A Self-Propagating High Temperature Synthesis Method To Preare Lithium Cobalt Oxides As Cathode Materials For Lithium Ion Battery

There is an increasing interesting in lithium ion batteries, consisting ofintercalation compounds for cathode, in accordance with the development ofportable electronic equipment, and as a power supply for future vehicles andload leveling systems. Among the known, LiCoO₂ is currently used as a cathodematerial for commercial lithium ion batteries. LiCoO₂ is commonly prepared bysolid-state reaction, which requires high-temperature sintering for a long timeand results in inhomogeneity, irregular morphology, and broad particle-sizedistribution of powder.To overcome these disadvantages, a modified Self-Propagating HighTemperature Synthesis (SHS) method using urea and carbon instead of the metalas fuel has been employed for the preparation of LiCoO₂. The objectives of thiswork are: (1) to prepare LiCoO₂ powders by modified SHS, (2) to examine theeffects of synthesis conditions on the formation of LiCoO₂ particles and itselectrochemical properties by XRD, SEM and electrochemical method.The optimum conditions for synthesizing LiCoO₂ by urea SHS as follows:urea:Co is 1:1(mole ratio), Li:Co is 1.05:1(mole ratio), burning and annealing temperature is 800℃, and annealing time is 2h. The mole ratio of carbon and Cois 0.5:1 in the carbon SHS. Other conditions were similar with the urea SHS.The electrochemical performance results show that LiCoO₂ prepared byurea SHS and carbon SHS had good capacity and cycle performance. TheLiCoO₂ from urea SHS delivered initial discharge capacity of is 155mAh/g, andthat of carbon SHS was 148mAh/g. The capacity retention rate was 95% and97% after 10th cycles at 75mA/g, respectively.Compared with the traditional synthesis method, LiCoO₂ can be preparedby the self-propagating high temperature synthesis at the shorter time. Theresearch provided here can be considered as the base for optimizing themodified SHS conditions to prepare high performance LiCoO₂.