Nanoarchitecture factors of solid electrolyte interphase formation via 3D nano-rheology microscopy and surface force-distance spectroscopy

Quantification of solvation forces with amplitude modulation AFM

HYPOTHESIS

Interfacial solvation forces arise from the organisation of liquid molecules near solid surfaces. They are crucial to fundamental phenomena, spanning materials science, molecular biology, and technological applications, yet their molecular details remain poorly understood. Achieving a complete understanding requires imaging techniques, such as three-dimensional atomic force microscopy (3D AFM), to provide atomically resolved images of solid-liquid interfaces (SLIs). However, converting 3D AFM data into accurate tip-sample forces remains challenging, as the process of translating observables into forces is not straightforward.

EXPERIMENTS/SIMULATIONS

This study compares standard amplitude modulation AFM (AM-AFM) force reconstruction methods (FRMs) and identifies their limitations in reconstructing SLI forces. A novel numerical matrix-based FRM specifically designed for AM-AFM is then introduced, aiming to overcome the limitations and inaccuracies found in standard approaches. The new method is validated through simulations and experimental data obtained at the SLI of silicon oxide and water with 3D AFM.

FINDINGS

The proposed matrix-based FRM, differently from standard FRMs, can reconstruct the full SLI interaction at the atomic scale, with no loss of information deriving from the specific choice of AFM experimental parameters or the force functional form. This method unlocks the full spectrum of physical phenomena encoded in the tip-sample interaction at the SLI in AFM experiments, greatly advancing our understanding of interfacial properties and their effects on colloid science, including nanoparticle interactions and molecular self-assembly.

Nonlinear Harmonics: A Gateway to Enhanced Image Contrast and Material Discrimination

Recent advancements in atomic force microscopy (AFM) have enabled detailed exploration of materials at the molecular and atomic levels. These developments, however, pose a challenge: the data generated by microscopic and spectroscopic experiments are increasing rapidly in both size and complexity. Extracting meaningful physical insights from these datasets is challenging, particularly for multilayer heterogeneous nanoscale structures. In this paper, an unsupervised approach is presented to enhance AFM image contrast by analyzing the nonlinear response of a cantilever interacting with a material's surface using a wavelet-based AFM. This method simultaneously measures different frequencies and harmonics in a single scan, without the need for additional hardware and exciting multiple cantilevers' eigenmodes. This developed AFM image contrast enhancement (AFM-ICE) approach employs unsupervised learning, image processing, and image fusion techniques. The method is applied to interpret complex multilayer structures consist of defects, deposited nanoparticles and heterogeneities. Its substantial capability is demonstrated to improve image contrast and differentiate between various components. This methodology can pave the way for rapid and precise determination of material properties with enhanced resolution.

Effect of the Formation Rate on the Stability of Anode-Free Lithium Metal Batteries

Anode-free Li-ion batteries (AFBs), where a Cu current collector is used to plate and strip Li instead of a classic anode, are promising technologies to increase the energy density of batteries. In addition, AFBs are safer and easier to manufacture than competing Li-metal anodes and solid-state batteries. However, the loss of Li inventory that occurs during the operation of AFBs limits their lifespan and practical application. In this study, we find that, in particular, the current density used during the formation of AFBs has a considerable impact on the cycling stability of the cell. We optimize the formation protocol based on experimental and computational observations of thresholds associated with morphological changes in the plated Li and the chemical composition of the solid-electrolyte interphase. Unlike graphite anodes, which require slow formation cycles, AFBs exhibit improved cycling behavior when formed at the highest current densities that avoid dendritic Li formation. We verify that this strategy for optimizing the formation current density is effective for three different electrolyte formulations and, therefore, provides a straightforward universal rationale to optimize the formation protocols for AFBs.

Robust bilayer solid electrolyte interphase for Zn electrode with high utilization and efficiency

Construction of a solid electrolyte interphase (SEI) of zinc (Zn) electrode is an effective strategy to stabilize Zn electrode/electrolyte interface. However, single-layer SEIs of Zn electrodes undergo rupture and consequent failure during repeated Zn plating/stripping. Here, we propose the construction of a robust bilayer SEI that simultaneously achieves homogeneous Zn2+ transport and durable mechanical stability for high Zn utilization rate (ZUR) and Coulombic efficiency (CE) of Zn electrode by adding 1,3-Dimethyl-2-imidazolidinone as a representative electrolyte additive. This bilayer SEI on Zn surface consists of a crystalline ZnCO3-rich outer layer and an amorphous ZnS-rich inner layer. The ordered outer layer improves the mechanical stability during cycling, and the amorphous inner layer homogenizes Zn2+ transport for homogeneous, dense Zn deposition. As a result, the bilayer SEI enables reversible Zn plating/stripping for 4800 cycles with an average CE of 99.95% (± 0.06%). Meanwhile, Zn | |Zn symmetric cells show durable lifetime for over 550 h with a high ZUR of 98% under an areal capacity of 28.4 mAh cm-2. Furthermore, the Zn full cells based on the bilayer SEI functionalized Zn negative electrodes coupled with different positive electrodes all exhibit stable cycling performance under high ZUR.

Water and ions in electrified silica nano-pores: a molecular dynamics study

Solid-liquid interfaces (SLIs) are ubiquitous in science and technology from the development of energy storage devices to the chemical reactions occurring in the biological milieu. In systems involving aqueous saline solutions as the liquid, both the water and the ions are routinely exposed to an electric field, whether the field is externally applied, or originating from the natural surface charges of the solid. In the current study a molecular dynamics (MD) framework is developed to study the effect of an applied voltage on the behaviour of ionic solutions located in a ∼7 nm pore between two uncharged hydrophilic silica slabs. We systematically investigate the dielectric properties of the solution and the organisation of the water and ions as a function of salt concentration. In pure water, the interplay between interfacial hydrogen bonds and the applied field can induce a significant reorganisation of the water orientation and densification at the interface. In saline solutions, at low concentrations and voltages the interface dominates the whole system due to the extended Debye length resulting in a dielectric constant lower than that for the bulk solution. An increase in salt concentration or voltage brings about more localized interfacial effects resulting in dielectric properties closer to that of the bulk solution. This suggests the possibility of tailoring the system to achieve the desired dielectric properties. For example, at a specific salt concentration, interfacial effects can locally increase the dielectric constant, something that could be exploited for energy storage.

Advances in Two-Dimensional Ion-Selective Membranes: Bridging Nanoscale Insights to Industrial-Scale Salinity Gradient Energy Harvesting

Salinity gradient energy, often referred to as the Gibbs free energy difference between saltwater and freshwater, is recognized as "blue energy" due to its inherent cleanliness, renewability, and continuous availability. Reverse electrodialysis (RED), relying on ion-selective membranes, stands as one of the most prevalent and promising methods for harnessing salinity gradient energy to generate electricity. Nevertheless, conventional RED membranes face challenges such as insufficient ion selectivity and transport rates and the difficulty of achieving the minimum commercial energy density threshold of 5 W/m2. In contrast, two-dimensional nanostructured materials, featuring nanoscale channels and abundant functional groups, offer a breakthrough by facilitating rapid ion transport and heightened selectivity. This comprehensive review delves into the mechanisms of osmotic power generation within a single nanopore and nanochannel, exploring optimal nanopore dimensions and nanochannel lengths. We subsequently examine the current landscape of power generation using two-dimensional nanostructured materials in laboratory-scale settings across various test areas. Furthermore, we address the notable decline in power density observed as test areas expand and propose essential criteria for the industrialization of two-dimensional ion-selective membranes. The review concludes with a forward-looking perspective, outlining future research directions, including scalable membrane fabrication, enhanced environmental adaptability, and integration into multiple industries. This review aims to bridge the gap between previous laboratory-scale investigations of two-dimensional ion-selective membranes in salinity gradient energy conversion and their potential large-scale industrial applications.

Intramolecular Charge Transfer of Gold Nanoclusters for pH Indicating

The investigation of the intramolecular charge transfer (ICT) process of gold nanoclusters (AuNCs) is critical to understand the unique features of the nanomaterials, which also benefits their further applications. Herein, 6-methyl-2-thiouracil (CH3-2-TU) and polyvinylpyrrolidone (PVP)-stabilized AuNCs are prepared, and the ICT behaviors are carefully studied. Protonation or deprotonation of the ligands around AuNCs could be used to regulate the ICT state, influencing the electron distribution and band gap. Shifted fluorescence emission phenomena are thus observed, which respond to external pH stimuli. In addition, the AuNCs are developed as color-switchable indicators for the highly sensitive detection of biogenic amines. As a proof of concept, the performance of this strategy in the evaluation of food spoilage by probing pH conditions is validated with satisfactory results. The discoveries in this work offer a convenient route to regulate the optical properties of AuNCs and the design of pH-based sensing applications.