High-rate cycling in 3D dual-doped NASICON architectures toward room-temperature sodium-metal-anode solid-state batteries

Abstract

Sodium metal-based solid-state batteries hold tremendous potential for next-generation batteries owing to low-cost earth-abundant sodium resources. However, fabricating thin free-standing solid electrolytes that could cycle sodium at high current densities has been a major challenge in developing room temperature solid-state sodium batteries. By developing high conducting Zn²⁺ and Mg²⁺ dual-doped Na₃Zr₂SiPO₁₂ (NASICON) solid electrolytes and fabricating a 3D porous-dense-porous architecture (with an ultrathin, 25 μm, dense separator) coated with a nanoscale ZnO layer, an extremely low anode interfacial resistance of 3.5 Ω cm² was realized. This enabled a record high critical current density of 40 mA cm⁻² at room temperature with no stack pressure and a cumulative sodium cycling capacity of 10.8 A h cm⁻² was achieved. Furthermore, pouch cells were assembled as a proof-of-concept with Na₃V₂(PO₄)₃ cathodes on dense-porous bilayer electrolytes with sodium metal anodes and cycled up to 2C rates at room temperature with no applied stack pressure.