Phosphorus doped carbon nanosheets encapsulated Cu3P heterostructure for superior lithium storage by experimental verification and first-principles calculation

Abstract

As a transition metal phosphide, copper phosphide (Cu3P) undergoes high volume expansion and reduced electrical conductivity during cycling, causing kinetic issues and rapid capacity fading. The well-dispersed and sheet-like structure of individual nano-copper phosphide particles is crucial for alleviating volume expansion and enhancing kinetic behavior, which however have been rarely concerned. In this work, we report a novel heterostructure with nano-copper phosphide particles immobilized on phosphorus doped carbon nanosheet (Cu3P@PCNSs) by using Cu-BDC as the precursor. When the synthesis temperature is 600 ◦C, the Cu3P@PCNSs-600 exhibits a remarkable rate capability (383.4 mA h g−1 at 2 A g−1) and outstanding long-term durability (436.4 mA h g−1 at 1000 mA g−1 after 1000 cycles) for lithium storage. The monodisperse structure of Cu3P nanoparticles embedded in phosphorus doped carbon could reduce the volume change of Cu3P nanoparticles. Moreover, the electron density, adsorption energy, diffusion barrier and other properties of Cu3P and carbon matrix heterostructures were calculated in accordance with density functional theory (DFT). As dndicated by the calculation, the strong interaction between the heterostructures had an effect on the adsorption capacity of Li, and the experimental results were confirmed to be correct. This novel Cu3P@PCNSs electrode can be used as an effective strategy for applying other transition metal electrode materials in lithium-ion batteries.