New Class of Ni-Rich Cathode Materials Li[NixCoyB1−x−y]O_2 for Next Lithium Batteries

摘要

A new class of layered cathodes, Li[NixCoyB1-x-y]O-2 (NCB), is synthesized. The proposed NCB cathodes have a unique microstructure in which elongated primary particles are tightly packed into spherical secondary particles. The cathodes also exhibit a strong crystallographic texture in which the a-b layer planes are aligned along the radial direction, facilitating Li migration. The microstructure, which effectively suppresses the formation of microcracks, improves the cycling stability of the NCB cathodes. The NCB cathode with 1.5 mol% B delivers a discharge capacity of 234 mAh g(-1) at 0.1 C and retains 91.2% of its initial capacity after 100 cycles (compared to values of 229 mAh g(-1) at 0.1 C and 78.8% for pristine Li[Ni0.9Co0.1]O-2). This study shows the importance of controlling the microstructure to obtain the required cycling stability, especially for Ni-rich layered cathodes, where the main cause of capacity fading is related to mechanical strain in their charged state.