Graphene, recognized for its impressive strength, flexibility, and conductivity, has garnered significant interest for numerous applications. Within energy storage sector, especially in battery technology, graphene shows promise for improving battery component performance. Graphene/silicon composites in lithium-ion batteries are gaining attention for their potential to overcome some of the challenges associated with silicon as a high-capacity anode material. Here we present an eco-friendly approach to fabricate graphene flakes, utilizing ball milling, ultrasonication, and spray drying to enable efficient mechanical transfer of graphene onto silicon particles. The technique employs a combination of dry/wet exfoliation and self-assembly, effectively eliminating the need for hazardous chemicals. The developed method illustrates the successful integration of silicon within a graphene envelope, resulting in a stable core-shell structure. Characterization techniques, such as scanning electron microscopy, tunneling electron microscopy, X-ray diffraction, and Raman spectroscopy, verify the quality and stability of the composite with graphene. Electrochemical assessments demonstrate that the composite composed of silicon wrapped in graphene has enhanced cycle stability when compared to pure silicon. Cross-sectional analysis of the microstructure reveals reduced volume expansion and improved structural stability of the electrode. This green synthesis method towards fabricating graphene-based composites holds enormous potential for promoting sustainable manufacturing practices.
The development of lithium-sulfur batteries (LSBs) marks a crucial milestone in advancing energy storage solutions essential for sustainable energy transitions. With high theoretical specific capacity, cost-effectiveness, and reduced ecological footprint, LSBs promise to enhance electric vehicle ranges, extend portable electronics' operational times, and stabilize grids integrated with renewable energy. However, challenges like complex processing, electrode instability, and poor cycling stability hinder their commercialization. This study introduces a novel battery design that addresses these issues by coating sulfur directly onto the separator instead of the current collector, demonstrating that active sulfur can be effectively utilized without being incorporated into the electrode structure. Using an interwoven substrate made from carbon nanotube (CNT) fabric adorned with reduced graphene oxide (rGO), this setup enhances manufacturing scalability, supports optimal sulfur utilization, and improves battery performance. The rGO decoration provides multiple highly conductive polysulfide trapping sites, enhancing active material reutilization, while the flexibility and mechanical strength of CNT fabric contribute to electrode integrity. This combination boosts electrical conductivity and polysulfide-capturing capability, effectively managing migrating sulfur species during charge-discharge cycles and mitigating sulfur loss and polysulfide shuttling. The results demonstrate superior cycling stability and efficiency, highlighting the potential of this approach in advancing LSB technology.
Advancing battery electrode performance is essential for high-power applications. Traditional fabrication methods for porous electrodes, while effective, often face challenges of complexity, cost, and environmental impact. Inspired by acupuncture, here we introduce aneco-friendly and cost-effective microneedle process for fabricating lithium iron phosphate electrodes. This technique employs commercial cosmetic microneedle molds to create low-curvature holes on electrode surfaces, significantly enhancing electrolyte infiltration and ion transport kinetics. The punctured electrodes were prepared and characterized, with comparisons to pristine electrodes conducted using scanning electron microscopy, 3D metallurgical microscopy, and detailed electrochemical evaluations. Our results show that the microneedle-processed electrodes exhibit superior rate performance and diffusion properties. Simulations and experimental data reveal that the low-curvature holes reduce Li-ion concentration polarization and improve Li-ion transport within the electrode. This enhancement leads to higher specific capacities and better rate capabilities in the punctured electrodes. The findings highlight the potential of this innovative microneedle technique for large-scale production of high-performance electrodes, offering a promising avenue for the development of high-power-density batteries.
