Infrared-assisted Synthesis of Lithium Nickel Cobalt Alumina Oxide Powders as Electrode Material for Lithium-ion Batteries

This study explores an efficient infrared (IR) heating technique to synthesize highly-crystalline LiNi0.8Co0.15Al0.05O2 (NCA) cathode materials for Li-ion batteries. One home-made IR induction reactor, equipped with medium-wave IR emitter array, is adopted to prepare the NCA powders at 700 °C for a calcination period of 1-5 h. Two kinds of preparation routes, ball milling and rheological-phase method, are used to prepare NCA precursors. The as-prepared NCA powders display well ordering of hexagonal two-dimensional layer structure with low degree of cation mixing under appropriate conditions: IR heating time (5 h) and rheological-phase method. The NCA cathode exhibits an improved discharge capacity, fast Li+ diffusion rate, high rate capability, and good cycling stability. This improved performance mainly originates from low cation mixing, low defect level, and homogeneous particle size of NCA crystals. The carbon-coated NCA cathode offers high capacities of ca. 213 and 115 mAh g−1 at 0.1 and 5C, respectively. Analyzed by the Randles-Sevcik plots, the diffusion coefficients in the NCA cathodes increase up to 1.73 × 10−8 and 5.82 × 10−9 cm2 s−1 for Li-extraction and Li-insertion, respectively. Accordingly, the IR heating route turns on a commercial feasibility to synthesize NCA cathode materials for Li-ion battery application.