Highly Bright and Compact Alloyed Quantum Rods with Near Infrared Emitting: a Potential Multifunctional Nanoplatform for Multimodal Imaging In Vivo

Controlling synthesis of near‐infrared emitting quantum rods (QRs) for in vivo imaging is a major challenge in the fabrication of multifunctional nanoprobes. Here, a reliable synthetic approach for CdTe _x Se_1–x /ZnS alloy nanocrystals to achieve highly bright (quantum yields up to 80%) with controllable rod‐shape and near‐infrared (650–870 nm) emission is developed. Aspect ratio and emission of QRs are correlated with composition, which can be easily tuned by changing Te and Se mole ratio. It illustrates that the content of Se plays an important role in maintaining the rod‐shape, while Te has a significant impact on emitting of the nanorods. Besides exhibiting great stability over a broad range of pH (4–10) and ion strength (up to 2 mol L^‐1 NaCl solution), these hydrophilic QRs display good photo stability and storage stability. In particular, the specially absorbing of paramagnetic gadolinium ions on the QRs lead to a versatile method to engineer multimodal imaging nanoprobes, which are applied for in vivo lymph node dual‐modal imaging (fluorescence and magnetic resonance imaging). These results suggest a promising strategy for engineering multifunctional imaging nanoprobes with the stable near‐infrared QRs.     

Metal–Organic Framework (MOF) Derived Electrodes with Robust and Fast Lithium Storage for Li‐Ion Hybrid Capacitors

Hybrid metal–organic frameworks (MOFs) demonstrate great promise as ideal electrode materials for energy‐related applications. Herein, a well‐organized interleaved composite of graphene‐like nanosheets embedded with MnO₂ nanoparticles (MnO₂@C‐NS) using a manganese‐based MOF and employed as a promising anode material for Li‐ion hybrid capacitor (LIHC) is engineered. This unique hybrid architecture shows intriguing electrochemical properties including high reversible specific capacity 1054 mAh g^?1 (close to the theoretical capacity of MnO₂, 1232 mAh g^?1) at 0.1 A g^?1 with remarkable rate capability and cyclic stability (90% over 1000 cycles). Such a remarkable performance may be assigned to the hierarchical porous ultrathin carbon nanosheets and tightly attached MnO₂ nanoparticles, which provide structural stability and low contact resistance during repetitive lithiation/delithiation processes. Moreover, a novel LIHC is assembled using a MnO₂@C‐NS anode and MOF derived ultrathin nanoporous carbon nanosheets (derived from other potassium‐based MOFs) cathode materials. The LIHC full‐cell delivers an ultrahigh specific energy of 166 Wh kg^?1 at 550 W kg^?1 and maintained to 49.2 Wh kg^?1 even at high specific power of 3.5 kW kg^?1 as well as long cycling stability (91% over 5000 cycles). This work opens new opportunities for designing advanced MOF derived electrodes for next‐generation energy storage devices.     

Time‐Dependent T1–T2 Switchable Magnetic Resonance Imaging Realized by c(RGDyK) Modified Ultrasmall Fe3O4 Nanoprobes

To achieve the accurate diagnosis of tumor with the magnetic resonance imaging (MRI), nanomaterials‐based contrast agents are developed rapidly. Here, a tumor targeting nanoprobe of c(RGDyK) modified ultrasmall sized iron oxide is reported with high saturation magnetization and high T₁‐weighted imaging capability, attributed to a large number of paramagnetic centers on the surface of nanoprobes and rapid water proton exchange rate (inner sphere model), as well as strong superparamagnetism (outer sphere model). These nanoprobes could actively target and gradually accumulate at the tumor site with a time‐dependent T₁–T₂ contrast enhancement imaging effect. In in vivo MRI experiments, the nanoprobes exhibit the best T₁ contrast enhancement at 30 min after intravenous administration, followed by gradually vanishing and generating T₂ contrast enhancement with increasing time at tumor site. This is likely due to time‐dependent nanoprobes aggregation in tumor, in good agreement with in vitro experiment where aggregated nanoprobes display larger r₂/r₁ value (19.1) than that of the dispersed nanoprobes (2.8). This dynamic property is completely different from other T₁‐T₂ dual‐modal nanoprobes which commonly exhibit the T₁‐ and T₂‐weighted enhancement effect at the same time. To sum up, these c(RGDyK) modified ultrasmall Fe₃O₄ nanoprobes have significant potential to improve the diagnostic accuracy and sensitivity in MRI.     

Controlled Growth of Porous α‐Fe2O3 Branches on β‐MnO2 Nanorods for Excellent Performance in Lithium‐Ion Batteries

Hierarchical nanocomposites rationally designed in component and structure, are highly desirable for the development of lithium‐ion batteries, because they can take full advantages of different components and various structures to achieve superior electrochemical properties. Here, the branched nanocomposite with β‐MnO₂ nanorods as the back‐bone and porous α‐Fe₂O₃ nanorods as the branches are synthesized by a high‐temperature annealing of FeOOH epitaxially grown on the β‐MnO₂ nanorods. Since the β‐MnO₂ nanorods grow along the four‐fold axis, the as‐produced branches of FeOOH and α‐Fe₂O₃ are aligned on their side in a nearly four‐fold symmetry. This synthetic process for the branched nanorods built by β‐MnO₂/α‐Fe₂O₃ is characterized. The branched nanorods of β‐MnO₂/α‐Fe₂O₃ present an excellent lithium‐storage performance. They exhibit a reversible specific capacity of 1028 mAh g^?1 at a current density of 1000 mA g^?1 up to 200 cycles, much higher than the building blocks alone. Even at 4000 mA g^?1, the reversible capacity of the branched nanorods could be kept at 881 mAh g^?1. The outstanding performances of the branched nanorods are attributed to the synergistic effect of different components and the hierarchical structure of the composite. The disclosure of the correlation between the electrochemical properties and the structure/component of the nanocomposites, would greatly benefit the rational design of the high‐performance nanocomposites for lithium ion batteries, in the future.     

A High‐Energy Aqueous Aluminum‐Manganese Battery

Rechargeable aluminum‐ion batteries have drawn considerable attention as a new energy storage system, but their applications are still significantly impeded by critical issues such as low energy density and the lack of excellent electrolytes. Herein, a high‐energy aluminum‐manganese battery is fabricated by using a Birnessite MnO₂ cathode, which can be greatly optimized by a divalence manganese ions (Mn²⁺) electrolyte pre‐addition strategy. The battery exhibits a remarkable energy density of 620 Wh kg^?1 (based on the Birnessite MnO₂ material) and a capacity retention above 320 mAh g^?1 for over 65 cycles, much superior to that with no Mn²⁺ pre‐addition. The electrochemical reactions of the battery are scrutinized by a series of analysis techniques, indicating that the Birnessite MnO₂ pristine cathode is first reduced as Mn²⁺ to dissolve in the electrolyte upon discharge, and Al_xMn_(1?x)O₂ is then generated upon charge, serving as a reversible cathode active material in following cycles. This work provides new opportunities for the development of high‐performance and low‐cost aqueous aluminum‐ion batteries for prospective applications.     

Glucose‐Responsive Bioinorganic Nanohybrid Membrane for Self‐Regulated Insulin Release

A bioinorganic nanohybrid glucose‐responsive membrane is developed for self‐regulated insulin delivery analogous to a healthy human pancreas. The application of MnO₂ nanoparticles as a multifunctional component in a glucose‐responsive, protein‐based membrane with embedded pH‐responsive hydrogel nanoparticles is proposed. The bio‐nanohybrid membrane is prepared by crosslinking bovine serum albumin (BSA)–MnO₂ nanoparticle conjugates with glucose oxidase and catalase in the presence of poly(N‐isopropyl acrylamide‐co‐methacrylic acid) nanoparticles. The preparation and performance of this new nanocomposite material for a glucose‐responsive insulin release system is presented. The activity and stability of immobilized glucose oxidase and the morphology and mechanical properties of the membrane are investigated. The enzymatic activity is well preserved in the membranes. The use of MnO₂ nanoparticles not only reinforces the mechanical strength and the porous structure of the BSA‐based membrane, but enhances the long‐term stability of the enzymes. The in vitro release of insulin across the membrane is modulated by changes in glucose concentration mimicking possible fluctuations of blood‐glucose level in diabetic patients. A four‐fold increase in insulin permeation is observed when the glucose concentration is increased from normal to hyperglycemic levels, which returns to the baseline level when the glucose concentration is reduced to a normal level.     

Remarkable Improvements in Volumetric Energy and Power of 3D MnO2 Microsupercapacitors by Tuning Crystallographic Structures

Transition‐metal oxides as faradaic charge‐storage intermediates sandwiched between conductor and electrolyte are key components to store/deliver high‐density energy in microsupercapacitors for many applications in miniaturized portable electronics and microelectromechanical systems. While the conductor facilitating their electron transports, they generally suffer from a switch of rate‐determining step to their sluggish redox reactions in pseudocapacitive energy storage, during which poor cation accessibility and diffusion leads to high internal resistances and lowers volumetric capacitance and rate performance. Here it is shown that the faradaic processes in a model system of MnO₂ can be radically boosted by tuning crystallographic structures from cryptomelane (α‐MnO₂) to birnessite (δ‐MnO₂). As a result of greatly enhanced Na⁺ accessibility and diffusion, 3D layered crystalline δ‐MnO₂ microelectrodes exhibit volumetric capacitance as high as ≈922 F cm^?3 (≈1.5‐fold higher than α‐MnO₂, ≈617 F cm^?3) and excellent rate performance. This enlists δ‐MnO₂ microsupercapacitor to deliver ultrahigh stack electrical powers (up to ≈295 W cm^?3) while maintaining volumetric energy density much higher than that of thin‐film lithium battery.     

High‐Performance Ionic‐Polymer–Metal Composite: Toward Large‐Deformation Fast‐Response Artificial Muscles

As promising candidates in the field of artificial muscles, ionic‐polymer–metal composites (IPMCs) still cannot simultaneously provide large deformations and fast responses, which has limited their practical applications. In this study, to overcome this issue, a Nafion‐based IPMC with high‐quality metal electrodes is fabricated via novel isopropanol‐assisted electroless plating. The IPMC exhibits a large tip displacement (35.3 mm, 102.3°) under a low direct‐current driving voltage and ultrafast response (>10 Hz) under an alternating‐current (AC) voltage. Furthermore, the simultaneous integration of a large deformation and fast response can be achieved by the IPMC under a high‐frequency (19 Hz) AC voltage, where the largest bending amplitude is 5.9 mm and the highest bending speed reaches 224.2 mm s^?1 (596.2° s^?1). Additionally, the lightweight IPMC exhibits a decent load capacity and can lift objects 20 times heavier. The outstanding performances of the Nafion IPMC are demonstrated by mimicking biological motions such as petal opening/closing, tendril coiling/uncoiling, and high‐frequency wing flapping. This study paves the way for the fabrication of lightweight actuators with simultaneous large displacements and fast responses for promising applications in biomedical devices and bioinspired robotics.     

Nitrogen‐Doped Carbon Quantum Dot Stabilized Magnetic Iron Oxide Nanoprobe for Fluorescence,Magnetic Resonance,and Computed Tomography Triple‐Modal In Vivo Bioimaging

Multimodal imaging, which combines complementary information of two or more imaging modalities, offers huge advantages. In this paper, the synthesis, characterization, and application of superparamagnetic nitrogen‐doped carbon‐iron oxide hybrid quantum dots (C‐Fe₃O₄ QDs) is reported for triple‐modal bioimaging through fluorescence/magnetic resonance/computed tomography (FL/MR/CT). Especially, C‐Fe₃O₄ QDs are synthesized by using poly (γ‐glutamic acid) as a precursor and stabilizer via a green and facile one‐pot hydrothermal approach. The as‐prepared C‐Fe₃O₄ QDs exhibit excellent water dispersibility, wavelength‐tunable FL property with high quantum yield of about 21.6%, good photostability, strong superparamagnetic property as well as favorable biocompatibility. Meanwhile, these C‐Fe₃O₄ QDs also show a transverse relaxivity value (r ₂) of 154.10 mm ^?1 s^?1 for T₂‐weighted MR imaging mode and an observable X‐ray attenuation effect for CT imaging mode. Moreover, the in vivo bioimaging of tumor‐bearing nude mice by combining FL, MR, and CT images further demonstrates that the as‐prepared C‐Fe₃O₄ QDs can be readily and efficiently used in FL/MR/CT triple‐modal tumor imaging. Hence, the new and facile one‐pot synthesis strategy for preparing multifunctional C‐Fe₃O₄ QDs nanoprobes provides a convenient way for achieving an effective and versatile agent for tumorous bioimaging/or diagnostics.     

Nanoscale Parallel Circuitry Based on Interpenetrating Conductive Assembly for Flexible and High‐Power Zinc Ion Battery

High‐rate capability has become an important feature for energy storage devices, but it is often accompanied with a significant reduction in energy density. Therefore, developing an energy storage technology that combines high‐rate capability with high energy density is a great challenge for next‐generation electronic devices. Here, parallel circuitry is constructed at the nanoscale to lower the resistance for ion and electron transport that largely determines the rate performance. The parallel circuitry is constructed through intertwining continuous carbon nanotubes with an interpenetrating conductive assembly based on hierarchically layered MXene (Ti₃C₂T_x ) functionalized by KMnO₄ (MnO_x @Ti₃C₂T_x ). The assembly shows ultrafast rate capability, e.g., maintaining 50% capacity when the current density increases from 0.1 to 10 A g^?1. Investigations of the kinetics and charge storage mechanisms confirm the efficiency of the designed parallel circuitry in improving rate capability by providing rapid pathways for ions and electrons, as well as dividing the current flow evenly into individual MnO_x @Ti₃C₂T_x flakes in the assembly. The flexible MnO_x @Ti₃C₂T_x based electrode endows zinc ion batteries with outstanding mechanical robustness and good power delivering performance. The paradigm presented here paves a new way for designing electrodes with high‐rate capability toward next‐generation energy storage technologies.     

High‐Performance,Air‐Stable,Top‐Gate,p‐Channel WSe2 Field‐Effect Transistor with Fluoropolymer Buffer Layer

High‐performance, air‐stable, p‐channel WSe₂ top‐gate field‐effect transistors (FETs) using a bilayer gate dielectric composed of high‐ and low‐k dielectrics are reported. Using only a high‐k Al₂O₃ as the top‐gate dielectric generally degrades the electrical properties of p‐channel WSe₂, therefore, a thin fluoropolymer (Cytop) as a buffer layer to protect the 2D channel from high‐k oxide forming is deposited. As a result, a top‐gate‐patterned 2D WSe₂ FET is realized. The top‐gate p‐channel WSe₂ FET demonstrates a high hole mobility of 100 cm²_­ V^?1 s^?1 and a I_ON/I_OFF ratio > 10⁷ at low gate voltages (V_GS ca. ?4 V) and a drain voltage (V_DS) of ?1 V on a glass substrate. Furthermore, the top‐gate FET shows a very good stability in ambient air with a relative humidity of 45% for 7 days after device fabrication. Our approach of creating a high‐k oxide/low‐k organic bilayer dielectric is advantageous over single‐layer high‐k dielectrics for top‐gate p‐channel WSe₂ FETs, which will lead the way toward future electronic nanodevices and their integration.     

Nitrogen‐Doped Carbon Networks for High Energy Density Supercapacitors Derived from Polyaniline Coated Bacterial Cellulose

Bacterial cellulose (BC) is used as both template and precursor for the synthesis of nitrogen‐doped carbon networks through the carbonization of polyaniline (PANI) coated BC. The as‐obtained carbon networks can act not only as support for obtaining high capacitance electrode materials such as activated carbon (AC) and carbon/MnO₂ hybrid material, but also as conductive networks to integrate active electrode materials. As a result, the as‐assembled AC//carbon‐MnO₂ asymmetric supercapacitor exhibits a considerably high energy density of 63 Wh kg^?1 in 1.0 m Na₂SO₄ aqueous solution, higher than most reported AC//MnO₂ asymmetric supercapacitors. More importantly, this asymmetric supercapacitor also exhibits an excellent cycling performance with 92% specific capacitance retention after 5000 cycles. Those results offer a low‐cost, eco‐friendly design of electrode materials for high‐performance supercapacitors.     

Breaking the Limits of Ionic Liquid‐Based Supercapacitors: Mesoporous Carbon Electrodes Functionalized with Manganese Oxide Nanosplotches for Dense,Stable, and Wide‐Temperature Energy Storage

Manganese oxide (MnO₂) nanosplotches (NSs) are deposited on N‐ and S‐doped ordered mesoporous carbon (N,S‐CMK‐3) essentially blocking microporosity. The obtained N,S‐CMK‐3/MnO₂ composite materials are assembled into ionic liquid (IL)‐based symmetric supercapacitors, which exhibit a high specific capacitance of 200 F g^?1 (0–3.5 V) at a scan rate of 2 mV s^?1, and good rate stability with 55.5% capacitance retention at a scan rate of 100 mV s^?1. The device can operate in a wide temperature range (?20 to 60 °C), and high cycling stability of N,S‐CMK‐3/MnO₂ composite electrode is demonstrated. Lower energy of ?3.56 eV can be achieved for the adsorption of 1‐ethyl‐3‐methylimidazolium⁺ (EMIM⁺) cation on the edge between MnO₂ NSs and N,S‐CMK‐3 than on the plane of MnO₂ NS (?3.04 eV), both being more preferred than the surface of pristine N,S‐CMK‐3 (?1.52 eV). This strengthening of the ion adsorption at the three‐phase boundary between N,S‐CMK‐3, MnO₂, and IL leads to enhancement of the specific capacity as compared to nondoped or MnO₂‐free reference materials. Supercapacitors based on such composite electrodes show significantly enhanced areal capacity pointing to energy storage in the mesopores rather than in the electrochemical surface layer, demonstrating a new energy storage mechanism in ILs.     

Combined Optical and MR Bioimaging Using Rare Earth Ion Doped NaYF4 Nanocrystals

Here, novel nanoprobes for combined optical and magnetic resonance (MR) bioimaging are reported. Fluoride (NaYF₄) nanocrystals (20–30 nm size) co‐doped with the rare earth ions Gd³⁺ and Er³⁺/Yb³⁺/Eu³⁺ are synthesized and dispersed in water. An efficient up‐ and downconverted photoluminescence from the rare‐earth ions (Er³⁺ and Yb³⁺ or Eu³⁺) doped into fluoride nanomatrix allows optical imaging modality for the nanoprobes. Upconversion nanophosphors (UCNPs) show nearly quadratic dependence of the photoluminescence intensity on the excitation light power, confirming a two‐photon induced process and allowing two‐photon imaging with UCNPs with low power continuous wave laser diodes due to the sequential nature of the two‐photon process. Furthermore, both UCNPs and downconversion nanophosphors (DCNPs) are modified with biorecognition biomolecules such as anti‐claudin‐4 and anti‐mesothelin, and show in vitro targeted delivery to cancer cells using confocal microscopy. The possibility of using nanoprobes for optical imaging in vivo is also demonstrated. It is also shown that Gd³⁺ co‐doped within the nanophosphors imparts strong T1 (Spin‐lattice relaxation time) and T2 (spin‐spin relaxation time) for high contrast MR imaging. Thus, nanoprobes based on fluoride nanophosphors doped with rare earth ions are shown to provide the dual modality of optical and magnetic resonance imaging.     

Electrochemically Derived Graphene‐Like Carbon Film as a Superb Substrate for High‐Performance Aqueous Zn‐Ion Batteries

3D graphene, as a light substrate for active loadings, is essential to achieve high energy density for aqueous Zn‐ion batteries, yet traditional synthesis routes are inefficient with high energy consumption. Reported here is a simplified procedure to transform the raw graphite paper directly into the graphene‐like carbon film (GCF). The electrochemically derived GCF contains a 2D–3D hybrid network with interconnected graphene sheets, and offers a highly porous structure. To realize high energy density, the Na:MnO₂/GCF cathode and Zn/GCF anode are fabricated by electrochemical deposition. The GCF‐based Zn‐ion batteries deliver a high initial discharge capacity of 381.8 mA h g^?1 at 100 mA g^?1 and a reversible capacity of 188.0 mA h g^?1 after 1000 cycles at 1000 mA g^?1. Moreover, a recorded energy density of 511.9 Wh kg^?1 is obtained at a power density of 137 W kg^?1. The electrochemical kinetics measurement reveals the high capacitive contribution of the GCF and a co‐insertion/desertion mechanism of H⁺ and Zn²⁺ ions. First‐principles calculations are also carried out to investigate the effect of Na⁺ doping on the electrochemical performance of layered δ‐MnO₂ cathodes. The results demonstrate the attractive potential of the GCF substrate in the application of the rechargeable batteries.     

Ultrahigh Speed and Broadband Few‐Layer MoTe2/Si 2D–3D Heterojunction‐Based Photodiodes Fabricated by Pulsed Laser Deposition

2D transition metal dichalcogenides are promising candidates for high‐performance photodetectors. However, the relatively low response speed as well as the complex transfer process hinders their wide applications. Herein, for the first time, the fabrication of a few‐layer MoTe₂/Si 2D–3D vertical heterojunction for high‐speed and broadband photodiodes by a pulsed laser deposition technique is reported. Owing to the high junction quality, ultrathin MoTe₂ film thickness, and unique vertical n–n heterojunction structure, the photodiode exhibits excellent device performance in terms of a high responsivity of 0.19 A W^?1 and a large detectivity of 6.8 × 10¹³ Jones. The device is also capable of detecting a broadband light with wavelength spanning from 300 to 1800 nm. More importantly, the device possesses an ultrahigh response speed up to 150 ns with a 3‐dB electrical bandwidth approaching 0.12 GHz. This work paves the way toward the fabrication of novel 2D–3D heterojunctions for high‐performance, ultrafast photodetectors.     

Porous Cu(I) Triazolate Framework and Derived Hybrid Membrane with Exceptionally High Sensing Efficiency for Gaseous Oxygen

Phosphorescent complexes of precious metal ions are widely studied as optical sensing materials for molecular oxygen. Combining the advantages of luminescent complexes and porous matrixes, porous coordination polymers show great potential for oxygen‐sensing, although their sensitivity, requirement of precious metal, and device fabrication remain challenging issues. In this work, the photoluminescence and oxygen‐sensing properties of the porous Cu(I) triazolate framework [Cu(detz)] (MAF‐2, Hdetz = 3,5‐diethyl‐1,2,4‐trizole) is studied in detail, which shows high chemical stability in moisture and water, very long phosphorescent lifetime (116 μs) and large Stokes shift (14 562 cm^?1), as well as considerable oxygen permeability (1.7 × 10^?11 mol cm^?1 s^?1 bar^?1) at ambient conditions, giving rise to exceptionally high luminescence quenching efficiency of 99.7% at 1 bar O₂ (I ₀/I ₁₀₀ = 356) with a perfectly linear Stern‐Volmer plot (K _SV = 356 bar^?1, R ² = 0.9998), fast response and good reversibility. Further, a counter‐diffusion crystal‐growth method was developed to fabricate MAF‐2 thin films protected by silicone rubbers as the first example of soft membrane oxygen sensor based on coordination polymer or metal‐organic framework, which exhibited extraordinary oxygen‐sensing performance (limit of detection = 0.047 mbar) and outstanding mechanical property, as well as outstanding chemical stability even in an acidic atmosphere.     

Positive and Negative Lattice Shielding Effects Co‐existing in Gd (III) Ion Doped Bifunctional Upconversion Nanoprobes

Gadolinium (Gd) doped upconversion nanoparticles (UCNPs) have been well documented as T₁‐MR and fluorescent imaging agents. However, the performance of Gd³⁺ ions located differently in the crystal lattice still remains debatable. Here, a well‐designed model was built based on a seed‐mediated growth technique to systematically probe the longitudinal relaxivity of Gd³⁺ ions within the crystal lattice and at the surface of UCNPs. We found, for the first time, a nearly 100% loss of relaxivity of Gd³⁺ ions buried deeply within crystal lattices (> 4 nm), which we named a “negative lattice shielding effect” (n‐LSE) as compared to the “positive lattice shielding effect” (p‐LSE) for the enhanced upconversion fluorescent intensity. As‐observed n‐LSE was further found to be shell thickness dependent. By suppressing the n‐LSE as far as possible, we optimized the UCNPs' structure design and achieved the highest r₁ value (6.18 mM^?1s^?1 per Gd³⁺ ion) among previously reported counterparts. The potential bimodal imaging application both in vitro and in vivo of as‐designed nano‐probes was also demonstrated. This study clears the debate over the role of bulk and surface Gd³⁺ ions in MRI contrast imaging and paves the way for modulation of other Gd‐doped nanostructures for highly efficient T₁‐MR and upconversion fluorescent bimodal imaging.     

Ultrathin MnO2/Graphene Oxide/Carbon Nanotube Interlayer as Efficient Polysulfide‐Trapping Shield for High‐Performance Li–S Batteries

Ultrathin MnO₂/graphene oxide/carbon nanotube (G/M@CNT) interlayers are developed as efficient polysulfide‐trapping shields for high‐performance Li–S batteries. A simple layer‐by‐layer procedure is used to construct a sandwiched vein–membrane interlayer of thickness 2 µm and areal density 0.104 mg cm^?2 by loading MnO₂ nanoparticles and graphene oxide (GO) sheets on superaligned carbon nanotube films. The G/M@CNT interlayer provides a physical shield against both polysulfide shuttling and chemical adsorption of polysulfides by MnO₂ nanoparticles and GO sheets. The synergetic effect of the G/M@CNT interlayer enables the production of Li–S cells with high sulfur loadings (60–80 wt%), a low capacity decay rate (?0.029% per cycle over 2500 cycles at 1 C), high rate performance (747 mA h g^?1 at a charge rate of 10 C), and a low self‐discharge rate with high capacity retention (93.0% after 20 d rest). Electrochemical impedance spectroscopy, cyclic voltammetry, and scanning electron microscopy observations of the Li anodes after cycling confirm the polysulfide‐trapping ability of the G/M@CNT interlayer and show its potential in developing high‐performance Li–S batteries.     

A Self‐Branched Lamination of Hierarchical Patronite Nanoarchitectures on Carbon Fiber Cloth as Novel Electrode for Ionic Liquid Electrolyte‐Based High Energy Density Supercapacitors

The developments of rationally designed binder‐free metal chalcogenides decorated flexible electrodes are of paramount importance for advanced energy storage devices. Herein, binder‐free patronite (VS₄) flower‐like nanostructures are facilely fabricated on a carbon cloth (CC) using a facile hydrothermal method for high‐performance supercapacitors. The growth density and morphology of VS₄ nanostructures on CC are also controlled by varying the concentrations of vanadium and sulfur sources along with the complexing agent in the growth solution. The optimal electrode with an appropriate growth concentration (VS₄‐CC@VS‐3) demonstrates a considerable pseudocapacitance performance in the ionic liquid (IL) electrolyte (1‐ethyl‐3‐methylimidazolium trifluoromethanesulfonate), with a high operating potential of 2 V. Utilizing VS₄‐CC@VS‐3 as both positive and negative electrodes, the IL‐based symmetric supercapacitor is assembled, which demonstrates a high areal capacitance of 536 mF cm^?2 (206 F g^?1) and excellent cycling durability (93%) with superior energy and power densities of 74.4 µWh cm^?2 (28.6 Wh kg^?1) and 10154 µW cm^?2 (9340 W kg^?1), respectively. As for the high energy storage performance, the device stably energizes various portable electronic applications for a long time, which make the fabricated composite material open up news for the fabrication of fabrics supported binder‐free chalcogenides for high‐performance energy storage devices.