Study On The Li-Ni-Co-Mn-O Compound As Cathode Material For Lithium-Ion Battery And Its Application In Lithium-Ion Batteries

LIB is one of the most important way to solve the problem of energy sources. As an important part of LIB,the performance of cathode material will affect the performace of LIB.We will study the Li-Ni-Co-Mn-O compound,and assembled 18650 LIB to search its performance.We hope to find a way to get LIB with better performance.The main content of this thesis includes four parts: Preparation of layered LiNi_xCo_yMn_1-x-yO₂ with microemulsion and high temperature solid reaction, influence by Co,Mn content variety; studies on the factors of sinter process and improve it; the trial-assembling of 18650 Li-ion batteries for high-power with LiMn_0.4Co_0.2Ni_0.4O₂ as cathode materials, test its cycle, rate abilities and safety; preparation of layered LiNi_0.35Co_0.3-xCr_xMn_0.35O₂ and LiMn_0.5-xCr_2xNi_0.5-xO₂ with microemulsion and high temperature solid reaction, study the influence on the structure and electrochemical performance by Cr-doped.It is important to study on the influence of the performance of Li-Ni-Co-Mn-O compound with different Co, Mn content,ywhich could lead us to prepare Li-Ni-Co-Mn-O compounds with different applications. LiNi_xCo_yMn_1-x-yO₂ with standard layered structure and excellent electrochemical performance have been prepared by microemulsion and high temperature solid reaction. The structures and appearance of the layered materials have been characterized by XRD and SEM et. al. The materials with different properties may be prepared by changing the proportion of Ni, Mn and Co.The capacity and rate capability of materials can be improved by increasing the content of Co. The ratio of Mn can influence the charge voltage.We get excellent Li-Ni-Co-Mn-O compound though that studies, which have high tap density,low specific surface area and excellent electrochemical performance. We have successfully prepared the layered structure LiNi_0.35Co_0.3-xCr_xMn_0.35O₂ with various Cr contents by a co-precipitation method.The test results showed that Cr doped can improve the performance of Li-Ni-Co-Mn-O compound.