Deflecting lithium dendritic cracks in multi-layered solid electrolytes

Charging current densities of solid-state batteries with lithium metal anodes and ceramic electrolytes are severely limited due to lithium dendrites that penetrate the electrolyte leading to a short circuit. We show that dendrite growth can be inhibited by different crack deflection mechanisms when multi-layered solid electrolytes, such as Li6PS5Cl/Li3ScCl6/Li6PS5Cl and Li6PS5Cl/Li10GeP2S12/Li6PS5Cl, are employed but not when the inner layer is Li3PS4. X-ray tomographic imaging shows crack deflection along mechanically weak interfaces between solid electrolytes as a result of local mismatches in elastic moduli. Cracks are also deflected laterally within Li3ScCl6, which contains preferentially oriented particles. Deflection occurs without lithium being present. In cases where the inner layers react with lithium, the resulting decomposition products can fill and block crack propagation. All three mechanisms are effective at low stack pressures. Operating at 2.5 MPa, multi-layered solid electrolytes Li6PS5Cl/Li3ScCl6/Li6PS5Cl and Li6PS5Cl/Li10GeP2S12/Li6PS5Cl can achieve lithium plating at current densities exceeding 15 mA cm–2

Design principles for LiFePO₄ electrodes with improved recyclability †

To improve sustainability of lithium-ion battery electrodes there is a need to design in recycling at the manufacturing stage. In this work, a method to improve LiFePO4 recovery rates through binder and electrode microstructure design is presented. Electrodes are produced by tape cast and direct ink writing methods with biopolymer, aqueous binder systems: carboxy-methyl cellulose with styrene butene rubber, or sodium alginate, with and without a secondary solvent rheology modifier, octanol. The recovery rate of the active material is measured after a short low power ultrasound delamination process, performed in water. Electrodes which exhibit good wettability, as observed through low contact angles, and low tortuosity, delaminate faster with higher recovery rates. Improvements from 2% to 60% black mass recovery is observed with CMC-SBR electrodes with the addition of octanol in the electrode inks, and from 79% to 86% in direct-ink printed compared to tape cast electrodes when using alginate binders. These results highlight the importance of electrode design in the circular manufacturing and recycling of LIBs and lay the groundwork for future research into new design principles for printed electrodes

Electromechanically reconfigurable optical nano-kirigami

© 2021, The Author(s). Kirigami, with facile and automated fashion of three-dimensional (3D) transformations, offers an unconventional approach for realizing cutting-edge optical nano-electromechanical systems. Here, we demonstrate an on-chip and electromechanically reconfigurable nano-kirigami with optical functionalities. The nano-electromechanical system is built on an Au/SiO2/Si substrate and operated via attractive electrostatic forces between the top gold nanostructure and bottom silicon substrate. Large-range nano-kirigami like 3D deformations are clearly observed and reversibly engineered, with scalable pitch size down to 0.975 μm. Broadband nonresonant and narrowband resonant optical reconfigurations are achieved at visible and near-infrared wavelengths, respectively, with a high modulation contrast up to 494%. On-chip modulation of optical helicity is further demonstrated in submicron nano-kirigami at near-infrared wavelengths. Such small-size and high-contrast reconfigurable optical nano-kirigami provides advanced methodologies and platforms for versatile on-chip manipulation of light at nanoscale