ACS Materials Letters最新文献

Employing a flame-retardant solvent (FRS) in the electrolyte has shown great potential for improving the safety of lithium-ion batteries (LIBs). Nevertheless, their poor compatibility with salts and commonly used solvents leads to the formation of a heterogeneous system, which drastically limits their concentration in the electrolyte and consequently deteriorates the safety performance. In this work, we employ a bridging solvent diethyl carbonate to raise the solubility of a highly effective FRS, ethoxy pentafluorocyclotriphosphonitrile (PFPN), to a concentration as high as 75 vol % in the electrolyte. The target electrolyte forms a stable N/P-rich cathode–electrolyte interface to protect the electrode from oxygen evolution and transition-metal ion dissolution, thereby enabling the LiCoO₂ cathode to preserve 72% capacity retention over 500 cycles at 4.62 V. Moreover, this electrolyte can effectively delay occurrence time and improve the critical temperature of thermal runaway of 1 Ah LiCoO₂||graphite pouch cells. Our work proposes a new direction for nonflammable electrolytes toward safe and high-energy LIBs.

This study explores vibrationally assisted delayed fluorescence (VADF) in Mn-doped CsPbBr₃ nanocrystals using Förster resonance energy transfer (FRET). Mn doping enhances the FRET efficiency significantly due to an increase in host fluorescence efficiency, indicating an increase in the radiative pathways due to VADF. We observed that Mn facilitates efficient back-transfer of charge carriers, improving energy transfer to acceptor molecules such as Rhodamine 6G (R6G). The simplicity of tuning optical properties through Mn doping presents a promising method to enhance the energy efficiency in donor–acceptor systems for optoelectronic applications. However, further research on halide concentrations, acceptor molecules, and electron transfer mechanisms is necessary to optimize these systems for effective light energy harvesting.

Bipolar membranes (BPMs) are emerging options for kinetically accelerating water dissociation (WD) in electrochemical applications. Graphene oxide (GO) with abundant oxygenated functional groups is an efficient catalyst within BPMs to decrease the transmembrane potential. However, the dominant catalytic sites on GO for WD in BPMs have not been experimentally identified, and the reported simulative calculation results are controversial. Herein, we prepared carboxylated and partially hydroxylated GO-based BPMs, and for the first time quantitatively unraveled the correlativity between WD performance and carboxyl group content with tailor-designed experiments. By using a simple mechanical ball milling method, we further improved the bulk density of carboxyl on the GO catalyst, which achieved excellent WD performance during an operation of over 130 h operation. This study provides a subtle and facile strategy for catalyst design to advance BPM technologies.

The development of high-energy 5 V-class LiNi_0.5Mn_1.5O₄ batteries is severely limited by the instability of the cathode electrolyte interphase (CEI) at high temperature. Herein, we propose a nonflammable sulfone (SL)-based fluorinated hybrid electrolyte to form stable, uniform, and thin CEI layers, enabling Li||LiNi_0.5Mn_1.5O₄ batteries to achieve elevated electrochemical performance at 60 °C. The formed highly stable inorganic-dominated CEI, comprising Li_xSO_y, Li_xBO_y, and LiF inorganic compositions, exhibits good thermal stability and mechanical strength. Moreover, the robust CEI layer effectively shields the LNMO particles from undesirable side-reactions and stabilizes the interface within the LiNi_0.5Mn_1.5O₄ cathode during high-temperature cycling. In contrast to the conventional electrolyte, the Li||LiNi_0.5Mn_1.5O₄ battery employing a nonflammable SL-based electrolyte exhibits a stable capacity retention of 88.5% after 100 cycles at 60 °C free from the risk of thermal runaway. This study reveals valuable insights into advanced electrolyte technology, paving the way for safer applications of Co-free high-energy batteries in the future.

The production of colloidal metal nanostructures with complex geometries usually involves shape-directing additives, such as metal ions or thiols, which stabilize high-index facets. These additives may however affect the nanoparticles' surface chemistry, hindering applications, e.g., in biology or catalysis. We report herein the preparation of gold bipyramids with no need for additives and shape yields up to 99%, using pentatwinned Au nanorods as seeds and cetyltrimethylammonium chloride as surfactant. For high-growth solution:seed ratios, the bipyramids exhibit an unusual "belted" structure. Three-dimensional electron microscopy revealed the presence of high-index {117}, {115}, and {113} side facets, with {113} and {112} facets at the belt. Belted bipyramids exhibit strong near-field enhancement and high extinction in the near-infrared, in agreement with electromagnetic simulations. These Ag-free bipyramids were used to seed chiral overgrowth using 1,1'-binaphthyl-2,2'-diamine as a chiral inducer, with g-factor up to 0.02, likely the highest reported for bipyramid seeds so far.

Formamidinium (FA)-based perovskites exhibit significant potential for highly efficient photovoltaics due to their promising optoelectronic properties and optimal bandgap. However, the undesired inactive phase arises from multiple crystal nucleation pathways formed by various intermediate phases during the film formation process, persistently accompanying it. FA-based perovskites frequently struggle to form uniform, highly crystalline films. This challenge complicates the development of reliable and highly reproducible crystallization processes for perovskites and the establishment of guidelines for controlling the α-phase formation. In this work, we investigate the role of poly(acrylonitril-co-methyl acrylate) (PAM) to simultaneously control nucleation and subsequent α-phase crystallization. This successfully demonstrates the regulation of oriented crystal growth through the creation of a PAM-PbI₂ intermediate. Ultimately, PAM-modified p–i–n architecture devices obtain a promising power conversion efficiency (PCE) of 25.30%, with V_OC (1.211 V), achieving 95% of the detailed balance limit. Additionally, PAM-modified devices maintain ≥90% of the initial efficiency for 1000 h under 1 sun and 65 °C operation.

Zn-ion batteries (ZIBs) are considered promising alternatives to conventional Li-ion secondary batteries due to their high safety, environmental friendliness, and cost-effectiveness. Despite these advantages, uneven metal plating and stripping, dendrite formation, and passivation and corrosion owing to the hydrogen evolution reaction (HER) have hindered the practical implementation of ZIBs. A promising route for overcoming these problems involves coating the Zn anode with eutectic gallium indium (EGaIn)-based liquid metal (LM) with a strong Zn affinity and growth direction tenability. Despite considerable research on EGaIn-coated Zn anodes for ZIBs, this topic has not been comprehensively reviewed. Hence, this Review introduces the application of LMs to ZIBs and particularly discusses the mitigation of stability issues using LM and the fundamental processes related to Zn anodes. We summarize the progress in this field and suggest promising future research directions to advance ZIBs.

We present a method to synthesize stable and uniform high-quality perovskite nanocrystals (PNCs) by using excess halide to recover surface defects in CsPbBr₃/ZnS core/shell nanocrystals. Use of N-bromosuccinimide as a halide donor recovered surface halide vacancies of bare CsPbBr₃ PNCs during the growth of the ZnS shell, as confirmed by DFT calculations. This approach achieves a high photoluminescence quantum yield of nearly 1, and significantly increases the stability of PNCs under adverse conditions such as high humidity and elevated temperature. CsPbBr₃/ZnS PNC light-emitting diodes demonstrated outstanding luminous characteristics, with a remarkable external quantum efficiency of 12.77% and a maximum luminance of 1449 cd m^–2 at 517 nm. These characteristics of the PNCs will have a wide variety of applications and will help enable development of highly efficient optoelectronic devices.

Herein, we introduce a ZnO–Li₃TaO₄ composite coating designed to stabilize single-crystalline LiNi_0.95Co_0.03Mn_0.015Al_0.005O₂ (sNCMA) in ASSBs with Li₆PS₅Cl. This dual-function coating establishes a Ta-rich surface layer and Zn-doped near-surface regions, as verified by detailed analyses, including atom probe tomography and transmission electron microscopy. The ZnO-Li₃TaO₄ coating markedly enhances both interfacial and structural stabilities, showcasing an exceptional performance in sNCMA|Li₆PS₅Cl|(Li–In) cells at 30 °C (initial discharge capacity of 196 mA h g^–1 with 82.7% capacity retention after 1000 cycles), exceeding the performance of both uncoated or only Li₃TaO₄-coated sNCMA (only 82.5 or 84.2%, respectively, after 200 cycles). The protective role of ZnO-Li₃TaO₄ is corroborated by electrochemical impedance spectroscopy and ex situ X-ray photoelectron spectroscopy. Finally, density functional theory calculations and comparative tests with oxidatively inert Li₂ZrCl₆ catholytes elucidate the enhanced performance mechanism, specifically, the suppression of Ni²⁺ migration by Zn doping, emphasizing the importance of cathode structural stability in all-solid-state batteries.

Sparsely solvating electrolyte (SSE), which can achieve a quasi-solid-phase sulfur reaction path, stands out as a promising strategy to alleviate the dependence on electrolyte usage and construct lean-electrolyte lithium–sulfur (Li–S) batteries. Nonetheless, its formation relies upon a high dosage of salt and diluent, thereby leading to increased electrolyte cost. To this end, we herein customize a localized SSE (LSSE) featuring a low ratio of salt-to-solvent and diluent-to-solvent through alkyl chain tuning. A multimodal 2D nuclear magnetic resonance technique is developed to unveil the Li-ion solvation sheath reorganization, which is crucial for studying the coordination and dynamics in liquid electrolytes. LSSE affords an anion-derived solid electrolyte interface and effective restriction of the shuttling effect; hence, our Li–S batteries can sustain a steady operation under 4 μL mg_S^–1 and 3 mg cm^–2. Our work opens a new avenue for advancing SSE design in the pursuit of pragmatic lean-electrolyte Li–S batteries.