Al3+ Doped Li(Ni-Ni0.9Co0.1)O2 Core-Shell Cathodes for Rapid Charging and Dramatic Cycle Performance

Abstract

Nickel-rich layered Li(Ni-Ni0.9Co0.1)O2 is a promising cathode material due to its high specific capacity. However, commercial application of this material is impeded by its rapid capacity degradation associated with structural instability. In this work, 0.01mol Al3+ Doped Li(Ni-Ni0.9Co0.1)O2 cathode material is prepared by heat treatment of a mixture of stoichiometric amounts of nano-sized Al(OH)3 powders, co-precipitated (Ni-Ni0.9Co0.1)(OH)2 precursors, and LiOH·H2O. The results show that Al3+ doping significantly improves the cycling properties of Li(Ni-Ni0.9Co0.1)O2 cathode material. Under a voltage range of 3–4.5 V, 0.02 mol% Al3+ doped Li(Ni-Ni0.9Co0.1)O2 cathode material shows an initial discharge capacity of 210 mAh/g at 0.1C, with a capacity retention of 97% for subsequent 100 cycles at 1C at room temperature. In contrast, bare Li(Ni-Ni0.9Co0.1)O2 shows a capacity retention of only ~62.8% under the same conditions, with an initial specific discharge capacity of 220 mAh/g. The improvement in cycling performance is attributed to stabilization of the layered structure by Al3+ , mitigated migration of Ni2+ to the Li layer, improved lithium diffusion kinetics and reduced lattice expansion/shrinkage during cycling. Stabilization of the layered structure by Al3+ doping is further reflected by the observation of fewer cracks in cathode electrodes after prolonged cycling.