Studies on LiNi 0.7Al 0.3− xCo xO 2 solid solutions as alternative cathode materials for lithium batteries

Abstract

A series of phase-pure Co- and Al-substituted lithium nickel oxide solid solutions of the composition LiNi 0.7Al 0.3− x Co x O 2 with x=0.0, 0.1, 0.15, 0.2, and 0.3, has been synthesized by adopting urea-assisted combustion (UAC) route. The structure and the physico-electrochemical features of the doped materials have been evaluated through PXRD, FTIR, SEM, CV, and charge/discharge studies. The stabilization of Ni in the +3 state and the existence of enhanced 2D-layered structure without any cation mixing have been substantiated from XRD. The results of the XRD and FTIR studies have established the complete mixing of Al and Co with Ni, especially at the various levels and the combinations of the dopants attempted in the present study. The enhanced electrochemical performance of LiNi 0.7Al 0.3− x Co x O 2 may be attributed to the “synergetic effect” resulting from the presence of both Al 3+ and Co 3+ dopants in the LiNiO 2 matrix. From CV studies, it was understood that the addition of 10% Co is effective in suppressing the phase transformation during Li + intercalation process that leads to better electrochemical properties. The effect and the extent of substitution of Ni with Al and Co on the structural and electrochemical performance of LiNi 0.7Al 0.3− x Co x O 2 are discussed elaborately in this communication.