Ultrafine Sn4P3 nanocrystals from chloride reduction on mechanically activated Na surface for sodium/lithium ion batteries

Nanostructured metal phosphides are very attractive materials in energy storage and conversion, but their applications are severely limited by complicated preparation steps, harsh conditions and large excess of highly toxic phosphorus source. Here we develop a highly efficient one-step method to synthesize Sn 4 P 3 nanostructure based on simultaneous reduction of SnCl4 and PCl 3 on mechanically activated Na surface and in situ phosphorization. The low-toxic PCl 3 displays a very high phosphorizing efficiency (100%). Furthermore, this simple method is powerful to control phosphide size. Ultrafine Sn 4 P 3 nanocrystals (< 5 nm) supported on carbon sheets (Sn 4 P 3 /C) are obtained, which is due to the unique bottom-up surface-limited reaction. As the anode material for sodium/lithium ion batteries (SIBs/LIBs), the Sn 4 P 3 /C shows profound sodiation/lithiation extents, good phase-conversion reversibility, excellent rate performance and long cycling stability, retaining high capacities of 420 mAh/g for SIBs and 760 mAh/g for LIBs even after 400 cycles at 1.0 A/g. Combining simple and efficient preparation, low-toxic and high-efficiency phosphorus source and good control of nanosize, this method is very promising for low-cost and scalable preparation of high-performance Sn 4 P 3 anode.