Lithium–sulfur (Li–S) batteries are promising for high-energy storage but are limited by complex multistep sulfur redox reactions that induce polysulfide migration, sluggish conversion kinetics, and severe cathode swelling. Here, we report a boron nitride/carbon nanotube (BN/CNT) heterostructure that enables electrostatic regulation of sulfur spatial evolution through the separation of polar domains and conductive networks. The conductive CNT scaffold preserves electron percolation, whereas the BN interlayer provides abundant polarity to regulate polysulfide interactions. Amine functionalization (BN–NH2) further tailors the local electronic environment and interfacial charge distribution. Consequently, sulfur spatial evolution is regulated toward homogeneous redistribution rather than surface overaccumulation, resulting in near-zero cathode swelling during prolonged cycling. The optimized BN–NH2/CNT configuration delivers an initial capacity of 1089 mAh g−1 with stable cycling, reduced polarization, and enhanced rate capability. Potentiostatic nucleation analysis, nano-X-ray fluorescence mapping, depth-resolved X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy reveal stabilized sulfur redox chemistry and regulated sulfur electronic environments. Density functional theory calculations reveal interfacial charge redistribution and optimized interaction strengths that support regulated sulfur redox chemistry. In this work, moderated electrostatic regulation of sulfur spatial evolution is established as a design principle for dimensionally stable and kinetically optimized Li–S cathodes beyond adsorption-centric strategies.
DOI: 10.1002/smll.75698
Silicon (Si) anodes suffer from severe volume expansion and unstable solid electrolyte interphase (SEI), limiting their practical application in lithium-ion batteries. Here, we present Si–MoS2 composite anodes that are constructed via liquid-phase exfoliation of MoS2 followed by spray-drying integration with Si. Bath ultrasonication produces thin-flake MoS2 with reduced stacking coherence and expanded interlayer spacing (~0.625 nm), enabling a more uniform composite structure and improved dispersion of Si particles. Composition screening identifies Si–MoS2 (thin, 50:50) as the optimal configuration, delivering 1083 mAh g−1 after 300 cycles, significantly outperforming the thick-flake counterpart fabricated by probe ultrasonication (688 mAh g−1). Electrochemical impedance spectroscopy (EIS) reveals lower interfacial resistance, while X-ray photoelectron spectroscopy (XPS) indicates reduced surface coverage by SEI species in the thin-flake composite. In addition, the thin-flake electrode exhibits more stable voltage profiles with reduced polarization during cycling. Cross-sectional analysis shows minimal thickness expansion (~8%) compared to severe swelling (~115%) in the thick-flake electrode, highlighting substantial differences in mechanical stability. These results indicate that the electrochemical contribution of MoS2 is limited under the applied voltage window, and that it primarily functions as a structural and interfacial regulator. This work demonstrates that controlling the exfoliation state of MoS2 provides an effective strategy to regulate interfacial stability and mechanical integrity, offering practical guidance for the design of durable high-capacity Si-based anodes.
Lithium metal is a promising material for high-energy-density batteries, yet its electrochemical behavior is strongly influenced by the poorly controlled initial surface state of commercial lithium foils. Variations arising from manufacturing, storage, and handling introduce interfacial heterogeneity, leading to performance scatter and limited reproducibility across studies. Herein, we establish a modular standard operating procedure (SOP) to systematically regulate lithium metal interfaces prior to testing. The SOP decomposes lithium pretreatment into three functionally distinct steps: chemical etching (E) to remove native surface layers, mechanical brushing (B) to homogenize surface geometry, and solution soaking (S) to induce a controlled artificial solid electrolyte interphase. Using symmetric Li||Li cells, the integrated E–B–S sequence exhibits improved voltage stability and suppressed interfacial resistance growth compared with partial or no treatments. Structural and interfacial analyses using SEM, lithium-sensitive EDX, AFM, and EIS reveal the formation of a three-dimensionally structured yet chemically uniform lithium surface. Density functional theory calculations and depth-resolved XPS further clarify the chemical origins of controlled etching and interphase formation. The standardized lithium interface is validated in Li||LiFePO4 full cells, demonstrating enhanced capacity retention, reduced polarization, and improved rate capability. This work provides a transferable and reproducible framework for lithium metal interface standardization.
