P-046

Paul Conrad Hoffmann

paul.hoffmann@uni-ulm.de

Thomas Diemant, Hagar K. Hassan, Timo Jacob

Ulm University, Germany

Is Mg3AsN Antiperovskite a Promising Mg-Ion Conductor?

Despite magnesium's lower specific capacity and redox potential than lithium, its superior safety makes it a strong candidate for safety/critical applications. However, challenges such as slow Mg²⁺ diffusion and poor reversibility impede the commercialization of rechargeable magnesium-ion batteries (RMBs). Addressing these challenges requires designing new electrodes and electrolytes distinct from lithium-based technology. Solid-state electrolytes (SEs) promise enhanced safety and performance compared to liquid counterparts enabling a high degree of tunability and innovative electrochemical designs.

Antiperovskites (APs), with their inverted anion-cation structure (X₃BA vs. conventional ABX₃ in perovskites), are emerging as promising SEs for monovalent ion batteries due to their high ionic conductivity and structural flexibility.[1] In the pursuit of a suitable AP for multivalent ion batteries, Kim and Siegel [2] suggested Mg₃AsN AP as a fast Mg-ion conductor, experimental validation remains limited. Here, we report the first experimental evaluation of the ionic and electronic transport properties of Mg₃AsN and methods for its electronic properties modification. 

Our findings revealed that the pristine Mg3AsN exhibited mixed conductivity with ionic and electronic conductivities of  5.5 × 10⁻⁴ S·cm⁻¹, and 4.89 × 10⁻⁸ S·cm⁻¹, respectively, at 100 °C. Thermal treatment enhanced its ionic transport properties, raising tion from 0.07 to 0.615 at 0.5 V. Introducing Mg2+ ion vacancies, Mg2.75AsN, raised the tion to 0.6 at 0.5 V, maintaining the electronic conductivity at 5 × 10⁻⁸ S·cm⁻¹. In contrast, the addition of excess Mg₃N₂ notably reduced electronic conductivity to 2.15 × 10⁻⁹ S·cm⁻¹, highlighting its influence on charge transport behavior. These findings demonstrate the ability to tune Mg₃AsN’s properties through structural modifications, paving the way for further investigation and optimization.

References:

[1] Gao, L., Zhang, X., Zhu, J. et al. , Nat Commun 14, 6807 (2023). https://doi.org/10.1038/s41467-023-42385-1

[2] K. Kim and D. J. Siegel, Chemistry of Materials, vol. 33, no. 6, pp. 2187–2197, Mar. 2021, doi: 10.1021/acs.chemmater.1c00096.