arXiv subjects

Qiye Guan

Publications and source records attributed to Qiye Guan.

6 recordsLinked to original sources

arXiv2026

Unraveling Lithium Dynamics in Solid Electrolyte Interphase: From Graph Contrastive Learning to Transport Pathways

Fast lithium transport across the solid-state electrolyte (SSE)/lithium metal anode interface is critical for high-performance all-solid-state batteries. Uncovering the complex lithium dynamics governed by diverse local environments in the solid electrolyte interphase (SEI) is fundamental for performance optimization. However, a general framework for characterizing these distinct local environments and the associated transport mechanisms remains lacking. Here, we develop GET-SEI, a general framework that discovers local atomic environments without predefined labels through Graph contrastive learning (GCL), models lithium transition kinetics via Extended dynamic mode decomposition (EDMD), and quantifies reactive lithium flux through Transition path theory (TPT). Applied to different SSE/Li systems, including sulfides (Li6PS5Cl/Li, Li10GeP2S12/Li) and oxides (Li7La3Zr2O12/Li), the GET-SEI reveals dominant transport pathways and kinetic bottlenecks in each system, providing quantitative metrics for evaluating lithium transport efficiency. As novel high-performance SSEs continue to emerge, GET-SEI offers a widely applicable, interpretable tool for targeted SEI engineering.

cond-mat.mtrl-sci↗

arXiv2025

Path Entropy-driven Design of Solid-State Electrolytes

The development of high-performance solid-state electrolytes (SSEs) has entered a critical stage, where entropy-driven strategies offer transformative potential for enhancing electrochemical properties. By engineering local environments for conductive ions alongside introducing disorder, these approaches can significantly improve conductivity. However, embracing high-entropy designs does not always guarantee improved performance. Current entropy descriptions oversimplify disorder by accounting solely for host framework configurations, neglecting conductive ion-induced disorder, rendering such descriptions incomplete. Herein, we propose path entropy (Sp) as a descriptor that quantifies diffusion pathway diversity, directly capturing diffusional disorder. Combining Markov state model with transition path theory, we reveal the interplay between diffusion pathway diversity of lithium and microscopic local environments in inorganic thiophosphates. Generalizing this path-informative Sp for high-throughput screening, we demonstrate its broad applicability in identifying and designing high-performance SSEs. Our work establishes a critical link between entropy evolution underlying ion conduction and practical entropy-driven design principles.

cond-mat.mtrl-sci↗

arXiv2024

Ferroelasticity in Two-Dimensional Hybrid Ruddlesden$-$Popper Perovskites Mediated by Cross-Plane Intermolecular Coupling and Metastable Funnel-Like Phases

Ferroelasticity describes a phenomenon in which a material exhibits two or more equally stable orientation variants and can be switched from one form to another under an applied stress. Recent works have demonstrated that two-dimensional layered organic$-$inorganic hybrid Ruddlesden$-$Popper perovskites can serve as ideal platforms for realizing ferroelasticity, however, the ferroelastic (FE) behavior of structures with a single octahedra layer such as (BA)$_2$PbI$_4$ (BA = CH$_3$(CH$_2$)$_3$NH$_3$$^+$) has remained elusive. Herein, by using a combined first-principles and metadynamics approach, the FE behavior of (BA)$_2$PbI$_4$ under mechanical and thermal stresses is uncovered. FE switching is mediated by cross-plane intermolecular coupling, which could occur through multiple rotational modes, rendering the formation of FE domains and several metastable paraelastic (PE) phases. Such metastable phases are akin to wrinkled structures in other layered materials and can act as a "funnel" of hole carriers. Thermal excitation tends to flatten the kinetic barriers of the transition pathways between orientation variants, suggesting an enhanced concentration of metastable PE states at high temperatures, while halogen mixing with Br raises these barriers and conversely lowers the concentration of PE states. These findings reveal the rich structural diversity of (BA)$_2$PbI$_4$ domains, which can play a vital role in enhancing the optoelectronic properties of the perovskite and raise exciting prospects for mechanical switching, shape memory, and information processing.

cond-mat.mtrl-sci↗

arXiv2022

Strongly Modulated Exfoliation and Functionalization of MXene with Rational Designed Groups in Polymer: A Theoretical Study

As emerging atomically ultrathin metal compounds, MXenes show great promise for catalysts and nanoelectronics applications due to the abundant surface terminations and high metallic conductivity. However, the tendency of the interlayer adhesion and suffering from environmental disturbances significantly limit their endurance and efficiency. Herein via conducting first-principles calculations, we explore surface passivation and exfoliation of MXene via polymers which have been experimentally proven to promote the performance. Nine kinds of monomers together with the typical MXene Ti3C2T2 (T= None, O, F, OH, F0.5O0.5) as prototype composites are explored with respect to the adsorption and charge transfer associated with energetics and chemical redox, respectively. Our work shows that naked Ti3C2 MXene has a strong ability to cleave and decompose the monomers. Surface functionalized Ti3C2F2, Ti3C2FO, and Ti3C2O2 have a weak binding with monomers through only van der Waals force, whereas Ti3C2(OH)2 also exhibits strengthened binding for some monomers. Specific functional groups in the monomer, such as the halogen, sulfur, and hydroxyl groups or a relatively planar aromatic structure, largely contribute to the adsorption. We reveal that the functionalization through polymer would alter the carriers' density via interfacial charge transfer in MXenes. While the naked Ti3C2 and Ti3C2(OH)2 donate electrons to the polymers, the Ti3C2F2, Ti3C2FO, and Ti3C2O2 receive small amounts of electrons transferred from the polymer, highly depending on the types of the monomers. The varying ability of charge transfer and exfoliation energy of different monomers implies great flexibility for designing polymers to exfoliate the MXene and modulate the carrier densities which is highly desired for altering conductivity, dielectric properties, and promoted endurance.

cond-mat.mtrl-sci↗

arXiv2022

Efficient Passivation of Surface Defects by Lewis Base in Lead-free Tin-based Perovskite Solar Cells

Lead-free tin-based perovskites are highly appealing for the next generation of solar cells due to their intriguing optoelectronic properties. However, the tendency of Sn2+ oxidation to Sn4+ in the tin-based perovskites induces serious film degradation and performance deterioration. Herein, we demonstrate, through the density functional theory based first-principle calculations in a surface slab model, that the surface defects of the Sn-based perovskite FASnI3 (FA = NH2CHNH2+) could be effectively passivated by the Lewis base molecules. The passivation performance of Lewis base molecules in tin-based perovskite is tightly correlated with their molecular hardness. We reveal that the degree of hardness of Lewis adsorbate governs the stabilization via dual effects: first, changing the stubborn spatial distribution of tin vacancy (VSn) by triggering charge redistribution; second, saturating the dangling states while simultaneously reducing the amounts of deep band gap states. Specifically, the hard Lewis base molecules like edamine (N-donor group) and Isatin-Cl (Cl-donor group) would show a better healing effect than other candidates on the defects-contained tin-based perovskite surface with a somehow hard Lewis acid nature. Our research provides a general strategy for additive engineering and fabricating stable and high-efficiency lead-free Sn-based perovskite solar cells.

physics.chem-ph↗

arXiv2022

Flatten the Li-ion Activation in Perfectly Lattice-matched MXene and 1T-MoS2 Heterostructures via Chemical Functionalization

MXene and its derivatives have attracted considerable attention for potential application in energy storage like batteries and supercapacitors owing to its ultrathin metallic structures. However, the complexity of the ionic and electronic dynamics in MXene based hybrids, which are normally needed for device integration, triggers both challenges and opportunities for its application. In this paper, as a prototype of metallic hybrids of MXene, heterostructures consisting of Ti3C2T2 (T= None, O and F atoms) and metallic MoS2 (1T phase) are investigated. Through density functional theory, we investigate the interfacial electronic variation, thermal activation, and anode performance in the lithium-ion battery (LIB) of Ti3C2T2/1T-MoS2. We found that different surface atomic groups in MXene can significantly alter the affinity, redox reaction and kinetics of Li atoms in the interface of the Ti3C2T2 and 1T-MoS2. Through examining the three possible pathways of Li by climbing image-nudged elastic band (CI-NEB) and ab-initio molecular dynamics (AIMD) simulation, the diffusion curve becomes significantly flattened from the naked to O- and F-terminated Ti3C2 MXene with activation barriers reducing from 0.80 to 0.22 and 0.29 eV, respectively, and room-temperature diffusion coefficients increasing from 1.20x10-6 to 2.75x10-6, 1.70x10-4 cm2 s-1, respectively. The functionalization with O or F eliminates the steric hindrance of Li intercalation by breaking the strong interaction between two layers and provides additional adsorption sites for Li diffusion in the meantime. Our work suggests that surface functional groups play a significant role in Ti3C2T2/1T-MoS2 modification and Ti3C2F2/1T-MoS2 with the high diffusion coefficient and theoretical capacity could be a promising anode material for LIBs.

cond-mat.mtrl-sci↗