Construction of N-doped porous carbon-coated Fe3O4 with efficient ion transfer performance for enhanced-performance lithium storage

Abstract

Fe3O4 has become one of the most promising anode candidates for lithium-ion batteries owing to its high capacity, low cost, rich abundance, and environmental friendliness. However, its poor conductivity and inherent volume expansion in the conversion reaction process (Fe3O4 + 8Li+ + 8e−→3Fe0 + 4Li2O) seriously hinder its development as anode material. In this work, N-doped porous carbon-coated Fe3O4 (Fe3O4@PNC) is designed to solve this problem by using dopamine as the carbon and nitrogen source and cetyltrimethylammonium bromide (CTAB) as the defect inducer. The addition of CTAB can facilitate the formation of a hybrid carbon layer and construct a hierarchical porous structure, thereby promoting electrolyte penetration and Li-ion transfer. As a result, the Fe3O4@PNC can maintain a high reversible capacity of 988.2 mAh g−1 at a current density of 200 mA g−1 after 100 cycles and excellent cyclability of 908.5 mAh g−1 even after 300 cycles, while the N-doped carbon-coated Fe3O4 (Fe3O4@NC) can only deliver 779 mAh g−1 after 100 cycles. Moreover, the superior Li+ transfer and great pseudocapacitance effect enable the cell to exhibit 483 mAh g−1 capacity even at 2000 mA g−1. This study provides guidance for the shipment of porous carbon coating for the metal oxide anode materials to enhance their electrochemical performance and stability.