The investigation into intercalation mechanisms in vanadium pentoxide has garnered significant attention within the realm of research, primarily propelled by its remarkable theoretical capacity for energy storage. This comprehensive review delves into the latest advancements that have enriched our understanding of these intricate mechanisms. Notwithstanding its exceptional storage capacity, the compound grapples with challenges arising from inherent structural instability. Researchers are actively exploring avenues for improving electrodes, with a focus on innovative structures and the meticulous fine-tuning of particle properties. Within the scope of this review, we engage in a detailed discussion on the mechanistic intricacies involved in ion intercalation within the framework of vanadium pentoxide. Additionally, we explore recent breakthroughs in understanding its intercalation properties, aiming to refine the material’s structure and morphology. These refinements are anticipated to pave the way for significantly enhanced performance in various energy storage applications.

LiFePO₄ is a common electrode cathode material that still needs some improvements regarding its electronic conductivity and the synthesis process in order to be easily scalable. In this work, a simple, multiple-pass deposition technique was utilized in which the spray-gun was moved across the substrate creating a “wet film”, in which—after thermal annealing at very mild temperatures (i.e., 65 °C)—a LiFePO₄ cathode was formed on graphite. The growth of the LiFePO₄ layer was confirmed via X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy. The layer was thick, consisting of agglomerated non-uniform flake-like particles with an average diameter of 1.5 to 3 μm. The cathode was tested in different LiOH concentrations of 0.5 M, 1 M, and 2 M, indicating an quasi-rectangular and nearly symmetric shape ascribed to non-faradaic charging processes, with the highest ion transfer for 2 M LiOH (i.e., 6.2 × 10⁻⁹ cm²/cm). Nevertheless, the 1 M aqueous LiOH electrolyte presented both satisfactory ion storage and stability. In particular, the diffusion coefficient was estimated to be 5.46 × 10⁻⁹ cm²/s, with 12 mAh/g and a 99% capacity retention rate after 100 cycles.

LiFePO4 is a widely used lithium-ion battery cathode material owing to its environmental benignity, low cost, safe ~3.45 V operating voltage, and thermal stability. However, its low electronic conductivity and limited lithium-ion diffusion restrict its electrochemical performance. In this work, an eco-friendly hydrothermal route was developed to synthesize LiFePO4/rGO nanocomposites at 140 °C for 20 h using an aqueous three-reagent system. Unlike most reported studies, where graphene derivatives are added after LiFePO4 formation, this method enables in situ interaction between GO and the precursor system during composite formation, promoting effective interfacial coupling. To assess the role of GO chemistry, composites from the conventional Hummer's method were compared with those from an eco-friendly, NaNO3-free oxidation route. Materials were characterized by Rietveld-refined XRD, Raman spectroscopy, XPS, SEM, and electrical measurements. Raman analysis showed a lower ID/IG ratio for the eco-friendly composite (0.52 vs. 1.03), indicating higher graphitization and fewer defects. XRD confirmed phase-pure olivine LiFePO4 in all samples, with the eco-friendly LiFePO4/rGOFR composite showing enhanced crystallinity without compromising the olivine structure. Electrical measurements revealed conductivities of ~10⁻⁴ S/cm, a five-order-of-magnitude improvement over pristine LiFePO4. These findings highlight the importance of GO chemistry in producing highly conductive LiFePO4/rGO composites for advanced energy storage.