Mesoporous N-rich carbon nanospheres regulating high dispersion of red phosphorus for sodium-ion batteries

The intrinsic insulation and drastic volume change of the red phosphorus during the 3-electron alloying process greatly limits its widespread applications in sodium-ion batteries. Here, we report a monomicelle-directed assembly approach for controllable synthesis of monodispersed mesoporous polypyrrole (PPy) nanospheres, which allows for the shape-preserving conversion into N-doped carbon with regular mesoscopic pore and high surface area, thus affording a high dispersion of red phosphorus during melt impregnation process due to the available diffusion apertures and strong molecular chemical anchoring. Moreover, the theoretical calculations further revealed that positively polarized pyridine N atoms in N-doped mesoporous carbon nanospheres can empower comprehensive regulation of red phosphorus adsorption by strong chemical binding. Benefitting from the above advantages, the resultant red phosphorus host for sodium-ion batteries delivered an outstanding reversible capacity of 856 mAh/g with a capacity fading rate of only 0.025 % per cycle during 1000 cycles at 1.0 A/g. This work provides an effective approach based on monomicelle-directed assembly engineering of carbon-based phosphorus hosts for advanced energy conversion and storage systems.