Design and controllable synthesis of core-shell nanostructured Ni-P particles with an ionothermal strategy

Designed core-shell nanostructured of Ni-P alloy particles are fabricated by a controllable ionothermal strategy. Based on advanced first-principles calculations, the Ni3P composite exhibit a decreased vacancy formation energy (6.130 eV) and diffusion activation energy (−0.347 eV) compared with those of Ni4.5P. Notably, the size and composition of the as-prepared Ni-P alloy nanoparticles can be effectively controlled by using different nickel (NiSO4·6H2O, NiCl2·6H2O, and Ni(NO3)2·6H2O) and pyrophosphate sources (NaH2PO2·H2O and NH4H2PO2). The structural information of the as-prepared particles is characteristic of an amorphous Ni-P solid solution which homogeneously covered by a self-generated crystalline nickel pyrophosphate shell. The thickness of the crystalline shell surrounding the amorphous core is dependent on the molar ratio of Ni2+/H2PO2− in the reaction solution. Furthermore, as negative electrode materials for lithium ion batteries, the Li storage behaviours of the as prepared Ni-P alloy nanoparticles are investigated by both electrochemical tests and first-principles calculations. Of the prepared nano particles, those samples with high P contents and small particle sizes exhibit improved capabilities and cycling performances. •Two different molar ratios of Ni and P compounds are designed by first-principles calculation.•Ni-P alloy particles with core-shell nanostructure are fabricated by a controllable ionothermal strategy.•Ni-P nano-particles with high P contents exhibit improved electrochemical performances.•The shell thickness of the Ni-P particles is highly dependent on the Ni2+:H2PO2− molar ratio.