ion battery.However,this material also has its own defects,especially in the high temperature sintering.Ni²⁺is difficult to completely convert to Ni³⁺,that will cause cation mixing and affect the performance of the material.The LiNi_0.8Co_0.15Al_0.05O₂ cathode material for lithium-ion batteries was synthesized by spray drying method.The effects of the pre-sintering temperature and time,the calcination temperature and time,on the structure and performance of material were investigated in details.The optimum process condition for LiNi_0.8Co_0.15Al_0.05O₂ preparation is as followed:the optimum ratio of Li/?Ni+Co+Al?is 1.08:1,and the material pre-sintered at the temperature of 510?and then sintered at 800?for 10h.We employ of X-ray?XRD?and scanning electron microscopy?SEM?to characterize the morphology,and crystal structure of LiNi_0.8Co_0.15Al_0.05O₂ and then the electrochemical performances with using the material as cathode for Li-ion battery are studied.The results show that,the initial discharge specific capacity of as-obtained LiNi_0.8Co_0.15Al_0.05O₂ cathode material can reach 190.3mAh/g at 0.1C,and the capacity retention rate is 92.9%after 50 charge-discharge cycles.The Li Ni_0.8Co_0.15Al_0.05O₂ was modified with laboratory-made LPAN,the best LPAN doping amount was about 10%.At 0.1C,the LPAN modified LiNi_0.8Co_0.15Al_0.05O₂ cathode material showed that the initial discharge specific capacity was 182.2mAh/g,and remained the 98.8%of initial capacity after 50 cycles.The above results demonstrate that the Li⁺extraction/insertion efficiency in the material was improved,and most importantly the LPAN doping not only can stabilize the structure of the material but also can improve the cycle stability.