A comparative study of layered and spinel LiCo _0.85 Al _0.15 O ₂ cathode materials

Lithium cobalt aluminium oxide (LiCo 1-x Al x O 2 ) has broad application prospects, yet the study of its structure-performance relationship is still insufficient. Here, this study systematically compares the electrochemical performance and structure-performance relationship of layered LiCo 0.85 Al 0.15 O 2 (L-LCAO) and lithiated spinel LiCo 0.85 Al 0.15 O 2 (S-LCAO). L-LCAO, sintered at 950℃, is composed of micron-sized particles and shows a unit-cell-volume change rate of only 1.76%, with the two-phase reaction being significantly suppressed. In contrast, S-LCAO, sintered at 400℃, is composed of agglomerated nanoparticles, and exhibits a single-phase reaction with a unit-cell-volume change rate of only 0.60%. The small unit-cell-volume variations of L-LCAO and S-LCAO enable outstanding cycling stability, with capacity retentions of 94.8% and 90.2% after 50 cycles at 0.1C, respectively. L-LCAO delivers an initial discharge specific capacity of 133.3 mAh g -1 , higher than that of S-LCAO (106.4 mAh g -1 ). However, S-LCAO exhibits superior rate capability due to its faster Li + diffusivity rooted in three-dimensional Li + diffusion channels and its shorter Li + diffusion distances rooted in small primary particles. This study can provide important guide for the further development and optimization of energy storage materials.