In materials science education, crystallography is a fundamental but challenging subject for undergraduate students. Traditional teaching methods often leave students confined to abstract theories—they may memorize lattice parameters and calculate interplanar spacings yet fail to establish an empirical linkage between microscopic crystal structures and macroscopic material properties. This “cognitive gap” severely hinders their understanding of the core principle that “structure determines properties.” To address this issue, this study develops a comprehensive, semester-long experimental project centered on crystal structure engineering of vanadium-based cathodes for aqueous zinc-ion batteries (AZIBs). The project aims to transform cutting-edge research into a teachable investigative framework, thereby bridging theory and practice, enhancing students’ quantitative structure-analysis skills, and cultivating their ability to solve complex materials-science problems.

The experiment follows a project-based learning model conducted over an entire semester and divided into four progressive stages. First, students learn the fundamentals of AZIBs, vanadium oxide cathodes, and crystallography, and then design a detailed experimental plan for Mn²⁺ ntercalation into VOH layered structures. Second, they synthesize two materials—pristine VOH and Mn-intercalated VOH (Mn-VOH)—via a hydrothermal method, followed by standard characterizations such as X-ray diffraction (XRD) and scanning electron microscopy. Third, students are introduced to the research-grade GSAS-Ⅱ software and perform Rietveld full-pattern fitting refinement of the collected XRD data. They learn to establish structural models, refine parameters stepwise (e.g., scale factor, background, zero shift, unit cell parameters, profile parameters, atomic coordinates, occupancy, and thermal factors), and extract quantitative crystallographic data (e.g., lattice constants, cell volume, interlayer spacing). Fourth, students assemble coin cells, evaluate their electrochemical performance through cyclic voltammetry (CV), cycling stability, and electrochemical impedance spectroscopy (EIS), and finally integrate the refined structural parameters with the electrochemical data to prepare a comprehensive report demonstrating the structure–property correlation quantitatively.

The designed experiment successfully converted an abstract concept into a tangible, data-driven inquiry. XRD patterns showed that the (001) interlayer spacing of VOH increased from 11.43 to 12.81 Å after Mn²⁺ intercalation. Rietveld refinement (reliability factors R_wp < 10%) quantitatively revealed that the c-axis lattice parameter expanded by 15.7% (from 11.13 to 12.88 Å), while the unit cell volume enlarged from 988.84 to 1146.22 ų. This structural evolution directly correlated with enhanced electrochemical performance. Specifically, the Mn-VOH cathode exhibited reduced polarization (small peak potential separation in CV curves), significantly improved cycling stability (negligible capacity decay after 3000 cycles at 5 A g⁻¹, compared with only 60.18% capacity retention for pristine VOH), and fast Zn²⁺ diffusion kinetics, as evidenced by low charge-transfer resistance and a steep Warburg region in EIS measurements. Throughout the project, students not only mastered routine experimental skills, including hydrothermal synthesis, electrode preparation, and battery assembly, but also achieved a significant advancement in analytical capability—from merely “collecting XRD patterns” to “quantitatively solving crystal structures” using digital refinement tools. They directly observed how Mn²⁺ pillars expand the interlayer space and stabilize the lattice, thereby justifying the improved electrochemical performance.

This teaching reform effectively bridges the gap between fundamental crystallography education and advanced materials research. By integrating a real scientific problem and state-of-the-art analytical techniques, such as GSAS-Ⅱ-based Rietveld refinement, into a structured and extended experimental project, the approach fosters a deep understanding of structure–property correlations. The project provides a replicable model for “digital-integrated” practical teaching and helps cultivate the innovative thinking and problem-solving competencies essential for future materials scientists.