Phosphorus-Based Two-Dimensional Anode Composites Enabling High Rate Capability and Long Life for Sodium Ion Batteries

Over the past decade, sodium ion batteries (SIBs) as a highly promising candidate for alternative battery technologies beyond Li-ion batteries (LIBs), have raised much attention for grid-level applications considering the sustainability of SIBs. However, compared with the multitudinous choices of anode materials for LIBs, their sodium counterparts are relative rare, which makes the electrochemical reactions in SIBs more difficult. In this work, we have investigated GeP3 with two-step protection as an anode material for SIBs. Through involving conductive carbon and graphene nano-sheets , GeP3/C@rGO possesses high electrical conductivity (5.89*10−1 S·cm−1 ) and high specific area (167.85 m2 g−1). Severing as a novel anode for SIBs, GeP3/C@rGO delivers an unprecedented reversible capacity of 800 mAh g−1 with repeating 400 cycles at 0.2 A g−1. Furthermore, the two-step protection sample (i.e., GeP3/C@rGO) could maintain a high discharge capacity of 473 mAh g−1 even at a high current density of 5 A g−1, which is higher than those of both pure GeP3 and one-step protection samples (i.e., GeP3/C, GeP3@rGO). Ex-situ XRD and XPS tests demonstrate that GeP3/C@rGO exhibits the highest reaction activation and highest composition stabilization to resists the damages from huge volume change and electrolyte corrosion with co-contribution of both conductive carbon and graphene nano-sheets components. All these properties suggest GeP3/C@rGO could sever as a promising anode material for SIBs, and the strategy of two-step protection is meaningful for other alloying-type anodes in the next-generation energy storage applications.