Preparation and theoretical study of histidine-intercalated hydrotalcite–montmorillonite composite as a promising solid electrolyte
摘要
A histidine-intercalated hydrotalcite–montmorillonite composite (His-LDHs-MMT) was synthesized via an exfoliation–reassembly strategy. In this architecture, zwitterionic histidine acts as a molecular bridge to mediate the assembly of cationic hydrotalcite (LDHs) and anionic montmorillonite (MMT), effectively integrating the complementary structural and functional attributes of these two layered materials. The morphological, structural, and thermal properties of the prepared composite were systematically characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetry–differential thermal analysis (TG-DTA), and X-ray diffraction (XRD). Ratio analysis revealed that the composite retains the dual characteristics of LDH and MMT within the L/M ratio range of 4:1 to 6:1. Furthermore, the structural model of the composite was theoretically constructed and optimized through density functional theory (DFT) calculations. The validity of the proposed model was substantiated by the close agreement between the simulated parameters and experimental results. Total density of states (TDOS) analysis revealed an intrinsic band gap of 0.51 eV, which can be significantly widened to 1.36 eV under an external electric field, demonstrating its potential utility as a solid electrolyte. Electrochemical evaluations further confirmed that the His-LDHs-MMT exhibits favorable and reliable ion transport performance, with an ionic conductivity reaching 4.21 × 10−5 S/cm. Benefiting from enhanced thermal stability and stable layered structure, the composite exhibits more balanced comprehensive performance than that of single precursors, showing promising prospects in solid-state lithium batteries and advanced electrochemical energy storage systems.