Nitrogen Plasma Enhanced Low Temperature Atomic Layer Deposition of Magnesium Phosphorus Oxynitride (MgPON) Solid‐State Electrolytes

Abstract Solid‐state batteries (SSBs) that use solid electrolytes instead of flammable liquid electrolytes have the potential to generate higher specific capacity and offer better safety. Magnesium (Mg) based SSBs with Mg metal anodes are considered to be one of the most promising energy storage candidates, because it gives high theoretical volumetric capacities of 3830 mAh cm−3. Here, we demonstrate an atomic layer deposition (ALD) process with a double nitrogen plasma process that successfully produces nitrogen‐incorporated magnesium phosphorus oxynitride (MgPON) solid‐state electrolyte (SSE) thin films at a low deposition temperature of 125 °C. The ALD MgPON SSEs exhibit an ionic conductivity of 0.36 and 1.2 μS cm−1 at 450 and 500 °C, respectively. The proposed ALD strategy shows the ability of conformal deposition nitrogen‐doped SSEs on pattered substrates and is attractive for using nitride ion‐conducing films as protective or wetting interlayers in solid‐state Mg and Li batteries.