Multi-geometric carbon encapsulated SnP₃ composite for superior lithium/potassium ion batteries

Tin phosphide has gained extensive attention as a prospective anode for lithium/potassium ion batteries because of its high theoretical capacity. Nevertheless, the fast capacity fading, which is induced by the huge volume expansion and poor electrical conductivity during cycling, severely restricts its practical applications. In this work, a SnP₃-CNTs/KB composite with a SnP₃ content as high as 90 wt% was successfully synthesized by a two-step ball milling method. SnP₃ nanoparticles were tightly encapsulated in multi-geometric composite carbon layers to efficiently relieve the volume changes and enhance conductivity. Specifically, the resulting SnP₃-CNTs/KB anode showed a specific capacity up to 998.6 mA h g^-1 after 100 cycles at 50 mA g^-1 and 810.4 mA h g^-1 after 500 cycles at 1000 mA g^-1 for lithium ion batteries. For potassium ion batteries, a high reversible capacity of 200.2 mA h g^-1 was achieved after 200 cycles at 1000 mA g^-1. This work affords a new insight for exploring excellent support structures of tin phosphide-based anodes.