Improvement of Initial Coulombic Efficiency of Co[sub 3]O[sub 4] by Ballmilling Using Ni as an Additive

Graphite has been widely used as the anode material of commercial Li-ion secondary batteries. With the growing demands of high-capacity secondary batteries, the low capacity of graphite has been looked upon as the limiting factor in wide applications and new anode materials with high capacity have been sought. Among many materials, showed the best anode performance. It has high capacity of about 700 mAh/g and good cycle life (93.4% of initial capacity is maintained after 100 cycles). However, because its irreversible capacity comes to about 30% of initial capacity, the initial coulombic efficiency needs improvement in order to commercialize as the anode material of Li secondary batteries. Because it was reported that is cycled through the formation and decomposition of a poor decomposition of at the first charge can be regarded as the cause of high initial irreversible capacity. Therefore, at first, addition of Ni to was selected as a method to decrease the initial irreversible capacity, but it didn't have any effect. The ballmilling method was known to be very effective, connecting original material with additive material. As a result of ballmilling with Ni, on which Ni is well dispersed was obtained, and as expected, its irreversible capacity was decreased from 30 to 20%.