Ga-Doped Ultrahigh-Nickel Oxide Microspheres with Radially Aligned Primary Grains as a Cathode for Stable Cycling Li-Ion Batteries.

Abstract

Owing to the high energy density, ultrahigh-nickel (Ni > 0.9) layered oxides are used as promising cathode materials for next-generation Li-ion batteries. Unfortunately, the serious pulverization and rapid capacity fading during cycling limit the commercial viability of an ultrahigh-nickel oxide cathode. Herein, the introduction of Ga into LiNi0.96Co0.04O2 brings a radially aligned microstructural change of oxide microspheres during the lithiation of the Ni0.96Co0.04(OH)2 precursor. As expected, such radially aligned needle-like primary grains on microspheres have a positive influence to reduce the anisotropic volume change and suppress the formation of microcracks of Ga-induced Li(Ni0.96Co0.04)0.99Ga0.01O2 during cycling. Specifically, compared with irregular primary grains of LiNi0.96Co0.04O2, Ga-induced oxide presents a high initial discharge capacity of 227.9 mA h g-1 at 0.1C rate between 2.8 and 4.3 V. Especially, Ga-induced oxide delivers higher initial discharge capacities of 233.9 and 240.3 mA h g-1 with higher cutoff charge voltages of 4.4 and 4.5 V at 0.1C, respectively. Furthermore, a good capacity retention of 74.1% at 1 C rate is obtained after 300 cycles, which is almost 85% higher than that of the pristine sample, mainly due to the generation of microcracks of oxide microspheres during the long-term cycle. Therefore, the introduction of Ga into LiNi0.96Co0.04O2 is a feasible approach for improving the microstructure and cycling stability of the ultrahigh-Ni layered oxides.