Silicon anodes in lithium-ion batteries suffer from severe volume change and sluggish through-plane ion transport in stacked graphene hosts. Here we report a dual-modulation strategy that couples thermal reduction with controlled H2O2 etching to build a holey reduced graphene oxide (HRGO) framework around silicon. Reduction restores a continuous graphitic network while maintaining a compact interlayer structure; subsequent oxidative etching perforates the basal planes and modestly expands the interplanar galleries relative to reduced graphene oxide (RGO), creating short, wide Li⁺ pathways. Across various silicon-graphene composite materials, multi-modal characterization verifies defect/porosity tuning and etching-driven spacing expansion, consistent with enhanced battery performance. Electrochemically, Si–HRGO delivers stable cycling (1659 mAh g−1 after 300 cycles, 72.6% retention at 0.5 C) with suppressed swelling, higher capacitive contribution, faster Li⁺ diffusion, and reduced impedance growth. XPS depth profiling reveals an inorganic-rich solid electrolyte interphase (Li2O/LiF/lithium silicates) and deeper lithium retention within HRGO matrices, supporting durable interfacial chemistry. The combined interplanar-spacing modulation and holey architecture co-optimize ion transport, mechanical compliance, and interfacial stability via a scalable process. This framework is generalizable to other 2D material hosts and beyond-Li chemistries where through-plane flux and structural resilience are concurrently required.
Advancing lithium-sulfur batteries (LSBs) toward practical commercialization necessitates separator designs that effectively balance pore structure with interfacial chemical functionality. In this study, a unique separator architecture featuring hierarchical carbon microspheres, comprising multiscale porous carbon (MPC) cores encapsulated within functionalized reduced graphene oxide (rGO) shells, is proposed. This structure systematically optimizes pore distribution and surface chemistry to improve lithium polysulfide (LiPS) retention, electrolyte penetration, and electrochemical stability under high sulfur loading and lean electrolyte conditions. Compared to traditional porous separators, the rGO/MPC-coated separator demonstrates significantly enhanced LiPS trapping capability and superior cycling stability, achieving a high initial discharge capacity of 1532 mAh g−1 at 0.1C, sustained capacity retention (decay of only 0.13% per cycle over 300 cycles), and excellent rate capability (944 mAh g−1 at 4C). These results point out the critical role of synergistically tuning porosity and chemical functionalities, establishing a new benchmark for separator engineering in high-performance LSBs.
Sodium-ion batteries (SIBs) are promising alternatives to lithium-ion systems, yet the development of suitable anode materials remains a major challenge due to the large ionic radius of Na+ and its poor intercalation in graphite. Here, we conduct the first systematic investigation of six unsubstituted π-conjugated arenes as molecular model systems to probe Na+-π interactions and their implications for Na+ storage. Through comprehensive electrochemical measurements, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy depth profiling, and density functional theory (DFT) simulations, we explore how structural features influence reversible Na+ storage and dissolution resistance. Among the tested arenes, naphthalene, biphenyl, and 9,9-dimethylfluorene exhibit high reversible capacities, moderate initial Coulombic efficiencies, and outstanding cycling stability, attributed to their rigid, insoluble structures and stable SEI formation. In contrast, phenanthrene, p-terphenyl, and pyrene suffer from severe dissolution and capacity fading. DFT calculations further correlate favorable Na adsorption energies and minimal volume expansion with the experimentally observed stability of specific arenes. A direct-contact presodiation approach significantly improves the initial Coulombic efficiency and long-term performance of DiMF-based electrodes. This study provides comparative dataset of unsubstituted arenes in SIBs and suggests preliminary structure–function relationships that may inform future molecular design, while emphasizing the multifactorial nature of Na+-π interactions.
