Prevention of the Micro Cracks Generation in LiNiCoAlO2 Cathode by the Restriction of ΔDOD

Abstract

Lithium Nickel-Cobalt-Aluminum oxide cathode material taking out from lithium-ion cell after restricted DOD (Depth of Discharge) range cycle was analyzed by X-ray diffraction (XRD), cross section scanning electron microscope (SEM), transmission electron microscope (TEM) and scanning transmission electron energy-loss spectroscopy (STEM-EELS). Many of the micro cracks were observed in the cathode particles after 0-100% DOD range cycle. On the other hand, that was little confirmed regardless of the operated voltage area when cycled DOD range was restricted. After generation of the micro cracks, the crystal structure at the surface of primary particles which was faced on them was immediately changed to rock salt like structure. The cycle performance under the conditions of restriction of ΔDOD showed superior results of 3000 cycles even at 50°.