The lithium–sulfur battery is an attractive option for next‐generation energy storage owing to its much higher theoretical energy density than state‐of‐the‐art lithium‐ion batteries. However, the massive volume changes of the sulfur cathode and the uncontrollable deposition of Li2S2/Li2S significantly deteriorate cycling life and increase voltage polarization. To address these challenges, we develop an ϵ‐caprolactam/acetamide based eutectic‐solvent electrolyte, which can dissolve all lithium polysulfides and lithium sulfide (Li2S8–Li2S). With this new electrolyte, high specific capacity (1360 mAh g−1) and reasonable cycling stability are achieved. Moreover, in contrast to conventional ether electrolyte with a low flash point (ca. 2 °C), such low‐cost eutectic‐solvent‐based electrolyte is difficult to ignite, and thus can dramatically enhance battery safety. This research provides a new approach to improving lithium–sulfur batteries in aspects of both safety and performance.

This study examines the translation and rotation of a spherical colloid straddling the (upper) air/liquid interface of a thin, planar, liquid film bounded from below by either a solid or a gas/liquid interface. The goal is to obtain numerical solutions for the hydrodynamic flow in order to understand the influence of the film thickness and the lower interface boundary condition. When the colloid translates on a film above a solid, the viscous resistance increases significantly as the film thickness decreases due to the fluid-solid interaction, while on a free lamella, the drag decreases due to the proximity to the free (gas/liquid) surface. When the colloid rotates, the contact line of the interface moves relative to the colloid surface. If no-slip is assumed, the stress becomes infinite and prevents the rotation. Here finite slip is used to resolve the singularity, and for small values of the slip coefficient, the rotational viscous resistance is dominated by the contact line stress and is surprisingly less dependent on the film thickness and the lower interface boundary condition. For a colloid rotating on a semi-infinite liquid layer, the rotational resistance is largest when the colloid just breaches the interface from the liquid side.

The lithium-sulfur battery is an attractive option for next-generation energy storage owingt oi ts muchh igher theoretical energy density than state-of-the-art lithium-ion batteries.H owever,t he massive volume changes of the sulfur cathode and the uncontrollable deposition of Li 2 S 2 /Li 2 S significantly deteriorate cycling life and increase voltage polarization. To address these challenges,w ed evelop an ecaprolactam/acetamide based eutectic-solvent electrolyte, which can dissolve all lithium polysulfides and lithium sulfide (Li 2 S 8 -Li 2 S). With this new electrolyte,h igh specific capacity (1360 mAh g À1 )a nd reasonable cycling stability are achieved. Moreover,i nc ontrast to conventional ether electrolyte with al ow flash point (ca. 2 8 8C), such low-cost eutectic-solventbased electrolyte is difficult to ignite,and thus can dramatically enhance battery safety.This researchprovides anew approach to improving lithium-sulfur batteries in aspects of both safety and performance. Figure 1. a) Conventional lithium-sulfur batteries with "dead" Li 2 S/ Li 2 S 2 precipitated none-uniformly.b )The proposed structure with all the lithium polysulfides/sulfide soluble. c) The CPL/acetamide mixture bounded by intermolecular hydrogen bond. d) Ah ypotheticald ynamic solvation structure which involves multiple solvent molecules to dissolve Li 2 S. Dashed lines mark the intermolecular interactions.

In recent years, halide perovskites have upstaged decades of development in solar cells by reaching power conversion efficiencies that surpasses polycrystalline silicon performance. The efficiency improvement in the perovskite cells is related to repeated recycling between photons and electron-hole pairs, reduced recombination losses and increased carrier lifetimes. Here, we demonstrate a novel approach towards enhancing the efficiency of perovskite solar cells by invoking the Forster Resonance Energy Transfer (FRET) mechanism. FRET occurs in the near-field region as bacteriorhodopsin (bR) protein and perovskite have similar optical gaps. Titanium dioxide functionalized with bR protein is shown to accelerate the electron injection from excitons produced in the perovskite layer. FRET predicts the strength and range of exciton transport between separated perovskite and bR layers. We show that the cells incorporating bR/TiO 2 layers exhibit much higher photovoltaic performance. These results open the opportunity to develop a new class of bio-perovskite solar cells with improved performance and stability.