Ultrafast Li-ion migration in eggshell-inspired 2D@2D dual porous construction towards high rate energy storage

Abstract

The rate performance of lithium-ion batteries is vital to their practical applications in electronics and vehicles, but impeded by limited migration of Li⁺ and electrons in solid anode materials. Inspired by the double-layer porous structure, a calciferous outer layer elegantly grown on a protein inner layer, of air-penetrable eggshells, a new composite is designed to have a 2D@2D dual porous architecture consisting of 2D holey graphene (hG) and 2D porous ZnFe₂O₄ nanobelts (ZFOnb@hG). In the composite Zn–Fe hybrid Prussian blue analog was transformed into 2D porous ZnFe₂O₄ nanobelts on a holey graphene matrix which acts as both template and substrate. The hG matrix in the dual porous structure can minimize Li⁺/electron transfer pathways and the 2D porous nanobelts consisting of ultrafine ZnFe₂O₄ nanoparticles (3−4 nm) can efficiently buffer the volume change in both lateral and thickness directions during lithiation/delithiation. The resultant composite ZFOnb@hG exhibited an ultrahigh capacity of 1305 mA h g⁻¹ after 250 cycles at 0.2 A g⁻¹ and outstanding rate performance with excellent cycling stability of 703 mA h g⁻¹ retained after 10000 cycles at 10 A g⁻¹. This biomimetic study opens up a new avenue for the development of high-capacity anode materials towards fast-charging capabilities.