Conformal Engineering of Both Electrodes Toward High-Performance Flexible Quasi-Solid-State Zn-Ion Micro-Supercapacitors.

The severe Zn-dendrite growth and insufficient carbon-based cathode performance are two critical issues that hinder the practical applications of flexible Zn-ion micro-ssupercapacitors (FZCs). Herein, a self-adaptive electrode design concept of the synchronous improvement on both the cathode and anode is proposed to enhance the overall performance of FZCs. Polypyrrole doped with anti-expansion graphene oxide and acrylamide (PPy/GO-AM) on the cathode side can exhibit remarkable electrochemical performance, including decent capacitance and cycling stability, as well as exceptional mechanical properties. Meanwhile, a robust protective polymeric layer containing reduced graphene oxide and polyacrylamide is self-assembled onto the Zn surface (rGO/PAM@Zn) at the anode side, by which the "tip effect" of Zn small protuberance can be effectively alleviated, the Zn-ion distribution homogenized, and dendrite growth restricted. Benefiting from these advantages, the FZCs deliver an excellent specific capacitance of 125 mF cm-2 (125 F cm-3) at 1 mA cm-2, along with a maximum energy density of 44.4 µWh cm-2, and outstanding long-term durability with 90.3% capacitance remained after 5000 cycles. This conformal electrode design strategy is believed to enlighten the practical design of high-performance in-plane flexible Zn-based electrochemical energy storage devices (EESDs) by simultaneously tackling the challenges faced by Zn anodes and capacitance-type cathodes.

Mineral nutrient dynamics in pecans (Carya illinoensis) 'Mahan' grown in southern China.

It is of great significance to study the nutritional characteristics of plants. Further understanding of plant mineral nutrient dynamics can provide theoretical basis for scientific fertilization to improve fruit quality and yield. In this study, eight mineral elements (N, P, K, Ca, Mg, Mn, Zn, B) were measured at regular intervals in leaves and kernels of the pecan "Mahan" planted in southern China. The study discussed the characteristics of mineral nutrient dynamics of pecan through the indicators of concentration, accumulation and cumulative relative rate, a new first proposed indicator, and focused on critical time, intensity, amount of mineral nutrients required in pecan during the fruit developing period, as well as the transfer information of the elements in leaves and kernels. The results show that the mineral nutrient requirements of the leaves and kernels are not identical, with an upward trend in nutrient accumulation within the kernel. The most abundant mineral nutrients in the leaves and kernels were N, K and Ca with Ca being greater than N in leaves. In particular, the concentration of Mn in pecan 'Mahan' is higher than that of other plants, and its Mg content is also higher than that of P in kernels. The dynamic changes of mineral nutrients in walnut showed obvious stages, with a trend of "slow (before mid-July) - fast (mid-July to late August) - slow (late August to late September) - fast (late September to harvest)". The "critical period" of kernels was before mid-July, during which the cumulative relative rates increased rapidly, indicating that the kernels had a great potential to absorb mineral nutrients. Significant accumulation of mineral nutrients occurred from mid-July to late August and late September to the end.

High-Performance and Highly Safe Solvate Ionic Liquid-Based Gel Polymer Electrolyte by Rapid UV-Curing for Lithium-Ion Batteries.

Utilizing ionic liquids (ILs) with low flammability as the precursor component for a gel polymer electrolyte is a smart strategy out of safety concerns. Solvate ionic liquids (SILs) consist of equimolar lithium bis(trifluoromethylsulfonyl)imide and tetraglyme, alleviating the main problems of high viscosity and low Li+ conductivity of conventional ILs. In this study, within a very short time of 30 s, a SIL turns immobile using efficient and controllable UV-curing with an ethoxylated trimethylolpropane triacrylate (ETPTA) network, forming a homogeneous SIL-based gel polymer electrolyte (SGPE) with enhanced thermal stability (216 °C), robust mechanical strength (compression modulus: 1.701 MPa), and high ionic conductivity (0.63 mS cm-1 at room temperature). A Li|SGPE|LiFePO4 cell demonstrates high charge/discharge reversibility and cycling stability with a capacity retention rate of 99.7% after 750 cycles and an average Coulombic efficiency of 99.7%, owing to its excellent electrochemical compatibility with Li-metal. A close-contact electrode/electrolyte interface is formed by in situ curing of the electrolyte on the electrode surface, which enables the pouch full cell to work stably under the conditions of cutting/bending. In view of the excellent mechanical, thermal, and electrochemical performances of SGPE, it is believed to be a promising gel polymer electrolyte for constructing high-safety lithium-ion batteries (LIBs).

Green and facile fabrication of porous titanium dioxide as efficient sulfur host for advanced lithium-sulfur batteries: An air oxidation strategy.

Lithium-sulfur (Li-S) battery has been considered a promising next-generation electrochemical energy storage device due to its high theoretical capacity and high energy density. However, the dissolution and shuttling problems of lithium polysulfides (LiPSs) are major obstacles hindering the performance and application of Li-S batteries. To address these issues, we report the rapid preparation of porous TiO2 nanoparticles (p-TiO2-NPs) as an effective sulfur host for Li-S batteries using a facile, scalable, and green one-step air oxidation strategy. Experimental results reveal that the p-TiO2-NPs have a mesopores-rich structure and strong chemical adsorption capability against LiPSs, which effectively mitigates the dissolution and shuttling of LiPSs by way of physical and chemical adsorptions. Incorporating highly conductive multi-wall carbon nanotubes to interconnect with the active materials, the p-TiO2-NPs-based cathode delivers a high discharge capacity of 1276 mAh g-1 at 0.2 C and stable cycling performance with an ultralow capacity decay rate of 0.0526% per cycle at 1 C over 1200 cycles. This green and facile fabrication strategy can also be extended to other metal carbides to endow an environmentally friendly route for the sustainable development of high-performance Li-S batteries.

Immobilizing Polysulfide by In Situ Topochemical Oxidation Derivative TiC@Carbon-Included TiO2 Core-Shell Sulfur Hosts for Advanced Lithium-Sulfur Batteries.

The performance of lithium-sulfur (Li-S) batteries is greatly hindered by the notorious shuttle effect of lithium polysulfides (LiPSs). To address this issue, in situ topochemical oxidation derivative TiC@carbon-included TiO2 (TiC@C-TiO2 ) core-shell composite is designed and proposed as a multifunctional sulfur host, which integrates the merits of conductive TiC core to facilitate the redox reaction kinetics of sulfur species, and porous C-TiO2 shell to suppress the dissolution and shuttling of LiPSs through chemisorption. A unique dual chemical mediation mechanism is demonstrated for the proposed TiC@C-TiO2 composite that synergistically entraps LiPSs through thiosulfate/polythionate conversion coupled with strong polar-polar interaction. The morphological characterization reveals that the TiC@C-TiO2 -based cathode can well regulate the distribution of electrode materials to retard their accumulation inside the electrode, ensuring effective contact between the active materials and electrolyte. Based on its unique function and structure, the cathode delivers an improved capacity of 1256 mAh g-1 at 0.2C, a remarkable rate capability of 643 mAh g-1 , and an ultralow capacity decay rate of 0.065% per cycle at 2C over 900 cycles. This work not only demonstrates a dual chemical mediation mechanism to immobilize LiPSs, but also provides a universal strategy to construct multifunctional sulfur hosts for advanced Li-S batteries.

High Voltage Microsupercapacitors Fabricated and Assembled by Laser Carving.

Miniaturized and flexible power resources such as supercapacitors with resistance of high voltage play a critical role as potential energy storage devices for implantable and portable electronics because of their convenience, high power density, and long-term stability. Herein, we propose a novel strategy for the fabrication of high voltage microsupercapacitors (HVMSCs) employing porous laser-induced graphene (from polyimide films with alkalization treatment) followed by laser carving of the polyvinyl alcohol/H3PO4 gel electrolyte to realize a series assembly of supercapacitors and significantly increase the voltage resistance. The results elucidated that HVMSCs (3 mm × 21.15 mm) exhibited excellent capacitive performance including exceptional potential window (10 V), high areal capacitance (244 µF/cm2), acceptable power density (274 µW/cm2) and energy density (3.22 µW h/cm2), good electrochemical stability and flexibility at different bending status (0, 45, 90, 135, and 180°), as well as impressive voltage durability more than 5 V in smaller scale (0.5 mm × 5.5 mm). As such, the HVMSCs have great potential to be integrated with microcircuit modules for the next-generation self-powered systems and storage electronic devices in high voltage applications.

Tunable Aryl Imidazolium Recyclable Ionic Liquid with Dual Brønsted-Lewis Acid as Green Catalyst for Friedel-Crafts Acylation and Thioesterification.

Unique tunable aryl imidazolium ionic liquids successfully catalyzed Friedel-Crafts acylation and thioesterification in sealed tubes. These reactions can form a C-C bond and a C-S bond with high atom economy. Ionic liquids exhibited high activity and catalyzed essential reactions with good to excellent yields while retaining their catalytic activities for recycling.

[Effects of Different Altitudes on Soil Microbial PLFA and Enzyme Activity in Two Kinds of Forests].

The soil microbial community is an important part in soil ecosystem, and it is sensitive to the ecological environment. Phospholipid-derived fatty acids ( PLFA ) analysis was used to examine variations in soil microbial community diversity and its influencing factors. The results showed that: there existed 48 PLFAs that were significant in the soil samples from six altitudes. The PLFAs of six altitudes with the highest contents were i16:0, 10Me17:0, 10Me18:0 TBSA. The citrus forest exhibited richer soil PLFAs distribution both in type and amount than those in masson pine. The microbial activity and functional diversity of masson pine were increased with increasing altitudes, and citrus forest gradually decreased, the PLFA content of different microbial groups in each altitude were significantly different. The richness index, Shannon-Wiener index and Pielou evenness index of masson pine in low elevation were holistically higher than those in high elevation. However, the highest richness index of citrus forest was in low altitude, the highest Shannon-Wiener index and Pielou evenness index were in high altitude. The PLFAs content of different microbial groups were closely correlated to the soil enzyme activities and environmental factors. The PLFAs of bacteria, actinomycetes, G⁻ (Gram- positive), G⁺ (Gram-negative) were positively correlated with Ure(urease) , Ive(invertase) , CAT( catalase activity) and forest type, the PLFAs of fungi was significantly correlated with Ure, Ive, CAT, the PLFAs of bacteria, fungi, actinomycetes, G⁻ , G⁺ were significantly negatively or less correlated with elevation. Ure, Ive, CAT, forest type and elevation are the pivotal factors controlling the soil microbial biomass and activities.