Performance of Mg stabilised Na-β’’-alumina solid electrolytes prepared by direct ink writing

Mg-stabilised Na-β’’-alumina solid electrolyte (Mg-BASE) for Na-ion batteries was synthesised and fabricated into 3D structures via direct ink writing (DIW), an extrusion-based additive manufacturing process. To produce a water-based ink with optimum viscoelastic properties and supreme printing quality, a comprehensive investigation of ink formulation and printing parameters was conducted. The sintered 3D structures of Mg-BASE, fabricated via direct ink writing, achieved relative density of 98.0 ± 1.1 % with β’’ phase fraction of 99.7 wt% whilst bulk ionic conductivity of 0.081 S⋅cm −1 at 350 °C was obtained. XRD results indicated that Mg-BASE fabricated via DIW may have different c-axis orientation than conventional dry-pressed pellets, leading to the improved bulk ionic conductivity. • Mg-stabilised Na-β’‘-alumina solid electrolyte was fabricated into 3D structures via DIW using a sustainable aqueous ink. • High solids loading inks (67 wt%/46 vol%) were developed leading to highly densified (98%±1.1) solid electrolytes. • Na-β’‘-alumina fabricated by DIW exhibits 22.7 % higher bulk ionic conductivity than conventional dry-pressed electrolytes.