LiNi0.8Co0.15Al0.05O2 cathode materials prepared by TiO2 nanoparticle coatings on Ni0.8Co0.15Al0.05(OH)(2) Precursors

Abstract

Synthesis, electrochemical, and structural properties of LiNi0.8Co0.15Al0.05O2 cathodes prepared by TiO2 nanoparticles coating on a Ni0.8Co0.15Al0.05(OH)(2) precursor have been investigated by the variation of coating concentration and annealing temperature. TiO2-coated cathodes showed that Ti elements were distributed throughout the particles. Among the coated cathodes, the 0.6 wt% TiO2-coated cathode prepared by annealing at 750 degrees C for 20 h exhibited the highest reversible capacity of 176 mAh g(-1) and capacity retention of 92% after 40 cycles at a rate of 1C (=190 mA g(-1)). On the other hand, an uncoated cathode showed a reversible first discharge capacity of 186 mAh g(-1) and the same capacity retention value to the TiO2-coated sample at a 1C rate. However, under a 1C rate cycling at 60 degrees C for 30 cycles, the uncoated sample showed a reversible capacity of 40 mAh g(-1), while a TiO2-coated one showed 71 mAh g(-1). This significant improvement of the coated sample was due to the formation of a possible solid solution between TiO2 and LiNi0.8Co0.15Al0.05O2. This effect was more evident upon annealing the charged sample while increasing the annealing temperature, and at 400 degrees C. the coated one showed a more suppressed formation of the NiO phase from the spinel LiNi2O4 phase than the uncoated sample.