Sc improves lithium ion cathode material cycle performanceConclusion
NMC 811 and Sc-doped NMC cathode precursors have been successfully synthesized using the co-precipitation method. The synthesized NMC 811 and Sc-doped NMC were identified to have a hexagonal structure. Adding an Sc dopant increases the crystallite size and the distance between the crystal layers. Moreover, Sc-doped NMC has coarser grains than un-doped NMC 811. The initial discharge capacity of the Sc-doped NMC cell was lower than that of the un-doped NMC. The NMC 811 sample shows an initial discharge capacity of 147.56 mAh/g with an initial efficiency of 87.048 %. With the addition of Sc dopant of 2.5 %, 5 % Sc, and 7.5 % mole of Sc from total mol of Ni + Mn + Co + Sc, the discharge capacities of 143.66 mAh/g, 136.23 mAh/g, and 125.25 mAh/g were respectively obtained, with respective efficiencies of 77.02 %, 71.69 %, and 84.47 %. Sc doping at NMC cells increases the cell duty cycle and retention capacity. The NMC-7.5%Sc demonstrated the best capacity retention of 87.54 % after 100 cycles. Based on the EIS measurements after 100 cycles of charge-discharge test, the best calculated ionic conductivity of 4.61 × 10−7 S/cm and lithium-ion diffusion coefficient of 3.92 × 10−10 cm2/s was demonstrated by NMC-7.5 % Sc cell. The research result demonstrated that doping Sc to the nickel-rich NMC cathode is an attractive approach to increase the NMC 811 battery duty cycle and retention capacity.
https://www.sciencedirect.com/science/article/pii/S0254058423014347