Flower-like Highly Open-Structured Binder-Free Zn-Co-Oxide Nanosheet for High-Performance Supercapacitor Electrodes.

Scientific research is being compelled to develop highly efficient and cost-effective energy-storing devices such as supercapacitors (SCs). The practical use of SC devices is hindered by their low energy density and poor rate capability due to the binding agents in fabricating electrodes. Herein, we proposed flower-like highly open-structured binder-free ZnCo2O4 micro-flowers composed of nanosheets supported in nickel foam (ZnCoO@NF) with improved rate capability up to 91.8% when current varied from 2 to 20 A·g-1. The ZnCoO@NF electrode exhibited a superior specific capacitance of 1132 F·g-1 at 2 A·g-1 and revealed 99% cycling stability after 7000 cycles at a high current density of 20 A·g-1. The improved performance of the ZnCoO@NF electrode is attributed to the highly stable structure of the micro/nano-multiscale architecture, which provides both the high conduction of electrons and fast ionic transportation paths simultaneously.

Energy storage properties of hydrothermally processed ultrathin 2D binder-free ZnCo2O4nanosheets.

High energy-density supercapacitors (SCs) with long operating life, cost-effective, and competitive cycling performance is attracted great research attention to competing in the requirements of the modern age. However, despite these benefits, SC hampers inadequate rate-capability and structural deterioration, which primarily affects its commercialization. Herein, ultra-thin two-dimensional (2D) ZnCo2O4nanosheets arein situanchored on the conductive surface of nickel foam (denoted as ZCO@NF) by hydrothermal process. The binder-free ZCO@NF is employed as an electrode for SCs and shows impressive charge storage properties. ZCO@NF electrode exhibited a high capacitance of 1250 (750) and 733 F g-1(440 C g-1) at 2.5 and 20 A g-1, respectively, demonstrating the outstanding rate-capability of 58.6% even at 8 times larger current density. Furthermore, the ZCO@NF electrode exhibits admirable capacitance retention of 96.5% after 10 000 cycles. This impressive performance of the ZCO@NF electrode is attributed to the high surface area which gives a short distance for ion/electron transfer, a high conductivity with extensive electroactive cities, and strong structural stability. The binder-free approach provides a strong relationship between the current collector and the active material, which turns into improved electrochemical operation as an electrode material for SCs.

Toxicity assessment of the extractables from multi-layer coextrusion poly ethylene bags exposed to pH=5 solution containing 4% benzyl alcohol and 0.1 M sodium acetate.

A non-target analysis was developed for the analysis of extractables from multi-layer coextrusion bags exposed to 4% benzyl alcohol solution and 0.1 M sodium acetate at pH = 5 for defined periods (15 day, 45 day and 90 day) according to manufacturer instructions based on the ultra-performance liquid chromatography (UPLC) quadrupole-time of flight mass spectrometry (Q-TOF MS). In order to confirm the extractables, principal component analysis (PCA) was used to indicate the differences among samples of different periods. Then, the extractables were identified based on searching the self-built library or online searching. The total content of extractables of 90 day samples was 589.78 µg/L, and the content was in the range of acceptable levels for pharmaceutical manufacturers. The risk assessment of the extractables were evaluated by Toxtree and T.E.S.T. software to avoid the animals bioexperiment.

Biodegradable MoNx@Mo-foil electrodes for human-friendly supercapacitors.

With the advancement in the field of biomedical research, there is a growing demand for biodegradable electronic devices. Biodegradable supercapacitors (SCs) have emerged as an ideal solution for mitigating the risks associated with secondary surgeries, reducing patient discomfort, and promoting environmental sustainability. In this study, MoNx@Mo-foil was prepared as an active material for biodegradable supercapacitors through high-temperature and nitridation processes. The composite electrode exhibited superior electrochemical performance in both aqueous and solid-state electrolytes. In the case of the solid-state electrolyte, the MoNx@Mo-foil composite electrode-based device demonstrated excellent cycling stability and electrochemical performance. Additionally, the composite electrode exhibited rapid and complete biodegradability in a 3% H2O2 solution. Through detailed experimental analysis and performance testing, we verified the potential application of the MoNx@Mo-foil composite electrode in biodegradable supercapacitors. This work provides a new choice of degradable material for developing biomedical electronic devices.

In-situ construction of binder-free MnO2/MnSe heterostructure membrane for high-performance energy storage in pseudocapacitors.

Manganese (Mn)-based oxides are considered suitable positive electrode materials for supercapacitors (SCs). However, their cycle stability and specific capacitance are significantly hindered by key restrictions such as structural instability and low conductivity. Herein, we demonstrated a novel nanorod (NR)-shaped heterostructured manganese dioxide/manganese selenide membrane (MnO2/MnSe) on carbon cloth (CC) (denoted as MnO2/MnSe-NR@CC) with a high aspect ratio by a straightforward and facile hydrothermal process. Experiments have demonstrated that doping selenium atoms to oxygen sites reduce electronegativity, increasing the intrinsic electronic conductivity of MnO2, decreasing electrostatic interactions with electrolyte ions, and thus boosting the reaction kinetics. Further, the selenium doping results in an amorphous surface with extensive oxygen defects, which contributed to the emergence of additional charge storage sites with pseudocapacitive characteristics. As expected, novel heterostructured MnO2/MnSe-NR@CC as an electrode for SC exhibits a high capacitance of 740.63 F/g at a current density of 1.5 A/g, with excellent cycling performance (93% capacitance retention after 5000 cycles). The MnO2/MnSe-NR@CC exhibited outstanding charge storage capability, dominating capacitive charge storage (84.6% capacitive at 6 mV/s). To examine the practical applications of MnO2/MnSe-NR@CC-ASC as a positive electrode, MnO2/MnSe-NR@CC//AC device was fabricated. The MnO2/MnSe-NR@CC//AC-ASC device performed exceptionally well, with a maximum capacitance of 166.66 F/g at 2 A/g, with a capacitance retention of 94%, after 500 GCD cycles. Additionally, it delivers an energy density of 75.06 Wh/kg at a power density of 1805.1 W/kg and maintains 55.044 Wh/kg at a maximum power density of 18,159 W/kg. This research sheds fresh information on the anionic doping method and has the potential to be applied to the synthesis of positive electrode materials for energy storage applications.

Transition metal dichalcogenide electrodes with interface engineering for high-performance hybrid supercapacitors.

Transition metal dichalcogenides (TMDCs) have been explored in recent years to utilize in electronics due to their remarkable properties. This study reports the enhanced energy storage performance of tungsten disulfide (WS2) by introducing the conductive interfacial layer of Ag between the substrate and active material (WS2). The interfacial layers and WS2 were deposited through a binder free method of magnetron sputtering and three different prepared samples (WS2 and Ag-WS2) were scrutinize via electrochemical measurements. A hybrid supercapacitor was fabricated using Ag-WS2 and activated carbon (AC) since Ag-WS2 was observed to be the most proficient of all three samples. The Ag-WS2//AC devices have attained a specific capacity (Qs) of 224 C g-1, while delivering the maximum specific energy (Es) and specific power (Ps) of 50 W h kg-1 and 4003 W kg-1, respectively. The device was found to be stable enough as it retains 89% capacity and 97% coulombic efficiency after 1000 cycles. Additionally, the capacitive and diffusive currents were obtained through Dunn's model to observe the underlying charging phenomenon at each scan rate.

Effect of Multiple Thermal Cycles on the Microstructure and Mechanical Properties of AISI 1045 Weldments.

AISI 1045 medium carbon steel sheets having 10 mm thickness were subjected to the shielded metal arc welding process with three, five, and seven passes. The variations in the microstructure due to multiple thermal cycles in the heat-affected zone (HAZ), base metal (BM), and fusion zone (FZ) have been investigated and correlated with measured mechanical properties. Upon comparing fracture mechanics and mechanical properties with microstructural observations, it is elucidated that samples become ductile by increasing the number of thermal cycles which can be attributed to the transformations in the ferrite morphology in the HAZ. Based on mechanical, microstructural, and fracture analysis, it is concluded that post-weld heat treatment can be avoided if the number of passes during welding is increased.

Hydrothermal Synthesis of Binder-Free Metallic NiCo2O4 Nano-Needles Supported on Carbon Cloth as an Advanced Electrode for Supercapacitor Applications.

It is of great significance to design electrochemical energy conversion and storage materials with excellent performance to fulfill the growing energy demand. Bimetallic cobalt/nickel-based electrode materials exhibit excellent electrical conductivity compared to mono oxides. However, their potential as electrode materials for high-performance supercapacitors (SCs) is limited because of their poor cycling stability and high-capacity fading. This work demonstrates the synthesis of binder-free bimetallic NiCo2O4 nano-needles supported on CC (NCO@CC) via a facile and scalable hydrothermal process. Excellent electrical conductivity and interconnected nanostructure of NCO@CC nano-needles provide the fast transfer of electrons with numerous channels for ion diffusion. Owing to such features, the binder-free NCO@CC electrode for SC discloses excellent specific capacitance (1476 Fg-1 at 1.5 Ag-1) with 94.25% capacitance retention even after 5000 cycles. From these outstanding electrochemical performances, it can be inferred that NCO@CC nano-needle array-structured electrodes may be potential candidates for SC applications.