High Energy Density Na-Ion Battery Technology

Abstract

High energy density sodium-ion (Na-ion) batteries are now close to successful commercialization. These energy storage devices offer some significant advantages over their lithium-ion counterparts, such as lower material costs, improved safety characteristics and superior transportation properties [1,2]. In this study we demonstrate the electrochemical performance characteristics of full Na-ion cells constructed using a proprietary layered oxide cathode NaaNi(1-x-y-z)MnxMgyTizO2 and a hard carbon anode material [3]. Figure 1 depicts the voltage profile for a typical Faradion Na-ion cell. The cathode material delivers a reversible specific capacity of over 146 mAh/g and the cell generates an average discharge cell voltage of around 3.2 V. The projected specific energy for this battery system is 140-150 Wh/kg. The cell cycles with low polarization and with excellent columbic and (round-trip) energy efficiency. Figure 2 denotes a typical cycle life plot (100 % DOD) for a representative Na-ion cell. Following 170 cycles the discharge capacity fade is less than 1%. Simple linear extrapolation indicates that this cell should cycle 1000 cycles while maintaining well over 90% of its original discharge capacity. To demonstrate the commercial viability of Na-ion batteries, Faradion has scaled-up this cell chemistry to the 3 Ah (9 Wh) prismatic pouch cell level. These cells were fabricated using traditional Li-ion manufacturing methods. Multiple prototype cells have been incorporated successfully into E-Bike (>400 Wh) and E-Scooter (>750 Wh) demonstrator packs [4,5]. Further performance and safety characteristics of the Na-ion cells will be provided during the presentation.