LiNiO2 (LNO) is one of the most assuring substitutes to LiCoO2 in Li ion batteries (LIBs). Research is underway to improve the cycle life of LNO for its commercial use. This investigation involves the doping of Molybdenum (Mo), Niobium (Nb) and Zirconium (Zr) in lithium nickel oxide (LNO), marked difference in primary particle size morphology was observed. Simulations demonstrate that low level of doping can decline undesirable cation ordering [1-2].
X-Ray studies proved successful doping of Zr, Nb and Mo without displaying any additional peaks. A small addition (1 mol.%) of Zr, Nb and Mo during the calcination stage is seen to inhibit the growth of primary particles. Both Mo and Zr doped compositions delivered comparable capacity to pristine LNO from cycle 1, with 92% retention over 20 cycles. This improved cycling stability is due to change in particle morphology and changes in the crystal lattice due to doping.
Zr, Nb and Mo –1 mol. % LNO compositions delivered charge capacity (230, 200, 224 and 220) mAh/g respectively after cycle 1 @ C/20. Interestingly, the coulombic efficiency appears to be improved for the doped samples after the 3rd cycle.
Little difference in the electrochemical performance is seen between the Nb-1% composition.
Capacity retention is greater for the doped LNO compositions.
Sharp peaks are observed in the dQ/dV plot as expected. However, the polarization of charge/discharge peaks for the H2-H3 transition at high voltage appears to be slightly reduced for the Zr, Nb and Mo doped compositions.
This may indicate that TM doping can mitigate the influence of the volume change induced by the H2-H3 transition at high voltage, although further investigation is required.
Conclusion: Changes are observed in structure, morphology and electrochemical performance because of doping. Doping has improved the discharge capacity retention after 200 cycles for Zr-1% doped LNO.