Asymmetric Configuration of Amorphous Mn–S Adjacent to Low-Nucleated MnS in N-Doped Carbon for Advanced Sodium-Ion Hybrid Capacitors

Addressing the kinetic mismatch and structural instability challenges in sodium-ion hybrid capacitor (SIHC) anodes, this study develops an N-doped carbon composite integrating amorphous Mn-S with adjacent low-nucleated MnS (a-Mn-S/MnSLN@NC). This architecture synergistically enhances mechanical stress buffering and charge transfer kinetics via the isotropic dynamic bonding of a-Mn-S and the high-affinity sites of MnSLN. The 3D C-S-Mn covalent bonds in the a-Mn-S stabilize MnSLN through atomic anchoring, homogenizing volume strains and exposing uncoordinated S active sites to elevate Na⁺ adsorption density. Theoretical calculations reveal that the proximity-induced d-p orbital hybridization reconstructs the electron-donor characteristics of S sites, creating an asymmetric electronic configuration. The electron-rich a-Mn-S serves as efficient Na⁺ trapping centers, while the electron-deficient MnSLN facilitates rapid electron transfer. This configuration endows the composite with superior Na⁺ adsorption energy and charge transfer efficiency over pure MnS. Consequently, the a-Mn-S/MnSLN@NC anode delivers a high reversible capacity of 597 mAh g⁻¹ at 0.1 A g⁻¹ and retains 90.5% capacity after 3500 cycles at 10.0 A g⁻¹. The assembled SIHCs achieve exceptional energy/power densities (186 Wh kg⁻¹ and 9576 W kg⁻¹). This work elucidates the mechanism of adjacent asymmetric configurations for enhanced Na⁺ storage, offering a novel strategy for designing high-performance SIHCs.