Cobalt phosphide (Co₂P) encapsulated in nitrogen-rich hollow carbon nanocages with fast rate potassium ion storage

We synthesized Co2P nanoparticle encapsulated N-doped carbon nanocages through one-step carbonization-phosphidation of ZIF-67. As potassium ion battery (KIB, PIB) anodes, the Co2P@NCCs display state-of-the-art electrochemical performance, including the most favorable fast charge characteristics reported. The single-nanometer thick carbon cage yields rapid solid-state K-ion diffusion and prevents aggregation/pulverization of 40 nm cobalt phosphide.