Phosphorus-rich tin phosphide-carbon nanotubes composite as a high-performance anode for potassium ion batteries

Tin phosphides , especially phosphorous-rich tin phosphides, have recently attracted increasing attention as promising anode materials for potassium ion batteries (PIBs) because of their high theoretical capacities and suitable operating voltages. However, large volume changes during potassiation/depotassiation processes severely limit their performances. Herein, SnP 3 /carbon nanotubes (SnP 3 /CNTs) composite was successfully prepared through a ball-milling technique and investigated as a novel anode material for PIBs. The SnP 3 /CNTs-20 composite electrode delivered a reversible capacity of 373 mAh g −1  at 200 mA g −1 after 100 cycles and exhibited excellent rate capabilities. After 150 cycles at 1000 mA g −1 , a high capacity of 190 mAh g −1 remained. The superior performances of SnP 3 /CNTs-20 composite electrode were ascribed to the critical roles of CNTs matrix in buffering volume expansion, boosting electrical conductivity , and avoiding over thick SEI film. Furthermore, the phase transformation and structural evolution of the SnP 3 /CNTs-20 composite were identified by exploiting ex-situ X-ray diffraction (XRD) and ex-situ scanning electron microscope (SEM), respectively. These results are expected to inspire the development of advanced tin phosphide based anode materials for PIBs.