Redox‐Mediated Red‐Phosphorous Semi‐Liquid Anode Enabling Metal‐Free Rechargeable Na‐Seawater Batteries with High Energy Density

Sodium-seawater batteries (Na-SWB) are considered among the most promising electrochemical devices for large-scale energy storage and marine sector. In fact, by employing an open-structured cathode, they benefit from unlimited supply of sodium seawater. This means, that such systems is intrinsically limited capacity anode. order to increase Na-SWB, it therefore necessary introduce a high-capacity anode as, e.g., red phosphorus. However, due its large volume changes upon charge/discharge processes, obtaining thick electrodes areal extremely challenging. Herein, areal/absolute phosphorus increased semi-liquid electrode, which includes two redox mediators, i.e., sodium-biphenyl sodium-pyrene, as reducing oxidizing species exploitation full capacity. As result, in Na-SWB provides 15 mAh cm–2 static anode, showing great potential operation flow-mode when storing negative electrode tank.