Controllable preparation of alumina nanorods with improved solid electrolyte electrochemical performance

Abstract Alumina powders have been widely used in lithium-ion batteries such as separator coating, electrode surface modification and electrolyte fillers. Rod-like alumina with its special aspect ratio is expected to open up a new application direction. In this work, alumina nanorods were prepared by a facile hydrothermal method. The aspect ratio and morphology of alumina nanorods were optimized by adjusting the hydrothermal temperature, hydrothermal synthesis time, volume ratio, directing agent, and sintering temperature. γ-Al2O3 nanorods with a diameter of 200–300 nm and a mean length of 5 μm and α-Al2O3 with a diameter of 100–200 nm and mean length of 5 μm were obtained by calcining the alumina precursor (AACH) at 800 °C and 1200 °C, respectively. The prepared alumina nanorods were added into polymer solid electrolyte, which promoted the dissociation of the lithium salt and stabilized the propylene polycarbonate (PPC) polymer, resulting in an improved potential window (4.5 V) and ionic conductivity (3.7 × 10−4 S/cm) of the PPC-based polymer solid electrolyte (SE). An NCM622/SE/Li solid-state battery showed enhanced electrochemical performance at ambient temperature with an initial discharge capacity of 188.5 mAh/g and a retention capacity of 158.1 mAh/g after 200 cycles at a current density of 0.5 C. These alumina nanorods have potential to be widely used in high-performance solid electrolytes.