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.

Development of plasma technology for the preparation and modification of energy storage materials

“…The incorporation of plasma into functional materials can lead to two distinct effects: physical effects and chemical effects. Physical effects encompass processes such as doping, [23][24][25] etching, [26][27][28][29] vacancy formation, [30][31][32] deposition, [33][34][35] and stripping, while chemical effects involve oxidation, nitridation, sulfidation, phosphatization, reduction, and polymerization. 15 Due to its high reactivity, plasma allows for the simultaneous occurrence of doping, etching, and generation of vacancies.…”

Li, Na, K, Mg, Zn, Al, and Ca Anode Interface Chemistries Developed by Solid‐State Electrolytes

“…Table 1 provides the state‐of‐the‐art multivalent SEs and their properties. [ 10–12,32,39,102,112–232 ]…”

“…Magnesium phosphorus oxynitride (MgPON) SEs are also reported by using ALD with double nitrogen plasma processes at a low deposition temperature of 125 °C. [ 229 ] MgPON displays amorphous nature without grain boundaries and σ Mg 2+ ≈0.58 nS cm −1 at 300 °C, 1.1 times larger than magnesium phosphate (MgPO). For 400 and 500 °C, it shows 6.2 and 7.5 times larger σ Mg 2+ .…”

“…[ 508–511 ] Su et al. [ 229 ] proposes the uniform and conformal magnesium phosphorus oxynitride (MgPON) thin films over Si substrates (thickness ≈62 nm) by using ALD. MgPON SEs σ Mg 2+ is of 62 nS cm −1 , 0.36 µS cm −1 , and 1.2 µS cm −1 at 400, 450, and 500 °C, respectively.…”

“…Several Mgalloy-based anodes, such as 𝛽-Mg 3 -Bi 2 , Mg 2 -Ga 5 , Mg 2 Sn, Mg 2 -Sb, and MgF 2 -Mg, are also reported to increase the compatibility of Mg-alloys anodes. [508][509][510][511] Su et al [229] proposes the uniform and conformal magnesium phosphorus oxynitride (Mg-PON) thin films over Si substrates (thickness ≈62 nm) by using ALD. MgPON SEs 𝜎 Mg 2+ is of 62 nS cm −1 , 0.36 μS cm −1 , and 1.2 μS cm −1 at 400, 450, and 500 °C, respectively.…”