Enhanced Cycling Life of a Three Dimensional LiCoO2 Sintered Electrode for Li-Ion Batteries

Abstract

The exploding growth of the portable electronic devices requires a high energy density battery. To meet this demand, the energy density of the conventional LIB is insufficient. The active material density in the conventional LIB electrode is limited to an amount of 3.8g / cc because the conducting agent and the binder are included in a considerable amount ( > 3%). Various studies are being conducted to improve energy density. Among them, research for removing conductive materials and binders from the cathode and to maximize electrode density through sintering is one of the most important candidates. This is because the density can be improved to 4.5 g / cc through sintering process. That way, energy density can be increased by 20%. In addition, unlike the existing jellyroll type, using the sintered LiCoO2 electrode, various shapes and thicknesses of batteries can be produced. However, there is a problem that the movement of lithium ion in the cathode should be made within the solid state active material. Since ions are much slower in solid state than in the liquid state, the sintered cathode has a fatal disadvantage that it is vulnerable to high rate characteristics. In addition, cracking in the grain boundary in the layered cathode deteriorates the cycle life performance.In this research, we propose a method to improve a cycle life of Li ion batteries with three dimensional LiCoO2 sintered electrode. We suggest the mechanism for the internal crack propagation of the sintered cathode, and suggest to mitigate the crack propagation by a conductive bonding agent. The conductive bonding agent formed a conductive path inside the cathode so that electrons could move even in a crack. The cathode showed a 130% improved cycle performance with a high current density of 3.0 mA/cm2. The study was the first to prove the performance of cycle life of the 3D sintered cathode in fullcell configuration, and it is meaningful in that it mitigates the deterioration caused by internal crack propagation, which is a problem that must be solved in order to apply the sintered cathode to the industrial level. In the commercialization of smaller, higher capacity and longer cycle life batteries using sintered cathodes, we hope the concepts proposed in this study will help.