Degradation of Angelica sinensis polysaccharide: Structures and protective activities against ethanol-induced acute liver injury.

Angelica sinensis polysaccharide (ASP) possesses diverse bioactivities; however, its metabolic fate following oral administration remains poorly understood. To intuitively determine its intestinal digestion behavior after oral administration, ASP was labeled with fluorescein, and it was found to accumulate and be degraded in the cecum and colon. Therefore, we investigated the in vitro enzymatic degradation behavior and identified the products. The results showed that ASP could be degraded into fragments with molecular weights similar to those of the fragments observed in vivo. Structural characterization revealed that ASP is a highly branched acid heteropolysaccharide with AG type II domains, and its backbone is predominantly composed of 1,3-Galp, →3,6)-Galp-(1→6)-Galp-(1→, 1,4-Manp, 1,4-Rhap, 1,3-Glcp, 1,2,3,4-Galp, 1,3,4,6-Galp, 1,3,4-GalAp and 1,4-GlcAp, with branches of Araf, Glcp and Galp. In addition, the high molecular weight enzymatic degradation products (ASP H) maintained a backbone structure almost identical to that of ASP, but exhibited only partial branch changes. Then, the results of ethanol-induced acute liver injury experiments revealed that ASP and ASP H reduced the expression of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and malondialdehyde (MDA) and increased the superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) levels, thereby relieving ethanol-induced acute liver injury.

Micro-Bubble F-P Cavity and FBG Cascade Structure-Based Pressure Sensor With Temperature Self-Compensation for Minimally Invasive Surgery.

This paper presents a high-sensitivity optical fiber pressure sensor with temperature self-compensation for pressure measurement in minimally invasive surgery through a cascade structure of Fabry-Perot (F-P) interferometer and fiber Bragg grating (FBG). A micro-bubble is configured at the tip of the fiber to form an F-P cavity that is sensitive to pressure. A loose optical fiber inscribed with an FBG element is cascaded with the F-P cavity leading to temperature compensation for the designed sensor. The sensing theoretical model has been derived and combined with the finite element method (FEM) simulation the sensor structure has been determined as well. Fabrication processing of the designed sensor has been optimized and explored by experiments. Calibration experiment results indicate that the pressure sensitivity of the designed sensor is 8.93 pm/kPa, which is consistent with the simulated value. The temperature coupled error is less than 3.89% leading to a capability for temperature self-compensation. Several heart-vascular simulation experiments have been carried out to investigate the dynamic performance of the designed sensor, which shows the measured pressure errors within this confidence interval of [-2.56%, 2.54%] correspond to high confidence of 0.95. An in-vivo intracranial pressure (ICP) measurement experiment on the rat brain has been conducted to further validate the feasibility and effectiveness of the designed sensor.

Semi-Flooded Sulfur Cathode with Ultralean Absorbed Electrolyte in Li-S Battery.

Lean electrolyte (small E/S ratio) is urgently needed to achieve high practical energy densities in Li-S batteries, but there is a distinction between the cathode's absorbed electrolyte (AE) which is cathode-intrinsic and total added electrolyte (E) which depends on cell geometry. While total pore volume in sulfur cathodes affects AE/S and performance, it is shown here that pore morphology, size, connectivity, and fill factor all matter. Compared to conventional thermally dried sulfur cathodes that usually render "open lakes" and closed pores, a freeze-dried and compressed (FDS-C) sulfur cathode is developed with a canal-capillary pore structure, which exhibits high mean performance and greatly reduces cell-to-cell variation, even at high sulfur loading (14.2 mg cm-2) and ultralean electrolyte condition (AE/S = 1.2 µL mg-1). Interestingly, as AE/S is swept from 2 to 1.2 µL mg-1, the electrode pores go from fully flooded to semi-flooded, and the coin cell still maintains function until (AE/S)min ≈ 1.2 µL mg-1 is reached. When scaled up to Ah-level pouch cells, the full-cell energy density can reach 481 Wh kg-1 as its E/S ≈ AE/S ratio can be reduced to 1.2 µL mg-1, proving high-performance pouch cells can actually be working in the ultralean, semi-flooded regime.

Is graphite lithiophobic or lithiophilic?

Graphite and lithium metal are two classic anode materials and their composite has shown promising performance for rechargeable batteries. However, it is generally accepted that Li metal wets graphite poorly, causing its spreading and infiltration difficult. Here we show that graphite can either appear superlithiophilic or lithiophobic, depending on the local redox potential. By comparing the wetting performance of highly ordered pyrolytic graphite, porous carbon paper (PCP), lithiated PCP and graphite powder, we demonstrate that the surface contaminants that pin the contact-line motion and cause contact-angle hysteresis have their own electrochemical-stability windows. The surface contaminants can be either removed or reinforced in a time-dependent manner, depending on whether the reducing agents (C6→LiC6) or the oxidizing agents (air, moisture) dominate in the ambient environment, leading to bifurcating dynamics of either superfast or superslow wetting. Our findings enable new fabrication technology for Li-graphite composite with a controllable Li-metal/graphite ratio and present great promise for the mass production of Li-based anodes for use in high-energy-density batteries.

High-performance sodium-ion batteries with a hard carbon anode: transition from the half-cell to full-cell perspective.

Hard carbon is an appealing anode material for sodium-ion batteries (SIBs) due to renewable resources, low cost and high specific capacity. Practical full cells based on hard carbon with high energy density and long cyclability are expected to possess application interest for grid-scale energy storage. In this review, following this archetypal use scenario of SIBs, we aim at providing a quantitative full-cell metric for evaluating newly designed anodes or cathodes. Some significant problems in conventional half-cell and full-cell tests, including unfaithful prediction of capacity loss by coulombic efficiency in the full-cell and under-estimated capacity of hard carbon in the half-cell test, are discussed to better assess the actual capacity and cyclability of the hard carbon anode in sodium-matched full cells. Finally, we review rational design of hard carbon itself and the selection of electrolytes from such a full-cell perspective.

Low-temperature synthesized Li4Mn5O12-like cathode with hybrid cation- and anion-redox capacities.

The Li-rich spinel Li4Mn5O12 (Li(Mn5/3Li1/3)O4) historically only shows a reversible cation-redox reaction, with a theoretical capacity of 135.5 mA h g-1. However, we found that a simple 400 °C solid-state synthesis method gives a Li4Mn5O12-like nanoparticulate cathode that yields significant reversible hybrid cation- and anion-redox capacities. A high specific capacity of 212 mA h g-1 was achieved. The reversible anion-redox contribution is attributed to the tiny particle size (<10 nm), which facilitates electron tunneling, and a possible random solid-solution in the Li(Mn5/3Li1/3)O4 lattice due to the low synthesis temperature.

Gassing in Sn-Anode Sodium-Ion Batteries and Its Remedy by Metallurgically Prealloying Na.

Despite the high theoretical energy densities of tin as the anode of sodium-ion batteries, its electrochemical performance has been plagued by the inadequate initial Coulombic efficiency (ICE) and poor cycle life. While it is generally believed that mechanical degradation, namely, pulverization and subsequent loss of electrical contact, is the underlying cause, here, we show that gassing is an essential problem in sodium-ion batteries with Sn anode. Since the gas generation appears at a certain voltage, reducing the voltage by metallurgically prealloying Sn with Na could be a solution, with an additional benefit of compensating for "live" Na loss in future cycles. When the metallurgically alloyed foil is used as the anode in Na3V2(PO4)2F3 (NVPF)//alloy full cells, the ICE is significantly improved from 24.68 to 75%, and from the 2nd cycle to the 100th cycle, the average Coulombic efficiency can be maintained up to 99.44%. The full cell can run for 100 cycles, with acceptable capacity decay to 81.4 mAh/g(NVPF) from the initial 112.5 mAh/g(NVPF).

Full-Cell Cycling of a Self-Supporting Aluminum Foil Anode with a Phosphate Conversion Coating.

Aluminum foil is a promising candidate anode material for lithium-ion batteries (LIBs), due to its high theoretical capacity, low lithiation voltage, and abundance. However, as a matter of fact, it has been a great challenge to make Al foil cycle in full cells at industrially acceptable areal capacities of 2-4 mAh/cm2 for commercial 18650 LIBs and some high-power LIBs. In this study, we defined the concepts of electrochemical true contact area (ECA) (areas with perfect electrolyte/electrode contact) and electrochemical noncontact area (ENA) (referred to regions without electrolyte spread on) for the metal foil anode. An initial ECA/ENA partition would cause severe inhomogeneity of the alloying reaction, cause localized electrode pulverization, and exacerbate ECA/ENA inequality even more. Through a phosphate conversion coating on aluminum foil, we killed two birds with one stone: first, the Al foil with a phosphate conversion coating has improved wettability (characterized by the contact angle that decreased from 35.2 to 15.9°) and favors the elimination of ENA, thus guaranteeing uniform electrochemical contact; also, the coating functions as an artificial solid electrolyte interface, which stabilizes the fragile naturally formed solid electrolyte interface and a "steady-state" electrolyte/electrode interface. Therefore, when pairing the phosphated Al foil anode against a commercial LiFePO4 (LFP) cathode (with ∼2.65 mAh/cm2), it can cycle 120 times without Li excess and stabilizes at 1.27 mAh/cm2.

Organic Thiocarboxylate Electrodes for a Room-Temperature Sodium-Ion Battery Delivering an Ultrahigh Capacity.

Organic room-temperature sodium-ion battery electrodes with carboxylate and carbonyl groups have been widely studied. Herein, for the first time, we report a family of sodium-ion battery electrodes obtained by replacing stepwise the oxygen atoms with sulfur atoms in the carboxylate groups of sodium terephthalate which improves electron delocalization, electrical conductivity and sodium uptake capacity. The versatile strategy based on molecular engineering greatly enhances the specific capacity of organic electrodes with the same carbon scaffold. By introducing two sulfur atoms to a single carboxylate scaffold, the molecular solid reaches a reversible capacity of 466 mAh g-1 at a current density of 50 mA g-1 . When four sulfur atoms are introduced, the capacity increases to 567 mAh g-1 at a current density of 50 mA g-1 , which is the highest capacity value reported for organic sodium-ion battery anodes until now.

Advanced Nanostructured Anode Materials for Sodium-Ion Batteries.

Sodium-ion batteries (NIBs), due to the advantages of low cost and relatively high safety, have attracted widespread attention all over the world, making them a promising candidate for large-scale energy storage systems. However, the inherent lower energy density to lithium-ion batteries is the issue that should be further investigated and optimized. Toward the grid-level energy storage applications, designing and discovering appropriate anode materials for NIBs are of great concern. Although many efforts on the improvements and innovations are achieved, several challenges still limit the current requirements of the large-scale application, including low energy/power densities, moderate cycle performance, and the low initial Coulombic efficiency. Advanced nanostructured strategies for anode materials can significantly improve ion or electron transport kinetic performance enhancing the electrochemical properties of battery systems. Herein, this Review intends to provide a comprehensive summary on the progress of nanostructured anode materials for NIBs, where representative examples and corresponding storage mechanisms are discussed. Meanwhile, the potential directions to obtain high-performance anode materials of NIBs are also proposed, which provide references for the further development of advanced anode materials for NIBs.

Electrophilicity and Nucleophilicity of Boryl Radicals.

We carried out a survey of the relative reactivity of a collection of 91 neutral boryl radicals using density functional calculations. Their reactivities were characterized by four indices, i.e., the global electrophilicity, global nucleophilicity, local electrophilicity, and local nucleophilicity. Particularly, the global electrophilicity and nucleophilicity indices span over a moderately wider range than those of carbon radicals, indicating their potentially broader reactivity. Thus, boryl radicals may be utilized in electrophilic radical reactions, while traditionally they are only considered for nucleophilic radical reactions. In contrast, the local electrophilicity and nucleophilicity indices at the boron center show a different reactivity picture than their global counterparts. The inconsistency is rooted in the low and varying spin density on boron (for most radicals, less than 50%) in different boryl radicals, which is a combinative result of radical stabilization via electron delocalization and the low electronegativity of boron (compared to carbon). In short, the boron character in boryl radicals may be weak and their reactivity is not reflected by the local indices based on boron but by the global ones.

Novel Li[(CF3SO2)(n-C4F9SO2)N]-Based Polymer Electrolytes for Solid-State Lithium Batteries with Superior Electrochemical Performance.

Solid polymer electrolytes (SPEs) would be promising candidates for application in high-energy rechargeable lithium (Li) batteries to replace the conventional organic liquid electrolytes, in terms of the enhanced safety and excellent design flexibility. Herein, we first report novel perfluorinated sulfonimide salt-based SPEs, composed of lithium (trifluoromethanesulfonyl)(n-nonafluorobutanesulfonyl)imide (Li[(CF3SO2)(n-C4F9SO2)N], LiTNFSI) and poly(ethylene oxide) (PEO), which exhibit relatively efficient ionic conductivity (e.g., 1.04 × 10-4 S cm-1 at 60 °C and 3.69 × 10-4 S cm-1 at 90 °C) and enough thermal stability (>350 °C), for rechargeable Li batteries. More importantly, the LiTNFSI-based SPEs could not only deliver the excellent interfacial compatibility with electrodes (e.g., Li-metal anode, LiFePO4 and sulfur composite cathodes), but also afford good cycling performances for the Li|LiFePO4 (>300 cycles at 1C) and Li-S cells (>500 cycles at 0.5C), in comparison with the conventional LiTFSI (Li[(CF3SO2)2N])-based SPEs. The interfacial impedance and morphology of the cycled Li-metal electrodes are also comparatively analyzed by electrochemical impedance spectra and scanning electron microscopy, respectively. These indicate that the LiTNFSI-based SPEs would be potential alternatives for application in high-energy solid-state Li batteries.