Pushing the Energy-Lifetime Frontier of Li-Ion Batteries: Study of Ni-Rich, Co-Free NMAW Cathode Material

Abstract Dopants and coatings have been widely used to improve the performance of Ni-rich positive electrode active materials. Previous studies have aimed to elucidate the mechanism by which Al and W improve lithium metal oxides, providing valuable insight on the design of enhanced electrode materials for Li-ion batteries. In this work, Al and W are compared as individual dopants as well as co-dopants in order to design an optimal Ni-rich, Co-free material. This involved studying the effect of synthesis temperature in the presence of Al and/or W as well as the effect that these metals have on the morphology of the resultant polycrystalline materials. In addition, structural analysis by X-ray diffraction, electrochemical analysis, and characterization of the mechanical strength of the materials were also conducted. The change in performance with the addition of Al and W depends greatly on particle size and chemical composition. Small sized Ni-rich polycrystalline particles (Ni content of 94%) with low contents of Al (3%) and W (1%) showed the greatest enhancement in energy density with good cycle life.