A facile structure design of concentration-gradient LiNi0.80Co0.15Al0.05O2 cathode material for lithium-ion batteries via controlling the flow rate of Al solution

In this work, we have explored the design of a new concentration-gradient LiNi0.80Co0.15Al0.05O2 cathode material, which was successfully synthesized via sintering the mixture of core/shell precursor and LiOH·H2O in O2. The precursor Ni0.80Co0.15Al0.05(OH)2 was synthesized via co-precipitation by controlling the flow rate of the aluminum solution has a core of NimCo1-m(OH)2 (m = 0.88 or 0.92) and the outer-layer of Ni1.6-mCom-0.7Al0.10(OH)2. The results indicate that the lattice misfits between the core precursor and core/shell one is relatively small, which make NixCoyAl1-x-y(OH)2 uniformly and efficiently on NimCo1-m(OH)2 precursors by controlling the flow rate of the Al solution. The concentration of main elements of LiNi0.80Co0.15Al0.05O2 changes gradually from the center to the particle surface. The material displays a discharge capacity of 198.6 mAh g−1 (m = 0.88) and 187.8 mAh g−1 (m = 0.92) at 0.2C, which are lower than the homogeneous LiNi0.80Co0.15Al0.05O2 (NCA-H) with 205.8 mAh·g−1. In addition, it also shows excellent capacity retention of 70.3% and 78.9% at 1C after 200 cycles respectively, which are much better than NCA-H with 54.6%.