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.
The growing demand for cost-effective and sustainable energy storage solutions has spurred interest in novel anode materials for lithium-ion batteries (LIBs). This study explores the potential of small molecule polycyclic aromatic hydrocarbons (SMPAHs) as promising candidates for LIB anodes. Through a comprehensive experimental approach involving electrode fabrication, material characterization, and electrochemical testing, the electrochemical performance of SMPAHs, including naphthalene, biphenyl, 9,9-dimethylfluorene, phenanthrene, p-terphenyl, and pyrene, is thoroughly investigated. The results reveal the impressive cycle stability, high specific capacity, and excellent rate capability of the SMPAH electrode. Additionally, a direct contact prelithiation strategy is implemented to enhance the initial Coulombic efficiency (ICE) of SMPAH anodes, yielding significant improvements in the ICE and cycle stability. Computational simulations provide valuable insights into the electrochemical behavior and lithium storage mechanisms of SMPAHs, confirming their potential as effective anode materials. The simulations reveal favorable lithium adsorption sites, the predominant storage mechanisms, and the dissolution mechanism of pyrene through computational calculations. Overall, this study highlights the promise of SMPAHs as sustainable anode materials for LIBs, advancing energy storage technologies toward a greener future.
Three VO2 polymorphs, namely monoclinic VO2 (B), monoclinic VO2 (M), and tetragonal VO2 (A), are synthesized, and their microstructures and electrochemical properties are studied for application in Zn-ion batteries (ZIBs). A cost-effective ZnSO4-based aqueous electrolyte with various concentrations (3 − 7 m) of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) additive is developed. The optimal ZnSO4/LiTFSI ratio in the electrolyte for superior Zn//VO2 battery properties is examined. The coordination structures of various electrolytes are investigated using wide-angle X-ray scattering. The incorporation of LiTFSI impairs the hydrogen-bonded network of H2O molecules and causes solvated-TFSI and TFSI‧‧‧TFSI structures to form, altering the electrolyte properties (such as electrochemical stability window, ionic conductivity, and Zn(OH)2)3(ZnSO4)·xH2O byproduct formation tendency). It is found that an excessive LiTFSI concentration leads to the formation of ion aggregates in the electrolyte and thus deterioration of electrode specific capacity and rate capability. Operando transmission X-ray microscopy observations confirm the high dimensional stability of the VO2 cathode during charging and discharging; the length variation of the VO2 (B) rods is approximately 10 %. The electrolyte composition also affects the Zn2+/Zn redox behavior at the anode side. The incorporation of LiTFSI into the electrolyte affects the Zn plating/stripping Coulombic efficiency, morphology of the deposited Zn, dead Zn amount, and anode cycle life. The constructed Zn//VO2 (B) cell with 1 m ZnSO4/5 m LiTFSI dual-salt electrolyte shows 90 % capacity retention after 1000 cycles. The proposed electrode material and electrolyte composition have great potential for applications in high-performance and high-stability rechargeable ZIBs.
