Self-crosslink assisted synthesis of 3D porous branch-like Fe3O4/C hybrids for high-performance lithium/sodium-ion batteries

Abstract

A facile and effective self-crosslink assisted strategy is developed to fabricate 3D porous branch-like Fe₃O₄/C hybrids as high-performance anode materials for lithium ion batteries (LIBs) and sodium ion batteries (NIBs). Trivalent iron ions (Fe³⁺) are used to directly crosslink with biopolymer alginate to form nanoscale branch-like Fe-alginate hybrid nanostructures, which are converted to porous Fe₃O₄/C hybrids via a simple carbonization process. The resulting hybrids feature ultrafine active nanoparticles (∼5 nm), wrapping by thin graphitic layers, hierarchically nanoscale porous channels, and interconnected robust graphitic frameworks. Applying these in the anodes of LIBs, these structural features enable the hybrids to deliver high capacities of 974 and 570 mA h g⁻¹ at 0.1 and 2 A g⁻¹, respectively, and excellent cyclic stability with capacity retention of 98% after 200 cycles at 0.1 A g⁻¹. In NIBs, reasonable capacities of 339 and 138 mA h g⁻¹ are obtained at 0.05 and 5 A g⁻¹, respectively. The high performance demonstrates the promising potential of the hybrids in next generation anodes for LIBs and NIBs.