Lithiophilic Nickel Phosphide Modifying Carbon Nanofibers for a Highly Reversible Lithium-Metal Anode

A lithium (Li)-metal battery with high energy density is the most promising system for the next-generation battery. However, detrimental Li dendrite growth induced by uneven Li deposition causes inferior Coulombic efficiency (CE) and infinite volumetric expansion of Li-metal anodes. Herein, a flexible carbon nanofiber membrane modified by nickel phosphide (Ni2P@CNF) is proposed as an effective 3D framework to guide Li deposition behaviors. Even and dense deposition of Li is observed via ex situ/in situ morphological observations, ascribed to the homogeneous Li nucleation on the lithiophilic Ni2P crystalline grains. The efficient utilization of Li is achieved benefiting from the synergistic reversible conversion reactions between Li and Ni2P and plating/stripping of Li. Moreover, the fibrous networks of Ni2P@CNF retain structural stability upon prolonged cycling. Thus, an average CE of 97.6% at 5 mA cm–2 is available. And an extended lifespan of 2000 h at 0.5 mA cm–2 for a symmetrical cell of Ni2P@CNF@Li and 1000 cycles at 5 C (1 C = 170 mA g–1) for a Li||LiFePO4 cell are attained, revealing the great potential of a practical Li-metal anode.