Designing and preparing carbon anode materials modified with N and Fe-nanoparticle: Creating the interior electric field to improve their electrochemical performance

The increasing market demand calls for novel anode materials with low cost, high capacity, good rate performance, and high cycle stability. Here we report a facile method for preparing chitosan-derived and N-doped carbon composite (Fe-CDNC) decorated with Fe nanoparticles (NPs) as an efficient carbon anode material. The prepared Fe-CDNC composite could deliver a high reversible lithium capacity of 770 mAh g⁻¹ at 100 mA g⁻¹, much higher than that of both the bare CDNC (426 mAh g⁻¹) and the theoretical capacity of commercial graphite (372 mAh g⁻¹). The retention of lithium and sodium capacity was 95.5% after 10000 cycles and 98.7% after 5000 cycles at 2000 mA g⁻¹, respectively, and thus the lithium and sodium capacity loss rates were 0.00045% and 0.00026% per cycle, respectively. Density functional theory calculations revealed that the strong coupling between the Fe NPs and the N-doped carbon layer via Fe-N bond formation contributed to constructing a built-in electric field, which boosted ions/charge diffusion dynamics, leading more lithium ions to be inserted/extracted to carbon layer during the lithiation/delithiation processes. Therefore, the Fe-CDNC composite performed an outstanding rate performance, cycle stability, and high reversible capacity. This work is promising to develop novel carbon anode materials for high-energy storage devices.