Heterogeneous Carbon Designed with Disorder-in-Ordered Nanostructure toward High-Rate and Ultra-stable Sodium Ion Storage

The rate performance of biomass-based hard carbon has always been one of the obstacles to its large-scale use. There are various challenges in improving the rapid conduction of sodium ions at the interface and realizing the efficient utilization of inactive carbon in large current. In this study, a disorder-in-ordered nanostructure carbon front-face coated with hard carbon which forms a heterogeneous carbon is prepared by coulomb adsorption of methylene blue and alkalized kapok fiber. A study on heterogeneous hard carbon material formation is proposed by incorporating heteroatoms at different carbonization temperatures. When the current density increases to 10 A g⁻¹, the obtained carbon material shows stable cycling for 5000 cycles with only a decay rate of 0.056 ‰, which is significantly better than conventional biomass-based hard carbon materials. This work provides insights of synergistic effect into the achievement of superior rate capability, that is the internal heteroatoms facilitates the activation of deep sodium energy storage, while the external well-ordered interface enhances the transport of sodium ions. The evolution of heterogeneous structure is analyzed, offering a novel perspective on the utilization of alkalized kapok for wastewater recovery and energy storage applications.