A General Route for Encapsulating Monodispersed Transition Metal Phosphides into Carbon Multi-Chambers toward High-Efficient Lithium-Ion Storage with Underlying Mechanism Exploration

Transition metal phosphides (MPx) with high theoretical capacities and low cost are regarded as the most promising anodes for lithium-ion batteries (LIBs), but the large volume variations and sluggish kinetics largely restrict their development. To solve the above challenges, herein a generic but effective method is proposed to encapsulate various monodispersed MPx into flexible carbon multi-chambers (MPx@NC, M(sic)Ni, Fe, Co, and Cu, etc.) with pre-reserved voids, working as anodes for LIBs and markedly boosting the Li+ storage performance. Ni2P@NC, one representative example of MPx@NC anode, shows high reversible capacity (613 mAh g(-1), 200 cycles at 0.2 A g(-1)), and superior cycle stability (475 mAh g(-1), 800 cycles at 2 A g(-1)). Full cell coupled with LiFePO4 displays a high reversible capacity (150.1 mAh g(-1) at 0.1 A g(-1)) with stable cycling performance. In situ X-ray diffraction and transmission electron microscope techniques confirm the reversible conversion reaction mechanism and robust structural integrity, accounting for enhanced rate and cycling performance. Theoretical calculations reveal the synergistic effect between MPx and carbon shells, which can significantly promote electron transfer and reduce diffusion energy barriers, paving ways to design high-energy-density materials for energy storage systems.

Automated summary

A new method is proposed to encapsulate transition metal phosphides (MPx) into flexible carbon multi-chambers as anodes for lithium-ion batteries (LIBs). The Ni2P@NC anode exhibits high reversible capacity and excellent cycle stability. The encapsulated structure promotes electron transfer and reduces diffusion energy barriers, providing a design strategy for high-energy-density energy storage materials.