Simple co-precipitation synthesis of high-voltage spinel cathodes with different Ni/Mn ratios for lithium-ion batteries

The high-voltage spinel is a promising cathode material in next generation of lithium-ion batteries. Samples LiNi0.5 − xMn1.5 + xO4 (x = 0, 0.05, 0.1) are synthesized by a simple co-precipitation method, in which pH value and temperature conditions do not need control. In the simple co-precipitation method, NaHCO3 solution is poured into transition metal solution to produce precursor. Ni and Mn are distributed uniformly in the products. The as-prepared samples are composed of ~ 200 nm primary particles. Samples LiNi0.5 − xMn1.5 + xO4 (x = 0, 0.05, 0.1) are also tested to study the effects of different Ni/Mn ratios. Sample LiNi0.5Mn1.5O4 delivers discharge capacities of 130 mAh g−1 at 0.2 C. The decreasing of Ni/Mn ratio in samples reduces specific capacity. With the decreasing of Ni/Mn ratios in spinel, amount of Mn3+ are increased. Attributed to its high Mn3+ contents, sample LiNi0.4Mn1.6O4 delivers the highest discharge capacity of 106 mAh g−1 at a large current density of 15 C, keeping 84.5% of that at 0.2 C rate. With the increasing of Ni/Mn ratios in spinel, cycling performance is improved. Sample LiNi0.5Mn1.5O4 shows the best cycling stability, keeping 94.4% and 90.4% of the highest discharge capacities after 500 cycles at 1 C and 1000 cycles at 5 C.