A Low-Cost Durable Na-FeCl_2 Battery with Ultrahigh Rate Capability

摘要

Na-based batteries have long been regarded as an inexpensive, sustainable candidate for large-scale stationary energy storage applications. Unfortunately, the market penetration of conventional Na-NiCl2 batteries is approaching its limit for several reasons, including limited rate capability and high Ni cost. Herein, a Na-FeCl2 battery operating at 190 degrees C is reported that allows a capacity output of 116 mAh g(-1) at an extremely high current density of 33.3 mA cm(-2) (approximate to 0.6C). The superior rate performance is rooted in the intrinsically fast kinetics of the Fe/Fe2+ redox reaction. Furthermore, it is demonstrated that a small amount of Ni additive (10 mol%) effectively mitigates capacity fading of the Fe/NaCl cathode caused by Fe particle pulverization during long-term cycling. The modified Fe/Ni cathode exhibits excellent cycling stability, maintaining a discharge energy density of over 295 Wh kg(-1) for 200 cycles at 10 mA cm(-2) (approximate to C/5).