Transformative Hydrochloric Acid Treatment of Red Mud for Sustainable Cathode Material Production in Aqueous Zinc Ion Batteries.

The aluminum industry generates a significant amount of red mud as solid waste. This waste is high in mineral content, particularly metal oxides, and difficult to treat, manage, and recycle, resulting in malignant environmental effects. A simple, scalable, and precisely controlled hydrochloric acid treatment transforms the red mud into a useful product by selectively removing electrochemically inactive phases. This process produces a highly porous material with a significantly increased surface area, which effectively serves as the cathode material in an aqueous zinc ion battery (AZIB). RM-HCl, which was treated with acid, had better electrochemical performance than plain red mud (RM). It had an initial specific discharge capacity of 105 mAh g-1 at 0.2 to 1.8 voltage and a current density of 100 mA g-1, which stayed at 63% after 250 cycles. It also showed long-term cyclic stability at high currents of 500 mAg-1 and 1000 mAg-1 for 1000 cycles. The properties of a cathode material made from RM have the potential to be a cost-effective and environmentally friendly option. This study proposes a practical, sustainable, and expandable technique for recycling RM that promotes eco-friendly and sustainable growth in the aluminium industry.

Advanced PEI/PAN Membrane to Suppress Zinc Dendrite Growth in Zinc Metal Batteries.

Aqueous zinc-ion batteries (AZIBs) are a potential new technology in energy storage due to their high energy density, affordability, and environmental friendliness. Unchecked zinc dendrite formation during cycling still hinders the development of AZIBs, resulting in an unstable interface, a short cycling life, a considerable capacity decline, and security issues. Herein, we demonstrate a novel nanofiber membrane based on a polyethylenimine-polyacrylonitrile (PEI-PAN) polymer produced by electrospinning with entangled nanofibers for AZIBs applications. The as-fabricated PEI/PAN membrane has a porous structure that is homogeneous, tortuous, and linked, with high porosity and superior electrolyte wettability. The PEI/PAN membrane has good thermal stability at 200 °C and high ionic conductivity of up to 5.3 x 10-4 S cm-1. This membrane provides Zn/Zn symmetric cells with an ultralong cycle life of over 250 hours at 3 mA cm-2. Additionally, MnO2/Zn cells outperforms commercial filter paper in terms of cycle stability and rate performance. This work demonstrates a simple technique for fabricating advanced nanofiber membranes for AZIBs to modify Zn2+ deposition behavior and improve Zn dendrite resistance.

Facile Transfer Hydrogenation of N-Heteroarenes and Nitroarenes Using Magnetically Recoverable Pd@SPIONs Catalyst.

Catalysts with active, selective, and reusable features are desirable for sustainable development. The present investigation involved the synthesis and characterization of bear-surfaced ultrasmall Pd particles (<1 nm) loaded onto the surface of magnetic nanoparticles (8-10 nm). The amount of Pd loading onto the surface of magnetite is recorded as 2.8 wt %. The characterization process covered the utilization of scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), inductively coupled plasma (ICP), and X-ray photoelectron spectroscopy (XPS) methods. The Pd@Fe3O4 catalyst has shown remarkable efficacy in the hydrogenation of quinoline, resulting in the production of >99% N-ring hydrogenated (py-THQ) product. Additionally, the catalyst facilitated the conversion of nitroarenes into their corresponding aniline derivatives, where hydrogen was achieved by H2O molecules with the aid of tetrahydroxydiboron (THDB) as an equilibrium supportive at 80 °C in 1 h. The high efficiency of a transfer hydrogenation catalyst is closely related to the metal-support synergistic effect. The broader scope of functional group tolerance is evaluated. The potential mechanism underlying the hydrogenation process has been elucidated through the utilization of isotopic labeling investigations. The application of the heterocyclic compound hydrogenation reaction is extended to formulate the medicinally important tubular polymerization inhibitor drug synthesis. The investigation of the recyclability of Pd@Fe3O4 has been conducted.

Development of Membranes and Separators to Inhibit Cross-Shuttling of Sulfur in Polysulfide-Based Redox Flow Batteries: A Review.

The global rapid transition from fossil fuels to renewable energy resources necessitates the implementation of long-duration energy storage technologies owing to the intermittent nature of renewable energy sources. Therefore, the deployment of grid-scale energy storage systems is inevitable. Sulfur-based batteries can be exploited as excellent energy storage devices owing to their intrinsic safety, low cost of raw materials, low risk of environmental hazards, and highest theoretical capacities (gravimetric: 2600 Wh/kg and volumetric: 2800 Wh/L). However, sulfur-based batteries exhibit certain scientific limitations, such as polysulfide crossover, which causes rapid capacity decay and low Coulombic efficiency, thereby hindering their implementation at a commercial scale. In this review article, we focus on the latest research developments between 2012-2023 to improve the separators/membranes and overcome the shuttle effect associated with them. Various categories of ion exchange membranes (IEMs) used in redox batteries, particularly polysulfide redox flow batteries and lithium-sulfur batteries, are discussed in detail. Furthermore, advances in IEM constituents are summarized to gain insights into different fundamental strategies for attaining targeted characteristics, and a critical analysis is proposed to highlight their efficiency in mitigating sulfur cross-shuttling issues. Finally, future prospects and recommendations are suggested for future research toward the fabrication of more effective membranes with desired properties.

Recent Development of Electrolytes for Aqueous Organic Redox Flow Batteries (Aorfbs): Current Status, Challenges, and Prospects.

In recent years, aqueous organic redox flow batteries (AORFBs) have attracted considerable attention due to advancements in grid-level energy storage capacity research. These batteries offer remarkable benefits, including outstanding capacity retention, excellent cell performance, high energy density, and cost-effectiveness. The organic electrolytes in AORFBs exhibit adjustable redox potentials and tunable solubilities in water. Previously, various types of organic electrolytes, such as quinones, organometallic complexes, viologens, redox-active polymers, and organic salts, were extensively investigated for their electrochemical performance and stability. This study presents an overview of recently published novel organic electrolytes for AORFBs in acidic, alkaline, and neutral environments. Furthermore, it delves into the current status, challenges, and prospects of AORFBs, highlighting different strategies to overcome these challenges, with special emphasis placed on their design, composition, functionalities, and cost. A brief techno-economic analysis of various aqueous RFBs is also outlined, considering their potential scalability and integration with renewable energy systems.

Metal Negatrode Supercapatteries: Advancements, Challenges, and Future Perspectives for High-Performance Energy Storage.

Metal negatrode supercapattery (MNSC) is an emerging technology that combines the high energy storage capabilities of batteries with the high-power delivery of supercapacitors, thereby offering promising solutions for various applications, such as energy storage systems, electric vehicles, and portable electronics. This review article presents a comprehensive analysis of the potential of MNSCs as a prospective energy storage technology. MNSCs utilize a specific configuration in which the negatrode consists of a metal or metal-rich electrode, such as sodium, aluminum, potassium, or zinc, whereas the positrode functions as a supercapacitor electrode. The utilization of negatrodes with low electrochemical potential and high electrical conductivity is crucial for achieving high specific energy in energy storage devices, despite facing numerous challenges. The present study discusses the design and fabrication aspects of MNSCs, including the selection of appropriate metal negatrodes, electrolytes, and positrodes, alongside the fundamental operational mechanisms. Additionally, this review explores the challenges encountered in MNSCs and proposes solutions to enhance their performance, such as addressing dendrite formation and instability of metal electrodes.

Preparation and Characterization of Physically Activated Carbon and Its Energetic Application for All-Solid-State Supercapacitors: A Case Study.

Biomass-derived activated carbons have gained significant attention as electrode materials for supercapacitors (SCs) due to their renewability, low-cost, and ready availability. In this work, we have derived physically activated carbon from date seed biomass as symmetric electrodes and PVA/KOH has been used as a gel polymer electrolyte for all-solid-state SCs. Initially, the date seed biomass was carbonized at 600 °C (C-600) and then it was used to obtain physically activated carbon through CO2 activation at 850 °C (C-850). The SEM and TEM images of C-850 displayed its porous, flaky, and multilayer type morphologies. The fabricated electrodes from C-850 with PVA/KOH electrolytes showed the best electrochemical performances in SCs (Lu et al. Energy Environ. Sci., 2014, 7, 2160) application. Cyclic voltammetry was performed from 5 to 100 mV s-1, illustrating an electric double layer behavior. The C-850 electrode delivered a specific capacitance of 138.12 F g-1 at 5 mV s-1, whereas it retained 16 F g-1 capacitance at 100 mV s-1. Our assembled all-solid-state SCs exhibit an energy density of 9.6 Wh kg-1 with a power density of 87.86 W kg-1. The internal and charge transfer resistances of the assembled SCs were 0.54 and 17.86 Ω, respectively. These innovative findings provide a universal and KOH-free activation process for the synthesis of physically activated carbon for all solid-state SCs applications.

A High-Energy Asymmetric Supercapacitor Based on Tomato-Leaf-Derived Hierarchical Porous Activated Carbon and Electrochemically Deposited Polyaniline Electrodes for Battery-Free Heart-Pulse-Rate Monitoring.

A simple and scalable method to fabricate a novel high-energy asymmetric supercapacitor using tomato-leaf-derived hierarchical porous activated carbon (TAC) and electrochemically deposited polyaniline (PANI) for a battery-free heart-pulse-rate monitor is reported. In this study, TAC is prepared by simple pyrolysis, exhibiting nanosheet-type morphology and a high specific surface area of ≈1440 m2 g-1 , and PANI is electrochemically deposited onto carbon cloth. The TAC- and PANI- based asymmetric supercapacitor demonstrates an electrochemical performance superior to that of symmetric supercapacitors, delivering a high specific capacitance of 248 mF cm-2 at a current density of 1.0 mA cm-2 . The developed asymmetric supercapacitor shows a high energy density of 270 µWh cm-2 at a power density of 1400 µW cm-2 , as well as an excellent cyclic stability of ≈95% capacitance retention after 10 000 charging-discharging cycles while maintaining ≈98% Coulombic efficiency. Impressively, the series-connected asymmetric supercapacitors can operate a battery-free heart-pulse-rate monitor extremely efficiently upon solar-panel charging under regular laboratory illumination.