Surface synergistic protections on red phosphorus anode material by PEDOT coating and electrolyte strategy in sodium ion batteries

Red phosphorus (RP) has attracted more attention as a promising sodium storage material due to its ultra-high theoretical capacity, suitable sodiation potential. However, the low intrinsic electrical conductivity and large volume change of pristine RP lead to high polarization and fast capacity fading during cycling. Herein, surface synergistic protections on red phosphorus composite is successfully proposed by conductive poly (3, 4-ethylenedioxythiophene) (PEDOT) coating and electrolyte strategy. Nanoscale RP is confined in porous carbon skeleton and the outside is packaged by PEDOT coating via in-situ polymerization. Porous carbon provides rich access pathways for rapid Na+ diffusion and empty spaces accommodate the volume expansion of RP; PEDOT coating isolates the direct contact between electrolyte and active materials to form a stable solid electrolyte interphase. In addition, the reformulated electrolyte with 3 wt% SbF3 additive can stabilize the electrode surface and thus enhance the electrochemical performance, especially cycling stability and rate capability (433 mAh g-1 at high current density of 10 A g-1).