Feasibility Study of Single-Crystal Si Island Manufacturing by Microscale Printing of Nanoparticles and Laser Crystallization.

Nonvacuum printing of single crystals would be ideal for high-performance functional device (such as electronics) fabrication yet challenging for most materials, especially for inorganic semiconductors. Currently, the printed films are dominant in amorphous, polycrystalline, or nanoparticle films. In this article, manufacturing of single-crystal silicon micro/nano-islands is attempted. Different from traditional vapor deposition for silicon thin-film preparation, silicon nanoparticle ink was aerosol-printed followed by confined laser melting and crystallization, allowing potential fabrication of single-crystal silicon micro/nano-islands. It is also shown that as-fabricated Si islands can be transfer-printed onto polymer substrates for potential application of flexible electronics. The additive nature of this technique suggests a scalable and economical approach for high-crystallinity semiconductor printing.

Strengthening the Electrodes for Li-Ion Batteries with a Porous Adhesive Interlayer through Dry-Spraying Manufacturing.

The manufacturing technologies for electrodes have a great influence on the performance of Li-ion batteries. Manufacturing procedures largely determine the microstructure of electrodes, and thus affect how active materials are involved in the electrochemical reactions. However, the usage of solvent in the dominant slurry-casting method weakens its competence on obtaining desired microstructures and properties. In this study, an improved adhesion strength is achieved during the fabricaion of graphite anodes with our solvent-free manufacturing method. Through dry-spraying an interfacial "adhesion enhancer" layer between the current collector and the electrode coating, the mechanical strength (from 0.5 kPa to over 83.0 kPa) and electrochemical performance (from 24.2% to 92.4% as the capacity retention in 100 cycles) are significantly improved. Results here demonstrate a simple and economical route to practically control the microstructure of electrodes during manufacturing and potentiate the strategy enabled by dry-spraying to design and manufacture advanced batteries.

Low-Cost Manufacturing of Bioresorbable Conductors by Evaporation-Condensation-Mediated Laser Printing and Sintering of Zn Nanoparticles.

Currently, bioresorbable electronic devices are predominantly fabricated by complex and expensive vacuum-based integrated circuit (IC) processes. Here, a low-cost manufacturing approach for bioresorbable conductors on bioresorbable polymer substrates by evaporation-condensation-mediated laser printing and sintering of Zn nanoparticle is reported. Laser sintering of Zn nanoparticles has been technically difficult due to the surface oxide on nanoparticles. To circumvent the surface oxide, a novel approach is discovered to print and sinter Zn nanoparticle facilitated by evaporation-condensation in confined domains. The printing process can be performed on low-temperature substrates in ambient environment allowing easy integration on a roll-to-roll platform for economical manufacturing of bioresorbable electronics. The fabricated Zn conductors show excellent electrical conductivity (≈1.124 × 106 S m-1 ), mechanical durability, and water dissolvability. Successful demonstration of strain gauges confirms the potential application in various environmentally friendly sensors and circuits.

Solvent-Free Manufacturing of Electrodes for Lithium-ion Batteries.

Lithium ion battery electrodes were manufactured using a new, completely dry powder painting process. The solvents used for conventional slurry-cast electrodes have been completely removed. Thermal activation time has been greatly reduced due to the time and resource demanding solvent evaporation process needed with slurry-cast electrode manufacturing being replaced by a hot rolling process. It has been found that thermal activation time to induce mechanical bonding of the thermoplastic polymer to the remaining active electrode particles is only a few seconds. Removing the solvent and drying process allows large-scale Li-ion battery production to be more economically viable in markets such as automotive energy storage systems. By understanding the surface energies of various powders which govern the powder mixing and binder distribution, bonding tests of the dry-deposited particles onto the current collector show that the bonding strength is greater than slurry-cast electrodes, 148.8 kPa as compared to 84.3 kPa. Electrochemical tests show that the new electrodes outperform conventional slurry processed electrodes, which is due to different binder distribution.