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

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/MnS_LN@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 MnS_LN. The 3D C-S-Mn covalent bonds in the a-Mn-S stabilize MnS_LN 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 MnS_LN 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/MnS_LN@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.