High Performance of Porous, Hierarchically Structured P2‐Na_0.6Al_{0.11 − x}Ni_{0.22 − y}Fe_{x + y}Mn_0.66O₂ Cathode Materials

Abstract

Sodium‐ion‐batteries (SIB) are a low‐cost alternative to currently used lithium‐ion batteries (LIB) but suffer from poor cycling stability. Spray drying provides porous, hierarchically structured particles of cathode active material (CAM) in large amounts, suitable for up‐scaling. Changing the chemical composition of the Na0.6Al0.11 − xNi0.22 − yFex + yMn0.66O2 layered oxides under identical synthesis conditions lead to differences in particle morphology, conductivities, sodium vacancy ordering, and phase transition, therefore influencing the electrochemical performance via several mechanisms. Here, a broad overview on these changes for samples with variable nickel and iron content is presented. With increasing iron content, the particle porosity is reduced and lower initial capacity is received for most cycling windows. Substituting half of the original Ni amount with Fe still leads to high capacities and improved cycling stability. The influence of Al as electrochemically inactive element becomes visible in stabilized cycling stability as well.