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 flexible 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.