Safety-Reinforced Succinonitrile-Based Electrolyte with Interfacial Stability for High-Performance Lithium Batteries

Different contents of fluoroethylene carbonate (FEC) as cosolvent is added into succinonitrile (SN) solution to form a novel electrolyte for lithium batteries. The SN-based electrolyte with 20 wt % FEC exhibits the most favorable properties involving the good thermal stability, wide electrochemical window and high ionic conductivity. Comparing with the commercial electrolyte, the 20% FEC-SN electrolyte demonstrates the advantage of high safety and excellent interfacial compatibility with lithium due to the form of compact and smooth solid electrolyte interphase layer on the anode. LiCoO₂/Li cells using the SN-based electrolyte behave a high reversible discharge capacity of 122.4 mAh g^–1 and keep an outstanding capacity retention of 91% (122.1 mAh g^–1) at 0.5 C after 100 cycles at 25 °C, 50 °C, respectively. More importantly, the soft-package cells with the SN-based electrolyte can withstand harsh surroundings at 120 °C for 30 min without gas emitted, and can still keep the capacity retention of 77% compared to that before heat treatment, significantly higher than traditional commercial electrolyte (0%). All above results indicate the novel SN-based electrolyte can be an excellent alternative electrolyte in a practical lithium battery

Broadly Applicable Strategy for the Fluorescence Based Detection and Differentiation of Glutathione and Cysteine/Homocysteine: Demonstration in Vitro and in Vivo

Glutathione (GSH), cysteine (Cys), and homocysteine (Hcy) are small biomolecular thiols that are present in all cells and extracellular fluids of healthy mammals. It is well-known that each plays a separate, critically important role in human physiology and that abnormal levels of each are predictive of a variety of different disease states. Although a number of fluorescence-based methods have been developed that can detect biomolecules that contain sulfhydryl moieties, few are able to differentiate between GSH and Cys/Hcy. In this report, we demonstrate a broadly applicable approach for the design of fluorescent probes that can achieve this goal. The strategy we employ is to conjugate a fluorescence-quenching 7-nitro-2,1,3-benzoxadiazole (<b>NBD</b>) moiety to a selected fluorophore (Dye) through a sulfhydryl-labile ether linkage to afford nonfluorescent <b>NBD-O-Dye</b>. In the presence of GSH or Cys/Hcy, the ether bond is cleaved with the concomitant generation of both a nonfluorescent <b>NBD-S-R</b> derivative and a fluorescent dye having a characteristic intense emission band (<b>B1</b>). In the special case of Cys/Hcy, the <b>NBD-S-Cys/Hcy</b> cleavage product can undergo a further, rapid, intramolecular Smiles rearrangement to form a new, highly fluorescent <b>NBD-N-Cys/Hcy</b> compound (band <b>B2</b>); because of geometrical constraints, the GSH derived <b>NBD-S-GSH</b> derivative cannot undergo a Smiles rearrangement. Thus, the presence of a single <b>B1</b> or double <b>B1</b> + <b>B2</b> signature can be used to detect and differentiate GSH from Cys/Hcy, respectively. We demonstrate the broad applicability of our approach by including in our studies members of the Flavone, Bodipy, and Coumarin dye families. Particularly, single excitation wavelength could be applied for the probe <b>NBD-OF</b> in the detection of GSH over Cys/Hcy in both aqueous solution and living cells

Naked-Eye Detection of C1–C4 Alcohols Based on Ground-State Intramolecular Proton Transfer

Previous reports of fluorescent sensors for alcohols based on charge-transfer character of their excited state are based on mono-, di-, and tetra-phosphonate cavitands, which are capable of selecting analytes through shape/size selection and various specific H-bonding, CH−π, and cation–dipole interactions. To contrast, color changes based on absorption properties of the ground state are more suitable for direct observation with the naked eye. Three sensitive and selective colorimetric sensors for C1–C4 alcohols have been developed on the basis of alcohol-mediated ground-state intramolecular proton transfer. Reverse proton transfer induced by water achieves a fully reversible reaction. In addition, the solvent color indicates alcohol concentration

Ratiometric Fluorescent Probe for Lysosomal pH Measurement and Imaging in Living Cells Using Single-Wavelength Excitation

A novel lysosome-targeting ratiometric fluorescent probe (CQ-Lyso) based on the chromenoquinoline chromorphore has been developed for the selective and sensitive detection of intracellular pH in living cells. In acidic media, the protonation of the quinoline ring of CQ-Lyso induces an enhanced intramolecular charge transfer (ICT) process, which results in large red-shifts in both the absorption (104 nm) and emission (53 nm) spectra which forms the basis of a new ratiometric fluorescence pH sensor. This probe efficiently stains lysosomes with high Pearson’s colocalization coefficients using LysoTrackerDeep Red (0.97) and LysoTrackerBlue DND-22 (0.95) as references. Importantly, we show that CQ-Lyso quantitatively measures and images lysosomal pH values in a ratiometric manner using single-wavelength excitation

Effects of Cesium Cations in Lithium Deposition via Self-Healing Electrostatic Shield Mechanism

Lithium (Li) dendrite formation is one of the critical challenges for rechargeable Li metal batteries. The traditional method of suppressing Li dendrites, by using high-quality solid electrolyte interphase films, cannot effectively solve this problem. Recently, we proposed a novel self-healing electrostatic shield (SHES) mechanism to achieve dendrite-free Li deposition by adding so-called non-Li⁺ SHES additives in electrolytes, which adsorb but do not deposit on the active sites of Li electrodes and thus force Li to be deposited in the region away from protuberant tips. In this paper, the electrochemical behavior of the cesium cation (Cs⁺) as the typical non-Li cation suitable for the SHES mechanism is further investigated in detail to reveal its effects on preventing the growth of Li dendrites. Typical adsorption behavior rather than chemical reaction is observed. The existence of Cs⁺ cations in the electrolyte does not change the components or structure of the Li surface film, which is consistent with what the SHES mechanism predicts. Various factors affecting the effectiveness of the SHES mechanism are also discussed. The morphologies of the deposited Li films are smooth and uniform during the repeated deposition–stripping cycles and at various current densities (from 0.1 to 1.0 mA cm^–2) by adding just a small amount (0.05 M) of Cs⁺ additive in the electrolyte

Dendrite-Free Lithium Deposition via Self-Healing Electrostatic Shield Mechanism

Rechargeable lithium metal batteries are considered the “Holy Grail” of energy storage systems. Unfortunately, uncontrollable dendritic lithium growth inherent in these batteries (upon repeated charge/discharge cycling) has prevented their practical application over the past 40 years. We show a novel mechanism that can fundamentally alter dendrite formation. At low concentrations, selected cations (such as cesium or rubidium ions) exhibit an effective reduction potential below the standard reduction potential of lithium ions. During lithium deposition, these additive cations form a positively charged electrostatic shield around the initial growth tip of the protuberances without reduction and deposition of the additives. This forces further deposition of lithium to adjacent regions of the anode and eliminates dendrite formation in lithium metal batteries. This strategy may also prevent dendrite growth in lithium-ion batteries as well as other metal batteries and transform the surface uniformity of coatings deposited in many general electrodeposition processes

Dendrite-Free Lithium Deposition via Self-Healing Electrostatic Shield Mechanism

Rechargeable lithium metal batteries are considered the “Holy Grail” of energy storage systems. Unfortunately, uncontrollable dendritic lithium growth inherent in these batteries (upon repeated charge/discharge cycling) has prevented their practical application over the past 40 years. We show a novel mechanism that can fundamentally alter dendrite formation. At low concentrations, selected cations (such as cesium or rubidium ions) exhibit an effective reduction potential below the standard reduction potential of lithium ions. During lithium deposition, these additive cations form a positively charged electrostatic shield around the initial growth tip of the protuberances without reduction and deposition of the additives. This forces further deposition of lithium to adjacent regions of the anode and eliminates dendrite formation in lithium metal batteries. This strategy may also prevent dendrite growth in lithium-ion batteries as well as other metal batteries and transform the surface uniformity of coatings deposited in many general electrodeposition processes

Dendrite-Free Lithium Deposition via Self-Healing Electrostatic Shield Mechanism

Rechargeable lithium metal batteries are considered the “Holy Grail” of energy storage systems. Unfortunately, uncontrollable dendritic lithium growth inherent in these batteries (upon repeated charge/discharge cycling) has prevented their practical application over the past 40 years. We show a novel mechanism that can fundamentally alter dendrite formation. At low concentrations, selected cations (such as cesium or rubidium ions) exhibit an effective reduction potential below the standard reduction potential of lithium ions. During lithium deposition, these additive cations form a positively charged electrostatic shield around the initial growth tip of the protuberances without reduction and deposition of the additives. This forces further deposition of lithium to adjacent regions of the anode and eliminates dendrite formation in lithium metal batteries. This strategy may also prevent dendrite growth in lithium-ion batteries as well as other metal batteries and transform the surface uniformity of coatings deposited in many general electrodeposition processes