Cu4SnP10 as a promising anode material for sodium ion batteries

High theoretical capacity of metal phosphides makes them promising candidates for anode application in sodium ion batteries. In this work, we report a ternary compound phosphide-copper tin phosphide (Cu4SnP10) nanowires for sodium ion battery anode applications. The introduction of Cu helps to stabilize a rather high P content in the compound (as compared to Sn4P3, for example), enabling a high capacity of 811 mA h g(-1) at a current density of 25 mA g(-1) for phase pure Cn(4)SnP(10) nanowire anode. Cu incorporation is also found to effectively alleviate Sn aggregation in the anode during charge/discharge cycles, which is known as a major contributor to the faded cycle performance of Sn-P compound. On the other hand, we show that possible volume expansion and instability of the solid electrolyte interface in the Cn(4)SnP(10) nanowire anode remain as problems causing cycle instability of the electrode. By forming composite with multiwall carbon nanotubes, we demonstrate significantly improved cycle performance of the composite anode, which delivers a stable capacity of 512 mA h g(-1) after 100th cycle at a current density of 100 mA g(-1). At higher current density of 1 A g(-1), the capacity of the composite electrode retains at 412 mA h g(-1), showing its good rate performance.