Boosting the capacity of Mg-stabilized Na0.67Ni0.27Mg0.06Mn0.66O2 cathodes via particle size control in an emulsion-based synthesis route

Abstract

In this work, the production of ultra-high efficient Na_0.67Ni_0.27Mg_0.06Mn_0.66O₂ cathodes synthesized via an emulsion-based organic synthesis route, along with a comprehensive atomic-scale characterization using advanced electron microscopy techniques, is presented. It is demonstrated that increasing the ratio of the surfactant to hydrophobic and hydrophilic components in the emulsion leads to optimized particle size and a significantly more uniform particle size distribution. As a result Na_0.67Ni_0.27Mg_0.06Mn_0.66O₂ exhibits superior electrochemical performance, delivering an initial discharge capacity of 260 mA h g⁻¹ and maintaining a discharge capacity of 170 mA h g⁻¹ after 100 cycles, with 99% coulombic efficiency. This enhancement is attributed to the synergistic effect of Mg-induced structural stabilization and the optimization of particle size and distribution. These factors collectively facilitate the accommodation of strain induced by repeated charge–discharge cycles without substantial structural degradation while preserving efficient sodium de-intercalation pathways.