Ultrafine Ni5P4 nanoparticles embedded in 3D porous carbon foams for high-performance lithium-ion and potassium-ion batteries

Ultrafine Ni5P4 nanoparticles embedded in 3D porous carbon foams are designed and synthesized by the assistance of NaCl templating and followed a phosphorization treatment. The three-dimensional porous structure of the carbon foams possesses large active specific surface areas and sufficient pores, that help to buffer the volume expansions whilst offering conductive pathways to accelerate ion transportations. The ultrafine Ni5P4 nanoparticles are beneficial for the exposure more accessible active sites to enhance the capacity utilization and shorten ion transport distances. The Ni5P4/C composite presents high rate capability with a specific capacity of 192.5 mAh g-1 at 8000 mA g-1 and high cycle stability (363.7 mAh g-1 at 2000 mA g-1 after 3000 cycles) for lithium-ion batteries. Further, the composite is also examined as the anode for potassium ion batteries for the first time and it delivers a high specific capacity of 128.1 mAh g-1 after 5000 cycles at the current density of 2000 mA g-1. XRD measurements suggests a solid-solution reaction mechanism for K-ion storage in Ni5P4.